Enhancement of surface plasmon resonance using colloidal gold nanoparticles embedded in a silica layer

This paper presents a strategy for the signal enhancement of surface plasmon resonance biosensors using colloidal gold nanoparticles and a silica layer. We describe the method for the deposition of a silica-stabilized gold nanoparticle layer on a gold film, namely an enhanced surface plasmon resonance chip. This chip shows significant changes in its surface plasmon resonance signals when biomolecules are attached to its surface as compared to a normal gold surface. These characteristics are closely related to the surface plasmon resonance effect as determined using prostate-specific antigen. The detection limit of the enhanced surface plasmon resonance chip is determined to be 0.01 ng/mL for a prostate-specific antigen immunoassay. The use of an enhanced surface plasmon resonance chip makes it possible to enhance signals 1000-fold compared to the signals obtained by conventional surface plasmon resonance sensing. The enhancement of the surface plasmon resonance spectral shift results from the coupling of the surface and particle plasmons through the application of a silica-stabilized gold nanoparticle layer on the gold surface.