Date of Award

12-1-2012

Degree Type

Dissertation

University or Center

Clark Atlanta University(CAU)

School

School of Arts and Sciences

Degree Name

Ph.D.

Department

Chemistry

First Advisor

Dr. Ishrat M. Khan

Second Advisor

Dr. Myron M. V. Williams

Third Advisor

Dr. Michael Williams

Abstract

Understanding surface-cell interactions is essential to fabricating a successful biomaterial. In vivo, cells interact with asymmetric features on the micro- and nanoscale. Some of these features, described as valleys, ridges, and spheres, are random, but methodically placed. There are many techniques used to duplicate the topographical features that cells encounter, many of which rely on precision and are labor intensive. Alternatively, the synthetic poly(2-methoxystyrene) (P2MS) homopolymer selfassembled into desirable features, was easily processed and produced the random surface preferred by cells. The features achieved with P2MS were the result of secondary and tertiary conformations confirmed by circular dichroism. The features were also a consequence of the optical activity revealed by polarimetry. Advanced microscopy verified that the features were indeed biomimetic and measured between 150—600 nm in depth and height. Polymers were synthesized using free radical and anionic techniques; some involved the use of a chiral initiator. Spin-casting and solvent annealing were employed to create polymer films for substrate-cell studies. Reaction conditions and molecular weight were varied to achieve different topographical features and thermal profiles. In showing that the films were able to be sterilized, the films were further subjected to cytotoxicity studies involving both Escherichia coli and Bacillus cereus. The results of turbidity measurements and colony counting revealed increased cell viability. The gram positive bacteria, B. cereus, showed increased adhesion through hydrophobic interactions, the same type of interactions proteins rely on for deposition prior to cell adhesion. The cell adhesion study used the human epithelial carcinoma (HeLa) cell line, and showed increased adhesion on chiral initiated P2MS. As a result, this work verified that topographical features can influence cell behavior without the presence of biochemical cues and that P2MS may provide a viable option for tissue engineering applications.

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