Surface Plasmon Resonance Biomolecular Recognition Nanosystem: Influence of the Interfacial Electrical Potential

It is shown that the response of a surface plasmon resonance nanosystem designed according to Kretschmann geometry on the application of an external electric potential to the gold-electrolyte interface is well described by the proposed mathematical model, which takes into account the geometric surface imperfection and dependence of optical constants of the surface layer of gold film and capacitance of the electrical double layer on applied voltage. This model allows the appropriate correction for results of electrochemical surface plasmon resonance measurements. The dependence of a value of biomolecules adsorption in a surface plasmon resonance nanosystem on applied electric potential is shown for the first time. It is found that a shift of surface plasmon resonance angular position (Δθ(SPR)) and a change of capacitance of electrical double layer on the surface of gold (ΔC(dl)) for the adsorption of proteins under applied voltage are related to the nonlinear dependence Δθ(SPR) = (a + b x ΔC(dl))(-1). This phenomenon can be exploited in biochemical analysis to monitor the interaction of biomolecules, enhance response of biosensors, block unwanted adsorption, etc.