Phycoerythrin belongs to the category of phycobiliprotein mainly present in the red algae with marvellous antioxidant and anticancer effects. In this study, we developed a dual antioxidant-photosensitizing hydrogel, CS-ZnPcTA/PE, based on chitosan (CS), zinc phthalocyanine tetra-aldehyde (ZnPcTA), and B-phycoerythrin (B-PE). ZnPcTA served as both a cross-linking and photosensitizing agent, while B-PE acted as an antioxidant and photosensitizer. The hydrogel was characterized using FT-IR, UV-Vis spectroscopy, FE-SEM, and swelling measurements. FE-SEM images confirmed a porous structure with pore sizes ranging from 50 to 470 nm, facilitating efficient oxygen transport. The swelling behaviours of the CS-ZnPcTA/PE with respect to different ratio of B-PE to ZnPcTA were investigated in different pHs. Swelling studies revealed that CS-ZnPcTA/PE (0.85%) exhibited the lowest swelling ratio whereas CS-ZnPcTA showed the highest. The antioxidant activity of B-PE in solution (CS/PE) and hydrogel network was compared. Radical scavenging efficiency of CS/PE, CS-ZnPcTA/PE (0.85%), CS-ZnPcTA/PE (0.55%) and CS-ZnPcTA/PE (0.34%) were about 80%, 57%, 40% and 38%, respectively. The CS-ZnPcTA/PE activity in photosensitizing process was investigated by measuring the degradation rate of 1,3-diphenylisobenzofuran in DMF upon (red) photoexcitation of photosensitizers. The relative singlet oxygen quantum yield of CS-ZnPcTA/PE (0.34%), ZnPcTA/PE (0.55%) and ZnPcTA/PE (0.85%) were 8, 4.5 and 3.5, respectively. These results highlight the synergistic effect of ZnPcTA and B-PE, enhancing singlet oxygen generation by up to 16-fold compared to single-photosensitizer systems, making CS-ZnPcTA/PE a promising candidate for cancer therapeutic applications.
