Enhanced Anti-Psoriasis Efficacy of Curcumin via Optimized Nanostructured Lipid Carrier-Embedded Nanogel System

Psoriasis is a chronic inflammatory skin disorder in which existing topical and systemic therapies are often limited by adverse effects and poor patient compliance. This study aimed to develop a curcumin-loaded solid lipid nanoparticle CUR-SLN (curcumin solid lipid nanoparticles) loaded nanogel to enhance topical delivery and therapeutic efficacy. CUR-SLNs were prepared using a solvent diffusion method and characterized for particle size, polydispersity index (PDI), zeta potential, entrapment efficiency, and morphology. The optimized nanoparticles (133.90 ± 2.45 nm; PDI 0.325 ± 0.21; entrapment efficiency 89.50% ± 4.52%) were incorporated into a Carbopol-based gel to formulate the CUR-SLN nanogel. The nanogel was evaluated for appearance, viscosity, pH, and texture profile, along with in vitro drug release, ex vivo skin permeation, drug retention, and stability. Compared with a conventional curcumin gel, the CUR-SLN-loaded nanogel demonstrated sustained drug release over 48 h and significantly enhanced skin permeation and retention. In vivo studies in a psoriasis-induced mouse model showed a marked reduction in Psoriasis Area and Severity Index scores and significant downregulation of key pro-inflammatory cytokines (interferon-α [IFN-α], IL-23, interleukin-17 [IL-17], tumor necrosis factor-α [TNF-α]) (p < 0.001). Histological evaluation further confirmed restoration of normal skin structure in treated animals. Overall, the CUR-SLN-loaded nanogel represents a promising and safer topical therapeutic strategy for psoriasis, supporting its potential for further clinical development.