Bioinspired Janus Interpenetrating Dressing with Unidirectional Oil-Phase Biofluid Drainage for Enhanced Acne Healing.

Acne vulgaris is a prevalent chronic inflammatory skin condition driven by excessive sebum secretion and follicular blockage. While most existing acne patches emphasize downstream effects, such as antibacterial and anti-inflammatory effects, they neglect sebum accumulation, a key upstream factor. Efficient removal of this lipid-rich biofluid remains a major challenge. Although existing unidirectional drainage systems have shown success in managing aqueous wound exudates through capillary-driven flow, their designs are poorly suited for viscous, nonpolar secretions like sebum. Here, we present a Janus interpenetrating dressing (BJID) consisting of an oleophilic absorbing layer/underwater oleophobic barrier layer to form a structurally interlocked interface. Mimicking natural liquid collection and directional self-transport mechanisms, the BJID achieves unidirectional oil-phase sebum drainage while preventing backflow. Taking advantage of conical micropores, anisotropic wettability, and directional capillary forces, BJID enables a high rectification ratio of 4.4 and directional transport of sebum droplet while inhibiting reverse diffusion. It also reduces intracellular ROS and suppresses inflammation via the TLR2/NF-κB pathway in C. acnes-stimulated HaCaT cells. In a three-week human trial, BJID reduced acne size and sebum by 31.8% and 21.3% and increased skin hydration by 13.1%. These findings highlight the potential of bioinspired unidirectional oil-phase drainage materials as a new strategy for regulating skin microenvironments and improving acne therapy.