Novel metal-lipid molecules have the formula M--Or--L. M represents a cluster or colloid of atoms of Au, Ag, Pt, Pd, or combinations thereof. Or is an organic group covalently attached to the metal atoms. L represents a lipid moiety. In a preferred embodiment, M represents a cluster of about 50-70 gold atoms having a diameter of about 1.4 nm in diameter and L represents dipalmitoyl phosphatidyl ethanolamine.