Modification Of Polyethylenimide And Its Adjuvant Properties

As a cationic polymer,polyethyleneimine(PEI)has a good gene transfection effect as a gene transfection reagent,and has attracted much attention in the field of vaccine adjuvant because of its excellent proton sponge effect.Despite PEI has the high transfection efficiency,its high toxicity due to its high positive charge density limits its application.In this paper,the molecular weight of 25 k Da PEI was modified with mannose,stearyl chloride and the both.The aim is to reduce the positive charge density of PEI and to improve its phagocytsis and immunomodulatory.The average particle size,stability and specific Ig G of the composite particles with modified PEI and antigen OVA were characterized.The endocytosis effect of mannose/stearyl chloride-modified PEI and OVA composite particles on macrophages was evaluated.The main research contents are as follows:(1)A series of mannose-modified polyethylenimine(Man-PEI)were prepared by nucleophilic addition reaction using mannose with immune regulatory effects and PEI.Its structure was characterized by fourier transform infrared(FT-IR)spectroscopy and hydrogen nuclear magnetic(~1H NMR)spectrum.When the mass ratio of Man-PEI to OVA was 0.04,the composite nanoparticles with particle size less than 200 nm were obtained.The composite particle has good storage stability at 4℃.Mannose-introduced Man-PEI significantly increased the specific immune response to OVA antigen compared with pure PEI.(2)Polyethylenimide was modified by stearyl chloride,and a series of stearyl chloride-modified polyethylenimide(SA-PEI)was prepared by the reaction of acyl chloride and amine group.Its structure was characterized by fourier transform infrared(FT-IR)spectroscopy and hydrogen nuclear magnetic(~1H NMR)spectrum.The mean particle size,polydispersion index,Zeta potential,stability and adsorption rate of stearyl chloride-modified PEI to OVA were investigated systematicazetally.When the mass ratio of SA-PEI to OVA was 0.04,composite nanoparticles with particle size less than 200 nm were obtained.The composite particle has good storage stability at 4℃.SA-PEI significantly increased the specific immune response to OVA antigen compared with pure PEI.(3)In order to obtain more effective vaccine adjuvant,mannose-stearyl chloride-modified polyethylimide(SA-Man-PEI)was prepared by double modification of mannose and stearyl chloride.Its structure was characterized by fourier transform infrared(FT-IR)spectroscopy and hydrogen nuclear magnetic(~1H NMR)spectrum.When the mass ratio of SA-Man-PEI to model antigen OVA was 0.04,composite particles with particle size less than 200 nm were formed.The composite particles prepared by SA-Man-PEI and OVA showed good storage stability at 37℃and 4℃.According to the in vivo immune experiment and macrophage phagocytosis experiment of BALB/c mice,SA-Man-PEI can significantly enhance the specific immune response to OVA and promote the endocytosis of macrophages compared with Man-PEI and SA-PEI.An alternative cationic polymer adjuvant is provided for vaccines.