Magnesium oxide (MgO) and hydroxide [Mg(OH) 2 ] are conventionally considered insoluble in water and stable at high temperatures. However, in this study, we found significant dissociation of MgO and Mg(OH) 2 into ions when they were immersed in different physiologically relevant solutions in the form of 20nm and 10-nm nanoparticles respectively, under standard cell culture conditions in vitro, i.e., a 37°C, 5% CO 2 /95% air, sterile, humidified environment. The change in Mg 2+ ion concentrations and pH measured in the physiologically relevant solutions (e.g., Dulbecco's modified Eagle's Medium (DMEM), simulated body fluid (SBF), relevant chloride solutions, and deionized water) confirmed their dissociation. Possible mechanisms and contributing factors for dissociation of MgO and Mg(OH) 2 nanoparticles were discussed. The evidence suggests that nucleophilic substitution of OH − by Cl − in Mg(OH) 2 is energetically unfavorable and it is more likely that Cl − plays a role in the stabilization of intermediate forms of MgO and Mg(OH) 2 as it dissociates. The pH and buffering capability of the immersion solutions might have played the most significant role in dissociation of these nanoparticles when compared with the roles of chloride (Cl − ), proteins, and different buffering agents. This article provided the first evidence on the dissociation of MgO and Mg(OH) 2 nanoparticles in physiologically relevant conditions and elucidated possible factors contributing to the observed behaviors of these nanoparticles in vitro, which is important for their potential medical applications in vivo. Keywords Magnesium oxide (MgO) nanoparticles . Magnesium hydroxide [Mg(OH) 2 ] nanoparticles . Biofluids . Dulbecco's modified Eagle's Medium (DMEM) . Simulated body fluid (SBF) . HEPES buffer . Chloride (Cl − ) solutions

Medical implants play a key role in treating bone fractures. Permanent implants are currently used for immobilization of fractures and bearing physiological loads during bone healing. After bone has healed, these implants, if not removed, often cause complications in the long run; and secondary surgeries for removing them pose additional discomfort and expenses for patients. Magnesium (Mg)-based bioresorbable implants, can potentially eliminate the need for additional surgeries by degrading safely over time in the human body. When studying the degradation behaviors of Mg-based implants , it is important to simulate physiological conditions closely, including loading. Considering that implants often carry physiological loads and mechanical stresses affect the degradation rate of Mg, a novel loading device was designed and manufactured for studying Mg degradation under load over a long period of time in a simulated body fluid. Degradation of Mg rods were investigated by immersing in a revised simulated body fluid (rSBF) for two weeks while a consistent compressive load was applied using the loading device. The results showed that the loading device provided a consistent load of 500 ± 45 N during the two weeks of immersion. Mg rods showed a significant faster degradation rate under the applied load, as demonstrated by a higher mass loss of the sample, a higher pH increase and Mg ion release in the rSBF.

In this study, Nickel Zinc Ferrite was prepared using the co-precipitation method according to the chemical formula Ni1-xZnxFe2O4, where the values of (x = 0,0.1,0.3,0.5,0.7,0.9) respectively, the structural and magnetic properties were studied through X-ray diffraction spectroscopy. FESEM showed the porosity and distribution of the homogeneous nanoparticles roughly, also its particle size. The vibration sample Magnetometer (VSM)was used to study magnetic properties, and the Fourier transform infrared (FTIR) spectra were measured in the range of 400-4000 cm−1. Magnetic nanoparticles effect on contrast factors in magnetic resonance imaging (MRI) images was studied, it showed Good and robust imaging technique for diagnosis and post-treatment evaluation for a wide range of diseases. MRI contrast can be enhanced by using negative or positive contrast agents, resulting in clearer (T1-weighted) or darker (T2-weighted) images, respectively, with super-magnetic nanoparticles yielding T2 contrast agents widely used in molecular imaging applications and cellular. As most of the work in this field focuses on the acquisition of biological species using nanoparticles, which in turn will improve the magnetic properties that lead to higher imaging.