Metal‐Enhanced Fluorescence and Its Applications

Abstract The fluorescence‐enhancement phenomenon of fluorophores positioned near metal nanostructures (metal‐enhanced fluorescence, MEF) is the result of the interaction between the fluorophores and the localized surface plasmon resonance (LSPR) of the nanostructures. This enhancement phenomenon can contribute to the development of novel sensors based on unprecedented mechanisms, as well as improving the sensitivity of existing biosensors and imaging techniques. In this article, the two main mechanisms for MEF are briefly explained: the light‐harvesting nanoantenna effect and the increase in the radiative decay rate. This is followed by an introduction to metal nanostructures and nanoparticles (substrate‐based platforms and solution‐dispersed colloidal nanoparticle‐based platforms), which can act as MEF platforms. In addition, the efficient suppression of fluorescence blinking and photobleaching induced by the interaction with LSPR are described, as these are secondary advantages for fluorescence‐based sensors. Subsequently, the generation of hot spots, which could be one of the key phenomena for significant fluorescence enhancement, is outlined. An examination of usability of MEF platforms consisting of Al and Cu (metal species other than Au and Ag) to further improve their applicability is also discussed. Finally, some recent applications such as the development of imaging techniques, nanoprobes, and biosensors utilizing the MEF phenomenon are briefly introduced.