Colorimetric Sensors of Hg^2+ Ion Based on Functionalized Gold and Silver Nanoparticles

Monitoring the levels of toxic Hg^2+ metal ion in aquatic environment is important issue because this ion can have adverse effect in human health and environment. Therefore, detection of Hg^2+ ion in water is very important issue for improving human health and water quality. Metallic nanoparticles such as gold and silver nanoparticles (AuNPs AgNPs) have received much attention due to their colorimetric properties as well as localized surface plasmon resonance (LSPR) properties. AuNPs and AgNPs can easily change their colour (AuNPs: Red to Pink/Blue; AgNPs: Yellow to orange/red) which is easily discriminate by visual inspection. Functionalization of AuNPs and AgNPs offers an excellent application in many scientific worlds as the choice of ligands/functionalizing groups is outmost importance for their colloidal stability and function of the nanoparticles. In this review, we have discussed the colorimetric sensors of gold and silver nanoparticles based on functionalization of organic ligands, polymers, amino acid, and proteins for the detection of Hg^2+ ion in aqueous medium.