Helicobacter pylori is a highly successful bacterium with a high global prevalence and the infection carries significant disease burden. It is also becoming increasingly difficult to eradicate and the main reason for ...Helicobacter pylori is a highly successful bacterium with a high global prevalence and the infection carries significant disease burden. It is also becoming increasingly difficult to eradicate and the main reason for this is growing primary antibiotic resistance rates in a world where antibiotics are frequently prescribed and readily available. Despite knowing much more about the bacterium since its discovery, such as its genomic makeup and pathogenesis, we have seen declining treatment success. Therefore, clinicians today must be prepared to face one, two or even multiple treatment failures, and should be equipped with sufficient knowledge to decide on the appropriate salvage therapy when this happens. This article discusses the factors contributing to treatment failure and reviews the second and thirdline treatment strategies that have been investigated. Established empiric second line treatment options include both bismuth based quadruple therapy and levofloxacin based triple therapy. Antibiotic testing is recommended prior to initiating third line treatment. In the event that antibiotic susceptibility testing is unavailable, third line treatment options include rifabutin, rifaximin and sitafloxacin based therapies.展开更多
Two rapid, sensitive and reliable immunoassay methods, namely competitive indirect enzyme-linked immunosorbent assay (CI-ELISA) and colloidal gold-based immunochromatographic assay (CGIA), were developed to detect ofl...Two rapid, sensitive and reliable immunoassay methods, namely competitive indirect enzyme-linked immunosorbent assay (CI-ELISA) and colloidal gold-based immunochromatographic assay (CGIA), were developed to detect ofloxacin (OFL). The linear range of the CI-ELISA was from 0.5 to 128 ng/mL with a limit of detection (LOD) of 0.35 ng/mL. Good recoveries were obtained in analyzing simulated swine urine samples. The CGIA could accurately estimate OFL at concentrations as low as 10 ng/mL in less than 10 min, and test results were read visually without any instrument.展开更多
This study aimed to develop hydrophilicmatrix based controlled release gastroretentive drug delivery system of ofloxacin and conducting its in vitro and in vivo evaluations.Effervescent floating gastroretentive drug d...This study aimed to develop hydrophilicmatrix based controlled release gastroretentive drug delivery system of ofloxacin and conducting its in vitro and in vivo evaluations.Effervescent floating gastroretentive drug delivery system of ofloxacin was prepared utilizing Boxe Behnken statistical design with 3 factors,3 levels and 15 experimental trials.Formulation optimization was done by setting targets on selected responses.In vivo studies were carried out for the optimized formulation with 12 healthy human volunteers and obtained pharmacokinetic parameters were compared with themarketed once daily formulation,“Zanocin OD”.Optimized formulation showed satisfactory controlled in vitro drug release for more than 12 h with excellent buoyancy properties(floating lag time<1 min,floating duration>16 h).Optimized and marketed formulations were found to have similar in vitro release profile(f2¼79.22)and also were found to be bioequivalent.Serum ofloxacin concentration was well maintained above its reported minimum inhibitory concentrations for most of the pathogens for sufficiently longer duration.Cmax and AUC values of optimized formulation were found to be significantly higher than of marketed product despite their bioequivalence.Bettertherapeutic effect can be expected since ofloxacin exhibits concentration dependent killing.Hence,gastroretention can be a promising approach to enhance bioavailability of ofloxacin with narrow absorption window in upper GIT.展开更多
A simple,fast and sensitive capillary electrophoresis(CE) strategy combined with chemiluminescence(CL) detection for analysis of ofloxacin(OF) enantiomers was established in the present work.Sulfonated p-cyclode...A simple,fast and sensitive capillary electrophoresis(CE) strategy combined with chemiluminescence(CL) detection for analysis of ofloxacin(OF) enantiomers was established in the present work.Sulfonated p-cyclodextrin(β-CD) was used as the chiral additive being added into the running buffer of luminol-diperiodatocuprate(Ⅲ)(K[Cu(HIO6)2],DPC) chemiluminescence system.Under the optimum conditions,the proposed method was successfully applied to separation and analysis of OF enantiomers with the detection limits(S/N=3) of 8.0 nM and 7.0 nM for levofloxacin and dextrofloxacin,respectively.The linear ranges were both 0.010-100 μM.The method was utilized for analyzing OF in urine;the results obtained were satisfactory and recoveries were 89.5-110.8%,which demonstrated the reliability of this method.This approach can also be further extended to analyze different commercial OF medicines.展开更多
Nanocomposites were prepared by blending soy protein isolate with different percentage of MMT by melt extrusion technique. The nanocomposites were characterized by using, XRD, TEM, SEM and TGA methods. The XRD studies...Nanocomposites were prepared by blending soy protein isolate with different percentage of MMT by melt extrusion technique. The nanocomposites were characterized by using, XRD, TEM, SEM and TGA methods. The XRD studies indicated the absence of diffraction peaks for the bio-nanocomposites. From the TEM studies it was ascertained that the degree of exfoliation increased with increase in MMT content. The morphology of the nanocomposites was ascertained from the SEM studies. The degradation pattern of the nano-composites was evaluated from the TG analysis. The drug delivery system of the nanocmposites was investigated by blending the nanocomposites with ofloxacin at different pH media. The various kinetic parameters were evaluated and the mechanism of drug delivery has been postulated based on the kinetic data.展开更多
70 clinical Mycobacterium tuberculosis strains isolated from AIDS patients in two HIV/AIDS referral hospitals in Beijing were used in this study.M.tuberculosis and non-tuberculosis mycobacterium(NTM)were identified ...70 clinical Mycobacterium tuberculosis strains isolated from AIDS patients in two HIV/AIDS referral hospitals in Beijing were used in this study.M.tuberculosis and non-tuberculosis mycobacterium(NTM)were identified by using multi-locus PCR.M.tuberculosis was genotyped by using 15-locus MIRU-VNTR technique and spoligotyping afterwards.Meanwhile,the drug susceptibilities of the strains to the four first-line anti TB drugs(rifampin,isoniazid,streptomycin, and ethambutol) and the four second-line anti-TB drugs (capreomycin, kanamycin, ofloxacin, and ethionanide) were tested with proportional method. In this study, M. tuberculosis and NTM strains isolated from AIDS patients with TB-like symptoms were identified and genotyping analysis indicated that Beijing genotype was the predominant genotype. In addition, the prevalence of drug-resistant TB, especially the prevalence of XDR-TB, was higher than that in TB patients without HIV infection.展开更多
The objective of this study was to carry out taste masking of ofloxacin(Ofl) by ion exchange resins(IERs)followed by sustained release of Ofl by forming interpenetrating polymer network(IPN) beads. Drug-resin complexe...The objective of this study was to carry out taste masking of ofloxacin(Ofl) by ion exchange resins(IERs)followed by sustained release of Ofl by forming interpenetrating polymer network(IPN) beads. Drug-resin complexes(DRCs) with three different ratios of Ofl to IERs(1:1, 1:2, 1:4) were prepared by batch method and investigated for in vivo and in vitro taste masking. DRC of methacrylic acid-divinyl benzene(MD) resin and Ofl prepared at a ratio of 1:4 was used to form IPN beads. IPN beads of MD 1:4 were prepared by following the ionic cross-linking method using sodium carboxymethyl xanthan gum(SCMXG) and SCMXG-sodium carboxymethyl cellulose(SCMXG-SCMC). IPN beads were characterized with FT-IR and further studied on sustained release of Ofl at different pH. In vivo taste masking carried out by human volunteers showed that MD 1:4 significantly reduced the bitterness of Ofl. Characterization studies such as FT-IR, DSC, P-XRD and taste masking showed that complex formation took place between drug and resin. In vitro study at gastric pH showed complete release of drug from MD 1:4 within 30 min whereas IPN beads took 5 h at gastric pH and 10 h at salivary pH for the complete release of drug. As the crosslinking increased the release kinetics changed into non-Fickian diffusion to zero-order release mechanism. MD 1:4 showed better performance for the taste masking of Ofl and IPNs beads prepared from it were found useful for the sustained release of Ofl at both the pH, indicating a versatile drug delivery system.展开更多
Background: Extensively drug resistant tuberculosis (XDR-TB) is a serious problem in public health and XDR-TB patients usually develop from multi-drug resistance tuberculosis (MDR-TB) and pre-XDR-TB. The rapid molecul...Background: Extensively drug resistant tuberculosis (XDR-TB) is a serious problem in public health and XDR-TB patients usually develop from multi-drug resistance tuberculosis (MDR-TB) and pre-XDR-TB. The rapid molecular test for drug susceptibility testing (DST) can be used for early detection to prevent XDR-TB. Methods: We examined 34 clinical Mycobacterium tuberculosis (M. tuberculosis) isolates from MDR/XDR-TB patients in the upper north of Thailand that were identified with drug susceptibility profiles by indirect agar proportion method from 2005-2012. Our study investigated the genetic mutations in gyrA for ofloxacin resistance and rrs for kanamycin resistance. The genetic mutations and drug susceptibility test results were analyzed using the exact test. Results: The majority of the ofloxacin resistance was detected in gyrA 21, gyrA 70, gyrA 87, gyrA 102, gyrA 162, and gyrA 187 were at 0%, 12.5%, 37.5%, 0%, 50.0% and 25.0% sensitivity, respectively, and at 96.2, 96.2%, 20.1%, 96.2%, 57.7% and 61.5% specificity, respectively. Kanamycin resistance was found in rrs 512, rrs 241, rrs 223, rrs 414 and rrs 408 at 16.7%, 0%, 0%, 16.7% and 16.7% sensitivity, respectively, and at 96.4%, 92.9%, 82.1%, 82.1% and 71.4% specificity, respectively. This study found no significant correlation between gyrA mutations and ofloxacin resistance and also no correlation between the rrs gene and kanamycin resistance. Conclusion: These primer sequences and PCR products in our study such as gyrA and rrs might be unsuitable to detect ofloxacin and kanamycin resistance in the upper north of Thailand.展开更多
Ofloxacin is an antibiotic with a wide range of activity against bacterial infections, but due to the high potential for toxicity when exposed to light, resolving this problem and further stabilizing the drug are amon...Ofloxacin is an antibiotic with a wide range of activity against bacterial infections, but due to the high potential for toxicity when exposed to light, resolving this problem and further stabilizing the drug are among the posed challenges. Inclusion complex formation between α-cyclodextrin (α-CD), ofloxacin (OFL) and polyethylene glycol (PEG) was prepared via two methods to produce nanocontainers with desirable stability. The effect of PEG as compatible solubilizing agent and mixing condition (in ultrasonic bath) were investigated in formation of an inclusion complex between α-CD/OFL. Obtained complexes were examined by FTIR, H-NMR, SEM, EDX and UV which indicated the formation of an inclusion complex between α-CD/OFL, in turn, is a mixture of the cage and channel structures. Differences between 1H-NMR, FTIR and XRD spectra of OFL, CDs and inclusion complex indicated the formation of α-CD/OFL and supramolecular containers in solid phase. These inclusion complexes loaded in PVA-based nanofibers for smart nanofibers with controlled release manner and higher stability of OFL. Obtained nanofiber showed that nanofibers containing CDs/OFL under sonic energy containing higher degree of OFL.展开更多
920038 Clinical effect and laboratoryobservation of ofloxacin in the treatment oftyphoid fever,bacillary dysentery and gonor-rhea.ZOU Qiyuan (邹启园),et al.Dept InfectDis,1st Affil Hosp,Chongqing Med Univ,630042.Chin ...920038 Clinical effect and laboratoryobservation of ofloxacin in the treatment oftyphoid fever,bacillary dysentery and gonor-rhea.ZOU Qiyuan (邹启园),et al.Dept InfectDis,1st Affil Hosp,Chongqing Med Univ,630042.Chin J Intern Med 1991;30 (9)展开更多
Nitrogen-rich graphitized carbon microspheres(NGCs)with hierarchically porous were constructed by self-assembly.Under different heat treatment conditions,the structure,morphology and properties of NGCs were studied by...Nitrogen-rich graphitized carbon microspheres(NGCs)with hierarchically porous were constructed by self-assembly.Under different heat treatment conditions,the structure,morphology and properties of NGCs were studied by using multiple characterization techniques.The results showed that the chemical microenvironments(e.g.surface chemistry,degree of graphitization and defective,etc.)and microstructures properties(e.g.morphology,specific surface area,particle size,etc.)could be delicately controlled via thermal carbonization processes.The degradation of ofloxacin(OFLX)by NGCs activated peroxymonosulfate(PMS)was studied systematically.It was found that the synergistic coupling effect between optimum N or O bonding species configuration ratio(graphitic N and C=O)and special microstructure was the main reason for the enhanced catalytic activity of NGC-800(calcination temperature at 800°C).Electron paramagnetic resonance(EPR)experiments and radical quenching experiments indicated that the hydroxyl(·OH),sulfate(SO4^·-)and singlet oxygen(^1O_(2))were contributors in the NGC-800/PMS systems.Further investigation of the durability of chemical structures and surface active sites revealed that undergo N bonding species configuration reconstruction and cannibalistic oxidation during PMS activation reaction.The used NGC-800 physicochemical properties could be recovered by heat treatment to achieve the ideal catalytic performance.The findings proposed a valuable insight for catalytic performance and controllable design of construction.展开更多
Cu2O/nitrogen-doped grapheme(NG) nanocomposite material was prepared via a facile one step chemical reduction and characterized by means of X-ray diffraction(XRD) and scanning electron microscopy(SEM). A new ele...Cu2O/nitrogen-doped grapheme(NG) nanocomposite material was prepared via a facile one step chemical reduction and characterized by means of X-ray diffraction(XRD) and scanning electron microscopy(SEM). A new electrochemical sensor was then fabricated by coating Cu2O/nitrogen-doped graphene nanocomposite with Nation on glassy carbon electrode(Cu2O/NG/Nation/GCE). The electrochemical response of this modified electrode toward of- loxacin was examined by cyclic voltammetry. The results indicate that Cu2O/NG/Nafion composite-modified elec- trode exhibits higher catalytic activity in the electrochemical oxidation of ofloxacin compared with glassy carbon electrode(GCE), Cu2O/Nafion modified electrode(Cu2O/Nafion/GCE), and N-doped graphene/Nation modified electrode(NG/Nafion/GCE). Under optimal conditions, the peak current was found to be linearly proportional to the concentration of ofloxacin in the 0.5-27.5 μmol/L and 27.5-280 μmol/L ranges with a lower detection limit of 0.34 μmol/L, higher sensitivity of 39.32 μA-L-mmoV1 and a shorter reaction time of less than 2 s. In addition, Nation can enhance the stability of the modified electrode and prevent some negative species. Thus the modified electrode exhibits good selectivity and a long working life. The Cu2O/NG/Nafion composite modified electrode shows promising application in electrochemical sensors, biosensors, and other related fields because of its excellent properties.展开更多
文摘Helicobacter pylori is a highly successful bacterium with a high global prevalence and the infection carries significant disease burden. It is also becoming increasingly difficult to eradicate and the main reason for this is growing primary antibiotic resistance rates in a world where antibiotics are frequently prescribed and readily available. Despite knowing much more about the bacterium since its discovery, such as its genomic makeup and pathogenesis, we have seen declining treatment success. Therefore, clinicians today must be prepared to face one, two or even multiple treatment failures, and should be equipped with sufficient knowledge to decide on the appropriate salvage therapy when this happens. This article discusses the factors contributing to treatment failure and reviews the second and thirdline treatment strategies that have been investigated. Established empiric second line treatment options include both bismuth based quadruple therapy and levofloxacin based triple therapy. Antibiotic testing is recommended prior to initiating third line treatment. In the event that antibiotic susceptibility testing is unavailable, third line treatment options include rifabutin, rifaximin and sitafloxacin based therapies.
文摘Two rapid, sensitive and reliable immunoassay methods, namely competitive indirect enzyme-linked immunosorbent assay (CI-ELISA) and colloidal gold-based immunochromatographic assay (CGIA), were developed to detect ofloxacin (OFL). The linear range of the CI-ELISA was from 0.5 to 128 ng/mL with a limit of detection (LOD) of 0.35 ng/mL. Good recoveries were obtained in analyzing simulated swine urine samples. The CGIA could accurately estimate OFL at concentrations as low as 10 ng/mL in less than 10 min, and test results were read visually without any instrument.
文摘This study aimed to develop hydrophilicmatrix based controlled release gastroretentive drug delivery system of ofloxacin and conducting its in vitro and in vivo evaluations.Effervescent floating gastroretentive drug delivery system of ofloxacin was prepared utilizing Boxe Behnken statistical design with 3 factors,3 levels and 15 experimental trials.Formulation optimization was done by setting targets on selected responses.In vivo studies were carried out for the optimized formulation with 12 healthy human volunteers and obtained pharmacokinetic parameters were compared with themarketed once daily formulation,“Zanocin OD”.Optimized formulation showed satisfactory controlled in vitro drug release for more than 12 h with excellent buoyancy properties(floating lag time<1 min,floating duration>16 h).Optimized and marketed formulations were found to have similar in vitro release profile(f2¼79.22)and also were found to be bioequivalent.Serum ofloxacin concentration was well maintained above its reported minimum inhibitory concentrations for most of the pathogens for sufficiently longer duration.Cmax and AUC values of optimized formulation were found to be significantly higher than of marketed product despite their bioequivalence.Bettertherapeutic effect can be expected since ofloxacin exhibits concentration dependent killing.Hence,gastroretention can be a promising approach to enhance bioavailability of ofloxacin with narrow absorption window in upper GIT.
基金financially supported by the Natural Science Foundation of Chongqing(CSTC2013jjB0096)the Fundamental Research Funds for the Central Universities(XDJK2012A002 and XDJK2013A025)the Program for Innovative Research Team in University of Chongqing(2013)
文摘A simple,fast and sensitive capillary electrophoresis(CE) strategy combined with chemiluminescence(CL) detection for analysis of ofloxacin(OF) enantiomers was established in the present work.Sulfonated p-cyclodextrin(β-CD) was used as the chiral additive being added into the running buffer of luminol-diperiodatocuprate(Ⅲ)(K[Cu(HIO6)2],DPC) chemiluminescence system.Under the optimum conditions,the proposed method was successfully applied to separation and analysis of OF enantiomers with the detection limits(S/N=3) of 8.0 nM and 7.0 nM for levofloxacin and dextrofloxacin,respectively.The linear ranges were both 0.010-100 μM.The method was utilized for analyzing OF in urine;the results obtained were satisfactory and recoveries were 89.5-110.8%,which demonstrated the reliability of this method.This approach can also be further extended to analyze different commercial OF medicines.
文摘Nanocomposites were prepared by blending soy protein isolate with different percentage of MMT by melt extrusion technique. The nanocomposites were characterized by using, XRD, TEM, SEM and TGA methods. The XRD studies indicated the absence of diffraction peaks for the bio-nanocomposites. From the TEM studies it was ascertained that the degree of exfoliation increased with increase in MMT content. The morphology of the nanocomposites was ascertained from the SEM studies. The degradation pattern of the nano-composites was evaluated from the TG analysis. The drug delivery system of the nanocmposites was investigated by blending the nanocomposites with ofloxacin at different pH media. The various kinetic parameters were evaluated and the mechanism of drug delivery has been postulated based on the kinetic data.
基金funded by(2013ZX10003006-002-001 and 2011ZX10004-001)National Key Program of Mega Infectious DiseaseNational Natural Science Foundation(30973388)Capital Medical Development Scientific Research Fund(2009-1057)
文摘70 clinical Mycobacterium tuberculosis strains isolated from AIDS patients in two HIV/AIDS referral hospitals in Beijing were used in this study.M.tuberculosis and non-tuberculosis mycobacterium(NTM)were identified by using multi-locus PCR.M.tuberculosis was genotyped by using 15-locus MIRU-VNTR technique and spoligotyping afterwards.Meanwhile,the drug susceptibilities of the strains to the four first-line anti TB drugs(rifampin,isoniazid,streptomycin, and ethambutol) and the four second-line anti-TB drugs (capreomycin, kanamycin, ofloxacin, and ethionanide) were tested with proportional method. In this study, M. tuberculosis and NTM strains isolated from AIDS patients with TB-like symptoms were identified and genotyping analysis indicated that Beijing genotype was the predominant genotype. In addition, the prevalence of drug-resistant TB, especially the prevalence of XDR-TB, was higher than that in TB patients without HIV infection.
基金Council of Scientific and Industrial Research (CSIR), New Delhi, India, for providing Senior Research FellowshipCentralized Analytical Facility of CSIRCSMCRI for analytical support
文摘The objective of this study was to carry out taste masking of ofloxacin(Ofl) by ion exchange resins(IERs)followed by sustained release of Ofl by forming interpenetrating polymer network(IPN) beads. Drug-resin complexes(DRCs) with three different ratios of Ofl to IERs(1:1, 1:2, 1:4) were prepared by batch method and investigated for in vivo and in vitro taste masking. DRC of methacrylic acid-divinyl benzene(MD) resin and Ofl prepared at a ratio of 1:4 was used to form IPN beads. IPN beads of MD 1:4 were prepared by following the ionic cross-linking method using sodium carboxymethyl xanthan gum(SCMXG) and SCMXG-sodium carboxymethyl cellulose(SCMXG-SCMC). IPN beads were characterized with FT-IR and further studied on sustained release of Ofl at different pH. In vivo taste masking carried out by human volunteers showed that MD 1:4 significantly reduced the bitterness of Ofl. Characterization studies such as FT-IR, DSC, P-XRD and taste masking showed that complex formation took place between drug and resin. In vitro study at gastric pH showed complete release of drug from MD 1:4 within 30 min whereas IPN beads took 5 h at gastric pH and 10 h at salivary pH for the complete release of drug. As the crosslinking increased the release kinetics changed into non-Fickian diffusion to zero-order release mechanism. MD 1:4 showed better performance for the taste masking of Ofl and IPNs beads prepared from it were found useful for the sustained release of Ofl at both the pH, indicating a versatile drug delivery system.
文摘Background: Extensively drug resistant tuberculosis (XDR-TB) is a serious problem in public health and XDR-TB patients usually develop from multi-drug resistance tuberculosis (MDR-TB) and pre-XDR-TB. The rapid molecular test for drug susceptibility testing (DST) can be used for early detection to prevent XDR-TB. Methods: We examined 34 clinical Mycobacterium tuberculosis (M. tuberculosis) isolates from MDR/XDR-TB patients in the upper north of Thailand that were identified with drug susceptibility profiles by indirect agar proportion method from 2005-2012. Our study investigated the genetic mutations in gyrA for ofloxacin resistance and rrs for kanamycin resistance. The genetic mutations and drug susceptibility test results were analyzed using the exact test. Results: The majority of the ofloxacin resistance was detected in gyrA 21, gyrA 70, gyrA 87, gyrA 102, gyrA 162, and gyrA 187 were at 0%, 12.5%, 37.5%, 0%, 50.0% and 25.0% sensitivity, respectively, and at 96.2, 96.2%, 20.1%, 96.2%, 57.7% and 61.5% specificity, respectively. Kanamycin resistance was found in rrs 512, rrs 241, rrs 223, rrs 414 and rrs 408 at 16.7%, 0%, 0%, 16.7% and 16.7% sensitivity, respectively, and at 96.4%, 92.9%, 82.1%, 82.1% and 71.4% specificity, respectively. This study found no significant correlation between gyrA mutations and ofloxacin resistance and also no correlation between the rrs gene and kanamycin resistance. Conclusion: These primer sequences and PCR products in our study such as gyrA and rrs might be unsuitable to detect ofloxacin and kanamycin resistance in the upper north of Thailand.
文摘Ofloxacin is an antibiotic with a wide range of activity against bacterial infections, but due to the high potential for toxicity when exposed to light, resolving this problem and further stabilizing the drug are among the posed challenges. Inclusion complex formation between α-cyclodextrin (α-CD), ofloxacin (OFL) and polyethylene glycol (PEG) was prepared via two methods to produce nanocontainers with desirable stability. The effect of PEG as compatible solubilizing agent and mixing condition (in ultrasonic bath) were investigated in formation of an inclusion complex between α-CD/OFL. Obtained complexes were examined by FTIR, H-NMR, SEM, EDX and UV which indicated the formation of an inclusion complex between α-CD/OFL, in turn, is a mixture of the cage and channel structures. Differences between 1H-NMR, FTIR and XRD spectra of OFL, CDs and inclusion complex indicated the formation of α-CD/OFL and supramolecular containers in solid phase. These inclusion complexes loaded in PVA-based nanofibers for smart nanofibers with controlled release manner and higher stability of OFL. Obtained nanofiber showed that nanofibers containing CDs/OFL under sonic energy containing higher degree of OFL.
文摘920038 Clinical effect and laboratoryobservation of ofloxacin in the treatment oftyphoid fever,bacillary dysentery and gonor-rhea.ZOU Qiyuan (邹启园),et al.Dept InfectDis,1st Affil Hosp,Chongqing Med Univ,630042.Chin J Intern Med 1991;30 (9)
基金the National Natural Science Foundation of China(No.51578295)the National Natural Science Foundation of Jiangsu Province(No.BK20161479)+3 种基金Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse(Nanjing University of Science and Technology)Qinglan Project of Jiangsu Province supported this studyFoundation of Jiangsu Collaborative Innovation Center of Biomedical Functional Materialsa project funded by the priority academic program development of Jiangsu Higher Education Institutions。
文摘Nitrogen-rich graphitized carbon microspheres(NGCs)with hierarchically porous were constructed by self-assembly.Under different heat treatment conditions,the structure,morphology and properties of NGCs were studied by using multiple characterization techniques.The results showed that the chemical microenvironments(e.g.surface chemistry,degree of graphitization and defective,etc.)and microstructures properties(e.g.morphology,specific surface area,particle size,etc.)could be delicately controlled via thermal carbonization processes.The degradation of ofloxacin(OFLX)by NGCs activated peroxymonosulfate(PMS)was studied systematically.It was found that the synergistic coupling effect between optimum N or O bonding species configuration ratio(graphitic N and C=O)and special microstructure was the main reason for the enhanced catalytic activity of NGC-800(calcination temperature at 800°C).Electron paramagnetic resonance(EPR)experiments and radical quenching experiments indicated that the hydroxyl(·OH),sulfate(SO4^·-)and singlet oxygen(^1O_(2))were contributors in the NGC-800/PMS systems.Further investigation of the durability of chemical structures and surface active sites revealed that undergo N bonding species configuration reconstruction and cannibalistic oxidation during PMS activation reaction.The used NGC-800 physicochemical properties could be recovered by heat treatment to achieve the ideal catalytic performance.The findings proposed a valuable insight for catalytic performance and controllable design of construction.
基金Supported by the National Natural Science Foundation of China(Nos.21071005, 21271006), the Natural Science Foundation of the Education Bureau of Anhui Province, China(No.KJ2015A024) and the Graduate Student Innovation Fund of Anhui University of Technology, China(No.2014033).
文摘Cu2O/nitrogen-doped grapheme(NG) nanocomposite material was prepared via a facile one step chemical reduction and characterized by means of X-ray diffraction(XRD) and scanning electron microscopy(SEM). A new electrochemical sensor was then fabricated by coating Cu2O/nitrogen-doped graphene nanocomposite with Nation on glassy carbon electrode(Cu2O/NG/Nation/GCE). The electrochemical response of this modified electrode toward of- loxacin was examined by cyclic voltammetry. The results indicate that Cu2O/NG/Nafion composite-modified elec- trode exhibits higher catalytic activity in the electrochemical oxidation of ofloxacin compared with glassy carbon electrode(GCE), Cu2O/Nafion modified electrode(Cu2O/Nafion/GCE), and N-doped graphene/Nation modified electrode(NG/Nafion/GCE). Under optimal conditions, the peak current was found to be linearly proportional to the concentration of ofloxacin in the 0.5-27.5 μmol/L and 27.5-280 μmol/L ranges with a lower detection limit of 0.34 μmol/L, higher sensitivity of 39.32 μA-L-mmoV1 and a shorter reaction time of less than 2 s. In addition, Nation can enhance the stability of the modified electrode and prevent some negative species. Thus the modified electrode exhibits good selectivity and a long working life. The Cu2O/NG/Nafion composite modified electrode shows promising application in electrochemical sensors, biosensors, and other related fields because of its excellent properties.