Development of multifunctional Cu sensitized Ag-dextran nanocomposite for selective and sensitive detection of mercury from environmental sample and evaluation of its photocatalytic and anti-microbial applications

Mercury has been considered as the most toxic metal pollutants that pose lethal threat to environment and the human health at small concentrations. Thus, the development of a rapid, inexpensive and simple technique for Hg2+ ion detection in real aqueous samples is paramount. The present study reported a colorimetric assay for sensing Hg2+ ion using Cu sensitized Ag-dextran nanocomposite (NCs) in presence of tyrosine. The particle was characterized by UV–visible (vis) spectrophotometer, zeta sizer, HR-TEM, particle size analyzer, FT-IR, EDAX and XRD. The NCs possessed a hydrodynamic diameter of 26 ± 1.4 nm and − 32.21 ± 3 mV was the zetapotential value. The colour of Ag/Cu NCs was brownish yellow due to the LSPR band centred at 408 nm. An appreciable colour change was observed from yellowish brown to colourless after interaction with Hg2+ ion. A good linearity existed in the correlation curve between the absorbance value (ℷ = 408 nm) and the Hg2+ ion concentrations (20 nM – 100 nM). A simple, low cost paper-strip based sensor of Ag/Cu NCs used as an real time portable Hg2+ detection. The influence of other metal ions, pH (5.0 to 9.0), salinity (0.1–0.8%) and temperature (15–50 °C) for the Hg2+ detection was also investigated. The NCs exhibits high specificity, sensitivity and stability towards the Hg2+ detection at low nano molar level. Additionally, the NCs exhibited excellent MB degradation under irradiation of visible light and it also showed antimicrobial activity against B. subtilis and E. coli. The study demonstrated the application of Cu sensitized Ag-dextran NCs in detection, photocatalysis, and as an antimicrobial agent.