Iron Doped CuSn(OH)6 Microspheres as a Peroxidase-Mimicking Artificial Enzyme for H2O2 Colorimetric Detection

We designed and synthesized iron doped CuSn(OH) 6 (Fe/CuSn(OH) 6 ) microspheres, which was selected as a nanoenzyme to detect hydrogen peroxide (H 2 O 2 ), by a coprecipitation method for the first time. Significantly, Fe/CuSn(OH) 6 microspheres revealed the high peroxidase-like activity, which was evaluated using the peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) catalytically oxidized by H 2 O 2 . Colorless TMB could be turned into oxidized TMB (oxTMB) with a blue color change in the process of oxidation. The catalytic reaction mechanism has been proved to be • OH, attributing to H 2 O 2 decomposition. On the basis of the high peroxidase mimetic activity of Fe/CuSn(OH) 6 microspheres, a novel, simple, and sensitive H 2 O 2 colorimetric detection system was successfully constructed. Experimental data revealed that the Fe/CuSn(OH) 6 microspheres nanoenzyme additionally demonstrated the high peroxidase-like activity compared with horseradish peroxidase. Furthermore, based on the Fe/CuSn(OH) 6, a rapid detection of H 2 O 2 could be come true in the wide range (30–1000 μM) with a lower detection limit of 9.49 μM (S/N = 3). The feasibility of this convenient method was confirmed by qualitative detection of H 2 O 2 residue in milk.