An endotoxin nanovesicle for enhancing type 1 T helper cell-induced immunological responses is disclosed. The endotoxin nanovesicle comprises: (a) lipopolysaccharide molecules, assembled into a vesicle with a wall surrounding an inner space and (b) hydrophilic gold nanodots, localized in the wall of the vesicle. Methods of suppressing formation of cubosomes and/or hexosomes in lipopolysaccharide aggregation or assembly, and methods of preparing a lipopolysaccharide adjuvant are also disclosed. Also disclosed are compositions comprising an endotoxin aggregate or an endotoxin nanoversicle and optionally an immunogenic antigen.
