title: Fabrication of Self-Cleaning, Reusable Titania Templates for Nanometer and Micrometer Scale Protein Patterning.
abstract: The photocatalytic self-cleaning characteristics of titania facilitate the fabrication of reuseable templates for protein nanopatterning. Titania nanostructures were fabricated over square centimeter areas by interferometric lithography (IL) and nanoimprint lithography (NIL). With the use of a Lloyd's mirror two-beam interferometer, self-assembled monolayers of alkylphosphonates adsorbed on the native oxide of a Ti film were patterned by photocatalytic nanolithography. In regions exposed to a maximum in the interferogram, the monolayer was removed by photocatalytic oxidation. In regions exposed to an intensity minimum, the monolayer remained intact. After exposure, the sample was etched in piranha solution to yield Ti nanostructures with widths as small as 30 nm. NIL was performed by using a silicon stamp to imprint a spin-cast film of titanium dioxide resin; after calcination and reactive ion etching, TiO2 nanopillars were formed. For both fabrication techniques, subsequent adsorption of an oligo(ethylene glycol) functionalized trichlorosilane yielded an entirely passive, protein-resistant surface. Near-UV exposure caused removal of this protein-resistant film from the titania regions by photocatalytic degradation, leaving the passivating silane film intact on the silicon dioxide regions. Proteins labeled with fluorescent dyes were adsorbed to the titanium dioxide regions, yielding nanopatterns with bright fluorescence. Subsequent near-UV irradiation of the samples removed the protein from the titanium dioxide nanostructures by photocatalytic degradation facilitating the adsorption of a different protein. The process was repeated multiple times. These simple methods appear to yield durable, reuseable samples that may be of value to laboratories that require nanostructured biological interfaces but do not have access to the infrastructure required for nanofabrication.
authors.affiliation: †Department of Chemistry, University of Sheffield, Sheffield S3 7HF, United Kingdom.|‡Institute of Materials Research and Engineering (IMRE), A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602, Republic of Singapore.
authors.forename: Mark
authors.initials: M
authors.lastname: Moxey
authors.affiliation: †Department of Chemistry, University of Sheffield, Sheffield S3 7HF, United Kingdom.
authors.forename: Alexander
authors.initials: A
authors.lastname: Johnson
authors.affiliation: †Department of Chemistry, University of Sheffield, Sheffield S3 7HF, United Kingdom.
authors.forename: Osama
authors.initials: O
authors.lastname: El-Zubir
authors.affiliation: §Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom.
authors.forename: Michael
authors.initials: M
authors.lastname: Cartron
authors.affiliation: ‡Institute of Materials Research and Engineering (IMRE), A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602, Republic of Singapore.
authors.forename: Saman Safari
authors.initials: SS
authors.lastname: Dinachali
authors.affiliation: §Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom.
authors.forename: C Neil
authors.initials: CN
authors.lastname: Hunter
authors.affiliation: ‡Institute of Materials Research and Engineering (IMRE), A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602, Republic of Singapore.
authors.forename: Mohammad S M
authors.initials: MS
authors.lastname: Saifullah
authors.affiliation: ‡Institute of Materials Research and Engineering (IMRE), A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602, Republic of Singapore.
authors.forename: Karen S L
authors.initials: KS
authors.lastname: Chong
authors.affiliation: †Department of Chemistry, University of Sheffield, Sheffield S3 7HF, United Kingdom.
authors.forename: Graham J
authors.initials: GJ
authors.lastname: Leggett
mesh_terms: D049329:Nanostructures / Q000737:chemistry*; D036103:Nanotechnology; D011506:Proteins / Q000032:analysis* / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*
chemical_list: D011506:Proteins; C009495:titanium dioxide; D014025:Titanium
keywords: interferometric lithography; nanofabrication; nanoimprint lithography; photocatalysis; photolithography; protein arrays; titania