1. These structures may be hierarchical;3 i.e., they may be organized on multiple length scales with multiple functions at each scale.
  2. The systems that they form consist of several components.

The following specific examples of current research may help to give the reader an idea of the character of this exciting field:

  • Polymer biosynthesis.4 Biosynthetic routes are being explored for the preparation of biobased polymers: natural fibers, modified versions of natural proteins, and synthetic proteins that have no close natural analogues.
  • Self-assembled monolayers and multilayers.5 The phase behavior of self-assembling surfactant monolayers on both fluid and solid substrates is being mapped out. These monolayers are effective in applications such as lithographic masking and high-resolution reaction templating. They also have potential as chemical sensors, as nonlinear optical elements, in neuronal networks, and for environmentally safe metal plating. Stable multilayer films of polymeric systems have been fabricated and their activity demonstrated. This approach is expected to lead to the development of functional organic films.
  • Decorated membranes.6 For many years, lipid bilayer membranes have been investigated as models for cell walls. Current research is focusing on active membranes that mimic natural membrane function by including bound proteins, adsorbed colloidal particles, and so on.
  • Mesoscopic organized structures.7 Biomolecular systems that spontaneously organize into crystalline structures with lattice constants in the mesoscopic range are being studied as molecular sieves (S-layers), 8 electrically active arrays (tubules),9 and long-term controlled-release systems (vesicles).10
  • Biomineralization.11 Biomolecular templates are being studied as nucleation devices for the synthesis of inorganic compounds with unusual structures and high degrees of perfection. Examples include the epitaxial growth of carbonates induced by molluscan shell protein and the intracellular synthesis of CdSe semiconductors.

These specific models of contemporary biomolecular materials research have encouraged the panel to examine more speculative possible long-term goals. Some examples are discussed in Section 3 of this report, “Opportunities.”

3  

The materials addressed in this report are organized on the molecular to membrane length scales. A report entitled Hierarchical Structures in Biology As a Guide for New Materials Technology (National Academy Press, Washington, D.C., 1994), prepared under the aegis of the National Materials Advisory Board of the National Research Council, concentrated on more complex cellular or extracellular materials.

4  

J.G. Tirrell, M.J. Fournier, T.L. Mason, and D.A. Tirrell, Chemical and Engineering News 72:40 (1994).

5  

L.H. Dubois and R.G. Nuzzo, “Synthesis, Structure, and Properties of Model Organic Surfaces,” Annu. Rev. Phys. Chem. 60:437 (1992); A. Ulman, Ultrathin Organic Films (Academic Press, Boston, 1991).

6  

N. Unwin and R. Henderson, Scientific American 250(February):78 (1984).

7  

National Research Council, Hierarchical Structures in Biology As a Guide for New Materials Technology (National Academy Press, Washington, D.C., 1994).

8  

U.B. Sleytr and M. Sara, Appl. Microbiol. Biotechnol. 25:83 (1986); W. Baumeister and G. Lembcke, J. Bioenerg. Biomembr. 24:567 (1992).

9  

J.M. Schnur, Science 262:1669 (1993).

10  

D.D. Lasic, Liposomes: From Physics to Applications (Elsevier, Amsterdam, 1993).

11  

Stephen Mann, John Webb, and Robert J.P. Williams, eds., Biomineralization: Chemical and Biochemical Perspectives (VCH, New York, 1989).



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