Improvement of Biodegradability, Bioactivity, Mechanical Integrity and Cytocompatibility Behavior of Biodegradable Mg Based Orthopedic Implants Using Nanostructured Bredigite (Ca 7 MgSi 4 O 16 ) Bioceramic Coated via ASD/EPD Technique MEHDI RAZAVI, 1,3,4,5 MOHAMMADHOSSEIN FATHI, 1,2 OMID SAVABI, 3 DARYOOSH VASHAEE, 5 and LOBAT TAYEBI 4,6 1 Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran; 2 Dental Materials Research Center, Isfahan University of Medical Sciences, Isfahan, Iran; 3 Torabinejad Dental Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan 81746-73461, Iran; 4 School of Materials Science and Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106, USA; 5 School of Electrical and Computer Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106, USA; and 6 School of Chemical Engineering, Oklahoma State University, Stillwater, OK 74078, USA (Received 7 May 2014; accepted 31 July 2014) Associate Editor Jennifer West oversaw the review of this article. Abstract—This research explored the influence of surface modification of AZ91 Mg alloy on the biodegradation, bioactivity, mechanical integrity and cytocompatibility of the alloy. For this purpose, a nanostructured bredigite (Ca 7 MgSi 4 O 16 ) ceramic coating was prepared on biodegrad- able AZ91 Mg alloy through anodic spark deposition and electrophoretic deposition method. The phase composition and surface morphology of the coated alloy were character- ized by X-ray diffraction, scanning electron microscope and transmission electron microscope. The properties of samples were investigated by electrochemical measurements, immer- sion test, compression examination and cell culturing. The results showed that the degradation resistance, bioactivity, mechanical integrity and cytocompatibility of biodegradable Mg alloy were improved by the anodic spark deposition and electrophorretic deposition of the nanostructured bredigite coating. Therefore, the nanostructured bredigite ceramic coating is identified as a good coating for AZ91 Mg alloy for the purpose of making biodegradable metallic orthopedic implants. Keywords—Biomaterials, Biodegradable Mg alloy, Bredigite, Coating, Biomedical applications. INTRODUCTION Metallic implants such as stainless steel, titanium, and cobalt alloy have been broadly used to repair damaged bone tissue. 30,36 Commonly used titanium and stainless steel implants as well as currently approved biodegradable polymers, ceramics and nanocomposites have major drawbacks in bone surgeries. 20,31,46 Tita- nium and stainless steel implants are associated with stress shielding phenomena particularly in pediatric and adolescent patients. 19 Moreover, these implants may need to be removed from the body after healing the in- jured bone especially if they cause allergic responses in the patients. 11,36 The post-healing surgeries are not favorable due to the inconveniences and expenses for patients. 6 Biodegradable polymers, ceramics and nanocomposites may cause adverse tissue reactions and are not suitable for load-bearing applications due to their limited mechanical strength. 18,29,36 Thus, new im- plant materials combining good mechanical strength, biodegradability and improved biocompatibility are desired to be used in orthopedic surgery. 21 Biodegradable Mg alloys—a new class of degradable biomaterials—may be promising candidates as new im- plant materials and have recently attracted much atten- tion. 24,25,32 In contrast to titanium and stainless steel implants, biodegradable Mg alloy implants do not need second surgical interventions for implant removal, and also minimize stress shielding effects due to their elastic Address correspondence to Lobat Tayebi, School of Materials Science and Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106, USA. Elec- tronic mails: mrazavi2659@gmail.com, m.razavi@ma.iut.ac.ir and lobat.tayebi@okstate.edu Annals of Biomedical Engineering (Ó 2014) DOI: 10.1007/s10439-014-1084-7 Ó 2014 Biomedical Engineering Society