Synthesis and stability analysis of papain‐functionalized gold nanoparticles (P‐AuNPs) for the colorimetric detection of mercury in milk

Abstract

To detect mercury in dairy cow milk by colorimetric techniques, papain‐functionalized gold nanoparticles (P‐AuNPs) were synthesised. Papain‐functionalized gold nanoparticles aggregated when mercury ions were introduced, causing their absorption peak to shift from 525 to 575 nm. Dynamic light scattering and transmission electron microscopy determined that aggregated P‐AuNPs average sizes were 26.60 nm and 15.17–18.23 nm, respectively, with monodispersed. The detection limit of P‐AuNPs for mercury in milk samples was 1.0 ppm with high recovery. This sensor showed relatively high selectivity and sensitivity towards Hg2+ ions in milk. This method shows utility in developing countries for monitoring the concentration of Hg2+ in water, milk and food items for safety purposes.