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|Title||Microstructure, Corrosion Behavior, Mechanical Property and Biocompatibility of Compression-molded Zinc-nanodiamond Composites as a Bio-implant Material|
Biodegradable metals have been widely studied in recent years as potential biomedical implant materials. These bio-implants are expected to provide mechanical support during healing and then degrade thereafter causing minimum toxicity to surrounding cells and tissues. But current biodegradable magnesium alloys demonstrate major drawbacks, including fast degradation rates and relatively complicated manufacturing conditions. In this dissertation, a novel material, Zinc-nanodiamond (Zn-ND) composite, was proposed and studied because of its desirable corrosion and biocompatible properties. The microstructure, corrosion behavior, mechanical properties and biocompatibility of Zn composites were investigated and powder metallurgy manufacturing processes were used to manufacture the composites.Grain size increased with higher sintering temperature and longer sintering time. Corrosion resistance was improved 61.0%, 65.9% and 70.7% for 1%, 2.5% and 5% ND compared with pure Zn. Compression and hardness tests were performed to determine the mechanical properties. In the compression tests, Zn-1ND showed the highest Young's modulus, 10.95% and 27.32 % more than pure Zn and Zn-5ND. Pure Zn had the highest compressive strength, 11.8% and 29.5% higher than Zn-1ND and Zn-2.5ND. Zn-1ND and Zn-2.5ND are 55.2 % and 68.9 % lower in hardness compared with pure Zn (HV = 27).In the biocompatibility tests, mouse osteoblasts (7F2) were treated with different concentrations of zinc chloride (ZnCl2) media, powders mixed media, and disc extracts. A normal proliferation pattern was observed for cells treated with 0.1 mM ZnCl2 media, while cells treated with powder mixed media presented a decreasing trend in cell proliferation. Compared with control group, there were 20.41%, 59.3%, 36.33% and 46.35% fewer cells for pure Zn, Zn-1ND, Zn-2.5ND and Zn-5ND, respectively. The cell viability was measured by live/dead and Alamar blue assays. Cells remained viable when treated with less than 0.5 mg/mL powder mixed media, or 10% of the sample extracts. This study demonstrates compression-molded zinc with low concentrations of nanodiamond offers a promising combination of strength, low corrosion rate, and biocompatibility, that can be potentially used as a biodegradable implant material.
Ph.D., Mechanical Engineering and Mechanics – Drexel University, 2014
|Subjects/Keywords||Mechanical engineering; Biocompatibility; Materials – Biodegradation|
|Contributors||Zhou, Jack; College of Engineering|
|Country of Publication||us|