An overview of porphyrin-comprising supramolecular scaffolds for cancer phototherapy

Abstract

Photothermal and photodynamic treatments, as the primary branches of phototherapy, are derived from non-invasive therapies. Since metal–organic frameworks (MOFs) and covalent–organic frameworks (COFs) are advanced crystalline and highly porous materials, they have attracted considerable attention and played a significant role in phototherapy due to their innate porous structure, flexible design, regularity in structure, multifunctionality, and favorable biocompatibility. Porphyrin and its derivatives have emerged with outstanding electrochemical and photophysical characteristics, which have garnered remarkable attention in various fields, including catalysis, biosensing, solar cells, biomedical applications, and gas storage. Nonetheless, porphyrin's applicability in cancer phototherapy is limited due to its intrinsic limitations, such as weak absorption in the biological spectral window, poor optical and chemical stability, and self-quenching. Porphyrin-comprising MOFs and COFs, a group of new hybrid porous coordination polymers, are introduced to overcome the porphyrin's restrictions and develop its biomedical applicability. Encapsulating porphyrins into the pores of these supramolecular scaffolds, grafting porphyrins onto their surface, or utilizing porphyrins as structural organic linkers enables the combination of the particular characteristics of these supramolecular scaffolds and porphyrins, thereby overcoming the limitations of porphyrins in biomedical applications. This review provides a historical overview of cancer phototherapy, including a brief outline, synthesis routes, and the applications of porphyrin-comprising MOFs and COFs in phototherapy. Ultimately, the challenges and outlook on cancer phototherapy using these substances are debated.