The Research On The Immune Adjuvant Effects Of Mesoporous Hydroxylapatite And Fluorescent Carbon Dots

OBJECTIVES: To study the immunological effects of mesoporous hydroxyapatite and fluorescent carbon dots as immune adjuvant,and to provide a systematic basis for the design of new immune adjuvant.METHODS: The mesoporous hydroxyapatite was synthesized by hydrothermal method using chitosan calcium carbonate as template,and the physical and chemical properties were characterized.The Balb/c mice were injected subcutaneously with the model vaccine composed of mesoporous hydroxyapatite and ovalbumin.After the immunization,the immune effect was tested by relevant immunoassay.The fluorescent carbon dots were synthesized by chitosan and bPEI25 k as the carbon source,and the physical and chemical properties were characterized.The Balb/c mice were immunized intranasally with the model vaccine composed of fluorescent carbon dots and ovalbumin.After the immunization,the immune effect was tested by relevant immunoassay.RESULTS: The synthesized mesoporous hydroxyapatite was about 2-3 ?m in size and about 50 nm in pore size.It had low cytotoxicity and could adsorb OVA antigen in a large amount,and the adsorption rate was as high as 36%.Mesoporous hydroxyapatite enhances dendritic cell activation,promotes lymphocyte proliferation and differentiation,produces higher levels of cytokines,enhances the secretion of specific IgG antibodies and produces more memory T cells,so that the body produces more effective and stronger specific immune response.The synthesized fluorescent carbon dots were nano-sized and positively charged with a large amount of hydroxyl and amino groups on its surface.It was capable of absorbing ultraviolet light,and emissing fluorescence upon excitation.Fluorescent carbon dots could prolong the action time of antigen,promote lymphocyte proliferation and differentiation,produce higher levels of cytokines,increase the secretion of specific IgG antibodies and specific IgA antibodies and produce more memory T cells,so that the body produces more potent and more effective specific systemic immune response and specific local mucosal immune response.CONCLUSIONS: Mesoporous hydroxyapatite exhibits good immunoadjuvant effects as immunization adjuvant of traditional injectional vaccines,and the fluorescent carbon dots have excellent immunological adjuvant properties as mucosal vaccine immunoadjuvant.This study has laid a solid foundation for the design of new immune adjuvant.