Defense Date

2-15-2011

Graduation Date

Spring 2011

Availability

Immediate Access

Submission Type

dissertation

Degree Name

PhD

Department

Chemistry and Biochemistry

Committee Chair

Ellen Gawalt

Committee Member

Mihaela-Rita Mihailescu

Committee Member

Jeffrey Evanseck

Committee Member

Kenneth McGowan

Keywords

Antibiotic, Bone scaffold, KRSR, Surface modification

Abstract

Calcium aluminates were tested as biomaterials and show promise as bone scaffolds. Initial concerns of biocompatibility led the field to focus on calcium phosphates. Here, the work focused on improving the biocompatibility and creating an optimized calcium aluminate biomaterial. To accomplish this, the physical and interfacial properties of the material were varied. The physical properties of the calcium aluminate were varied through the room temperature casting procedure and five different mixtures were created and evaluated for mechanical strength and biotolerability. The results showed that the optimal mixture had an average pore size of approximately 100 µm and that autoclaving the material increased the strength and therefore was the best sterilization method for all studies. Following optimization of the physical properties, the cell adhesion peptide KRSR was immobilized onto the surface to increase specific osteoblast adhesion and RGD was immobilized as a non-cell specific peptide control. It was determined that KRSR preferentially increased osteoblast over fibroblast adhesion and increased osteoblast adhesion compared to unmodified and RGD modified calcium aluminate which is important for a bone scaffold material. Biofilm formation and implant associated infections are still a significant problem despite advancements in sterile techniques in operating rooms. To mitigate bacterial attachment, vancomycin and ampicillin were successfully immobilized on the surface through both covalent attachment and adsorption. Vancomycin remained active after autoclaving and was extremely effective at inhibiting bacterial growth when compared to unmodified calcium aluminate and the control antibiotic dosage. Finally, both KRSR and vancomycin were simultaneously immobilized utilizing three different attachment schemes. A double immobilization scheme that allowed for antibiotic activity and increased osteoblast attachment was found producing an optimized calcium aluminate material for use as a bone scaffold.

Format

PDF

Language

English

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