Morphological evaluation of electrospun polycaprolactone fibers depending on the type of solvent

ABSTRACT Recently, tissue engineering strategies for wound and burn treatment focuses on the use of nanostructures biomaterials capable of facilitating skin regeneration and wound healing. One of the processes used to obtain this type of biomaterial is electrospinning. This process allows to producing films composed of polymeric nanofibers from a polymeric solution and thus, mimics the skin extracellular matrix. Among the most commonly used polymers, polycaprolactone (PCL) can be highlighted due to its solubility in several types of solvents. This study aimed to evaluate the effect of electrical conductivity of different solvents on morphology of electrospun PCL fibers. The influence of molar mass and viscosity of solution as well as flow rate and voltage was also investigated. Acetic acid (AC), formic acid (AF), chloroform (CLO), dichloromethane (DCM) and dimethylformamide (DMF) were used as solvents. Fibers with uniform diameters and defect-free, such as beads, were obtained using the DCM:DMF 70:30 (m/m) solvent system. In spite of decreasing PCL molar mass during processing, this solvent system presented the best results for PCL electrospinning. Electrical conductivity directly influenced all studied variables. When solvent systems with higher electrical conductivity value were used, lower voltage was necessary to produce defect-free fibers.

摘要
近年来，用于创伤与烧伤治疗的组织工程策略多聚焦于可促进皮肤再生与创面愈合的纳米结构生物材料的应用。静电纺丝（electrospinning）是制备这类生物材料的常用工艺之一，该工艺可通过聚合物溶液制备由聚合物纳米纤维构成的薄膜，从而模拟皮肤的细胞外基质。在常用聚合物中，聚己内酯（polycaprolactone, PCL）因可溶于多种溶剂而备受关注。
本研究旨在探究不同溶剂的电导率对静电纺丝制备的PCL纤维形貌的影响，同时考察了溶液摩尔质量、黏度以及纺丝流量与电压的作用。本实验选用乙酸（acetic acid, AC）、甲酸（formic acid, AF）、三氯甲烷（chloroform, CLO）、二氯甲烷（dichloromethane, DCM）与二甲基甲酰胺（dimethylformamide, DMF）作为溶剂。采用DCM:DMF 70:30（质量比）溶剂体系可制备得到直径均匀且无珠状缺陷等瑕疵的纤维。尽管在纺丝过程中PCL的摩尔质量会有所下降，但该溶剂体系仍是PCL静电纺丝的最优选择。
电导率对所有考察变量均有直接影响：当采用电导率更高的溶剂体系时，制备无瑕疵纤维所需的电压更低。