Rational design of monodispersed Au@Pt core–shell nanostructures with excellent peroxidase-mimicking activity for colorimetric detection of Cr(VI)

Cr(VI) is one of the most typical heavy metal contaminants and rapid detection of Cr(VI) is highly important in food control and public health. Herein, a core–shell Au@Pt nanozyme-based colorimetric assay was developed for the rapid and sensitive detection of Cr(VI). The monodispersed Au@Pt core–shell nanoparticles exhibited high peroxidase-mimicking activity and can catalyze colorless TMB into blue-colored oxidized oxTMB. After the addition of Cr(VI), the oxTMB molecules can be reduced into colorless TMB. The ultrathin Pt shell can prevent the Pt component from aggregation, thus improving the catalytic activity of Au@Pt nanozyme. These Au@Pt nanozyme-based Cr(VI) assays exhibited high sensitivity and selectivity and displayed satisfactory recoveries in practical samples. Our work highlights opportunities for the development of core–shell nanozymes with extensive applications in food safety, biomedicine, and environmental monitoring.