Metal Nanoclusters in Point-of-Care Sensing and Biosensing Applications

Nanoclusters are nanostructures consisting of few to tens of atoms which have attracted great interest from the scientific community due to their applications in a myriad of fields, from catalysis to biomedical applications. Due to the discrete energy levels resulting from their ultrasmall size, nanoclusters exhibit distinctly different chemical, optical, and electrical properties compared with their larger nanoparticle counterparts. Unlike previously reported nanostructures with larger dimensions (1-10 nm), which typically have a single advantage (for example, high conductivity or optical properties), nanoclusters can be used as signaling and/or reaction-accelerating materials in almost all sensing assays with enhanced properties. Nanoclusters are among the most promising luminescent emitters (electrochemiluminescent, fluorescent, chemiluminescent, and colorimetry) with high quantum yield and better biocompatibility than conventional emitters. Considering their excelent biocompatibility, tailored modification, and desirable electrochemical and optical tunability, nanoclusters have opened new horizons in designing high-performance sensing and biosensing devices. In addition, they represent excellent electrochemical and photoelectrochemical behaviors with improved functionality and environmentally friendly properties compared to traditional compounds. This review discusses the recent advances in nanoclusters, their applications in sensing and biosensing, current limitations, and prospects to overcome these challenges. The present study gives a much brighter vision of nanoclusters that discusses one by one their particular advantages and role in developing sensing frameworks.