Chloroplast 2-Cys peroxiredoxins （2-Cys Prxs） are efficiently reduced by NADPH Thioredoxin reductase C （NTRC）. To investigate the effect of light/darkness on NTRC function, the content of abundant plastidial enzym...Chloroplast 2-Cys peroxiredoxins （2-Cys Prxs） are efficiently reduced by NADPH Thioredoxin reductase C （NTRC）. To investigate the effect of light/darkness on NTRC function, the content of abundant plastidial enzymes, Rubisco, glutamine synthetase （GS）, and 2-Cys Prxs was analyzed during two consecutive days in Arabidopsis wild-type and ntrc mutant plants. No significant difference of the content of these proteins was observed during the day or the night in wildtype and mutant plants. NTRC deficiency caused a lower content of fully reduced 2-Cys Prxs, which was undetectable in darkness, suggesting that NTRC is the most important pathway for 2-Cys Prx reduction, probably the only one during the night. Arabidopsis contains two plastidial 2-Cys Prxs, A and B, for which T-DNA insertion lines were characterized showing the same phenotype as wild-type plants. Two-dimensional gel analysis of leaf extracts from these mutants allowed the identification of basic and acidic isoforms of 2-Cys Prx A and B. In-vitro assays and mass spectrometry analysis showed that the acidic isoform of both proteins is produced by overoxidation of the peroxidatic Cys residue to sulfinic acid. 2-Cys Prx overoxidation was lower in the NTRC mutant. These results show the important function of NTRC to maintain the redox equilibrium of chloroplast 2-Cys Prxs.展开更多
烯烃类化合物,如乙烯和丙烯,是工业生产的关键原料,它们可以通过选择性氧化转化为环氧乙烷(EO)和环氧丙烷(PO)等高附加值的化学品.目前,烯烃类化合物转化主要通过热化学途径实现,通常需要高温高压条件,并可能导致过度氧化生成CO_(2),因...烯烃类化合物,如乙烯和丙烯,是工业生产的关键原料,它们可以通过选择性氧化转化为环氧乙烷(EO)和环氧丙烷(PO)等高附加值的化学品.目前,烯烃类化合物转化主要通过热化学途径实现,通常需要高温高压条件,并可能导致过度氧化生成CO_(2),因而选择性较低,且对经济和环境效益不友好.与此相对,电催化反应以电能作为驱动力,通过优化催化剂、电解液和反应电位等,有望在相对温和的条件下提高反应的选择性和能量效率,为高选择性烯烃氧化提供一种潜在策略.然而,当前烯烃的电化学选择性氧化的电流密度较低,整体生产成本相对较高,因此,有必要进一步研发高效且稳定的电化学选择性氧化烯烃的体系.本文综述了近期关于烯烃选择性电化学氧化的研究进展,研究主要集中在两个方面:一是烯烃在电极和电解液界面上直接进行电化学氧化的方法;二是通过电化学反应原位生成氧化剂(如Cl2和H_(2)O_(2))后,再对烯烃进行氧化的间接方法.对于烯烃的直接电化学氧化,反应的选择性可以通过调控几何效应和电子效应来优化.具体来说,通过引入如氯离子这样的物种,减少催化剂表面的可用活性位点数量,从而降低烯烃在催化剂表面的双位吸附,进一步降低过度氧化的可能性.此外,通过调整电催化剂的电子结构,改变其表面氧物种的电子性质,直接影响烯烃的加氧步骤,从而实现对反应选择性的精准调控.烯烃的氧化过程受限于其固有的缓慢反应动力学,导致直接电氧化所能实现的电流密度有限.为了提高该过程的速率,可以引入氧化还原介导物种来实现烯烃的选择性氧化.近期研究结果表明,卤素和过氧化氢作为介导物种在烯烃的选择性氧化反应中表现较好.利用先进的串联反应器技术,过氧化氢介导乙烯氧化为乙二醇的电流密度已经可以达到500m A cm^(–2).深入探索了烯烃电化�展开更多
An innovative,ternary nanocomposite composed of overoxidized poly(3,4-ethylenedioxythiophene)(OPEDOT),gold nanoparticles(Au NPs),and electrochemically reduced graphene oxide(ERGO)was prepared on a glassy carbon electr...An innovative,ternary nanocomposite composed of overoxidized poly(3,4-ethylenedioxythiophene)(OPEDOT),gold nanoparticles(Au NPs),and electrochemically reduced graphene oxide(ERGO)was prepared on a glassy carbon electrode(GCE)(OPEDOT-Au NPs-ERGO/GCE)through homogeneous chemical reactions and heterogeneous electrochemical methods.The morphology,composition,and structure of this nanocomposite were characterized by transmission electron microscopy,scanning electron microscopy,X-ray diffraction,and X-ray photoelectron spectroscopy.The electrochemical properties of the OPEDOT-Au NPs-ERGO/GCE were investigated by cyclic voltammetry using potassium ferricyanide and hexaammineruthenium(III)chloride redox probe systems.This modified electrode shows excellent electro-catalytic activity for dopamine(DA)and uric acid(UA)under physiological p H conditions,but inhibits the oxidation of ascorbic acid(AA).Linear voltammetric responses were obtained when DA concentrations of approximately 4.0-100μM and UA concentrations of approximately 20-100μM were used.The detection limits(S/N=3)for DA and UA were 1.0 and 5.0μM,respectively,under physiological conditions and in the presence of 1.0 m M of AA.This developed method was applied to the simultaneous detection of DA and UA in human urine,where satisfactory recoveries from 96.7%to 105.0%were observed.This work demonstrates that the developed OPEDOT-Au NPs-ERGO ternary nanocomposite,with its excellent ion-selectivity and electro-catalytic activity,is a promising candidate for the simultaneous detection of DA and UA in the presence of AA in physiological and pathological studies.展开更多
The four-year-old Michelia chapensis, M. platypetala, M. foveolata, and M. maudiae leaves were selected as experimental materials, and their ethanol extracts (light yellow liquid) were obtained by method of organic so...The four-year-old Michelia chapensis, M. platypetala, M. foveolata, and M. maudiae leaves were selected as experimental materials, and their ethanol extracts (light yellow liquid) were obtained by method of organic solvent extraction. The antioxidant components of extracts were initially identified by physical and chemical detection and UV scan. Moreover, the activities of anti-overoxidation for four samples on soybean oil were determined, and PA(phytic acid)and PG(propyl gallate)were contrasted. Besides, the regression models of first-order kinetics for soybean oil samples containing additives were fitted. Results showed that the extraction rate of M. chapensis was the highest (13.24%).The anti-overoxidation components of four samples were flavonoids. According to results of Pf (Oxidation Protection Factor) and determining values of MDA, we found that the capacity of anti-overoxidation for the extract from M. platypetala was the strongest(Pf value 1.25, MDA 0.456). The regression relationships for equations of first-order kinetics were significant. They were suitable to fit exponential function curves. The experiment provides scientific basis for the research and exploration of four Michelia species.展开更多
In this study, a simple and effective method was proposed to improve the electrocatalytic ability of overoxidized poly(3,4-ethylenedioxythiophene)-overoxidized polypyrrole composite films modified on glassy carbon ele...In this study, a simple and effective method was proposed to improve the electrocatalytic ability of overoxidized poly(3,4-ethylenedioxythiophene)-overoxidized polypyrrole composite films modified on glassy carbon electrode for rutin and luteolin determination. The composite electrode was prepared by cyclic voltammetry copolymerization with LiClO_(4)-water as the supporting electrolyte. The peak current of rutin and luteolin on the composite electrode gradually decreased or even disappeared with the increase in the positive potential limit. After incubation in NaOH–ethanol solution with a volume ratio of 1:1, the composite electrodes prepared at positive potential limit greater than 1.5 V exhibited enhanced differential pulse voltammetry peak currents, reduced charge transfer resistance, larger effective specific surface area and higher electron transfer rate constant. The composite electrode prepared in the potential range of 0–1.7 V showed optimal electrocatalytic performance. The X-ray photoelectron spectroscopy results indicated that the content of –SO_(2)/–SO and –C=N– groups in the composite film increased significantly after incubation. Further, the Raman spectra and Fourier transform infrared spectra revealed that the thiophene ring structure changed from benzene-type to quinone-type, and the quinone-type pyrrole ring was formed. The electrocatalytic mechanism of the composite film was proposed based on the experimental results and further verified by Density Functional Theory calculation.展开更多
The voltammetric behaviour of uric acid at overoxidized polypyrrole (OPPY ) film-coated glassy carbon (GC ) electrodes was investigaied. The chemically modi- fied electrodes exhilbited an excellent permselectivity for...The voltammetric behaviour of uric acid at overoxidized polypyrrole (OPPY ) film-coated glassy carbon (GC ) electrodes was investigaied. The chemically modi- fied electrodes exhilbited an excellent permselectivity for uric acid of undissociated form in an acidic medium. The current response sensitivity of uric acid at the modi- fied electrodes was markedly increased by properly anodizing activation of underly- ing electrodes and overoxidizing treatment of polypyrrole film. The voltammetric response of uric acid at the chemically modified electrode was linearly related to itinvestigatedtion in the range of 4. 0 ×10-7 -8. 0 ×10-5 mol/L in pH 5 buffer solu- tions. Ascorbic acid in less than 150-fold excess did not interfere with the voltam- metric determination of uric acid. The proposed procedure was utilized to determine uric acicl in human urine and serum samples without any pretreatment.展开更多
A highly selective and sensitive electrochemical method was developed for the detection of serotonin (5-hydroxytryptamine, 5-HT) at gold nanoflowers (Au NFs) and overoxidized polypyrrole (OPPy) modified carbon fiber m...A highly selective and sensitive electrochemical method was developed for the detection of serotonin (5-hydroxytryptamine, 5-HT) at gold nanoflowers (Au NFs) and overoxidized polypyrrole (OPPy) modified carbon fiber microelectrode (CFME). Carbon fiber was firstly modified with gold nanoflowers using electroless deposition method, and then modified with overoxidized polypyrrole using electrochemical polymerization and overoxidization to obtain OPPy/Au NFs/CFME. The obtained OPPy/Au NFs/CFME was characterized by field emission scanning electron microscopy and electrochemical techniques. It was found that the OPPy/Au NFs/CFME showed good sensitivity for the detection of 5-HT in the range of 10 nmol/L-7.0μmol/L with detection limit of 2.3 nmol/L, and negligible interferences from ascorbic acid, 5-hydroxyindole acetic acid and uric acid. The OPPy/Au NFs/CFME was successfully applied to the detection of 5-HT in human serum samples with good recovery. The work demonstrates that the electrochemical method, incorporating signal amplification of Au NFs with higher cation selection of OPPy, provides a promising tool for the detection of 5-HT in biological systems.展开更多
文摘Chloroplast 2-Cys peroxiredoxins （2-Cys Prxs） are efficiently reduced by NADPH Thioredoxin reductase C （NTRC）. To investigate the effect of light/darkness on NTRC function, the content of abundant plastidial enzymes, Rubisco, glutamine synthetase （GS）, and 2-Cys Prxs was analyzed during two consecutive days in Arabidopsis wild-type and ntrc mutant plants. No significant difference of the content of these proteins was observed during the day or the night in wildtype and mutant plants. NTRC deficiency caused a lower content of fully reduced 2-Cys Prxs, which was undetectable in darkness, suggesting that NTRC is the most important pathway for 2-Cys Prx reduction, probably the only one during the night. Arabidopsis contains two plastidial 2-Cys Prxs, A and B, for which T-DNA insertion lines were characterized showing the same phenotype as wild-type plants. Two-dimensional gel analysis of leaf extracts from these mutants allowed the identification of basic and acidic isoforms of 2-Cys Prx A and B. In-vitro assays and mass spectrometry analysis showed that the acidic isoform of both proteins is produced by overoxidation of the peroxidatic Cys residue to sulfinic acid. 2-Cys Prx overoxidation was lower in the NTRC mutant. These results show the important function of NTRC to maintain the redox equilibrium of chloroplast 2-Cys Prxs.
文摘烯烃类化合物,如乙烯和丙烯,是工业生产的关键原料,它们可以通过选择性氧化转化为环氧乙烷(EO)和环氧丙烷(PO)等高附加值的化学品.目前,烯烃类化合物转化主要通过热化学途径实现,通常需要高温高压条件,并可能导致过度氧化生成CO_(2),因而选择性较低,且对经济和环境效益不友好.与此相对,电催化反应以电能作为驱动力,通过优化催化剂、电解液和反应电位等,有望在相对温和的条件下提高反应的选择性和能量效率,为高选择性烯烃氧化提供一种潜在策略.然而,当前烯烃的电化学选择性氧化的电流密度较低,整体生产成本相对较高,因此,有必要进一步研发高效且稳定的电化学选择性氧化烯烃的体系.本文综述了近期关于烯烃选择性电化学氧化的研究进展,研究主要集中在两个方面:一是烯烃在电极和电解液界面上直接进行电化学氧化的方法;二是通过电化学反应原位生成氧化剂(如Cl2和H_(2)O_(2))后,再对烯烃进行氧化的间接方法.对于烯烃的直接电化学氧化,反应的选择性可以通过调控几何效应和电子效应来优化.具体来说,通过引入如氯离子这样的物种,减少催化剂表面的可用活性位点数量,从而降低烯烃在催化剂表面的双位吸附,进一步降低过度氧化的可能性.此外,通过调整电催化剂的电子结构,改变其表面氧物种的电子性质,直接影响烯烃的加氧步骤,从而实现对反应选择性的精准调控.烯烃的氧化过程受限于其固有的缓慢反应动力学,导致直接电氧化所能实现的电流密度有限.为了提高该过程的速率,可以引入氧化还原介导物种来实现烯烃的选择性氧化.近期研究结果表明,卤素和过氧化氢作为介导物种在烯烃的选择性氧化反应中表现较好.利用先进的串联反应器技术,过氧化氢介导乙烯氧化为乙二醇的电流密度已经可以达到500m A cm^(–2).深入探索了烯烃电化�
基金Financial supports from the Natural Science Foundation of Shaanxi Province,China(Grant No.:2020JM-652)Fundamental Research Funds for the Central Universities of Xi’an Jiaotong University(Grant No.:xzy012020054)Cultivation Project of Xi’an Health Committee(Grant No.:2020MS02)。
文摘An innovative,ternary nanocomposite composed of overoxidized poly(3,4-ethylenedioxythiophene)(OPEDOT),gold nanoparticles(Au NPs),and electrochemically reduced graphene oxide(ERGO)was prepared on a glassy carbon electrode(GCE)(OPEDOT-Au NPs-ERGO/GCE)through homogeneous chemical reactions and heterogeneous electrochemical methods.The morphology,composition,and structure of this nanocomposite were characterized by transmission electron microscopy,scanning electron microscopy,X-ray diffraction,and X-ray photoelectron spectroscopy.The electrochemical properties of the OPEDOT-Au NPs-ERGO/GCE were investigated by cyclic voltammetry using potassium ferricyanide and hexaammineruthenium(III)chloride redox probe systems.This modified electrode shows excellent electro-catalytic activity for dopamine(DA)and uric acid(UA)under physiological p H conditions,but inhibits the oxidation of ascorbic acid(AA).Linear voltammetric responses were obtained when DA concentrations of approximately 4.0-100μM and UA concentrations of approximately 20-100μM were used.The detection limits(S/N=3)for DA and UA were 1.0 and 5.0μM,respectively,under physiological conditions and in the presence of 1.0 m M of AA.This developed method was applied to the simultaneous detection of DA and UA in human urine,where satisfactory recoveries from 96.7%to 105.0%were observed.This work demonstrates that the developed OPEDOT-Au NPs-ERGO ternary nanocomposite,with its excellent ion-selectivity and electro-catalytic activity,is a promising candidate for the simultaneous detection of DA and UA in the presence of AA in physiological and pathological studies.
文摘The four-year-old Michelia chapensis, M. platypetala, M. foveolata, and M. maudiae leaves were selected as experimental materials, and their ethanol extracts (light yellow liquid) were obtained by method of organic solvent extraction. The antioxidant components of extracts were initially identified by physical and chemical detection and UV scan. Moreover, the activities of anti-overoxidation for four samples on soybean oil were determined, and PA(phytic acid)and PG(propyl gallate)were contrasted. Besides, the regression models of first-order kinetics for soybean oil samples containing additives were fitted. Results showed that the extraction rate of M. chapensis was the highest (13.24%).The anti-overoxidation components of four samples were flavonoids. According to results of Pf (Oxidation Protection Factor) and determining values of MDA, we found that the capacity of anti-overoxidation for the extract from M. platypetala was the strongest(Pf value 1.25, MDA 0.456). The regression relationships for equations of first-order kinetics were significant. They were suitable to fit exponential function curves. The experiment provides scientific basis for the research and exploration of four Michelia species.
基金support of the Key Research and Development(R&D)Projects of Shanxi Province(Grant No.201903D121114)supported by Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(Grant No.2020L0667).
文摘In this study, a simple and effective method was proposed to improve the electrocatalytic ability of overoxidized poly(3,4-ethylenedioxythiophene)-overoxidized polypyrrole composite films modified on glassy carbon electrode for rutin and luteolin determination. The composite electrode was prepared by cyclic voltammetry copolymerization with LiClO_(4)-water as the supporting electrolyte. The peak current of rutin and luteolin on the composite electrode gradually decreased or even disappeared with the increase in the positive potential limit. After incubation in NaOH–ethanol solution with a volume ratio of 1:1, the composite electrodes prepared at positive potential limit greater than 1.5 V exhibited enhanced differential pulse voltammetry peak currents, reduced charge transfer resistance, larger effective specific surface area and higher electron transfer rate constant. The composite electrode prepared in the potential range of 0–1.7 V showed optimal electrocatalytic performance. The X-ray photoelectron spectroscopy results indicated that the content of –SO_(2)/–SO and –C=N– groups in the composite film increased significantly after incubation. Further, the Raman spectra and Fourier transform infrared spectra revealed that the thiophene ring structure changed from benzene-type to quinone-type, and the quinone-type pyrrole ring was formed. The electrocatalytic mechanism of the composite film was proposed based on the experimental results and further verified by Density Functional Theory calculation.
文摘The voltammetric behaviour of uric acid at overoxidized polypyrrole (OPPY ) film-coated glassy carbon (GC ) electrodes was investigaied. The chemically modi- fied electrodes exhilbited an excellent permselectivity for uric acid of undissociated form in an acidic medium. The current response sensitivity of uric acid at the modi- fied electrodes was markedly increased by properly anodizing activation of underly- ing electrodes and overoxidizing treatment of polypyrrole film. The voltammetric response of uric acid at the chemically modified electrode was linearly related to itinvestigatedtion in the range of 4. 0 ×10-7 -8. 0 ×10-5 mol/L in pH 5 buffer solu- tions. Ascorbic acid in less than 150-fold excess did not interfere with the voltam- metric determination of uric acid. The proposed procedure was utilized to determine uric acicl in human urine and serum samples without any pretreatment.
基金the National Natural Science Foundation of China (Nos. 21775097 and 21804106)the China Postdoctoral Science Foundation (No. 2017M620444)the Fundamental Research Funds for the Central Universities (Nos. XJJ2018247 and GK201801006)
文摘A highly selective and sensitive electrochemical method was developed for the detection of serotonin (5-hydroxytryptamine, 5-HT) at gold nanoflowers (Au NFs) and overoxidized polypyrrole (OPPy) modified carbon fiber microelectrode (CFME). Carbon fiber was firstly modified with gold nanoflowers using electroless deposition method, and then modified with overoxidized polypyrrole using electrochemical polymerization and overoxidization to obtain OPPy/Au NFs/CFME. The obtained OPPy/Au NFs/CFME was characterized by field emission scanning electron microscopy and electrochemical techniques. It was found that the OPPy/Au NFs/CFME showed good sensitivity for the detection of 5-HT in the range of 10 nmol/L-7.0μmol/L with detection limit of 2.3 nmol/L, and negligible interferences from ascorbic acid, 5-hydroxyindole acetic acid and uric acid. The OPPy/Au NFs/CFME was successfully applied to the detection of 5-HT in human serum samples with good recovery. The work demonstrates that the electrochemical method, incorporating signal amplification of Au NFs with higher cation selection of OPPy, provides a promising tool for the detection of 5-HT in biological systems.
