Guided Immobilization of Quantum Dots on Gold Nanogratings for Enhanced Surface Plasmon Resonance Biosensing

I. Introduction The literature points to a vast array of plasmonic enhancement effects being studied for biosensing applications. Plasmonic biosensors utilise surface plasmon waves to sense the surface adsorption of analytes from a complex sample solution. In this report, we present a surface plasmon resonance (SPR) biosensor (based on the Kretchmann configuration) which incorporates surface nanogratings and guided quantum dot immobilization. The adsorption of fluorophores on plasmonic surfaces is interesting due to two known physical effects associated with the interaction between the fluorophore and the electromagnetic field. The propagating surface plasmon wave generates, along the nanograting structures, high electromagnetic (EM) field intensities that can excite the adsorbed fluorophores to produce a highly directional and polarized emission [1]. Moreover, the presence of fluorophores causes an important change in both the real and imaginary parts of refractive index near the plasmonic surface affecting the excitation and propagation of the plasmon wave [2]. Therefore, there is significant scope in exploring these EM interactions as amplification methods for enhanced SPR [3].