A label-free visual immunoassay on solid support with silver nanoparticles as plasmon resonance scattering indicator |
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Authors: | Ling Jian Li Yuan Fang Huang Cheng Zhi |
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Affiliation: | College of Chemistry and Chemical Engineering and College of Pharmaceutical Sciences, MOE Key Laboratory on Luminescence and Real-Time Analysis, Southwest University, 400715 Chongqing, People’s Republic of China |
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Abstract: | By taking silver nanoparticles (Ag-NPs) as plasmon resonance scattering (PRS) indicator considering that Ag-NPs have strong plasmon resonance light scattering signals corresponding to their plasmon resonance absorption (PRA), we propose a label-free visual immunoassay on the solid support of glass slides. Our investigations showed that Ag-NPs could be adsorbed on the surface of glass slides where immunoreactions between a previously immobilized antigen and its antibody have occurred if the glass slides were immersed in an Ag-NP suspension whose pH value has been carefully adjusted. The optimal pH of the Ag-NP suspension depends on the nature of previously immobilized antigen and its antibody. It was found that the adsorption of negative-charged Ag-NPs on the surface of glass slides depends only on the content of antibody under optimal conditions. With a common spectrofluorometer to measure the PRS signals of the Ag-NPs adsorbed on the surface, we could detect antibody in the range of 10 to 160 ng ml−1. If a white light-emitting diode (LED) torch is employed to illuminate the glass slides, we can make visual detection of the antibody by the naked eye. |
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Keywords: | Immunoassay Silver nanoparticles Plasmon resonance scattering (PRS) |
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