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.