Assessment of Cytotoxicityicity of Magnesium Oxide and Magnesium Hydroxide Nanoparticles using the Electric Cell-Substrate Impedance Sensing  
[PERSON]  
1 Department of Energy and Environmental Systems, North Carolina Agricultural and Technical State University, Greensboro, NC 27411, USA; [EMAIL_ADDRESS]
2 Engineering Research Center for Revolutionized Metallic Biomaterials, North Carolina Agricultural and Technical State University, Greensboro, NC 27411, USA; [EMAIL_ADDRESS] (Y.K.); [EMAIL_ADDRESS] (J.S.)  
1 Department of Energy and Environmental Systems, North Carolina Agricultural and Technical State University, Greensboro, NC 27411, USA; [EMAIL_ADDRESS]  
2 Engineering Research Center for Revolutionized Metallic Biomaterials, North Carolina Agricultural and Technical State University, Greensboro, NC 27411, USA; [EMAIL_ADDRESS] (Y.K.); [EMAIL_ADDRESS] (J.S.)  
3 Department of Chemical, Biological and Bioengineering, North Carolina Agricultural and Technical State University, Greensboro, NC 27411, USA;  
4 Department of Animal Sciences, North Carolina Agricultural and Technical State University, Greensboro, NC 27411, USA; [EMAIL_ADDRESS] (J.S.)  
5 Department of Mechanical Engineering, North Carolina Agricultural and Technical State University, Greensboro, NC 27411, USA; [EMAIL_ADDRESS] (J.S.)  
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understand the cytotoxicity of the possible corrosion products for the future development of innovative Mg-based alloys in orthopedics [7].  
Magnesium (Mg\({}^{2+}\)) is the most important bivalent ion associated with the physiological functions of the body and participates actively in maintaining the cellular homeostasis [8; 9; 10]. Magnesium partakes in more than 300 biochemical reactions, mostly associated with the regulation of ion channels, intracellular signaling, and oxidative phosphorylation [11]. Studies suggest that approximately 53% of total body magnesium is stored in the bones [12; 13; 14; 15; 16; 17]. Deficiency of magnesium affects the metabolism of the skeleton, which inhibits bone growth and formation of new osteoblast cells, resulting in bone brittleness [8; 18; 19; 20; 21; 22; 23; 24; 25; 26; 27; 28]. There are many study reports on Mg-based biodegradable orthopedic implants; however, the real-time concentration-based toxicity of the corrosion products in the form of magnesium oxide (MgO) and magnesium hydroxide (Mg(OH)\({}_{2}\)) nanoparticles (NPs) that might be released during the implant degradation process is not known.  
In this study, we assessed the cytotoxicity of randomly selected different concentrations (0, 1, 5, 10, and 50 mM) of MgO/Mg(OH)\({}_{2}\) NPs in hFOB 1.19 cells [7] using a real-time electric cell-substrate impedance sensing (ECIS) system. With this ECIS system, cell adhesion and proliferation have been evaluated quantitatively by the generated impedance relative to the time to measure the cytotoxicity. Studies suggest that bone hemostasis is affected by the pH [29]; therefore, this study also assessed the change in the pH to measure the cytotoxicity in hFOB 1.19 cells in response to the different concentrations of MgO/Mg(OH)\({}_{2}\) NPs. As an outcome of this novel real-time in vitro ECIS study, we report our findings for an allowable concentration of MgO/Mg(OH)\({}_{2}\) NPs that might be released from Mg-based biodegradable alloys for its applications in future in vivo studies of orthopedic implants.