Etched PtCu nanowires as a peroxidase mimic for colorimetric determination of hydrogen peroxide

Etched PtCu nanowires (NWs) were synthesized by a hydrothermal reaction and chemical etching process. The NWs are shown to be viable peroxidase (POx) mimics capable of catalyzing the oxidation of the substrate 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H 2 O 2 to form a blue-green coloration. The mechanism of catalysis was investigated and the results demonstrated that H 2 O 2 is decomposed to form hydroxyl radicals which oxidize TMB in the presence of the NWs. Under optimized conditions, a steady-state kinetic analysis revealed that the NWs possess a stronger affinity for H 2 O 2 and TMB compared to the enzyme horseradish POx. Based on the high POx-like activity, a colorimetric assay for H 2 O 2 was established. Absorbance at 652 nm increases linearly in the 0.1–300 μM H 2 O 2 concentration range, and the detection limit is 0.06 μM (at S/N = 3). The assay was successfully applied to the determination of H 2 O 2 in (spiked) milk and contact lens solution. Furthermore, a highly sensitive test strip was designed which represents a low cost and fast alternative for the visual determination of H 2 O 2 . Schematic presentation of the colorimetric detection of H 2 O 2 . PtCu nanowires (PtCu NWs) can catalyze 3,3',5,5'-tetramethylbenzidine (TMB) oxidation by H 2 O 2 to produce blue-green oxidized 3,3',5,5'-tetramethylbenzidine (oxTMB). Based on the color change, test strips were designed for H 2 O 2 detection.