Nano vaccines operate by encapsulating antigens within nanoparticles, which can be made from various materials such as lipids, polymers, or proteins. These nanoparticles protect the antigens from degradation and facilitate their delivery to immune cells. Upon administration, the nanoparticles are taken up by dendritic cells or other antigen-presenting cells, which then process and present the antigens to T cells, initiating an immune response.