DNA-Encoded Bimetallic PtAg Nanocluster-zyme with Programmable POD-mimicking Activity for Accurate Trimodal Biosensing and Cascade Logic Circuit-Empowered Target Recognition

Exploring novel-type nanozymes with programmatically manipulated enzyme-mimicking activity for targets' accurate identification and multimodal biosensing represents one of the most fascinating yet challenging research frontiers. Herein, taking DNAs as programmable biotemplates, we prepared bimetallic PtAg nanocluster-zyme via simple in situ reduction. Among them, the A20-templated PtAg nanozyme exhibited superior peroxidase-like (POD-like) activity, as confirmed by optical analyses, steady-state kinetics, and electron paramagnetic resonance spectroscopy, with •O₂^- and •OH identified as the primary reactive oxygen species. Taking Pt-AMP with the Pt-N₄ coordination structure as representative, pluralistic DFT calculations were performed. Corresponding results manifested the superior affinity of nanozyme for H₂O₂ and TMB, the elongated O-O bond length of H₂O₂ and facilitated electron-transfer ability at the catalytic core. Subsequently, by harnessing the efficient catalytic oxidation of TMB and AR, we fabricated a colorimetric-photothermal-fluorescent trimodal sensing platform for assessing total antioxidant capacity and alkaline phosphatase activity. Superior to previous single/dual-modal biosensors, this work demonstrated significant advantages in sensitivity, reliability, and accuracy, and showed acceptable adaptability in diversified real matrices (human serum, tablets, and beverages). Furthermore, we fabricated target-responsive cascade logic circuits by virtue of the proper incorporation of trimodal signals and Boolean logic, and achieved the smart recognition of targets. This work not only provided a mild, simple, and efficient biotemplated approach for the programmable tuning of noble-metal nanozymes' catalytic activity but also enlightened novel pathways for the operation of logic-empowered intelligent biosensors.