Plasmonics in bioanalysis: SPR, SERS, and nanozymes

In its complexity, light-matter interaction has a proven value for many scientific fields, such as quantum mechanics, material sciences and spectroscopy. In recent decades, bioanalytical tools have been developed, taking advantage of this knowledge. Sensing techniques such as the ones depending on (bio) catalytic reactions could be improved in terms of sensitivity and limits of detection and quantification with light stimuli. Others, such as surface plasmon resonance (SPR), could only thrive after the unraveling of some light-matter interaction particularities. In addition, the consolidation of nanoscience, including the capability to synthesize nanoparticles with enzyme-like activity and selectivity (nanozymes), led to a new perspective on the practical advantages of designed materials with optical attributes deriving from subwavelength-scaled particles. A set of techniques could benefit from this phenomenon. Examples are Surface-Enhanced Raman Spectroscopy (SERS), derived from the Raman effect, and Localized Surface Plasmon Resonance (LSPR), derived from SPR. This chapter is an overview of light-matter interaction from the perspective of bioanalytical tools, highlighting the state of the art of plasmonic-based electrochemical and electroanalytical methods, taking advantage of designed nanoparticles with controlled size, geometry and composition.