| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2014) | |
| Nanomaterials | Monday Sessions |
| Session NM-MoM |
| Session: | Nano Fabrication |
| Presenter: | David Williams, The University of Auckland, New Zealand |
| Authors: | DE. Williams, The University of Auckland, New Zealand Malstrom, The University of Auckland, New Zealand Wason, The University of Auckland, New Zealand Papst, The University of Auckland, New Zealand Roache, The University of Auckland, New Zealand Strover, The University of Auckland, New Zealand Hackett, The University of Auckland, New Zealand Pei, The University of Auckland, New Zealand Leung, The University of Auckland, New Zealand Brimble, The University of Auckland, New Zealand Evans, The University of Auckland, New Zealand Travas-Sejdic, The University of Auckland, New Zealand Gerrard, The University of Auckland, New Zealand |
| Correspondent: | Click to Email |
We have explored self-assembling proteins and block co-polymers, rationally designed peptides, and switchable polymer brushes as design elements for functional nanostructures.
Block co-polymers can self-assemble to form interesting regular nanostructures. Indeed, micro-phase separation in block copolymers has been fairly extensively explored as a means of patterning high-density memory elements. Similarly, proteins self-assemble: individual subunits can assemble into doughnuts, stacks, fibres and scaffolds. We have explored the idea of combining the two, using micro-phase separation of a block copolymer as a means to organise a protein stack which may then be used to organise something else. In the RNA-binding protein Lsm-α, monomeric subunits assemble into doughnuts. The doughnuts can then be induced to form stacks by a combination of protein engineering and changes in solution conditions such as pH and metal ion concentration. These nanoscale tunnels can then potentially acts as a template to organise metal ion or nanoparticle columns. In order to organise the protein stacks, we have explored the segregation of the protein into the hydrophilic domains of a hydrophobic-hydrophilic block copolymer. We illustrate the idea using thin films of poly(styrene)-b-poly(ethyleneoxide) – PS-b-PEO, with the Lsm-α doughnut incorporated into self-assembled hexagonally packed cylinders of PEO. The issues are choice of a solvent system that promotes structuring of the polymer, and functionalization of the protein to convey compatibility with the solvent system necessary for formation of the micro-phase separated structure, whilst still retaining the structure, function and organisation of the protein.
In a different approach to building up the elements needed to construct functional nanostructures, we have been exploring the use of rationally designed peptides as templates for nanoparticle growth, and surface-grafted polymer brushes as switchable sub-units. Peptides offer great flexibility in molecular design. We have been able successfully to incorporate, in defined spatial organisation, sites that specifically adsorb to metal surfaces, sites that control inter-particle interaction, and sites that complex the particle precursor species and thus control particle nucleation. Separately, we have been able to synthesise co-polymer brush systems that are electrochemically switchable. We present initial approaches towards integrating all these structural and functional elements and studying their interaction with living cells.