Natural polymers Nanotechnology

In this chapter we describe the basic principles involved in the controlled production and modification of two-dimensional protein crystals. These are synthesized in nature as the outermost cell surface layer (S-layer) of prokaryotic organisms and have been successfully applied as basic building blocks in a biomolecular construction kit. Most importantly, the constituent subunits of the S-layer lattices have the capability to recrystallize into iso-porous closed monolayers in suspension, at liquid-surface interfaces, on lipid films, on liposomes, and on solid supports (e.g., silicon wafers, metals, and polymers). The self-assembled monomolecular lattices have been utilized for the immobilization of functional biomolecules in an ordered fashion and for their controlled confinement in defined areas of nanometer dimension. Thus, S-layers fulfill key requirements for the development of new supramolecular materials and enable the design of a broad spectrum of nanoscale devices, as required in molecular nanotechnology, nanobiotechnology, and biomimetics [1-3]. 

The unique power of synthesis is the ability to create new molecules and materials with valuable properties. This capacity can be used to interact with the natural world, as in the treatment of disease or the production of food, but it can also produce compounds and materials beyond the capacity of living systems. Our present world uses vast amounts of synthetic polymers, mainly derived from petroleum by synthesis. The development of nanotechnology, which envisions the application of properties at the molecular level to catalysis, energy transfer, and information management has focused attention on multimolecular arrays and systems capable of self-assembly. We can expect that in the future synthesis will bring into existence new substances with unique properties that will have impacts as profound as those resulting from syntheses of therapeutics and polymeric materials. 

T. Ramanathan, A.A. Abdala, S. Stankovich, D.A. Dikin, M. Herrera-Alonso, R.D. Piner, et al., Functionalized graphene sheets for polymer nanocomposites, Nature Nanotechnology, 3 (2008) 327-331. 

Paul van der Schoot, Nucleation and Co-Operativity in Supramolecular Polymers Michael J. McPherson, Kier James, Stuart Kyle, Stephen Parsons, and Jessica Riley, Recombinant Production of Self-Assembling Peptides Boxun Leng, Lei Huang, and Zhengzhong Shao, Inspiration from Natural Silks and Their Proteins Sally L. Gras, Surface- and Solution-Based Assembly of Amyloid Fibrils for Biomedical and Nanotechnology Applications... 

It appears that fluorescence techniques are poised to receive more serious consideration for accelerated development efforts. Key obstacles remaining include stability of receptors and fluorophores, challenges that will possibly be met partially by results of the intense efforts of molecular biology, polymer science, and nanotechnology. Advances in nanomaterials such as quantum dots will likely enable improvements in optical stability and choice of excitation/emission wavelengths for various transduction methods. Stabilization of natural and artificial enzymes and rendering immunogenic protein receptors stealthy may also aid the pursuit. 

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