title: Novel ultrathin poly(ethylene glycol) films as flexible platform for biological applications and plasmonics.
abstract: We present a novel approach to prepare ultrathin, biocompatible films based on cross-linking of multi-functionalized, star-branched poly(ethylene glycols) (STAR-PEGs) with tunable film thicknesses of 4-200 nm. A two-component mixture of amine- and epoxy-terminated four-arm STAR-PEGs (MN=2000 g/mol) was spin-coated on a flat substrate. Gentle heating induced an extensive chemical cross-linking of the macromonomers, resulting in a stable, hydrogel-like film with a density close to that of bulk PEG material. The cross-linking process could be monitored in situ, exhibiting the expected kinetics. The films revealed pronounced swelling behavior, which was fully reversible and could be precisely controlled. Additionally, they provided a high affinity to citrate-stabilized gold nanoparticles (AuNP) that could be adsorbed with high densities into the PEG matrix from an aqueous solution. These novel PEG/AuNP composite films offer interesting and potentially useful optical properties. The adsorption could also be performed in a lithographic fashion, resulting in AuNP patterns imbedded into the PEG matrix.
authors.affiliation: Angewandte Physikalische Chemie, Universität Heidelberg, 69120 Heidelberg, Germany.
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Meyerbröker
authors.forename: Thomas
authors.initials: T
authors.lastname: Kriesche
authors.forename: Michael
authors.initials: M
authors.lastname: Zharnikov
mesh_terms: D006046:Gold / Q000737:chemistry; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D056951:Photoelectron Spectroscopy; D011092:Polyethylene Glycols / Q000737:chemistry*; D013696:Temperature
chemical_list: D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D011092:Polyethylene Glycols; D006046:Gold