Expanding Two-Dimensional Electrospun Nanofiber Membranes in the Third Dimension By a Modified Gas-Foaming Technique

Abstract

Electrospun nanofibers have shown great potential as scaffolds for regenerative medicine because of its biomimicry. However, traditional two-dimensional electrospun nanofiber mats inhibit their applications due to the dense structure and lack of effective cell infiltration. Herein, we report a new method of expanding electrospun nanofiber mats in the third dimension using a modified gas-foaming technique. The resulted nanofiber scaffolds show layered structures with controllable gap widths and layer thicknesses on the order of microns. Expanded nanofiber scaffolds possess significantly higher porosity than traditional two-dimensional nanofiber membranes, while simultaneously maintaining nanotopographic cues. The distributions of gap widths and layer thicknesses are directly dependent on the processing time of nanofiber mats within the gas bubble forming solution. In vitro testing demonstrates robust cellular infiltration and proliferation within expanded nanofiber scaffolds as compared to limited cellular proliferation on the surface of traditional nanofiber mats. Importantly, cell alignment was observed throughout the expanded and aligned nanofiber scaffolds after incubation for 7 days. The presented method was further applied to fabricate tubular scaffolds composed of expanded nanofibers. Together, this novel class of scaffolds holds significant promise for applications in regenerative medicine and building 3D in vitro tissue models for drug screening and biological study.

Three-dimensional nanofiber scaffolds with arrayed holes for engineering skin tissue constructs

“…4). [10,11] The nanofiber membrane was initially 0.4 mm thick and became about 4 mm thick after expansion. Figure 2 shows the morphology of a 3D nanofiber scaffold with arrayed holes.…”

“…Recently, our group has developed a modified gas-foaming technique to expand 2D nanofiber membranes in the third dimension with controlled thickness and highly porous structures. [10,11] It was also demonstrated that cells can infiltrate the expanded nanofiber scaffolds and proliferate within the nanofiber scaffolds. These promising results motivated us to fabricate a novel type nanofiber skin graft for chronic wound healing.…”

“…[13] In order to prepare a highly hydrophilic 3D nanofibrous scaffold, we punched arrayed holes throughout 2D scaffolds and then transformed 2D membranes into 3D nanofiber scaffolds using a modified gas-foaming technique. [10,11] To demonstrate the proof-ofconcept, green fluorescent protein-labeled human dermal fibroblasts (GFP-HDF) cell spheroids were prepared and seeded into the arrayed holes of 3D nanofiber scaffolds. The cell adhesion and migration were examined in vitro.…”

“…[ 10] The parameters for electrospinning were as follows: 5% PCL and gelatin at a ratio of 1 : 1 (v/v) in HFIP, a flow rate of 0.4 mL/h, an applied voltage of 18 kV, a spinneret (a 22-gage needle), and a rotating drum located 20-23 cm away. The morphology of fiber samples was examined using scanning electron microscopy (SEM) (FEI, OR).…”

“…The nanofiber mats with arrayed holes were then expanded to form 3D scaffolds using a modified gas-foaming technique following our established protocols. [10,11] Briefly, the nanofiber mats were immersed in freshly prepared 1% NaBH 4 solutions at room temperature for 5-30 min. The expanded scaffolds were then gently rinsed three times with distilled water for 10 min each and finally freeze-dried overnight.…”