Emerging metallenes: synthesis strategies, biological effects and biomedical applications.

Metallenes, atomically thin-layered materials composed of coordination-deficient metal atoms, have emerged as a new category of two-dimensional materials. Metallenes exhibit exciting properties with a fusion of atom economy, ultrathin structure, photonic properties, and catalytic activity, which make them intriguing for a wide range of applications in biomedicine. The development of biomedical applications of metallenes is in its infancy yet fast-growing. In this review, after a brief introduction of the definition, structures, properties, and classification of metallenes, we outline two common synthesis strategies and identify their shortcomings. Then, we comprehensively discuss the biological effects of metallenes, such as nano-biointeractions and signaling pathway regulation. We also highlight their recent advances in biomedical applications, including antitumor, biosensing, bioimaging, antibacterial, and anti-inflammation. Finally, we provide personal perspectives on remaining challenges and future opportunities for the biomedical applications of metallenes.