A novel optical immunosensing system based on measuring surface enhanced light scattering signals of solid supports

Abstract

An optical immunosensor based on measuring the surface enhanced light scattering (SELS) signals is developed by simultaneously scanning the excitation and the emission monochromators of a common spectrofluorometer. The formation of silanization on solid surface of glass slides and the binding of antibody with antigen in series have been confirmed by measuring the SELS signals. When 100 μg ml −1 goat anti-human IgG, goat anti-rabbit IgG and rabbit anti-human IgG are immobilized on the solid surface, human IgG and rabbit IgG in the range of 0.1–100 μg ml −1 and human IgG in the range of 0.1–10 μg ml −1 could be detected, and the lowest detectable concentration could, respectively, reach 10, 50 and 10 ng ml −1. This label-free assay is more rapid and simpler than those conventional immunoassay methods. Under optimal experimental conditions, the sensor based on SELS has a high specificity with corresponding antigen (Ag), and other co-existing proteins in solution, for example, such as bovine serum albumin (BSA) and human serum albumin (HSA) do not show interference effect. Regenerated simply by rinsing in carbamide solution, the sensor could achieve three assay cycles without great loss of sensitivity.