The interaction between gold nanoparticles and proteins such as bovine serum albumin and immunoglobulin G under the condition of different pH values was studied based on the measurement of zeta potential and fluoresce...The interaction between gold nanoparticles and proteins such as bovine serum albumin and immunoglobulin G under the condition of different pH values was studied based on the measurement of zeta potential and fluorescence quenching of the proteins before and after proteins were bound with gold nanoparticles. Aggregations were found in gold colloid aqueous solution after addition of proteins by TEM characterization and UV-Vis spectroscopy deterruination. The results showed that the values of zeta potential were quite different, the binding constant Kb and stoichiometry n were slightly increased with the increase of pH value. In conclusion, two factors could affect markedly the interaction between gold nanoparticles and proteins, that is, surface charge and the coordination effect between gold nanoparticles and indole group of the tryptophan residue of proteins.展开更多
We report an ultrasensitive protocol for electrochemical sensing using the hydroxyl-rich C-dots assisted synthesis of gold nanoparticles(C-dots@AuNP) as labels with copper depositon reaction. The C-dots catalyzing cop...We report an ultrasensitive protocol for electrochemical sensing using the hydroxyl-rich C-dots assisted synthesis of gold nanoparticles(C-dots@AuNP) as labels with copper depositon reaction. The C-dots catalyzing copper deposition reaction was implemented for the first time. We constructed a sandwich-type immunosensor on the chitosan modified glassy carbon electrode(GCE) by glutaraldehyde(GA) crosslinking, with C-dots@AuNP as biolabels. Copper was deposited on the catalytic surfaces of second antibody-conjugated C-dots@AuNP nanoparticles through CuSO_4-ascorbic acid reduction, because both C-dots and AuNPs could strongly catalyze the CuSO_4 and ascorbic acid to form Cu particles, which amplified the detection signal. Then the corresponding antigen was quantified based on simultaneous chemical-dissolution/cathodic-preconcentration of copper for insitu analysis using anodic stripping square wave voltammetry(ASSWV) directly on the modified electrode. Under optimized conditions, these electrodes were employed for sandwich-type immunoanaly sis, pushing the lower limits of detection(LODs)down to the fg mL^(-1) level for human immunoglobulin G(IgG) and cardiac troponin I(cTnI), a cardiac biomarker. These novel sensors have good stability and acceptable accuracy and reproducibility, suggesting potential applications in clinical diagnostics.展开更多
Based on MEMS technology,immunosensor with an'Au,Pt,Pt'three-microelectrode system enclosed in a SU-8 micro pool was fabricated.Employing SAMs technique,the Au electrode was modified by cysteamine(Cys)to assem...Based on MEMS technology,immunosensor with an'Au,Pt,Pt'three-microelectrode system enclosed in a SU-8 micro pool was fabricated.Employing SAMs technique,the Au electrode was modified by cysteamine(Cys)to assemble gold nanopanicles(nanogold)layer,subsequently,a layer of protein G(PG)was immobilized on nanogold layer to further capture antibody orientedly.Compared with the immunosensors using bulky gold electrode and direct PG binding to electrode immobilization technique for antibody,it has attractive advantages,such as miniaturization,good compatibility,broad linear range for human immunoglobulin(HIgG)and easy to be designed into array.展开更多
基金Project supported by the National Natural Science Foundation of China （No. 30471599） and Development Foundation of Shanghai Science and Technology （No.03ZR14057）.
文摘The interaction between gold nanoparticles and proteins such as bovine serum albumin and immunoglobulin G under the condition of different pH values was studied based on the measurement of zeta potential and fluorescence quenching of the proteins before and after proteins were bound with gold nanoparticles. Aggregations were found in gold colloid aqueous solution after addition of proteins by TEM characterization and UV-Vis spectroscopy deterruination. The results showed that the values of zeta potential were quite different, the binding constant Kb and stoichiometry n were slightly increased with the increase of pH value. In conclusion, two factors could affect markedly the interaction between gold nanoparticles and proteins, that is, surface charge and the coordination effect between gold nanoparticles and indole group of the tryptophan residue of proteins.
基金supported by the National Key Research and Development Program of China(2016YFA0201300)the National Natural Science Foundation of China(21335001,21575006)China Postdoctoral Science Foundation(2016M600846)
文摘We report an ultrasensitive protocol for electrochemical sensing using the hydroxyl-rich C-dots assisted synthesis of gold nanoparticles(C-dots@AuNP) as labels with copper depositon reaction. The C-dots catalyzing copper deposition reaction was implemented for the first time. We constructed a sandwich-type immunosensor on the chitosan modified glassy carbon electrode(GCE) by glutaraldehyde(GA) crosslinking, with C-dots@AuNP as biolabels. Copper was deposited on the catalytic surfaces of second antibody-conjugated C-dots@AuNP nanoparticles through CuSO_4-ascorbic acid reduction, because both C-dots and AuNPs could strongly catalyze the CuSO_4 and ascorbic acid to form Cu particles, which amplified the detection signal. Then the corresponding antigen was quantified based on simultaneous chemical-dissolution/cathodic-preconcentration of copper for insitu analysis using anodic stripping square wave voltammetry(ASSWV) directly on the modified electrode. Under optimized conditions, these electrodes were employed for sandwich-type immunoanaly sis, pushing the lower limits of detection(LODs)down to the fg mL^(-1) level for human immunoglobulin G(IgG) and cardiac troponin I(cTnI), a cardiac biomarker. These novel sensors have good stability and acceptable accuracy and reproducibility, suggesting potential applications in clinical diagnostics.
基金This work is supported by the National Natural Science Foundation of China （Grant No. 90307014）.
文摘Based on MEMS technology,immunosensor with an'Au,Pt,Pt'three-microelectrode system enclosed in a SU-8 micro pool was fabricated.Employing SAMs technique,the Au electrode was modified by cysteamine(Cys)to assemble gold nanopanicles(nanogold)layer,subsequently,a layer of protein G(PG)was immobilized on nanogold layer to further capture antibody orientedly.Compared with the immunosensors using bulky gold electrode and direct PG binding to electrode immobilization technique for antibody,it has attractive advantages,such as miniaturization,good compatibility,broad linear range for human immunoglobulin(HIgG)and easy to be designed into array.
