Electrochemical Modification of Nanoparticles: Melanin-iron Covered Gold Nanoparticles.

D. GRUMELLI; C. VERICAT; G. BENITEZ; R.C. SALVAREZZA; RAMALLO-LÓPEZ, J. M.; GIOVANETTI, L. J.; REQUEJO, F.G.; Y.S. SHON; A. GONZÁLEZ ORIVE; Y. GIMENO; A. HERNÁNDEZ CREUS

Sevilla, España

Congreso; 59th Annual Meeting of the International Society of Electrochemistry; 2008

Thiol-capped and thiol free gold nanoparticles (AuNPs) 2.7 nm in size spontaneously adsorbed on HOPG have been used as substrates for deposition of melanin-iron shells by electrochemical methods. The melanin-iron coated AuNPs were characterized by XPS, EXAFS, XANES, SAXS, STM, and UV spectroscopy. Direct deposition on the thiol-capped AuNPs decreases the shell thickness with respect to that formed on thiol-free AuNPs. Thiol electrodesorption results in the delivery of a significant amount of melanin-iron coated AuNPs from the HOPG surface to the electrolyte solution. UV spectra of the solutions and XPS data show that NPs preferentially select dihydroxyindole species or small oligomers from the complex polymer during the electrochemical deposition of melanin. This strategy, which integrates electrochemistry and nanotechnology, could be applied to the preparation of efficient Fe-containing organic catalysts for electrically stimulated delivery devices, in analytical separations, in biosensors, and in nanometer sized magnetic storage devices, among others.