Recent advances of multi-dimensional porphyrin-based functional materials in photodynamic therapy

Photodynamic therapy (PDT) has emerged as a promising and non-invasive modality for cancer treatments. Photosensitizers, as one of the essential elements in PDT, play a crucial role in the practical applications of PDT. Exposure to suitable light irradiation leads these photosensitizers to absorb the energy and move to excited state. Eventually, they transfer the energy to surrounding molecules and produce reactive oxygen species (ROS), particularly the singlet oxygen (1O2). Porphyrins, consisting of tetrapyrrole bridged with four methylene groups, are the classical and typical photosensitizers. However, the poor water-solubility, low biostability and non-specific tumor-targeting properties of porphyrins limit the PDT efficiency and their clinical applications. Thus, in order to promote the PDT efficiency of porphyrins, a variety of modification and functionalization strategies have been developed to construct multi-dimensional porphyrin-based functional materials. Herein, we summarize the recent advances of porphyrin-based functional materials from the following aspects: (1) the porphyrinic amphiphiles, (2) physical encapsulation of porphyrins by nanoparticles, (3) the construction of porphyrin-based polymers including block copolymers with covalent bonding and supramolecular polymers with non-covalent bonding, and (4) porphyrin-based organic frameworks. We believe that the development of porphyrin-based functional materials provide more fascinating superiorities in PDT and dramatically expand the potentials and possibilities in cancer treatments.