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 because of 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 resulting 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.