Inhomogeneous DNA bonding to polycrystalline CVD diamond

Double stranded deoxyribonucleic acid (ds-DNA) layers, bonded to hydrogen terminated polycrystalline diamond, are characterized by scanning electron (SEM), fluorescence (FM), and atomic force microscopy (AFM). DNA grafting has been achieved using photochemical bonding of co-unsaturated 10-amino-dec-1-ene molecules. SEM detects local variations of electron affinities on polycrystalline diamond, revealing distinct grain structures. FM applied on fluorescence labeled ds-DNA show laterally varying intensities of typically 20%, which resembles also grain structure as detected by SEM. Contact and tapping-mode AFM characterization reveal a tilted DNA bonding to diamond and a dense layer formation which gives rise to smoothening of surface properties. The lateral density variation of DNA is attributed to local variations of the photoelectron emission efficiency which affects the photochemical attachment chemistry of amine-linker molecules to diamond. (c) 2007 Elsevier B.V All rights reserved.