Theses and Dissertations

Hsin-Yi Lin

Issuing Body

Mississippi State University

Advisor

Bumgardner, Joel D.

Committee Member

Schulz, Kirk H.

Committee Member

Ainsworth, A. Jerald

Committee Member

To, S.D. Filip

Committee Member

Cooper, Robert

Other Advisors or Committee Members

Wipf, David; Elder, Steven H.

Date of Degree

12-13-2002

Document Type

Dissertation - Open Access

Major

Biomedical Engineering

Degree Name

Doctor of Philosophy

College

College of Engineering

Department

Department of Agricultural and Biological Engineering

Abstract

Orthopedic metal implant materials may mediate a variety of adverse tissue reactions by releasing ions through corrosion. Adverse tissue reactions include inflammation, fibrosis and hypersensitivity. All of these reactions eventually lead to implant failure. The goal of this study was to provide a better understanding of the cellular-material interaction at the metal surface. The hypotheses were that 1. the attachment of cells and their released reactive inflammatory compounds (e.g. hydrogen peroxide H2O2, superoxide O2. and nitric oxide NO.) on the surfaces alter the alloys? corrosion and surface properties and 2. the changes in corrosion and chemical properties of the surfaces affect cell behavior. To evaluate the hypotheses, a custom-made electrochemical corrosion cell was used to evaluate how cell culture medium, macrophage cells and macrophage cells activated to simulate inflammation affected the corrosion and surface properties of Co-Cr-Mo and Ti-6Al-4V alloys and how released alloy corrosion products affected cell behaviors. The macrophage cell line used was known to produce reactive species H2O2, O2. and NO. when activated by antigen and interferon. The alloy corrosion properties were enhanced by observing the open circuit potential (OCP), charge transfer, metal ion release, and changes in surface oxides. Proliferation, viability and metabolism were used to evaluate effects of corrosion on the cells. The OCP of Co-Cr-Mo remained unchanged whereas that of Ti-6Al-4V increased over three days for all three test conditions. Both alloys cultured with medium had the lowest OCP among all conditions. With activated macrophage cells, both alloys had the lowest total charge transfer and concentrations of metal ion released. This improved corrosion resistance was mostly due to an enhancement of the surface oxide due to the reactive species released from activated cells, as indicated from the surface analyses. Both alloys were found to have increased percentage (in peak intensity) of O and Ti or Cr peaks, which indicated an increase of Ti and Cr oxides on Ti-6Al-4V and Co-Cr-Mo alloys respectively. The improved corrosion properties resulted in less metal ion release than those without enhanced surface oxides, thus alloys did not further activate cell immune responses in the three day period. The non-activated or activated cells with released metal ions did not exhibit any degradation in their viability, intracellular ATP, NO and IL-1b release as compared to controls. This is consistent with the generally accepted good biocompatibility of these alloys.

URI

https://hdl.handle.net/11668/19641

Comments

implant alloys||corrosion||macrophage cell culture||orthopedic materials||CoCrMo||TiAlV

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