Regulating the enzymatic activities of metal-ATP nanoparticles by metal doping and their application for H2O2 detection

This paper reports a facile approach for fabricating metal–adenosine triphosphate (ATP) nanoparticles (NPs) by the self-assembly of ATP and metal ions under moderate conditions. Here, Cu-ATP NPs only showed laccase-like activity, but the Fe3+-doped Cu-ATP NPs could exhibit peroxidase-like activity, resulting in a decrease in laccase-like activity. Mn2+ ions functioned as a regulator to balance the enzyme-like activities of CuFe-ATP NPs, endowing the CuMnFe-ATP NPs with both strong laccase- and peroxidase-like activities. Surprisingly, the CuMnFe-ATP NPs also exhibited catalase-like activity under neutral conditions, improving the efficiency of phenol oxidation. X-ray photoelectron spectroscopy (XPS) analysis confirmed that the mixed valence states of the metals in the CuMnFe-ATP NPs accounted for the high catalytic efficiency; also, the large surface area and intrinsic porosity of the NPs were of great importance. The kinetic studies results indicated that the CuMnFe-ATP NPs exhibited rather strong affinities to 3,3,5′,5′-tetramethylbenzidine (TMB) and 2, 4-dichlorophenol (2,4-DP). On the basis of peroxidase-mimic activity, the CuMnFe-ATP NP system was employed to establish a facile colorimetric biosensing method for H2O2 determination, and the detection limit of H2O2 was 0.047 μmol⋅L−1. These results prove that the enzyme-like activities of Cu-ATP NPs can be modulated via simple metal doping, which may extend to other nanozymes.