Synthesis and characterization of peptide-conjugated silver nanoparticle for selective detection of Hg2+ in human blood plasma and tap water

Environmental pollution due to heavy metal ions is a serious health concern worldwide. In this study we have developed a new conjugate of cyclic peptide stylissatin A analogue with silver nanoparticle. The nanoparticles conjugated peptide was found highly selective sensor for Hg2+ in tap water and human blood. Cyclic peptide conjugate of silver nanoparticles (CP-AgNPs) were synthesized using chemical reduction method and characterized using UV–visible, FTIR, Zetasizer and atomic force microscopic techniques (AFM). CP-AgNPs were found to be highly stable in a wide range of pH and electrolyte concentration up to 1 M NaCl. The nanoparticles were spherical in shape and average sizes were found to be in the range of 60 to 80 nm. The photophysical potential of CP-AgNPs towards metal ions was examined using UV–visible spectroscopy. CP-AgNPs were found to be highly selective for Hg2+ ions as no interference was observed in the competitive experiments. The change in the absorption intensity of CP-AgNPs was directly proportional to the concentration of Hg+2 over a wide range of concentration (1–100 μM). Jobs plot experiment showed 1:2 binding stoichiometry between CP-AgNPs and Hg2+. Moreover CP-AgNPs were effectively used for the detection of Hg2+ in the laboratory tap water and blood plasma.