3D-Printed lesion-conformal light-guiding patches for precise and personalized psoriasis phototherapy

Psoriasis is a chronic inflammatory skin disorder marked by epidermal hyperplasia and hyperkeratosis, with lesions presenting highly irregular geometric patterns and a discrete distribution. Traditional phototherapy, lacking spatial selectivity, often causes radiation damage to surrounding healthy tissue, thereby limiting treatment dosage and frequency. In this study, we developed three-dimensional (3D)-printed lesion-conformal light-guiding patches, precisely customized based on lesion characteristics, marking a significant advancement from traditional point light sources to high-performance uniform surface light sources. The system integrates titanium dioxide nanoparticles (TiO₂NPs) within a polydimethylsiloxane (PDMS) matrix to form scattering centers. Through a lateral coupling design, it redirects photons, generating a highly uniform surface-emitting light field. This approach overcomes the intensity attenuation inherent to point sources, enabling the simultaneous irradiation of multiple plaques while sparing surrounding healthy tissue with precision. In an imiquimod (IMQ)-induced mouse model, this system significantly mitigated damage to normal skin while effectively repairing psoriatic lesions. Histopathological (HE) analysis revealed a dramatic increase in epidermal thickness in the model group, which was five times greater than that of the control group. In contrast, the patterned group exhibited notable improvements in the pathological features of the lesions, with epidermal thickness returning to levels comparable to those of healthy controls. Immunohistochemical analysis showed that in the patterned group the expression of the keratinocyte proliferation marker K16 and the inflammatory cytokine IL-17 was substantially reduced, demonstrating superior efficacy over conventional point-source irradiation. Additionally, this closed-loop system demonstrated promising therapeutic potential for refractory plaques in preliminary clinical cases, providing new insights for the development of next-generation personalized and precision dermatology treatment devices.