Department of Biomedical Engineering, Texas A&M University, College Station, Texas 77843-3120, USA.
Tissue Eng Part C Methods. 2013 Oct;19(10):810-9. doi: 10.1089/ten.TEC.2012.0671. Epub 2013 Apr 10.
Electrospinning is a popular technique to fabricate tissue engineering scaffolds due to the exceptional tunability of fiber morphology that can be used to control scaffold mechanical properties, degradation rate, and cell behavior. Although the effects of modulating processing or solution parameters on fiber morphology have been extensively studied, there remains limited understanding of the impact of environmental parameters such as humidity. To address this gap, three polymers (poly(ethylene glycol) [PEG], polycaprolactone [PCL], and poly(carbonate urethane) [PCU]) were electrospun at a range of relative humidities (RH = 5%-75%) and the resulting fiber architecture characterized with scanning electron microscopy. Low relative humidity (< 50%) resulted in fiber breakage for all three polymers due to decreased electrostatic discharge from the jet. At high relative humidity (> 50%), three distinct effects were observed based on individual polymer properties. An increase in fiber breakage and loss of fiber morphology occurred in the PEG system as a result of increased water absorption at high relative humidity. In contrast, surface pores on PCL fibers were observed and hypothesized to have formed via vapor-induced phase separation. Finally, decreased PCU fiber collection occurred at high humidity likely due to increased electrostatic discharge. These findings highlight that the effects of relative humidity on electrospun fiber morphology are dependent on polymer hydrophobicity, solvent miscibility with water, and solvent volatility. An additional study was conducted to highlight that small changes in molecular weight can strongly influence solution viscosity and resulting fiber morphology. We propose that solution viscosity rather than concentration is a more useful parameter to report in electrospinning methodology to enable reproduction of findings. In summary, this study further elucidates key mechanisms in electrospun fiber formation that can be utilized to fabricate tissue engineering scaffolds with tunable and reproducible properties.
静电纺丝是一种制备组织工程支架的常用技术，因为纤维形态的特殊可调性可以用来控制支架的机械性能、降解率和细胞行为。尽管已经广泛研究了调节加工或溶液参数对纤维形态的影响，但对于环境参数（如湿度）的影响仍知之甚少。为了解决这一差距，我们将三种聚合物（聚乙二醇[PEG]、聚己内酯[PCL]和聚碳酸酯尿烷[PCU]）在一系列相对湿度（RH=5%-75%）下进行静电纺丝，并通过扫描电子显微镜对得到的纤维结构进行了表征。对于所有三种聚合物，低相对湿度（<50%）会导致纤维断裂，这是由于射流的静电释放减少。在高相对湿度（>50%）下，根据聚合物的特性观察到三种不同的效应。由于在高相对湿度下吸收了更多的水，PEG 体系中的纤维断裂和纤维形态的丧失增加。相比之下，PCL 纤维表面出现了孔隙，据推测是通过蒸气诱导相分离形成的。最后，在高湿度下，PCU 纤维的收集减少，可能是由于静电释放增加。这些发现表明，相对湿度对静电纺丝纤维形态的影响取决于聚合物的疏水性、溶剂与水的混溶性和溶剂的挥发性。我们还进行了一项额外的研究，以强调分子量的微小变化会强烈影响溶液的粘度和最终的纤维形态。我们建议在静电纺丝方法中报告溶液粘度而不是浓度，这是一个更有用的参数，以实现结果的重现。总之，这项研究进一步阐明了静电纺丝纤维形成的关键机制，可用于制造具有可调谐和可重复性能的组织工程支架。
