The research objective of this award is to create a new class of nanostructured biological scaffolds that exhibit a negative Poisson's ratio (auxetic surfaces), and study their ability to modulate the cell shape, adhesion, proliferation and cytoskeletal re-orientation. The ability of a biomaterial scaffold to support and transmit cell and tissue forces can be quantitatively described by its elastic modulus and Poisson's ratio. Recent studies have shown that elastic modulus can modulate a variety of cell types. However, the effect of Poisson's ratio on cell behavior has been largely ignored. While most natural materials have a positive Poisson's ratio and contract (expand) transversally when stretched (compressed) in a certain direction, auxetic materials exhibit an unusual property of having a negative Poisson's ratio, i.e., they expand transversally when stretched and vice versa. To achieve the research objectives, the team will design, fabricate, and characterize nanoscale auxetic surface topographies that exhibit a negative Poisson's ratio using polyethylene glycol biomaterial. The team will investigate the auxetic effect in the nanoscaffolds on the adhesion, cytoskeletal organization, and shape of adipose derived human stem cells. If successful, this work will be the first in the field for developing nanoscale scaffolds with a negative Poisson's ratio and studying the cellular responses to such novel scaffolds. The PI has an outstanding track record of research in nanofabrication, biomaterials, and cell interactions with microenvironments. UC San Diego and the PI's laboratories offer excellent facilities and resources for this project.
An auxetic scaffold could match both the elastic stiffness and the Poisson's ratio of the host tissue and would likely better integrate with native tissues and better promote clinical tissue regeneration. Methodology developed in this work can be extended to other biomaterials and cell-types to investigate effects of altering the Poisson's ratio on a variety of cellular aspects for arterial endothelium, myocardial patch, skin and fat tissue engineering, medical sutures, and in wound management. Thus this work directly aids scientific progress, benefits healthcare and society at large. The proposed research is highly interdisciplinary, involving tissue engineering, nanomanufacturing, and biomaterials. Results from this project will be excellent teaching materials for undergraduate and graduate students. The strong educational efforts for K-12 and minority students will attract more young students and under-represented students into engineering, and particularly into the interdisciplinary field between engineering and biology.
