tThe major problems of porphyrins as promising materials for photodynamic therapy (PDT) are their lowsolubility, subsequently aggregation in biological environments, and a lack of tumor selectivity. With thisin mind, a chitosan-based hydrogel conjugated with tetrakis(4-aminophenyl)porphyrin (NH2-TPP) and2,4,6-tris(p-formylphenoxy)-1,3,5-triazine (TRIPOD) via Schiff base linkage, functionalized with folatewas designed and synthesized as a pH-sensitive, self-healable and injectable targeted PS delivery sys-tem. This new hydrogel was characterized by FT-IR,1H NMR, SEM, UV-vis, fluorescence spectroscopy andzeta potential. Formation of imine bonds with the aldehyde group of TRIPOD and amine group of NH2-TPPand chitosan, as a dynamic connection, was approved by rheological analysis. Spectroscopic character-izations revealed that aggregation of porphyrin in aqueous media was eliminated due to diminished stacking interaction of porphyrin in 3D cross-linked hydrogel structure. Hydrogel 3D microporousstructure efficiently transfers the excitation energy to the porphyrin unit, yielding improvement singletoxygen releases. Cytotoxicity and phototoxicity analysis of the CS/NH2-TPP/FA hydrogels indicating anexcellent capability to kill cancer cells selectively and prevent damage to normal cells. This work presentsa new and efficient model for the preparation of highly efficient and targeting photosensitizer deliverysystem.
