Metal–electrolyte solution dual-mode electrospinning process for in situ fabrication of electrospun bilayer membrane

Abstract

Though an electrospun bilayer membrane composed of two different layers of aligned and random nanofiber membranes has shown great potential in the tissue engineering field due to its excellent mechanical and biological functionalities, its previous fabrication processes have been inevitably relied on manual integration or enabled to produce only limited types of bilayer membranes. Here, we report a novel metal–electrolyte solution dual-mode electrospinning process, named M-ELES, for the in situ fabrication of an electrospun bilayer membrane based on a metal-electrolyte solution switchable collector. The switchable collector enabled to not only deposit random nanofibers directly over the pre-existed aligned nanofiber layer in an in situ manner but also integrate the aligned and random nanofiber layers, by an on-demand switch from the metal collector to the electrolyte solution collector. The electrolyte solution collector was found to facilely discharge excessive positive electric charges retained on the deposited nanofibers, thereby maintaining the efficiency in the random nanofiber deposition by reducing the electrostatic repulsion between the deposited and the coming nanofibers. In addition, M-ELES provided a controllability of each layer by the on-demand switch of the grounded collector and thus could produce the electrospun bilayer membranes with diverse physical and mechanical properties, including spatial orientation and fiber density of the aligned nanofiber layer as well as thickness, elastic moduli, and maximum tensile load of the bilayer membrane. As an example of biomedical application, in vitro wound healing assay using NIH3T3 fibroblast cells demonstrated that the electrospun bilayer membrane promoted wound coverage by the cells through topographical guidance of the aligned nanofiber layer while providing mechanical support for the aligned nanofibers by the random nanofiber layer.