Biosensing properties of nanocrystalline diamond film grown on polycrystalline diamond electrodes

Micron-sized polycrystalline diamond electrode typically exhibits poor and sluggish response to ascorbic acid (L-AA) and cannot resolve voltammetrically mixtures of biomolecules (e.g. L-AA, dopamine (DA) and uric acid (UA)). This paper investigates a simple re-growth strategy to modify the polycrystalline diamond surfaces for making an active biosensing electrode. A thin, nominally undoped nanocrystalline diamond (NCD) layer has been grown on the surface of boron-doped polycrystalline diamond substrate using a high substrate bias voltage (-200 V) and a 12% hydrocarbon-in-hydrogen gas feed. We found that the over-potential for L-AA oxidation has been reduced from 400 to 60 mV and that voltammetric differentiation of DA and UA, or UA and L-AA, is possible on the NCD-modified diamond electrode. (c) 2004 Elsevier B.V. All rights reserved.