Immobilization of horseradish peroxidase via an amino silane on oxidized ultrananocrystalline diamond

We discuss the complete functionalization of nitrogen-doped ultrananocrystalline diamond (UNCD) films, starting from an oxidized surface. First, the presence of hydroxyl groups on oxidized nanocrystalline diamond (NCD) was confirmed by fluorescence microscopy. Next, the grafting of a linker molecule such as 3-aminopropylmethyldiethoxysilane on oxidized NCD was confirmed by fluorescence microscopy and X-ray photoelectron spectroscopy (XPS). Then the horseradish peroxidase (HRP) enzyme was immobilized on silane-modified initially oxidized UNCD. The HRP-modified UNCD was characterized by electrochemical techniques, such as faradaic cyclic voltammetry and the amperometric response to H2O2. This response to H2O2 is discussed in terms of the layer-by-layer configuration used and the electronic properties of conducting UNCD.