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Coating of biodegradable magnesium alloy bone implants using nanostructured diopside (CaMgSi2O6)

Significance Statement

Stainless steel (e.g., 316L), titanium–based or cobalt–chromium–based alloys are among the most well-known metallic bone implants. However, unfavorable and costly post-surgeries are required for removal of these metallic implants from the body. These complications demand the obligation of researchers to replace the conventional metallic biomaterials by bioresorbable ones. Magnesium alloys, due to their biocompatibility and biodegradability characteristics are among the promising candidates for this purpose. However, the rapid degradation and hydrogen release of magnesium alloy are the key obstacles to employ them for clinical applications, which are needed to be addressed before surgical implantation. In this investigation, first we made a rough and porous structure on the surface of an AZ91 magnesium alloy substrate through the micro–arc oxidation (MAO) technique. The MAO layer not only can act as an intermediate layer, but it has the capability to improve the degradation and in vitro bioactivity properties of the substrate. In the next step, we deposited the nanostructured diopside coating by employing electrophoretic deposition (EPD) method on the top of MAO layer. We concluded that both the degradation resistance and the in vitro bioactivity of biodegradable magnesium alloy were improved by our surface treatment. The image below depicts a surface morphology of our produced material including scanning electron microscopy (a) and laser scanning microscopy (b) images, the result of in vitro bioactivity (c) and the result of in vitro degradation (d) tests.

 

Coating of biodegradable magnesium alloy bone implants using nanostructured diopside (CaMgSi2O6)- global medical discovery

 

 

 

 

 

 

 

 

 

 

 

Applied Surface Science, Volume 288, 2014, Pages 130-137.
Mehdi Razavi, Mohammadhossein Fathi, Omid Savabi, Batoul Hashemi Beni, Seyed Mohammad Razavi, Daryoosh Vashaee, Lobat Tayebi.

Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran and

Dental Materials Research Center, Isfahan University of Medical Sciences, Isfahan, Iran and

Torabinejad Dental Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan 81746-73461, Iran and

Department of Anatomical Sciences and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan 81746-73461, Iran and

School of Dentistry, Isfahan University of Medical Sciences, Isfahan 81746-73461, Iran and

School of Materials Science and Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106, USA and

School of Electrical and Computer Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106, USA and

School of Chemical Engineering, Oklahoma State University, Stillwater, OK 74078, USA.

Abstract

Magnesium alloys with their biodegradable characteristic can be a very good candidate to be used in orthopedic implants. However, magnesium alloys may corrode and degrade too fast for applications in the bone healing procedure. In order to enhance the corrosion resistance and the in vitro bioactivity of a magnesium alloy, a nanostructured diopside (CaMgSi2O6) film was coated on AZ91 magnesium alloy through combined micro-arc oxidation (MAO) and electrophoretic deposition (EPD) methods. The crystalline structures, morphologies and compositions of the coated and uncoated substrates were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy. Polarization, electrochemical impedance spectroscopy, and immersion test in simulated body fluid (SBF) were employed to evaluate the corrosion resistance and the in vitro bioactivity of the samples. The results of our investigation showed that the nanostructured diopside coating deposited on the MAO layer increases the corrosion resistance and improves the in vitro bioactivity of the biodegradable magnesium alloy.

 

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