Colorimetric sensing approaches based on silver nanoparticles aggregation for determination of toxic metal ions in water sample: a review

This review summarises the progress that has been made in silver nanoparticles (NPs) based colorimetric quantification of toxic metal ions in the water and environmental samples. Due to the anthropogenic activities, contamination of metallic ions in the ecosystem rapidly increased, inflicting serious illness to human and aquatic life. Consequently, to monitor the presence of metallic ions in the environment and waterbodies a simple and rapid assay is urgently needed. Recently, silver NPs based colorimetric assay has received tremendous interest in simple and fast determination of toxic metal ions. Localised surface plasmon resonance (LSPR) is a vital optical property of silver NPs exhibiting different colours in the visible vicinity of the electromagnetic spectrum depending on their shape, size and aggregation conditions. LSPR provides an excellent platform for the development of an ingenious, economical, visual readout assay for on-site monitoring of various analytes. Here in this study, we critically summarised the recent progress that has been made in the silver NPs based colorimetric assay for recognition of toxic metal ions. Also, the mechanism and future applications of each method were discussed.