Colorimetric determination of cysteine by exploiting its inhibitory action on the peroxidase-like activity of Au@Pt core-shell nanohybrids

The authors report that the peroxidase-like activity of Au@Pt core-shell nanohybrids (Au@PtNHs) is selectively inhibited by cysteine. This finding has led to a highly sensitive colorimetric assay for cysteine that is based on the nanohybrid-catalyzed oxidation of TMB by H2O2 to form a blue product. The method has a detection limit of 5.0 nM and a linear range from 10 nM to 20 mu M. The assay is highly selective over other amino acids. It was successfully applied to the determination of cysteine in an injection containing a mixture of amino acids.