Preparation, Characterization and In Vitro Evaluation of Liposome-Coated Alginate Nanoparticle as Immune Adjuvant Candidate in RAW 264.7 Cells

Complexing liposomes with polymers enhances the structural integrity and stability of the liposome membrane. Alginate, a biocompatible, biodegradable, and non-toxic polymer, emerges as a promising candidate for such complexation with liposomes. Notably, sodium alginate exhibits immunostimulant activity due to its inclusion of pathogen-associated molecular patterns (PAMPs), which are efficiently recognized by the body's immune receptors. In this study, liposomes were integrated with alginate nanoparticles through the addition of calcium chloride (CaCl₂) at three distinct concentrations (0.16%, 0.32%, 0.64%). The resultant liposome-alginate nanoparticles were characterized using a particle size analyzer (PSA) to determine their size, size distribution, and zeta potential. The encapsulation efficiency of lysozyme within the liposome-alginate nanoparticles was quantified utilizing a UV-visible spectrophotometer. Furthermore, this combination was assessed for its biological activity, specifically nitric oxide (NO) release and cell viability in vitro, using the RAW 264.7 cell line. Liposomes complexed with alginate nanoparticles at CaCl₂ concentrations of 0.16%, 0.32%, and 0.64% exhibited particle sizes of 281.7nm, 257nm, and 274.1nm, respectively, with polydispersity indices (PDI) of 0.389, 0.248, and 0.365, and zeta potentials of -0.874mV, -2.404mV, and -0.256mV, respectively. The data indicated that alginate concentration significantly influenced NO release (p<0.05) and RAW 264.7 cell viability (p<0.05). The incorporation of alginate into liposome formulations as a vaccine adjuvant not only enhances the physicochemical properties but also augments the efficacy of liposome adjuvants in stimulating NO production and promoting RAW 264.7 cell viability.