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，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高分子纳米纤维构成的薄膜，从而模拟皮肤的细胞外基质（extracellular matrix）。在常用的高分子材料中，聚己内酯（polycaprolactone, PCL）因可溶于多种溶剂而广受关注。本研究旨在探究不同溶剂的电导率对静电纺聚己内酯纤维形貌的影响，同时考察了溶液摩尔质量、粘度以及纺丝流量与电压的作用。实验选用乙酸（acetic acid, AC）、甲酸（formic acid, AF）、氯仿（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，m/m）的溶剂体系，可获得直径均匀且无液珠等缺陷的纤维。尽管该体系在纺丝过程中会降低聚己内酯的摩尔质量，但其仍是聚己内酯静电纺丝的最优溶剂体系。电导率直接影响所有考察的实验变量：当使用电导率更高的溶剂体系时，制备无缺陷纤维所需的电压更低。