title: Carboxy-terminated oligo(ethylene glycol)-alkane phosphate: synthesis and self-assembly on titanium oxide surfaces.
abstract: The surface immobilization of oligo- and poly(ethylene glycol) on solids is a widely used approach to prevent the nonspecific adsorption of proteins, bacteria, and cells. A novel tri(ethylene glycol) derivative, phosphoric acid-mono(22-carboxy-12,15,18,21-tetraoxadocosyl) ester, was synthesized with the aim to produce self-assembled monolayers (SAMs) on metal/metal oxide surfaces. This compound contains two reactive, terminal moieties: the phosphoric acid group as anchor to the surface, and the carboxylic group as linker for further attachment of molecules such as peptides and proteins to be present at the surface. The adsorption on titanium-dioxide-coated substrates was studied quantitatively and the resulting SAMs were characterized by angle-dependent X-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry. XPS data showed that the monomolecular layer is attached with the phosphate group to the substrate, but not fully ordered. The dry adlayer thickness was determined to be 13.4 A, which is less than expected for a densely packed monolayer. Surface concentration calculated from ellipsometry data resulted in a grafting density of 2.03 molecules/nm2.
authors.affiliation: Institute for Macromolecular Chemistry and Textile Chemistry, Department of Chemistry and Food Chemistry, Faculty of Science, Technische Universität Dresden, Dresden, Germany.
authors.forename: Mandy
authors.initials: M
authors.lastname: Gnauck
authors.forename: Evelin
authors.initials: E
authors.lastname: Jaehne
authors.forename: Thomas
authors.initials: T
authors.lastname: Blaettler
authors.forename: Samuele
authors.initials: S
authors.lastname: Tosatti
authors.forename: Marcus
authors.initials: M
authors.lastname: Textor
authors.forename: Hans-Juergen P
authors.initials: HJ
authors.lastname: Adler
mesh_terms: D000327:Adsorption; D000473:Alkanes / Q000737:chemistry; D002264:Carboxylic Acids / Q000737:chemistry; D004577:Electron Probe Microanalysis / Q000379:methods; D007700:Kinetics; D008956:Models, Chemical; D009943:Organophosphorus Compounds / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry; D010710:Phosphates / Q000737:chemistry*; D010756:Phosphoric Acids / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D013379:Substrate Specificity; D013499:Surface Properties; D013997:Time Factors; D014025:Titanium / Q000737:chemistry*
chemical_list: D000473:Alkanes; D002264:Carboxylic Acids; D009943:Organophosphorus Compounds; D010455:Peptides; D010710:Phosphates; D010756:Phosphoric Acids; C009495:titanium dioxide; D011092:Polyethylene Glycols; D014025:Titanium; C030242:phosphoric acid