Identifier

etd-05252010-142640

Degree

Doctor of Philosophy (PhD)

Department

Chemical Engineering

Document Type

Dissertation

Abstract

A novel gel material was designed and optimized for use as a bone tissue regeneration scaffold. Whey protein isolate (WPI), the primary component of the material, underwent considerable testing for conformity to a set of known material characteristics required for application in bone regeneration. WPI gels of different compositions were fabricated by thermally inducing gelation of high-concentration protein suspensions, and characterized for compressive strength and modulus, hydration swelling and drying properties, mechanical behavior change due to polysaccharide additives, and intrinsic pore network structure. The gels were also tested for their compatibility with MC3T3-E1 cells, and interactions such as cell adhesion, cytotoxicity, proliferation kinetics, and bone formation, were characterized for gels of different compositions. Some properties of interest were composition- and processing-dependent, while others varied little with such variables. Results revealed that the most favorable mechanical properties could be obtained by using a material of 40% w/v WPI, 10 mM CaCl2, and 0.2 g amylopectin per g WPI. The mechanical properties of this composite approached the ultimate strength necessary for a load-bearing scaffold, and were within one order of magnitude of the lower limit of the necessary compressive modulus. The proper modulus could likely be achieved by converting the conventional composite to a nanocomposite. The observed cell-scaffold interactions were highly suitable. All tested naïve gels and composites supported the adhesion and proliferation of the model cell line for extended culture periods. Amylopectin incorporation decreased initial preosteoblast adhesion but improved the proliferation rate constant – the more important system parameter. Both the naïve gel and the composites enabled cells to differentiate and create bone in vitro, and sustained viability for the length of the 4-week study. The current fabrication technique left insufficient porosity and interconnectivity for a bone scaffold, though the necessary pore size distribution was achieved. The effect of WPI concentration and precursor suspension viscosity on these properties was thoroughly characterized. In order to correct the disparity in properties, a method for electrospinning WPI was developed, and shows great promise. While further studies are required, the developed composite has significant potential for implementation in the industry.

Date

2010

Document Availability at the Time of Submission

Secure the entire work for patent and/or proprietary purposes for a period of one year. Student has submitted appropriate documentation which states: During this period the copyright owner also agrees not to exercise her/his ownership rights, including public use in works, without prior authorization from LSU. At the end of the one year period, either we or LSU may request an automatic extension for one additional year. At the end of the one year secure period (or its extension, if such is requested), the work will be released for access worldwide.

Committee Chair

Henry, James E.

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