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2018 Volume 29 Issue 9
2018, 29(9): 1321-1332
doi: 10.1016/j.cclet.2018.03.004
Abstract:
Lanthanide-doped upconversion nanoparticles (UCNPs) offer unique advantages in term of low autofluorescence, high signal-to-noise ratio and deep tissue penetration, and have attracted considerable attention in biomedical applications. DNA, beyond the properties of self-assembly, also exhibits multiple functions such as molecular recognition, drug loading capacity and therapeutic effect. In this regard, the combination of UCNPs and DNA offers a promising and powerful platform for potential applications in biosensing, bioimaging and disease therapy. In this review, we mainly introduce recent progresses of DNA-functionalized upconversion materials, providing an overview of the design and applications in biosensing, bioimaging and therapy. The challenges and future perspectives are also discussed, aiming to promote their applications in material science and biomedicine.
Lanthanide-doped upconversion nanoparticles (UCNPs) offer unique advantages in term of low autofluorescence, high signal-to-noise ratio and deep tissue penetration, and have attracted considerable attention in biomedical applications. DNA, beyond the properties of self-assembly, also exhibits multiple functions such as molecular recognition, drug loading capacity and therapeutic effect. In this regard, the combination of UCNPs and DNA offers a promising and powerful platform for potential applications in biosensing, bioimaging and disease therapy. In this review, we mainly introduce recent progresses of DNA-functionalized upconversion materials, providing an overview of the design and applications in biosensing, bioimaging and therapy. The challenges and future perspectives are also discussed, aiming to promote their applications in material science and biomedicine.
2018, 29(9): 1333-1339
doi: 10.1016/j.cclet.2018.02.008
Abstract:
Infrared multiple photon dissociation (IRMPD) spectroscopic and theoretical studies of protonated homodimers of amino acids generated by electrospray ionization in the gas phase have been reviewed. Results show that proton affinity (PA) may be applied as a probe to predict their structural type:saltbridged or charge-solvated. Proline can be viewed as a reference. For an amino acid with a PAvalue higher than that of proline, the most stable conformation of its protonated homodimer tends to prefer saltbridged conformation; otherwise, charge-solvated conformation is expected to be the most stable. However, side chain effects may cause the inaccuracy in structural determination due to the strong interactions with the charge, which makes the charge-solvated structure more stable even for species with high PA values. Temperature effect on distribution of different isomers is also very important. In lots of cases, the coexistence of multiple isomers is general, which makes the explanation of an overall IRMPD spectrum difficult. So a statistical view on the distribution of optimized isomers is very helpful.
Infrared multiple photon dissociation (IRMPD) spectroscopic and theoretical studies of protonated homodimers of amino acids generated by electrospray ionization in the gas phase have been reviewed. Results show that proton affinity (PA) may be applied as a probe to predict their structural type:saltbridged or charge-solvated. Proline can be viewed as a reference. For an amino acid with a PAvalue higher than that of proline, the most stable conformation of its protonated homodimer tends to prefer saltbridged conformation; otherwise, charge-solvated conformation is expected to be the most stable. However, side chain effects may cause the inaccuracy in structural determination due to the strong interactions with the charge, which makes the charge-solvated structure more stable even for species with high PA values. Temperature effect on distribution of different isomers is also very important. In lots of cases, the coexistence of multiple isomers is general, which makes the explanation of an overall IRMPD spectrum difficult. So a statistical view on the distribution of optimized isomers is very helpful.
2018, 29(9): 1340-1342
doi: 10.1016/j.cclet.2017.12.014
Abstract:
A practical and efficient synthesis of phosphatidylinositol pentamannoside (PIM5) was achieved based on a five-component one-pot sequential glycosylation protocol with exclusive regio-and stereo-selectivity. Two regioselective sequential glycosylations on inositol and p-tolyl thioglycosides as the sole type of building blocks made this protocol to avoid the tedious protective group manipulations. This synthetic strategy provides access to other important glycolipids with similar structures.
A practical and efficient synthesis of phosphatidylinositol pentamannoside (PIM5) was achieved based on a five-component one-pot sequential glycosylation protocol with exclusive regio-and stereo-selectivity. Two regioselective sequential glycosylations on inositol and p-tolyl thioglycosides as the sole type of building blocks made this protocol to avoid the tedious protective group manipulations. This synthetic strategy provides access to other important glycolipids with similar structures.
2018, 29(9): 1343-1346
doi: 10.1016/j.cclet.2018.01.052
Abstract:
Polymer electron acceptors for all-polymer solar cells (all-PSCs) are usually conjugated copolymers, which contain alternating electron-rich units and electron-deficient units. In this manuscript, we report a conjugated homopolymer (P-BNBP) based on an electron-deficient unit of double B← N bridged bipyridine, which can be used as electron acceptor for all-polymer solar cells. P-BNBP shows low-lying LUMO energy level of -3.59 eV, high absorption coefficient of 1.6×105 Lmol-1 cm-1 at 626 nm and moderate electron mobility of 4.37×10-6 cm2 V-1 s-1. All-PSC devices exhibit power conversion efficiencies of 2.44%-3.04%. These results demonstrate that conjugated homopolymers are promising as electron acceptor materials for all-PSCs.
Polymer electron acceptors for all-polymer solar cells (all-PSCs) are usually conjugated copolymers, which contain alternating electron-rich units and electron-deficient units. In this manuscript, we report a conjugated homopolymer (P-BNBP) based on an electron-deficient unit of double B← N bridged bipyridine, which can be used as electron acceptor for all-polymer solar cells. P-BNBP shows low-lying LUMO energy level of -3.59 eV, high absorption coefficient of 1.6×105 Lmol-1 cm-1 at 626 nm and moderate electron mobility of 4.37×10-6 cm2 V-1 s-1. All-PSC devices exhibit power conversion efficiencies of 2.44%-3.04%. These results demonstrate that conjugated homopolymers are promising as electron acceptor materials for all-PSCs.
2018, 29(9): 1347-1349
doi: 10.1016/j.cclet.2017.11.025
Abstract:
Drug efficiency delivery and release to target site play an important role in the treatment of cancer. To achieve these goals, developing drug delivery systems is the key step. The common materials used for drug delivery like liposomes, micelles, dendrimers cannot control the delivery and releasing by spatial and temporal. In this paper, we design a photoresponsive drug delivery system to reduce the side effects of traditional chemotherapy on normal cells and improve therapeutic efficacy in treating cancers. We synthesized two kinds of photo-responsive polymers using two different monomers containing two photoresponsive groups. The two monomers were crosslinked by poly (ethylene glycol) dimethacrylate to form polymers and then encapsulated β-lapachone into the nanoparticles, after UV irradiation, the particle will degrade and release the drug. This method may provide new strategies for the photoresponsive nanomaterials.
Drug efficiency delivery and release to target site play an important role in the treatment of cancer. To achieve these goals, developing drug delivery systems is the key step. The common materials used for drug delivery like liposomes, micelles, dendrimers cannot control the delivery and releasing by spatial and temporal. In this paper, we design a photoresponsive drug delivery system to reduce the side effects of traditional chemotherapy on normal cells and improve therapeutic efficacy in treating cancers. We synthesized two kinds of photo-responsive polymers using two different monomers containing two photoresponsive groups. The two monomers were crosslinked by poly (ethylene glycol) dimethacrylate to form polymers and then encapsulated β-lapachone into the nanoparticles, after UV irradiation, the particle will degrade and release the drug. This method may provide new strategies for the photoresponsive nanomaterials.
2018, 29(9): 1350-1354
doi: 10.1016/j.cclet.2018.03.009
Abstract:
The design and fabrication of semiconductor photocatalysts have attracted much attention. Herein, the effect of pH value and soluble salt additives on crystal structure, morphology and photocatalytic properties of WO3 was investigated in detail. It was found that the phase structure of WO3 changed from monoclinic to hexagonal phase when pH value of the solution increased. The ultraviolet-visible absorption spectra show that the monoclinic and hexagonal WO3 had absorbance from 600 nm to the ultraviolet-visible region. Hexagonal WO3 with nanofiber bundle morphology was successfully synthesized through Na2SO4 and Zn(CH3COO)2·2H2O-assisted hydrothermal method when pH value was 0.8. It exhibits the highest photocatalytic efficiency and better than that of cubic-shaped monoclinic WO3. The shuttle-like hexagonal WO3 prepared at pH 1.4 gives much lower activity. The morphology is a decisive parameter for the photocatalytic properties of WO3.
The design and fabrication of semiconductor photocatalysts have attracted much attention. Herein, the effect of pH value and soluble salt additives on crystal structure, morphology and photocatalytic properties of WO3 was investigated in detail. It was found that the phase structure of WO3 changed from monoclinic to hexagonal phase when pH value of the solution increased. The ultraviolet-visible absorption spectra show that the monoclinic and hexagonal WO3 had absorbance from 600 nm to the ultraviolet-visible region. Hexagonal WO3 with nanofiber bundle morphology was successfully synthesized through Na2SO4 and Zn(CH3COO)2·2H2O-assisted hydrothermal method when pH value was 0.8. It exhibits the highest photocatalytic efficiency and better than that of cubic-shaped monoclinic WO3. The shuttle-like hexagonal WO3 prepared at pH 1.4 gives much lower activity. The morphology is a decisive parameter for the photocatalytic properties of WO3.
2018, 29(9): 1355-1358
doi: 10.1016/j.cclet.2017.10.034
Abstract:
The rhodium-catalyzed formal C(sp3)-H activation/spiroannulation of α-arylidene pyrazolones with alkynes was investigated by means of density functional theory calculations. The calculations indicate that the spiroannulation through the proposed C-C reductive elimination is kinetically unfeasible. Instead, the C-C coupling from the eight-membered rhodacycle was proposed to account for the experimental results. The overall catalytic cycle consists of six steps:(1) the keto-enol isomerization; (2) the O-H deprotonation, (3) the C(sp2)-H bond cleavage; (4) the migratory insertion of alkyne into the Rh-C bond; (5) the C-C coupling and (6) the regeneration of the active catalyst.
The rhodium-catalyzed formal C(sp3)-H activation/spiroannulation of α-arylidene pyrazolones with alkynes was investigated by means of density functional theory calculations. The calculations indicate that the spiroannulation through the proposed C-C reductive elimination is kinetically unfeasible. Instead, the C-C coupling from the eight-membered rhodacycle was proposed to account for the experimental results. The overall catalytic cycle consists of six steps:(1) the keto-enol isomerization; (2) the O-H deprotonation, (3) the C(sp2)-H bond cleavage; (4) the migratory insertion of alkyne into the Rh-C bond; (5) the C-C coupling and (6) the regeneration of the active catalyst.
2018, 29(9): 1409-1412
doi: 10.1016/j.cclet.2017.12.003
Abstract:
Sulfate-centered Preyssler-type polyoxometalate was used as the precursor to react with transition metal cations and organic ligand for constructing inorganic-organic hybrid materials {H[Ni2(H2O)4(Htrz)3]2(KS5W30O110)}·18H2O (trz=1, 2, 4-triazole) (1), which was characterized by single crystal X-ray diffraction analysis, energy-dispersive X-ray (EDX), power X-ray diffraction (PXRD), IR spectra and thermogravimetric (TG) analyses. In 1, the cylindrical vacancy of the inorganic crown-type anion {S5W30O110} captures a K+ ion resulting in the anion {KS5W30O110}9-, which was further connected by dimeric[Ni2(H2O)4(Htrz)3]2 metal-organic units into an one-dimensional (1D) chain-like structure. These 1D chains are further packed to form a three-dimensional (3D) supramolecular structure via Hbonding interactions. Here, the sulfate-centered Preyssler-typepolyoxometalate was firstly used to coordinate with transition metal cations and introduced into the inorganic-organic hybrid materials. Electrocatalytic study indicates that compound 1 exhibits good electrocatalytic activity toward reduction of H2O2 and NO2-.
Sulfate-centered Preyssler-type polyoxometalate was used as the precursor to react with transition metal cations and organic ligand for constructing inorganic-organic hybrid materials {H[Ni2(H2O)4(Htrz)3]2(KS5W30O110)}·18H2O (trz=1, 2, 4-triazole) (1), which was characterized by single crystal X-ray diffraction analysis, energy-dispersive X-ray (EDX), power X-ray diffraction (PXRD), IR spectra and thermogravimetric (TG) analyses. In 1, the cylindrical vacancy of the inorganic crown-type anion {S5W30O110} captures a K+ ion resulting in the anion {KS5W30O110}9-, which was further connected by dimeric[Ni2(H2O)4(Htrz)3]2 metal-organic units into an one-dimensional (1D) chain-like structure. These 1D chains are further packed to form a three-dimensional (3D) supramolecular structure via Hbonding interactions. Here, the sulfate-centered Preyssler-typepolyoxometalate was firstly used to coordinate with transition metal cations and introduced into the inorganic-organic hybrid materials. Electrocatalytic study indicates that compound 1 exhibits good electrocatalytic activity toward reduction of H2O2 and NO2-.
2018, 29(9): 1413-1416
doi: 10.1016/j.cclet.2017.12.017
Abstract:
In the present work, the sulfur doped bismuth-based catalysts were prepared by incipient wetness impregnation method and used for the hydrochlorination of acetylene to vinyl chloride monomer (VCM) in a fixed-bed reactor. The effect of introduction of S was characterized by N2 adsorption-desorption, powder X-ray diffraction, transmission electron microscopy, thermogravimetric analysis, temperature-programmed reduction and X-ray photoelectron spectroscopy. The characterization results indicated that the doping of S resulted in the increase of Brunauer-Emmett-Teller (BET) surface areas and decrease of active species particle size for the Bi-based catalysts, which led to more accessible active sites, and consequently boosted the catalytic hydrochlorination activity. The effect of H2SO4 concentration on the activity of this type catalyst was examined, and the results showed that there is an optimal loading of H2SO4 (S/Bi=0.5 mol/mol), at which the conversion of C2H2 was enhanced to 81% under the reaction condition and coke deposition is a main reason for the deactivation of catalyst.
In the present work, the sulfur doped bismuth-based catalysts were prepared by incipient wetness impregnation method and used for the hydrochlorination of acetylene to vinyl chloride monomer (VCM) in a fixed-bed reactor. The effect of introduction of S was characterized by N2 adsorption-desorption, powder X-ray diffraction, transmission electron microscopy, thermogravimetric analysis, temperature-programmed reduction and X-ray photoelectron spectroscopy. The characterization results indicated that the doping of S resulted in the increase of Brunauer-Emmett-Teller (BET) surface areas and decrease of active species particle size for the Bi-based catalysts, which led to more accessible active sites, and consequently boosted the catalytic hydrochlorination activity. The effect of H2SO4 concentration on the activity of this type catalyst was examined, and the results showed that there is an optimal loading of H2SO4 (S/Bi=0.5 mol/mol), at which the conversion of C2H2 was enhanced to 81% under the reaction condition and coke deposition is a main reason for the deactivation of catalyst.
2018, 29(9): 1417-1420
doi: 10.1016/j.cclet.2017.11.030
Abstract:
In this paper, nanotubes and nanoribbons of sodium titanate structures were synthesized via hydrothermal methods in alkaline solution. CdS decorated titanate nanotubes and nanoribbons were therefore constructed for exploring the performance of hydrogen evolution and synergistic effect of CdS based titanate structures. CdS decorated titanate nanotubes and nanoribbons were characterized by high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), UV-vis, BrunauerEmmett-Teller (BET) and X-ray photoelectron spectroscopy (XPS) measurements. CdS encapsuled in titanate nanotubes (CdS-ETNTs) showed the best capacity of H2 evolution by water splitting and stability than that from the other two structures, i.e., CdS doped titanate nanotubes (CdS-DTNTs) and CdS doped titanate nanoribbons (CdS-DTNRs), which could be explained by the synergistic effect of decorated CdS with sodium titanate structures and confinement effect of CdS nanoparticles encapsuled inside
In this paper, nanotubes and nanoribbons of sodium titanate structures were synthesized via hydrothermal methods in alkaline solution. CdS decorated titanate nanotubes and nanoribbons were therefore constructed for exploring the performance of hydrogen evolution and synergistic effect of CdS based titanate structures. CdS decorated titanate nanotubes and nanoribbons were characterized by high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), UV-vis, BrunauerEmmett-Teller (BET) and X-ray photoelectron spectroscopy (XPS) measurements. CdS encapsuled in titanate nanotubes (CdS-ETNTs) showed the best capacity of H2 evolution by water splitting and stability than that from the other two structures, i.e., CdS doped titanate nanotubes (CdS-DTNTs) and CdS doped titanate nanoribbons (CdS-DTNRs), which could be explained by the synergistic effect of decorated CdS with sodium titanate structures and confinement effect of CdS nanoparticles encapsuled inside
ICG@ZIF-8:One-step encapsulation of indocyanine green in ZIF-8 and use as a therapeutic nanoplatform
2018, 29(9): 1421-1424
doi: 10.1016/j.cclet.2018.02.014
Abstract:
How to fabricate zeolitic imidazole framework-8 (ZIF-8) based therapeutic nanoplatform will be of significance in biomedicine considering its good biocompatibility. Herein, we report a one-step encapsulation of indocyanine green (ICG) in ZIF-8 nanoparticles (NPs). The as-prepared ICG@ZIF-8 NPs possess an absorption band in the near infrared region and have the good photothermal conversion efficiency. The in vivo and in vitro studies show that, after loading chemotherapy agent hydrophobic doxorubicin (DOX), ICG@ZIF-8-DOX NPs exhibit the chem-and photothermal synergistic therapy for tumor. In addition, it is found that the embedded ICG molecules in ICG@ZIF-8 NPs can be disassociated and released into the solution upon the 808 nm laser irradiation, demonstrating that as-prepared ICG@ZIF-8 NPs can also be used as the optical imaging probe to trace the degradability behavior of resulting NPs in future
How to fabricate zeolitic imidazole framework-8 (ZIF-8) based therapeutic nanoplatform will be of significance in biomedicine considering its good biocompatibility. Herein, we report a one-step encapsulation of indocyanine green (ICG) in ZIF-8 nanoparticles (NPs). The as-prepared ICG@ZIF-8 NPs possess an absorption band in the near infrared region and have the good photothermal conversion efficiency. The in vivo and in vitro studies show that, after loading chemotherapy agent hydrophobic doxorubicin (DOX), ICG@ZIF-8-DOX NPs exhibit the chem-and photothermal synergistic therapy for tumor. In addition, it is found that the embedded ICG molecules in ICG@ZIF-8 NPs can be disassociated and released into the solution upon the 808 nm laser irradiation, demonstrating that as-prepared ICG@ZIF-8 NPs can also be used as the optical imaging probe to trace the degradability behavior of resulting NPs in future
2018, 29(9): 1359-1362
doi: 10.1016/j.cclet.2017.12.005
Abstract:
An environmentally friendly and transition metal-free method for the preparation of chiral α-hydroxysilanes was developed. Enantioselective addition of a silicon nucleophile to aromatic aldehydes in water was achieved by using a new hydroxyl-functionalized chiral carbene as catalyst, affording the corresponding products in good yields and moderate enantioselectivities.
An environmentally friendly and transition metal-free method for the preparation of chiral α-hydroxysilanes was developed. Enantioselective addition of a silicon nucleophile to aromatic aldehydes in water was achieved by using a new hydroxyl-functionalized chiral carbene as catalyst, affording the corresponding products in good yields and moderate enantioselectivities.
2018, 29(9): 1363-1366
doi: 10.1016/j.cclet.2017.12.013
Abstract:
In this work, an efficient copper-catalyzed three-component reaction for the synthesis of sulfenylimidazo[1, 2-a]pyridines using elemental sulfur as the sulfenylating agents has been developed. The reaction could proceed smoothly with a high degree of functional group tolerance and provide the desired products in moderate to good yield.
In this work, an efficient copper-catalyzed three-component reaction for the synthesis of sulfenylimidazo[1, 2-a]pyridines using elemental sulfur as the sulfenylating agents has been developed. The reaction could proceed smoothly with a high degree of functional group tolerance and provide the desired products in moderate to good yield.
2018, 29(9): 1367-1371
doi: 10.1016/j.cclet.2017.10.040
Abstract:
In this article, novel silver nanoparticles immobilized on macroporous polybenzoxazine nanocomposites (Ag-poly(BA-ddm)mainx) were prepared as catalysts for catalytic reduction reaction. For this purpose, a main-chain type benzoxazine was cured in dimethyl sulfoxide by thermally activated ring-opening polymerization at 180℃ for 2 days followed by the reduction of silver nitrate in homogeneous polybenzoxazine solution. The porous structure of the resin was confirmed by scanning electron microscope (SEM) analysis and N2 adsorption/desorption studies. Besides, transmission electron microscopy images showed that spherical particles (around 3-10 nm in sized) are dispersed in Ag-poly (BA-ddm)mainx network. The catalytic activity of the as-prepared nanocomposite has been investigated by photometrically monitoring the reduction of methylene blue by an excess of NaBH4. The kinetic data of the reduction reaction was explained by the assumption of a pseudo-first-order reaction with regard to methylene blue (MB). As evidence by Ultraviolet (UV) spectral analysis, the Ag-poly(BA-ddm)mainx catalyst possesses excellent catalytic reduction of MB, and no deactivation or poisoning of the catalyst was observed. The results demonstrate that porous polybenzoxazine supported silver nanoparticles can be applied as reusable catalysts with satisfied catalytic activity.
In this article, novel silver nanoparticles immobilized on macroporous polybenzoxazine nanocomposites (Ag-poly(BA-ddm)mainx) were prepared as catalysts for catalytic reduction reaction. For this purpose, a main-chain type benzoxazine was cured in dimethyl sulfoxide by thermally activated ring-opening polymerization at 180℃ for 2 days followed by the reduction of silver nitrate in homogeneous polybenzoxazine solution. The porous structure of the resin was confirmed by scanning electron microscope (SEM) analysis and N2 adsorption/desorption studies. Besides, transmission electron microscopy images showed that spherical particles (around 3-10 nm in sized) are dispersed in Ag-poly (BA-ddm)mainx network. The catalytic activity of the as-prepared nanocomposite has been investigated by photometrically monitoring the reduction of methylene blue by an excess of NaBH4. The kinetic data of the reduction reaction was explained by the assumption of a pseudo-first-order reaction with regard to methylene blue (MB). As evidence by Ultraviolet (UV) spectral analysis, the Ag-poly(BA-ddm)mainx catalyst possesses excellent catalytic reduction of MB, and no deactivation or poisoning of the catalyst was observed. The results demonstrate that porous polybenzoxazine supported silver nanoparticles can be applied as reusable catalysts with satisfied catalytic activity.
2018, 29(9): 1372-1374
doi: 10.1016/j.cclet.2017.10.029
Abstract:
Three tetraurea-appended porphyrin derivatives were synthesized and applied as anion receptors to complex with various anions, including F-, Cl-, Br-, I-, NO3-, HSO4-, and AcO-. The binding stoichiometries were all measured to be 1:1 and high binding abilities of these receptors toward the anions were demonstrated with the association constants of up to 1.1×108 L/mol. The complexation of the receptors with anions was further unambiguously confirmed by single-crystal X-ray analysis
Three tetraurea-appended porphyrin derivatives were synthesized and applied as anion receptors to complex with various anions, including F-, Cl-, Br-, I-, NO3-, HSO4-, and AcO-. The binding stoichiometries were all measured to be 1:1 and high binding abilities of these receptors toward the anions were demonstrated with the association constants of up to 1.1×108 L/mol. The complexation of the receptors with anions was further unambiguously confirmed by single-crystal X-ray analysis
2018, 29(9): 1375-1378
doi: 10.1016/j.cclet.2017.11.022
Abstract:
Allatostatins (ASTs), a family of insect neuropeptide, can inhibit juvenile hormone (JH) biosynthesis by the corpora allata (CA) in Diploptera punctata, and therefore be regarded as potential leads for the discovery of new insect growth regulators (IGRs). But several shortcomings, such as their sensitivity to peptidases and high cost, impeded their practical application in pest management. In order to discover new IGRs, one ASTanalog B1 possessing non-peptide group was discovered with high ability to inhibit JH biosynthesis in vitro (IC50:0.09 μmol/L) in our previous studies. In the present work, two series of B1 analogs with different substituents on the N-terminus region were designed and synthesized. The result suggested that benzene showed better activity than other heterocycles, and the para-substitution on the benzene was beneficial for activity. Moreover, analogs with logP value over 2.0 exhibited good activity, which indicated the hydrophobicity is important to the bioactivity. Three dimension quantitative structure-activity relationship (3D-QSAR) studies were performed to highlight the structural requirements of ASTanalogs, which demonstrated introduction of bulkier substituents on the N-terminus would increase the activity. Analog II12 (IC50:0.08 njmol/L) exhibited similar inhibitory activity to the lead B1, but its synthetic route was simpler than B1. Therefore, II12could be used as a new lead compound for the discovery eco-friendly IGRs.
Allatostatins (ASTs), a family of insect neuropeptide, can inhibit juvenile hormone (JH) biosynthesis by the corpora allata (CA) in Diploptera punctata, and therefore be regarded as potential leads for the discovery of new insect growth regulators (IGRs). But several shortcomings, such as their sensitivity to peptidases and high cost, impeded their practical application in pest management. In order to discover new IGRs, one ASTanalog B1 possessing non-peptide group was discovered with high ability to inhibit JH biosynthesis in vitro (IC50:0.09 μmol/L) in our previous studies. In the present work, two series of B1 analogs with different substituents on the N-terminus region were designed and synthesized. The result suggested that benzene showed better activity than other heterocycles, and the para-substitution on the benzene was beneficial for activity. Moreover, analogs with logP value over 2.0 exhibited good activity, which indicated the hydrophobicity is important to the bioactivity. Three dimension quantitative structure-activity relationship (3D-QSAR) studies were performed to highlight the structural requirements of ASTanalogs, which demonstrated introduction of bulkier substituents on the N-terminus would increase the activity. Analog II12 (IC50:0.08 njmol/L) exhibited similar inhibitory activity to the lead B1, but its synthetic route was simpler than B1. Therefore, II12could be used as a new lead compound for the discovery eco-friendly IGRs.
2018, 29(9): 1379-1382
doi: 10.1016/j.cclet.2017.11.023
Abstract:
A novel electrochemical method for the rapid detection of organophosphorus pesticide residues was realized on a dual-channel screen-printed electrode (DSPE) that was integrated with a portable smartphone-controlled potentiostat. The two carbon working channels of DSPE were first modified by electrodepositing of Prussian blue. The channels were then modified with acetylcholinesterase (AChE) via Nafion. The inhibition ratio of AChE was detected by comparing the electrical current of acetylthiocholine (ATCh) that was catalyzed by the enzyme electrodes with (channel 1) and without (channel 2) organophosphorus pesticide. Inhibition ratios were related with the negative logarithm of the organophosphorus pesticide (trichlorfon, oxamyl, and isocarbophos) concentrations at optimum experimental conditions (pH 6.9 of electrolyte, 0.2 V working potential, 2.5 njL AChE modification amount, and 15 min inhibition time). The linear equations were I%=32.30lgC + 253.3 (R=0.9750) for isocarbophos, I%=35.99lgC + 270.1 (R=0.9668) for chlorpyrifos, and I%=33.70lgC + 250.5 (R=0.9606) for trichlorfon. The detection limits were calculated as 10-7 g/mL. Given that the inhibition ratios were only related with pesticide concentration and not with pesticide species, the proposed electrodes and electrometer can rapidly detect universal organophosphorus pesticides and assess pesticide pollution.
A novel electrochemical method for the rapid detection of organophosphorus pesticide residues was realized on a dual-channel screen-printed electrode (DSPE) that was integrated with a portable smartphone-controlled potentiostat. The two carbon working channels of DSPE were first modified by electrodepositing of Prussian blue. The channels were then modified with acetylcholinesterase (AChE) via Nafion. The inhibition ratio of AChE was detected by comparing the electrical current of acetylthiocholine (ATCh) that was catalyzed by the enzyme electrodes with (channel 1) and without (channel 2) organophosphorus pesticide. Inhibition ratios were related with the negative logarithm of the organophosphorus pesticide (trichlorfon, oxamyl, and isocarbophos) concentrations at optimum experimental conditions (pH 6.9 of electrolyte, 0.2 V working potential, 2.5 njL AChE modification amount, and 15 min inhibition time). The linear equations were I%=32.30lgC + 253.3 (R=0.9750) for isocarbophos, I%=35.99lgC + 270.1 (R=0.9668) for chlorpyrifos, and I%=33.70lgC + 250.5 (R=0.9606) for trichlorfon. The detection limits were calculated as 10-7 g/mL. Given that the inhibition ratios were only related with pesticide concentration and not with pesticide species, the proposed electrodes and electrometer can rapidly detect universal organophosphorus pesticides and assess pesticide pollution.
2018, 29(9): 1383-1386
doi: 10.1016/j.cclet.2017.10.026
Abstract:
The detection of Staphylococcus aureus (S. aureus) is very important as it is responsible for bacterial infectious diseases and food poisoning. In this paper we explored the application of fluorescently labelled vancomycin to specifically bind and detect S. aureus. In view of the specificity of vancomycin towards bacterial cell surfaces, we utilized Cy5 to label vancomycin (Cy5-Van) for the identification of S. aureus. Our experiments were designed to examine in greater detail the specificity of the reaction between Cy5-Van and S. aureus. Detection parameters such as the derivatization conditions, concentrations of buffer, pH value, response performance of Cy5-Van to bacterial surface, injection time and reversed-polarity time have been investigated and optimized. To develop a simple and quick assay for the detection of S. aureus at low concentrations, we propose to use the Cy5-Van for labeling the S. aureus coupled with an on-line multiple-concentration in microchip electrophoresis. Under the optimized conditions, the detection of S. aureus was achieved within 150 s with limit of detection (S/N=3) of 981 CFU/mL, and 350-fold enhancement was obtained for S. aureus as compared to using the no concentration step. It is selfevident that this approach has great potential in the future for the analysis of S. aureus.
The detection of Staphylococcus aureus (S. aureus) is very important as it is responsible for bacterial infectious diseases and food poisoning. In this paper we explored the application of fluorescently labelled vancomycin to specifically bind and detect S. aureus. In view of the specificity of vancomycin towards bacterial cell surfaces, we utilized Cy5 to label vancomycin (Cy5-Van) for the identification of S. aureus. Our experiments were designed to examine in greater detail the specificity of the reaction between Cy5-Van and S. aureus. Detection parameters such as the derivatization conditions, concentrations of buffer, pH value, response performance of Cy5-Van to bacterial surface, injection time and reversed-polarity time have been investigated and optimized. To develop a simple and quick assay for the detection of S. aureus at low concentrations, we propose to use the Cy5-Van for labeling the S. aureus coupled with an on-line multiple-concentration in microchip electrophoresis. Under the optimized conditions, the detection of S. aureus was achieved within 150 s with limit of detection (S/N=3) of 981 CFU/mL, and 350-fold enhancement was obtained for S. aureus as compared to using the no concentration step. It is selfevident that this approach has great potential in the future for the analysis of S. aureus.
2018, 29(9): 1387-1390
doi: 10.1016/j.cclet.2017.10.033
Abstract:
The immobilization of acetylcholinesterase (AChE) on amino functionalized SBA-15 mesoporous sieves (NH2-SBA-15) was explored for detection of organophosphorus and carbamate pesticides. Several methods have been studied and the "adsorption-crosslinking" is found to be the best one. Firstly, AChE and bovine serum albumin (BSA) were adsorbed in turn on the surface of NH2-SBA-15 by electrostatic adsorption, and then glutaraldehyde was added for cross-linking the amino group of AChE. The NH2-SBA-15 showed around 95% immobilization efficiency and the specific activity of immobilized AChE (AChENH2-SBA-15) reached 130% relative to free AChE under optimal immobilization conditions. It was found AChE-NH2-SBA-15 retained 94.0% and 82.8% of its initial activity after 60 days at 4℃ and 25℃, respectively. It remained 55.0% of its initial activity after 6 times recycling. During the detection of pesticide, the AChE-NH2-SBA-15 showed wider linear range and much lower limit of detection compared with free AChE. The current method showed good recovery (93.8%-109.3%) and low RSD (< 5%) for both standard solution and real vegetable samples of Carbaryl and Trichlorfon. It was believed that AChE-NH2-SBA-15 could be exploited as a fast, sensitive and low-cost biocatalyst towards the detection of pesticides residues which could be stored at room temperature for a long time.
The immobilization of acetylcholinesterase (AChE) on amino functionalized SBA-15 mesoporous sieves (NH2-SBA-15) was explored for detection of organophosphorus and carbamate pesticides. Several methods have been studied and the "adsorption-crosslinking" is found to be the best one. Firstly, AChE and bovine serum albumin (BSA) were adsorbed in turn on the surface of NH2-SBA-15 by electrostatic adsorption, and then glutaraldehyde was added for cross-linking the amino group of AChE. The NH2-SBA-15 showed around 95% immobilization efficiency and the specific activity of immobilized AChE (AChENH2-SBA-15) reached 130% relative to free AChE under optimal immobilization conditions. It was found AChE-NH2-SBA-15 retained 94.0% and 82.8% of its initial activity after 60 days at 4℃ and 25℃, respectively. It remained 55.0% of its initial activity after 6 times recycling. During the detection of pesticide, the AChE-NH2-SBA-15 showed wider linear range and much lower limit of detection compared with free AChE. The current method showed good recovery (93.8%-109.3%) and low RSD (< 5%) for both standard solution and real vegetable samples of Carbaryl and Trichlorfon. It was believed that AChE-NH2-SBA-15 could be exploited as a fast, sensitive and low-cost biocatalyst towards the detection of pesticides residues which could be stored at room temperature for a long time.
2018, 29(9): 1391-1394
doi: 10.1016/j.cclet.2017.11.005
Abstract:
High-throughput measurements of ciprofloxacin, clomipramine and fexofenadine hydrochlorides were performed by employing an automatic 8-channel electrical titrator. Silver nitrate (AgNO3) and sodium tetraphenylborate (NaTPB) were used as titrants. When AgNO3 was used for measuring the drugs in pure form, recoveries were 97.6%-102.0% with RSD values ≤ 1.0%; for measuring them in pharmaceutical formulations, recoveries were 96.6%-99.1% with RSD values ≤ 1.0%. Batch samples of eight could be measured simultaneously and maximally 30 measurements per minute could be completed. When NaTPB was used for measuring the drugs in pure form, the recoveries were 96.8%-102.6% with RSD values ≤ 0.8%; for measuring them in pharmaceutical formulations, the recoveries were 97.5%-102.7% with RSD values ≤ 0.9%. For all analyses, no auxiliary devices or chemicals were needed and there was no requirement for changing or cleaning working electrodes between measurements. The efficiency, accuracy and precision of the proposed method make it an alternative for routine quality control analyses.
High-throughput measurements of ciprofloxacin, clomipramine and fexofenadine hydrochlorides were performed by employing an automatic 8-channel electrical titrator. Silver nitrate (AgNO3) and sodium tetraphenylborate (NaTPB) were used as titrants. When AgNO3 was used for measuring the drugs in pure form, recoveries were 97.6%-102.0% with RSD values ≤ 1.0%; for measuring them in pharmaceutical formulations, recoveries were 96.6%-99.1% with RSD values ≤ 1.0%. Batch samples of eight could be measured simultaneously and maximally 30 measurements per minute could be completed. When NaTPB was used for measuring the drugs in pure form, the recoveries were 96.8%-102.6% with RSD values ≤ 0.8%; for measuring them in pharmaceutical formulations, the recoveries were 97.5%-102.7% with RSD values ≤ 0.9%. For all analyses, no auxiliary devices or chemicals were needed and there was no requirement for changing or cleaning working electrodes between measurements. The efficiency, accuracy and precision of the proposed method make it an alternative for routine quality control analyses.
2018, 29(9): 1395-1398
doi: 10.1016/j.cclet.2017.11.007
Abstract:
As a rare and valuable wood and herbal material, Dalbergia odorifera is often counterfeited by Dalbergia stevensonii in the market. For the confident chemical identification of D. odorifera and D. stevensonii, the ethanol-benzene extractives are characterized by multiple metabolomics tools, including Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), and gas chromatographymass spectrometry (GC/MS). Conventional FTIR spectroscopy, second derivative infrared (SD-IR) spectroscopy and two-dimensional correlation infrared (2D-IR) spectroscopy are combined to interpret the functional groups of the ethanol-benzene extractives. Fingerprint-like characteristics make FTIR a rapid and accurate method to distinguish D. odorifera from D. stevensonii. Chemical differences of the extractives revealed by FTIR methods can be further confirmed by 1H NMR and 13C NMR. Meanwhile, the volatile compounds in the extractives can be identified by GC/MS. The combination of FTIR, NMR and GC/MS makes it possible to obtain the multiple profiles of the ethanol-benzene extractives, which is essential for the confident chemical identification of D. odorifera and D. stevensonii.
As a rare and valuable wood and herbal material, Dalbergia odorifera is often counterfeited by Dalbergia stevensonii in the market. For the confident chemical identification of D. odorifera and D. stevensonii, the ethanol-benzene extractives are characterized by multiple metabolomics tools, including Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), and gas chromatographymass spectrometry (GC/MS). Conventional FTIR spectroscopy, second derivative infrared (SD-IR) spectroscopy and two-dimensional correlation infrared (2D-IR) spectroscopy are combined to interpret the functional groups of the ethanol-benzene extractives. Fingerprint-like characteristics make FTIR a rapid and accurate method to distinguish D. odorifera from D. stevensonii. Chemical differences of the extractives revealed by FTIR methods can be further confirmed by 1H NMR and 13C NMR. Meanwhile, the volatile compounds in the extractives can be identified by GC/MS. The combination of FTIR, NMR and GC/MS makes it possible to obtain the multiple profiles of the ethanol-benzene extractives, which is essential for the confident chemical identification of D. odorifera and D. stevensonii.
2018, 29(9): 1399-1403
doi: 10.1016/j.cclet.2017.10.039
Abstract:
A chiral stationary phase (CSP) was prepared by chemically bonding carboxymethyl-β-cyclodextrin (CM-β-CD) onto 3-aminopropyl silica gel through amidation reaction in water solution and was characterized by Fourier transform infrared spectroscopy (FT-IR), element analysis (EA) and thermal gravimetry analysis (TGA). The chromatographic performance was evaluated with 24 racemates under reversedphase conditions. The effect of salt, organic modifier, mobile phase pH and structures of analytes were discussed. In comparison with native β-CD bonded column, CYCLOBOND I 2000, CM-β-CD CSP exhibited enhanced enantioseparation.
A chiral stationary phase (CSP) was prepared by chemically bonding carboxymethyl-β-cyclodextrin (CM-β-CD) onto 3-aminopropyl silica gel through amidation reaction in water solution and was characterized by Fourier transform infrared spectroscopy (FT-IR), element analysis (EA) and thermal gravimetry analysis (TGA). The chromatographic performance was evaluated with 24 racemates under reversedphase conditions. The effect of salt, organic modifier, mobile phase pH and structures of analytes were discussed. In comparison with native β-CD bonded column, CYCLOBOND I 2000, CM-β-CD CSP exhibited enhanced enantioseparation.
2018, 29(9): 1404-1408
doi: 10.1016/j.cclet.2017.12.027
Abstract:
The crystal structure of silver(Ⅱ) 5, 10, 15, 20-tetra(ethoxycarbonyl)porphyrin (Ag[Ⅱ]TECP) revealed it formed a one-dimensional coordination polymer through weak Ag-O interactions with an unusual sixcoordinated central silver(Ⅱ) atom.
The crystal structure of silver(Ⅱ) 5, 10, 15, 20-tetra(ethoxycarbonyl)porphyrin (Ag[Ⅱ]TECP) revealed it formed a one-dimensional coordination polymer through weak Ag-O interactions with an unusual sixcoordinated central silver(Ⅱ) atom.
