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OCR for page 12
ONR Research Opportunities in Chemistry 5 Biomolecular Chemistry Biomolecular chemistry, which concerns the study of chemical processes at the interface of chemistry and biology, is a relatively new and largely unexplored area. Materials of controlled structure are needed for biomaterial, electronic, photonic, and medical applications. Nature makes materials of precisely controlled architectures that perform various functions, including, for example, catalysis, structural support, and information processing and storage. The study of such materials has the potential to provide fundamental knowledge that can be used to advantage in the design and preparation of new systems. A better understanding of chemical reactions underlying biological systems is in turn expected to lead to a better ability to design novel materials with properties that equal or exceed those of the naturally occurring materials upon which they are based. The ability to control surface functional groups, chain length, topology, and structure is critical to the design of novel materials that can be beneficial for naval applications. Recent advances in molecular genetics, combinatorial chemistry, and the design of semisynthetic enzymes and catalytic antibodies provide unique opportunities for new applications. An attractive possibility is to use DNA templates to prepare polymers having controlled molecular dimensions and judiciously placed functional groups and chain folding patterns. Such materials are difficult if not impossible to prepare by current synthetic polymerization methods. This potential capability to control the folding of macromolecular chains will lead to materials with improved strength and elasticity, as well as other desired properties. Application of the technology to the incorporation of “unnatural” amino acids and carbohydrates will significantly expand the scope of available materials. For example, it will be possible to precisely vary by design the hydrophilic and hydrophobic surface characteristics of materials. Another area of research where biological chemistry is poised to have a significant impact is in the development of high-strength materials. For example, some forms of silk, such as spider dragline, have been synthesized in the laboratory using DNA templates and have been found to be stronger than steel, as strong as Kevlar®, but much more elastic. Thus, it may be possible to develop materials based on naturally occurring biopolymers to use as lightweight reinforcement for superior composites. However, the molecular-level understanding of the parameters that control the properties of such materials is lacking. Hence, a vigorous research program in the area is highly desirable. An added benefit lies in the design of new synthetic routes to producing protective clothing, composites, and materials that have a better potential for being compatible with substances in living systems. An intriguing prospect in this area is the possibility of combining naturally occurring segments with synthetic polymer segments to give hybrid materials that will synergistically incorporate the useful properties of both systems. Opportunities exist here for property-directed synthesis of novel materials that can be tailored to naval applications. Research at the interface of biology and chemistry will lead to a better understanding of the factors that control bioadhesion and ultimately biocorrosion, two areas of major concern to the Navy. Adhesion of marine organisms to naval structures leads to fouling, and known
OCR for page 13
ONR Research Opportunities in Chemistry methods of combating the problem are increasingly limited by environmental concerns. Biogenetic synthesis can be used to incorporate appropriate functional groups, which may be designed to migrate to the surface of a protective coating, thereby controlling marine biofilm formation. Mechanistic understanding of bioadhesion is critically needed for control of fouling and biocorrosion and represents the critical input for this material design effort. Continued research into the mechanisms of bioadhesion is an area of opportunity. Another area in which research at the interface of chemistry and biology is expected to have an impact is in the design of physical methods for fast genetic analysis. Combinatorial synthesis is making available arrays of materials for numerous applications, including coatings and films. However, the design of appropriate processes for synthesizing molecular arrays and physical methods for measurement and analysis of surface properties are lagging. Hence, a concerted effort in both synthetic methods research and research designed to exploit the atomiclevel characterization offered by the new forms of microscopy—scanning tunneling microscopy, atomic force microscopy, and near-field optical microscopy—is timely. These techniques will lead to new, robust, and fast analytical methods. New biomaterials are needed in applications such as wound healing, bone replacement, and controlled delivery of biologically active species. Biomolecular chemistry is poised to have a significant impact on the availability of biocompatible materials. It is important to know that current biomaterials have not been designed for such uses but have been chosen empirically from materials developed for nonbiological uses. In some cases this empirical approach has led to serious immunogenic complications. Understanding the fundamentals of biological performance at the molecular level will facilitate incorporation of biocompatible segments into synthetic systems for use in medical applications.
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