ABSTRACT
Optical sensing, based on color or fluorescence, has been the most established and also preferred method for several decades, mainly due to the outcomes that can be appreciated either by the naked eye directly or through optical microscopy. This chapter briefly introduces the Localized Surface Plasmon Resonance (LSPR) phenomenon of the plasmonic gold and silver nanoparticles, followed by its exploitation in realizing various sensing strategies including label-free and labeled biosensors. The LSPR phenomenon found in the noble-metal nanostructures imparts excellent optical properties in the visible and near-infrared regions of the electromagnetic spectrum, thereby making them an invaluable candidate for several colorimetric and fluorometric sensing applications. Label-free aggregation-based biosensors have become increasingly popular in recent years, due to their ease of use, visible color change, and cost-effectiveness.
