Alexeev Dmitriy, Tschopp Melanie, Helgason Benedikt, Ferguson Stephen J
Institut für Biomechanik ETH Zürich Zürich Switzerland.
Collaborative Research Partners, AO Foundation Davos Switzerland.
JOR Spine. 2020 Nov 27;4(1):e1130. doi: 10.1002/jsp2.1130. eCollection 2021 Mar.
Electrospun (ES) poly(ɛ-caprolactone) (PCL) is widely used to provide critical mechanical support in tissue engineering and regenerative medicine applications. Therefore, there is a clear need for understanding the change in the mechanical response of the membranes as the material degrades in physiological conditions.
ES membranes with fiber diameters from 1.6 to 6.7 μm were exposed to in vitro conditions at 37°C in Dulbecco's modified Eagle's medium (DMEM) or dry for up to 6 months.
During this period, the mechanical properties were assessed using cyclic mechanical loading, and material properties such as crystallinity and ester bond degradation were measured.
No significant difference was found for any parameters between samples kept dry and in DMEM. The increase in crystallinity was linear with time, while the ester bond degradation showed an inverse logarithmic correlation with time. All samples showed an increase in modulus with exposure time for the first loading cycle. Modulus changes for the consecutive loading cycles showed a nonlinear relationship to the exposure time that depended on membrane type and maximum strain. In addition, the recovered elastic range showed an expected increase with the maximum strain reached. The mechanical response of ES membranes was compared to experimental tensile properties of the human annulus fibrosus tissue and an in silico model of the intervertebral disk. The modulus of the tested membranes was at the lower range of the values found in literature, while the elastically recoverable strain after preconditioning for all membrane types lies within the desired strain range for this application.
The long-term assessment under application-specific conditions allowed to establish the mechanical competence of the electrospun PCL membranes. It can be concluded that with the use of appropriate fixation, the membranes can be used to create a seal on the damaged AF.
静电纺丝（ES）聚己内酯（PCL）在组织工程和再生医学应用中被广泛用于提供关键的机械支撑。因此，明确需要了解材料在生理条件下降解时膜的机械响应变化。
将纤维直径为1.6至6.7μm的ES膜在37°C下于杜氏改良 Eagle 培养基（DMEM）中进行体外培养或干燥长达6个月。
在此期间，使用循环机械加载评估机械性能，并测量诸如结晶度和酯键降解等材料性能。
干燥保存的样品与在DMEM中的样品在任何参数上均未发现显著差异。结晶度随时间呈线性增加，而酯键降解与时间呈反对数相关。所有样品在第一个加载循环中模量随暴露时间增加。连续加载循环的模量变化与暴露时间呈非线性关系，这取决于膜的类型和最大应变。此外，恢复的弹性范围随达到的最大应变呈预期增加。将ES膜的机械响应与人类纤维环组织的实验拉伸性能以及椎间盘的计算机模拟模型进行了比较。测试膜的模量处于文献报道值的较低范围，而所有膜类型预处理后的弹性可恢复应变均在该应用所需的应变范围内。
在特定应用条件下的长期评估能够确定静电纺丝PCL膜的机械性能。可以得出结论，通过使用适当的固定方法，这些膜可用于在受损的纤维环上形成密封。
