Light-converting microneedle patch for cutaneous UV phototherapy in psoriasis with enhanced safety and efficiency

Ultraviolet (UV) phototherapy stands as a pivotal clinical approach for managing diverse skin diseases. However, its application is constrained by concerns over UV-induced toxicity and imprecise photosensitizer delivery. This work introduces a light-converting microneedle patch (EU-MN), exemplified by its remarkable efficacy in psoriasis treatment. The EU-MN patch could release upconversion nanoparticles (UCNPs) and the photosensitizer methoxypsoralen (MOP) in controlled amounts in response to elevated matrix metalloproteinase (MMP) levels within the skin. Under near-infrared (NIR) excitation, UCNPs emit UV light (345/361 nm), which is combined with MOP to achieve more precise intradermal UV photochemotherapy, effectively inhibiting abnormal proliferation of human immortalized epidermal cells (HaCaT) and bacterial growth (Staphylococcus aureus and Escherichia coli). Comet assay highlights DNA damage correlation. In addition, the microneedles, designed with a reactive oxygen species (ROS)-responsive shell, release epigallocatechin gallate (EGCG) to counteract excessive inflammation and mitigate UV-induced damage. In psoriasis mice, the EU-MN patch demonstrates significant therapeutic efficacy and recurrence prevention. As further evidenced by the suppression of epidermal hyperplasia and inflammation (through RNA sequencing identifying cell cycle arrest), this EU-MN patch offers a safer, more precise, and more effective alternative strategy for conventional direct UV phototherapy.