The mechanics of PLGA nanofiber scaffolds with biomimetic gradients in mineral for tendon-to-bone repair.
The mechanics of PLGA nanofiber scaffolds with biomimetic gradients in mineral for tendon-to-bone repair.
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PLGA纳米纤维支架的机制，具有矿物质中的仿生梯度，用于肌腱对骨修复。
DOI：
10.1016/j.jmbbm.2014.08.002
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发表时间：
2014-12
影响因子：
3.9
通讯作者：
Thomopoulos, S.
中科院分区：
文献类型：
--
作者：
Lipner, J.;Liu, W.;Liu, Y.;Boyle, J.;Genin, G. M.;Xia, Y.;Thomopoulos, S.
由于界面处可能出现应力集中，不同材料的附着容易失败。成分或结构梯度的转变可以消除这些应力集中，从而使附着体变得更坚韧。柔韧肌腱和硬骨之间的界面利用羟基磷灰石矿物(“矿物”)含量的单调变化来产生机械性能的梯度，并缓解应力集中。以前模仿肌腱到骨的自然附着的努力包括在矿物中具有梯度的电纺纳米纤维聚合物支架。纳米纤维支架的矿化通常是使用模拟体液(SBF)实现的。根据SBF的具体配方，矿物形态从密集堆积的小晶体到片状晶体小花不等。尽管支架的这种矿化产生了模数的增加，但所获得的峰值模数仍然明显低于骨的模数。这些先前的经验方法缺乏对矿物形态对支架力学的影响的洞察，以及该方法最终实现接近骨的模数的可能性。在这里，我们应用了两种矿化方法来生成矿物质含量具有空间梯度的支架，并开发了量化硬化效果的方法，并在理论范围内对其进行了评估。我们询问我们开发的这两种矿化方法是否有可能实现支架的足够硬化，并测试了更光滑、更致密的矿物涂层可以达到更有效的硬化效果的假设。要验证这一假设，需要开发均一化界限并与之进行比较，以及开发估计矿物体积分数和模数空间梯度的技术。对于两种矿化策略，能量色散X射线分析表明，矿物浓度沿支架长度方向形成了线性梯度，拉曼光谱分析表明，生成的矿物是羟基磷灰石。力学测试表明，使用新方法得到的刚度梯度明显变陡。通过使用微观力学建模技术对支架进行分析，并根据我们的实验结果进行推断，我们提出了新的矿化方案具有潜在的潜力，可以达到足以促进肌腱与骨连接的修复的硬度水平。
Attachment of dissimilar materials is prone to failure due to stress concentrations that can arise at interfaces. A compositionally or structurally graded transition can dissipate these stress concentrations and thereby toughen an attachment. The interface between compliant tendon and stiff bone utilizes a monotonic change in hydroxylapatite mineral (“mineral”) content to produce a gradient in mechanical properties and mitigate stress concentrations. Previous efforts to mimic the natural tendon-to-bone attachment have included electrospun nanofibrous polymer scaffolds with gradients in mineral. Mineralization of the nanofiber scaffolds has typically been achieved using simulated body fluid (SBF). Depending on the specific formulation of SBF, mineral morphologies ranged from densely packed small crystals to platelike crystal florets. Although this mineralization of scaffolds produced increases in modulus, the peak modulus achieved remained significantly below that of bone. Missing from these prior empirical approaches was insight into the effect of mineral morphology on scaffold mechanics and on the potential for the approach to ultimately achieve moduli approaching that of bone. Here, we applied two mineralization methods to generate scaffolds with spatial gradations in mineral content, and developed methods to quantify the stiffening effects and evaluate them in the context of theoretical bounds. We asked whether either of the mineralization methods we developed holds potential to achieve adequate stiffening of the scaffold, and tested the hypothesis that the smoother, denser mineral coating could attain more potent stiffening effects. Testing this hypothesis required development of and comparison to homogenization bounds, and development of techniques to estimate mineral volume fractions and spatial gradations in modulus. For both mineralization strategies, energy dispersive x-ray analysis demonstrated the formation of linear gradients in mineral concentration along the length of the scaffolds, and Raman spectroscopic analysis revealed that the mineral produced was hydroxylapatite. Mechanical testing showed that the stiffness gradient using the new method was significantly steeper. By analyzing the scaffolds using micromechanical modeling techniques and extrapolating from our experimental results, we present evidence that the new mineralization protocol has the potential to achieve levels of stiffness adequate to contribute to enhanced repair of tendon-to-bone attachments.
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DOI：
10.1007/s10856-007-3195-2
发表时间：
2008-07-01
影响因子：
3.7
作者：
Chen, Yun;Cho, M. R.;Sun, S.
通讯作者：
Sun, S.
影响因子：
9.7
作者：
Deymier-Black, A. C.;Almer, J. D.;Dunand, D. C.
通讯作者：
Dunand, D. C.
DOI：
10.1023/b:visi.0000011205.11775.fd
发表时间：
2004-02-01
影响因子：
19.5
作者：
Baker, S;Matthews, I
通讯作者：
Matthews, I
DOI：
10.1002/jbm.b.30356
发表时间：
2006-05-01
影响因子：
3.4
作者：
Chen, Y;Mak, AFT;Li, JS
通讯作者：
Li, JS
DOI：
10.1016/j.jmbbm.2011.08.005
发表时间：
2012-01-01
影响因子：
3.9
作者：
Deymier-Black, A. C.;Almer, J. D.;Dunand, D. C.
通讯作者：
Dunand, D. C.