Mineralizing gold-silver bimetals into hemin-melamine matrix: A nanocomposite nanozyme for visual colorimetric analysis of H2O2 and glucose.

A nanocomposite nanozyme has been fabricated through mineralizing gold-silver bimetals into Hemin (Hem)-coupled melamine (MA) polymer matrix for visual colorimetric analysis of H2O2 and glucose. Catalytic Hem was cross-linked onto MA scaffold for the mineralization of Au-Ag bimetals yielding the rod-like nanocomposite of MA-Hem/Au-Ag. It was discovered that the resulting nanocomposite could present high aqueous stability and especially improved catalysis, which was more than four-fold higher than that of native Hem. Catalytic kinetics studies indicate that the prepared nanocomposite nanozyme could present much higher affinities to the substrates than those of native Hem or even horseradish peroxidase. Herein, the so mineralized Au-Ag bimetals with the "silver effect" would act as "nanowires" for promoting the electron transferring of nanocomposite nanozyme. Moreover, the Hem-coupled MA polymer matrix with high specific surface area could ensure the high adsorption capacity for the reactant substrates and targeting analytes. The application feasibility of the developed nanocomposite nanozyme was demonstrated subsequently by the colorimetric assays for H2O2 and glucose separately in milk and blood samples, with the linear ranges of 0.010-2.50 mM and 0.0050-2.0 mM, respectively. Such a bimetal mineralization-based fabrication route may open a new door toward the design of diverse nanocomposites nanozymes with improved catalysis and adsorption performances.