Defective PdMo metallene with efficient catalase-like activity for sensitive immunoassay.

Nanozyme-involved biosensing platforms show great potential in the accurate detection of trace analytes. Nevertheless, the rational design of high-performance nanozymes remains a significant challenge. Overcoming this hurdle is crucial for developing advanced immunoassays and, ultimately, for the construction of portable point-of-care testing devices. We successfully synthesized ultrathin PdMo metallene nanosheets (d-PdMoene), featuring a high density of defects, exhibiting efficient catalase-like activity (CAT-like activity) capable of catalyzing H2O2 into H2O and O2. Theoretical calculations reveal that d-PdMoene exhibits significant charge redistribution and upward shift of the d-band center, suggesting a superior electronic configuration for catalysis and enhancement of H2O2 adsorption. Besides, compared to PdMoene, a weaker bonding interaction between O2∗ and the d-PdMoene promotes easier O2 release. The generated O2 induces noticeable pressure changes, which can be easily monitored by a portable pressure gauge. As a concept application, an immunoassay sensor for prostate specific antigen was established, demonstrating high sensitivity and selectivity. Beyond the immediate outcomes, this study carries broader implications. It establishes a robust framework for the rational design of high-performance nanozymes and, concurrently, outlines a practical pathway toward the realization of portable testing devices.