Preparation and characterization of a novel hybrid hydrogel shell for localized photodynamic therapy

Due to the limits of photodynamic therapy (PDT) in clinical use, the development of a new system for PDT may hold promise to improve the situation. In this article, we report the preparation of a novel hybrid hydrogel (HHG) containing poly (ethylene glycol) double acrylates (PEGDA), polyethylene glycol 400 (PEG400), phthalocyanine zinc (ZnPc) and phosphotungstic acid (PTA) based on in situ photopolymerization. ZnPc is used as both the photoinitiator for initiating the formation of HHG and the photosensitizer for producing singlet oxygen to kill tumor cells. PTA plays a significant co-initiator role in the photopolymerization process and has a positive impact on the acceleration of singlet oxygen generation. The HHG shows good biocompatibility, swelling and drug retention abilities, and especially can be easily and rapidly formed on tumor cells in situ by irradiating the precursor with near-infrared light. The HHG shell not only prevents diffusion of the photosensitizer, but also maintains a high ZnPc concentration in or on tumor cells for more effective PDT. Thus, this novel HHG is an attractive candidate for local PDT and has a huge potential application in the future development of cancer treatment.