Laser interference pattern ablation of a carbon fiber microelectrode: Biosensor signal enhancement after enzyme attachment

Fluorescence microscopy was used to visualize the accumulated fluorescent p roduct of the enzyme alkaline phosphatase to indicate where active covalent ly bound enzyme remained on the surface after application of a Nd: YAG lase r interference pattern to a surface that was first globally derivatized wit h the covalently bound enzyme. The electrochemical. kinetics of the same ca rbon fiber surface were examined through the electrogenerated chemiluminesc ence of Ru(bpy)(3)(2+) to determine that electron-transfer sites were indee d segregated from the enzyme-binding sites. The enzyme-derivatized areas ar e determined to be separate and distinct from the areas of enhanced electro n transfer. The other enzymes, glucose oxidase and malic dehydrogenase, wer e then covalently bound to carbon fiber microelectrode surfaces in order to verify the change in detection limit of their respective cofactors, NADH o r H2O2, under a variety of surface conditions. The S/N of an enzgme-modifie d electrode after laser interference pattern photoablation and electrocatal ytic treatment is improved by more than 1 order of magnitude aver that obse rved at an electrode that is globally enzyme modified.