Molecular and biomolecular interfaces to metal oxide semiconductors

Abstract

Previous work has shown that organic alkenes will graft to covalent semiconductors such as diamond and silicon. Here, we demonstrate that organic alkenes can be grafted to the surfaces of metal oxide semiconductors, including TiO2 in nanocrystalline thin films and as single‐crystal anatase(001) epitaxial films grown on SrTiO3(001) substrates. The resulting layers can be used as a starting point for linking biomolecules such as DNA to metal oxide surfaces. Initial results are presented showing that this chemistry can also be applied to graft molecular layers to zirconium oxide thin films. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Biofunctionalization of a “Clickable” Organic Layer Photochemically Grafted on Titanium Substrates

“…Analysis of the high-resolution spectra of Ti 2p (Figure 1b) indicates that Ti element on the surface was mainly in Ti 4+ –O form, showing two major spin–orbit components unique to TiO 2 at about 458.2 and 464.2 eV, respectively. 22–24 In Figure 1, the main contribution of O 1s (binding energy 530.1 eV) originates from the oxygen in the TiO 2 substrate. 34 The shoulder peak near 531.5 eV is similar to those reported previously from physisorbed water, oxidized carbon species, and partially hydroxylated TiO 2 .…”

“…22–24 A set of control experiments was performed to test whether it was necessary to protect the alkyne by TMG group during the photochemical grafting (see Supporting Information, Figure S1). The results showed that if the vinyl group in TMG-C10 was replaced by an ethynyl group, the molecule could also attach on the TiO 2 substrate under identical irradiation conditions.…”

“…22–24 Although the exact mechanism of the reaction remains unclear, the formed organic layer was chemically and thermally very stable in electrolyte solutions, thus showing great potential in the field of biomedical application. However, the photografting condition, which involves extended exposure to 254 nm UV light, does not allow direct immobilization of many bioactive molecules.…”

“…For example, Hamers and co-workers employ trifluoroacetyl protected amine as a precursor to amine-terminated surfaces that were useful for subsequent modification with DNA or proteins. 23,24 However, harsh reaction was required for the deprotection of the trifluoroacetyl group to expose the amine functionality.…”

Kovalente Oberflächenmodifikationen von Oxiden

“…Analoge photochemische Reaktionen wurden auf ZnO(1010)‐Einkristallen und ZnO‐Nanostäbchen,141 Zirconiumoxid,142 dünnen Filmen aus SnO 2 ‐Nanopartikeln143 und GaN beobachtet 144. Im letztgenannten Fall binden die Moleküle, wie in Abbildung 40 gezeigt, über eine Ga‐O‐C‐Brücke an die GaN‐Oberfläche.…”