Herbal medicine-derived carbon quantum dots in thermosensitive hydrogel: A multifunctional therapeutic strategy for UVB-induced photodamage.

Overexposure to ultraviolet B (UVB) radiation induces oxidative stress, inflammation, and apoptosis, which accelerates collagen degradation and skin aging. Current strategies for managing photodamage mainly focus on sun protection and skin repair; however, comprehensive therapeutic approaches are urgently needed. Herbal medicine-derived materials have shown great promise in combating photodamage. Modified Qing'e Formula (MQEF) has demonstrated the ability to treat photodamage by restoring redox homeostasis and is considered an effective anti-photodamage herbal remedy. However, the traditional oral decoction limits its application in topical treatments. In this study, we synthesized novel multifunctional carbon quantum dots (CQDs) using MQEF as a precursor (MQEF-CQDs). These CQDs exhibit superior antioxidant capacity compared to traditional herbal extracts and show no significant toxicity to HaCaT cells, indicating good biocompatibility and potential for skin drug delivery. Furthermore, MQEF-CQDs were incorporated into a thermosensitive hydrogel to form a MQEF-CQDs-hydrogel (MQEF-CQDs-gel) dressing, which is better suited for external use. This hydrogel displays temperature, pH, and rheological properties that align with the skin's physiological environment, along with dual functions of antimicrobial and restorative actions. Both in vitro and in vivo experiments demonstrate that MQEF-CQDs and MQEF-CQDs-gel mitigate UVB-induced photodamage through antioxidant, anti-inflammatory, anti-apoptotic, and collagen degradation-inhibition pathways. Additionally, MQEF-CQDs-gel significantly reduces skin damage, promotes the reconstruction of the epidermal structure, and restores damaged collagen fibers. These findings indicate that MQEF-CQDs represent a promising pathway for the green and sustainable production of herbal-based medicines, with broad industrial applications and as a potent candidate for photodamage treatment.