Formulation and Biological Evaluation of Curcumin-Loaded Liposomes and PLA Nanoparticles against Oxidative Injury in NRK-52E Cells

Abstract

Curcumin is a natural polyphenol with antioxidant and anti-inflammatory properties. However, its low aqueous solubility and poor oral bioavailability limit clinical translation. In this study, curcumin was encapsulated into liposomes and PLA nanoparticles to evaluate formulation characteristics and biological effects in renal NRK-52E cells. Liposomal stability was assessed over 10 days using particle size distribution and zeta potential measurements, and physical observations indicated aggregation/precipitation from day 3 onward, with discontinuation after day 10 due to visible fungal-like growth. For PLA nanoparticles, thermal analysis suggested retention of the PLA glass transition. Drug loading was quantified by encapsulation efficiency (EE) and drug loading efficiency (LE). Curcumin-loaded formulations were evaluated for cytotoxicity and oxidative-stress modulation using MTT and LDH assays after exposure to either curcumin in different forms or the oxidative agent paraquat (PQ). At low curcumin concentrations, minimal changes were observed in viability and membrane integrity, whereas higher doses reduced cell viability and increased LDH release, with effects varying by formulation. During PQ challenge experiments, curcumin encapsulated in liposomes or PLA nanoparticles produced inconsistent outcomes and did not uniformly ameliorate oxidative injury. Overall, the results highlight formulation-dependent biological effects and underscore the need for assay-interference controls when evaluating curcumin in LDH-based readouts.