In vivo and in vitro study of resorbable magnesium wires for medical implants:Mg purity,surface quality,Zn alloying and polymer coating

Magnesium is an excellent material in terms of biocompatibility and its corrosion products can serve as an active source for new bone formation.However,localized corrosion and H_(2)generation limit the potential of Mg-based implants.Utilizing low-alloyed Mg-Zn wires can strongly reduce problems with large H_(2)bubbles and improve the mechanical properties considerably while maintaining excellent long-term biocompatibility.Acidic pickling and a polymer coating can be effectively used to lower the rate of in vivo degradation.In this work,microstructural,mechanical,and in vitro characterization of 250μm and 300μm extruded wires made from ultra-pure Mg,commercially pure Mg,Mg-0.15Zn,Mg-0.4Zn and Mg-1Zn was performed.Additionally,Mg-0.4Zn wires together with a variant coated with a copolymer of L-lactide andε-caprolactone were tested in vivo on artificially damaged Wistar rat femurs.Based on the observed Mg-induced osteogenesis,polymer-coated Mg wires with a small addition of Zn are a perspective material for bone-support applications,such as cerclage and fixation wires.

直接挤压成形生物医用镁合金细丝（英文）

生物可降解丝可为各种生物医学应用提供承重支撑,是目前生物材料研究的新趋势。通过直接挤压制备出直径为250μm的99.92%镁丝,挤压比达1:576。单个加工步骤的总施加应变为6.36。挤压温度为230~310℃,挤压速度为0.2~0.5 mm/s。得到的金属丝具有良好的力学性能,其力学性能随挤压参数的变化而变化。室温下最大真拉应力可达228 MPa,塑性可达13%。结果表明,单步直接挤压法是一种有效的生产具有足够性能的生物医用镁丝的方法。断口分析表明,镁丝的失效可能与夹杂物(如MgO颗粒)密切相关。由于挤压温度低而导致的晶粒尺寸细小,是影响镁丝拉伸性能的主要参数。