Preparation Of Modified PG/PLGA Biopolymer Vaccine Delivery System And Its Immune Response

Adjuvants,as important biological products,can greatly improve the immune effect of antigens;Thus,via developing novel vaccine adjuvants successfully,the effectiveness of vaccine immune has been enhanced significantly.Peach gum polysaccharide is a large polysaccharide widely found in nature and has good biocompatibility.By chemically modifying peach gum polysaccharide,its molecular structure is changed to give it new physicochemical properties.In this paper,the modified peach gum polysaccharide was used as a material to prepare oral vaccine and injectable vaccine respectively by loading model antigen OVA,and the ability of modified peach gum polysaccharide as an adjuvant to protect antigen in acidic environment and induce immune enhancement in vivo was investigated.1.Carboxymethylated peach gum（CPG）was prepared using peach gum（PG）as raw material.The successful modification of carboxymethylation was determined by correlation analysis and characterization means.The OVA-loaded microsphere particles（CPG-OVA MPs）were prepared by emulsification and ionic cross-linking methods.The prepared CPG-OVA MPs were spherical particles with 12-14 μm diameter,and the LC of CPG-OVA MPs was 224.4±4.6 mg/g.The in vitro release of CPG-OVA MPs in different p H solutions as well as in simulated gastrointestinal environment.The results indicated that CPG-OVA MPs had anti-acid properties.The cytotoxic effect of CPG-OVA MPs on IPECJ2 was analyzed by CCK-8 method,and the results showed that CPG-OVA MPs have good biocompatibility.2.The PG was modified by quaternization to prepare quaternized peach gum（QPG）,and the successful modification of quaternization was determined by correlation analysis and characterization means.The QPG/PLGA-OVA NPs were prepared by double emulsification method,and the prepared QPG/PLGA-OVA NPs had a particle size of 100-160 nm,a surface potential of 15.3±0.4 m V,an encapsulation rate of 75.4±1.1 %,and a drug loading capacity of 177.7±4.1 mg/g.The QPG/PLGA-OVA NPs were able to release slowly and persistently antigen with slow release function.The cytotoxic effect of QPG/PLGA-OVA NPs on mouse RAW264.7 was analyzed by CCK-8 method,and the results showed that QPG/PLGA-OVA NPs have good biocompatibility.The results in mice showed that QPG/PLGA-OVA NPs were effective in enhancing the immune response in vivo.The results of cytotoxicity experiments with QPG/PLGA NPs against veterinary adjuvant MONTANIDE^TM GEL 01 from SEPPIC（France）,showed that their biosafety was significantly higher than that of MONTANIDE^TM GEL 01.Thus,QPG/PLGA NPs modified with natural polysaccharides had good biocompatibility while inducing enhanced in vivo mouse immune response in mice,which has potential applications in the field of vaccine delivery.