Preparation of OVA-loaded -PGA/CS nanocomposite delivery vector and its immune response

To improve the stability and immunization of proteins or peptides after vaccination, choosing biodegradable and biocompatible materials to encapsulate protein ovalbumin (OVA) is necessary. In this study, we aim to construct OVA-loaded gamma-polyglutamic acid (gamma-PGA)/chitosan (CS) nanoparticles (NPs) using ionic cross-linking and poly-electrolyte composite methods and to explore its immune effect in mice. The as-constructed gamma-PGA/CS/OVA NPs, with a positive charge on the surface, were uniformly round. Additionally, the particle size range of the as-constructed gamma-PGA/CS/OVA NPs was 200-400 nm. Furthermore, the sodium dodecyl sulfate (SDS)-PAGE analysis showed that OVA in gamma-PGA/CS/OVA NPs had high structural integrity. The conditions of preparing gamma-PGA/CS/OVA NPs were optimized in detail, and it was found that the resultant loading capacity of NPs achieved 207.7 +/- 11.1 mu g/mg. MTT assay showed that gamma-PGA/CS NPs have good biocompatibility. The results of immune experiments in mice showed that compared with OVA not wrapped with gamma-PGA/CS composite carrier, gamma-PGA/CS/OVA NPs can induce a stronger immune response through humoral immunity in vivo. Overall, these findings demonstrated that gamma-PGA/CS NPs can be regarded as a good protein delivery system to enhance the immune response in vivo.