HIGHLY SENSITIVE IMMUNOFLUORESCENCE ASSAY OF PROSTATE-SPECIFIC ANTIGEN USING SILVER NANOPARTICLES

Abstract

We consider the possibilities of applying the plasmon-enhanced fluorescence of monoclonal antibodies labeled with fluorescein isothiocyanate (FITC) to the prostate-specific antigen (PSA) for increasing the immunofluorescence analysis sensitivity. For the first time, for determining the PSA concentration we applied an immunochemical test system of two-center binding using a pair of non-competing monoclonal antibodies in combination with silver plasmon nanoparticles. The advantages over the standard PSA immunofluorescence assay are shown, namely: the intensity of the recorded fluorescent signal is increased by 2.3—3.2 times in the presence of silver nanoparticles in comparison with the signal of the test system on the intact surface of a polystyrene plate; the signal-to-noise ratio is increased by up to 2 times. In addition to the plasmon-enhanced fluorescence, the effect of an intermediate polyelectrolyte layer on the increasing of the sorption capacity of primary PSA antibodies is shown, which in turn influences the fluorescence signal intensity. A growth of the plasmon fluorescence enhancement factor with increasing the concentration of the labeled antibodies indicates the suppression of the self-quenching of the fluorescent labels by metal nanoparticles.