LAUSR

Fluorescence-based biosensors have widely been used in the life-sciences and biomedical applications due to their low limit of detection and a diverse selection of fluorophores that enable simultaneous measurements of multiple biomarkers. Recent research effort has been made to implement fluorescence-based biosensors into the exploding field of point-of-care testing (POCT), which uses cost-effective strategies for rapid and affordable diagnostic testing. However, challenges remain to transition fluorescence-based sensors towards POCT due to their feeble signal at low concentrations of the analyte, which often require sophisticated, costly, and bulky instrumentation to maintain high detection sensitivity. Metal- and metal oxide-based nanostructures offer a simple solution to increase the output signal from fluorescence-based biosensors due to the generation of high field enhancements close to a metal or metal oxide surface, which has been shown to improve the excitation rate, quantum yield, photostability, and radiation pattern of fluorophores. This review provides an overview of existing biosensors that employ various strategies for fluorescence enhancement via nanostructures and have demonstrated the potential for sensitive and rapid diagnostic testing. Biosensors using nanostructures such as planar substrates, free-standing nanoparticles, and metal-dielectric-metal nanocavities are discussed with an emphasis placed on technologies that have shown promise towards POCT applications without the need for centralized laboratories. This article is protected by copyright. All rights reserved.