HNMs have been also applied to the delivery of antigens, exposing them to the immune system. Fullerenes were found as suitable carriers for the delivery of drugs or nucleic acids.138 Functionalized fullerene can also self-assemble into virus-sized NPs.139 Investigated as vaccines in cancer immune therapy,140 polyhydroxy fullerenes (called fullerenols) display interesting properties for antiviral therapy, based on their capacity to self-assemble into virus-like particles (VLPs) and so to enhance the immunogenicity of the antigens.141 The great advantage of this strategy relies on the easy encapsulation process during the self-assembly making fullerenols versatile for the formulation of different kinds of vaccines. These VLPs were investigated against HIV-1141 and hepatitis C viruses.142 Compared to conventional protein- or peptide-based vaccines intended to induce antigen-specific adaptive immune responses, DNA vaccines are more stable, cost-effective, easy to manufacture, and safe in handling.143 However, DNA vaccines have the disadvantage of being poorly immunogenic.144 Fullerenol VLPs allow to avoid the use of other adjuvants. In the case of a vaccine against HIV-1, fullerenol VLPs penetrated easily into the cells resulting in an enhancement of DNA transfection. This was proved in a study using fullerenol encapsulating DNA encoding the HIV-1 envelope protein gp145 (Figure 17).141In vitro assays were performed in human embryonic kidney cells line (HEK293) showing good transfection ability. Following various immunization routes (e.g., activation of Toll-like receptor signaling or effector memory T cell immune response), fullerenol VLPs can induce an innate and a cellular immunity. A similar study was performed for hepatitis C using the HCV recombinant protein as antigen,142 confirming the potential efficacy of using fullerenols as antiviral vaccines. Nevertheless, these results require further mechanistic investigations. Indeed, in vitro studies also evidenced a suppressive effect of acquired immune response of C60 pyrrolidine tris-acid and fullerenol C60(OH)36.145 The fullerenol had a dose-dependent effect on T cell receptor-mediated activation and antibody production by B cells under anti-CD40/IL-4 stimulation. However, the molecular mechanism is still unknown.