Preparation, Characterization, and Immune Activity of Viola philippica Polysaccharide PLGA Nanoparticles

ABSTRACT Recent pharmacological studies have demonstrated that Viola philippica polysaccharide (VPP) exhibits a modulating effect on immune activity. However, its utilization has been hampered by its large particle size and complex spatial structure. Polylactic‐ co ‐glycolic acid (PLGA) copolymer is recognized as an effective drug delivery carrier, exhibiting excellent biochemical properties. In this experiment, VPP was encapsulated with PLGA to form VPP PLGA nanoparticles (VPP–PLGA NPs). The morphological structure and immunomodulatory effects of VPP–PLGA NPs were evaluated. The particle size of VPP–PLGA NPs was reduced compared to VPP, and the optimal preparation conditions were as follows: The ratio of the organic phase to the internal aqueous phase was 8:1, the ratio of the external aqueous phase to the primary emulsion was 7:1, and the concentration of PLGA was 20 mg/mL. Additionally, VPP–PLGA NPs significantly increased the nitric oxide (NO) content, IL‐4, and IFN‐γ levels in RAW264.7 cells, as well as enhanced their phagocytic activity. Furthermore, VPP–PLGA NPs were found to increase NO content and IFN‐γ secretion in bone marrow–derived dendritic cells (BMDCs). These findings suggest that VPP–PLGA NPs could enhance the immune activity and may be utilized as a VPP delivery system for inducing strong immune responses.