Adhesive-Yet-Removable Silica-Polydopamine Janus Particles for High-Performance Skin Photoprotection

Photoprotective materials must remain on the skin during use while permitting gentle removal afterward, creating a conflict between durable adhesion and post-use cleansing. Here, we report anisotropic dumbbell-shaped mesoporous Silica-Polydopamine Janus particles (SiO2&PDA JPs) designed to balance these competing requirements at the skin interface. The hydrophilic silica domain suppresses PDA aggregation and serves as a carrier for avobenzone, whereas the PDA domain provides broadband ultraviolet shielding, radical-scavenging activity, and skin adhesion. Under continuous ultraviolet irradiation, more than 70% of avobenzone remained in the Janus system after 4 h, compared with approximately 10% for free avobenzone. Ex vivo imaging indicated that the SiO2&PDA JPs were predominantly confined to the skin surface, and in vivo fluorescence imaging showed approximately 60% retention after 6 h of unrestricted mouse activity. The particles resisted water rinsing but were substantially removed by wet-towel wiping. Their adsorption at oil-water interfaces and reduction of interfacial tension further promoted emulsification-assisted removal of oily residues under gentle rubbing. In HaCaT cells, the Janus formulation reduced ultraviolet-induced reactive oxygen species accumulation, mitochondrial depolarization, and γH2AX formation. In a mouse model, it attenuated epidermal thickening and ultraviolet-associated DNA damage. These results identify anisotropic SiO2&PDA JPs as an adhesive-yet-removable skin-interfacing biomaterial integrating ultraviolet-filter stabilization, radical-scavenging activity, surface retention, and practical cleansing.