Interaction of metallic nanoparticles with a biologically active molecule, dopamine.

We present the results of first-principles molecular orbital calculations describing the interaction of metallic nanoparticles, represented by Mn(13), Ag(13), and Al(13) atomic clusters, with a biologically active molecule, dopamine. The interaction strength, determined in terms of the nanoparticle-molecule complex binding energy, is found to be higher for Mn than either Ag or Al and can be explained in terms of the degree of the hybridization of the (metal) atomic orbitals with the molecular orbitals in the complex. Furthermore, smaller interaction strength of these metallic nanoparticles with water compared to that with dopamine predicts the preference of forming a complex of dopamine with the metallic nanoparticles in the aqueous solution. The calculated results may therefore suggest that the presence of these metallic nanoparticles could induce different levels of dopamine depletion in solution.