High-Indexed Intermetallic PtSn Nanozymes with High Activity and Specificity for Sensitive Immunoassay.

Great efforts have been made to expand the application fields of nanozymes, which puts forward requirements for nanozymes with both superior catalytic activity and specificity. Herein, we reported the high-indexed intermetallic PtSn (H-PtSn) with high peroxidase-like activity and specificity. The resultant H-PtSn exhibits a specific activity of 345.3 U/mg, which is 1.82 times higher than Pt. Moreover, H-PtSn possesses negligible oxidase-like and catalase-like activities, achieving superior catalytic specificity toward HO activation. Experimental and theoretical calculations reveal both the splitting energy for adsorbed HO and the energy barrier for the rate-determining step of H-PtSn are significantly decreased compared with PtSn and Pt. Finally, a nanozyme-linked immunosorbent assay is successfully developed, achieving the sensitive and accurate colorimetric detection for carcinoembryonic antigen with a low detection limit of 0.49 pg/mL and showing practical feasibility in serum sample detection.