Medical Engineering Design and Innovation Centre, Cork Institute of Technology, Cork, Ireland.
J Mater Sci Mater Med. 2009 Nov;20(11):2207-14. doi: 10.1007/s10856-009-3789-y. Epub 2009 May 28.
Controlled delivery of active ions from biomaterials has become critical in bone regeneration. Some silica-based materials, in particular bioactive glasses, have received much attention due to the ability of their dissolution products to promote cell proliferation, cell differentiation and activate gene expression. However, many of these materials offer little therapeutic potential for diseased tissue. Incorporating trace elements, such as zinc and strontium, known to have beneficial and therapeutic effects on bone may provide a more viable bone graft option for those suffering from metabolic bone diseases such as osteoporosis. Rational compositional design may also allow for controlled release of these active ions at desirable dose levels in order to enhance therapeutic efficacy. In this study, six differing compositions of calcium-strontium-sodium-zinc-silicate (Ca-Sr-Na-Zn-Si) glass bone grafts were immersed in pH 7.4 and pH 3 solutions to study the effect of glass composition on zinc and strontium release in a normal and extreme physiological environment. The zinc release levels over 30 days for all zinc-containing glasses in the pH 7.4 solution were 3.0-7.65 ppm. In the more acidic pH 3 environment, the zinc levels were higher (89-750 ppm) than those reported to be beneficial and may produce cytotoxic or negative effects on bone tissue. Strontium levels released from all examined glasses in both pH environments similarly fell within apparent beneficial ranges--7.5-3500 ppm. Glass compositions with identical SrO content but lower ZnO:Na(2)O ratios, showed higher levels of Sr(2+) release. Whereas, zinc release from zinc-containing glasses appeared related to ZnO compositional content. Sustainable strontium and zinc release was seen in the pH 7.4 environment up to day 7. These results indicate that the examined Ca-Sr-Na-Zn-Si glass compositions show good potential as therapeutic bone grafts, and that the graft composition can be tailored to allow therapeutic levels of ions to be released.
从生物材料中控制活性离子的释放对于骨再生至关重要。一些基于硅的材料，特别是生物活性玻璃，由于其溶解产物能够促进细胞增殖、细胞分化和激活基因表达，因此受到了广泛关注。然而，许多这类材料对于患病组织几乎没有治疗潜力。掺入锌和锶等微量元素，已知这些元素对骨骼具有有益和治疗作用，可能为患有代谢性骨病（如骨质疏松症）的患者提供更可行的骨移植物选择。合理的组成设计还可以控制这些活性离子在理想剂量水平下的释放，以增强治疗效果。在这项研究中，六种不同组成的钙-锶-钠-锌-硅（Ca-Sr-Na-Zn-Si）玻璃骨移植物被浸入 pH 7.4 和 pH 3 的溶液中，以研究玻璃组成对正常和极端生理环境中锌和锶释放的影响。在 pH 7.4 溶液中所有含锌玻璃在 30 天内的锌释放水平为 3.0-7.65ppm。在更酸性的 pH 3 环境中，锌水平更高（89-750ppm），高于被认为有益的水平，可能对骨组织产生细胞毒性或负面作用。在两种 pH 环境中，所有被检测玻璃释放的锶水平也都在明显的有益范围内--7.5-3500ppm。具有相同 SrO 含量但 ZnO:Na(2)O 比例较低的玻璃组成表现出更高的 Sr(2+)释放水平。而含锌玻璃的锌释放似乎与 ZnO 组成含量有关。在 pH 7.4 环境中可持续释放锶和锌，直到第 7 天。这些结果表明，所研究的 Ca-Sr-Na-Zn-Si 玻璃组成具有作为治疗性骨移植物的良好潜力，并且可以通过调整移植物组成来控制离子的释放水平以达到治疗效果。
