SUBJECT: Ph.D. Dissertation Defense
BY: Parisa Pooyan
TIME: Monday, March 17, 2014, 12:00 p.m.
PLACE: MRDC Building, 3515
TITLE: Bio-inspired Polymer Nanocomposites for Tissue Engineering Applications
COMMITTEE: Dr. Hamid Garmestani, Co-Chair (MSE)
Dr. Karl Jacob, Co-Chair (ME)
Dr. Cyrus Aidun (ME)
Dr. Luke Brewster (Emory, Vascular Surgery Division)
Dr. David McDowell (ME)
Dr. Rina Tannenbaum (MSE)
Dr. Maziar Zafari (Emory, Cardiology Division)


Increasing emphasis has been placed on the use of renewable resources, to rely less heavily on petroleum and to better utilize global energy needs. Biological structures available in nature have been a constant inspiration to the design and fabrication of the new line of functional biomaterials where their unique phenomena enable novel applications. In tissue engineering for example, a natural biomimetic material with close resemblance to the profile features existed in a native extracellular matrix could provide a temporary functional platform to regulate and control cellular interactions with the material at a molecular level and subsequently in directing a tissue regeneration. However, the lack of rigidity of nature's materials typically limits their mass production. One promising approach to address this shortcoming is to introduce a biomimetic composite material reinforced by high purity nanofibers found in nature. As a attractive reinforcing filler phase, cellulose nanowhiskers (CNWs) could integrate a viable nanofibrous porous candidate, resulting in superior structural diversity and functional versatility due to their exceptional properties such as high aspect ratio, large interface area, and significant mechanical performance. Inspired by the fascinating properties of cellulose and its derivatives, we have designed two bio-inspired nanocomposite materials reinforced with CNWs in this work. The successful grafting of CNWs within the host matrix and their tendency to interconnect with one another through strong hydrogen bonding gave rise to the formation of a three-dimensional rigid percolating network, fact which imparted considerable mechanical strength and thermal stability to the entire structure with only a small amount of filler content, i.e. 3 wt.%. The biocompatibility of the nanocomposite was also probed by an in-vitro incubating of human bone marrow derived mesenchymal stem cells (MSCs), resulting in the invasion and proliferation of MSCs around the material at day 8 of culture. The green functional biomaterial with its unique features in this work could open new perspective design in the self-assembly of nanobiomaterial for scaffolding in tissue engineering.