Patterned and switchable surfaces for biomaterial applications

Andrew Hook – Patterned and switchable surfaces for biomaterial applicationsaccessible to life science laboratories, and whilst soft lithography has been adoptedby life science researchers for surface patterning, methods such as microcontactprinting or micromolding are not conducive to the production of an array ofchemically or biologically diverse spots. Moreover, additional deposition ofbiomolecular arrays on top of the cell growth regulating patterns would typicallyoccur in a different instrument, e.g. a microarray printer, such that pattern alignmentissues arise and have to be overcome (see section 2.3.4) [174].Here, the formation of a chemical pattern using photoreactive polymers isreported. Photoreactive crosslinkers have previously been investigated for covalentlyimmobilising peptides, proteins and other biomolecules for the formation ofbiomolecular microarrays [220]. Typically, the underlying surface chemistry can bemodified to contain photoactivatable groups that upon irradiation with a light sourceproduce a highly reactive functional group that readily forms covalent bonds withbiomolecules printed onto the layer [220]. This approach has been utilised to altersurface chemistry by immobilising polymer molecules to a surface [221], however,this is limited to surface coatings that can be functionalised, which may present aconflicting requirement to that of low fouling properties and also requires a blockingstep in order to prevent binding to unreacted sites. Alternatively, the biomoleculesthemselves can be modified to contain a photoactivatable group. Peptides containingthe Arg-Gly-Asp sequence have been immobilised to a surface by this method inorder to promote cell attachment [222]. Furthermore, stable polymer surface coatingshave been generated by functionalising a polymer of interest with a photoactivatablegroup [223]. This approach has also been adapted for modifying the surface ofnanoparticles [224]. By utilising robotic contact printing, this approach could easilybe adapted for development of a patterned substrate for formation of a cell4-131