Constructing multifunctional bionic microspheres based on lignin/silk fibroin/hyaluronic acid for natural sunscreens...

Considering the health and safety effects of the active components in current sunscreens has inspired the enthusiasm for developing biocompatible alternatives, especially from nature. However, natural active ingredients have inherent drawbacks, such as dark-colored lignin and easily oxidized polyphenols, which are difficult to meet the requirements of smart sunscreens. Integrating two or more natural sunscreens in a single unit can overcome the shortcomings of a single active ingredients and synergistically enhance ultraviolet (UV) radiation protection. Herein, a composite microsphere (HCAS) was fabricated by incorporating dopamine modified lignin, silk fibroin, phenylboronic acid modified hyaluronic acid and chlorogenic acid through self-crosslinking of boric acid ester bonds and using genipin as assistant cross-linker. This multi-component coordination strategy imparts HCAS microspheres with superior UV protection performance and photostability under UV exposure. The remarkable properties of HCAS are evidenced by its high sun protection factor (SPF) of 55 when incorporated at 10% into a base cream, representing a significant improvement in color clarity compared to lignin-based formulations. Notably, HCAS exhibited exceptional antioxidant activity, capable of effectively eliminating reactive oxygen free radicals (DPPH•, OH• and O₂•^-). Furthermore, HCAS microspheres demonstrate excellent interfacial activity, functioning as an efficient Pickering stabilizer under various conditions. In vitro biological evaluations confirmed that HCAS not only has good biocompatibility but also shows the potential to promote cell growth. This study demonstrates that integration of multi-component natural ingredients for synergistically enhancing UV performances is an effective strategy for future sunscreens development.