Magnesium carbonate 500mg capsules

) shift from Ca (-6.28 ± 0.05) to Mg (-4.54 ± 0.16) ACMC endmember, can be explained by the increasing water content and changes in short-range order, as Ca is substituted by Mg in the ACMC structure. The results of this study shed light on the factors controlling ACMC solubility and its temporal stability in aqueous solutions.

Abstract licence: CC BY-NC

• Biomimetic deposited calcium carbonate coating was treated by sodium stearate. • Corrosion current density dropped 3 orders after treatment, with improved resistance. • Cell viability increased by 20% after treatment, showing a better biocompatibility. Magnesium alloy is a promising biodegradable metal material for hard tissue engineering. However, its high corrosion rate limits its application. In our previous study, we biomimetically deposited a calcium carbonate coating on the surface of magnesium alloy using siloxane induction. This calcium carbonate coating demonstrated excellent in vitro biocompatibility and provided partial protection for the magnesium alloy substrate. In this study, we further enhanced the corrosion resistance of the calcium carbonate coating by treating it with stearic acid and its derivative, sodium stearate. Electrochemical corrosion tests revealed that the sodium stearate-treated calcium carbonate coating reduced the corrosion rate by two orders of magnitude. Additionally, in vitro biocompatibility assessments showed that while the biocompatibility of the sodium stearate-treated coating was slightly reduced, it remained acceptable compared to the magnesium substrate. This study builds on our previous work and offers a promising reinforcement strategy for degradable magnesium alloys in medical applications.

Abstract licence: CC BY-NC-ND

Magnesium alloys with integration of degradability and good mechanical performance are desired for vascular stent application. Drug-eluting coatings may optimize the corrosion profiles of magnesium substrate and reduce the incidence of restenosis simultaneously. In this paper, poly (trimethylene carbonate) (PTMC) with different molecular weight (50,000 g/mol named as PTMC5 and 350,000 g/mol named as PTMC35) was applied as drug-eluting coatings on magnesium alloys. A conventional antiproliferative drug, paclitaxel (PTX), was incorporated in the PTMC coating. The adhesive strength, corrosion behavior, drug release and biocompatibility were investigated. Compared with the PLGA control group, PTMC coating was uniform and gradually degraded from surface to inside, which could provide long-term protection for the magnesium substrate. PTMC35 coated samples exhibited much slower corrosion rate 0.05 μA/cm2 in comparison with 0.11 μA/cm2 and 0.13 μA/cm2 for PLGA and PTMC5 coated counterparts. In addition, PTMC35 coating showed more stable and sustained drug release ability and effectively inhibited the proliferation of human umbilical vein vascular smooth muscle cells. Hemocompatibility test indicated that few platelets were adhered on PTMC5 and PTMC35 coatings. PTMC35 coating, exhibiting surface erosion behavior, stable drug release and good biocompatibility, could be a good candidate as a drug-eluting coating for magnesium-based stent.

Abstract licence: CC BY-NC-ND

We report the first calorimetric observations of glass transition temperatures and crystallization rates of anhydrous, amorphous calcium-magnesium carbonate using fast scanning differential scanning calorimetry. Hydrous amorphous Ca 0.95 Mg 0.05 CO 3 · 0.5H 2 O (ACMC) solid was precipitated from a MgCl 2 –NaHCO 3 buffered solution, separated from the supernatant, and freeze-dried. An aliquot of the freeze-dried samples was additionally dried at 250°C for up to 6 h in a furnace and in a high-purity N 2 atmosphere to produce anhydrous ACMC. The glass transition temperature of the anhydrous Ca 0.95 Mg 0.05 CO 3 was determined by applying different heating rates (1000–6000 K s −1 ) and correcting for thermal lag to be 376°C and the relaxational heat capacity was determined to be C p = 0.16 J/(g K). Additionally, the heating rate dependence of the temperature that is associated with the corrected crystallization peaks is used to determine the activation energy of crystallization to be 275 kJ mol −1 . A high-resolution transmission electron microscopy study on the hydrous and anhydrous samples provided further constraints on their compositional and structural states. This article is part of the theme issue 'Exploring the length scales, timescales and chemistry of challenging materials (Part 1)'.

Abstract licence: CC BY