A method and apparatus is utilized for producing colloidal dispersions of
nanoparticles of electrically conducting materials. The colloidal
dispersions are produced in a dense media plasma reactor comprising at
least one static electrode and at least one rotating electrode. The
plasma reaction sputters off minute particles of the electrically
conducting material from which the electrodes are made. Methods of using
the colloidal dispersions thus made are also described. Colloidal
dispersions of silver produced in this manner are highly effective for
bactericidal purposes.