Graphene quantum dot-coated mesoporous silica loaded with glucosamine sulfate as a potent antigen delivery system for immunoactivation.

Graphene quantum dots (GQDs) belong to the carbon quantum dot family, with low toxicity, high biocompatibility, and excellent colloidal stability. Mesoporous silica nanoparticles (MSNs) are recognized as effective drug delivery systems due to their high drug-loading capacity, while glucosamine sulfate (GS) exhibits immunemodulatory properties. In this study, to maximize the immune effect of GS, a graphene quantum dot-coated mesoporous silica loaded with glucosamine sulfate (MSN-G-Q) is synthesized, and its immunoactivation effects are evaluated in vitro and in vivo. In vitro, MSN-G-Q enhances macrophage uptake activity, stimulates nitric oxide (NO) production, and upregulates CD80+ and CD86+ expression. In vivo, MSN-G-Q/OVA increases immune organ index, facilitates dendritic cell (DC) maturation, promotes T lymphocyte proliferation and differentiation, elevates antigen-specific IgG antibodies and cytokines, including IFN-γ, IL-4, and IL-1β, and prolongs ovalbumin (OVA) residence in immune organs and lymph nodes. The results show that MSN-G-Q/OVA is a promising immunostimulatory antigen delivery system.