Preparation of Cod Skin Collagen Peptides/Chitosan-Based Temperature-Sensitive Gel and Its Anti-Photoaging Effect in Skin.

Background: Photoaging decreases quality of life and increases the risk of skin cancer, underscoring the urgent need to explore natural, high-efficacy, anti-skin photoaging (SP) active substances. Methods: In this study, a gel (CS/CSCPs/ß-GP gel) was prepared using chitosan (CS) and sodium ß-glycerophosphate (ß-GP) through crosslinking with small molecular CSCPs as the carried drug. We evaluated its structural characteristics and properties. The effect of CS/CSCPs/ß-GP gel on the degree of ultraviolet (UV)-induced skin aging of mice was investigated through comparative analysis of skin damage, the integrity of collagen tissues and elastic fibers, levels of reactive oxygen species (ROS) and key inflammatory factors (tumor necrosis factor [TNF]-α and interleukin [IL]-1ß, IL-6, and IL-10), and tissue expression of matrix metalloproteinase-3 (MMP-3) after repeated UV irradiation in a nude mice SP model. Results: The results showed that CS/CSCPs/ß-GP gel was successfully prepared and had the desired characteristics. Compared with CSCPs alone, the CS/CSCPs/ß-GP gel more evidently improved typical photoaging characteristics on mouse dorsal skin. It also increased the moisture content, causing the skin to become glossy and elastic. Pathological skin analysis revealed that this peptide-carrying gel can effectively inhibit epidermal thickening, reduce tissue inflammatory infiltration, suppress collagen fiber degradation, increase the collagen content, alleviate structural elastic fiber damage, and significantly inhibit abnormal MMP-3 expression. In addition, biochemical analysis showed that the CS/CSCPs/ß-GP gel can effectively inhibit the elevated expressions of ROS and key proinflammatory factors (TNF-α, IL-1ß, IL-6) in photoaging skin tissues and promote expression of the anti-inflammatory factor IL-10. Conclusion: SP can cause many clinical skin diseases, such as solar freckle-like nevus, solar keratosis, cutaneous melanoma, and squamous cell carcinoma. CSCPs are a high-efficacy anti-SP natural active substance and CS/CSCPs/ß-GP gel can synergistically enhance the CSCPs' anti-SP effect. The mechanism is likely related to the inhibited activation of ROS/nuclear transcription factor-κB signaling and the expression of downstream inflammatory factors.