Development and characterization of β-Sitosterol-Stabilized Paclitaxel-Loaded Liposomes with Superior Bilayer Integrity and Stability for Optimized Drug Delivery

Abstract Purpose Paclitaxel’s clinical utility is limited by poor aqueous solubility and toxicities from Cremophor EL vehicles. This study developed a novel liposomal formulation by substituting cholesterol with β-sitosterol to enhance bilayer integrity, physicochemical stability, drug retention, and overcome these limitations. Procedures Liposomal paclitaxel was prepared via modified thin-film hydration technique, replacing cholesterol with β-sitosterol. Formulations were characterized for particle size, zeta potential, entrapment efficiency, and morphology using cryo-TEM. Stability was evaluated by quantifying hydrolytic degradation products (Lyso-PC, Lyso-PG), in vitro release profiles, cytotoxicity and anti-migratory effects in MCF-7 breast cancer cells via MTT and wound healing assays, and plasma stability through size and drug retention monitoring after 24-hour incubation at 37°C. Results The optimized β-sitosterol-based liposomes (L-PTX C) displayed uniform unilamellar vesicles on cryo-TEM, achieved 98.66% drug entrapment efficiency, significantly reduced Lyso-PC and Lyso-PG byproducts, and provided sustained release without initial burst. In MCF-7 cells, L-PTX C exhibited superior cytotoxicity with IC₅₀ of 4.89 nM, six-fold lower than conventional paclitaxel (31.13 nM) and effectively inhibited cell migration. Plasma stability was maintained with consistent particle size and drug retention. Conclusions β-Sitosterol substitution thus offers a stable, Cremophor-free liposomal paclitaxel with enhanced efficacy for breast cancer therapy.