A LASER-ABLATION METHOD FOR THE SPATIAL SEGREGATION OF ENZYME AND REDOX SITES ON CARBON-FIBER MICROELECTRODES

A laser-generated interference pattern was used to remove enzyme from micrometer-wide stripes on an enzyme-covered carbon fiber microelectro de surface to create regions of facile electron transfer. Fluorescence microscopy was used to visualize fluorophore-tagged enzyme to indicat e where the adsorbed enzyme remained on the surface. The electrochemic al kinetics of the carbon fiber surface were examined to see if electr on-transfer. sites could indeed be segregated from enzyme adsorbed acr oss the entire surface. CCD imaging of the electrochemical luminescenc e of Ru(bpy)(3)(2+) was used to verify the segregation between photoab lated sites (with facile electron-transfer kinetics) and surfaces with adsorbed enzyme (which exhibit slow electron-transfer kinetics). The laser-ablated surface could also be distinguished from the enzyme-cove red carbon surface with atomic force microscopy. Thus, photoablation o f the surface of a protein-covered carbon fiber microelectrode with an interference pattern generated by a Nd:YAG laser allows the activatio n of 1.7-mu m-wide bands of the electrode surface (available for facil e electron transfer) while leaving 2.6-mu m-wide enzyme-modified areas intact, thereby producing electroactive regions directly adjacent to enzyme modified regions of the same surface.