Bio-inspired catechol chemistry for electrophoretic nanotechnology of oxide films.

Bio-inspired chemical approach has been developed for the surface modification and electrophoretic deposition of manganese dioxide and zirconia nanoparticles, prepared by chemical precipitation methods. Caffeic acid, trans-cinnamic acid, p-coumaric acid, and 2,4-dihydroxycinnamic acid were investigated for the surface modification of the nanoparticles. The influence of the structure of the organic molecules on their adsorption on the oxide nanoparticles has been investigated. The mechanism of caffeic acid adsorption was similar to that of natural catecholic amino acid, L-3,4-dihydroxyphenylalanine. The use of caffeic acid allowed for agglomerate-free synthesis, efficient dispersion, charging, electrophoretic deposition and co-deposition of manganese dioxide and zirconia nanoparticles. The deposition yield data, coupled with the results of thermogravimetric analysis, X-ray diffraction analysis, and Fourier transform infrared spectroscopy, showed that surface chemistry, rather than the crystal structure, determined the adsorption behavior. Electron microscopy and energy dispersive spectroscopy investigations showed the formation of nanostructured oxide films and composites. The deposit composition can be varied.