The photocatalytic properties of titania are well-documented: absorption of UV photons causes oxidative degradation of organic molecules in close proximity to the oxide surface. Here we report the exploitation of this phenomenon for nanofabrication.First, self-assembled monolayers (SAMs) of alkylphosphonates on the native oxide of a titanium film are used as a resist for exposure in a Lloyd's Mirror interferometer. Exposure to maxima in the interferogram causes selective photocatalytic degradation of the SAM and etching in piranha solution causes dissolution of the oxide and underlying metal in the exposed areas, yielding line widths as good as 22 nm with a variable but controllable period ?/2sin?. Interferometric lithography offers fast, simple, inexpensive routes to nanofabrication over macroscopic areas (cm2). Second, features imprinted in a spin-case film of titanium methacrylate monomer are cured then calcined to yield titanium nanostructures. For both methods, the native oxide at the surface of the Ti structures exhibits photocatalytic activity and is used to control protein adsorption.Adsorption of an amine terminated alkyl phosphonate onto the titania nanostructures enables their functionalization with proteins, while adsorption of an oligo(ethylene glycol) terminated silane (OEG-silane) onto the substrate surface (silica) between the structures renders it protein-resistant. Alternatively, the entire sample is functionalized by adsorption of OEG-silane, and the titania regions rendered adhesive to proteins by irradiation by flooding the sample with near-UV light to cause photocatalytic removal of the OEG-silane from the Ti structures. In both cases, the proteins are completely removed by photocatalytic degradation via subsequent irradiation of the surface at 325 nm, while the OEG-silane adsorbed on silica remains intact. The titania regions may be functionalized using a different protein. The process may be repeated many times, offering a simple methodology for the presentation of nanostructured assemblies at surfaces over macroscopic areas.

Self-cleaning, reusable templates for protein nanopatterning fabricated by interferometric lithography and nanoimprinting

248th National Meeting (2014)

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