Iridium-Based Nanomaterials: Precise Fabrication, Structural and Electronic Modulation, and Biomedical Applications

Iridium (Ir), a representative platinum-group metal, possesses unique 5d electronic structure, multiple accessible oxidation states, exceptional chemical stability, and highly tunable coordination chemistry, making it an attractive platform for biomedical nanotechnology. Recent advances in nanomaterial synthesis and interfacial engineering have enabled the development of diverse Ir-based nanomaterials, including coordination complexes, nanoparticles, single-atom nanocatalysts, and metal-organic frameworks, with precisely engineered electronic structures and catalytic properties. Through the rational regulation of valence states, crystal phases, defect structures, and metal-support interfacial interactions, these nanomaterials exhibit remarkable redox activity, enzyme-like catalysis, and responsiveness to external-field stimuli. In this review, we systematically summarize recent advances in the design, fabrication, structural and electronic engineering, physicochemical properties, and biological applications of Ir-based nanomaterials. Particular attention is given to their enzyme-mimetic activities, catalytic mechanisms, and unique bidirectional oxidative-antioxidative regulatory capabilities, as well as their cellular interactions and toxicological characteristics. We further summarize their emerging biomedical applications in biosensing, cancer therapy, and antimicrobial treatment, where catalytic regulation, tissue microenvironment modulation, and external-field-enhanced strategies collectively enable improved therapeutic performance. Finally, current challenges and future perspectives are discussed, including structure-activity relationship elucidation, intelligent stimulus-responsive therapeutic platforms, artificial intelligence (AI)-assisted materials discovery, long-term safety evaluation, and potential clinical translation.