Upconversion-Based Photodynamic Therapy for Psoriatic Dermatitis.

Psoriasis, with a global incidence rate of 2%-3%, afflicts patients with persistent erythema and scales and is often accompanied by comorbidities such as arthritis and depression, significantly impairing their quality of life. While emerging biologics and traditional medications as well as phototherapy have made certain progress in treating psoriasis, these therapies are hindered by significant drawbacks including high costs, suboptimal efficacy, and significant side effects. Photodynamic therapy (PDT) has great potential for psoriasis treatment, but its application is limited due to the weak penetration of short-wavelength light used for active photosensitizer (PS). Upconversion nanoparticles (UCNPs) offer a promising solution for traditional PDT as they could be excited by near-infrared (NIR) light to emit UV-visible light for reactive oxygen species generation, which effectively addresses penetration challenges. In this study, PS (ZnPc) was encapsulated on UCNPs coated with a porous silica shell (UCNPs-ZnPc). When topically applied to psoriatic mice skin, UCNPs-ZnPc was taken up by macrophages. Upon activation with 980 nm NIR light, psoriatic dermatitis was treated since the macrophage viability was reduced, and the overproliferation of psoriatic skin cells was suppressed. These results highlight the potential of UCNPs-mediated PDT as an innovative approach to managing psoriasis.