Palladium-Based Nanozymes: From Synthesis and Activity Modulation to Biomedical Applications

Palladium (Pd)-based nanozymes have emerged as a prominent research focus in the field of noble metal nanozymes due to their tunable d-band centers, diverse facet structures, and exceptional biocompatibility. Despite the abundance of studies demonstrating the versatile utilities of Pd-based nanozymes with varied morphologies and catalytic activities in biomedical settings, the absence of a systematic and comprehensive summary of these research advances impedes their further development and clinical translation. In this review, we first briefly discuss the structural design principles and synthesis strategies of both elementary and composite Pd-based nanozymes. Subsequently, an in-depth analysis is conducted on their enzyme-like activities (e.g., peroxidase-like, oxidase-like, catalase-like) and corresponding modulation approaches (e.g., structural engineering, surface modification, composite construction). Building on this foundation, we highlight the cutting-edge biomedical applications across multiple scenarios, including medical diagnostics, disease treatment (e.g., cancer therapy, anti-inflammation) and radiation-related biomedical applications. Furthermore, the biosafety evaluation of Pd-based nanozymes, a critical prerequisite for clinical translation, is emphasized. Finally, this review summarizes the limitations of current research and identifies critical bottlenecks that need to be addressed to advance the future development and practical application of Pd-based nanozymes.