CERAMICS INTERNATIONAL Available online at www.sciencedirect.com Ceramics International 40 (2014) 15149–15158 Biodegradation assessment of nanostructured fluoridated hydroxyapatite coatings on biomedical grade magnesium alloy Ramin Rojaee a,b,c,n , Mohammadhossein Fathi a,b , Keyvan Raeissi c , Ali Sharifnabi a,d a Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran b Dental Materials Research Center, Isfahan University of Medical Sciences, Isfahan, Iran c Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran d Biomaterials Group, Department of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran 16844, Iran Received 2 June 2014; received in revised form 28 June 2014; accepted 28 June 2014 Available online 5 July 2014 Abstract The challenges associated with managing Mg degradation rate demand novel technologies to ensure its biological safety and reliability. Here, fluoridated hydroxyapatite nanopowders with different degrees of fluoridation were coated on microarc oxidized AZ91 magnesium alloy via the electrophoretic deposition method. Zeta potential and conductivity monitoring techniques were employed to offer appropriate conditions for the coatings. The bio-corrosion process and the associated mineralization were interpreted during the immersion in simulated body fluid solution. Based on the results, the 25% fluorine substituted hydroxyapatite coating on microarc-treated AZ91 implant was proposed to stimulate bone ingrowth in a minor invasive behavior and without post-operative complications during its lifespan. & 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Keywords: Bio-degradable implants; Magnesium; Fluor-hydroxyapatite; Electrophoretic deposition 1. Introduction A significant increase in the amount of research has been undertaken across the globe on bio-degradable and bio- absorbable materials, particularly in the fields of bone fractures, osteoporosis, scoliosis and other musculoskeletal problems over the past several years, where the use of metallic materials are still the mainstream research topic in orthopedic implants [1]. The metals commonly used in biomaterial applications are titanium, 316L stainless steel, platinum–iridium alloy, tantalum, nickel–titanium, cobalt–chromium alloy, and magnesium (Mg) alloy [2,3]. Aside from the conventional metallic materials, designing and preparing of Mg based alloys have been the subject of extensive study in traumatological devices such as bio-degradable stents, rods, fracture plates, pins and screws during the last decade [4]. The importance of Mg in inducing osteogenesis, angiogenesis and neovascularization is well docu- mented [5]. Low dietary Mg intake may be a risk factor for osteoporosis [6]. Recently, Bangcheng et al. [7]showed that Mg is a potential biomaterial with antibone cancer properties because of releasing hydrogen (H 2 ) upon degradation reaction in human body. As reported, H 2 has been suggested as a selective antioxidant and it can effectively scavenge free radicals. Free radicals play an important role in the occurrence and metastasis of cancer [7]. Additionally, Mg 2 þ ions stimulate bone growth by enhancing osteoblast and osteoclast activities [6]. Owing to the uncontrolled release pattern of the corrosion products and systemic side effects in musculoskeletal tissues, Mg presents some drawbacks in medical applications [8]. Too rapid degradation of Mg alloys may lead to an undesirable biological response due to the serious H 2 evolution and local alkalization of the body fluid [9]. A number of contributions have touched upon the development of Mg based alloy to undergo a controlled degradation during new tissue regeneration period [10]. Besides improving the biodegradation of Mg alloys, www.elsevier.com/locate/ceramint http://dx.doi.org/10.1016/j.ceramint.2014.06.129 0272-8842/& 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved. n Corresponding author at: Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran. Tel.: þ 98 9119901024; fax: þ 98 3113912752. E-mail address: raminrojaee@aim.com (R. Rojaee).