title: Generic methods for micrometer- and nanometer-scale surface derivatization based on photochemical coupling of primary amines to monolayers of aryl azides on gold and aluminum oxide surfaces.
abstract: A series of aryl azide terminated thiols and phosphonic acids has been synthesized, and used to prepare self-assembled monolayers on (respectively) gold and aluminum oxide surfaces. The rates of photoactivation were determined using contact angle measurement and X-ray photoelectron spectroscopy (XPS). The behavior of a diazirine functionalized aryl thiol was also studied. The rates of activation were found to be similar for all five adsorbates. However, the extent of photochemical coupling of a primary amine was significantly greater for the aryl azides than for the diazirine. A range of primary amines was successfully coupled to all of the azides with high yield. Little difference in reactivity was observed following perfluorination of the aromatic ring. Micrometer-scale patterns were fabricated by carrying out exposures of the aryl azide terminated SAMs through a mask submerged under a film of primary amine. Contrasting amines could be introduced to unreacted regions in a subsequent maskless step. A scanning near-field optical microscope was used to fabricate nanopatterns. Exposure of the azides to irradiation at 325 nm in air enabled selective deactivation of azides. The surrounding surface was functionalized with a primary amine in a maskless process; when a protein-resistant oligo(ethylene glycol) functionalized amine was used it was possible to produce protein nanopatterns, by adsorbing protein to features defined using near-field exposure.
authors.affiliation: Department of Chemistry, University of Sheffield, Brook Hill, Sheffield S3 7HF, UK.
authors.forename: Osama
authors.initials: O
authors.lastname: El Zubir
authors.forename: Iain
authors.initials: I
authors.lastname: Barlow
authors.forename: Ehtsham
authors.initials: E
authors.lastname: Ul-Haq
authors.forename: Hairul A
authors.initials: HA
authors.lastname: Tajuddin
authors.forename: Nicholas H
authors.initials: NH
authors.lastname: Williams
authors.forename: Graham J
authors.initials: GJ
authors.lastname: Leggett