Selective Deposition of Lipid Membranes on Locally Anodic-Oxidized Silicon Surface

Abstract

We demonstrate control of biomolecule adsorption on Si oxide islands formed by local anodic oxidation using atomic force microscopy. Local anodic oxidation was performed on a thin-SiO2/Si substrate covered with an octadecyltrimethoxysilane (OTMS) film. Dipalmitoylphosphatidylcholine (DPPC) molecules were deposited on the oxide islands. Hydrophilicity of the oxide island surfaces decreased with an increase in the applied voltage. When high voltages were applied, the oxide islands laterally expanded to form round shape and more hydrophilic oxide areas formed in the periphery of the islands. Density of OH groups on the anodic oxide island surface, which determines the surface hydrophilicity, is changed by the applied voltage during the oxidation. Since lipid membrane formation is strongly affected by surface hydrophilicity, selective deposition of DPPC membranes was achieved. We concluded that local anodic oxidation is a useful method for controlling biomolecule adsorption through oxide surfaces with variable hydrophilicity. [DOI: 10.1380/ejssnt.2011.357]