Hollow Prussian Blue nanocubes as peroxidase mimetic and enzyme carriers for colorimetric determination of ethanol.

The peroxidase-like activity of hollow Prussian Blue nanocubes (hPBNCs) is used, in combination with the enzyme alcohol oxidase (AOx), in a colorimetric ethanol assay. Different from other nanozymes, the large cavity structure of the hPBNCs provides a larger surface and more binding sites for AOx to be bound on their surface or in the pores. This extremely enhances the sensitivity of the assay system. In the presence of ethanol, AOx is capable of catalyzing the oxidation of alcohols to aldehydes, accompanied by the generation of hydrogen peroxide (HO). The hPBNCs act as peroxidase mimics and then can catalyze the oxidation of 3,3'5,5'-tetramethylbenzidine (TMB) by HO, resulting in a color change of the solution from colorless to blue with a strong absorption at 652 nm. The lower detection limit for ethanol is 1.41 μg∙mL. Due to the high catalytic activity of hPBNCs in weakly acidic and neutral solutions, the system was successfully applied to the determination of ethanol in mice blood. This is critically important for studying the alcohol consumption and monitoring the ethanol toxicokinetics. Graphical abstract Schematic representation of hollow Prussian Blue nanocubes (hPBNCs) used as both a peroxidase mimetic and as a carrier for alcohol oxidase. Utilizing hPBNCs along with the ethanol conversion enzyme, a sensitive colorimetric assay for ethanol was developed and applied to blood samples with satisfactory results.