Bioengineering Single Crystal Growth

Northwestern University, Evanston IL

Investigators

Abstract

ID: MPS/DMR/BMAT(7623) 0805313 PI: Joester, Derk ORG: Northwestern University Title: Bioengineering Single Crystal Growth INTELLECTUAL MERIT: Despite the highly attractive properties of biological mineralized tissues and great recent progress in bio-inspired materials synthesis, many of the hallmarks of biological crystal growth have yet to be reproduced in vitro: polymorph control, curving and/or branching single crystals, and nm scale control of organic-inorganic composites. Much could be gained by developing a biotechnological alternative to bulk materials synthesis. In this proposal the PI will explore micro-patterned cell culture of sea urchin embryonic primary mesenchyme cells (PMCs) as a means to guide the cellular machinery responsible for single crystal synthesis. In this way the project will take advantage of a fully capable synthetic engine and attempt to reprogram it. This will then provide the basis for investigating and ultimately reverse engineering it in vitro. The following specific tasks will be pursued to explore and develop the range and limits of engineering single crystal shape, connectivity, and larger composite structures by guided biological deposition: (1) Develop micro-patterning to control the placement of PMCs on a surface. In this way, guide the biological deposition of single calcite (CaCO3) crystals. In particular, establish pattern topography, adhesiveness, chemotaxis induced by vascular endothelial growth factor (VEGF), and limiting cell numbers and densities. (2) Explore junction patterns to reproduce the biological tri-radiate branching or fusion of two individual single crystalline elements. Combine simple shapes and junctions for increasingly complex crystal shape and connectivity in 2D and 3D. (3) Further characterize the biological crystal growth machinery with respect to routes of mineral/protein trafficking, amorphous precursor phases, and amorphous-to crystalline transitions by a complementary suite of techniques including live cell imaging, IR and Raman microscopy, and electron microscopic imaging. BROADER IMPACTS: The proposed research promises a major advance in harnessing biosynthetic mineralization pathways to create useful ceramic structures. The project also includes a thorough plan for integration of research and education. The PI will develop a full quarter undergraduate course in biomineralization designed to train students in communications skills, expose them to professional peer review, and assess their analytical skills. Students will disseminate the knowledge gained through an online, public access WIKI that will be written, reviewed, and edited by students. A design competition will be held to develop new cell culture devices for guided crystal growth and thus draw students into questions actively researched in the PI?s laboratory and engage their engineering skills in a trans-disciplinary project. Undergraduate research opportunities in the PI?s lab will provide highly interdisciplinary cross training in bio-related areas such as sea urchin husbandry, cell culture, and live cell imaging, and these activities will complement training in clean room photolithography and materials characterization by advanced imaging techniques. Outreach to high school students will be targeted to ethnically diverse neighborhoods of Chicago, Rogers Park, and Evanston. As all current graduate students in the lab are female, an especially focused projection of positive female role models will be achieved. In conjunction with high school science teachers, engineering and biomaterials class modules, visits on the Northwestern Campus, and a summer internship program will be organized.