STUDY ON BIOCOMPATIBILITY OF Zr ALLOY AND Mg COMPOSITE USED FOR ORTHOPEDIC APPLICATIONS

Abstract

The area of tissue engineering has advanced dramatically in the last 10 years, tissue engineering offers the potential for regenerating possibly all tissue and organ of the human body. Tissue engineering and the related discipline of regenerative medicine remain a flourishing area of research with potential new treatments for many more disease states. The advances involve researchers in a multitude of disciplines, including cell biology, biomaterials science, imaging, and characterization of surfaces and cell material interactions. Tissue engineering aims to restore, maintain, or improve tissue functions that are defective or have been lost by different pathological conditions, either by developing biological substitutes or by reconstructing tissues. In present study biocompatibility of Zircaloy-2 and Mg composite has been evaluated, for their potential application as orthopedic implant. The multimodal structure, i.e. the combination of coarse, ultrafine gained (UFG) and nanograined structure of Zircaloy-2 is obtained by cryorolling the bulk alloy followed by annealing at 400° C, and 450° C for 30 minutes. An estimation of surface wettability of the alloy was obtained through contact angle measurement. The bioactivity of the alloy samples was investigated by incubating bone marrow derived stem cells. The cellular attachment, adhesion and proliferation at different intervals of incubation were characterized by scanning fluorescent microscopy and MTT assay. Cell culture results indicated that liquid nitrogen rolled alloy samples exhibited excellent in-vitro biocompatibility together with satisfactory bioactivity. Excellent genomic expressions were observed for Zircaloy-2 processed by cryorolling. Corrosion behavior was tested using cyclic polarization with 3.5% NaCl. or Whereas the Mg-HA(Mg-Hydroxyapatite) composite was fabricated through mixing of powders via ultrasonication followed by sintering at 5500 for 3 hours. Structural analysis was performed by using XRD; powder morphologies were determined through SEM. In order to evaluate the hydrophilicity contact angle with water drop on the implant surface was measured. For the composition and distribution of the elements EDAX mapping were performed. Biocompatibility was tested by incubating bone morrow derived stem cell on the composite surface for the time interval of I and 3 days hours. Corrosion behavior was tested using Tafel analysis with 3.5% NaCl. For the convinience of undrstanding I have divided the thesis into two parts, first part contains the studuy on biocompatbility of Zircconium alloy, whereas the second part of the thesis represents the Biocompatibility study of Mg-HA functionally graded composite.