AVS 55th International Symposium & Exhibition
    Biomaterial Interfaces Thursday Sessions
       Session BI-ThP

Paper BI-ThP6
A Simple Method for Making Highly Ordered Chemical Patterns by Sputtering Through Ordered Binary Colloidal Crystals

Thursday, October 23, 2008, 6:00 pm, Room Hall D

Session: Biomaterial Interfaces Poster Session with Focus on Engineered Bio-Interfaces and Sensors
Presenter: P. Kingshott, The University of Aarhus, Denmark
Authors: G. Singh, The University of Aarhus, Denmark
V. Gohri, The University of Aarhus, Denmark
S. Pillai, The University of Aarhus, Denmark
A. Arpanaei, The University of Aarhus, Denmark
M. Foss, The University of Aarhus, Denmark
P. Kingshott, The University of Aarhus, Denmark
Correspondent: Click to Email

Nanopatterning of biomolecules, such proteins, DNA, and polysaccharides are of great interest in cell culture dishes, biosensors, medical implants and tissue engineering. These so-called nanoarrays require attachment of biomolecules at specific locations on solid substrates with precisely controlled chemistry, but to function fully the non-specific adsorption in surrounding regions must be prevented. Currently, the most widely used techniques for patterning are photolithography, soft lithography, or dip-pen AFM lithography, all of which involve multi-step surface modification directly onto substrates, and are time consuming and expensive. We have shown recently that highly ordered binary polystyrene nanoparticle patterns can be generated from simple self-assembly onto surfaces, where single layers of large particles are surrounded by crystals of smaller particles. Here, we report a novel method for generating chemical nanopatterns by Au sputtering through the crystal layer followed by lift-off of the particles. The crystal regions of the binary pattern, composed of the smaller particles, facilitate transport of the Au sputter beam to the substrate. After particle lift-off only the regions where the small particles have been in contact with the silicon substrate are coated with Au. The large particles act as a mask and remain uncoated, and the thickness of the surrounding Au layer is controlled by the sputter time. The highly ordered chemical patterns are generated where the size of the features are tuned by appropriate choice of particle sizes (50nm to 3µm diameters) and ratios. The stability of the Au layers to aqueous environments is ensured by coating the Si wafer with a thiolated silane, which acts as an adhesion layer. We demonstrate that the resultant Au layer can be coated with a protein resistant mercapto-oligo(ethylene glycol) layer ((1-mercapto-11-undecyl)-tri(ethylene glycol)) that allows selective adsorption of fluorescently labelled proteins on to the Si regions of the pattern. The Au patterns and subsequent protein adsorption are characterized by AFM, SEM and fluorescent microscopy. XPS and ToF-SIMS are used to characterise the chemical modification steps of the patterning. In summary, we introduce a novel method for generating highly-ordered chemical nanopatterns that is very fast, inexpensive, and allows patterns of biomolecules to be created over large areas.