Recent advances in developing bioactive porous organic cages for fluorescence bioimaging, drug delivery, and therapies

Porous organic cages (POCs) are a class of covalently-linked three-dimensional materials with precise molecular structures, well-defined intrinsic cavities, and versatile tunabilities. Many POCs were primarily linked through dynamic reversible imine bonds, which resulted in limited stability under aqueous and harsh conditions. This instability has restricted their broader research and application potential, particularly in biomedical fields. Recently, significant advancements in the fabrication of water-soluble and stable POCs have opened up opportunities for diverse applications, such as host-guest chemistry, sensing, separation, and biological imaging and therapies. This review focuses on recently emerged POCs for diverse biomedical applications, including fluorescence bioimaging, drug delivery, and therapies. To provide a systematic summary and comprehensive discussion of these newly developed POCs, their synthetic strategies, unique bioactive properties, and biomedical applications are highlighted. The outlook emphasizes the remaining challenges and structural design guidance toward the development of new POCs for further inspiration of future biomedical investigations.