title: A label-free visual immunoassay on solid support with silver nanoparticles as plasmon resonance scattering indicator.
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.
authors.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.
authors.forename: Jian
authors.initials: J
authors.lastname: Ling
authors.forename: Yuan Fang
authors.initials: YF
authors.lastname: Li
authors.forename: Cheng Zhi
authors.initials: CZ
authors.lastname: Huang
mesh_terms: D000327:Adsorption; D000818:Animals; D000906:Antibodies / Q000032:analysis / Q000276:immunology; D000937:Antigen-Antibody Reactions; D002417:Cattle; D005898:Glass; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation / Q000379:methods*; D007202:Indicators and Reagents; D053768:Metal Nanoparticles; D012834:Silver; D013194:Staining and Labeling
chemical_list: D000906:Antibodies; D007202:Indicators and Reagents; D012834:Silver