Curcumin-Loaded Lipid Nanocarriers: A Targeted Approach for Combating Oxidative Stress in Skin Applications

Background/Objectives: Oxidative stress significantly impacts skin health, contributing to conditions like aging, pigmentation, and inflammatory disorders. Curcumin, with its potent antioxidant properties, faces challenges of low solubility, stability, and bioavailability. This study aimed to encapsulate curcumin in three lipid nanocarriers-solid lipid nanoparticles (SLNs), nanostructured lipid carriers (NLCs), and nanoemulsions (NEs)-to enhance its stability, bioavailability, and antioxidant efficacy for potential therapeutic applications in oxidative-stress-related skin disorders. Methods: The lipid nanocarriers were characterized for size, polydispersity index, ζ-potential, and encapsulation efficiency. Stability tests under various conditions and antioxidant activity assays (DPPH and FRAP methods) were conducted. Cytotoxicity in human dermal fibroblasts was assessed using MTT assays, while the expression of key antioxidant genes was evaluated in human dermal fibroblasts under oxidative stress. Skin penetration studies were performed to analyze curcumin's distribution across the stratum corneum layers. Results: All nanocarriers demonstrated high encapsulation efficiency and stability over 90 days. NLCs exhibited superior long-term stability and enhanced skin penetration, while NE formulations facilitated rapid antioxidant effects. Antioxidant assays confirmed that curcumin encapsulation preserved and enhanced its bioactivity, particularly in NLCs. Gene expression analysis revealed upregulation of key antioxidant markers (GPX1, GPX4, SOD1, KEAP1, and NRF2) with curcumin-loaded nanocarriers under oxidative and non-oxidative conditions. Cytotoxicity studies confirmed biocompatibility across all formulations. Conclusions: Lipid nanocarriers effectively enhance curcumin's stability, antioxidant activity, and skin penetration, presenting a targeted strategy for managing oxidative stress in skin applications. Their versatility offers opportunities for tailored therapeutic formulations addressing specific skin conditions, from chronic disorders like psoriasis to acute stress responses such as sunburn.