In vitro bioactivity and corrosion of PLGA/hardystonite composite-coated magnesium-based nanocomposite for implant appli
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In vitro bioactivity and corrosion of PLGA/hardystonite composite-coated magnesium-based nanocomposite for implant applications Mahmood Razzaghi, Masoud Kasiri-Asgarani, Hamid Reza Bakhsheshi-Rad, and Hamid Ghayour Advanced Materials Research Center, Department of Materials Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran (Received: 15 December 2019; revised: 27 March 2020; accepted: 13 April 2020)
Abstract: A type of polymer/ceramic coating was introduced on a magnesium-based nanocomposite, and the nanocomposite was evaluated for implant applications. The microstructure, corrosion, and bioactivity of the coated and uncoated samples were assessed. Mechanical alloying followed by sintering was applied to fabricate the Mg–3Zn–0.5Ag–15NiTi nanocomposite substrate. Moreover, different contents of poly(lactic-co-glycolic acid) (PLGA) coatings were studied, and 10wt% of PLGA content was selected. The scanning electron microscopy (SEM) images of the bulk nanocomposite showed an acceptable homogenous dispersion of the NiTi nanoparticles (NPs) in the Mg-based matrix. In the in vitro bioactivity evaluation, following the immersion of the uncoated and coated samples in a simulated body fluid (SBF) solution, the Ca/P atomic ratio demonstrated that the apatite formation amount on the coated sample was greater than that on the uncoated nanocomposite. Furthermore, assessing the corrosion resistance indicated that the coatings on the Mg-based substrate led to a corrosion current density (icorr) that was considerably lower than that of the substrate. Such a condition revealed that the coating would provide an obstacle for the corrosion. Based on this study, the PLGA/hardystonite (HT) composite-coated Mg–3Zn–0.5Ag–15NiTi nanocomposite may be suitably applied as an orthopedic implant biomaterial. Keywords: magnesium; nanocomposite; corrosion; biocompatibility; poly(lactic-co-glycolic acid); hardystonite
1. Introduction Over the last years, researchers have been increasingly interested in biodegradable Mg alloys as significant alternative materials for implants. This is because Mg alloys offer potential solutions to today’s common issues of the biomaterials used for orthopedic applications, such as the stress shielding concerns related to conventional metallic implants and the inferior mechanical properties of the polymeric biomaterials [1–2]. Magnesium is widely accepted to be biodegradable, biocompatible, and osteoconductive [3]. Moreover, research has shown that the human body can efficiently metabolize Mg degradation products, thus preventing the requirement of a second surgery for implant elimination after tissue repair [4]. Nevertheless, multiple concerns should be considered before considering pure Mg for tissue engineering, which include the low corrosion resistance and high degradation rate. This article explores Zn and Ag for reinforcing Mg to promote its mechanical properties, corrosion resistance, and antibacterial activities in order to satisfy clinical necessities
[5–7]. Zinc contributes vitally
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