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2022 Volume 33 Issue 9
2022, 33(9): 4133-4145
doi: 10.1016/j.cclet.2022.02.045
Abstract:
Hydrogen peroxide (H2O2) is a very simple bioactive small molecule. In living organisms, H2O2 plays an important role in intracellular signaling. It is involved in many physiological processes including cellular physiology, intracellular signaling, oxidative damage and disease progression. The tumor microenvironment enriched with H2O2. Several electrochemical sensors have been developed and some have been put on the market. Such electrochemical sensors provide efficient, cost-effective, rapid and highly selective method of H2O2 detection. So far, much progress has been made in the designing of materials and construction of H2O2 sensors. This review describes the advances in the application of H2O2 electrochemical sensors in cell detection. Enzyme-based sensors have been applied in diverse applications. In addition, recent advancements in nanotechnology have improved the development of nanozymes-based sensors. The application of noble metals, metal oxides, polymers, carbon materials and other two-dimensional materials in the design of H2O2 sensors are discussed in detail. Moreover, the bio-stimulant types of H2O2 sensor are summarized. Finally, the challenges and future perspectives in the application of H2O2 electrochemical sensors in biological detection are discussed.
Hydrogen peroxide (H2O2) is a very simple bioactive small molecule. In living organisms, H2O2 plays an important role in intracellular signaling. It is involved in many physiological processes including cellular physiology, intracellular signaling, oxidative damage and disease progression. The tumor microenvironment enriched with H2O2. Several electrochemical sensors have been developed and some have been put on the market. Such electrochemical sensors provide efficient, cost-effective, rapid and highly selective method of H2O2 detection. So far, much progress has been made in the designing of materials and construction of H2O2 sensors. This review describes the advances in the application of H2O2 electrochemical sensors in cell detection. Enzyme-based sensors have been applied in diverse applications. In addition, recent advancements in nanotechnology have improved the development of nanozymes-based sensors. The application of noble metals, metal oxides, polymers, carbon materials and other two-dimensional materials in the design of H2O2 sensors are discussed in detail. Moreover, the bio-stimulant types of H2O2 sensor are summarized. Finally, the challenges and future perspectives in the application of H2O2 electrochemical sensors in biological detection are discussed.
2022, 33(9): 4146-4156
doi: 10.1016/j.cclet.2022.02.047
Abstract:
Well-developed mitochondria-targeted nanocarriers for function regulation are highly desirable. Numerous studies have been conducted on the treatment of mitochondria-related diseases; however, further improvements are required to develop more effective drug delivery methods. Herein, we comprehensively introduce recent developments progress in rational design of mitochondria-targeted nanocarriers, and discuss the different strategies of available nanocarriers for targeting mitochondria. We also highlight the advantages and disadvantages of various carrier systems that are currently in use. Finally, perspective on new generation for mitochondria-targeted delivery systems in the emerging area of drug-based therapeutics is also discussed.
Well-developed mitochondria-targeted nanocarriers for function regulation are highly desirable. Numerous studies have been conducted on the treatment of mitochondria-related diseases; however, further improvements are required to develop more effective drug delivery methods. Herein, we comprehensively introduce recent developments progress in rational design of mitochondria-targeted nanocarriers, and discuss the different strategies of available nanocarriers for targeting mitochondria. We also highlight the advantages and disadvantages of various carrier systems that are currently in use. Finally, perspective on new generation for mitochondria-targeted delivery systems in the emerging area of drug-based therapeutics is also discussed.
2022, 33(9): 4157-4168
doi: 10.1016/j.cclet.2022.02.051
Abstract:
The emergence of disseminated metastasis is the leading cause of mortality in patients with malignant tumor. The pre-metastatic microenvironment, including the primary tumor-derived components, pre-metastatic niche (PMN), circulating tumor cells (CTCs), micro-metastases, and tumor immune microenvironment (TIM), are the crucial factors to initiate metastasis and form macro-metastases. It may be a more promising strategy for directly targeting pre-metastatic microenvironment-interrelated factors and cells before they have the chance to form secondary tumors to prevent metastasis. During recent years, a variety of nanosystems, with specific microstructures and functional properties, have been devised to selectively target pre-metastatic cells components and interrelated molecular, and exhibited strong potential on anti-metastatic therapy by absorbing and neutralizing primary tumor-derived components, preventing establishment of the PMN, eliminating the CTCs, eradicating the micro-metastases and modulating the TIM. In this review, we comprehensively review the emerging nanosystems based on the pre-metastatic microenvironments. Hopefully, this review can cast new lights for early preventing and attenuating metastatic progression.
The emergence of disseminated metastasis is the leading cause of mortality in patients with malignant tumor. The pre-metastatic microenvironment, including the primary tumor-derived components, pre-metastatic niche (PMN), circulating tumor cells (CTCs), micro-metastases, and tumor immune microenvironment (TIM), are the crucial factors to initiate metastasis and form macro-metastases. It may be a more promising strategy for directly targeting pre-metastatic microenvironment-interrelated factors and cells before they have the chance to form secondary tumors to prevent metastasis. During recent years, a variety of nanosystems, with specific microstructures and functional properties, have been devised to selectively target pre-metastatic cells components and interrelated molecular, and exhibited strong potential on anti-metastatic therapy by absorbing and neutralizing primary tumor-derived components, preventing establishment of the PMN, eliminating the CTCs, eradicating the micro-metastases and modulating the TIM. In this review, we comprehensively review the emerging nanosystems based on the pre-metastatic microenvironments. Hopefully, this review can cast new lights for early preventing and attenuating metastatic progression.
2022, 33(9): 4169-4174
doi: 10.1016/j.cclet.2022.02.049
Abstract:
As an extensively applied therapeutic approach to combat tumors, radiotherapy generates localized ionizing radiation to destruct tumor cells. Despite its importance in clinical oncology, radiotherapy would often cause significant organ toxicity, and its therapeutic effect is limited by tumor hypoxia. Moreover, although abscopal therapeutic effects have occasionally been observed, radiotherapy is still mostly employed as a local treatment method that could hardly control tumor metastases. In recent years, strategies involving biomaterials and nanomedicine have received increasingly high attention to enhance cancer radiotherapy. Beyond sensitizing tumors for radiotherapy via various mechanisms, many biomaterial systems with immune stimulating effects have also been introduced to boost the antitumor immunity post cancer radiotherapy. In this mini-review, we will summarize the progress of different biomaterials and nanomedicine systems in combination with radiotherapy to trigger antitumor immune responses and enhance the efficacy of immunotherapy, and discusses the perspectives and challenges of this research direction aimed at clinical translations.
As an extensively applied therapeutic approach to combat tumors, radiotherapy generates localized ionizing radiation to destruct tumor cells. Despite its importance in clinical oncology, radiotherapy would often cause significant organ toxicity, and its therapeutic effect is limited by tumor hypoxia. Moreover, although abscopal therapeutic effects have occasionally been observed, radiotherapy is still mostly employed as a local treatment method that could hardly control tumor metastases. In recent years, strategies involving biomaterials and nanomedicine have received increasingly high attention to enhance cancer radiotherapy. Beyond sensitizing tumors for radiotherapy via various mechanisms, many biomaterial systems with immune stimulating effects have also been introduced to boost the antitumor immunity post cancer radiotherapy. In this mini-review, we will summarize the progress of different biomaterials and nanomedicine systems in combination with radiotherapy to trigger antitumor immune responses and enhance the efficacy of immunotherapy, and discusses the perspectives and challenges of this research direction aimed at clinical translations.
2022, 33(9): 4175-4178
doi: 10.1016/j.cclet.2022.02.017
Abstract:
Fluorescent dyes play a crucial role in fluorescence imaging and sensing technology. However, there is a dilemma that they are usually intrinsically hydrophobic which lacks of emission in water and modification with ionic groups to access water solubility may result in poor membrane permeability. Fluorescent dyes with strong fluorescence emission in both nonpolar and polar solvents are highly desirable. In this manuscript, we reported a strategy to develop fluorescent BODIPY dyes via installation of amide moiety at meso position of 1, 3, 5, 7-tetramethyl-BODIPY and discovered that N, N'-dialkylsubstituted BODIPY amides possessed highly fluorescent emission with favorable environment-insensitive properties.
Fluorescent dyes play a crucial role in fluorescence imaging and sensing technology. However, there is a dilemma that they are usually intrinsically hydrophobic which lacks of emission in water and modification with ionic groups to access water solubility may result in poor membrane permeability. Fluorescent dyes with strong fluorescence emission in both nonpolar and polar solvents are highly desirable. In this manuscript, we reported a strategy to develop fluorescent BODIPY dyes via installation of amide moiety at meso position of 1, 3, 5, 7-tetramethyl-BODIPY and discovered that N, N'-dialkylsubstituted BODIPY amides possessed highly fluorescent emission with favorable environment-insensitive properties.
2022, 33(9): 4179-4184
doi: 10.1016/j.cclet.2022.02.022
Abstract:
Since antigen and adjuvant are rapid clearance in vivo, insufficient delivery to induce dendritic cells (DCs) maturation and cross-presentation, as well as limited migration efficiency of DCs to secondary lymph organs, greatly hinders the development of DCs-based immunotherapy. Herein, PCL-PEG-PCL polymersomes (PCEP-PS) as antigen and adjuvants delivery nanoplatforms (IMO-PS) were well-designed, which can electrostatically adsorb OVA antigen on the surface via DOTAP lipid and effectively encapsulate OVA antigen into the inner hydrophilic cavity to achieve both initial antigen exposure as well as slow and sustained antigen release, incorporate MPLA within the lipid layer to ligate with extracellular TLR4 of DCs as well as encapsulate IMQ in the hydrophobic membrane to ligate with intracellular TLR7/8 of DCs for activating synergistic immune responses via different signaling pathways. The IMO-PS significantly improved antigen uptake, promoted DCs maturation and cytokines production. DCs treated with IMO-PS could enhance migration into draining lymphoid nodes, and eventually induced antigen-specific CD8+ and CD4+ T cell responses and OVA-specific cytotoxic T lymphocyte (CTL) responses. Prophylactic vaccination of EG7-OVA tumor-bearing mice by IMO-PS + DCs significantly extended tumor-free time, effectively suppressed tumor growth, and greatly extended median survival time. The strategy may provide an effective nanoplatform for co-delivery antigen and dual-adjuvants in a spatio-temporally programmed manner for DC-based cancer immunotherapy.
Since antigen and adjuvant are rapid clearance in vivo, insufficient delivery to induce dendritic cells (DCs) maturation and cross-presentation, as well as limited migration efficiency of DCs to secondary lymph organs, greatly hinders the development of DCs-based immunotherapy. Herein, PCL-PEG-PCL polymersomes (PCEP-PS) as antigen and adjuvants delivery nanoplatforms (IMO-PS) were well-designed, which can electrostatically adsorb OVA antigen on the surface via DOTAP lipid and effectively encapsulate OVA antigen into the inner hydrophilic cavity to achieve both initial antigen exposure as well as slow and sustained antigen release, incorporate MPLA within the lipid layer to ligate with extracellular TLR4 of DCs as well as encapsulate IMQ in the hydrophobic membrane to ligate with intracellular TLR7/8 of DCs for activating synergistic immune responses via different signaling pathways. The IMO-PS significantly improved antigen uptake, promoted DCs maturation and cytokines production. DCs treated with IMO-PS could enhance migration into draining lymphoid nodes, and eventually induced antigen-specific CD8+ and CD4+ T cell responses and OVA-specific cytotoxic T lymphocyte (CTL) responses. Prophylactic vaccination of EG7-OVA tumor-bearing mice by IMO-PS + DCs significantly extended tumor-free time, effectively suppressed tumor growth, and greatly extended median survival time. The strategy may provide an effective nanoplatform for co-delivery antigen and dual-adjuvants in a spatio-temporally programmed manner for DC-based cancer immunotherapy.
2022, 33(9): 4185-4190
doi: 10.1016/j.cclet.2022.02.052
Abstract:
Nanoscale metal organic frameworks (NMOFs) have been widely reported in biomedical field for their unique porous structure and tunable multifunctionality. However, when administrated in vivo, the protein corona will be formed on the surface of NMOFs, significantly affecting their biodistribution, pharmacokinetics and drug release. Few studies paid attention to the protein corona formation process and its influencing factors of NMOFs. As a well-established strategy for altering structure features of NMOFs, the organic ligand modification may have effect on the protein corona formation process, which is to be investigated. In this study, the zirconium (Zr)-based UIO66 was chosen as model NMOFs, the organic ligand of which was modified with amino group (-NH2) or carboxyl group (-COOH) to synthesize UIO66-NH2 and UIO66-2COOH, respectively. Bovine serum albumin (BSA) was chosen as model protein to investigate the protein corona formation process of NMOFs. The current results showed that the -COOH modification remarkably enhanced the BSA adsorption on NMOFs while -NH2 slightly decreased the protein binding affinity. These differences may be ascribed to the two different dominate protein corona formation modes, i.e., surface coating mode and porous embedded mode. The protein corona formation did not affect the crystal phase of NMOFs but increased the content of α-helix of BSA. Ultimately, upon protein corona formation, the cellular uptake of NMOFs was significantly affected. We believe our study will provide a new research paradigm to the design and applications of NMOFs.
Nanoscale metal organic frameworks (NMOFs) have been widely reported in biomedical field for their unique porous structure and tunable multifunctionality. However, when administrated in vivo, the protein corona will be formed on the surface of NMOFs, significantly affecting their biodistribution, pharmacokinetics and drug release. Few studies paid attention to the protein corona formation process and its influencing factors of NMOFs. As a well-established strategy for altering structure features of NMOFs, the organic ligand modification may have effect on the protein corona formation process, which is to be investigated. In this study, the zirconium (Zr)-based UIO66 was chosen as model NMOFs, the organic ligand of which was modified with amino group (-NH2) or carboxyl group (-COOH) to synthesize UIO66-NH2 and UIO66-2COOH, respectively. Bovine serum albumin (BSA) was chosen as model protein to investigate the protein corona formation process of NMOFs. The current results showed that the -COOH modification remarkably enhanced the BSA adsorption on NMOFs while -NH2 slightly decreased the protein binding affinity. These differences may be ascribed to the two different dominate protein corona formation modes, i.e., surface coating mode and porous embedded mode. The protein corona formation did not affect the crystal phase of NMOFs but increased the content of α-helix of BSA. Ultimately, upon protein corona formation, the cellular uptake of NMOFs was significantly affected. We believe our study will provide a new research paradigm to the design and applications of NMOFs.
2022, 33(9): 4191-4196
doi: 10.1016/j.cclet.2022.01.083
Abstract:
Downregulated pro-apoptotic protein in cancer cells compromises the chemotherapy by a cytotoxic drug. Here, we report co-delivery of a pro-apoptotic protein, caspase 3 (Cas 3), and cytotoxic agent, oridonin (ORD), for synergistic cancer treatment, using a method of liposome-based anchoring and core encapsulation. First, ORD is modified with hyaluronic acid (HA) to improve its solubility. Then, the targeted co-delivery system is prepared by assembling the conjugate HA-ORD onto the Cas 3-loaded liposomes, which the surface HA can target the CD44 receptor on cancer cells. In vitro, the co-loaded liposomes (120 nm) are specifically taken up by 4T1 cells and endow a 1.5-fold increase of Cas 3. After intravenous injection into the tumor-bearing mice, the liposomes accumulate in the tumor with high efficacy and significantly inhibit tumor growth via promoting apoptosis and anti-proliferation of cancer cells. Mechanistically, the co-delivery works synergistically by upregulating the activated Cas form, cleaved-Cas 3.
Downregulated pro-apoptotic protein in cancer cells compromises the chemotherapy by a cytotoxic drug. Here, we report co-delivery of a pro-apoptotic protein, caspase 3 (Cas 3), and cytotoxic agent, oridonin (ORD), for synergistic cancer treatment, using a method of liposome-based anchoring and core encapsulation. First, ORD is modified with hyaluronic acid (HA) to improve its solubility. Then, the targeted co-delivery system is prepared by assembling the conjugate HA-ORD onto the Cas 3-loaded liposomes, which the surface HA can target the CD44 receptor on cancer cells. In vitro, the co-loaded liposomes (120 nm) are specifically taken up by 4T1 cells and endow a 1.5-fold increase of Cas 3. After intravenous injection into the tumor-bearing mice, the liposomes accumulate in the tumor with high efficacy and significantly inhibit tumor growth via promoting apoptosis and anti-proliferation of cancer cells. Mechanistically, the co-delivery works synergistically by upregulating the activated Cas form, cleaved-Cas 3.
2022, 33(9): 4197-4202
doi: 10.1016/j.cclet.2022.01.086
Abstract:
Although targeted therapy and immunotherapy are now shining in the treatment of some cancers, chemotherapy is still the cornerstone of drug treatment for many cancer patients. The emergence of chemotherapy prodrugs can improve the drug activity and reduce the side effects of chemotherapy. When used, the tumor microenvironment has characteristics different from normal tissues, and the existence of the microenvironment provided a more convenient way to design responsive nanodrugs. Herein, we designed a glutathione (GSH)-responsive prodrug nanogels for enhancing tumor chemotherapy. In the nanogels of HHNP, 10-hydroxycamptothecin (HCPT) played an essential role in killing cancer cells. HCPT was jointed with a cross-linker agent with disulfide bond and was further coated with polyethylene glycol, which not only prolonged the half-life of the drug, but also made HCPT accurate transport to the tumor fractions and achieved precise and controllable release. The proposal of HHNP effectively retained the biological activity of the drug, and introduced functions such as targeting, selective release and biodegradation, which greatly improved the medical efficiency of the drug and effectively reduced the toxic and side effects. This chemotherapeutic prodrug nanogel offers a new window for constructing efficient drug delivery platform.
Although targeted therapy and immunotherapy are now shining in the treatment of some cancers, chemotherapy is still the cornerstone of drug treatment for many cancer patients. The emergence of chemotherapy prodrugs can improve the drug activity and reduce the side effects of chemotherapy. When used, the tumor microenvironment has characteristics different from normal tissues, and the existence of the microenvironment provided a more convenient way to design responsive nanodrugs. Herein, we designed a glutathione (GSH)-responsive prodrug nanogels for enhancing tumor chemotherapy. In the nanogels of HHNP, 10-hydroxycamptothecin (HCPT) played an essential role in killing cancer cells. HCPT was jointed with a cross-linker agent with disulfide bond and was further coated with polyethylene glycol, which not only prolonged the half-life of the drug, but also made HCPT accurate transport to the tumor fractions and achieved precise and controllable release. The proposal of HHNP effectively retained the biological activity of the drug, and introduced functions such as targeting, selective release and biodegradation, which greatly improved the medical efficiency of the drug and effectively reduced the toxic and side effects. This chemotherapeutic prodrug nanogel offers a new window for constructing efficient drug delivery platform.
2022, 33(9): 4203-4207
doi: 10.1016/j.cclet.2022.03.007
Abstract:
Fluorescence (FL) active 8-aryl guanosine derivatives were prepared and applied for cation mediated self-assembly to form the H-bonded G8-quadruplexes. The p-cyano (p-CN) and 8-anthracene (8-An) substituted guanosines were identified to give the strongest fluorescence with the formation of G8-octamers (G8) both in solution (NMR) and solid state (X-ray). This well-defined G8-octamer system has provided the first direct evidence on the self-assembled G-quadruplex fluorescence emission with aggregation-induced emission (AIE), which could be applied as the foundation for FL molecular probe design toward G-quadruplex recognition.
Fluorescence (FL) active 8-aryl guanosine derivatives were prepared and applied for cation mediated self-assembly to form the H-bonded G8-quadruplexes. The p-cyano (p-CN) and 8-anthracene (8-An) substituted guanosines were identified to give the strongest fluorescence with the formation of G8-octamers (G8) both in solution (NMR) and solid state (X-ray). This well-defined G8-octamer system has provided the first direct evidence on the self-assembled G-quadruplex fluorescence emission with aggregation-induced emission (AIE), which could be applied as the foundation for FL molecular probe design toward G-quadruplex recognition.
2022, 33(9): 4208-4212
doi: 10.1016/j.cclet.2022.01.081
Abstract:
Since the concept of aptamer emerged, many scientists have launched a rich field of research around it. However, few nucleic acids aptamer which use cell as target can be put into practical applications. We believe that a great deal of this lies in the complexity and irreproducibility of aptamer screening experiments themselves. The complexity is due to the cumbersome processes and the technical requirements for laboratory personnel, whereas irreproducibility arises from the fact that the starting point of such screens is nucleic acid libraries with random fragments, and that different libraries directly determine the differences or even the success or failure of screening results. The complexity and irreproducibility mentioned above, in turn, lead to the inability of this experiment to unfold on a large scale, which naturally cannot lead to excellent results for practical applications. In response to this problem, our group has developed an instrument for automated screening of tumor cell nucleic acid aptamers and characterized the properties of nucleic acid aptamers obtained using this instrument in a comprehensive manner.
Since the concept of aptamer emerged, many scientists have launched a rich field of research around it. However, few nucleic acids aptamer which use cell as target can be put into practical applications. We believe that a great deal of this lies in the complexity and irreproducibility of aptamer screening experiments themselves. The complexity is due to the cumbersome processes and the technical requirements for laboratory personnel, whereas irreproducibility arises from the fact that the starting point of such screens is nucleic acid libraries with random fragments, and that different libraries directly determine the differences or even the success or failure of screening results. The complexity and irreproducibility mentioned above, in turn, lead to the inability of this experiment to unfold on a large scale, which naturally cannot lead to excellent results for practical applications. In response to this problem, our group has developed an instrument for automated screening of tumor cell nucleic acid aptamers and characterized the properties of nucleic acid aptamers obtained using this instrument in a comprehensive manner.
2022, 33(9): 4213-4218
doi: 10.1016/j.cclet.2022.03.041
Abstract:
Stabilizing triplet excited states is important for room temperature phosphorescence (RTP) materials to achieve multifunctional applications in humid environment. However, due to the lack of preparation strategies, the realization of RTP materials in water still faces challenges. Herein, a new design strategy was presented to achieve RTP in water by confining carbonized polymer dots (CPDs) in amino functional mesoporous silica (MSNs-NH2). The as-prepared MSNs-CPDs aqueous dispersion exhibited blue afterglow, lasting more than 3 s to naked eyes. The triplet excited states were protected from non-radiative deactivation by the double-confinement effect including covalent bonding fixation and mesoporous structure confinement. The MSNs-CPDs inherited the structure of MSNs-NH2, so the stability of morphology and properties were superior to CPDs and even most of silica-based CPDs RTP materials. A water-related encryption technique demonstrated the promising application of MSNs-CPDs as smart materials in the field of information security. Besides, the possibility of potential application in ion detection was also explored.
Stabilizing triplet excited states is important for room temperature phosphorescence (RTP) materials to achieve multifunctional applications in humid environment. However, due to the lack of preparation strategies, the realization of RTP materials in water still faces challenges. Herein, a new design strategy was presented to achieve RTP in water by confining carbonized polymer dots (CPDs) in amino functional mesoporous silica (MSNs-NH2). The as-prepared MSNs-CPDs aqueous dispersion exhibited blue afterglow, lasting more than 3 s to naked eyes. The triplet excited states were protected from non-radiative deactivation by the double-confinement effect including covalent bonding fixation and mesoporous structure confinement. The MSNs-CPDs inherited the structure of MSNs-NH2, so the stability of morphology and properties were superior to CPDs and even most of silica-based CPDs RTP materials. A water-related encryption technique demonstrated the promising application of MSNs-CPDs as smart materials in the field of information security. Besides, the possibility of potential application in ion detection was also explored.
2022, 33(9): 4219-4222
doi: 10.1016/j.cclet.2022.03.006
Abstract:
Sulfur dioxide and its derivative sulfite widely existed in air, water as the environment pollutant. Sulfite is also commonly used as preservative and additive in fresh fruits, vegetables, wines and pharmaceutical materials. Due to sulfite is closely related with human diseases, it is very urgent for the sensitive and rapid quantification of sulfite in various samples. In our study, a turn-on near infrared (NIR) fluorescent probe (MDQ) was developed for sulfite detection based on a Michael addition reaction, with high sensitivity (LOD 4.16 nmol/L), selectivity and fast response time (400 s). Using MDQ, a quantify method for sulfite in traditional Chinese medicines (TCMs) was developed with the advantages of high precision, accuracy and convenient operation. Furthermore, according to the photophysical property of MDQ, a portable fluorescence detector is designed to quantify sulfite for TCMs and surface water in Dalian city of China. Therefore, the developed fluorescent probe MDQ and portable fluorescent detector as a rapid inspection instrument were successfully used to real-time monitor the sulfite in various complex samples.
Sulfur dioxide and its derivative sulfite widely existed in air, water as the environment pollutant. Sulfite is also commonly used as preservative and additive in fresh fruits, vegetables, wines and pharmaceutical materials. Due to sulfite is closely related with human diseases, it is very urgent for the sensitive and rapid quantification of sulfite in various samples. In our study, a turn-on near infrared (NIR) fluorescent probe (MDQ) was developed for sulfite detection based on a Michael addition reaction, with high sensitivity (LOD 4.16 nmol/L), selectivity and fast response time (400 s). Using MDQ, a quantify method for sulfite in traditional Chinese medicines (TCMs) was developed with the advantages of high precision, accuracy and convenient operation. Furthermore, according to the photophysical property of MDQ, a portable fluorescence detector is designed to quantify sulfite for TCMs and surface water in Dalian city of China. Therefore, the developed fluorescent probe MDQ and portable fluorescent detector as a rapid inspection instrument were successfully used to real-time monitor the sulfite in various complex samples.
2022, 33(9): 4223-4228
doi: 10.1016/j.cclet.2022.03.008
Abstract:
Herein we presented a general strategy for in situ assembly of intramolecular charge-transfer (ICT)-based light-up fluorophores via bioorthogonal Suzuki-Miyaura cross-coupling reaction. By introducing iodo group at the appropriate position, five fluorophores with different scaffolds including naphthalimide, coumarin, naphthalene sulfonate, nitrobenzoxadiazole, and acetonaphthone, were designed as bioorthogonal multicolor fluorogenic probes, which could produce significant fluorescence enhancement and high fluorescence quantum yield after Suzuki-Miyaura reaction with aryl boronic acid or boronate. Manipulating the substituents and π scaffold in the fluorophores allows fine-tuning of their photophysical properties. With this strategy, we succeeded in peptide conjugation, no-wash fluorogenic protein labeling, and mitochondria-selective bioorthogonal imaging in live cells.
Herein we presented a general strategy for in situ assembly of intramolecular charge-transfer (ICT)-based light-up fluorophores via bioorthogonal Suzuki-Miyaura cross-coupling reaction. By introducing iodo group at the appropriate position, five fluorophores with different scaffolds including naphthalimide, coumarin, naphthalene sulfonate, nitrobenzoxadiazole, and acetonaphthone, were designed as bioorthogonal multicolor fluorogenic probes, which could produce significant fluorescence enhancement and high fluorescence quantum yield after Suzuki-Miyaura reaction with aryl boronic acid or boronate. Manipulating the substituents and π scaffold in the fluorophores allows fine-tuning of their photophysical properties. With this strategy, we succeeded in peptide conjugation, no-wash fluorogenic protein labeling, and mitochondria-selective bioorthogonal imaging in live cells.
2022, 33(9): 4229-4232
doi: 10.1016/j.cclet.2022.01.087
Abstract:
Available online The abnormal carboxylesterase (CES) expression is closely related to many diseases such as hyperlipidemia, atherosclerosis, obesity, liver cancer, type 2 diabetes mellitus and gastrointestinal stromal tumors. The detection of a single enzyme in practical samples is often constrained by the structural diversity of CESs. Thus, the development of broad-carboxylesterase responsive fluorescent probe, which can detect the presence of wide variety of CESs, may provide overall or category information from another point of view, supplementing the deficiency of single detection for CES subspecies. Organelle lysosome is involved in various cell processes, such as cell signaling, apoptosis, secretion, and energy metabolism. Up to date, lysosome-targeted fluorescent probes, especially those with red emission (over 550 nm, with relatively low biological harmfulness), for CES detection are still rare. A lysosomes-targeted red fluorescent probe CES-Lyso was designed to monitor intracellular a variety of carboxylesterases alteration with wonderful selectivity and sensitivity, which was further applied to distinguish different derived breast cancer cells and monitor carboxylesterase activity in the anticancer drug treatment.
Available online The abnormal carboxylesterase (CES) expression is closely related to many diseases such as hyperlipidemia, atherosclerosis, obesity, liver cancer, type 2 diabetes mellitus and gastrointestinal stromal tumors. The detection of a single enzyme in practical samples is often constrained by the structural diversity of CESs. Thus, the development of broad-carboxylesterase responsive fluorescent probe, which can detect the presence of wide variety of CESs, may provide overall or category information from another point of view, supplementing the deficiency of single detection for CES subspecies. Organelle lysosome is involved in various cell processes, such as cell signaling, apoptosis, secretion, and energy metabolism. Up to date, lysosome-targeted fluorescent probes, especially those with red emission (over 550 nm, with relatively low biological harmfulness), for CES detection are still rare. A lysosomes-targeted red fluorescent probe CES-Lyso was designed to monitor intracellular a variety of carboxylesterases alteration with wonderful selectivity and sensitivity, which was further applied to distinguish different derived breast cancer cells and monitor carboxylesterase activity in the anticancer drug treatment.
2022, 33(9): 4233-4237
doi: 10.1016/j.cclet.2022.02.020
Abstract:
A series of near-infrared (NIR) fluorescent substrates (NDRO-1~8) derived from fluorophore NDRH with different volumes of ester bond as the recognition group were designed and synthesized for the detection of acetylcholinesterase (AChE), among which NDRO-1 with the smallest acetate group displayed the highest activity toward AChE. The detection limit of NDRO-1 for sensing AChE was 0.32 µg/mL, and Km was 6.40 µmol/L, indicating ultra-sensitivity and good affinity of NDRO-1 toward AChE. NDRO-1 was used to detect the inhibitory of four kinds of pesticides including methamidophos, dichlorvos, and the detection limit was lower than 50 µg/L, which was further used in pesticide residues detection.
A series of near-infrared (NIR) fluorescent substrates (NDRO-1~8) derived from fluorophore NDRH with different volumes of ester bond as the recognition group were designed and synthesized for the detection of acetylcholinesterase (AChE), among which NDRO-1 with the smallest acetate group displayed the highest activity toward AChE. The detection limit of NDRO-1 for sensing AChE was 0.32 µg/mL, and Km was 6.40 µmol/L, indicating ultra-sensitivity and good affinity of NDRO-1 toward AChE. NDRO-1 was used to detect the inhibitory of four kinds of pesticides including methamidophos, dichlorvos, and the detection limit was lower than 50 µg/L, which was further used in pesticide residues detection.
2022, 33(9): 4238-4242
doi: 10.1016/j.cclet.2022.03.047
Abstract:
Room temperature phosphorescence (RTP) films have recently attracted increasing attention due to their excellent luminescent properties for information encryption, optoelectronic devices, and sensors. However, polyvinyl alcohol (PVA) films with abundant hydrogen bonds to suppress triplet energy dissipation suffered from the humidity induced phosphorescence quenching under storage in the air for a long time. In this work, poly(acrylic acid) (PAA) was selected to crosslink PVA matrix through esterification reactions for preparing water resistant RTP films. The blue, cyan, and orange emissive RTP films were successfully obtained by incorporating three different organic compounds into PVA-PAA crosslinking films. Crosslinking strategy significantly improved the phosphorescence emissions of the doped films, and effectively blocked the absorption of water molecular, leading to the excellent photostability of the developed films. As a proof of concept, the white light phosphorescence film and anti-counterfeiting applications were successfully demonstrated.
Room temperature phosphorescence (RTP) films have recently attracted increasing attention due to their excellent luminescent properties for information encryption, optoelectronic devices, and sensors. However, polyvinyl alcohol (PVA) films with abundant hydrogen bonds to suppress triplet energy dissipation suffered from the humidity induced phosphorescence quenching under storage in the air for a long time. In this work, poly(acrylic acid) (PAA) was selected to crosslink PVA matrix through esterification reactions for preparing water resistant RTP films. The blue, cyan, and orange emissive RTP films were successfully obtained by incorporating three different organic compounds into PVA-PAA crosslinking films. Crosslinking strategy significantly improved the phosphorescence emissions of the doped films, and effectively blocked the absorption of water molecular, leading to the excellent photostability of the developed films. As a proof of concept, the white light phosphorescence film and anti-counterfeiting applications were successfully demonstrated.
2022, 33(9): 4243-4247
doi: 10.1016/j.cclet.2022.02.048
Abstract:
In the recent decade, GO has emerged as an amazing 2D nanomaterial for developing DNA-based biosensors due to its fluorescence quenching properties, whereas similar research based on rGO was reported rarely. Herein, a novel multi-pyrene functionalized G-rich DNA probe based on the screened rGO showed much higher fluorescence quenching efficiency and excimer emission than that of universal GO. Different from the universal thrombin detection of the G4-forming aptamer-TBA(GGTTGGTGTGGTTGG), the original telomeric sequence is used in this study. The excimer emission "ON-OFF" switch amplified the response of thrombin detection is as low as 50 units. Furthermore, for four pyrene moieties that are sited in a crowded steric circumstance, the melting temperature (Tm) values and molecular dynamics simulations showed a positive effect on duplex G-quadruplex or GDNA·cDNA stability, without disturbing its helix structure.
In the recent decade, GO has emerged as an amazing 2D nanomaterial for developing DNA-based biosensors due to its fluorescence quenching properties, whereas similar research based on rGO was reported rarely. Herein, a novel multi-pyrene functionalized G-rich DNA probe based on the screened rGO showed much higher fluorescence quenching efficiency and excimer emission than that of universal GO. Different from the universal thrombin detection of the G4-forming aptamer-TBA(GGTTGGTGTGGTTGG), the original telomeric sequence is used in this study. The excimer emission "ON-OFF" switch amplified the response of thrombin detection is as low as 50 units. Furthermore, for four pyrene moieties that are sited in a crowded steric circumstance, the melting temperature (Tm) values and molecular dynamics simulations showed a positive effect on duplex G-quadruplex or GDNA·cDNA stability, without disturbing its helix structure.
2022, 33(9): 4248-4252
doi: 10.1016/j.cclet.2022.02.050
Abstract:
Two unprecedented polycyclic spirooliganones C and D (1 and 2) with a novel spiro[bicyclo[2.2.2]octane-2, 2′-bicyclo[3.1.0]hexane] carbon skeleton, one known dimeric prenylated C6C3 compound (3), and a pair of new enantiomeric prenylated C6C3 compounds (+)-5 and (−)-5 together with their direct precursors (+)-4 and (−)-4 were isolated from the roots of Illicium oligandrum. Their structures and absolute configurations were elucidated by spectroscopic analysis, single crystal X-ray diffraction data, and electronic circular dichroism calculations. A possible biosynthetic pathway for compounds 1 and 2 involving the Diels-Alder reaction between (−)-sabinene and cyclic prenylated tetrahydropyrano-type C6C3 compounds was proposed. The characteristic prenylated C6C3 compounds (+)-4 and (−)-4 were separated on a chiral stationary phase and their absolute configurations were determined by calculated ECD for the first time. In the antiviral bioassays, compounds 1 and (+)-5 exhibited significant inhibitory activity against CVB3 with IC50 values of 11.11 µmol/L and 1.11 µmol/L, respectively. Compounds 1 and 2 also showed moderate inhibition against influenza A (H1N1) virus.
Two unprecedented polycyclic spirooliganones C and D (1 and 2) with a novel spiro[bicyclo[2.2.2]octane-2, 2′-bicyclo[3.1.0]hexane] carbon skeleton, one known dimeric prenylated C6C3 compound (3), and a pair of new enantiomeric prenylated C6C3 compounds (+)-5 and (−)-5 together with their direct precursors (+)-4 and (−)-4 were isolated from the roots of Illicium oligandrum. Their structures and absolute configurations were elucidated by spectroscopic analysis, single crystal X-ray diffraction data, and electronic circular dichroism calculations. A possible biosynthetic pathway for compounds 1 and 2 involving the Diels-Alder reaction between (−)-sabinene and cyclic prenylated tetrahydropyrano-type C6C3 compounds was proposed. The characteristic prenylated C6C3 compounds (+)-4 and (−)-4 were separated on a chiral stationary phase and their absolute configurations were determined by calculated ECD for the first time. In the antiviral bioassays, compounds 1 and (+)-5 exhibited significant inhibitory activity against CVB3 with IC50 values of 11.11 µmol/L and 1.11 µmol/L, respectively. Compounds 1 and 2 also showed moderate inhibition against influenza A (H1N1) virus.
2022, 33(9): 4253-4256
doi: 10.1016/j.cclet.2022.03.032
Abstract:
Two pairs of fluorescent natural products, talarolactones (+)/(−)-A and (+)/(−)-C [(+)/(−)-1 and (+)/(−)-2], were discovered and characterized as a new family of circularly polarized luminescence-active small organic molecules (CPL-SOMs) with high fluorescence efficiency and fascinating CPL properties. The CPL (|glum|) levels of enantiomerically pure (+)/(−)-1 and (+)/(−)-2 in solution falls into the usual range (10−5−10−3) considering their pure organic nature, but the sign of CPL were found to be closely related to the absolute configuration of C-8. The high agreement of the measured CPL spectra of (+)/(−)-1 and (+)/(−)-2 with the time-dependent density functional theory (TDDFT) calculated ones demonstrated the usefulness of CPL-calculation as a unique method for stereochemical assignment. This study may open up a new perspective for the stereochemical studies and the future development of CPL materials.
Two pairs of fluorescent natural products, talarolactones (+)/(−)-A and (+)/(−)-C [(+)/(−)-1 and (+)/(−)-2], were discovered and characterized as a new family of circularly polarized luminescence-active small organic molecules (CPL-SOMs) with high fluorescence efficiency and fascinating CPL properties. The CPL (|glum|) levels of enantiomerically pure (+)/(−)-1 and (+)/(−)-2 in solution falls into the usual range (10−5−10−3) considering their pure organic nature, but the sign of CPL were found to be closely related to the absolute configuration of C-8. The high agreement of the measured CPL spectra of (+)/(−)-1 and (+)/(−)-2 with the time-dependent density functional theory (TDDFT) calculated ones demonstrated the usefulness of CPL-calculation as a unique method for stereochemical assignment. This study may open up a new perspective for the stereochemical studies and the future development of CPL materials.
2022, 33(9): 4257-4260
doi: 10.1016/j.cclet.2022.01.084
Abstract:
Guided by MS/MS molecular networks strategy, chlospicenes A and B (1 and 2), the first example of cyclopropane moiety cracked lindenane sesquiterpene Michael addition dimers, along with their biogenetic analogues (3 and 4), were targetedly discovered from the roots of Chloranthus henryi. Their structures including absolute configurations were characterized by NMR, ECD and X-ray diffraction analysis. The plausible biogenic pathway speculation indicated that cyclopropylcarbinyl rearrangement may dominate the key crack of cyclopropane moiety. In addition, compounds 1 and 2 showed significant anti-nonalcoholic steatohepatitis (NASH) activity in free fatty acid (FFA)-induced HepG2 cells by decreasing intracellular lipid accumulation.
Guided by MS/MS molecular networks strategy, chlospicenes A and B (1 and 2), the first example of cyclopropane moiety cracked lindenane sesquiterpene Michael addition dimers, along with their biogenetic analogues (3 and 4), were targetedly discovered from the roots of Chloranthus henryi. Their structures including absolute configurations were characterized by NMR, ECD and X-ray diffraction analysis. The plausible biogenic pathway speculation indicated that cyclopropylcarbinyl rearrangement may dominate the key crack of cyclopropane moiety. In addition, compounds 1 and 2 showed significant anti-nonalcoholic steatohepatitis (NASH) activity in free fatty acid (FFA)-induced HepG2 cells by decreasing intracellular lipid accumulation.
2022, 33(9): 4261-4263
doi: 10.1016/j.cclet.2022.03.003
Abstract:
A novel Diels-Alder adduct possesses a 6/6/6/5/6/6/6/6 octacyclic skeleton featured with bicyclo[2.2.2]octane moiety, biseupyiheoid A (1), along with another decacyclic 6/6/6/3/5/6/5/6/6/6 fused diterpenoid dimer, bisfischoid C (2), were isolated from Euphorbia fischeriana. Their structures were determined by spectroscopic, X-ray crystallographic approaches, and quantum mechanical calculations. The structural features of 1 and 2 were hypothesized to involve intramolecular Diels-Alder reactions with different coupling patterns. Dimer 1 showed antiproliferative activity through apoptosis activation in LoVo cells.
A novel Diels-Alder adduct possesses a 6/6/6/5/6/6/6/6 octacyclic skeleton featured with bicyclo[2.2.2]octane moiety, biseupyiheoid A (1), along with another decacyclic 6/6/6/3/5/6/5/6/6/6 fused diterpenoid dimer, bisfischoid C (2), were isolated from Euphorbia fischeriana. Their structures were determined by spectroscopic, X-ray crystallographic approaches, and quantum mechanical calculations. The structural features of 1 and 2 were hypothesized to involve intramolecular Diels-Alder reactions with different coupling patterns. Dimer 1 showed antiproliferative activity through apoptosis activation in LoVo cells.
2022, 33(9): 4264-4268
doi: 10.1016/j.cclet.2021.12.009
Abstract:
Forrestiacids C (1) and D (2), a pair of C-25 epimeric triterpene–diterpene adducts were isolated from the needles and twigs of the vulnerable conifer Pseudotsuga forrestii. This unprecedented class of compounds might be generated via an intermolecular Michael addition reaction of a rearranged 6/6/5/5-fused spiro-lanostene with an abietene. Their structures were established by spectroscopic data and X-ray crystallography. The adducts showed inhibitory activities against the ATP-citrate lyase (ACL) and acetyl-CoA carboxylase 1 (ACC1), two rate-limiting enzymes in the de novo lipogenesis pathway.
Forrestiacids C (1) and D (2), a pair of C-25 epimeric triterpene–diterpene adducts were isolated from the needles and twigs of the vulnerable conifer Pseudotsuga forrestii. This unprecedented class of compounds might be generated via an intermolecular Michael addition reaction of a rearranged 6/6/5/5-fused spiro-lanostene with an abietene. Their structures were established by spectroscopic data and X-ray crystallography. The adducts showed inhibitory activities against the ATP-citrate lyase (ACL) and acetyl-CoA carboxylase 1 (ACC1), two rate-limiting enzymes in the de novo lipogenesis pathway.
2022, 33(9): 4269-4272
doi: 10.1016/j.cclet.2021.12.073
Abstract:
The metal-free S–S bond exchange reaction of symmetrical disulfides catalyzed by NFSI is described. This novel protocol provides a facile and efficient approach to accessing important unsymmetrical disulfides. Furthermore, this strategy could also be utilized in the late-stage functionalization of amino acids, drugs, and natural products. The broad substrate scope, good functional group tolerance and easy accessibility of catalyst indicate that this strategy affords a green and practical complementary method to various unsymmetrical disulfides.
The metal-free S–S bond exchange reaction of symmetrical disulfides catalyzed by NFSI is described. This novel protocol provides a facile and efficient approach to accessing important unsymmetrical disulfides. Furthermore, this strategy could also be utilized in the late-stage functionalization of amino acids, drugs, and natural products. The broad substrate scope, good functional group tolerance and easy accessibility of catalyst indicate that this strategy affords a green and practical complementary method to various unsymmetrical disulfides.
2022, 33(9): 4273-4276
doi: 10.1016/j.cclet.2021.12.075
Abstract:
A catalytic asymmetric hydroxylative dearomatization reaction has been disclosed, and the products can smoothly transform into spiroannulation adducts by simply treated with a base under mild conditions. Novel in-situ generated magnesium catalytic methods are developed by application of combinational ligands. Related concise transformaitons of the spiroannulation adducts have been carried out.
A catalytic asymmetric hydroxylative dearomatization reaction has been disclosed, and the products can smoothly transform into spiroannulation adducts by simply treated with a base under mild conditions. Novel in-situ generated magnesium catalytic methods are developed by application of combinational ligands. Related concise transformaitons of the spiroannulation adducts have been carried out.
2022, 33(9): 4277-4280
doi: 10.1016/j.cclet.2022.01.020
Abstract:
A method for stereoselective construction of Z-monofluoroalkenes by nickel-catalyzed defluorinative coupling of gem-difluoroalkenes in mild conditions was described. The combination of lithium organoborate and ZnBr2 generated in situ lithium aryl zincates, which facilitates the transmetalation step of the nickel-catalyzed cross coupling reaction.
A method for stereoselective construction of Z-monofluoroalkenes by nickel-catalyzed defluorinative coupling of gem-difluoroalkenes in mild conditions was described. The combination of lithium organoborate and ZnBr2 generated in situ lithium aryl zincates, which facilitates the transmetalation step of the nickel-catalyzed cross coupling reaction.
2022, 33(9): 4281-4286
doi: 10.1016/j.cclet.2022.01.041
Abstract:
Hybrid quantum mechanics/molecular mechanics calculations were performed to elucidate how [MnIIIporphyrin]+X−-based metal-organic frameworks (MOFs) catalyze the [2 + 1] cycloisomerization of enynes and why zwitterionic MOFs exhibit strong activity in Lewis acid catalysis. The calculations showed that zwitterionic MOFs have a "pure cationic active center" leading to a concerted nucleophilic attack pathway with lower barriers. In contrast, metals with coordinating anions have reduced electrophilicity, resulting in a stepwise radical-type pathway with much higher barriers. Further calculations showed the nature of catalysis was strongly depended on the charge on the anion ligand. A good linear relationship between the NPA charge and barrier was found, and verified by 73 anions with small derivations, which presents a universal adaptive character for various coordinated anions.
Hybrid quantum mechanics/molecular mechanics calculations were performed to elucidate how [MnIIIporphyrin]+X−-based metal-organic frameworks (MOFs) catalyze the [2 + 1] cycloisomerization of enynes and why zwitterionic MOFs exhibit strong activity in Lewis acid catalysis. The calculations showed that zwitterionic MOFs have a "pure cationic active center" leading to a concerted nucleophilic attack pathway with lower barriers. In contrast, metals with coordinating anions have reduced electrophilicity, resulting in a stepwise radical-type pathway with much higher barriers. Further calculations showed the nature of catalysis was strongly depended on the charge on the anion ligand. A good linear relationship between the NPA charge and barrier was found, and verified by 73 anions with small derivations, which presents a universal adaptive character for various coordinated anions.
2022, 33(9): 4287-4292
doi: 10.1016/j.cclet.2022.01.077
Abstract:
A nickel-catalyzed reductive cross-coupling reactions between polyfluoroarenes and alkyl electrophiles is reported to access substituted fluoroarenes through chelation-assisted C–F activation. Diverse primary and secondary alkyl (pseudo)halides can be employed to couple with polyfluoroarenes, showing excellent regioselectivity. Furthermore, the nickel-catalyzed asymmetric cross-coupling of polyfluoroarenes with racemic alkyl halides is preliminarily explored. In addition, the practicability of the title transformation is also demonstrated by total synthesis of losmapimod and an analog as key steps. The developed method exhibits many advantages, including economic catalytic systems, commercially available alkyl electrophiles, and lack of sensitive organometallic reagents.
A nickel-catalyzed reductive cross-coupling reactions between polyfluoroarenes and alkyl electrophiles is reported to access substituted fluoroarenes through chelation-assisted C–F activation. Diverse primary and secondary alkyl (pseudo)halides can be employed to couple with polyfluoroarenes, showing excellent regioselectivity. Furthermore, the nickel-catalyzed asymmetric cross-coupling of polyfluoroarenes with racemic alkyl halides is preliminarily explored. In addition, the practicability of the title transformation is also demonstrated by total synthesis of losmapimod and an analog as key steps. The developed method exhibits many advantages, including economic catalytic systems, commercially available alkyl electrophiles, and lack of sensitive organometallic reagents.
2022, 33(9): 4293-4297
doi: 10.1016/j.cclet.2022.01.013
Abstract:
A new, stable and scalable reagent for deuteriodifluoromethylthiolation (deuterated N-difluoromethylthiophthalimide, PhthSCF2D) has been developed. This reagent can be applied for the photocatalytic radical deuteriodifluoromethylthiolation of various olefins and aldehydes (30 examples). Meanwhile, it can achieve the electrophilic deuteriodifluoromethylthiolation of a series of electrophilic substrates including electron-rich arenes, aryl/vinylboronicacids, alkynes, amines, thiols and β-ketoesters (22 examples). Some complex molecules can also be applied in both radical and electrophilic deuteriodifluoromethylthiolation using PhthSCF2D as the reagent.
A new, stable and scalable reagent for deuteriodifluoromethylthiolation (deuterated N-difluoromethylthiophthalimide, PhthSCF2D) has been developed. This reagent can be applied for the photocatalytic radical deuteriodifluoromethylthiolation of various olefins and aldehydes (30 examples). Meanwhile, it can achieve the electrophilic deuteriodifluoromethylthiolation of a series of electrophilic substrates including electron-rich arenes, aryl/vinylboronicacids, alkynes, amines, thiols and β-ketoesters (22 examples). Some complex molecules can also be applied in both radical and electrophilic deuteriodifluoromethylthiolation using PhthSCF2D as the reagent.
2022, 33(9): 4298-4302
doi: 10.1016/j.cclet.2022.01.028
Abstract:
While N-alkenoxypyridinium salts are widely used for the synthesis of α-functionalized ketones via umpolung strategy, such approaches are usually limited to special nucleophiles at high temperatures. Herein, we developed an alternative photoinduced N-heterocyclic carbene (NHC)- mediated functionalization of N-alkenoxypyridinium salts with various nucleophiles, including tetramethylammonium azide, secondary amines, aryl and alkyl thiols, and even the challenging C(sp3)-nucleophiles, under mild conditions. A cascade radical-radical coupling/nucleophilic substitution sequence was proposed, wherein the NHC enabled the formation of a photoactive electron donor-acceptor complex for α-iodo ketone synthesis.
While N-alkenoxypyridinium salts are widely used for the synthesis of α-functionalized ketones via umpolung strategy, such approaches are usually limited to special nucleophiles at high temperatures. Herein, we developed an alternative photoinduced N-heterocyclic carbene (NHC)- mediated functionalization of N-alkenoxypyridinium salts with various nucleophiles, including tetramethylammonium azide, secondary amines, aryl and alkyl thiols, and even the challenging C(sp3)-nucleophiles, under mild conditions. A cascade radical-radical coupling/nucleophilic substitution sequence was proposed, wherein the NHC enabled the formation of a photoactive electron donor-acceptor complex for α-iodo ketone synthesis.
2022, 33(9): 4303-4305
doi: 10.1016/j.cclet.2022.01.046
Abstract:
Herein, we reported a convenient and efficient multicomponent reaction of indoles, selenium powder and unactivated alkyl halides. This protocol provides a practical, and facile approach for the synthesis of 3-alkylselenindole derivatives. The advantages of this strategy include mild and transition-metal-free conditions, broad functional group tolerance, the use of simple and easily accessible seleniium powder and alkyl halides as coupling partners. More importantly, the reaction proceeded smoothly with a large scale (> 10 g, > 90% yield), which further highlighted the potential application of this selenation strategy.
Herein, we reported a convenient and efficient multicomponent reaction of indoles, selenium powder and unactivated alkyl halides. This protocol provides a practical, and facile approach for the synthesis of 3-alkylselenindole derivatives. The advantages of this strategy include mild and transition-metal-free conditions, broad functional group tolerance, the use of simple and easily accessible seleniium powder and alkyl halides as coupling partners. More importantly, the reaction proceeded smoothly with a large scale (> 10 g, > 90% yield), which further highlighted the potential application of this selenation strategy.
2022, 33(9): 4306-4312
doi: 10.1016/j.cclet.2021.12.052
Abstract:
Ten novel butterfly-shaped dithienobenzosilole-based luminogens, which are peripherally installed with a variety of substituents including hydrogen, phenyl and substituted phenyl groups, have been readily prepared via an iodine-induced intramolecular electrophilic double-cyclisation reaction and subsequent deiodination or coupling reactions. The optical and electrochemical properties of these compounds were systematically investigated to clarify the relationships between their structures and properties, supported by theoretical calculations. These compounds exhibit deep-blue to sky-blue emissions and high photoluminescence quantum yields up to 0.84 in solution and solid states which are regulated by the functional blades and their steric hindrance on the α– and β–positions of thiophene rings. Their high thermal- and photo- stabilities have been revealed and mainly attributed to the dithienobenzosilole core.
Ten novel butterfly-shaped dithienobenzosilole-based luminogens, which are peripherally installed with a variety of substituents including hydrogen, phenyl and substituted phenyl groups, have been readily prepared via an iodine-induced intramolecular electrophilic double-cyclisation reaction and subsequent deiodination or coupling reactions. The optical and electrochemical properties of these compounds were systematically investigated to clarify the relationships between their structures and properties, supported by theoretical calculations. These compounds exhibit deep-blue to sky-blue emissions and high photoluminescence quantum yields up to 0.84 in solution and solid states which are regulated by the functional blades and their steric hindrance on the α– and β–positions of thiophene rings. Their high thermal- and photo- stabilities have been revealed and mainly attributed to the dithienobenzosilole core.
2022, 33(9): 4313-4316
doi: 10.1016/j.cclet.2022.01.052
Abstract:
To develop efficient concerted companion (CC) dyes for fabricating high-performance DSSCs, three organic dyes XL1-XL3 have been designed by varying the position and number of the β-hexylthiophene (HT) bridges, and these organic dye units are covalently linked with our previously reported porphyrin dye XW10 to construct the corresponding CC dyes XW74-XW76. Among the organic dyes, XL3 contains two β-hexylthiophene units at both the donor and acceptor parts and thus possesses stronger light-harvesting capability in the green light region. Because of the most complementary absorption between XL3 and XW10 as well as the excellent photovoltaic behavior of the individual XL3 dye, the corresponding CC dye XW76 affords the best PCE (10.78%) among all the CC dyes. Upon coadsorption with CDCA, XW76 affords a highest PCE of 11.35%, which outperforms the previous cosensitization system of XW10+WS-5. This work provides an approach for developing efficient DSSCs based on CC dyes composed of an organic dye unit with suitable π spacers inserted at appropriate positions.
To develop efficient concerted companion (CC) dyes for fabricating high-performance DSSCs, three organic dyes XL1-XL3 have been designed by varying the position and number of the β-hexylthiophene (HT) bridges, and these organic dye units are covalently linked with our previously reported porphyrin dye XW10 to construct the corresponding CC dyes XW74-XW76. Among the organic dyes, XL3 contains two β-hexylthiophene units at both the donor and acceptor parts and thus possesses stronger light-harvesting capability in the green light region. Because of the most complementary absorption between XL3 and XW10 as well as the excellent photovoltaic behavior of the individual XL3 dye, the corresponding CC dye XW76 affords the best PCE (10.78%) among all the CC dyes. Upon coadsorption with CDCA, XW76 affords a highest PCE of 11.35%, which outperforms the previous cosensitization system of XW10+WS-5. This work provides an approach for developing efficient DSSCs based on CC dyes composed of an organic dye unit with suitable π spacers inserted at appropriate positions.
2022, 33(9): 4317-4320
doi: 10.1016/j.cclet.2022.01.009
Abstract:
Although the construction of specific functional crystalline materials is still challenging, the multi-component molecular assembly has become a key solution for the design of functional materials. Here, we report a hydrogen-bonded organic framework (HOF) material FJU-360 constructed from disodium 6-hydroxy-5-[(4-sulfophenyl)azo]-2-naphthalenesulfonate (SSY) and terephthalimidamide. The charge-assisted hydrogen bonding between amidinium and sulfonate makes FJU-360 produce much stronger fluorescence than SSY, and can be used as a luminescence sensor to rapidly quench aniline through luminescence quenching. FJU-360 is sensitive and highly selective for the detection of aniline, and the detection limit reached 3.2 nmol/L, which is the lowest value reported currently. The mechanism of aniline response was analyzed through the aniline@FJU-360 single crystal structure, and the luminescence mechanism was clarified through density function theory calculations. This work is an important step towards the rational synthesis and assembly of sensing materials.
Although the construction of specific functional crystalline materials is still challenging, the multi-component molecular assembly has become a key solution for the design of functional materials. Here, we report a hydrogen-bonded organic framework (HOF) material FJU-360 constructed from disodium 6-hydroxy-5-[(4-sulfophenyl)azo]-2-naphthalenesulfonate (SSY) and terephthalimidamide. The charge-assisted hydrogen bonding between amidinium and sulfonate makes FJU-360 produce much stronger fluorescence than SSY, and can be used as a luminescence sensor to rapidly quench aniline through luminescence quenching. FJU-360 is sensitive and highly selective for the detection of aniline, and the detection limit reached 3.2 nmol/L, which is the lowest value reported currently. The mechanism of aniline response was analyzed through the aniline@FJU-360 single crystal structure, and the luminescence mechanism was clarified through density function theory calculations. This work is an important step towards the rational synthesis and assembly of sensing materials.
2022, 33(9): 4321-4325
doi: 10.1016/j.cclet.2022.01.024
Abstract:
Corneal wound closure for surgical eye surgeries or accidents is typically performed to prevent pathogens from the sterile intraocular environment and avoid potential postoperative complications. Tissue adhesives are increasingly employed for corneal wound closure with superior treatment efficiency and less adverse effects. In this study, we successfully develop a novel corneal adhesive based on functionally coupled PEG-lysozyme (PEG-LZ) hydrogels for wound closure after surgical eye surgeries. PEG-LZ hydrogels have plenty of micropores and gradually decreased pore size with increasing concentration from 10%, 15% to 20% (w/v), in which PEG-LZ (15%) represents the suitable pH value, gelation time and elastic modulus. PEG-LZ hydrogels have no in vitro cytotoxicity and excellent ex vivo wound closure effectiveness in porcine eyes. The in vivo wound sealant in rabbit eyes by PEG-LZ hydrogels presents a superior therapeutic effect compared with the conventional methods of stromal hydration and suture, in terms of the wound closure percent, mean corneal thickness, percent of wound gaping, and the Descemet membrane detachment. PEG-LZ hydrogels do not induce obvious histological pathology changes. The PEG-LZ corneal adhesive is considered as a tissue adhesive alternative for wound closure after surgical eye surgeries.
Corneal wound closure for surgical eye surgeries or accidents is typically performed to prevent pathogens from the sterile intraocular environment and avoid potential postoperative complications. Tissue adhesives are increasingly employed for corneal wound closure with superior treatment efficiency and less adverse effects. In this study, we successfully develop a novel corneal adhesive based on functionally coupled PEG-lysozyme (PEG-LZ) hydrogels for wound closure after surgical eye surgeries. PEG-LZ hydrogels have plenty of micropores and gradually decreased pore size with increasing concentration from 10%, 15% to 20% (w/v), in which PEG-LZ (15%) represents the suitable pH value, gelation time and elastic modulus. PEG-LZ hydrogels have no in vitro cytotoxicity and excellent ex vivo wound closure effectiveness in porcine eyes. The in vivo wound sealant in rabbit eyes by PEG-LZ hydrogels presents a superior therapeutic effect compared with the conventional methods of stromal hydration and suture, in terms of the wound closure percent, mean corneal thickness, percent of wound gaping, and the Descemet membrane detachment. PEG-LZ hydrogels do not induce obvious histological pathology changes. The PEG-LZ corneal adhesive is considered as a tissue adhesive alternative for wound closure after surgical eye surgeries.
2022, 33(9): 4326-4330
doi: 10.1016/j.cclet.2021.12.031
Abstract:
Solid-state electrolytes (SSEs) with high ionic conductivity, mechanical stability, and high thermal stability, as well as the stringent requirement of application in high-temperature fuel cells and lithium-ion batteries is receiving increasing attention. Polymer nanocomposites (PNCs), combining the advantages of inorganic materials with those of polymeric materials, offer numerous opportunities for SSEs design. In this work, we report a facile and general one-pot approach based on polymerization-induced microphase separation (PIMS) to generate PNCs with bi-continuous microphases. This synthetic strategy transforms a homogeneous liquid precursor consisting of polyoxometalates (POMs, H3PW12O40, Li7[V15O36(CO3)]), poly(ethylene glycol) (PEG) macro-chain-transfer agent, styrene and divinylbenzene monomers, into a robust and transparent monolith. The resulting POMs are uniformly dispersed in the PEG block (PEG/POM) to form a conducting pathway that successfully realizes the effective transfer of protons and lithium ions, while the highly cross-linked polystyrene domains (P(S-co-DVB)) as mechanical support provide outstanding mechanical properties and thermal stability. As the POM loading ratio up to 35 wt%, the proton conductivity of nanocomposite reaches as high as 5.99 × 10-4 S/cm at 100 ℃ in anhydrous environment, which effectively promotes proton transfer under extreme environments. This study broadens the application of fuel cells and lithium-ion batteries in extreme environments.
Solid-state electrolytes (SSEs) with high ionic conductivity, mechanical stability, and high thermal stability, as well as the stringent requirement of application in high-temperature fuel cells and lithium-ion batteries is receiving increasing attention. Polymer nanocomposites (PNCs), combining the advantages of inorganic materials with those of polymeric materials, offer numerous opportunities for SSEs design. In this work, we report a facile and general one-pot approach based on polymerization-induced microphase separation (PIMS) to generate PNCs with bi-continuous microphases. This synthetic strategy transforms a homogeneous liquid precursor consisting of polyoxometalates (POMs, H3PW12O40, Li7[V15O36(CO3)]), poly(ethylene glycol) (PEG) macro-chain-transfer agent, styrene and divinylbenzene monomers, into a robust and transparent monolith. The resulting POMs are uniformly dispersed in the PEG block (PEG/POM) to form a conducting pathway that successfully realizes the effective transfer of protons and lithium ions, while the highly cross-linked polystyrene domains (P(S-co-DVB)) as mechanical support provide outstanding mechanical properties and thermal stability. As the POM loading ratio up to 35 wt%, the proton conductivity of nanocomposite reaches as high as 5.99 × 10-4 S/cm at 100 ℃ in anhydrous environment, which effectively promotes proton transfer under extreme environments. This study broadens the application of fuel cells and lithium-ion batteries in extreme environments.
2022, 33(9): 4331-4334
doi: 10.1016/j.cclet.2021.12.032
Abstract:
Transforming immature DCs into mature state to activate cellular immunity is a critical step in initiating immunoprophylaxis and immunotherapy. Lipopolysaccharides (LPS) can promote DCs maturation by binding receptor on DCs surface, but their clinical application is limited due to biological toxicity. Although many LPS analogues have been developed, complex synthesis and purification hinder their practical application. Here, we propose a novel and simple strategy to synthesize LPS analogues with adjustable structural units. Using monomer units similar to the key functional groups of LPS, we synthesize LPS analogues with different group ratios by RAFT polymerization. The obtained analogues have little negative effect on cell viability. Compared with LPS, the analogues show greater promoting effect on DCs maturation. And the analogues can be applied to different scenarios since the degrees of promoting DCs maturation by LPS analogues with different group ratios are different. This strategy provides a new direction for synthesizing LPS analogues, and it has the potential to produce LPS analogues on a large scale with tunable promoting DCs maturation effect.
Transforming immature DCs into mature state to activate cellular immunity is a critical step in initiating immunoprophylaxis and immunotherapy. Lipopolysaccharides (LPS) can promote DCs maturation by binding receptor on DCs surface, but their clinical application is limited due to biological toxicity. Although many LPS analogues have been developed, complex synthesis and purification hinder their practical application. Here, we propose a novel and simple strategy to synthesize LPS analogues with adjustable structural units. Using monomer units similar to the key functional groups of LPS, we synthesize LPS analogues with different group ratios by RAFT polymerization. The obtained analogues have little negative effect on cell viability. Compared with LPS, the analogues show greater promoting effect on DCs maturation. And the analogues can be applied to different scenarios since the degrees of promoting DCs maturation by LPS analogues with different group ratios are different. This strategy provides a new direction for synthesizing LPS analogues, and it has the potential to produce LPS analogues on a large scale with tunable promoting DCs maturation effect.
2022, 33(9): 4335-4338
doi: 10.1016/j.cclet.2022.01.022
Abstract:
Nuclear magnetic resonance (NMR) spectroscopy has provided many powerful tools for the study of dynamic processes. Among the reported methods, chemical exchange saturation transfer (CEST) is more suitable for systems with slow exchange rates, and there will be promising in the detection and dynamic mechanism of metastable substances. It has been widely used in magnetic resonance imaging (MRI), however whether it is applicable in the field of chemical kinetics needs more examples. Here we studied, as a proof of concept, the kinetics of the slow chemical exchange between the two N-methyl protons of N, N-dimethylacetylamide (DMA), exploiting QUantifying Exchange using Z-spectrum (QUEZS) and QUantifying Exchange using Saturation Time (QUEST) methods. It turned out that both of QUEZS and QUEST could give the corresponding exchange rates, showcasing the capability of this method to provide accurate kinetic data under a range of temperatures. Our results clearly demonstrated the reliability of CEST-based techniques as a tool for dynamic kinetics by NMR.
Nuclear magnetic resonance (NMR) spectroscopy has provided many powerful tools for the study of dynamic processes. Among the reported methods, chemical exchange saturation transfer (CEST) is more suitable for systems with slow exchange rates, and there will be promising in the detection and dynamic mechanism of metastable substances. It has been widely used in magnetic resonance imaging (MRI), however whether it is applicable in the field of chemical kinetics needs more examples. Here we studied, as a proof of concept, the kinetics of the slow chemical exchange between the two N-methyl protons of N, N-dimethylacetylamide (DMA), exploiting QUantifying Exchange using Z-spectrum (QUEZS) and QUantifying Exchange using Saturation Time (QUEST) methods. It turned out that both of QUEZS and QUEST could give the corresponding exchange rates, showcasing the capability of this method to provide accurate kinetic data under a range of temperatures. Our results clearly demonstrated the reliability of CEST-based techniques as a tool for dynamic kinetics by NMR.
2022, 33(9): 4339-4344
doi: 10.1016/j.cclet.2022.01.036
Abstract:
Riboflavin (RF, vitamin B2) is an essential vitamin and has been considered as a promising natural photosensitizer for photodynamic therapy (PDT). However, further exploration of RF in antitumor application was limited by its poor cellular uptake. In this study, using cell-penetrating peptides Arg8, (Cha-Arg)3 and small molecule triphenylphosphine (TPP) as delivery compounds, three RF conjugates were prepared to increase the accumulation of RF in cells, termed as Arg8-RF, (Cha-Arg)3-RF and TPP-RF, respectively. Compared with TPP-RF and Arg8-RF, (Cha-Arg)3-RF exhibited better cell internalization and stronger cytotoxicity against HeLa cells upon exposure to blue light. Further researches proved that (Cha-Arg)3-RF generated reactive oxygen species (ROS) under irradiation, which could indiscriminately destroy endogenous proteins and mitochondria, ultimately inducing cell death. This work provides a new approach to explore RF as a natural photosensitizer for antitumor photodynamic therapy.
Riboflavin (RF, vitamin B2) is an essential vitamin and has been considered as a promising natural photosensitizer for photodynamic therapy (PDT). However, further exploration of RF in antitumor application was limited by its poor cellular uptake. In this study, using cell-penetrating peptides Arg8, (Cha-Arg)3 and small molecule triphenylphosphine (TPP) as delivery compounds, three RF conjugates were prepared to increase the accumulation of RF in cells, termed as Arg8-RF, (Cha-Arg)3-RF and TPP-RF, respectively. Compared with TPP-RF and Arg8-RF, (Cha-Arg)3-RF exhibited better cell internalization and stronger cytotoxicity against HeLa cells upon exposure to blue light. Further researches proved that (Cha-Arg)3-RF generated reactive oxygen species (ROS) under irradiation, which could indiscriminately destroy endogenous proteins and mitochondria, ultimately inducing cell death. This work provides a new approach to explore RF as a natural photosensitizer for antitumor photodynamic therapy.
2022, 33(9): 4345-4349
doi: 10.1016/j.cclet.2021.12.065
Abstract:
Phosphorylated di-, tri- and tetra-saccharides of β-1, 2-mannan antigen derived from Candida albicans (C. albicans) cell wall were synthesized and covalently conjugated with keyhole limpet hemocyanin (KLH) and human serum albumin (HSA) via a bifunctional linker under mild conditions. The semi-synthetic β-1, 2-mannoside–KLH conjugates were evaluated for the immunization of BALB/c mice. The ELISA results revealed that all three conjugates could elicit high levels of specific IgG antibodies and the acquired antisera could effectively identify the β-1, 2-mannan epitope. Furthermore, the immunofluorescence and flow cytometry assays also uncovered that the induced antibodies, especially that obtained from immunization with β-1, 2-mannotriose–KLH conjugate (1b), could bind well to fungi cell. Eventually, the structure–immunogenicity relationship analysis of β-mannan showed that the length of oligo-β-mannoses had a big impact on their immunogenicity and β-1, 2-mannotriose showed the strongest immunogenicity. The results suggested the great potential of β-1, 2-mannotriose–KLH conjugate as an antifungal vaccine candidate.
Phosphorylated di-, tri- and tetra-saccharides of β-1, 2-mannan antigen derived from Candida albicans (C. albicans) cell wall were synthesized and covalently conjugated with keyhole limpet hemocyanin (KLH) and human serum albumin (HSA) via a bifunctional linker under mild conditions. The semi-synthetic β-1, 2-mannoside–KLH conjugates were evaluated for the immunization of BALB/c mice. The ELISA results revealed that all three conjugates could elicit high levels of specific IgG antibodies and the acquired antisera could effectively identify the β-1, 2-mannan epitope. Furthermore, the immunofluorescence and flow cytometry assays also uncovered that the induced antibodies, especially that obtained from immunization with β-1, 2-mannotriose–KLH conjugate (1b), could bind well to fungi cell. Eventually, the structure–immunogenicity relationship analysis of β-mannan showed that the length of oligo-β-mannoses had a big impact on their immunogenicity and β-1, 2-mannotriose showed the strongest immunogenicity. The results suggested the great potential of β-1, 2-mannotriose–KLH conjugate as an antifungal vaccine candidate.
2022, 33(9): 4350-4356
doi: 10.1016/j.cclet.2021.11.043
Abstract:
Reasonable construction of sulfur host with high conductivity, large sulfur storage gap, strong chemical adsorption, and fast oxidation–reduction kinetics of polysulfide is very significant for its practical use in lithium-sulfur batteries (LSBs). In this paper, the surface modification of MIL-88A(Fe) is carried out by Dawson-type polyoxometalate (POM), and a hollow capsule shell material with P2W18, Fe3O4, and C components is synthesized by the subsequent carbonization process. When applied as the sulfur host, the hollow capsule shell material can efficiently improve the conductivity of sulfur electrode and restrain the volumetric change of active sulfur while charging and discharging. On this foundation, electrochemical analysis and density functional theory (DFT) calculation show that the P2W18 on the outer layer of the capsule shell have effective electrocatalytic activity and potent chemical bond on the lithium polysulfides (LiPSs), which is helpful to block the shuttle effect. Therefore, the as-assembled LSBs display the outstanding specific capacity and prominent cycle stability. Specifically, it delivers an excellent reversible capacity of 1063 mAh/g after 100 cycles of charge–discharge at a rate of 0.5 C, accounting for a preservation by 96% in comparison to that of the initial cycle. Moreover, even after 2000 cycles at 1 C, the reversible specific capacity of 585 mAh/g can still be maintained with an average decay rate of only 0.021%.
Reasonable construction of sulfur host with high conductivity, large sulfur storage gap, strong chemical adsorption, and fast oxidation–reduction kinetics of polysulfide is very significant for its practical use in lithium-sulfur batteries (LSBs). In this paper, the surface modification of MIL-88A(Fe) is carried out by Dawson-type polyoxometalate (POM), and a hollow capsule shell material with P2W18, Fe3O4, and C components is synthesized by the subsequent carbonization process. When applied as the sulfur host, the hollow capsule shell material can efficiently improve the conductivity of sulfur electrode and restrain the volumetric change of active sulfur while charging and discharging. On this foundation, electrochemical analysis and density functional theory (DFT) calculation show that the P2W18 on the outer layer of the capsule shell have effective electrocatalytic activity and potent chemical bond on the lithium polysulfides (LiPSs), which is helpful to block the shuttle effect. Therefore, the as-assembled LSBs display the outstanding specific capacity and prominent cycle stability. Specifically, it delivers an excellent reversible capacity of 1063 mAh/g after 100 cycles of charge–discharge at a rate of 0.5 C, accounting for a preservation by 96% in comparison to that of the initial cycle. Moreover, even after 2000 cycles at 1 C, the reversible specific capacity of 585 mAh/g can still be maintained with an average decay rate of only 0.021%.
2022, 33(9): 4357-4362
doi: 10.1016/j.cclet.2021.11.084
Abstract:
Selective cleavage of robust C−C bonds to harvest value-added aromatic oxygenates is an intriguing but challenging task in lignin depolymerization. Photocatalysis is a promising technology with the advantages of mild reaction conditions and strong sustainability. Herein, we show a novel urchin-like Nb2O5 hollow microsphere (U-Nb2O5 HM), prepared by one-pot hydrothermal method, are highly active and selective for Cα−Cβ bond cleavage of lignin β-O-4 model compounds under mild conditions, achieving 94% substrate conversion and 96% C−C bond cleavage selectivity. Systematic experimental studies and density functional theory (DFT) calculations revealed that the superior performance of U-Nb2O5 HMs arises from more exposed active sites, more efficient free charge separation and the active (001) facet, which facilitates the activation of Cβ−H bond of lignin models and generate key Cβ radical intermediates by photogenerated holes, further inducing the Cα−Cβ bond cleavage to produce aromatic oxygenates. This work could provide some suggestions for the fabrication of hierarchical photocatalysts in the lignin depolymerization system.
Selective cleavage of robust C−C bonds to harvest value-added aromatic oxygenates is an intriguing but challenging task in lignin depolymerization. Photocatalysis is a promising technology with the advantages of mild reaction conditions and strong sustainability. Herein, we show a novel urchin-like Nb2O5 hollow microsphere (U-Nb2O5 HM), prepared by one-pot hydrothermal method, are highly active and selective for Cα−Cβ bond cleavage of lignin β-O-4 model compounds under mild conditions, achieving 94% substrate conversion and 96% C−C bond cleavage selectivity. Systematic experimental studies and density functional theory (DFT) calculations revealed that the superior performance of U-Nb2O5 HMs arises from more exposed active sites, more efficient free charge separation and the active (001) facet, which facilitates the activation of Cβ−H bond of lignin models and generate key Cβ radical intermediates by photogenerated holes, further inducing the Cα−Cβ bond cleavage to produce aromatic oxygenates. This work could provide some suggestions for the fabrication of hierarchical photocatalysts in the lignin depolymerization system.
2022, 33(9): 4363-4366
doi: 10.1016/j.cclet.2021.12.036
Abstract:
The tuning of olefin-polymerization catalyst properties through ligand modifications is efficient but requires complicated and costly syntheses. In this contribution, a simple Bu2Mg-based cocatalyst strategy is designed that can simultaneously enhance the catalytic properties (activity, thermal stability, polymer molecular weight, branching density, melting point, etc.) of various nickel catalysts (α-diimine nickel, pyridine imine nickel and iminopyridine-N-oxide nickel) in ethylene polymerization, and enable great product morphology control. For example, a simple α-diimine nickel catalyst can demonstrate polymerization activity of up to 1.29 × 107 g mol−1 h−1 and molecular weight of up to 1.90 × 106 g/mol in the presence of Bu2Mg cocatalyst. The resulting polyethylenes exhibit excellent mechanical properties, with tensile stress of up to 47.4 MPa and strain of up to 1020%. This cocatalyst strategy is generally applicable to different nickel catalysts, and can lead to property enhancement in ethylene copolymerization with a series of polar comonomers such as methyl 10-undecylenate, 10-undecylenic acid and 10-undecenol.
The tuning of olefin-polymerization catalyst properties through ligand modifications is efficient but requires complicated and costly syntheses. In this contribution, a simple Bu2Mg-based cocatalyst strategy is designed that can simultaneously enhance the catalytic properties (activity, thermal stability, polymer molecular weight, branching density, melting point, etc.) of various nickel catalysts (α-diimine nickel, pyridine imine nickel and iminopyridine-N-oxide nickel) in ethylene polymerization, and enable great product morphology control. For example, a simple α-diimine nickel catalyst can demonstrate polymerization activity of up to 1.29 × 107 g mol−1 h−1 and molecular weight of up to 1.90 × 106 g/mol in the presence of Bu2Mg cocatalyst. The resulting polyethylenes exhibit excellent mechanical properties, with tensile stress of up to 47.4 MPa and strain of up to 1020%. This cocatalyst strategy is generally applicable to different nickel catalysts, and can lead to property enhancement in ethylene copolymerization with a series of polar comonomers such as methyl 10-undecylenate, 10-undecylenic acid and 10-undecenol.
2022, 33(9): 4367-4374
doi: 10.1016/j.cclet.2021.12.028
Abstract:
Rational design and building of high efficiency, secure and inexpensive electrocatalyst is a pressing demand and performance to promote sustainable improvement of hydrogen energy. The bifunctional electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution response (HER) with high catalytic performance and steadiness in the equal electrolyte are extra treasured and meaningful. Herein, a unique three-dimensional (3D) structure electrocatalyst for NiCo2S4 growing on the flower-like NiFeP was designed and synthesized in this study. The results show that the flower-like NiCo2S4/NiFeP/NF composite electrocatalyst has large specific surface area, appropriate electrical conductivity, and greater lively websites uncovered in the three-dimensional structure, and affords extraordinary electrocatalytic overall performance for the ordinary water splitting. In alkaline solution, the OER and HER overpotentials of NiCo2S4/NiFeP/NF only need 293 mV and 205 mV overpotential to provide the current densities of 100 mA/cm2 and 50 mA/cm2, respectively. This high electrocatalytic activity exceeds the catalytic activity of most nickel-iron based electrocatalysts for OER and HER process. Accordingly, the optimized NiCo2S4/NiFeP/NF sample has higher stability (24 h) at 1.560 and 10 mA/cm2, which extensively speeds up the overall water splitting process. In view of the above performance, this work offers a fine approach for the further improvement of low fee and excessive effectivity electrocatalyst.
Rational design and building of high efficiency, secure and inexpensive electrocatalyst is a pressing demand and performance to promote sustainable improvement of hydrogen energy. The bifunctional electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution response (HER) with high catalytic performance and steadiness in the equal electrolyte are extra treasured and meaningful. Herein, a unique three-dimensional (3D) structure electrocatalyst for NiCo2S4 growing on the flower-like NiFeP was designed and synthesized in this study. The results show that the flower-like NiCo2S4/NiFeP/NF composite electrocatalyst has large specific surface area, appropriate electrical conductivity, and greater lively websites uncovered in the three-dimensional structure, and affords extraordinary electrocatalytic overall performance for the ordinary water splitting. In alkaline solution, the OER and HER overpotentials of NiCo2S4/NiFeP/NF only need 293 mV and 205 mV overpotential to provide the current densities of 100 mA/cm2 and 50 mA/cm2, respectively. This high electrocatalytic activity exceeds the catalytic activity of most nickel-iron based electrocatalysts for OER and HER process. Accordingly, the optimized NiCo2S4/NiFeP/NF sample has higher stability (24 h) at 1.560 and 10 mA/cm2, which extensively speeds up the overall water splitting process. In view of the above performance, this work offers a fine approach for the further improvement of low fee and excessive effectivity electrocatalyst.
2022, 33(9): 4375-4379
doi: 10.1016/j.cclet.2021.12.027
Abstract:
Relying on the electron energy loss spectrum (EELS) of metallic elements to obtain microstructure analysis is an investigation method of the reaction mechanisms of transition metal oxides (TMOs) in catalysis, energy storage and conversion. However, the low signal from K shell owing to insufficient electron beam energy, and the complicated electronic structure in L shell of the metal element restrict the analysis of the coordination environment of the TMOs. Herein, density functional theory (DFT) calculation, Fourier transform (FT) and wavelet transform (WT) were employed to probe the relationship between the four individual peaks in O K-edge spectra of iron oxides and the microstructure information (chemical bonds and atomic coordination). The findings show that the peak amplitude ration is in a linear correlation with the valence state of Fe element, and that the coordination number obtained by radial distribution function (RDF) is favorably linearly correlative with that from the standard coordination structure model. As a result, the quantitative analysis on the change of valence state and atomic coordination in microstructure can be realized by EELS O K-edge spectra. This study establishes EELS O K-edge spectrum as a promising pathway to quantitatively analyze the valence state and atomic coordination information of TMOs, and offers an effective method to conduct microstructure analysis via the EELS spectra of the non-metal element.
Relying on the electron energy loss spectrum (EELS) of metallic elements to obtain microstructure analysis is an investigation method of the reaction mechanisms of transition metal oxides (TMOs) in catalysis, energy storage and conversion. However, the low signal from K shell owing to insufficient electron beam energy, and the complicated electronic structure in L shell of the metal element restrict the analysis of the coordination environment of the TMOs. Herein, density functional theory (DFT) calculation, Fourier transform (FT) and wavelet transform (WT) were employed to probe the relationship between the four individual peaks in O K-edge spectra of iron oxides and the microstructure information (chemical bonds and atomic coordination). The findings show that the peak amplitude ration is in a linear correlation with the valence state of Fe element, and that the coordination number obtained by radial distribution function (RDF) is favorably linearly correlative with that from the standard coordination structure model. As a result, the quantitative analysis on the change of valence state and atomic coordination in microstructure can be realized by EELS O K-edge spectra. This study establishes EELS O K-edge spectrum as a promising pathway to quantitatively analyze the valence state and atomic coordination information of TMOs, and offers an effective method to conduct microstructure analysis via the EELS spectra of the non-metal element.
2022, 33(9): 4380-4384
doi: 10.1016/j.cclet.2021.12.034
Abstract:
Carbon dioxide electrochemical reduction (CO2RR) has been recognized as an efficient way to mitigate CO2 emissions and alleviate the pressure on global warming and associated environmental consequences. Gold (Au) is reported as stable and active electrocatalysts to convert CO2 to CO at low overpotential due to its moderate adsorption strength of *COOH and *CO. The request for improved catalytic performance, however, is motivated by current unsatisfied catalytic selectivity because of the side hydrogen evolution reaction. In this context, the design of Au based binary catalysts that can boost CO selectivity is of great interest. In the present work, we report that Au nanoparticles can be feasibly dispersed and anchored on silicon nanowires to form Au-Si binary nanomaterials. The Au-Si may stably drive CO2RR with a CO Faraday efficiency of 95.6% at −0.6 V vs. RHE in 0.5 mol/L KHCO3 solution. Such selectivity outperforms Au particles by up to 61%. Controlled experiments illustrate that such catalytic enhancement can chiefly be ascribed to electronic effects of binary catalysts. Theoretical calculations reveal that spontaneously produced silicon oxide may not only inhibit hydrogen evolution reaction, but also stabilize the key intermediate *COOH in CO formation.
Carbon dioxide electrochemical reduction (CO2RR) has been recognized as an efficient way to mitigate CO2 emissions and alleviate the pressure on global warming and associated environmental consequences. Gold (Au) is reported as stable and active electrocatalysts to convert CO2 to CO at low overpotential due to its moderate adsorption strength of *COOH and *CO. The request for improved catalytic performance, however, is motivated by current unsatisfied catalytic selectivity because of the side hydrogen evolution reaction. In this context, the design of Au based binary catalysts that can boost CO selectivity is of great interest. In the present work, we report that Au nanoparticles can be feasibly dispersed and anchored on silicon nanowires to form Au-Si binary nanomaterials. The Au-Si may stably drive CO2RR with a CO Faraday efficiency of 95.6% at −0.6 V vs. RHE in 0.5 mol/L KHCO3 solution. Such selectivity outperforms Au particles by up to 61%. Controlled experiments illustrate that such catalytic enhancement can chiefly be ascribed to electronic effects of binary catalysts. Theoretical calculations reveal that spontaneously produced silicon oxide may not only inhibit hydrogen evolution reaction, but also stabilize the key intermediate *COOH in CO formation.
2022, 33(9): 4385-4388
doi: 10.1016/j.cclet.2021.12.039
Abstract:
The BiOCl (BOC) synthesized by the water bath heating method was treated with sodium borohydride (NaBH4) to introduce oxygen vacancies (OVs). At the same time, Au nanoparticles were loaded to prepare a series of Au/BiOCl samples with different ratios. OVs and Au nanoparticles can promote the light absorption of host photocatalyst in the visible region. The calculated work function of BiOCl and Au can verify the existence of Ohmic contact between the interface of them, which is conducive to the separation of charge carriers. Through a series of photoelectric tests, it was verified experimentally that the separation of charge carriers is indeed enhanced. The high-energy hot electrons produced by Au under the surface plasmon resonance (SPR) effect can increase the counts of electrons to participate in the CO2 reduction reaction. Especially for 1.0%-Au/BOC, the yields of CO can reach 43.16 µmol g−1 h−1, which is 6.6 times more than that of BOC. Therefore, loading precious metal on semiconductors is an effective strategy to promote the photocatalytic performance of CO2 reduction reactions.
The BiOCl (BOC) synthesized by the water bath heating method was treated with sodium borohydride (NaBH4) to introduce oxygen vacancies (OVs). At the same time, Au nanoparticles were loaded to prepare a series of Au/BiOCl samples with different ratios. OVs and Au nanoparticles can promote the light absorption of host photocatalyst in the visible region. The calculated work function of BiOCl and Au can verify the existence of Ohmic contact between the interface of them, which is conducive to the separation of charge carriers. Through a series of photoelectric tests, it was verified experimentally that the separation of charge carriers is indeed enhanced. The high-energy hot electrons produced by Au under the surface plasmon resonance (SPR) effect can increase the counts of electrons to participate in the CO2 reduction reaction. Especially for 1.0%-Au/BOC, the yields of CO can reach 43.16 µmol g−1 h−1, which is 6.6 times more than that of BOC. Therefore, loading precious metal on semiconductors is an effective strategy to promote the photocatalytic performance of CO2 reduction reactions.
2022, 33(9): 4389-4394
doi: 10.1016/j.cclet.2021.12.024
Abstract:
In this paper, three new polyoxometalates (POM)-based metal–organic complexes constructed from a new semi-rigid organic ligand N,N'-bis(4-pyrimidinecarboxamido)-1,2-cyclohexane (4-bpmah) H2[Cu(4-bpmah)2(SiMo12O40)(H2O)2]·2H2O (1), H[Cu(4-bpmah)2(PMo12O40)(H2O)2]·2H2O (2) and [Cu(4-bpmah)(H2O)2]·[Cu2(TeMo6O24)(H2O)10]·4H2O (3) were synthesized by hydrothermal method. Single crystal X-ray analyses showed that complexes 1 and 2 were isostructural, in which the isolated Keggin-type [SiMo12O40]4–/[PMo12O40]3– anions and [Cu(4-bpmah)2(H2O)2]2n+ units were expanded into 3D supramolecular structures through hydrogen bond interactions. In complex 3, the 1D [Cu(4-bpmah)(H2O)2]2n+ metal–organic chains and isolated [Cu2(TeMo6O24)(H2O)10]2n– units were expanded into a 3D supramolecular framework by the hydrogen bond interactions. In this paper, carbon cloth working electrodes composited by the title complexes (1/CC, 2/CC and 3/CC) were prepared and used as electrodes for supercapacitors. The performance of supercapacitors as well as the influence of electrolyte solution and title complexes quality load on the performance of supercapacitors were studied. Furthermore, the electrochemistry and electrocatalytic behaviors of complexes 1–3 bulk-modified carbon paste electrodes (1-CPE, 2-CPE and 3-CPE) toward the reduction of KBrO3, KNO2, Cr(Ⅵ), as well as their sensing behaviors on Cr(Ⅵ) were investigated.
In this paper, three new polyoxometalates (POM)-based metal–organic complexes constructed from a new semi-rigid organic ligand N,N'-bis(4-pyrimidinecarboxamido)-1,2-cyclohexane (4-bpmah) H2[Cu(4-bpmah)2(SiMo12O40)(H2O)2]·2H2O (1), H[Cu(4-bpmah)2(PMo12O40)(H2O)2]·2H2O (2) and [Cu(4-bpmah)(H2O)2]·[Cu2(TeMo6O24)(H2O)10]·4H2O (3) were synthesized by hydrothermal method. Single crystal X-ray analyses showed that complexes 1 and 2 were isostructural, in which the isolated Keggin-type [SiMo12O40]4–/[PMo12O40]3– anions and [Cu(4-bpmah)2(H2O)2]2n+ units were expanded into 3D supramolecular structures through hydrogen bond interactions. In complex 3, the 1D [Cu(4-bpmah)(H2O)2]2n+ metal–organic chains and isolated [Cu2(TeMo6O24)(H2O)10]2n– units were expanded into a 3D supramolecular framework by the hydrogen bond interactions. In this paper, carbon cloth working electrodes composited by the title complexes (1/CC, 2/CC and 3/CC) were prepared and used as electrodes for supercapacitors. The performance of supercapacitors as well as the influence of electrolyte solution and title complexes quality load on the performance of supercapacitors were studied. Furthermore, the electrochemistry and electrocatalytic behaviors of complexes 1–3 bulk-modified carbon paste electrodes (1-CPE, 2-CPE and 3-CPE) toward the reduction of KBrO3, KNO2, Cr(Ⅵ), as well as their sensing behaviors on Cr(Ⅵ) were investigated.
2022, 33(9): 4395-4399
doi: 10.1016/j.cclet.2021.12.023
Abstract:
The visible-light-induced selective oxidation of ubiquitous C–H bonds into valuable C=O bonds under aerobic conditions is one of the most attractive approaches for the construction of carbonyl-containing molecules. In this work, two transition metal-containing Nb/W mixed-addendum POMs dimers with the formula of K2Na2H5[(Fe(H2O)4)3(P2W15Nb3O62)2]·24H2O (POM[Fe]) and K2Na3H4[(Cr(H2O)4)3(P2W15Nb3O62)2]·32H2O (POM[Cr]) have been synthesized and characterized by various analytical and spectral techniques. POM[Fe] was proved to be an efficient photocatalyst for benzylic C–H oxidation under visible light and using oxygen as an oxidant to produce the corresponding carbonyl complex in good yields. A plausible mechanism involving superoxide radical was proposed for the catalytic reaction. POM[Fe] showed good reusability in the recycling experiments. IR spectroscopy and XRD analysis indicate that POM[Fe] can retain its integrity after catalysis.
The visible-light-induced selective oxidation of ubiquitous C–H bonds into valuable C=O bonds under aerobic conditions is one of the most attractive approaches for the construction of carbonyl-containing molecules. In this work, two transition metal-containing Nb/W mixed-addendum POMs dimers with the formula of K2Na2H5[(Fe(H2O)4)3(P2W15Nb3O62)2]·24H2O (POM[Fe]) and K2Na3H4[(Cr(H2O)4)3(P2W15Nb3O62)2]·32H2O (POM[Cr]) have been synthesized and characterized by various analytical and spectral techniques. POM[Fe] was proved to be an efficient photocatalyst for benzylic C–H oxidation under visible light and using oxygen as an oxidant to produce the corresponding carbonyl complex in good yields. A plausible mechanism involving superoxide radical was proposed for the catalytic reaction. POM[Fe] showed good reusability in the recycling experiments. IR spectroscopy and XRD analysis indicate that POM[Fe] can retain its integrity after catalysis.
2022, 33(9): 4400-4404
doi: 10.1016/j.cclet.2021.12.021
Abstract:
Photo-assisted electrochemical technique provides a promising approach towards carcinogen chromium(Ⅵ) detection, which requires reasonable catalyst design. Herein, an unusual hexa-nuclear cadmium cluster functionalized reductive phosphomolybdate hybrid as photo-electrochemical sensor was designed and synthesized with formula of {[Cd(H2O)2]2[Cd(btmbp)]2}{Cd(P4Mo6O31H7)2}·20H2O (1) (btmbp= 4,4′-bis((1H-1,2,4-triazol-1-yl)methyl)biphenyl), in which the photoactive hexa-nuclear {Cd6} clusters cooperated with reductive phosphomolybdate [P4Mo6O31]12− endow the material with wide light absorption and remarkable redox activity, thus achieving efficient photo-assisted electrochemical Cr(Ⅵ) detection performance. Under visible-light assistance, the detection limit (LOD) and sensitivity of Cr(Ⅵ) is 4.17 nmol/L (0.225 ppb) and 226.32 µA L/µmol, which is apparently superior to the performance without photo-assistance (6.25 nmol/L and 106.95 µA L/µmol) and far satisfies the demands of world health organization (WHO) for potable water (50 ppb). Moreover, compound 1 showed prominent Cr(Ⅵ) detection performance in practical water samples together with remarkable anti-interference capacity and good electrochemical durability. This work provides an important guidance for designing efficient polyoxometalate-based crystalline sensors for Cr(Ⅵ) detection.
Photo-assisted electrochemical technique provides a promising approach towards carcinogen chromium(Ⅵ) detection, which requires reasonable catalyst design. Herein, an unusual hexa-nuclear cadmium cluster functionalized reductive phosphomolybdate hybrid as photo-electrochemical sensor was designed and synthesized with formula of {[Cd(H2O)2]2[Cd(btmbp)]2}{Cd(P4Mo6O31H7)2}·20H2O (1) (btmbp= 4,4′-bis((1H-1,2,4-triazol-1-yl)methyl)biphenyl), in which the photoactive hexa-nuclear {Cd6} clusters cooperated with reductive phosphomolybdate [P4Mo6O31]12− endow the material with wide light absorption and remarkable redox activity, thus achieving efficient photo-assisted electrochemical Cr(Ⅵ) detection performance. Under visible-light assistance, the detection limit (LOD) and sensitivity of Cr(Ⅵ) is 4.17 nmol/L (0.225 ppb) and 226.32 µA L/µmol, which is apparently superior to the performance without photo-assistance (6.25 nmol/L and 106.95 µA L/µmol) and far satisfies the demands of world health organization (WHO) for potable water (50 ppb). Moreover, compound 1 showed prominent Cr(Ⅵ) detection performance in practical water samples together with remarkable anti-interference capacity and good electrochemical durability. This work provides an important guidance for designing efficient polyoxometalate-based crystalline sensors for Cr(Ⅵ) detection.
2022, 33(9): 4405-4410
doi: 10.1016/j.cclet.2021.12.026
Abstract:
The development of a single analytical platform with different functions is highly desirable but remains a challenge at present. Here, a paper-based device based on fluorescent carbon dots (CDs) functionalized paper/MnO2 nanosheets (MnO2 NS) hybrid devices (PCD/NS) was proposed for single-device multi-function applications. MnO2 NS functioned as a fluorescence quencher of CDs and recognizer of H2O2 released from the oxidase catalyzed system. Fluorescence recovery would occur after the decomposition of MnO2 NS induced by H2O2, by which a simple and effective strategy could be developed for fluorescence monitoring multiplex biological events. Xanthine (XA) sensing, xanthine oxidase (XOD) inhibitors screening analysis and chiral recognition of glucose enantiomers were performed on PCD/NS to investigate the multifunctional application of the paper-based device. By means of PCD/NS, XA could be determined in the range of 0.1–40 µmol/L with a low detection of limit of 0.06 µmol/L. The IC50 value of allopurinol, the model inhibitor of XOD, was sensitively detected to be 7.4 µmol/L. Glucose enantiomers were also recognized in terms of the specific fluorescence response to d-glucose. This work firstly presented a paper-based device capable of biomarkers detection, inhibitors screening and chiral recognition, which enlightened a promising strategy for the construction of multifunctional devices and hold the great potential application in clinical diagnosis and drug discovery.
The development of a single analytical platform with different functions is highly desirable but remains a challenge at present. Here, a paper-based device based on fluorescent carbon dots (CDs) functionalized paper/MnO2 nanosheets (MnO2 NS) hybrid devices (PCD/NS) was proposed for single-device multi-function applications. MnO2 NS functioned as a fluorescence quencher of CDs and recognizer of H2O2 released from the oxidase catalyzed system. Fluorescence recovery would occur after the decomposition of MnO2 NS induced by H2O2, by which a simple and effective strategy could be developed for fluorescence monitoring multiplex biological events. Xanthine (XA) sensing, xanthine oxidase (XOD) inhibitors screening analysis and chiral recognition of glucose enantiomers were performed on PCD/NS to investigate the multifunctional application of the paper-based device. By means of PCD/NS, XA could be determined in the range of 0.1–40 µmol/L with a low detection of limit of 0.06 µmol/L. The IC50 value of allopurinol, the model inhibitor of XOD, was sensitively detected to be 7.4 µmol/L. Glucose enantiomers were also recognized in terms of the specific fluorescence response to d-glucose. This work firstly presented a paper-based device capable of biomarkers detection, inhibitors screening and chiral recognition, which enlightened a promising strategy for the construction of multifunctional devices and hold the great potential application in clinical diagnosis and drug discovery.
2022, 33(9): 4411-4414
doi: 10.1016/j.cclet.2021.12.029
Abstract:
In this study, an ambient mass spectrometry (AMS) based method was developed for rapid detection of organophosphorus pesticides in strawberry. This method combines an electric arc and a microsyringe tip to realize tip-assisted ambient electric arc ionization (TAAEAI). A high-voltage electric arc can be applied to the microsyringe tip to generate an electric field, which results in corona discharge at the microsyringe tip. The juiced strawberry sample loaded on the tip could be directly ionized with TAAEAI and then analyzed by a mass spectrometer. TAAEAI-MS was successfully applied to analyze 6 organophosphorus pesticides in three strawberry samples. Malathion and profenofos were detected from the investigated strawberry samples. This method could quantitatively determine the contents of organophosphorus pesticides in strawberry with high reproducibility, high precision, and high sensitivity. Sample matrices did not interfere with the pesticide analysis. The recoveries of organophosphorus pesticides spiked in strawberry samples varied between 82.6% and 116% with relative standard deviations (RSDs) less than 9.2%. The limits of detection (LODs) varied between 0.0124 µg/g and 0.0245 µg/g, while the limits of quantification (LOQs) varied between 0.0413 µg/g and 0.0817 µg/g. The coefficients of determination (R2) of the method were determined to be > 0.995. The method established here may have potential application in the detection of organophosphorus pesticides in vegetables and fruits.
In this study, an ambient mass spectrometry (AMS) based method was developed for rapid detection of organophosphorus pesticides in strawberry. This method combines an electric arc and a microsyringe tip to realize tip-assisted ambient electric arc ionization (TAAEAI). A high-voltage electric arc can be applied to the microsyringe tip to generate an electric field, which results in corona discharge at the microsyringe tip. The juiced strawberry sample loaded on the tip could be directly ionized with TAAEAI and then analyzed by a mass spectrometer. TAAEAI-MS was successfully applied to analyze 6 organophosphorus pesticides in three strawberry samples. Malathion and profenofos were detected from the investigated strawberry samples. This method could quantitatively determine the contents of organophosphorus pesticides in strawberry with high reproducibility, high precision, and high sensitivity. Sample matrices did not interfere with the pesticide analysis. The recoveries of organophosphorus pesticides spiked in strawberry samples varied between 82.6% and 116% with relative standard deviations (RSDs) less than 9.2%. The limits of detection (LODs) varied between 0.0124 µg/g and 0.0245 µg/g, while the limits of quantification (LOQs) varied between 0.0413 µg/g and 0.0817 µg/g. The coefficients of determination (R2) of the method were determined to be > 0.995. The method established here may have potential application in the detection of organophosphorus pesticides in vegetables and fruits.
2022, 33(9): 4415-4420
doi: 10.1016/j.cclet.2021.12.035
Abstract:
Luminescent metal organic cages (MOCs) have attracted great interest as a unique class of sensing substrates. In this work, intrinsically fluorescent Zr-MOCs were successfully used as fluorescent probes for the sensitive and selective detection of phosphate anions in water and real samples. When the ligand and Zr ion clusters form a cage, the intrinsic fluorescence of the ligand was tuned from high to weak emission due to the ligand-to-metal charge transfer (LMCT) effect, and this weakened fluorescence can be restored by the addition of phosphate. The degree of fluorescence enhancement is positively correlated with the added phosphate concentration, and the efficacy of this strategy is demonstrated by a linear phosphate detection range of 5–500 µmol/L and a detection limit of 1.06 µmol/L. We discuss the interaction between phosphate and Zr in scattering spectrum and MS, respectively. In comparison to phosphate adsorption on Zr-metal organic frameworks (MOFs), where phosphate connects different numbers of cages, both blocking the LMCT effect and causing the cages to aggregate. We also found that the phosphate displaces the ligand from the cage when the phosphate concentration is further expanded, resulting in the formation of new derivatives. This derivative was shown to be useful as a Lewis acid catalyst and as a rare earth ion adsorbent.
Luminescent metal organic cages (MOCs) have attracted great interest as a unique class of sensing substrates. In this work, intrinsically fluorescent Zr-MOCs were successfully used as fluorescent probes for the sensitive and selective detection of phosphate anions in water and real samples. When the ligand and Zr ion clusters form a cage, the intrinsic fluorescence of the ligand was tuned from high to weak emission due to the ligand-to-metal charge transfer (LMCT) effect, and this weakened fluorescence can be restored by the addition of phosphate. The degree of fluorescence enhancement is positively correlated with the added phosphate concentration, and the efficacy of this strategy is demonstrated by a linear phosphate detection range of 5–500 µmol/L and a detection limit of 1.06 µmol/L. We discuss the interaction between phosphate and Zr in scattering spectrum and MS, respectively. In comparison to phosphate adsorption on Zr-metal organic frameworks (MOFs), where phosphate connects different numbers of cages, both blocking the LMCT effect and causing the cages to aggregate. We also found that the phosphate displaces the ligand from the cage when the phosphate concentration is further expanded, resulting in the formation of new derivatives. This derivative was shown to be useful as a Lewis acid catalyst and as a rare earth ion adsorbent.
