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2021 Volume 32 Issue 6
2021, 32(6): 1831-1833
doi: 10.1016/j.cclet.2021.01.034
Abstract:
Amino group protective strategy has consequently emerged in multistep organic synthesis. Easy and selective deprotection procedures are crucial to facilitate the chemical transformation. Recently, Zhang's group from Henan Normal University collaborating with Chen's group of Nankai University developed a novel strategy for the regiospecific cleavage of inert aryl C—N bonds in N-aryl amides by hypervalent iodine(V) reagents. These procedures allow removal of sort of aryl groups under mild conditions to give primary amides in high efficiency. It bestows these aryl groups with the characteristics of amino protecting groups that might be the supplement of amino protecting group chemistry.
Amino group protective strategy has consequently emerged in multistep organic synthesis. Easy and selective deprotection procedures are crucial to facilitate the chemical transformation. Recently, Zhang's group from Henan Normal University collaborating with Chen's group of Nankai University developed a novel strategy for the regiospecific cleavage of inert aryl C—N bonds in N-aryl amides by hypervalent iodine(V) reagents. These procedures allow removal of sort of aryl groups under mild conditions to give primary amides in high efficiency. It bestows these aryl groups with the characteristics of amino protecting groups that might be the supplement of amino protecting group chemistry.
2021, 32(6): 1834-1846
doi: 10.1016/j.cclet.2020.11.057
Abstract:
Upconversion (UC) technology makes it possible to harvest infrared (IR) light from the sun and has increasingly been employed in recent years to improve the efficiency of solar cells. The progress in the area concerns both research on fundamental principles and processes of UC and technologies of device fabrication. Significant increase of important solar cell parameters, like short-circuit photocurrent density and open-circuit photovoltage as well as the total photon-to-current efficiency, has been accomplished. We here review the research published during the last few years in the area, in particular we consider the two most cherished techniques, namely the incorporation of upconverting nanophosphors directly into the photoanodes of the solar cells and the introduction of plasmonic metal nanoparticles co-existing with the UC particles. Other ways to achieve strong field enhancement, and the use of the non-linear nature of UC, is to apply microlenses, with or without assisting plasmonic excitation. Further enhanced UC action has been demonstrated by broad band and effective harvesting by organic IR antennas, with subsequent mediation by an intermediate nanoshell of the energy into the upconverting core. Codoping, nanohybrid and layer-by-layer technologies involving upconverting particles as well as the use of upconverting nanoparticles in hole-transport and electrolyte layers, tested in recent works, are also reviewed. While most of these technologies employ upconverting rare earth metals for sequential photon absorption, the main alternative technique, namely triplet-triplet annihilation UC using organic materials, is also reviewed. It is our belief that all these approaches will be further much researched in the near future, with potentially great impact on solar cell technology.
Upconversion (UC) technology makes it possible to harvest infrared (IR) light from the sun and has increasingly been employed in recent years to improve the efficiency of solar cells. The progress in the area concerns both research on fundamental principles and processes of UC and technologies of device fabrication. Significant increase of important solar cell parameters, like short-circuit photocurrent density and open-circuit photovoltage as well as the total photon-to-current efficiency, has been accomplished. We here review the research published during the last few years in the area, in particular we consider the two most cherished techniques, namely the incorporation of upconverting nanophosphors directly into the photoanodes of the solar cells and the introduction of plasmonic metal nanoparticles co-existing with the UC particles. Other ways to achieve strong field enhancement, and the use of the non-linear nature of UC, is to apply microlenses, with or without assisting plasmonic excitation. Further enhanced UC action has been demonstrated by broad band and effective harvesting by organic IR antennas, with subsequent mediation by an intermediate nanoshell of the energy into the upconverting core. Codoping, nanohybrid and layer-by-layer technologies involving upconverting particles as well as the use of upconverting nanoparticles in hole-transport and electrolyte layers, tested in recent works, are also reviewed. While most of these technologies employ upconverting rare earth metals for sequential photon absorption, the main alternative technique, namely triplet-triplet annihilation UC using organic materials, is also reviewed. It is our belief that all these approaches will be further much researched in the near future, with potentially great impact on solar cell technology.
2021, 32(6): 1847-1856
doi: 10.1016/j.cclet.2021.02.009
Abstract:
Hydrogen-atom-transfer (HAT) is an efficient way for direct C—H functionalization of inert C—H bonds, therefore it has attracted great interests in recent years. So far, various HAT catalysts have been developed. Among them, quinuclidine and its derivatives show different characters toward other HAT catalysts as they tend to abstract electron-rich and hydridic hydrogens in the presence of weak and neutral C—H bonds. These features enable direct C—H functionalization of compounds with various groups which are unable or difficult by other methods. This review summarizes recent advance of photoinduced reactions with quinuclidine and its derivatives as HAT catalysts and exhibits powerful synthetic potential by using quinuclidine and its derivatives as HAT catalysts.
Hydrogen-atom-transfer (HAT) is an efficient way for direct C—H functionalization of inert C—H bonds, therefore it has attracted great interests in recent years. So far, various HAT catalysts have been developed. Among them, quinuclidine and its derivatives show different characters toward other HAT catalysts as they tend to abstract electron-rich and hydridic hydrogens in the presence of weak and neutral C—H bonds. These features enable direct C—H functionalization of compounds with various groups which are unable or difficult by other methods. This review summarizes recent advance of photoinduced reactions with quinuclidine and its derivatives as HAT catalysts and exhibits powerful synthetic potential by using quinuclidine and its derivatives as HAT catalysts.
2021, 32(6): 1857-1868
doi: 10.1016/j.cclet.2021.01.014
Abstract:
Alzheimer's disease (AD) is a progressive and fatal neurodegenerative condition and the most prevalent cause of dementia. This disease is characterized by progressive cognitive impairment. The prevalence of AD is currently affecting more than 35 million people and is rising worldwide. No efficient therapy is currently available due to low drug potency and a number of various obstacles to delivery. Recent nanotechnological advancements have the potential to offer promising therapeutic options. Progress on nanomaterials as well as their applications in biomedicine is receiving increasing attention, especially the advantages of nanomaterial-based drug delivery systems. The aim of this review is to comprehensively summarize the latest developments in nanomaterial-based strategies for AD treatment, including nanoparticles, liposomes and other options for the delivery of therapeutic compounds and scaffolds for cell delivery strategies. Future research directions are also proposed. We hope this review can provide important information to guide the future development of nanomaterials in AD treatment.
Alzheimer's disease (AD) is a progressive and fatal neurodegenerative condition and the most prevalent cause of dementia. This disease is characterized by progressive cognitive impairment. The prevalence of AD is currently affecting more than 35 million people and is rising worldwide. No efficient therapy is currently available due to low drug potency and a number of various obstacles to delivery. Recent nanotechnological advancements have the potential to offer promising therapeutic options. Progress on nanomaterials as well as their applications in biomedicine is receiving increasing attention, especially the advantages of nanomaterial-based drug delivery systems. The aim of this review is to comprehensively summarize the latest developments in nanomaterial-based strategies for AD treatment, including nanoparticles, liposomes and other options for the delivery of therapeutic compounds and scaffolds for cell delivery strategies. Future research directions are also proposed. We hope this review can provide important information to guide the future development of nanomaterials in AD treatment.
2021, 32(6): 1869-1878
doi: 10.1016/j.cclet.2020.11.065
Abstract:
Photoelectrochemical (PEC) technology is considered to be a promising approach for solar-driven hydrogen production with zero emissions. Bismuth vanadate (BiVO4) is a kind of photocatalytic material with strong photoactivity in the visible light region and appropriate band gap for PEC water splitting. However, the solar-to-hydrogen efficiency (STH) of BiVO4 is far away from the 10% target needed for practical application due to its poor charge separation ability. Therefore, this review attempts to summarize the strategies for improving the photocurrent density and especially hydrogen production of BiVO4 materials through PEC techniques in the last three years, such as doping nonmetal and metal elements, depositing noble metals, constructing heterojunctions, coupling with carbon and metal-organic framework (MOF) materials to further enhance the PEC performance of BiVO4 photoanode. This review aims to serve as a general guideline to fabricate highly efficient BiVO4-based materials for PEC water splitting.
Photoelectrochemical (PEC) technology is considered to be a promising approach for solar-driven hydrogen production with zero emissions. Bismuth vanadate (BiVO4) is a kind of photocatalytic material with strong photoactivity in the visible light region and appropriate band gap for PEC water splitting. However, the solar-to-hydrogen efficiency (STH) of BiVO4 is far away from the 10% target needed for practical application due to its poor charge separation ability. Therefore, this review attempts to summarize the strategies for improving the photocurrent density and especially hydrogen production of BiVO4 materials through PEC techniques in the last three years, such as doping nonmetal and metal elements, depositing noble metals, constructing heterojunctions, coupling with carbon and metal-organic framework (MOF) materials to further enhance the PEC performance of BiVO4 photoanode. This review aims to serve as a general guideline to fabricate highly efficient BiVO4-based materials for PEC water splitting.
2021, 32(6): 1879-1887
doi: 10.1016/j.cclet.2020.12.060
Abstract:
To better understand the spatial distribution of brain functions, we need to monitor and analyze neuronal activities. Electrophysiological technique has provided an important method for the exploration of some neural circuits. However, this method cannot simultaneously detect the activities of nerve cell groups. Therefore, methods that can monitor the spatial distribution of neuronal population activity are demanded to explore brain functions. Voltage-sensitive dyes (VSDs) shift their absorption or emission optical signals in response to different membrane potentials, allowing assessing the global electrical state of neurons. Optical recording technique coupled with VSDs is a promising method to monitor the brain functions by detecting optical signal changes. This review focuses on the fast and slow responses of VSDs to membrane potential changes and optical recordings utilized in the central nervous system. In this review, we attempt to show how VSDs and optical recordings can be used to obtain brain functional monitoring at high spatial and temporal resolution. Understanding of brain functions will not only greatly improve the cognition of information transmission of complex neural network, but also provide new methods of treating brain diseases such as Parkinson's and Alzheimer's diseases.
To better understand the spatial distribution of brain functions, we need to monitor and analyze neuronal activities. Electrophysiological technique has provided an important method for the exploration of some neural circuits. However, this method cannot simultaneously detect the activities of nerve cell groups. Therefore, methods that can monitor the spatial distribution of neuronal population activity are demanded to explore brain functions. Voltage-sensitive dyes (VSDs) shift their absorption or emission optical signals in response to different membrane potentials, allowing assessing the global electrical state of neurons. Optical recording technique coupled with VSDs is a promising method to monitor the brain functions by detecting optical signal changes. This review focuses on the fast and slow responses of VSDs to membrane potential changes and optical recordings utilized in the central nervous system. In this review, we attempt to show how VSDs and optical recordings can be used to obtain brain functional monitoring at high spatial and temporal resolution. Understanding of brain functions will not only greatly improve the cognition of information transmission of complex neural network, but also provide new methods of treating brain diseases such as Parkinson's and Alzheimer's diseases.
2021, 32(6): 1888-1892
doi: 10.1016/j.cclet.2021.01.036
Abstract:
Vaccine adjuvants have been widely used to enhance the immunogenicity of the antigens and elicit long-lasting immune response. However, only few vaccine adjuvants have been approved by the FDA for human use so far. Therefore, there is still an urgent need to develop novel adjuvants for the potential applications in clinical trials. Herein, non-nucleotide small molecule STING agonist diABZI was employed to construct glycopeptide antigen based vaccines for the first time. Immunological evaluation indicated diABZI not only enhanced the production of antibodies and T cell immune responses, but also inhibited tumor growth in tumor-bearing mice in glycopeptide-based subunit vaccines. These results indicated that di-ABZI demonstrates a high potential as adjuvant for the development of cancer vaccines.
Vaccine adjuvants have been widely used to enhance the immunogenicity of the antigens and elicit long-lasting immune response. However, only few vaccine adjuvants have been approved by the FDA for human use so far. Therefore, there is still an urgent need to develop novel adjuvants for the potential applications in clinical trials. Herein, non-nucleotide small molecule STING agonist diABZI was employed to construct glycopeptide antigen based vaccines for the first time. Immunological evaluation indicated diABZI not only enhanced the production of antibodies and T cell immune responses, but also inhibited tumor growth in tumor-bearing mice in glycopeptide-based subunit vaccines. These results indicated that di-ABZI demonstrates a high potential as adjuvant for the development of cancer vaccines.
2021, 32(6): 1893-1896
doi: 10.1016/j.cclet.2021.01.027
Abstract:
Amphichoterpenoids A–C (1–3), unprecedented picoline-derived meroterpenoids possessing a pyrano[3, 2-c]pyridinyl-γ-pyranone scaffold, were characterized from the ascidian-derived fungus Amphichorda felina SYSU-MS7908. Their structures were elucidated by spectroscopic methods, X-ray diffraction and electronic circular dichroism (ECD) calculations. A plausible biosynthetic pathway was proposed. The isolated compounds displayed moderate inhibitory activity against acetylcholinesterase with 50% inhibiting concentration (IC50) values of 18.8–53.2 μmol/L.
Amphichoterpenoids A–C (1–3), unprecedented picoline-derived meroterpenoids possessing a pyrano[3, 2-c]pyridinyl-γ-pyranone scaffold, were characterized from the ascidian-derived fungus Amphichorda felina SYSU-MS7908. Their structures were elucidated by spectroscopic methods, X-ray diffraction and electronic circular dichroism (ECD) calculations. A plausible biosynthetic pathway was proposed. The isolated compounds displayed moderate inhibitory activity against acetylcholinesterase with 50% inhibiting concentration (IC50) values of 18.8–53.2 μmol/L.
2021, 32(6): 1897-1901
doi: 10.1016/j.cclet.2021.01.033
Abstract:
A series of spirooxindole-ferrocene hybrids bearing five or four contiguous chiral centers were designed and synthesized via organocatalysis. In vitro protein binding and cellular proliferation assays suggested that compound 5d was the most potent mouse double minute 2 homolog (MDM2) inhibitor. In addition, mechanistic studies indicated that compound 5d suppressed MDM2-mediated p53 degradation, induced apoptosis and promoted oxidative damage. Molecular docking studies have suggested that 5d binds to MDM2 by mimicking the Trp23 and Leu26 residues of p53. This work can provide a basis for the development of novel multifunctional MDM2 inhibitors. The further exploration of more derivatives from this library and additional investigation of organocatalysis application in the development of new molecules may generate new potential lead compounds for cancer-targeted therapy.
A series of spirooxindole-ferrocene hybrids bearing five or four contiguous chiral centers were designed and synthesized via organocatalysis. In vitro protein binding and cellular proliferation assays suggested that compound 5d was the most potent mouse double minute 2 homolog (MDM2) inhibitor. In addition, mechanistic studies indicated that compound 5d suppressed MDM2-mediated p53 degradation, induced apoptosis and promoted oxidative damage. Molecular docking studies have suggested that 5d binds to MDM2 by mimicking the Trp23 and Leu26 residues of p53. This work can provide a basis for the development of novel multifunctional MDM2 inhibitors. The further exploration of more derivatives from this library and additional investigation of organocatalysis application in the development of new molecules may generate new potential lead compounds for cancer-targeted therapy.
2021, 32(6): 1902-1906
doi: 10.1016/j.cclet.2021.01.032
Abstract:
An enzyme-responsive polysaccharide supramolecular targeted nanoassembly was successfully constructed by the host-guest complexation of positively charged mono-(6-(tetraethylenepentamine)-6-deoxy)-β-cyclodextrin (TEPA-CD) with adamantane-grafted hyaluronic acid (HA-ADA). Possessing a series of positively charged polyamine chains, the obtained polysaccharide nanoassembly could serve as a biocompatible plasmid DNA (pDNA) container. More interestingly, the pDNA could be released from the nanoassembly through the enzymatic degradation of HA skeleton, which realized the controlled pDNA binding and release. Besides, the polysaccharide nanoassembly exhibited lower cytotoxicity than the commercial transfection reagents 25kDa bPEI (PEI25k), accompanied by similar gene delivery effect. We believe that this work might present a convenient method for targeted, controlled gene delivery.
An enzyme-responsive polysaccharide supramolecular targeted nanoassembly was successfully constructed by the host-guest complexation of positively charged mono-(6-(tetraethylenepentamine)-6-deoxy)-β-cyclodextrin (TEPA-CD) with adamantane-grafted hyaluronic acid (HA-ADA). Possessing a series of positively charged polyamine chains, the obtained polysaccharide nanoassembly could serve as a biocompatible plasmid DNA (pDNA) container. More interestingly, the pDNA could be released from the nanoassembly through the enzymatic degradation of HA skeleton, which realized the controlled pDNA binding and release. Besides, the polysaccharide nanoassembly exhibited lower cytotoxicity than the commercial transfection reagents 25kDa bPEI (PEI25k), accompanied by similar gene delivery effect. We believe that this work might present a convenient method for targeted, controlled gene delivery.
2021, 32(6): 1907-1910
doi: 10.1016/j.cclet.2021.01.021
Abstract:
An efficient and eco-friendly protocol for synthesizing difluoromethylated oxindoles through a visible-light induced one-pot tandem reaction of N-arylacrylamides, difluoroacetic acid and PhI(OAc)2 was developed. This reaction proceeded in the absence of any additive, base, metal-catalyst and external photosensitizer, using cheap and easily available CHF2CO2H as the difluoromethylation reagent and bulk biomass-derived 2-MeTHF as the sole solvent. 26 Examples of N-arylacrylamide substrates were investigated, and all of them successfully underwent difluoromethylation to deliver the target products in good to excellent yields.
An efficient and eco-friendly protocol for synthesizing difluoromethylated oxindoles through a visible-light induced one-pot tandem reaction of N-arylacrylamides, difluoroacetic acid and PhI(OAc)2 was developed. This reaction proceeded in the absence of any additive, base, metal-catalyst and external photosensitizer, using cheap and easily available CHF2CO2H as the difluoromethylation reagent and bulk biomass-derived 2-MeTHF as the sole solvent. 26 Examples of N-arylacrylamide substrates were investigated, and all of them successfully underwent difluoromethylation to deliver the target products in good to excellent yields.
2021, 32(6): 1911-1914
doi: 10.1016/j.cclet.2021.01.052
Abstract:
The reaction of a metallo-organic ligand (LA) in which two "V"-shaped bisterpyridines attaching to meta-position of "X"-shaped tetraterpyridine via < tpy-Ru2+-tpy > connectivity and Zn2+ ions gave rise to 3D supramolecular architectures: octagram (Zn8LA4). However, a position varied ligand (LB) in which two "V"-shaped bisterpyridines locating at the ortho-position of "X"-shaped tetraterpyridine afforded a different 3D hexagram (Zn6LB3). Full characterizations included NMR (1H, 13C, 2D COSY, NOESY and DOSY), ESI-MS, TWIM-MS, TEM and AFM. The resulted structures were directly determined by the position of two "V"-shaped bisterpyridines attaching to "X"-shaped tetraterpyridine.
The reaction of a metallo-organic ligand (LA) in which two "V"-shaped bisterpyridines attaching to meta-position of "X"-shaped tetraterpyridine via < tpy-Ru2+-tpy > connectivity and Zn2+ ions gave rise to 3D supramolecular architectures: octagram (Zn8LA4). However, a position varied ligand (LB) in which two "V"-shaped bisterpyridines locating at the ortho-position of "X"-shaped tetraterpyridine afforded a different 3D hexagram (Zn6LB3). Full characterizations included NMR (1H, 13C, 2D COSY, NOESY and DOSY), ESI-MS, TWIM-MS, TEM and AFM. The resulted structures were directly determined by the position of two "V"-shaped bisterpyridines attaching to "X"-shaped tetraterpyridine.
2021, 32(6): 1915-1919
doi: 10.1016/j.cclet.2021.02.001
Abstract:
Novel and efficient Mn(OAc)3·2H2O promoted radical addition-[4+1] cyclization relay of 3-indolymethanols and phosphites was disclosed, which afforded 1, 2-oxaphospholoindole derivatives in moderate to good yields. Based on the experimental and computational studies, a mechanism involving radical addition and intramolecular cyclization cascade was proposed.
Novel and efficient Mn(OAc)3·2H2O promoted radical addition-[4+1] cyclization relay of 3-indolymethanols and phosphites was disclosed, which afforded 1, 2-oxaphospholoindole derivatives in moderate to good yields. Based on the experimental and computational studies, a mechanism involving radical addition and intramolecular cyclization cascade was proposed.
2021, 32(6): 1920-1924
doi: 10.1016/j.cclet.2021.02.041
Abstract:
4-Hydroxyphenylpyruvate dioxygenase (HPPD) is an important target for both drug and pesticide discovery. As a typical Fe(Ⅱ)-dependent dioxygenase, HPPD catalyzes the complicated transformation of 4-hydroxyphenylpyruvic acid (HPPA) to homogentisic acid (HGA). The binding mode of HPPA in the catalytic pocket of HPPD is a focus of research interests. Recently, we reported the crystal structure of Arabidopsis thaliana HPPD (AtHPPD) complexed with HPPA and a cobalt ion, which was supposed to mimic the pre-reactive structure of AtHPPD-HPPA-Fe(Ⅱ). Unexpectedly, the present study shows that the restored AtHPPD-HPPA-Fe(Ⅱ) complex is still nonreactive toward the bound dioxygen. QM/MM and QM calculations reveal that the HPPA resists the electrophilic attacking of the bound dioxygen by the trim of its phenyl ring, and the residue Phe381 plays a key role in orienting the phenyl ring. Kinetic study on the F381A mutant reveals that the HPPD-HPPA complex observed in the crystal structure should be an intermediate of the substrate transportation instead of the pre-reactive complex. More importantly, the binding mode of the HPPA in this complex is shared with several well-known HPPD inhibitors, suggesting that these inhibitors resist the association of dioxygen (and exert their inhibitory roles) in the same way as the HPPA. The present study provides insights into the inhibition mechanism of HPPD inhibitors.
4-Hydroxyphenylpyruvate dioxygenase (HPPD) is an important target for both drug and pesticide discovery. As a typical Fe(Ⅱ)-dependent dioxygenase, HPPD catalyzes the complicated transformation of 4-hydroxyphenylpyruvic acid (HPPA) to homogentisic acid (HGA). The binding mode of HPPA in the catalytic pocket of HPPD is a focus of research interests. Recently, we reported the crystal structure of Arabidopsis thaliana HPPD (AtHPPD) complexed with HPPA and a cobalt ion, which was supposed to mimic the pre-reactive structure of AtHPPD-HPPA-Fe(Ⅱ). Unexpectedly, the present study shows that the restored AtHPPD-HPPA-Fe(Ⅱ) complex is still nonreactive toward the bound dioxygen. QM/MM and QM calculations reveal that the HPPA resists the electrophilic attacking of the bound dioxygen by the trim of its phenyl ring, and the residue Phe381 plays a key role in orienting the phenyl ring. Kinetic study on the F381A mutant reveals that the HPPD-HPPA complex observed in the crystal structure should be an intermediate of the substrate transportation instead of the pre-reactive complex. More importantly, the binding mode of the HPPA in this complex is shared with several well-known HPPD inhibitors, suggesting that these inhibitors resist the association of dioxygen (and exert their inhibitory roles) in the same way as the HPPA. The present study provides insights into the inhibition mechanism of HPPD inhibitors.
2021, 32(6): 1925-1928
doi: 10.1016/j.cclet.2021.02.008
Abstract:
A nitro group is a common fluorescence quencher, but its quenching efficiency can be easily affected by the surrounding environment. To date, there has been no systematic study on the effects of electron-withdrawing groups on the quenching efficiency of nitro groups. Herein, by virtue of experimental validation and theoretical calculations, we found that strong electron-withdrawing groups, such as pyridinium and dicyanovinyl groups, are detrimental to the quenching effect of nitro groups. Decreasing the electron-withdrawing ability could restore the nitro group's quenching effect.
A nitro group is a common fluorescence quencher, but its quenching efficiency can be easily affected by the surrounding environment. To date, there has been no systematic study on the effects of electron-withdrawing groups on the quenching efficiency of nitro groups. Herein, by virtue of experimental validation and theoretical calculations, we found that strong electron-withdrawing groups, such as pyridinium and dicyanovinyl groups, are detrimental to the quenching effect of nitro groups. Decreasing the electron-withdrawing ability could restore the nitro group's quenching effect.
2021, 32(6): 1929-1936
doi: 10.1016/j.cclet.2020.12.009
Abstract:
Cyclin-dependent kinases 4 and 6 inhibitors (CDK4/6i) have been demonstrated to trigger antitumor immunity for tumor regression. However, the therapeutic performance of CDK4/6i-meadiated cancer immunotherapy was impaired by the immunosuppressive tumor microenvironment (ITM) due to overexpression of programmed death ligand 1 (PD-L1) on the surface of cancer cell membrane. To improve the immunotherapeutic performance of CDK4/6i, we herein developed endosomal acid-activatable micelleplex for siRNA delivery and PD-L1 knockdown in the tumor cells in vitro and in vivo. We further demonstrated that the combination of PD-L1 knockdown and CDK4/6 inhibition facilitated intratumoral infiltration of cytotoxic T lymphocytes (CTLs), and elicited protective immune response and efficiently suppressed tumor growth in vivo. This study revealed the importance of molecular design of the micelleplex for highly efficient siRNA delivery, which might provide a novel insight for RNAi-based cancer immunotherapy.
Cyclin-dependent kinases 4 and 6 inhibitors (CDK4/6i) have been demonstrated to trigger antitumor immunity for tumor regression. However, the therapeutic performance of CDK4/6i-meadiated cancer immunotherapy was impaired by the immunosuppressive tumor microenvironment (ITM) due to overexpression of programmed death ligand 1 (PD-L1) on the surface of cancer cell membrane. To improve the immunotherapeutic performance of CDK4/6i, we herein developed endosomal acid-activatable micelleplex for siRNA delivery and PD-L1 knockdown in the tumor cells in vitro and in vivo. We further demonstrated that the combination of PD-L1 knockdown and CDK4/6 inhibition facilitated intratumoral infiltration of cytotoxic T lymphocytes (CTLs), and elicited protective immune response and efficiently suppressed tumor growth in vivo. This study revealed the importance of molecular design of the micelleplex for highly efficient siRNA delivery, which might provide a novel insight for RNAi-based cancer immunotherapy.
2021, 32(6): 1937-1941
doi: 10.1016/j.cclet.2020.12.038
Abstract:
Energy transfer and electron transfer are both fundamental mechanisms enabling numerous functional materials and applications. While most materials systems employ either energy transfer or electron transfer, the combined effect of energy and electron transfer processes in a single donor/acceptor system remains largely unexplored. Herein, we demonstrated the energy transfer followed by electron transfer (ETET) process in a molecular dyad TPE-NBD. Due to energy transfer, the fluorescence of TPE-NBD was greatly enhanced in non-polar solvents. In contrast, polar solvents activated subsequent electron transfer and markedly quenched the emission of TPE-NBD. Consequently, ETET endows TPE-NBD with significant polarity sensitivities. We expect that employing ETET could generate many functional materials with unprecedented properties, i.e., for single laser powered multicolor fluorescence imaging and sensing.
Energy transfer and electron transfer are both fundamental mechanisms enabling numerous functional materials and applications. While most materials systems employ either energy transfer or electron transfer, the combined effect of energy and electron transfer processes in a single donor/acceptor system remains largely unexplored. Herein, we demonstrated the energy transfer followed by electron transfer (ETET) process in a molecular dyad TPE-NBD. Due to energy transfer, the fluorescence of TPE-NBD was greatly enhanced in non-polar solvents. In contrast, polar solvents activated subsequent electron transfer and markedly quenched the emission of TPE-NBD. Consequently, ETET endows TPE-NBD with significant polarity sensitivities. We expect that employing ETET could generate many functional materials with unprecedented properties, i.e., for single laser powered multicolor fluorescence imaging and sensing.
2021, 32(6): 1942-1946
doi: 10.1016/j.cclet.2020.12.061
Abstract:
Numerous nanocarriers have been currently developed for intracellular delivery. The potential cytotoxicity of these very small inorganic nanocarriers has raised great consideration. Thus, it becomes of utmost importance to conduct the intracellular trace of nanocarriers. Among many analytical techniques, surface enhanced Raman scattering (SERS) method is one of the current state-of-the-art techniques for cell visualization and trace. In this work, a novel stellate porous silica based gene delivery system has been designed for SERS trace purpose. A stellate porous silica nanoparticle modified with many small Au nanoparticles is designed to replace common metallic SERS tags. The results show that the designed system not only could deliver siRNA into cells for therapy, but also could realize SERS trace with high sensitivity and non-invasive features. The constructed delivery system has considerable potential to trace the dynamic gene delivery in living cells.
Numerous nanocarriers have been currently developed for intracellular delivery. The potential cytotoxicity of these very small inorganic nanocarriers has raised great consideration. Thus, it becomes of utmost importance to conduct the intracellular trace of nanocarriers. Among many analytical techniques, surface enhanced Raman scattering (SERS) method is one of the current state-of-the-art techniques for cell visualization and trace. In this work, a novel stellate porous silica based gene delivery system has been designed for SERS trace purpose. A stellate porous silica nanoparticle modified with many small Au nanoparticles is designed to replace common metallic SERS tags. The results show that the designed system not only could deliver siRNA into cells for therapy, but also could realize SERS trace with high sensitivity and non-invasive features. The constructed delivery system has considerable potential to trace the dynamic gene delivery in living cells.
2021, 32(6): 1947-1952
doi: 10.1016/j.cclet.2021.01.007
Abstract:
The emergence of fluorescent light-up molecular probe, which can specifically turn on their fluorescent in the presence of stimulation factors, has open up a new opportunity to advance biosensing and bioimaging. In this work, we designed and synthesized a peptide-AIE conjugate probe for cell imaging with controlled in situ assembled nanostructures. The modular designed probe is consisted of a self-assembled peptide-tetraphenylethene (TPE) motif, a fibroblast activation protein alpha (FAP-α) responsive motif, a hydrophilic motif and a targeting motif. The probe exhibits typically turn-on fluorescence property specifically triggered by FAP-α, which is a significant overexpressed membrane protein on pancreatic tumor cells. Interestingly, the peptide modified the TPE dramatically impacts the assembled nanostructure, which can be modulated by peptide sequences. As a result, the peptide FF(Phe-Phe) modification of TPE as the self-assembled motif provides a suitable balance of the probe with light-up property and nanofiber assembled structure in situ. Finally, our probe could effectively detect the FAP-α on tumor cells with high specificity. Meantime, the nanofibers in situ assembled on the surface of CAFs enhanced the probe accumulation and prolonged the retention for cell imaging. We envision that this study may inspire new insights into the design of nanostructure controlled AIE light-up bio-probe.
The emergence of fluorescent light-up molecular probe, which can specifically turn on their fluorescent in the presence of stimulation factors, has open up a new opportunity to advance biosensing and bioimaging. In this work, we designed and synthesized a peptide-AIE conjugate probe for cell imaging with controlled in situ assembled nanostructures. The modular designed probe is consisted of a self-assembled peptide-tetraphenylethene (TPE) motif, a fibroblast activation protein alpha (FAP-α) responsive motif, a hydrophilic motif and a targeting motif. The probe exhibits typically turn-on fluorescence property specifically triggered by FAP-α, which is a significant overexpressed membrane protein on pancreatic tumor cells. Interestingly, the peptide modified the TPE dramatically impacts the assembled nanostructure, which can be modulated by peptide sequences. As a result, the peptide FF(Phe-Phe) modification of TPE as the self-assembled motif provides a suitable balance of the probe with light-up property and nanofiber assembled structure in situ. Finally, our probe could effectively detect the FAP-α on tumor cells with high specificity. Meantime, the nanofibers in situ assembled on the surface of CAFs enhanced the probe accumulation and prolonged the retention for cell imaging. We envision that this study may inspire new insights into the design of nanostructure controlled AIE light-up bio-probe.
2021, 32(6): 1953-1956
doi: 10.1016/j.cclet.2021.01.006
Abstract:
Red emissive carbon dots (CDs) powder was synthesized on a large scale from phloroglucinol and boric acid by a novel solid state reaction with yield up to 75%. This method is safe and convenient, for it needs neither high pressure reactors nor complicated post-treatment procedures. The as-prepared carbon dots powder exhibited strong red fluorescence with excitation-independent behavior. XPS measurement and PL spectra suggest that such red fluorescence arise from boron-doped structures in CDs, which increases along with the boron concentration on CDs surface but decreases when the concentration quenching effect takes place. To overcome the aggregation induced fluorescence quenching of the solid CDs powder, the conventional methods are dispersing CDs into a large amount of inert substrates. But our present work provides a new strategy to realize strong red fluorescence of CDs in solid state. As a result, such carbon dots powder works well for latent fingerprint identification on various material surfaces.
Red emissive carbon dots (CDs) powder was synthesized on a large scale from phloroglucinol and boric acid by a novel solid state reaction with yield up to 75%. This method is safe and convenient, for it needs neither high pressure reactors nor complicated post-treatment procedures. The as-prepared carbon dots powder exhibited strong red fluorescence with excitation-independent behavior. XPS measurement and PL spectra suggest that such red fluorescence arise from boron-doped structures in CDs, which increases along with the boron concentration on CDs surface but decreases when the concentration quenching effect takes place. To overcome the aggregation induced fluorescence quenching of the solid CDs powder, the conventional methods are dispersing CDs into a large amount of inert substrates. But our present work provides a new strategy to realize strong red fluorescence of CDs in solid state. As a result, such carbon dots powder works well for latent fingerprint identification on various material surfaces.
2021, 32(6): 1957-1962
doi: 10.1016/j.cclet.2021.01.016
Abstract:
An improved ssDNA library immobilized systematic evolution of ligands by enrichment (SELEX) was applied to select aptamers against carbaryl. After nine selection rounds, a highly enriched ssDNA pool was obtained. The Apta3 was demonstrated as the optimal aptamer. In order to facilitate the modification of aptamer, the Apta3 was further truncated with the dissociation constant (Kd) of 0.364±0.055 μmol/L and a fluorescent aptasensor was developed. The linear range for carbaryl was from 100 nmol/L to 1500 nmol/L, with the limit of detection was as low as 15.23 nmol/L. Besides, the biosensor was validated for the carbaryl spiked real samples, and the recoveries were between 97.7% and 107.3%.
An improved ssDNA library immobilized systematic evolution of ligands by enrichment (SELEX) was applied to select aptamers against carbaryl. After nine selection rounds, a highly enriched ssDNA pool was obtained. The Apta3 was demonstrated as the optimal aptamer. In order to facilitate the modification of aptamer, the Apta3 was further truncated with the dissociation constant (Kd) of 0.364±0.055 μmol/L and a fluorescent aptasensor was developed. The linear range for carbaryl was from 100 nmol/L to 1500 nmol/L, with the limit of detection was as low as 15.23 nmol/L. Besides, the biosensor was validated for the carbaryl spiked real samples, and the recoveries were between 97.7% and 107.3%.
2021, 32(6): 1963-1966
doi: 10.1016/j.cclet.2021.01.035
Abstract:
We have developed a MUC1 antigen-based antitumor vaccine loaded on alum colloid encapsulated inside β-glucan particles (GP-Al). The constructed vaccine induced strong MUC1 antigen specific IgG antibody titers and enhanced CD8+ T cells cytotoxic effect to kill tumor cells. These results indicated that GP-Al can be served as an efficient delivery system and adjuvant for the development of cancer vaccines especially small molecule antigens based cancer vaccines.
We have developed a MUC1 antigen-based antitumor vaccine loaded on alum colloid encapsulated inside β-glucan particles (GP-Al). The constructed vaccine induced strong MUC1 antigen specific IgG antibody titers and enhanced CD8+ T cells cytotoxic effect to kill tumor cells. These results indicated that GP-Al can be served as an efficient delivery system and adjuvant for the development of cancer vaccines especially small molecule antigens based cancer vaccines.
2021, 32(6): 1967-1971
doi: 10.1016/j.cclet.2021.01.030
Abstract:
The sensitive and rapid detection of blood glucose is very important for monitoring and managing diabetes. Herein, a fluorescent/magnetic bimodal sensing strategy is proposed for glucose detection using a multifunction-responsive nanocomposite (MoS2 QDs-MnO2 NS). MoS2 QDs act as fluorescent probes, and MnO2 nanosheets are used as both quenchers and recognizers in this sensing platform. In the presence of glucose-mediated enzyme product (H2O2), MnO2 nanosheet is etched, thus releasing MoS2 QDs and Mn2+ ions, which causes the significantly enhancement of fluorescent and magnetic signals. Furthermore, MoS2 QDs-MnO2 NS-based fluorescent test paper is constructed for H2O2 sensing with the naked eyes. Under optimal conditions, the dual linear ranges of 20-300 μmol/L and 40-250 μmol/L toward glucose detection are obtained for the fluorescent and magnetic mode, respectively. Furthermore, this bimodal assay exhibits good reproducibility and acceptable accuracy in glucose detection of clinical samples, demonstrating great versatility and flexibility of multifunctional probes in glucose detection.
The sensitive and rapid detection of blood glucose is very important for monitoring and managing diabetes. Herein, a fluorescent/magnetic bimodal sensing strategy is proposed for glucose detection using a multifunction-responsive nanocomposite (MoS2 QDs-MnO2 NS). MoS2 QDs act as fluorescent probes, and MnO2 nanosheets are used as both quenchers and recognizers in this sensing platform. In the presence of glucose-mediated enzyme product (H2O2), MnO2 nanosheet is etched, thus releasing MoS2 QDs and Mn2+ ions, which causes the significantly enhancement of fluorescent and magnetic signals. Furthermore, MoS2 QDs-MnO2 NS-based fluorescent test paper is constructed for H2O2 sensing with the naked eyes. Under optimal conditions, the dual linear ranges of 20-300 μmol/L and 40-250 μmol/L toward glucose detection are obtained for the fluorescent and magnetic mode, respectively. Furthermore, this bimodal assay exhibits good reproducibility and acceptable accuracy in glucose detection of clinical samples, demonstrating great versatility and flexibility of multifunctional probes in glucose detection.
2021, 32(6): 1972-1976
doi: 10.1016/j.cclet.2020.09.015
Abstract:
Methane (CH4) controllable activation is the key process for CH4 upgrading, which is sensitive to the surface oxygen species. The high thermal conductivity and superb thermal stability of the hexagonal boron nitride (h-BN) sheet makes a single transition metal atom doped hexagonal boron nitride monolayer (TM-BN) possible to be a promising material for catalyzing methane partial oxidation. The performances of 24 TM-BNs for CH4 activation are systematically investigated during the CH4 oxidation by means of first-principles computation. The calculation results unravel the periodic variation trends for the stability of TM-BN, the adsorption strength and the kind of O2 species, and the resulting CH4 activation performance on TM-BNs. The formed peroxide O22- of which the O—O bond could be broken and O- anions are found to be reactive oxygen species for CH4 activation under the mild conditions. It is found that the redox potential of TM center, including its valence electron number, coordination environment, and the work function of TM-BN, is the underlying reason for the formation of different oxygen species and the resulting activity for CH4 oxidative dehydrogenation.
Methane (CH4) controllable activation is the key process for CH4 upgrading, which is sensitive to the surface oxygen species. The high thermal conductivity and superb thermal stability of the hexagonal boron nitride (h-BN) sheet makes a single transition metal atom doped hexagonal boron nitride monolayer (TM-BN) possible to be a promising material for catalyzing methane partial oxidation. The performances of 24 TM-BNs for CH4 activation are systematically investigated during the CH4 oxidation by means of first-principles computation. The calculation results unravel the periodic variation trends for the stability of TM-BN, the adsorption strength and the kind of O2 species, and the resulting CH4 activation performance on TM-BNs. The formed peroxide O22- of which the O—O bond could be broken and O- anions are found to be reactive oxygen species for CH4 activation under the mild conditions. It is found that the redox potential of TM center, including its valence electron number, coordination environment, and the work function of TM-BN, is the underlying reason for the formation of different oxygen species and the resulting activity for CH4 oxidative dehydrogenation.
2021, 32(6): 1977-1982
doi: 10.1016/j.cclet.2020.09.056
Abstract:
Photocatalytic water splitting utilizing solar energy is considered as one of the most ideal strategies for solving the energy and environmental issues. Recently, two-dimensional (2D) materials with an intrinsic dipole show great chance to achieve excellent photocatalytic performance. In this work, blue-phase monolayer carbon monochalcogenides (CX, X = S, Se) are constructed and systematically studied as photocatalysts for water splitting by performing first-principles calculations based on density functional theory. After confirming the great dynamical, thermal, and mechanical stability of CX monolayers, we observe that they possess moderate band gaps (2.41 eV for CS and 2.46 eV for CSe) and high carrier mobility (3.23 × 104 cm2 V-1 s-1 for CS and 4.27 × 103 cm2 V-1 s-1 for CSe), comparable to those of many recently reported 2D photocatalysts. Moreover, these two monolayer materials are found to have large intrinsic dipole (0.43 D for CS and 0.51 D for CSe), thus the build-in internal electric field can be selfintroduced, which can effectively drive the separation of photongenerated carriers. More importantly, the well-aligned band edge as well as rather pronounced optical absorption in the visible-light and ultraviolet regions further ensure that our proposed CX monolayers can be used as high efficient photocatalysts for water splitting. Additionally, the effects of external strain on the electronic, optical and photocatalytic properties of CX monolayers are also evaluated. These theoretical predictions will stimulate further work to open up the energy-related applications of CX monolayers.
Photocatalytic water splitting utilizing solar energy is considered as one of the most ideal strategies for solving the energy and environmental issues. Recently, two-dimensional (2D) materials with an intrinsic dipole show great chance to achieve excellent photocatalytic performance. In this work, blue-phase monolayer carbon monochalcogenides (CX, X = S, Se) are constructed and systematically studied as photocatalysts for water splitting by performing first-principles calculations based on density functional theory. After confirming the great dynamical, thermal, and mechanical stability of CX monolayers, we observe that they possess moderate band gaps (2.41 eV for CS and 2.46 eV for CSe) and high carrier mobility (3.23 × 104 cm2 V-1 s-1 for CS and 4.27 × 103 cm2 V-1 s-1 for CSe), comparable to those of many recently reported 2D photocatalysts. Moreover, these two monolayer materials are found to have large intrinsic dipole (0.43 D for CS and 0.51 D for CSe), thus the build-in internal electric field can be selfintroduced, which can effectively drive the separation of photongenerated carriers. More importantly, the well-aligned band edge as well as rather pronounced optical absorption in the visible-light and ultraviolet regions further ensure that our proposed CX monolayers can be used as high efficient photocatalysts for water splitting. Additionally, the effects of external strain on the electronic, optical and photocatalytic properties of CX monolayers are also evaluated. These theoretical predictions will stimulate further work to open up the energy-related applications of CX monolayers.
2021, 32(6): 1983-1987
doi: 10.1016/j.cclet.2020.10.024
Abstract:
Transition-metal oxides are considered to be a promising anode material for lithium-ion batteries (LIBs) due to their high capacities, low cost, and ease of synthesis. Herein, a hybrid nanosheet composed of uniform MoO2 nanoparticles (NPs) homogeneously immobilized on the reduced graphene oxide nanosheets (MoO2 NP@rGO) is first synthesized by a self-templating and subsequent calcination treatment. The unique two-dimensional hybridnanosheets provides several merits. rGO can be used as a favorable support for the loading of electrochemically active MoO2 NPs. Meanwhile, MoO2 NPs can effectively prevent the stacking of the rGO. The effective combination of MoO2 NPs and rGO nanosheets furnish additional electrochemically interfacial active sites for extra lithium ion storage. Noticeably, the as-fabricated hybrid nanosheets deliver a reversible capacity of 641 mAh/g after 350 cycles at a current density of 1000 mA/g with a good rate capability. The greatly enhanced lithium storage properties of MoO2 NP@rGO indicate the importance of elaborate construction of novel hybrid hierarchical structures.
Transition-metal oxides are considered to be a promising anode material for lithium-ion batteries (LIBs) due to their high capacities, low cost, and ease of synthesis. Herein, a hybrid nanosheet composed of uniform MoO2 nanoparticles (NPs) homogeneously immobilized on the reduced graphene oxide nanosheets (MoO2 NP@rGO) is first synthesized by a self-templating and subsequent calcination treatment. The unique two-dimensional hybridnanosheets provides several merits. rGO can be used as a favorable support for the loading of electrochemically active MoO2 NPs. Meanwhile, MoO2 NPs can effectively prevent the stacking of the rGO. The effective combination of MoO2 NPs and rGO nanosheets furnish additional electrochemically interfacial active sites for extra lithium ion storage. Noticeably, the as-fabricated hybrid nanosheets deliver a reversible capacity of 641 mAh/g after 350 cycles at a current density of 1000 mA/g with a good rate capability. The greatly enhanced lithium storage properties of MoO2 NP@rGO indicate the importance of elaborate construction of novel hybrid hierarchical structures.
2021, 32(6): 1988-1992
doi: 10.1016/j.cclet.2020.10.035
Abstract:
Encapsulation and controlled release of volatile molecules such as fragrances in a designed manner is important but challenging for the flavor and fragrance industry. Here, we report the tuning release of volatile molecules by postsynthetic modification of an amine-terminated metal-organic framework (MOF) MIL-101-NH2. By amidation, we obtained three MIL-101 MOFs, the trimethylacetamide-terminated TC-MIL-101, the benzamide-terminated BC-MIL-101, and the oxalic acid monoamide-terminated OC-MIL-101. All the MOFs can efficiently encapsulate volatile molecules. Moreover, we demonstrate that the release profile of volatiles can be widely tuned to sustain the release in several days to months and even over a year using different modified MIL-101 MOFs. We show that the release profiles are correlated with the binding energies between the guest volatiles and pores in MOFs. The pore diffusion and the synergistic transport are the rate-limiting step of the guest molecules from the modified MOFs.
Encapsulation and controlled release of volatile molecules such as fragrances in a designed manner is important but challenging for the flavor and fragrance industry. Here, we report the tuning release of volatile molecules by postsynthetic modification of an amine-terminated metal-organic framework (MOF) MIL-101-NH2. By amidation, we obtained three MIL-101 MOFs, the trimethylacetamide-terminated TC-MIL-101, the benzamide-terminated BC-MIL-101, and the oxalic acid monoamide-terminated OC-MIL-101. All the MOFs can efficiently encapsulate volatile molecules. Moreover, we demonstrate that the release profile of volatiles can be widely tuned to sustain the release in several days to months and even over a year using different modified MIL-101 MOFs. We show that the release profiles are correlated with the binding energies between the guest volatiles and pores in MOFs. The pore diffusion and the synergistic transport are the rate-limiting step of the guest molecules from the modified MOFs.
2021, 32(6): 1993-1997
doi: 10.1016/j.cclet.2020.10.039
Abstract:
Photoelectrochemical (PEC) water splitting is a promising technology to use solar energy. However, current metal oxides photoanode face the problem of sluggish water oxidation kinetic. In this study, we propose that the sluggish water oxidation process will cause slow mass transfer efficiency, which are rarely considered previously, especially at large bias and strong illumination. Mass transfer refers to the migration of reactants (like H2O and OH-) to the photoanode surface, reaction with holes and diffusion of products (like radical and O2) to the bulk of the electrode. If the migration and diffusion are not fast enough, the mass transfer will inhibit the increase of PEC activity. This problem will be more apparent for nanorod arrays (NRAs), where the space among the NRAs is related narrow. Herein, we solve this problem by decorating the surface of the photoanode by NiO clusters with Ni3+ state as water oxidation cocatalysts. This work studies the PEC process from the viewpoint of mass transfer and firstly demonstrates that mass transfer in NRAs structure can be promoted by using Ni-based water oxidation cocatalyst.
Photoelectrochemical (PEC) water splitting is a promising technology to use solar energy. However, current metal oxides photoanode face the problem of sluggish water oxidation kinetic. In this study, we propose that the sluggish water oxidation process will cause slow mass transfer efficiency, which are rarely considered previously, especially at large bias and strong illumination. Mass transfer refers to the migration of reactants (like H2O and OH-) to the photoanode surface, reaction with holes and diffusion of products (like radical and O2) to the bulk of the electrode. If the migration and diffusion are not fast enough, the mass transfer will inhibit the increase of PEC activity. This problem will be more apparent for nanorod arrays (NRAs), where the space among the NRAs is related narrow. Herein, we solve this problem by decorating the surface of the photoanode by NiO clusters with Ni3+ state as water oxidation cocatalysts. This work studies the PEC process from the viewpoint of mass transfer and firstly demonstrates that mass transfer in NRAs structure can be promoted by using Ni-based water oxidation cocatalyst.
2021, 32(6): 1998-2004
doi: 10.1016/j.cclet.2020.10.041
Abstract:
The rapid development of internet and internet of things brings new opportunities for the expansion of intelligent sensors, and acetone as a major disease detection indicator (i.e., diabetes) making it become extremely important clinical indicator. Herein, uniform mesoporous ZnO spheres were successfully synthesized via novel formaldehyde-assisted metal-ligand crosslinking strategy. In order to adjust the pore structure of mesoporous ZnO, various mesoporous ZnO spheres were synthesized by changing weight percentage of Zn(NO3)2·6H2O to tannic acid (TA). Moreover, highly active heterojunction mesoporous ZnO/Co3O4 has been fabricated based on as-prepared ultra-small Co3O4 nanocrystals (ca. 3 nm) and mesoporous ZnO spheres by flexible impregnation technique. Profit from nano-size effect and synergistic effect of p-n heterojunction, mesoporous ZnO/Co3O4 exhibited excellent acetone sensing performance with high selectivity, superior sensitivity and responsiveness. Typically, 5 wt% Co3O4 embedded mesoporous ZnO sphere showed prominent acetone response (ca. 46 for 50 ppm), which was about 11.5 times higher than that in pure ZnO sensing device, and it was also endowed high cyclic stability. The nanocrystals embedded hybrid material is expected to be used as promising efficient material in the field of catalysis and gas sensing.
The rapid development of internet and internet of things brings new opportunities for the expansion of intelligent sensors, and acetone as a major disease detection indicator (i.e., diabetes) making it become extremely important clinical indicator. Herein, uniform mesoporous ZnO spheres were successfully synthesized via novel formaldehyde-assisted metal-ligand crosslinking strategy. In order to adjust the pore structure of mesoporous ZnO, various mesoporous ZnO spheres were synthesized by changing weight percentage of Zn(NO3)2·6H2O to tannic acid (TA). Moreover, highly active heterojunction mesoporous ZnO/Co3O4 has been fabricated based on as-prepared ultra-small Co3O4 nanocrystals (ca. 3 nm) and mesoporous ZnO spheres by flexible impregnation technique. Profit from nano-size effect and synergistic effect of p-n heterojunction, mesoporous ZnO/Co3O4 exhibited excellent acetone sensing performance with high selectivity, superior sensitivity and responsiveness. Typically, 5 wt% Co3O4 embedded mesoporous ZnO sphere showed prominent acetone response (ca. 46 for 50 ppm), which was about 11.5 times higher than that in pure ZnO sensing device, and it was also endowed high cyclic stability. The nanocrystals embedded hybrid material is expected to be used as promising efficient material in the field of catalysis and gas sensing.
The dynamic covalent reaction based on diselenide-containing crown ether irradiated by visible light
2021, 32(6): 2005-2008
doi: 10.1016/j.cclet.2020.11.043
Abstract:
A novel diselenide-containing crown ether (BC7Se2) was fabricated, which can polymerize to form cyclic oligomers through intermolecular dynamic covalent reaction by irradiation of visible light. The size and distribution of oligomers are related to the monomer concentration. The decomposition reaction of oligomers is controlled by topology and solvents. Furthermore, potassium cation can inhibit the polymerization of BC7Se2 and accelerate the decomposition of oligomers.
A novel diselenide-containing crown ether (BC7Se2) was fabricated, which can polymerize to form cyclic oligomers through intermolecular dynamic covalent reaction by irradiation of visible light. The size and distribution of oligomers are related to the monomer concentration. The decomposition reaction of oligomers is controlled by topology and solvents. Furthermore, potassium cation can inhibit the polymerization of BC7Se2 and accelerate the decomposition of oligomers.
2021, 32(6): 2009-2012
doi: 10.1016/j.cclet.2020.12.025
Abstract:
Aqueous electrolytes are safe, economic, and environmentally friendly. However, they have a narrow potential window. On the other hand, organic electrolytes exhibit good thermodynamic stability but are inflammable and moisture sensitive. In this study, we prepared water-PEG-lipid ternary electrolytes (TEs). To combine the advantages of water, polyethylene glycol (PEG) and propylene carbonate (PC). The nonflammable mixed electrolytes exhibited a wide potential window of about 2.8 V due to the beneficial effects of PEG and PC. Using these TEs, a lithium manganate–active carbon ion capacitor could be operated at 2.4 V with an energy density of 32 Wh/kg, based on the total active electrode material (current density of 3.3 mA/cm2). This value was significantly higher than that achieved using an aqueous electrolyte, thereby rationalizing the higher energy density.
Aqueous electrolytes are safe, economic, and environmentally friendly. However, they have a narrow potential window. On the other hand, organic electrolytes exhibit good thermodynamic stability but are inflammable and moisture sensitive. In this study, we prepared water-PEG-lipid ternary electrolytes (TEs). To combine the advantages of water, polyethylene glycol (PEG) and propylene carbonate (PC). The nonflammable mixed electrolytes exhibited a wide potential window of about 2.8 V due to the beneficial effects of PEG and PC. Using these TEs, a lithium manganate–active carbon ion capacitor could be operated at 2.4 V with an energy density of 32 Wh/kg, based on the total active electrode material (current density of 3.3 mA/cm2). This value was significantly higher than that achieved using an aqueous electrolyte, thereby rationalizing the higher energy density.
Self-assembled lamellar nanochannels in polyoxometalate-polymer nanocomposites for proton conduction
2021, 32(6): 2013-2016
doi: 10.1016/j.cclet.2021.01.051
Abstract:
The construction of nanostructured ion-transport channels is highly desirable in the design of advanced electrolyte materials, as it can enhance ion conductivity by offering short ion-transport pathways. In this work, we present a supramolecular strategy to fabricate a nanocomposite electrolyte containing highly ordered lamellar proton-conducting nanochannels, by the electrostatic self-assembly of a polyoxometalate H3PW12O40 (PW) and a comb copolymer poly(4-methlstyrene)-graft-poly(N-vinyl pyrrolidone). PW can effectively regulate the self-assembling order of polymer moieties to form a large-range lamellar structure, meanwhile, introducing protons into the nanoscale lamellar domains to build proton transport channels. Moreover, the rigid PW clusters contribute a remarkable mechanical reinforcement to the nanocomposites. The lamellar nanocomposite exhibits a conductivity of 4.3×10-4 S/cm and a storage modulus of 1.1×107 Pa at room temperature. This study provides a new strategy to construct nanostructured ion-conductive pathways in electrolyte materials.
The construction of nanostructured ion-transport channels is highly desirable in the design of advanced electrolyte materials, as it can enhance ion conductivity by offering short ion-transport pathways. In this work, we present a supramolecular strategy to fabricate a nanocomposite electrolyte containing highly ordered lamellar proton-conducting nanochannels, by the electrostatic self-assembly of a polyoxometalate H3PW12O40 (PW) and a comb copolymer poly(4-methlstyrene)-graft-poly(N-vinyl pyrrolidone). PW can effectively regulate the self-assembling order of polymer moieties to form a large-range lamellar structure, meanwhile, introducing protons into the nanoscale lamellar domains to build proton transport channels. Moreover, the rigid PW clusters contribute a remarkable mechanical reinforcement to the nanocomposites. The lamellar nanocomposite exhibits a conductivity of 4.3×10-4 S/cm and a storage modulus of 1.1×107 Pa at room temperature. This study provides a new strategy to construct nanostructured ion-conductive pathways in electrolyte materials.
2021, 32(6): 2017-2020
doi: 10.1016/j.cclet.2020.11.066
Abstract:
The remarkable development of nanotechnology and nanoscience has greatly promoted the vigorous development of the field of nanomaterials. This study explores a porous cuboid Ni/NiO composite nanomaterial obtained by calcining NiC2O4·2H2O under a N2 environment. The composite affords direct electrochemical activity and good electrocatalytic properties. Compared to uncalcined precursor, the porous Ni/NiO obtained after calcination exhibited higher catalytic activity for glucose oxidation with higher sensitivity. Moreover, because of its regular cube structure the as-synthesized Ni/NiO exhibited improved electrochemical stability. Such porous Ni/NiO nanocubes represent promising glucose catalyst with high sensitivity and selectivity, improved stability and fast amperometric response.
The remarkable development of nanotechnology and nanoscience has greatly promoted the vigorous development of the field of nanomaterials. This study explores a porous cuboid Ni/NiO composite nanomaterial obtained by calcining NiC2O4·2H2O under a N2 environment. The composite affords direct electrochemical activity and good electrocatalytic properties. Compared to uncalcined precursor, the porous Ni/NiO obtained after calcination exhibited higher catalytic activity for glucose oxidation with higher sensitivity. Moreover, because of its regular cube structure the as-synthesized Ni/NiO exhibited improved electrochemical stability. Such porous Ni/NiO nanocubes represent promising glucose catalyst with high sensitivity and selectivity, improved stability and fast amperometric response.
2021, 32(6): 2021-2026
doi: 10.1016/j.cclet.2020.12.003
Abstract:
The flourishing development in flexible electronics has provoked intensive research in flexible strain sensors to realize accurate perception acquisition under different external stimuli. However, building hydrogel-based strain sensors with high stretchability and sensitivity remains a great challenge. Herein, MXene nanosheets were composited into polyacrylamide-sodium alginate matrix to construct mechanical robust and sensitive double networked hydrogel strain sensor. The hydrophilic MXene nanosheets formed strong interactions with the polymer matrix and endowed the hydrogel with excellent tensile properties (3150%), compliant mechanical strength (2.03 kPa−1 in Young's Module) and long-lasting stability and fatigue resistance (1000 dynamic cycles under 1, 600% strain). Due to the highly oriented MXene-based three dimensional conductive networks, the hydrogel sensor achieved extremely high tensile sensitivity (18.15 in gauge factor) and compression sensitivity (0.38 kPa−1 below 3 kPa). MXene hydrogel-based strain sensors also displayed negligible hysteresis in electromechanical performance, typical frequent-independent feature and rapid response time to external stimuli. Moreover, the sensor exhibited accurate response to different scales of human movements, providing potential application in speech recognition, expression recognition and handwriting verification.
The flourishing development in flexible electronics has provoked intensive research in flexible strain sensors to realize accurate perception acquisition under different external stimuli. However, building hydrogel-based strain sensors with high stretchability and sensitivity remains a great challenge. Herein, MXene nanosheets were composited into polyacrylamide-sodium alginate matrix to construct mechanical robust and sensitive double networked hydrogel strain sensor. The hydrophilic MXene nanosheets formed strong interactions with the polymer matrix and endowed the hydrogel with excellent tensile properties (3150%), compliant mechanical strength (2.03 kPa−1 in Young's Module) and long-lasting stability and fatigue resistance (1000 dynamic cycles under 1, 600% strain). Due to the highly oriented MXene-based three dimensional conductive networks, the hydrogel sensor achieved extremely high tensile sensitivity (18.15 in gauge factor) and compression sensitivity (0.38 kPa−1 below 3 kPa). MXene hydrogel-based strain sensors also displayed negligible hysteresis in electromechanical performance, typical frequent-independent feature and rapid response time to external stimuli. Moreover, the sensor exhibited accurate response to different scales of human movements, providing potential application in speech recognition, expression recognition and handwriting verification.
2021, 32(6): 2027-2032
doi: 10.1016/j.cclet.2020.12.011
Abstract:
The high specific capacitance along with good cycling stability are crucial for practical applications of supercapacitors, which always demands high-performance and stable electrode materials. In this work, we report a series of ternary composites of CoO-ZnO with different fractions of reduced graphene oxide (rGO) synthesized by in-situ growth on nickel foam, named as CZG-1, 2 and 3, respectively. This sort of binder-free electrodes presents excellent electrochemical properties as well as large capacitance due to their low electrical resistance and high oxygen vacancies. Particularly, the sample of CZG-2 (CoO-ZnO/rGO 20 mg) in a nanoreticular structure shows the best electrochemical performance with a maximum specific capacitance of 1951.8 F/g (216.9 mAh/g) at a current intensity of 1 A/g. The CZG-2-based hybrid supercapacitor delivers a high energy density up to 45.9 Wh/kg at a high power density of 800 W/kg, and kept the capacitance retention of 90.1% over 5000 charge-discharge cycles.
The high specific capacitance along with good cycling stability are crucial for practical applications of supercapacitors, which always demands high-performance and stable electrode materials. In this work, we report a series of ternary composites of CoO-ZnO with different fractions of reduced graphene oxide (rGO) synthesized by in-situ growth on nickel foam, named as CZG-1, 2 and 3, respectively. This sort of binder-free electrodes presents excellent electrochemical properties as well as large capacitance due to their low electrical resistance and high oxygen vacancies. Particularly, the sample of CZG-2 (CoO-ZnO/rGO 20 mg) in a nanoreticular structure shows the best electrochemical performance with a maximum specific capacitance of 1951.8 F/g (216.9 mAh/g) at a current intensity of 1 A/g. The CZG-2-based hybrid supercapacitor delivers a high energy density up to 45.9 Wh/kg at a high power density of 800 W/kg, and kept the capacitance retention of 90.1% over 5000 charge-discharge cycles.
2021, 32(6): 2033-2037
doi: 10.1016/j.cclet.2020.11.071
Abstract:
The methanol oxidation reaction (MOR) is the limiting half-reaction in direct methanol fuel cell (DMFC). Although Pt is the most active single-metal electrocatalyst for MOR, it is hampered by high cost and CO poisoning. Constructing a Pt or Ru monolayer on a second metal substrate by means of galvanic replacement of underpotentially deposited (UPD) Cu monolayer has been shown as an efficient catalyst design strategy for the electrocatalysis of MOR because of the presumed 100% utilization of atoms and resistance to CO poisoning. Herein, we prepared one-dimensional surface-alloyed electrocatalyst from predominantly (111) faceted Au nanowires with high aspect ratio as the substrate of under-potential deposition. The electrocatalyst comprises a core of the Au nanowire and a shell of catalytically active Pt coated by Ru. Coverage-dependent electro-catalytic activity and stability is demonstrated on the Pt/Ru submonolayers on Au wires for MOR. Among all these catalysts, Au@PtML@RuML exhibits the best electrocatalytic activity and poisoning tolerance to CO. This presents a viable method for the rational catalyst design for achieving high noble-metal utilization efficiency and high catalytic performance.
The methanol oxidation reaction (MOR) is the limiting half-reaction in direct methanol fuel cell (DMFC). Although Pt is the most active single-metal electrocatalyst for MOR, it is hampered by high cost and CO poisoning. Constructing a Pt or Ru monolayer on a second metal substrate by means of galvanic replacement of underpotentially deposited (UPD) Cu monolayer has been shown as an efficient catalyst design strategy for the electrocatalysis of MOR because of the presumed 100% utilization of atoms and resistance to CO poisoning. Herein, we prepared one-dimensional surface-alloyed electrocatalyst from predominantly (111) faceted Au nanowires with high aspect ratio as the substrate of under-potential deposition. The electrocatalyst comprises a core of the Au nanowire and a shell of catalytically active Pt coated by Ru. Coverage-dependent electro-catalytic activity and stability is demonstrated on the Pt/Ru submonolayers on Au wires for MOR. Among all these catalysts, Au@PtML@RuML exhibits the best electrocatalytic activity and poisoning tolerance to CO. This presents a viable method for the rational catalyst design for achieving high noble-metal utilization efficiency and high catalytic performance.
2021, 32(6): 2038-2042
doi: 10.1016/j.cclet.2020.10.002
Abstract:
Surface oxygen vacancy defects and metal deposition on semiconductor photocatalysts play a critical role in photocatalytic reactions. In this work, oxygen-deficient Bi2WO6 microspheres have been prepared by a facile ethylene glycol-assisted solvothermal method. Bi0 nanoparticles were reduced by in situ thermal-treatment on Bi2WO6 microspheres to obtain Bi0@Bi2WO6-x as well as maintaining the oxygen vacancies (OVs) under N2 atmosphere. Afterwards, photocatalytic NO oxidation removal activities of these photocatalysts were investigated under visible light irradiation and Bi0@Bi2WO6-x shows the best NO removal activity than other samples. The photogenerated charge separation and transfer are promoted by Bi0 nanoparticles deposited on the surface of semiconductor catalysts. OVs defects promote the activation of reactants (H2O and O2), thereby enhancing the formation of the active substance. Moreover, both OVs defects and Bi0 metal have the characteristics of extending light absorption and enhancing the efficient utilization of solar energy. Besides, the photocatalytic NO oxidation mechanism of Bi0@Bi2WO6-x was investigated by in situ FTIR spectroscopy for reaction intermediates and final products. This work furnishes insight into the synthesis strategy and the underlying photocatalytic mechanism of the surface-modified Bi0@Bi2WO6-x composite for pollutants removal.
Surface oxygen vacancy defects and metal deposition on semiconductor photocatalysts play a critical role in photocatalytic reactions. In this work, oxygen-deficient Bi2WO6 microspheres have been prepared by a facile ethylene glycol-assisted solvothermal method. Bi0 nanoparticles were reduced by in situ thermal-treatment on Bi2WO6 microspheres to obtain Bi0@Bi2WO6-x as well as maintaining the oxygen vacancies (OVs) under N2 atmosphere. Afterwards, photocatalytic NO oxidation removal activities of these photocatalysts were investigated under visible light irradiation and Bi0@Bi2WO6-x shows the best NO removal activity than other samples. The photogenerated charge separation and transfer are promoted by Bi0 nanoparticles deposited on the surface of semiconductor catalysts. OVs defects promote the activation of reactants (H2O and O2), thereby enhancing the formation of the active substance. Moreover, both OVs defects and Bi0 metal have the characteristics of extending light absorption and enhancing the efficient utilization of solar energy. Besides, the photocatalytic NO oxidation mechanism of Bi0@Bi2WO6-x was investigated by in situ FTIR spectroscopy for reaction intermediates and final products. This work furnishes insight into the synthesis strategy and the underlying photocatalytic mechanism of the surface-modified Bi0@Bi2WO6-x composite for pollutants removal.
2021, 32(6): 2043-2046
doi: 10.1016/j.cclet.2020.11.009
Abstract:
This work reports the investigation of a new triptycene-derived oxacalixarene (TDOC) as the stationary phase for gas chromatography (GC) with high-resolution performance for a wide range of analytes and isomers. The TDOC scaffold is composed of triptycene and 1, 8-naphthyridine moieties, inherently differing from the conventional calixarenes in structures and properties. As a result, the TDOC column exhibited outstanding column efficiency of 5679 plates/m by n-dodecane at 120 ℃. It showed advantageous performance for separations of the mixtures with various analytes and achieved high resolution of diverse isomers (skeletal, positional andcis-/trans-isomers) from apolar to polar nature. Moreover, the TDOC column exhibited high thermal stability up to 310 ℃. To date, the TDOC-based materials have not been reported in chromatography. This work demonstrates the good potential of the triptycene-derived heterocalixarenes as a new class of stationary phases for chromatographic analyses.
This work reports the investigation of a new triptycene-derived oxacalixarene (TDOC) as the stationary phase for gas chromatography (GC) with high-resolution performance for a wide range of analytes and isomers. The TDOC scaffold is composed of triptycene and 1, 8-naphthyridine moieties, inherently differing from the conventional calixarenes in structures and properties. As a result, the TDOC column exhibited outstanding column efficiency of 5679 plates/m by n-dodecane at 120 ℃. It showed advantageous performance for separations of the mixtures with various analytes and achieved high resolution of diverse isomers (skeletal, positional andcis-/trans-isomers) from apolar to polar nature. Moreover, the TDOC column exhibited high thermal stability up to 310 ℃. To date, the TDOC-based materials have not been reported in chromatography. This work demonstrates the good potential of the triptycene-derived heterocalixarenes as a new class of stationary phases for chromatographic analyses.
2021, 32(6): 2047-2051
doi: 10.1016/j.cclet.2020.11.015
Abstract:
A novel photoenzyme-coupled artificial catalytic system is fabricated by immobilizing horseradish peroxidase (HRP) on the Bi2WO6 hollow nanospheres via a facile electrostatic self-assembly process. The obtained Bi2WO6/HRP sample not only improves the visible light harvest ability but also promotes the high-efficiency separation of charge carriers. More importantly, the photogenerated electrons and produced H2O2 on Bi2WO6 directly take part in redox cycle reactions of HRP to induce photoenzyme synergic catalytic effect. In consequence, the degradation activity of Bi2WO6/HRP is significantly improved relative to Bi2WO6 and HRP for removing bisphenol A (BPA) under the visible light irradiation. This work launches a feasible design strategy for exploiting photoenzyme-coupled artificial catalytic system with special structure to degrade organic pollutants in water efficiently.
A novel photoenzyme-coupled artificial catalytic system is fabricated by immobilizing horseradish peroxidase (HRP) on the Bi2WO6 hollow nanospheres via a facile electrostatic self-assembly process. The obtained Bi2WO6/HRP sample not only improves the visible light harvest ability but also promotes the high-efficiency separation of charge carriers. More importantly, the photogenerated electrons and produced H2O2 on Bi2WO6 directly take part in redox cycle reactions of HRP to induce photoenzyme synergic catalytic effect. In consequence, the degradation activity of Bi2WO6/HRP is significantly improved relative to Bi2WO6 and HRP for removing bisphenol A (BPA) under the visible light irradiation. This work launches a feasible design strategy for exploiting photoenzyme-coupled artificial catalytic system with special structure to degrade organic pollutants in water efficiently.
2021, 32(6): 2052-2056
doi: 10.1016/j.cclet.2020.11.016
Abstract:
The rapid recombination of charge carriers in piezoelectric materials has always been the problem that limits their piezoelectric performance for removal of organic pollutants in water. Herein, we construct a piezoelectric BaTiO3/MoS2 (BTO/MS) that follows a type Ⅱ heterojunction charge transfer system to inhibit the recombination of electron-hole (e‒-h+) pairs, which is beneficial to the activation of peroxymonosulfate (PMS) for the removal of antibiotic ornidazole (ORZ) pollutants. The optimal ratio of BTO/MS for ORZ degradation under the piezo/PMS process is 13.9, 3.6, 62.1 and 2.0 times higher than that of the BTO/piezo, MS/piezo, (BTO/MS)/PMS and (BTO/MS)/piezo processes, respectively. The high efficiency charge separation in the piezoelectric heterojunction of BTO/MS promotes the activation of PMS, resulting in the synergy of pizeocatalysis and PMS oxidation during the process of ORZ degradation. This study provides an idea for enhancing piezo-activation of PMS by constructing heterojunctions in piezoelectric materials.
The rapid recombination of charge carriers in piezoelectric materials has always been the problem that limits their piezoelectric performance for removal of organic pollutants in water. Herein, we construct a piezoelectric BaTiO3/MoS2 (BTO/MS) that follows a type Ⅱ heterojunction charge transfer system to inhibit the recombination of electron-hole (e‒-h+) pairs, which is beneficial to the activation of peroxymonosulfate (PMS) for the removal of antibiotic ornidazole (ORZ) pollutants. The optimal ratio of BTO/MS for ORZ degradation under the piezo/PMS process is 13.9, 3.6, 62.1 and 2.0 times higher than that of the BTO/piezo, MS/piezo, (BTO/MS)/PMS and (BTO/MS)/piezo processes, respectively. The high efficiency charge separation in the piezoelectric heterojunction of BTO/MS promotes the activation of PMS, resulting in the synergy of pizeocatalysis and PMS oxidation during the process of ORZ degradation. This study provides an idea for enhancing piezo-activation of PMS by constructing heterojunctions in piezoelectric materials.
2021, 32(6): 2057-2060
doi: 10.1016/j.cclet.2020.11.062
Abstract:
Herein, a facile glycol reduction route is successful employed to synthesize bimetallic PtAg alloys with homogeneous distribution of sizes and elements. Experimental studies reveal that the ultrafine PtAg alloys with well-defined sizes from around 3.3 nm to 5.8 nm are immobilized onto MnO2 microsphere, which remarkably enhances the catalytic performances for CO oxidation. Importantly, quasi in-situ X-ray photoelectron spectroscopy (XPS) result reveals that both Mn and Pt ions on the surface of catalysts would realize alternating reduction-oxidation by CO and O2 molecules, and the oxygen vacancy sites could be replenished and excited by gas-phase O2.
Herein, a facile glycol reduction route is successful employed to synthesize bimetallic PtAg alloys with homogeneous distribution of sizes and elements. Experimental studies reveal that the ultrafine PtAg alloys with well-defined sizes from around 3.3 nm to 5.8 nm are immobilized onto MnO2 microsphere, which remarkably enhances the catalytic performances for CO oxidation. Importantly, quasi in-situ X-ray photoelectron spectroscopy (XPS) result reveals that both Mn and Pt ions on the surface of catalysts would realize alternating reduction-oxidation by CO and O2 molecules, and the oxygen vacancy sites could be replenished and excited by gas-phase O2.
2021, 32(6): 2061-2065
doi: 10.1016/j.cclet.2020.10.001
Abstract:
Two-dimensional covalent organic framework (COF) has distinctive properties that offer potential opportunities for developing advanced electrode materials. In this work, a core-shell material composed of TAPB-DMTP-COF (TAPB, 1, 3, 5-tris(4-aminophenyl)benzene; DMTP, 2, 5-dimethoxyterephaldehyde) core and conducting polymer shell, TAPB-DMTP-COF@PANI, was synthesized solvothermally using a polymerization method. The structural characteristics of the prepared composite were revealed by X-ray diffraction patterns (XRD), fourier transform infrared spectra (FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM). The electrochemical analyses were verified by subsequent monitoring of trace levels of acetaminophen. This resultant composite not only facilitated acetaminophen to interact with absorption sites by π-π stacking effect and hydrogen bonding but also overcame the poor conductivity of COF. Under the optimal conditions, a low limit of detection of 0.032 μmol/L and wide linear range of 0.10-500 μmol/L were obtained. The electrochemical platform was almost unaffected by other interfering substances, and successfully applied for the practical detection of acetaminophen in commercial tablet, human blood serum and urine. The enhanced performance makes this COF based core-shell composite a promising material in electrochemical sensor.
Two-dimensional covalent organic framework (COF) has distinctive properties that offer potential opportunities for developing advanced electrode materials. In this work, a core-shell material composed of TAPB-DMTP-COF (TAPB, 1, 3, 5-tris(4-aminophenyl)benzene; DMTP, 2, 5-dimethoxyterephaldehyde) core and conducting polymer shell, TAPB-DMTP-COF@PANI, was synthesized solvothermally using a polymerization method. The structural characteristics of the prepared composite were revealed by X-ray diffraction patterns (XRD), fourier transform infrared spectra (FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM). The electrochemical analyses were verified by subsequent monitoring of trace levels of acetaminophen. This resultant composite not only facilitated acetaminophen to interact with absorption sites by π-π stacking effect and hydrogen bonding but also overcame the poor conductivity of COF. Under the optimal conditions, a low limit of detection of 0.032 μmol/L and wide linear range of 0.10-500 μmol/L were obtained. The electrochemical platform was almost unaffected by other interfering substances, and successfully applied for the practical detection of acetaminophen in commercial tablet, human blood serum and urine. The enhanced performance makes this COF based core-shell composite a promising material in electrochemical sensor.
2021, 32(6): 2066-2072
doi: 10.1016/j.cclet.2021.02.019
Abstract:
It is well known that zero-valent iron (ZVI) could catalyze the oxidation of various oxidants to realize the rapid oxidation removal of pollutants. However, in this study, we found that the addition of different oxidants could regulate the redox function of ZVI system. In three different co-treatment systems, the effects of different oxidizers (peroxymonosulfate (PMS), persulfate (PDS), hydrogen peroxide (H2O2)) dosages on the ratios of oxidative degradation rate and reductive degradation rate of p-nitrophenol (PNP) were studied. The effect of the H+ released from oxidizers and the generated reactive oxygen species (ROS) in ZVI/PMS, ZVI/PDS, ZVI/H2O2 systems were detailed discussed. Especially, the contribution of generated ROS for reductive degradation of PNP was quantified in the ZVI/H2O2 system. Based on the results of TOC removal, UV–vis absorption spectra, and intermediates concentration curves, it was found that the degradation of PNP changed from reduction to oxidation with the increase of oxidant proportion. When the molar ratio of ZVI to oxidizer equal to 100, PNP was mainly degraded by reduction accompanied by slight oxidation. Combined with the results of SEM-EDS and XPS, it was confirmed that the enhanced degradation of PNP under the addition of oxidant was mainly related to the generated ROS, the additional H+, and the corrosion products of ZVI.
It is well known that zero-valent iron (ZVI) could catalyze the oxidation of various oxidants to realize the rapid oxidation removal of pollutants. However, in this study, we found that the addition of different oxidants could regulate the redox function of ZVI system. In three different co-treatment systems, the effects of different oxidizers (peroxymonosulfate (PMS), persulfate (PDS), hydrogen peroxide (H2O2)) dosages on the ratios of oxidative degradation rate and reductive degradation rate of p-nitrophenol (PNP) were studied. The effect of the H+ released from oxidizers and the generated reactive oxygen species (ROS) in ZVI/PMS, ZVI/PDS, ZVI/H2O2 systems were detailed discussed. Especially, the contribution of generated ROS for reductive degradation of PNP was quantified in the ZVI/H2O2 system. Based on the results of TOC removal, UV–vis absorption spectra, and intermediates concentration curves, it was found that the degradation of PNP changed from reduction to oxidation with the increase of oxidant proportion. When the molar ratio of ZVI to oxidizer equal to 100, PNP was mainly degraded by reduction accompanied by slight oxidation. Combined with the results of SEM-EDS and XPS, it was confirmed that the enhanced degradation of PNP under the addition of oxidant was mainly related to the generated ROS, the additional H+, and the corrosion products of ZVI.
2021, 32(6): 2073-2078
doi: 10.1016/j.cclet.2021.03.042
Abstract:
The electrocatalysis of nitrate reduction reaction (NRR) has been considered to be a promising nitrate removal technology. Developing a highly effective iron-based electrocatalyst is an essential challenge for NRR. Herein, boron-iron nanochains (B-Fe NCs) as efficient NRR catalysts were prepared via a facile low-cost and scalable method. The Fe/B ratio of the B-Fe NCs-x can be elaborately adjusted to optimize the NRR catalytic performance. Due to the electron transfer from boron to metal, the metal-metal bonds are weakened and the electron density near the metal atom centers are rearranged, which are favor of the conversion from NO3- into N2. Moreover, the well-crosslinked chain-like architectures benefit the mass/electron transport to boost the exposure of abundant catalytic active sites. Laboratory experiments demonstrated that the optimized B-Fe NCs catalyst exhibits superior intrinsic electrocatalytic NRR activity of high nitrate conversion (~80%), ultrahigh nitrogen selectivity (~99%) and excellent long-term reactivity in the mixed electrolyte system (0.02 mol/L NaCl and 0.02 mol/L Na2SO4 mixed electrolyte), and the electrocatalytic activity of the material shows poor performance at low chloride ion concentration (Nitrate conversion of ~61% and nitrogen selectivity of ~57% in 0.005 mol/L NaCl and 0.035 mol/L Na2SO4 mixed electrolyte). This study provides a broad application prospect for further exploring the high-efficiency and low-cost iron-based functional nanostructures for electrocatalytic nitrate reduction.
The electrocatalysis of nitrate reduction reaction (NRR) has been considered to be a promising nitrate removal technology. Developing a highly effective iron-based electrocatalyst is an essential challenge for NRR. Herein, boron-iron nanochains (B-Fe NCs) as efficient NRR catalysts were prepared via a facile low-cost and scalable method. The Fe/B ratio of the B-Fe NCs-x can be elaborately adjusted to optimize the NRR catalytic performance. Due to the electron transfer from boron to metal, the metal-metal bonds are weakened and the electron density near the metal atom centers are rearranged, which are favor of the conversion from NO3- into N2. Moreover, the well-crosslinked chain-like architectures benefit the mass/electron transport to boost the exposure of abundant catalytic active sites. Laboratory experiments demonstrated that the optimized B-Fe NCs catalyst exhibits superior intrinsic electrocatalytic NRR activity of high nitrate conversion (~80%), ultrahigh nitrogen selectivity (~99%) and excellent long-term reactivity in the mixed electrolyte system (0.02 mol/L NaCl and 0.02 mol/L Na2SO4 mixed electrolyte), and the electrocatalytic activity of the material shows poor performance at low chloride ion concentration (Nitrate conversion of ~61% and nitrogen selectivity of ~57% in 0.005 mol/L NaCl and 0.035 mol/L Na2SO4 mixed electrolyte). This study provides a broad application prospect for further exploring the high-efficiency and low-cost iron-based functional nanostructures for electrocatalytic nitrate reduction.
2021, 32(6): 2079-2085
doi: 10.1016/j.cclet.2020.11.027
Abstract:
Green and recyclable solid acid catalysts are in urgent demand as a substitute for conventional liquid mineral acids. In this work, a series of novel sulfonic acid-functionalized core-shell Fe3O4@carbon microspheres (Fe3O4@C-SO3H) have been designed and synthesized as an efficient and recyclable heterogeneous acid catalyst. For the synthesis, core-shell Fe3O4@RF (resorcinol-formaldehyde) microspheres with tunable shell thickness were achieved by interfacial polymerization on magnetic Fe3O4 microspheres. After high-temperature carbonization, the microspheres were eventually treated by surface sulfonation, resulting in Fe3O4@C-x-SO3H (x stands for carbonization temperature) microspheres with abundant surface SO3H groups. The obtained microspheres possess uniform core-shell structure, partially-graphitized carbon skeletons, superparamagnetic property, high magnetization saturation value of 10.6 emu/g, and rich SO3H groups. The surface acid amounts can be adjusted in the range of 0.59–1.04 mmol/g via sulfonation treatment of carbon shells with different graphitization degrees. The magnetic Fe3O4@C-x-SO3H microspheres were utilized as a solid acid catalyst for the acetalization reaction between benzaldehyde and ethylene glycol, demonstrating high selectivity (97%) to benzaldehyde ethylene glycol acetal. More importantly, by applying an external magnetic field, the catalysts can be easily separated from the heterogeneous reaction solutions, which later show well preserved catalytic activity even after 9 cycles, revealing good recyclability and high stability.
Green and recyclable solid acid catalysts are in urgent demand as a substitute for conventional liquid mineral acids. In this work, a series of novel sulfonic acid-functionalized core-shell Fe3O4@carbon microspheres (Fe3O4@C-SO3H) have been designed and synthesized as an efficient and recyclable heterogeneous acid catalyst. For the synthesis, core-shell Fe3O4@RF (resorcinol-formaldehyde) microspheres with tunable shell thickness were achieved by interfacial polymerization on magnetic Fe3O4 microspheres. After high-temperature carbonization, the microspheres were eventually treated by surface sulfonation, resulting in Fe3O4@C-x-SO3H (x stands for carbonization temperature) microspheres with abundant surface SO3H groups. The obtained microspheres possess uniform core-shell structure, partially-graphitized carbon skeletons, superparamagnetic property, high magnetization saturation value of 10.6 emu/g, and rich SO3H groups. The surface acid amounts can be adjusted in the range of 0.59–1.04 mmol/g via sulfonation treatment of carbon shells with different graphitization degrees. The magnetic Fe3O4@C-x-SO3H microspheres were utilized as a solid acid catalyst for the acetalization reaction between benzaldehyde and ethylene glycol, demonstrating high selectivity (97%) to benzaldehyde ethylene glycol acetal. More importantly, by applying an external magnetic field, the catalysts can be easily separated from the heterogeneous reaction solutions, which later show well preserved catalytic activity even after 9 cycles, revealing good recyclability and high stability.
2021, 32(6): 2086-2090
doi: 10.1016/j.cclet.2020.11.003
Abstract:
The sluggish kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) have always restricted the development of lithium oxygen batteries (LOBs). Herein, hollow carbon spheres loaded with Pd/Pd4S heterostructure (Pd/Pd4S@HCS) were successfully prepared via the in-situ deposition to improve the electrocatalytic activities for both ORR and OER in LOBs. With the well-dispersed Pd/Pd4S nanoparticles, the hierarchical composite with large specific surface area offers favorable transport channels for ions, electron and oxygen. Especially, the Pd/Pd4S nanoparticles could exhibit excellent electrochemical performance for ORR and OER due to their intrinsic catalytic property and interfacial effect from the heterostructure. Therefore, the LOBs with Pd/Pd4S@HCS as cathode catalyst show improved specific capacities, good rate ability and stable cycling performance.
The sluggish kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) have always restricted the development of lithium oxygen batteries (LOBs). Herein, hollow carbon spheres loaded with Pd/Pd4S heterostructure (Pd/Pd4S@HCS) were successfully prepared via the in-situ deposition to improve the electrocatalytic activities for both ORR and OER in LOBs. With the well-dispersed Pd/Pd4S nanoparticles, the hierarchical composite with large specific surface area offers favorable transport channels for ions, electron and oxygen. Especially, the Pd/Pd4S nanoparticles could exhibit excellent electrochemical performance for ORR and OER due to their intrinsic catalytic property and interfacial effect from the heterostructure. Therefore, the LOBs with Pd/Pd4S@HCS as cathode catalyst show improved specific capacities, good rate ability and stable cycling performance.
2021, 32(6): 2091-2096
doi: 10.1016/j.cclet.2021.03.024
Abstract:
Physical adsorption is a common method to solve the contamination of methylene blue in dyeing wastewater. As a kind of adsorption material, cellulose aerogels with high porosity and surface areas have great potential application in methylene blue removal. However, the week hydrogen bonding between cellulose nanofibers making the cellulose aerogels with the poor mechanical properties and can be easily destroyed during adsorption. Hence, the preparation of cellulose aerogels with high mechanical strength is still a great challenge. Here, we report a robust super-assembly strategy to fabricate cellulose aerogels by combining cellulose nanofibers with PVA and M-K10. The resulting cellulose aerogels not only has a robust chemically cross-linked network, but also has strong H-bonds, which greatly enhance the mechanical properties. The resulting cellulose aerogels possess a low density of 19.32 mg/cm3. Furthermore, the cellulose aerogel shows 93% shape recovery under 60% strain (9.5 kPa under 60% strain) after 100 cycles, showing excellent mechanical property. The adsorption capacity of cellulose aerogel to methylene blue solution of 20 mg/L is 2.28 mg/g and the adsorption kinetics and adsorption isotherms have also been studied. Pseudo-second-order kinetic model and Freundlich isotherm model are more acceptable for indicating the adsorption process of methylene blue on the cellulose aerogel. Thus, this compressible and durable cellulose aerogel is a very prospective material for dyeing wastewater cleanup.
Physical adsorption is a common method to solve the contamination of methylene blue in dyeing wastewater. As a kind of adsorption material, cellulose aerogels with high porosity and surface areas have great potential application in methylene blue removal. However, the week hydrogen bonding between cellulose nanofibers making the cellulose aerogels with the poor mechanical properties and can be easily destroyed during adsorption. Hence, the preparation of cellulose aerogels with high mechanical strength is still a great challenge. Here, we report a robust super-assembly strategy to fabricate cellulose aerogels by combining cellulose nanofibers with PVA and M-K10. The resulting cellulose aerogels not only has a robust chemically cross-linked network, but also has strong H-bonds, which greatly enhance the mechanical properties. The resulting cellulose aerogels possess a low density of 19.32 mg/cm3. Furthermore, the cellulose aerogel shows 93% shape recovery under 60% strain (9.5 kPa under 60% strain) after 100 cycles, showing excellent mechanical property. The adsorption capacity of cellulose aerogel to methylene blue solution of 20 mg/L is 2.28 mg/g and the adsorption kinetics and adsorption isotherms have also been studied. Pseudo-second-order kinetic model and Freundlich isotherm model are more acceptable for indicating the adsorption process of methylene blue on the cellulose aerogel. Thus, this compressible and durable cellulose aerogel is a very prospective material for dyeing wastewater cleanup.
