Arsenate reductase from Thermus thermophilus conjugated to polyethylene glycol-stabilized gold nanospheres allow trace sensing and speciation of arsenic ions

Abstract

Water sources pollution by arsenic ions is a serious environmental problem all around the world. Arsenate reductase enzyme ( TtArsC ) from Thermus thermophilus extremophile bacterium, naturally binds arsenic ions, As(V) and As (III), in aqueous solutions. In this research, TtArsC enzyme adsorption onto hybrid polyethylene glycol-stabilized gold nanoparticles (AuNPs) was studied at different pH values as an innovative nanobiosystem for metal concentration monitoring. Characterizations were performed by UV/Vis and circular dichroism spectroscopies, TEM images and in terms of surface charge changes. The molecular interaction between arsenic ions and the TtArsC -AuNPs nanobiosystem was also monitored at all pH values considered by UV/Vis spectroscopy. Tests performed revealed high sensitivities and limits of detection equal to 10 ± 3 M −12 and 7.7 ± 0.3 M −12 for As(III) and As(V), respectively.