Gallotannin mediated silver colloidal nanoparticles as multifunctional nano platform: Rapid colorimetric and turn-on fluorescent sensor for Hg2+, catalytic and In vitro anticancer activities

Abstract

A simple approach has been developed to prepare gallotannin (GT) mediated silver nanoparticles (AgNPs) for detection of Hg2+ ion in aqueous solution. The synthesized silver nanoparticles was characterized by different techniques such as UV–vis spectrophotometry, XRD, scanning electron microscopy, and EDX. Amongst the all metal ion tested, only Hg2+ shows selective colorimetric and fluorimetric change to GT capped AgNPs. A quick naked eye color change of GT capped AgNPs from yellowish-brown to colorless shows high sensitivity of present method. With addition of Hg2+ ion, the fluorescence enhancement was observed for GT capped AgNPs. The mechanism for the change in color and fluorescence enhancement of nanoparticles with addition of incremental amount of Hg2+ is due to the change in polarization near metal surface region and internal charge transfer phenomenon. The linear range for the detection of Hg2+ was found to be 0.1–1 nM with lower detection limit (LOD) 0.037 nM. The present approach has been successfully utilized to quantitative determination of Hg2+ from environmental samples. The another advantages of prepared silver nanoparticles (GT-AgNPs) is that it shows significant photocatalytic activity for organic transformation and anticancer potential against cancer cell line MDA-MB-231 and A375 with an LD50 of 111.5 µg/mL and 185 µg/mL, respectively.