Enhanced peroxidase-like activity of CuO/Pt nanoflowers for colorimetric and ultrasensitive Hg2+ detection in water sample

A general method for the preparation of Pt doped CuO/Pt nanoflowers (CuO/Pt NFs) for peroxidase mimicking has been demonstrated via hydrothermal method. Pt ions could be reduced to Pt nanoparticles by using the ascorbic acid (AA) as reducing agent and Pt ions were uniformly doped in the CuO nanoflowers by using the bovine serum albumin (BSA) as the stabilizer. The obtained CuO/Pt NFs exhibited a higher peroxidase-like catalytic activity than individual CuO and Pt nanoparticles alone, which could be ascribed to their synergistic effect. In the presence of hydrogen peroxide (H2O2), the CuO/Pt NFs could catalyze the oxidation of chromogen 3,3′,5,5′-tetramethylbenzidine (TMB) to a blue color product. The peroxidase activity of CuO/Pt NFs was selectively inhibited by Hg2+ due to form the CuO/Pt-Hg trimetallic amalgam. However, the inhibition was not affected by other metal ions. Therefore, a novel colorimetric biosensor was developed for sensitive detection of mercuric ions by using CuO/Pt NFs. This method exhibited a wide response linear range, low limit of quantification values, excellent sensitivity and selectivity for detection of Hg2+ in various ground water samples, which was verified with CVAAS. With the advantages of rapid response, simple operation, naked-eye observation and low cost, the colorimetric CuO/Pt NFs sensor showed bright prospects for detection of Hg2+ in various water samples and public drinking water distribution systems.