Kim Doyoon, Lee Byeongdu, Marshall Brittany P, Jang Eunyoung, Thomopoulos Stavros, Jun Young-Shin
Department of Energy, Environmental & Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States.
X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States.
ACS Appl Bio Mater. 2020 Feb 17;3(2):902-910. doi: 10.1021/acsabm.9b00979. Epub 2020 Jan 21.
Mechanical loads from physiologic activities such as walking and running generate bioelectricity in bones. By mimicking bioelectricity, external electrical stimulations have also been used therapeutically to stimulate bone-forming cells and, thus, to promote bone regeneration. However, little is known about the physicochemical mechanism(s) by which electrical stimulations drives calcium phosphate mineralization of collagen. Here, we showed that, during collagen mineralization in the absence of cells, application of pulsed electrical stimulation significantly enhanced the transport of ionic body fluid components through a micrometer-scale channel (∼100-200 μm gap space between the inner surfaces of tube-like collagen scaffolds and a cathode placed inside the collagen scaffolds). The enhanced transport of ionic precursors increased diffusion of the charged precursors from the channel to the inner collagen surface, where bone mineralization was otherwise restricted. The results indicate that pulsed electrical signals can locally accelerate the nucleation of calcium phosphate nanocrystals in or on collagen, allowing us to better control the spatial distribution of the nanocrystals at the microscale. The findings from this study provide insights into the utilization of electrical stimulation for applications such as facilitating bone-fracture healing and designing better bone-specific biomaterials.
诸如行走和跑步等生理活动产生的机械负荷会在骨骼中产生生物电。通过模拟生物电，外部电刺激也已被用于治疗，以刺激成骨细胞，从而促进骨再生。然而，关于电刺激驱动胶原蛋白磷酸钙矿化的物理化学机制，人们所知甚少。在此，我们表明，在无细胞情况下的胶原蛋白矿化过程中，施加脉冲电刺激显著增强了离子体液成分通过微米级通道（管状胶原蛋白支架内表面与置于胶原蛋白支架内的阴极之间约100 - 200μm的间隙空间）的运输。离子前体运输的增强增加了带电前体从通道到胶原蛋白内表面的扩散，而在胶原蛋白内表面，骨矿化原本受到限制。结果表明，脉冲电信号可局部加速胶原蛋白中或其表面磷酸钙纳米晶体的成核，使我们能够在微观尺度上更好地控制纳米晶体的空间分布。这项研究的结果为电刺激在促进骨折愈合和设计更好的骨特异性生物材料等应用中的利用提供了见解。
