Plasmonic sensing through bioconjugation of Ag nanoparticles: Towards the development of immunoassays for ultralow quantification of antigens in colloidal dispersions

Abstract

The combination of the optical properties of silver nanoparticles with some of the tool-kits of the wide spread used ELISA method for antigen quantification immunoassays, give rise to an enzyme free, low cost, fast and more sensitive optical method denoted as Intensity Depletion Immuno-linked Assay (IDILA), that can be performed directly in colloidal dispersions without any immobilization of the capture antibody, antigen, secondary and primary antibodies on a substrate. The capabilities of the method for quantifying antigens at ultralow concentrations in colloidal dispersions as well as its performance are demonstrated for specific antigens of importance in medicine and in food science.