Vitiligo, a common skin disease that seriously affects 0.5−2.0% of the worldwide population, lacks approved therapeutics due to a wide range of adverse side effects. As a key regulator of skin pigmentation, MC1R may be an effective therapeutic target for vitiligo. Herein, we report an MC1R peptide agonist that directly self-assembles into nanofibrils that form a hydrogel matrix under normal physiological conditions. This hydrogel exhibits higher stability than free peptides, sustained release, rapid recovery from shear-thinning, and resistance to enzymatic proteolysis. Furthermore, this peptidal MC1R agonist upregulates tyrosinase, tyrosinase-related protein-1 (TYRP-1), and tyrosinase-related protein-2 (TYRP-2) to stimulate melanin synthesis. More importantly, MC1R agonist hydrogel promotes skin pigmentation in mice more potently than free MC1R agonist. This study supports the development of this MC1R agonist hydrogel as a promising pharmacological intervention for vitiligo.

The abuse of antibiotics has led to the emergence of various drug-resistant bacterial strains that threaten human health. Other than a continuous screen for antibiotics, alternative strategies need to be adopted to inhibit bacterial invasion. Herein, we de novo designed a self-assembling peptide that contains a bacteria-binding domain, a linker, and a self-assembly motif. This peptide could specifically bind with a surface protein on Staphylococcus aureus, subsequently self-assemble to form nanofibers, and selectively engulf and trap the bacteria. Thus, these trapped bacteria lack the ability to invade host cells and are unable to form a biofilm. More importantly, the designed peptide is nontoxic to human cells. Such a “trap but not kill” strategy could serve as an alternative to conventional antibiotics and shows great potential for treating bacteria.