The Macromolecular, Supramolecular and Nanochemistry (MSN) Program at the National Science Foundation supports the research of Professor Vincent P. Conticello of Emory University. This project focuses on the synthesis and structural characterization of collagen-mimetic fibrils derived from self-assembly of designed peptides. Collagen is the main structural component of the extracellular matrix and is responsible for guiding the development and maintaining the structural integrity of tissues in human systems. Currently, collagen derivatives for medical applications are drawn primarily from animal sources, however the development of synthetic collagen derivatives is a highly desirable objective, particularly if the chemical, biological, and mechanical properties of the materials could be tailored to maximize their efficacy with respect to a given function. This proposal evaluates the potential for the creation of synthetic collagen fibers on the basis of structural considerations uncovered from analysis of model collagen peptides. The results of these studies will be of interest not only in generating synthetic collagenous materials that mimic native structural proteins, but also for the design of novel structures with functional properties that exceed those of the materials currently available from animal sources.
This project is focused at the interface of chemistry, biology, materials science, and nanotechnology and provides training for graduate and undergraduate students in inter-disciplinary research in a technologically significant area. Undergraduate students are selected from among participants that are involved in the Summer Undergraduate Research Experience at Emory (SURE) program. SURE is organized and administrated out of the Emory College Center for Science Education (ECCSE), a satellite university center responsible for the promotion of undergraduate access, interest, and participation in the sciences. In addition, NSF funding provides support to high-school chemistry teachers for six weeks during the summer. Each teacher will spend time on research and on translating the research experience into a lesson plan for high school students or colleague teachers.
Recent advances in the structural analysis of biological assemblies have provided significant insight into the mechanisms that underlie the function of the complex molecular machines that sustain life. The information obtained from these studies promises an unprecedented opportunity for the creation of functional nano-scale materials derived from self-assembly of biological structural motifs such as proteins. Historically, structurally defined materials on the nanometer length-scale have been the most challenging to rationally construct and the most difficult to structurally analyze. Proteins have an advantage as design elements for the construction of nano-scale materials in that they fold into well-defined, folded structures on the basis of sequence information. The correlations between sequence, structure, and function can be utilized to create artificial proteins of uniform and controllable architecture that self-assemble into a variety of structurally defined supramolecular materials that exhibit distinctive properties vis-à-vis conventional organic polymers. Under NSF funding, structurally defined one-dimensional (nanofibers and nanotubes) and two-dimensional (nanosheet) nano-scale objects have been created from self-assembly of short protein sequences. These objects display a high degree of structural uniformity that has been encoded within the amino acid sequence of the protein. Moreover, the structural uniformity of these materials permits the introduction of function into the materials. Nanofibers have been engineered that reversibly assemble in response to the presence of a metal ion. Nanotubes have been designed that can encapsulate small molecule guests within the central channel. Nanosheets can be constructed with defined chemistry at the sheet surface, which enables them to serve as platforms for controlled presentation of substrates. These protein-based materials have the potential to serve in diverse functions including dynamic switching, locomotion, controlled release, directional transport, templation, and selective catalysis. These functions are representative of the roles of proteins in living systems, but have been difficult to reproduce in synthetic systems on the nano-scale. The success of this research depended on the participation of individuals including graduate students, under-graduate students, high-school students, high-school teachers, and research scientists. The research also benefitted from the involvement of collaborators at domestic and international academic institutions as well as national laboratories.
