A sensitive hydrogen peroxide biosensor using ultra-small CuInS2 nanocrystals as peroxidase mimics

In this paper, CuInS 2 nanocrystals are prepared by microwave-assisted method and found to possess intrinsic peroxidase-like activity for the first time. It could catalytically oxidize 3,3′,5,5′-tetramethylbenzidine by H 2 O 2 to produce a color changing reaction, which is the principle for sensing of H 2 O 2 level. Furthermore, the catalysis mechanism was studied. It was found to follow Michaelis–Menten kinetics and peroxidase activity varied with respect to electrostatic affinity between nanoparticles and substrates, evidenced by differences in determined kinetic parameters. In regard to this, a biosensor was developed for the detection of H 2 O 2 . The results indicated that a good linear relationship was obtained from 0.1 to 20   μM of H 2 O 2 . The detection limit is calculated to be 0.03   μM, which is better than previous reports utilizing various methods. Taking into account the advantages of ultra-small size, good stability, and high biocompatibility, CuInS 2 nanocrystals are expected to have potential applications in biotechnology and clinical diagnosis as enzymatic mimics.