The Woodruff School

SUMMARY

As an essential structural component, scaffold plays a significant role in the development of a vascular substitute by hosting seeded cells, promoting their cellular activities and controlling their thrombotic/inflammatory responses to form a new tissue. For such a scaffold to be successful, the selected materials should possess stable mechanical properties and appropriate chemical functionalities in order to sustain all the required parameters. Cellulose nanowhiskers (CNWs), an abundant, biocompatible material, could potentially be a feasible scaffold candidate in tissue engineering of a new vessel. Due to their exceptional properties, CNWs could integrate a nanofibrous porous network with superior structural diversity and functional versatility. The moldable nature, mechanical strength in the wet state, stable functionality and durability could render the cellulose-based biomaterial a revolutionary candidate in vascular tissue engineering. Inspired by the bio-applications of cellulose and its derivatives, we have designed a biomaterial taking advantage of the aligned nano-sized whiskers. Comparable to Carbon Nanotubes and Kevlar, CNWs impart a significant strength and a directional rigidity at only 0.2 wt% yet double that at 3.0 wt% and intensify to an almost twofold increase within an externally applied magnetic field of 0.3T. The aligned profile feature not only improved the directionality and percolation of nanofibers within the medium, but also drastically lowered the optimum amount of CNWs required to obtain the best composite performance. In order to verify the accuracy of our experimental data and to predict the unusual reinforcing effect of CNWs in cellulose-based nanocomposites at such low filler content, theoretical models such as the mean field approach and the percolation technique were also investigated in this study. Based on these comparisons, the tendency of cellulose nanowhiskers to interconnect with one another through strong hydrogen-bonding confirmed the formation of a three-dimensional rigid percolating network, fact which imparted an excellent mechanical stability to the entire structure at such low fiber concentration. We believe that our nanohybrid material not only could expand the biomedical applications of renewable cellulose-based materials but also could provide a potential scaffold in vascular tissue engineering.

SUBJECT:	Ph.D. Proposal Presentation

BY:	Parisa Pooyan

TIME:	Friday, November 18, 2011, 1:00 p.m.

PLACE:	MRDC Building, 4211

TITLE:	Cellulose-based Scaffolds in Cardiovascular Tissue Engineering

COMMITTEE:	Dr. Cyrus Aidun, Co-Chair (ME) Dr. Hamid Garmestani, Co-Chair (MSE) Dr. Rina Tannenbaum (MSE) Dr. David Ku (ME, BME) Dr. David McDowell (ME, MSE) Dr. Maziar Zafari (Emory, School of Medicine)

SUMMARY As an essential structural component, scaffold plays a significant role in the development of a vascular substitute by hosting seeded cells, promoting their cellular activities and controlling their thrombotic/inflammatory responses to form a new tissue. For such a scaffold to be successful, the selected materials should possess stable mechanical properties and appropriate chemical functionalities in order to sustain all the required parameters. Cellulose nanowhiskers (CNWs), an abundant, biocompatible material, could potentially be a feasible scaffold candidate in tissue engineering of a new vessel. Due to their exceptional properties, CNWs could integrate a nanofibrous porous network with superior structural diversity and functional versatility. The moldable nature, mechanical strength in the wet state, stable functionality and durability could render the cellulose-based biomaterial a revolutionary candidate in vascular tissue engineering. Inspired by the bio-applications of cellulose and its derivatives, we have designed a biomaterial taking advantage of the aligned nano-sized whiskers. Comparable to Carbon Nanotubes and Kevlar, CNWs impart a significant strength and a directional rigidity at only 0.2 wt% yet double that at 3.0 wt% and intensify to an almost twofold increase within an externally applied magnetic field of 0.3T. The aligned profile feature not only improved the directionality and percolation of nanofibers within the medium, but also drastically lowered the optimum amount of CNWs required to obtain the best composite performance. In order to verify the accuracy of our experimental data and to predict the unusual reinforcing effect of CNWs in cellulose-based nanocomposites at such low filler content, theoretical models such as the mean field approach and the percolation technique were also investigated in this study. Based on these comparisons, the tendency of cellulose nanowhiskers to interconnect with one another through strong hydrogen-bonding confirmed the formation of a three-dimensional rigid percolating network, fact which imparted an excellent mechanical stability to the entire structure at such low fiber concentration. We believe that our nanohybrid material not only could expand the biomedical applications of renewable cellulose-based materials but also could provide a potential scaffold in vascular tissue engineering.