Plasmonic Nanoparticle-based Protein Detection by Optical Shift of a   Resonant Microcavity
  We demonstrated a biosensing approach which, for the first time, combines the high-sensitivity of whispering gallery modes (WGM) with a metallic nanoparticle based assay. We provided a computational model based on generalized Mie theory to explain the higher sensitivity of protein detection through Plasmonic enhancement. We quantitatively analyzed the binding of a model protein (i.e., BSA) to gold nanoparticles from high-Q WGM resonance frequency shifts, and fit the results to an adsorption isotherm, which agrees with the theoretical predictions of a two-component adsorption model. 
Miguel A. Santiago-Cordoba, Svetlana V. Boriskina, Frank Vollmer,   Melik C. Demirel
physics.optics physics.ins-det