ABSTRACT
With the continuous development of preventive and therapeutic vaccines, traditional adjuvants cannot provide sufficient immune efficacy and it is of high necessity to develop safe and effective novel nanoparticle-based vaccine adjuvants. α-Tocopherol (TOC) is commonly used in oil-emulsion adjuvant systems as an immune enhancer, yet its bioavailability is limited by poor water solubility. This study aims to develop TOC-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (TOC-PLGA NPs) to explore the potential of TOC-PLGA NPs as a novel nanoparticle-immune adjuvant. TOC-PLGA NPs are prepared by a nanoprecipitation method and their physicochemical properties are characterized. It is shown that TOC-PLGA NPs are 110.8 nm, polydispersity index value of 0.042, and Zeta potential of -13.26 mV. The encapsulation efficiency and drug loading of NPs are 82.57% and 11.80%, respectively, and the cumulative release after 35 days of in vitro testing reaches 47%. Furthermore, TOC-PLGA NPs demonstrate a superior promotion effect on RAW 264.7 cell proliferation compared to PLGA NPs, being well phagocytosed and also promoting antigen uptake by macrophages. TOC-PLGA NPs can strongly upregulate the expression of co-stimulatory surface molecules and the secretion of cytokines. In conclusion, TOC-PLGA NPs can be a novel vaccine adjuvant with excellent biocompatibility and significant immune-enhancing activity.
