On the degradation behavior of magnesium, magnesium hydroxide derived coatings and magnesium containing layered double hydroxides with regard to medical applications

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Degradation rates and products of pure magnesium exposed to different aqueous media under physiological conditions

As magnesium and many of its alloys are a promising class of degradable implant materials, a thorough understanding of their degradation under physiological conditions is a key challenge in the field of biomaterial science. In order to increase the predictive power of in vitro studies, it is necessary to imitate the in vivo conditions, track the decomposition process and identify the products that form during the degradation pathway. In this in vitro study, slices of pure magnesium were exposed to Hank's Balanced Salt Solution (HBSS), Dulbecco's Modified Eagle Medium (DMEM) and simulated body fluid (SBF), respectively, under cell culture conditions, which included CO2 gassing. The series were repeated with supplements of fetal bovine serum (FBS), added to the respective media. Degradation rates, osmolality and pH were found to vary with the choice of medium and supplementation with proteins. In order to identify the crystalline degradation products, the crusts formed on the specimens were investigated via X-ray diffraction (XRD) measurements. As expected, brucite, Mg(OH)2, was found among the degradation products; interestingly, nesquehonite, Mg(HCO3)(OH)·2H2O, was found to be the dominant degradation product in this study. The experimental data are well in accordance with solubility calculations

Degradation rates and products of pure magnesium exposed to different aqueous media under physiological conditions

As magnesium and many of its alloys are a promising class of degradable implant materials, a thorough understanding of their degradation under physiological conditions is a key challenge in the field of biomaterial science. In order to increase the predictive power of in vitro studies, it is necessary to imitate the in vivo conditions, track the decomposition process and identify the products that form during the degradation pathway. In this in vitro study, slices of pure magnesium were exposed to Hank's Balanced Salt Solution (HBSS), Dulbecco's Modified Eagle Medium (DMEM) and simulated body fluid (SBF), respectively, under cell culture conditions, which included CO2 gassing. The series were repeated with supplements of fetal bovine serum (FBS), added to the respective media. Degradation rates, osmolality and pH were found to vary with the choice of medium and supplementation with proteins. In order to identify the crystalline degradation products, the crusts formed on the specimens were investigated via X-ray diffraction (XRD) measurements. As expected, brucite, Mg(OH)2, was found among the degradation products; interestingly, nesquehonite, Mg(HCO3)(OH)·2H2O, was found to be the dominant degradation product in this study. The experimental data are well in accordance with solubility calculations

Degradation rates and products of pure magnesium exposed to different aqueous media under physiological conditions

As magnesium and many of its alloys are a promising class of degradable implant materials, a thorough understanding of their degradation under physiological conditions is a key challenge in the field of biomaterial science. In order to increase the predictive power of in vitro studies, it is necessary to imitate the in vivo conditions, track the decomposition process and identify the products that form during the degradation pathway. In this in vitro study, slices of pure magnesium were exposed to Hank's Balanced Salt Solution (HBSS), Dulbecco's Modified Eagle Medium (DMEM) and simulated body fluid (SBF), respectively, under cell culture conditions, which included CO2 gassing. The series were repeated with supplements of fetal bovine serum (FBS), added to the respective media. Degradation rates, osmolality and pH were found to vary with the choice of medium and supplementation with proteins. In order to identify the crystalline degradation products, the crusts formed on the specimens were investigated via X-ray diffraction (XRD) measurements. As expected, brucite, Mg(OH)2, was found among the degradation products; interestingly, nesquehonite, Mg(HCO3)(OH)·2H2O, was found to be the dominant degradation product in this study. The experimental data are well in accordance with solubility calculations

In vitro corrosion of ZEK100 plates in Hank's Balanced Salt Solution

Background: In recent years magnesium alloys have been intensively investigated as potential resorbable materials with appropriate mechanical and corrosion properties. Particularly in orthopedic research magnesium is interesting because of its mechanical properties close to those of natural bone, the prevention of both stress shielding and removal of the implant after surgery. Methods: ZEK100 plates were examined in this in vitro study with Hank's Balanced Salt Solution under physiological conditions with a constant laminar flow rate. After 14, 28 and 42 days of immersion the ZEK100 plates were mechanically tested via four point bending test. The surfaces of the immersed specimens were characterized by SEM, EDX and XRD. Results: The four point bending test displayed an increased bending strength after 6 weeks immersion compared to the 2 week group and 4 week group. The characterization of the surface revealed the presence of high amounts of O, P and Ca on the surface and small Mg content. This indicates the precipitation of calcium phosphates with low solubility on the surface of the ZEK100 plates. Conclusions: The results of the present in vitro study indicate that ZEK100 is a potential candidate for degradable orthopedic implants. Further investigations are needed to examine the degradation behavior

Evaluating a Novel Class of Biomaterials: Magnesium-Containing Layered Double Hydroxides

Metallic magnesium and compounds such as magnesium hydroxide Mg(OH)2 have been shown to have osteoconductive properties under experimental conditions and are gaining an increasing interest in the field of degradable biomaterials. The application of the compounds as implant coatings could support implant incorporation, resulting in an increased period of use of the implants. A variety of Mg-containing Layered Double Hydroxides (Mg-LDHs) has been synthesized and examined. These materials have been tested in various in vitro and in vivo studies; the latter took place in different sites like in the middle ear or in the condyle of New Zealand White Rabbits. In the latest study newly formed bone could be found around the Mg-Al-CO3-LDH pellets, making it a promising compound for bone-healing applications.DFG/SFB/59

In vitro corrosion of ZEK100 plates in Hank's Balanced Salt Solution

Abstract Background In recent years magnesium alloys have been intensively investigated as potential resorbable materials with appropriate mechanical and corrosion properties. Particularly in orthopedic research magnesium is interesting because of its mechanical properties close to those of natural bone, the prevention of both stress shielding and removal of the implant after surgery. Methods ZEK100 plates were examined in this in vitro study with Hank's Balanced Salt Solution under physiological conditions with a constant laminar flow rate. After 14, 28 and 42 days of immersion the ZEK100 plates were mechanically tested via four point bending test. The surfaces of the immersed specimens were characterized by SEM, EDX and XRD. Results The four point bending test displayed an increased bending strength after 6 weeks immersion compared to the 2 week group and 4 week group. The characterization of the surface revealed the presence of high amounts of O, P and Ca on the surface and small Mg content. This indicates the precipitation of calcium phosphates with low solubility on the surface of the ZEK100 plates. Conclusions The results of the present in vitro study indicate that ZEK100 is a potential candidate for degradable orthopedic implants. Further investigations are needed to examine the degradation behavior.</p