Ultrasmall Graphene Oxide Supported Gold Nanoparticles as Adjuvants Improve Humoral and Cellular Immunity in Mice

Adjuvants play an important role in vaccines. Alum and MF59 are two dominant kinds of adjuvants used in humans. Both of them, however, have limited capacity to generate the cellular immune response required for vaccines against cancers and viral diseases. It is desirable to develop new and efficient adjuvants with the aim of improving the cellular immune response against the antigen. Here, the feasibility and efficiency of ultrasmall graphene oxide supported gold nanoparticles (usGO‐Au) as a new immune adjuvant to improve immune responses are explored. usGO‐Au is obtained from reduction of chloroauric acid using usGO and then decorated with ovalbumin (OVA, a model antigen) through physical adsorption to construct usGO‐Au@OVA. As the results show, the as‐synthesized usGO‐Au@OVA can efficiently stimulate RAW264.7 cells to secrete tumor necrosis factor‐α (TNF‐α), a mediator for cellular immune response. In vivo studies demonstrate that usGO‐Au@OVA can also promote robust OVA specific antibody response, CD8⁺ T cells proliferation, and different cytokines secretion. The results indicate that using usGO‐Au as an adjuvant can stimulate potent humoral and cellular immune responses against antigens, which may promote better understanding of cellular immune response and facilitate potential applications for cancer and viral vaccines.