Role of Glutathione Capping on Copper Nanoclusters and Nanoparticles: A Review

Being a highly available 3d group11 transition metal, copper in the form of nanoparticles (NPs) and nanoclusters (NCs) has been extensively investigated. However, aerial oxidation limits its application. Capping agents and experimental conditions have quite a significance in the stability of copper particles. Here, we reviewed the glutathione (GSH) capping on copper nanopaticles (CuNPs) and copper nanoclusters (CuNCs). CuNCs and CuNPs benefit greatly from the stabilizing, modifying, and enhancing effects of GSH, a naturally occurring tripeptide. It assists in preventing their aggregation, which is a typical problem for these tiny particles. Strong metal-sulfur (Cu-S) interactions allow the thiol (-SH) groups in GSH molecules to attach to the copper surface, forming a protective coating that prevents copper particles from clumping together. The synthesis with the mechanism, and the fate of copper particles, with myriad applications such as bioimaging, antibacterial activity, and sensing (antibiotics, heavy metals, pH, and other biomolecules) were reviewed here. Such particles were satisfactorily biocompatible. Moreover, the effect of components was also summarized justifying that tripeptide GSH was much superior to individual components in the context of applications, although cysteine was considered to be a pivotal component. The effect of adulteration of other metals in copper particles often enhances their utility. This review will open a new window for thiolated capping to young researchers, venturing into the field of material science. Graphical Abstract