Plasmonic Fluorescence Enhancement in Diagnostics for Clinical Tests at Point-of-Care: A Review of Recent Technologies

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 fluorescent biosensors into the exploding field of point-of-care testing (POCT), which uses cost-effective strategies for rapid and affordable diagnostic testing. However, fluorescence-based assays often suffer from their feeble signal at low analyte concentrations, which often requires 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 fluorescent 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 article provides an overview of existing biosensors that employ various strategies for fluorescence enhancement via nanostructures and have demonstrated the potential for use as POCT. Biosensors using nanostructures such as planar substrates, freestanding 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.

Automated summary

Fluorescence-based biosensors are widely used in life sciences and biomedical applications due to their low detection limits and the ability to measure multiple biomarkers simultaneously. Recent research efforts have focused on implementing these biosensors in the field of point-of-care testing (POCT), which aims to provide rapid and affordable diagnostic testing. However, fluorescence-based assays often yield weak signals at low analyte concentrations, requiring complex and expensive instrumentation to maintain high detection sensitivity. Metal- and metal oxide-based nanostructures offer a solution to this problem by generating high field enhancements near their surfaces, which can improve the performance of fluorophores. This article provides an overview of existing biosensors that employ nanostructures to enhance fluorescence and have the potential for use in POCT.