Rock salt type NiO assembled on ordered mesoporous carbon as peroxidase mimetic for colorimetric assay of gallic acid

Mimetic enzymes are of scientific and practical significance as alternatives for natural enzymes because the latter ones have drawbacks such as instability and high cost. Here we report that ordered mesoporous carbon supported rock salt type NiO nanocomposite (NiO-OMC) exhibited interesting peroxidase-like activity in the typical reaction of H2O2 and 3,3',5,5'-tetramethylbenzidine. Further, based on gallic acid (GA) quenching the catalytic activity of NiO-OMC nanocomposite, selective colorimetric detection of GA was developed. The decreased absorbance @650 nm in the presence of GA is linear with GA concentration within 0.2-10 mu M. The limit of detection is 0.112 mu M GA. The proposed method is applicable to real samples measurements.