Biomedical implants are commonly made from commercially pure titanium and other metal alloys, which are chosen for their strength and density. To improve the stability and promote bone cell growth into the implant, efforts to bond coatings to metal have been extensively studied. Many coatings used are considered bioactive, which promote the adhesion and growth of the bone cells surrounding the implant [A.1]. Of these, the most commonly investigated coating is a ceramic called hydroxyapatite, which is brittle, leading to flaking and inadequate bone cell growth [A.2]. Alternate bioactive coatings are being examined, including chitosan, the deacetylated form of chitin. Chitin is the second most abundant polymer in nature [A.3] and is found in the exoskeletons of insects and shellfish [A.4]. Chitosan has been proven to have excellent biocompatibility [A.5], be non-toxic [A.3], and promote the adhesion and growth of bone cells [A.6 ? A.7]. In this research, four treatment combinations were developed and tested in an attempt to improve film bonding. These treatment combinations were created using one of two silane molecules, aminopropyltriethoxysilane and triethoxsilylbutyraldehyde, and one of two metal treatments, passivation and piranha treatment. XPS was used to characterize the reaction steps for each of the treatment combinations. A significant decrease in TiO, along with significant increases in SiOx groups, C ? N ? H, and C = O, indicated that the reactions were proceeding as expected. XPS also indicated that, chemically, the chitosan films were not significantly different and were unchanged by the treatment combinations. Following chemical analysis, mechanical testing was performed on the four treatment combinations. No changes to the bulk properties were seen as demonstrated by nano-indentation, further indicating that the four treatment combinations did not change the chemical properties of chitosan. The bulk adhesion of the films was greatly improved for all four treatment combinations, as demonstrated by tensile testing. The highest value from this research, 19.50 ± 1.63 MPa, was significantly higher than the previously published results of 1.6 ? 1.8 MPa [A.10]. Overall, the treatments developed in this study significantly improved the adhesion of the chitosan film on the titanium substrate, without modifying the chemical or structural properties of chitosan. [A.1] Ratner, B. D. and A. S. Hoffman. Biomaterials Science: An Introduction to Materials in Medicine. California: Academic Press, Inc., 1996, Foreword, 1-8. [A.2] S.D. Cook, K.A. Thomas, J.F. Kay. ?Experimental Coating Defect in Hydroxylapatite-Coated Implants.? Clinical Orthopaedics and Related Research, 1992, 265, 280-290. [A.3] A.K. Singla, M. Chawla. ?Chitosan: some pharmaceutical and biological aspects- an update.? Journal of Pharmacy and Pharmacology, 2001, 53, 1047-1067. [A.4] Q. Li, E.T. Dunn, E.W. Grandmaison, M.F.A. Goosen. ?Application and Properties of Chitosan.? Journal of Bioactive and Compatible Polymers, 1992, 7, 370-397. [A.5] M. Prasitsilp, R. Jenwithisuk, K. Kongsuwan, N. Damrongchai, P. Watts. ?Cellular responses to chitosan in vitro: The importance of deacetylation.? Journal of Materials Science: Materials in Medicine, 2000, 11, 773-778. [A.6] R.A.A. Muzzarelli, M. Mattioli-Belmonte, A. Pugnaloni, G. Biagini. ?Biochemistry, histology, and clinical uses of chitins and chitosans in wound healing.? Chitin and Chitinases, ed. P. Jolles, R.A.A. Muzzarelli, Switzerland: Birkhauser Verlag Basel, 1990. [A.7] P. Klokkevold, L. Vandemark, E.B. Kenney, G.W. Bernard. ?Osteogenesis Enhanced by Chitosan (Poly-N-Acetyl Glucosaminoglycan) In Vitro.? Journal of Periodontology, 1996, 67, 1170-1775. [A.8] J.D. Bumgardner, R. Wiser, P.D. Gerard, P. Bergin, B. Chestnutt, M. Marini, V. Ramsey, S.H. Elder, J.A. Gilbert. ?Chitosan: potential use as a bioactive coating for orthopaedic and craniofacial/dental implants.? Journal of Biomaterials Science, Polymer Edition, 2003, 14 (5), 423-438.
| Identifer | oai:union.ndltd.org:MSSTATE/oai:scholarsjunction.msstate.edu:td-5285 |
| Date | 09 December 2006 |
| Creators | Martin, Holly Joy |
| Publisher | Scholars Junction |
| Source Sets | Mississippi State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Theses and Dissertations |
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