Study on electrochemical deposition of organic molecules and surface modification of organic film on ITO

Abstract

The formation of thin film with different organic adsorbates on a substrate is increasingly important in designing functional surfaces such as biochip and molecular electronic devices. Especially, electrochemical deposition of functional molecules provides a simple and useful pathway to prepare the surfaces. To make functional surface, we performed electrochemically-induced deposition of MDAHQ (12,12``-dithiobis (dodecanoic acid hydroquinone monoester)) on indium-tin-oxide (ITO) glass. For the deposition, an anodic potential was applied on the electrochemical cell by cyclic voltammetric scans featuring gradual decrease of irreversible oxidation peaks. Thin film formation by the deposition was confirmed by using grazing angle FT-IR, X-ray photoelectron spectroscopy (XPS), and Atomic force microscopy (AFM). In addition, we revealed that disulfide group in the film could be reduced to free thiol form by electrochemical treatments. The reduction was confirmed by comparison of the results from chemical reduction with TCEP (Tris(2-carboxyethyl)phosphine hydrochloride). We demonstrated that the resulting thiol surface was used for an active site for the maleimide binding and gold nanoparticle immobilizing. This result will be applied to the micro or nanopatterning of various nanomaterials including biomolecules.