Nanoparticulate formulation

A vaccine adjuvant comprising a plurality of nanoparticles that comprise an outer lipid shell and an inner aqueous core encapsulated within the outer lipid shell;

• wherein the inner aqueous core comprises an imidazoquinoline and a host molecule that is capable of reversibly forming a complex with the imidazoquinoline;
• wherein the imidazoquinoline is an active TLR7/8 ligand having the molecular structure
• where R1 is N and R2 is H or C, and where the imidazoquinoline is unsubstituted or is substituted at one or more of the indicated addition points with one or more substituents, which substituents are independently selected from branched, linear or cyclic alkyl, alkenyl, alcohol, alkylamine, alkoxy or alkoxyalkyl groups, in particular, C1-10 alkyl, alkenyl, alcohol, alkylamine, alkoxy or alkoxyalkyl groups, or hydroxyl groups, or amine groups, or N-(C1-10 alkyl)methanesulphonamide groups;
• and wherein the host molecule is a cyclodextrin.