Abstract

Plasmonic Amplification for Fluorescence Biosensors

Jakub Dostalek, Researcher, Austrian Institute of Technology

Fluorescence represents (arguably) mostly used optical method for detection of chemical and biological species in important fields of medical diagnostics and food safety. The sensitivity of fluorescence analytical tools can be advanced through the coupling of fluorophore labels with plasmonic nanostructures. This approach is referred as plasmon-enhanced fluorescence (PEF) and it takes advantage of strong confinement of light upon the resonant excitation of surface plasmons - optical waves originating from collective oscillations of free electron density and associated electromagnetic field at surfaces of metallic films and nanoparticles. Enhancement factors up to 103 can be achieved through the combination of surface plasmon-mediated excitation rate, improved quantum yield, and enhanced collecting efficiency of light emitted by fluorophore labels. The presentation will discuss tailoring of PEF for detection of analytes with different size (medium size protein and large bacterial pathogen) by control of probing field profile and density of plasmonic hotspots. In addition, our efforts on implementation of PEF either to existing analytical instruments or to new compact portable devices will be presented. The performance of PEF will be illustrated by several assays for detection of molecular analytes at low-femtomolar concentrations and harmful bacterial pathogens at concentrations as low as 10 cfu/mL.