Preparation Of Particle Stabilized Bubble And Its Application As Vaccine Adjuvant

Vaccination has long been the most effective,long-lasting,and cost-effective method of protecting against and treating infectious diseases.However,contemporary biotechnologically produced vaccines are less immunogenic,and the advent of adjuvants can effectively enhance the immune response,reduce the number of antigens,and improve vaccine efficacy.The types of adjuvants currently applied are mainly traditional single adjuvants such as aluminum adjuvant and oil emulsion adjuvant,among which aluminum salt adjuvant has poor cellular immune effect and oil emulsion adjuvant is irritating to the organism.In order to overcome the drawbacks of single adjuvants,new compound adjuvants need to be developed.The paper proposes to combine particles and bubbles to form a particle-stabilized bubble structure and to explore the potential of particle-stabilized bubbles as a novel vaccine adjuvant.Details of the study are as follows:(1)Chitosan nanoparticles were prepared by nanoprecipitation method and poly(lactic acid)-hydroxyacetic acid copolymer(PLGA)nanoparticles were prepared by emulsification solvent volatilization method.The type and concentration of chitosan were explored,and the conditions of oil-water ratio,sonication conditions,polyvinyl alcohol(PVA)concentration,external aqueous phase,and type of PLGA were optimized.The optimized chitosan particle size was 303.3 ± 3.90 nm and contact angle was 45.2 ± 2.6°,and the particle size of five PLGA nanoparticles ranged from 200 to 350 nm and contact angle ranged from 64 to 66°.(2)Preparation of particle-stabilized bubbles and investigation of the factors influencing particle-stabilized bubbles The conditions of external aqueous phase,particle morphology and particle type were optimized to successfully prepare PLGA particle-stabilized bubbles(PPSBs).The length of PLGA particle-stabilized bubbles was up to 48 h under the condition of glycerol concentration of 0.1%.(3)To explore the application potential of PPSBs as vaccine adjuvants,the effects of PPSBs on endocytosis as well as activation of dendritic cells(DC cells)were investigated,and the immune efficacy and safety evaluation of PPSBs as vaccine adjuvants were performed.It was found that PPSBs could promote the endocytosis of DC cells,and could promote the high expression of antigen differentiation cluster 80(CD80)and leukocyte differentiation antigen 86(CD86)molecules on the surface of DC cells,fully activating the antigen-presentation function of DC cells.Animal experiments were conducted and revealed good humoral and cellular immune effects,with PPSBs effectively promoting higher expression of ovalbumin peptide segment major tissue complex(SIINFEKL MHC Ⅰ)and CD127 molecules on the surface of T lymphocytes(CD8+T)cells,indicating that PPSBs enhanced cross-presentation of antigens and cellular immune effects.Therefore,PPSBs are considered to have potential for application as vaccine adjuvants.