Contents lists available at ScienceDirect Corrosion Science journal homepage: www.elsevier.com/locate/corsci Study of dynamic degradation behaviour of porous magnesium under physiological environment of human cancellous bone Amir Putra Md Saad a,b , Ardiyansyah Syahrom a,b, ⁎ a Department of Applied Mechanics and Design, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia b Sports Innovation and Technology Centre (SITC), Institute of Human Centred and Engineering (IHCE), Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia ARTICLE INFO Keywords: Dynamic immersion test Cyclic loading Physiological activities Degradation rate Porous magnesium ABSTRACT This study analyse the effect of integrating of physiological environment of human cancellous bone as shown by different level of cyclic compressive on the degradation behaviour of porous magnesium under dynamic im- mersion for bone scaffold applications. The porous magnesium (30%, 41% and 55% of porosity) were immersed in simulated body fluid (SBF) with flowrate 0.0025 ml/min while having dynamic loading (1000 με, 2000 με and 3500 με) for 24, 48 and 72 h. The influenced integrating both boundaries have increased the relative weight loss and degradation rate as high as 61.56% and 93.67%, respectively as compared to dynamic immersion test only. 1. Introduction Mechanical loading induced by the physiological activities is known to be the key factor in regulating bone tissue mechanism of adaptation and formation [1]. Both mechanical stimulation of fluid flow passing through cancellous bone structure and substrates strain generated by the external forces were identified as the physical stimulus that trig- gered the bone cells respond encouraging for bone modelling and re- modelling [2,3]. Currently, biodegradable metals have been suggested for bone scaffold applications due to their mechanical properties better for load bearing applications [4–7]. The degradation behaviour of biodegradable metals are often depending on the measurement setup and environment type used to assess their potential for biomedical implant applications [8]. Bone scaffolds made of biodegradable metals are required to have porous structure which are allowing the tissues interlocking, cell migration and nutrients transport and osteo-integra- tion with host tissues replaced [9]. Once the bone scaffolds implanted, it will prone to the mechanical stimuli from the host tissue. Therefore, the stimulus boundary of fluid flow and cyclic motion of bone strain are necessary to consider simultaneously in assessing the degradation of biodegradable metals for bone scaffolds application. In contrast to the investigations rarely to Fe-based and newly in- troduced Zn-alloys, Mg and its alloys have most considered biode- gradable metals for potential bone scaffold applications [8,10–16]. Mg have exciting characteristics of atypically lightweight metal with a density of 1.74 g/cm 3 [17]. Mg hold interesting mechanical property closed to human bone, their Young’s modulus is 41–45 GPa and cortical bone is 3–23 GPa [18,19]. Mechanical property of Mg can be regulated and controllable precisely by constructing a porous structure to obtain closely match of cancellous bone Young’s modulus of 0.01–3.0 GPa [20]. Mg is easily to be founded in human bone tissue since its function is essential for human metabolism [21]. It is stored in bone tissue al- most half from the total physiological and fourth most considerable cation with 1 mol of Mg per 70 kg of adult body [10]. Due to their ionic naturally presence in human body with significant functional roles have facilitated the Mg-based scaffolds to serve as biocompatible, osteo- conductive and osteo-integration with surrounding tissues [22]. More- over, from bioactivity point of view, magnesium has a stimulatory ef- fect to bone growth due to the formation of bone-apatite like hydro- xyapatite crystal which is favourable for bone strength [23–25]. Cancellous bone remodelling is continuously occur by the couple actions of osteoclasts and osteoblasts during resorption and formation process. The osteocytes are to be known as the orchestrator in bone remodelling process that initiate the cues and triggered for bone re- sorption and formation [26]. The mechanical loading from the cyclic motion of physiological activities is the regulator mechanism that excite the mechano sensitive of osteocytes [27]. The changes in mechanical stimuli which produced by the mechanical stresses is transduced by osteocytes into chemical signal that triggered the cellular response governing the bone modelling and remodelling [26,28]. During the physical routine activity such as walking, the pressure difference cre- ated have causes the bone marrow (home of progenitor cells) flow passing through the cancellous bone structure ranges from 0.0072–1.67 ml/min [29–33]. The changes in hydrostatic pressure is https://doi.org/10.1016/j.corsci.2017.10.026 Received 11 November 2016; Received in revised form 17 October 2017; Accepted 20 October 2017 ⁎ Corresponding author at: Sport Innovation and Technology Centre (SITC), Institute of Human Centered Engineering (IHCE), Universiti Teknologi Malaysia, Johor Baharu, Malaysia. E-mail address: ardiyans@gmail.com (A. Syahrom). Corrosion Science xxx (xxxx) xxx–xxx 0010-938X/ © 2017 Elsevier Ltd. All rights reserved. Please cite this article as: Md Saad, A.P., Corrosion Science (2017), http://dx.doi.org/10.1016/j.corsci.2017.10.026