Nanomaterials Assembly through Biomimetics
University of Washington, Materials Science and Engineering,
Seattle, WA 98195, USA
This is an abstract
for a presentation given at the
Foresight Conference on Molecular Nanotechnology.
There will be a link from here to the full article when it is
available on the web.
Many multicellular organisms produce hard tissues such as bones, teeth, shells, skeletal units, and spicules. These biocomposites incorporate both structural macromolecules (lipids, proteins, and polysaccharides) and minerals of, perhaps, 60 different kinds including hydroxyapatite, calcium carbonate, and silica. A number of single-celled organisms (bacteria and algae) also produce inorganic materials either intra- or extracellularly, such as magnetotactic bacteria and radiolarians. Normally hard tissues are mechanical devices (skeleton) or they serve a physical function (magnetic, optical, piezoelectric). The structures of biocomposites are highly controlled from the nanometer to the macroscopic levels, resulting in complex, hierarchical architectures that provide multifunctional properties that usually surpass those of analogous synthetically manufactured materials with similar phase compositions. Biological materials are assembled in aqueous environments under mild conditions using biomacromolecules that collect and transport raw materials, and consistently and uniformly self- and co-assemble subunits into short- and long-range ordered nuclei and substrates. Biological materials are simultaneously "smart", dynamic, complex, self-healing, and multifunctional, characteristics difficult to achieve in purely synthetic systems. Biomimetics, the use of biological principles in materials synthesis and assembly, may be a path for realizing nanotechnology, such as molecular and nanoscale electronics. 
Structural control and assembly of inorganic materials at the nanoscale is a key to the production of materials with new and improved properties. The intricate nano- and micro-architectures of biomaterials are controlled at the molecular level by proteins which have specific interactions with the mineral phase. Combinatorial genetic techniques permit isolation of specific recognition elements for surfaces, including those not recognized by natural proteins, in the absence of a priori prediction of necessary structures. Here we demonstrate controlled assembly of nanometer-scale gold particles on functionalized spherical and flat surfaces (resembling quantum dot structures) in aqueous solutions using engineered gold-binding proteins as recognition elements. Furthermore, using a newly-developed genetic system in the bacterium E. coli we show a control of crystal growth via protein-mediation. The results could have significant implications in tailoring formation and assembly of ordered structures in nano- and molecular technologies.[4,5]
- M. Sarikaya, “Materials fabrication through biomimetics,” PNAS, 96, 14183 (1999).
- S. Brown, “Metal recognition by repeated polypeptides,” Nature Biotech., 15, 269 (1997).
- S. Brown, M. Sarikaya, and E. Johnson, “A genetic analysis of crystal growth,” J. Mol. Biol., 299, 725 (2000).
- R. F. Service, “Building the small world of the future,” Science, 286, 2442 (1999).
- Updated research results will be presented in the paper prepared for this conference.
University of Washington, Materials Science and Engineering
Roberts Hall, Box: 352120
Seattle, WA 98195, USA