Design of Tween80/oleic acid composite vesicle and its application in controlled release of vitamin C

Fatty acid vesicles (FAVs), with their unique bionic structure, play a crucial role in models for protocells, food manufacturing, and drug delivery systems. However, FAVs are highly sensitive to changes in pH, which imposes strict constraints on their development in food and medicine. Therefore, in this study, the pH window of vesicles formed by oleic acid (OA) was migrated and expanded by introducing a nonionic surfactant, Tween80 (TW80), which resulted in a more stable pH environment for FAVs. Acid-base titration combined with particle size confirmed that different ratios of TW80 and OA expanded the pH window from 8.2-10 to 1.99-7.49, as determined by potential and turbidity. The intermolecular forces of TW80/OA composite vesicles were determined by infrared spectroscopy. Vitamin C (VC) was used as a model drug, and the TW80/OA/VC vesicles showed an encapsulation rate of 48.87% and a drug-loading capacity of 13.13% at a VC concentration of 1 mg/mL, pH = 5.5, and T = 25 degrees C. The vesicles were also found to have a high VC concentration and a high drug loading capacity. The in vitro release experiments demonstrated that the TW80/OA/VC vesicles could accomplish the drug release process in a physiological environment. The results of in vitro free radical scavenging experiments showed that the TW80/OA/VC vesicles could maximize the scavenging rate of DPPH free radicals up to 97.61%. This study can provide a fundamental theoretical basis for applying drug carrier vesicles in cosmetics.