My research focuses on the development and applications of plasmonic / fluorescence-based biosensors using noble metallic nanoparticles. In this regard, we have developed a new approach to glucose sensing based on the reversible aggregation of gold nanoparticles (due to specific dextran / Concanavalin A / glucose interactions) and their respective change in plasmon absorption (and scattering) upon glucose addition. This method proves to offer an across-the-board technology for glucose sensing in different physiological fluids due to its tunable glucose sensing range, where glucose can vary significantly from tears to blood, and its optical compatibility (absorbance above 600 nm).

We have also shown that a fluorescence-based detection scheme for small molecules can be realized using ligand-functionalized gold nanoparticles. The transduction scheme is based on the strong quenching of the fluorescence emission exerted by metallic surfaces on fluorophores positioned in their immediate vicinity (< 10 nm). In this regard, we have employed biotin (as a model small molecule) and its fluorophore-labeled antibody.

I am also interested in deposition and self-organization of the metallic nanostructures on surfaces for the applications in nanoscience and nanotechnology. One particular technology is Metal-Enhanced Fluorescence, where the fluorescence emission of flurophores in close proximity to silver nanostructures is enhanced due to coupling of oscillating surface plasmons with fluorophore's dipoles. In this regard, we have developed a new wet-chemical based methodology for the deposition of anisotropic silver nanostructures (nanorods and triangular nanoplates) on conventional glass substrates. These new surfaces are a significant improvement over silver island films for applications in metal-enhanced fluorescence, with routine 50-fold enhancement in emission intensity typically observed for protein-immobilized Indocyanine green.

We also reported the first findings of Metal-Enhanced Fluorescence (MEF) from modified plastic substrates. We have showed how plastic surfaces can be modified to obtain surface functionality, which in turn allows for silver deposition and therefore metal-enhanced fluorescence of fluorophores positioned above the silver using a protein spacer. Our findings show that plastic substrates are ideal surfaces for metal-enhanced phenomena, producing similar enhancements as compared to clean glass surfaces. We speculate that plastic substrates for MEF will find common place, as compared to the more expensive and less versatile traditional silica based supports.