Active immobilization of biomolecules on a hybrid three-dimensional nanoelectrode bydielectrophoresis for single-biomolecule study

Abstract

We propose and experimentally demonstrate a method of active immobilization forbiomolecules on a three-dimensional nanometre-scale electrode (3D nanoelectrode) usingdielectrophoresis to immobilize the biomolecules at predetermined locations forsingle-biomolecule study. We have developed a novel two-step fabrication process forobtaining a 3D nanoelectrode having a sharp top, which is necessary for immobilizing asingle biomolecule at a single point. The first step is to fabricate the backbonestructure, which is rigid and defines the shape of the 3D nanoelectrode. It wasfabricated with diamond-like carbon (DLC) obtained using focused ion beam assistedchemical vapour deposition followed by post-plasma etching, which reshapes the DLCstructure. The second step coats the DLC structure with a thin layer of aluminium,which supplies electrical conductivity to the DLC structure. By applying a highfrequency (of the order of megahertz) and high intensity (greater than or equalto a few megavolts per metre) electric field using the 3D nanoelectrodes, thegenerated dielectrophoresis attracted and then immobilized target biomolecules ontothe tops of 3D nanoelectrodes, as a demonstration of active immobilization ofbiomolecules.