Direct detection of the interaction of tiny analytes with receptors using an advanced plasmonic biosensor

The interaction between tiny-molecular-weight analytes and receptors can be detected directly using advanced plasmonic biosensors. This paper proposes a plasmonic biosensor with Au nanoclusters embedded in a dielectric film. The sensor uses the attenuated total reflection (ATR) method to excite both the surface plasmons (SPs) and the particle plasmons (PPs). The local electro-magnetic (EM) field is enhanced by controlling the size and volume fraction of the embedded Au nanoparticles. The developed biosensor demonstrates a 10-fold improvement in resolution compared to a conventional surface plasmon resonance (SPR) biosensor. Using the proposed ultra-sensitive plasmonic biosensor, a direct detection approach is adopted to analyze the interactions of tiny molecules (< 200 Da) without the need for high molecular weight competitors or explicit labeling. The plasmonic biosensor developed in this paper provides a rapid diagnostic capability and has considerable potential for use in pharmaceutical research.