title: Glass surfaces grafted with high-density poly(ethylene glycol) as substrates for DNA oligonucleotide microarrays.
abstract: Surfaces carrying a dense layer of poly(ethylene glycol) (PEG) were prepared, characterized, and tested as substrates for DNA oligonucleotide microarrays. PEG bis(amine) with a molecular weight of 2000 was grafted onto silanized glass slides bearing aldehyde groups. After grafting, the terminal amino groups of the PEG layer were derivatized with the heterobifunctional cross-linker succinimidyl 4-[p-maleimidophenyl]butyrate to permit the immobilization of thiol-modified DNA oligonucleotides. The stepwise chemical modification was validated with X-ray photoelectron spectroscopy. Goniometry indicated that the PEG grafting procedure reduced surface inhomogeneities present after the silanization step, while atomic force microscopy and ellipsometry confirmed that the PEG layer was dense and monomolecular. Hybridization assays using DNA oligonucleotides and fluorescence imaging showed that PEG grafting improved the yield in hybridization 4-fold compared to non-PEGylated maleimide-derivatized surfaces. In addition, the PEG layer reduced the nonspecific adsorption of DNA by a factor of up to 13, demonstrating that surfaces with a dense PEG layer represent suitable substrates for DNA oligonucleotide microarrays.
authors.affiliation: Center for Biomedical Nanotechnology, Upper Austrian Research GmbH, A-4020 Linz, Austria.
authors.forename: Robert
authors.initials: R
authors.lastname: Schlapak
authors.forename: Patrick
authors.initials: P
authors.lastname: Pammer
authors.forename: David
authors.initials: D
authors.lastname: Armitage
authors.forename: Rong
authors.initials: R
authors.lastname: Zhu
authors.forename: Peter
authors.initials: P
authors.lastname: Hinterdorfer
authors.forename: Matthias
authors.initials: M
authors.lastname: Vaupel
authors.forename: Thomas
authors.initials: T
authors.lastname: Frühwirth
authors.forename: Stefan
authors.initials: S
authors.lastname: Howorka
mesh_terms: D020099:Coated Materials, Biocompatible; D005898:Glass; D008422:Materials Testing; D018625:Microscopy, Atomic Force; D020411:Oligonucleotide Array Sequence Analysis / Q000295:instrumentation*; D011092:Polyethylene Glycols; D013057:Spectrum Analysis; D014965:X-Rays
chemical_list: D020099:Coated Materials, Biocompatible; D011092:Polyethylene Glycols