Recently increasing concerns from the scientists and public have been paid for seawater pollution due to tetracycline(TC)overuse in maricultural area.However,there are few methods or instruments that can be used for s...Recently increasing concerns from the scientists and public have been paid for seawater pollution due to tetracycline(TC)overuse in maricultural area.However,there are few methods or instruments that can be used for specific and rapid detection of this antibiotic in seawater.In this study,the colloidal gold immunochromatographic assay(CG-ICA)was used to achieve this goal.A commercialized monoclonal antibody against TC(anti-TC mAb)was selected because of its higher sensitivity(half-maximal inhibitory concentration of 2.38μgL^(-1)).The prepared CG particles(average diameter of 20 nm)were used to label anti-TC mAb at pH 8.0.The conjugate pad was formed by spraying the CG-labeled anti-TC mAb on a glass fibre membrane followed by proper dryness.The test pad was made by immobilizing artificial antigen and anti-mouse mAb in the test line and the control line,respectively,in a nitrocellulose membrane.The test strip,assembled with sample pad,conjugate pad,test pad and absorbent pad,could be used to detect TC during seawater sample flowing through these components in turn.The results could be observed by the naked eye in 10min.The visible limit of detection(vLOD)was 20μgL^(-1) for TC in seawater.The CG-ICA test results were in good agreement with those of liquid chromatography-tandem mass spectrometry(LC-MS/MS).The assay also showed that,oxytetracycline(OTC)and chlortetracycline(CTC),as the structural analogues of TC,did not interfere with TC determination.Furthermore,the TC concentration given by test strip could not be affected by the fluctuation of temperature(10℃–30℃),pH(7–9)and salinity(0–40)of seawater.Therefore,CG-ICA is a suitable tool for rapid,on-site,and semi-quantitative detection of TC in seawater.展开更多
Methamidophos (Met) is a broad spectrum organophosphorus insecticide and acaricide.Even a trace of its residue is harmful to humans and many animals.In this study,the synthesis and identification of colloidal gold par...Methamidophos (Met) is a broad spectrum organophosphorus insecticide and acaricide.Even a trace of its residue is harmful to humans and many animals.In this study,the synthesis and identification of colloidal gold particles and antibody-colloidal gold conjugates were performed,and the preparation of colloidal gold immunochromatography strip was conducted for detection of Met residue.The size of colloidal gold particles was checked using a transmission electron microscope (TEM).The formation of antibody-coll...展开更多
A method for the determination of human immunoglobulin G(IgG) based on a colloidal gold label by fluorospectrophotometry was developed. The sandwich immunoreaction among goat-anti-human IgG, human IgG and goat-anti-...A method for the determination of human immunoglobulin G(IgG) based on a colloidal gold label by fluorospectrophotometry was developed. The sandwich immunoreaction among goat-anti-human IgG, human IgG and goat-anti-human IgG labeled with colloidal gold nanoparticles was applied in this experiment. First, a sandwich im- munocomplex was formed on the surface of 96 well clear polystyrene high bind stripwellTM microplate. After the formation of the sandwich immunocomplex, a solution was added to dissociate the immunocomplex at room temperature. Then the solution of each well was transferred into the corresponding test tube. Thirdly, the rhodamine B solution was injected into each test tube. The rhodamine B chloraurate was extracted into ether that was measured with a spectrofluorometer. The experimental results indicate that the fluorescence intensity increased with the increase of human IgG concentration. The fluorescence intensity of rhodamine B chloraurate at 570 nm was proportional to the logarithm of human IgG concentration in a range from 10 to 5 × 10^5 ng/mL. It was shown that the determination of human IgG was easily made with the proposed fluorospectrophotometry.展开更多
A sandwich format immunochromatographic assay for detecting foot-and-mouth disease virus (FMDV) serotypes was developed. In this rapid test,affinity purified polyclonal antibodies from Guinea pigs which were immunized...A sandwich format immunochromatographic assay for detecting foot-and-mouth disease virus (FMDV) serotypes was developed. In this rapid test,affinity purified polyclonal antibodies from Guinea pigs which were immunized with sucking-mouse adapted FMD virus (A/AV88(L) strain) were conjugated to colloidal gold beads and used as the capture antibody,and affinity purified polyclonal antibodies from rabbits which were immunized with cell-culture adapted FMD virus (A/CHA/09 strain) were used as detector antibody. On the nitrocellulose membrane of the immunochromatographic strip,the capture antibody was laid on a sample pad,the detector antibody was printed at the test line(T) and goat anti-guinea pigs IgG antibodies were immobilized to the control line(C). The lower detection limit of the test for a FMDV 146S antigen is 11.7ng/ml as determined in serial tests after the strip device was assembled and the assay condition optimization. No cross reactions were found with FMDV serotype C,Swine vesicular disease (SVD),Vesicular stomatiti svirus (VSV) and vesicular exanthema of swine virus (VES) viral antigens with this rapid test. Clinically,the diagnostic sensitivity of this test for FMDV serotypes A was 88.7% which is as same as an indirect-sandwich ELISA. The specificity of this strip test was 98.2% and is comparable to the 98.7% obtained with indirect-sandwich ELISA. This rapid strip test is simple,easy and fast for clinical testing on field sites; no special instruments and skills are required,and the result can be obtained within 15 min. To our knowledge,this is the first rapid immunochromatogarpic assay for serotype A of FMDV.展开更多
Colloidal gold immunochromatographic assay(CGIA)is commonly used for the on-site detection ofβ-agonists that are sometimes used illegally as feed additives in swine diets.However,few studies have evaluated the causes...Colloidal gold immunochromatographic assay(CGIA)is commonly used for the on-site detection ofβ-agonists that are sometimes used illegally as feed additives in swine diets.However,few studies have evaluated the causes of false-positive results that sometimes occur when applying CGIA in agricultural settings.In this study,we investigated if this false-positive phenomenon is related to the addition of certain traditional Chinese medicines(TCMs)to swine feed.We established and verified an extraction method for TCMs,and then applied CGIA to detectβ-agonists in the extracts of 105 TCMs and in the urine of swine dosed with TCMs,respectively.Liquid chromatography-tandem mass spectrometry was used to validate the results of the urine samples tested positive forβ-agonists using CGIA.The results were also verified using TCMs and colloidal gold test strips produced by different manufacturers.The extracts of Citri Reticulatae Pericarpium Viride,Citri Reticulatae Pericarpium,Magnoliae Officinalis Cortex,Chaenomelis Fructus,and Rhodiolae Crenulatae Radix Et Rhizoma were tested positive forβ-agonists.Meanwhile,the addition of Citri Reticulatae Pericarpium Viride and Citri Reticulatae Pericarpium to swine feed resulted in false-positive results forβ-agonists in swine urine.The results provide a new way to explain false-positive CGIA results and provide valuable information for livestock feeding programs.展开更多
The distribution of gold colloids in kaolinite and the interaction between gold and kaolinite surface were investigated by transmission electron mieroscotgy (TEM) and X-ray photoelectron spectroscopy ( XPS ). The...The distribution of gold colloids in kaolinite and the interaction between gold and kaolinite surface were investigated by transmission electron mieroscotgy (TEM) and X-ray photoelectron spectroscopy ( XPS ). There is strong interaction between the gold particles and the edge surfaces of kaolinite, in low pH solution, the edge surface of kaolinite is positively charged and electrostutic attrcactive force between colloide gold panicles and the positive edge surface of kaolinite woald facilitate the adsorption of colloidal gold particles onto the suface. TEM observation shows that the aggregate morphology of gold particles was dominated by particle-particle interaction and gold particles were adsorbed on the edge surface of kaolinite crystals , resulting from the electrostatic attractive force between colloidal gold particles and the positice surfaces of kaolinite. XPS data show that in Au4 f electron spectra there are four energy peaks related to gold, 83.8 eV, 85.7 eV, 87.5 eV, and 89.4 eV, respectively, which suggests that in chemical states there are metallic gold and Au bonded to O, similar to the form of Au2O3 , and composite Au2O3 is formed between the edge surface of kaolinite and colloidal gold surface.展开更多
A test strip was developed to rapidly detect fluoroquinolones in foods by colloidal gold immunochromatography method in combination with a food safety analyzer. The results showed that the test strip has the detection...A test strip was developed to rapidly detect fluoroquinolones in foods by colloidal gold immunochromatography method in combination with a food safety analyzer. The results showed that the test strip has the detection sensitivity of 20 μg/L for enrofloxacin, sarafloxacin, difloxacin, ofloxacin, norfloxacin, ciprofloxacin, pefloxacin, flumequine and danofloxacin, and the detection sensitivity of 40 μg/L for enoxacin and oxolinic acid. The test strip consumes only 10 min for detection, and the false positive rate and the false negative rate are both zero. The test strip can accurately, reliably and easily detect residual fluoroquinolones in foods, and is suitable for on-site detection of a large number of samples.展开更多
Objective: p195, the major protein on the surface of Plasmodium falciparum merozoites, has been found to have ability to bind sialic acid residues on the surface of human erythrocytes, and this binding is thought to b...Objective: p195, the major protein on the surface of Plasmodium falciparum merozoites, has been found to have ability to bind sialic acid residues on the surface of human erythrocytes, and this binding is thought to be a prerequisite for recognition of human erythrocyte by merozoite- This study attempted to map out the binding site of p195, thus providing a theoretical clue to developing an antimalaria vaccine which blockades invasion of merozoites into human erythrocytes. Methods: Eight proteins derived from pl95 were expressed in E. coli, and purified by Ni-chelate affinity chromatography. The re folded proteins were labelled with colloidal gold. The labelled protein complexes were co-incubated with human erythrocytes separately and simultaneously, and the proteins were put into the culture supernatant of P- falciParum to observe their effect on invasion of merozoites into erythrocytes. Results: A fragment of p195, M6 (amino acid sequence: 384 - 595), was found to have the ability to bind human erythrocytes. M6 gold complexes showed no ability to bind erythrocytes treated with trypsin or neuraminidase. M6 was also found to have the ability to inhibit invasion of merozoites of P. falciparym into human erythrocytes. Conclusiou: A fragment of p195, M6, has the ability to bind human erythrocytes. The binding is dependent on sialic acid residues, and may be a prerequisite to recognition of erythrocytes by merozoites.展开更多
A comprehensive investigation on the formation mechanism of gold nanoparticles (AuNPs) in colloidal mixture obtained from the reduction of chloroauric acid (HAuCl4) solution using a single reducing agent (sodium citra...A comprehensive investigation on the formation mechanism of gold nanoparticles (AuNPs) in colloidal mixture obtained from the reduction of chloroauric acid (HAuCl4) solution using a single reducing agent (sodium citrate;process-I), (tannic acid;process-II), and a combination of two reducing agents (sodium citrate plus tannic acid;process-III) is reported. The growth steps at different time intervals during synthesis of colloidal AuNPs were monitored in situ and ex situ using various methods for all the three processes. The measurement of changes in the surface plasmon band position of colloidal AuNPs, along with dynamic light scattering results gave important information for the first assessing of particle size, shape and distribution. Besides, the size and morphological changes at different stages during different processes were also analyzed by transmission electron microscopy. The final Au particles of processes-I & II exhibited different shapes (spherical and nanowires) with particle size and nano wire diameter of 12 nm and 17 nm, respectively. Nevertheless, combination of two reductants (process-III) surprisingly leads to drastically reduced size (ca. 3 nm) with spherical morphology compared to their parent solutions with either of single reducing agent. This result clearly indicates that the combination of reductants has a significant influence on the particle size, morphology and formation mechanism.展开更多
Narrow disperse poly(ethyleneglycol dimethacrylate-co-4-vinylpyridine) (poly(EGDMA-co-4-VPy)) microspheres were prepared by distillation-precipitation copolymerization of ethyleneglycol dimethacrylate (EGDMA) ...Narrow disperse poly(ethyleneglycol dimethacrylate-co-4-vinylpyridine) (poly(EGDMA-co-4-VPy)) microspheres were prepared by distillation-precipitation copolymerization of ethyleneglycol dimethacrylate (EGDMA) and 4-vinylpyridine (4-VPy) with 2,2'-azobisisobutyronitrile (AIBN) as initiator in neat acetonitrile. The polymer microspheres containing pyridyl group were then utilized as stabilizer for gold metallic colloids with the diameter around 7 nm, which were prepared by the in situ reduction of gold chloride trihydrate with sodium borohydride through the coordination of the pyridyl group on the gel layer and surface of the microsphere with the gold metallic nano-particles. The catalytic properties of the pyridyl- functionalized microsphere-stabilized gold metallic colloids and the behavior of the stabilized-catalyst for the recycling were investigated with reduction of 4-nitrophenol to 4-aminophenol as a model reaction.展开更多
Anion adsorption behavior on Au colloid surface was investigated in virture of depositing monolayers of Au colloid on the self-assembled monolayers of cysteamine on a gold electrode. Po- tential-dependent anion adsor...Anion adsorption behavior on Au colloid surface was investigated in virture of depositing monolayers of Au colloid on the self-assembled monolayers of cysteamine on a gold electrode. Po- tential-dependent anion adsorption-desorption waves via the nonfaradaic current were obtained by means of cyclic voltammetry at Au coltoid-modified gold electrodes in the potential range of -2 00-600 mV. The adsorption sequence in the order of adsorption peak potentials (Epa) is OH- >citrate3 ->H2PO4- >Cl->SO42->ClO4->NO3-. Among them, citrate3- exhibited an en- tirely irreversible adsorption. A rise in temperature can increase the rates of adsorption-desorp- tion and improve the reversibility of the adsorption-desorption of Cl-, SO42-, ClO4-, NO3- and H2PO-4. The adsorption peak potentials shifted more negatively for Ca. 63 mV as the anion con- centrations were increased by a decade factor. The change of pH from 7 to 1 slightly affected the adsorption peak potentials of Cl- and NO3-. Au colloids with a smaller size (16 nm) gave rise to a better reversibility of the adsorption-desorption process and lower adsorption currents. The ex- perimental results of citrate ions adsorption on Au colloid surface show that Au colloids with a smaller size prepared by sodium citrate method exhibited a higher stability in the solution in com- parison to those with larger sizes because of its higher ratio of charge/mass. In other words, the smaller gold nanoparticles are covered with citrate ions monolayer that can also be formed at larg- er gold nanoparticles by means of electrochemical scan.展开更多
Gold nanoparticles have been increasingly used in catalysis, biomedical imaging, biological and chemical sensing, drug delivery, etc. In this study, a straightforward method that allows one to monitor the synthesis of...Gold nanoparticles have been increasingly used in catalysis, biomedical imaging, biological and chemical sensing, drug delivery, etc. In this study, a straightforward method that allows one to monitor the synthesis of gold sols and their aging, before their fine characterization by sophisticated techniques and before their use is described. Indeed, the “Colloid Thin-Layer Chromatography” method allows one to check the quality of gold colloidal sols during the synthesis. It is also well adapted for monitoring the aging of the sol before the visual observation of its degradation.展开更多
基金The authors acknowledge the financial support from the National Natural Science Foundation of China(No.42077335).
文摘Recently increasing concerns from the scientists and public have been paid for seawater pollution due to tetracycline(TC)overuse in maricultural area.However,there are few methods or instruments that can be used for specific and rapid detection of this antibiotic in seawater.In this study,the colloidal gold immunochromatographic assay(CG-ICA)was used to achieve this goal.A commercialized monoclonal antibody against TC(anti-TC mAb)was selected because of its higher sensitivity(half-maximal inhibitory concentration of 2.38μgL^(-1)).The prepared CG particles(average diameter of 20 nm)were used to label anti-TC mAb at pH 8.0.The conjugate pad was formed by spraying the CG-labeled anti-TC mAb on a glass fibre membrane followed by proper dryness.The test pad was made by immobilizing artificial antigen and anti-mouse mAb in the test line and the control line,respectively,in a nitrocellulose membrane.The test strip,assembled with sample pad,conjugate pad,test pad and absorbent pad,could be used to detect TC during seawater sample flowing through these components in turn.The results could be observed by the naked eye in 10min.The visible limit of detection(vLOD)was 20μgL^(-1) for TC in seawater.The CG-ICA test results were in good agreement with those of liquid chromatography-tandem mass spectrometry(LC-MS/MS).The assay also showed that,oxytetracycline(OTC)and chlortetracycline(CTC),as the structural analogues of TC,did not interfere with TC determination.Furthermore,the TC concentration given by test strip could not be affected by the fluctuation of temperature(10℃–30℃),pH(7–9)and salinity(0–40)of seawater.Therefore,CG-ICA is a suitable tool for rapid,on-site,and semi-quantitative detection of TC in seawater.
基金the National Natural Science Foundation of China (No.39970519)the Guangdong Province Natural Science Foundation (No.05001814,06012298)the Scientific Research Foundation for the Returned Overseas Chinese Scholars of State Education Ministry and Personnel Ministry,the Tackle Key Research Project of Guangxi Autonomous Region and Nanning City (No.0537007-7-2,200501065B)
文摘Methamidophos (Met) is a broad spectrum organophosphorus insecticide and acaricide.Even a trace of its residue is harmful to humans and many animals.In this study,the synthesis and identification of colloidal gold particles and antibody-colloidal gold conjugates were performed,and the preparation of colloidal gold immunochromatography strip was conducted for detection of Met residue.The size of colloidal gold particles was checked using a transmission electron microscope (TEM).The formation of antibody-coll...
文摘A method for the determination of human immunoglobulin G(IgG) based on a colloidal gold label by fluorospectrophotometry was developed. The sandwich immunoreaction among goat-anti-human IgG, human IgG and goat-anti-human IgG labeled with colloidal gold nanoparticles was applied in this experiment. First, a sandwich im- munocomplex was formed on the surface of 96 well clear polystyrene high bind stripwellTM microplate. After the formation of the sandwich immunocomplex, a solution was added to dissociate the immunocomplex at room temperature. Then the solution of each well was transferred into the corresponding test tube. Thirdly, the rhodamine B solution was injected into each test tube. The rhodamine B chloraurate was extracted into ether that was measured with a spectrofluorometer. The experimental results indicate that the fluorescence intensity increased with the increase of human IgG concentration. The fluorescence intensity of rhodamine B chloraurate at 570 nm was proportional to the logarithm of human IgG concentration in a range from 10 to 5 × 10^5 ng/mL. It was shown that the determination of human IgG was easily made with the proposed fluorospectrophotometry.
基金Financial supported by the Gansu ProvincialSci. & Tech. Department (1002NKDA037)
文摘A sandwich format immunochromatographic assay for detecting foot-and-mouth disease virus (FMDV) serotypes was developed. In this rapid test,affinity purified polyclonal antibodies from Guinea pigs which were immunized with sucking-mouse adapted FMD virus (A/AV88(L) strain) were conjugated to colloidal gold beads and used as the capture antibody,and affinity purified polyclonal antibodies from rabbits which were immunized with cell-culture adapted FMD virus (A/CHA/09 strain) were used as detector antibody. On the nitrocellulose membrane of the immunochromatographic strip,the capture antibody was laid on a sample pad,the detector antibody was printed at the test line(T) and goat anti-guinea pigs IgG antibodies were immobilized to the control line(C). The lower detection limit of the test for a FMDV 146S antigen is 11.7ng/ml as determined in serial tests after the strip device was assembled and the assay condition optimization. No cross reactions were found with FMDV serotype C,Swine vesicular disease (SVD),Vesicular stomatiti svirus (VSV) and vesicular exanthema of swine virus (VES) viral antigens with this rapid test. Clinically,the diagnostic sensitivity of this test for FMDV serotypes A was 88.7% which is as same as an indirect-sandwich ELISA. The specificity of this strip test was 98.2% and is comparable to the 98.7% obtained with indirect-sandwich ELISA. This rapid strip test is simple,easy and fast for clinical testing on field sites; no special instruments and skills are required,and the result can be obtained within 15 min. To our knowledge,this is the first rapid immunochromatogarpic assay for serotype A of FMDV.
基金the Guangdong Public Welfare Research and Capacity Building Project,China(2015A020209130)。
文摘Colloidal gold immunochromatographic assay(CGIA)is commonly used for the on-site detection ofβ-agonists that are sometimes used illegally as feed additives in swine diets.However,few studies have evaluated the causes of false-positive results that sometimes occur when applying CGIA in agricultural settings.In this study,we investigated if this false-positive phenomenon is related to the addition of certain traditional Chinese medicines(TCMs)to swine feed.We established and verified an extraction method for TCMs,and then applied CGIA to detectβ-agonists in the extracts of 105 TCMs and in the urine of swine dosed with TCMs,respectively.Liquid chromatography-tandem mass spectrometry was used to validate the results of the urine samples tested positive forβ-agonists using CGIA.The results were also verified using TCMs and colloidal gold test strips produced by different manufacturers.The extracts of Citri Reticulatae Pericarpium Viride,Citri Reticulatae Pericarpium,Magnoliae Officinalis Cortex,Chaenomelis Fructus,and Rhodiolae Crenulatae Radix Et Rhizoma were tested positive forβ-agonists.Meanwhile,the addition of Citri Reticulatae Pericarpium Viride and Citri Reticulatae Pericarpium to swine feed resulted in false-positive results forβ-agonists in swine urine.The results provide a new way to explain false-positive CGIA results and provide valuable information for livestock feeding programs.
基金Funded by the National Natural Science Foundation of China(No.40172017)
文摘The distribution of gold colloids in kaolinite and the interaction between gold and kaolinite surface were investigated by transmission electron mieroscotgy (TEM) and X-ray photoelectron spectroscopy ( XPS ). There is strong interaction between the gold particles and the edge surfaces of kaolinite, in low pH solution, the edge surface of kaolinite is positively charged and electrostutic attrcactive force between colloide gold panicles and the positive edge surface of kaolinite woald facilitate the adsorption of colloidal gold particles onto the suface. TEM observation shows that the aggregate morphology of gold particles was dominated by particle-particle interaction and gold particles were adsorbed on the edge surface of kaolinite crystals , resulting from the electrostatic attractive force between colloidal gold particles and the positice surfaces of kaolinite. XPS data show that in Au4 f electron spectra there are four energy peaks related to gold, 83.8 eV, 85.7 eV, 87.5 eV, and 89.4 eV, respectively, which suggests that in chemical states there are metallic gold and Au bonded to O, similar to the form of Au2O3 , and composite Au2O3 is formed between the edge surface of kaolinite and colloidal gold surface.
基金Supported by Beijing Training Project for the Leading Talents in S&T(Z171100001117158)
文摘A test strip was developed to rapidly detect fluoroquinolones in foods by colloidal gold immunochromatography method in combination with a food safety analyzer. The results showed that the test strip has the detection sensitivity of 20 μg/L for enrofloxacin, sarafloxacin, difloxacin, ofloxacin, norfloxacin, ciprofloxacin, pefloxacin, flumequine and danofloxacin, and the detection sensitivity of 40 μg/L for enoxacin and oxolinic acid. The test strip consumes only 10 min for detection, and the false positive rate and the false negative rate are both zero. The test strip can accurately, reliably and easily detect residual fluoroquinolones in foods, and is suitable for on-site detection of a large number of samples.
文摘Objective: p195, the major protein on the surface of Plasmodium falciparum merozoites, has been found to have ability to bind sialic acid residues on the surface of human erythrocytes, and this binding is thought to be a prerequisite for recognition of human erythrocyte by merozoite- This study attempted to map out the binding site of p195, thus providing a theoretical clue to developing an antimalaria vaccine which blockades invasion of merozoites into human erythrocytes. Methods: Eight proteins derived from pl95 were expressed in E. coli, and purified by Ni-chelate affinity chromatography. The re folded proteins were labelled with colloidal gold. The labelled protein complexes were co-incubated with human erythrocytes separately and simultaneously, and the proteins were put into the culture supernatant of P- falciParum to observe their effect on invasion of merozoites into erythrocytes. Results: A fragment of p195, M6 (amino acid sequence: 384 - 595), was found to have the ability to bind human erythrocytes. M6 gold complexes showed no ability to bind erythrocytes treated with trypsin or neuraminidase. M6 was also found to have the ability to inhibit invasion of merozoites of P. falciparym into human erythrocytes. Conclusiou: A fragment of p195, M6, has the ability to bind human erythrocytes. The binding is dependent on sialic acid residues, and may be a prerequisite to recognition of erythrocytes by merozoites.
文摘A comprehensive investigation on the formation mechanism of gold nanoparticles (AuNPs) in colloidal mixture obtained from the reduction of chloroauric acid (HAuCl4) solution using a single reducing agent (sodium citrate;process-I), (tannic acid;process-II), and a combination of two reducing agents (sodium citrate plus tannic acid;process-III) is reported. The growth steps at different time intervals during synthesis of colloidal AuNPs were monitored in situ and ex situ using various methods for all the three processes. The measurement of changes in the surface plasmon band position of colloidal AuNPs, along with dynamic light scattering results gave important information for the first assessing of particle size, shape and distribution. Besides, the size and morphological changes at different stages during different processes were also analyzed by transmission electron microscopy. The final Au particles of processes-I & II exhibited different shapes (spherical and nanowires) with particle size and nano wire diameter of 12 nm and 17 nm, respectively. Nevertheless, combination of two reductants (process-III) surprisingly leads to drastically reduced size (ca. 3 nm) with spherical morphology compared to their parent solutions with either of single reducing agent. This result clearly indicates that the combination of reductants has a significant influence on the particle size, morphology and formation mechanism.
基金This work was supported in part by the National Science Foundation of China(No.20504015)the Opening Research Fund from the State Key Laboratory of Polymer Chemistry and Physics,Chinese Academy of Sciences(No.200613).
文摘Narrow disperse poly(ethyleneglycol dimethacrylate-co-4-vinylpyridine) (poly(EGDMA-co-4-VPy)) microspheres were prepared by distillation-precipitation copolymerization of ethyleneglycol dimethacrylate (EGDMA) and 4-vinylpyridine (4-VPy) with 2,2'-azobisisobutyronitrile (AIBN) as initiator in neat acetonitrile. The polymer microspheres containing pyridyl group were then utilized as stabilizer for gold metallic colloids with the diameter around 7 nm, which were prepared by the in situ reduction of gold chloride trihydrate with sodium borohydride through the coordination of the pyridyl group on the gel layer and surface of the microsphere with the gold metallic nano-particles. The catalytic properties of the pyridyl- functionalized microsphere-stabilized gold metallic colloids and the behavior of the stabilized-catalyst for the recycling were investigated with reduction of 4-nitrophenol to 4-aminophenol as a model reaction.
基金the National Natural Sciences Foundation of China(No. 29835110).
文摘Anion adsorption behavior on Au colloid surface was investigated in virture of depositing monolayers of Au colloid on the self-assembled monolayers of cysteamine on a gold electrode. Po- tential-dependent anion adsorption-desorption waves via the nonfaradaic current were obtained by means of cyclic voltammetry at Au coltoid-modified gold electrodes in the potential range of -2 00-600 mV. The adsorption sequence in the order of adsorption peak potentials (Epa) is OH- >citrate3 ->H2PO4- >Cl->SO42->ClO4->NO3-. Among them, citrate3- exhibited an en- tirely irreversible adsorption. A rise in temperature can increase the rates of adsorption-desorp- tion and improve the reversibility of the adsorption-desorption of Cl-, SO42-, ClO4-, NO3- and H2PO-4. The adsorption peak potentials shifted more negatively for Ca. 63 mV as the anion con- centrations were increased by a decade factor. The change of pH from 7 to 1 slightly affected the adsorption peak potentials of Cl- and NO3-. Au colloids with a smaller size (16 nm) gave rise to a better reversibility of the adsorption-desorption process and lower adsorption currents. The ex- perimental results of citrate ions adsorption on Au colloid surface show that Au colloids with a smaller size prepared by sodium citrate method exhibited a higher stability in the solution in com- parison to those with larger sizes because of its higher ratio of charge/mass. In other words, the smaller gold nanoparticles are covered with citrate ions monolayer that can also be formed at larg- er gold nanoparticles by means of electrochemical scan.
文摘Gold nanoparticles have been increasingly used in catalysis, biomedical imaging, biological and chemical sensing, drug delivery, etc. In this study, a straightforward method that allows one to monitor the synthesis of gold sols and their aging, before their fine characterization by sophisticated techniques and before their use is described. Indeed, the “Colloid Thin-Layer Chromatography” method allows one to check the quality of gold colloidal sols during the synthesis. It is also well adapted for monitoring the aging of the sol before the visual observation of its degradation.