Patterning Of Electrospun Nanofibrs For The Constuction Of Macroporous Scaffolds For Tissue Engineering

Electrospinning has received increasing attention in the tissue engineering®enerative medicine community due to its capability of making biomimetic nanofibrous scaffolds for engineering a variety of tissues. However, one of the major problems with electrospun nanofibrous scaffolds is that the densely arranged nanofibers and small pores (or interstices) between the ultrafine fibers would inhibit proper infiltration of the cells and consequently may prevent tissue regeneration in vivo. To address this challenge, in recent years many concepts or strategies applicable at the electrospinning procedures have been devised to enlarge pore size of the electrospun scaffolds. However, the various approaches devised to fabricate macroporous patterning of electrospun nanofibrous mats still have several insufficiencies. In this study, electrospun nanofibrous mats with different macroporous patterned architectures were obtained by properly designing the collectors with surface topography and/or structural patterns to realize defined nanofiber deposition. And then the nanofibrous mats are stacked layer by layer to form a3D structure. This method could provide an innovative solution to the widely recognized cellular infiltration problem associated with electrospun nanofibrous scaffolds.This paper firstly report on generation of spatially defined nanofibrous patterns by direct deposition of electrospun nanofibers onto a variety of insulating substrates. It was found that topographical features of different non-conducting substrates could be readily replicated by the electrospun nanofibers of interest. To elucidate the underlying mechanism of nanofiber patterning, we have systematically studied effects of the surface topography of non-conducting substrate (in particular the protrusion) on the nanofiber deposition and assembly. Results from experiments and electric field simulation, indicated that under the strong electric field the insulating substrates can be polarized, which could consequently affect the distribution of the original electric field. For particular non-conductive substrates with small mesh sizes or sufficient thickness, surface topography of the dielectric substrate may play a key role in determining the deposition and the arrangement of electrospun fibers. In addition, parameters that could influence the fineness of nanofibrous patterns have also been investigated. This contribution is believed to warrant further scientific understanding on the patterning mechanism of electrospun nanofibers, and to allow for design of specific and complex non-conductive substrate collectors for easy generation of patterned nanofibrous architectures, applicable in a variety of areas such as tissue engineering scaffolds.A biodegradable polymer hybrid of gelatine (Gt)/polycaprolactone (PCL) was chosen as a prototypical material for preparing macroporous patterning of electrospun nanofibrous mats. Then the mats were stacked layer by layer to form a3D macroporous scaffold. In the same way, non-woven scaffolds were prepared as control group. The effects of3D macroporous structure on the cellular infiltration were investigated. SEM results suggested that the3D macroporous scaffold possessed macroporous structures, which still remained the macroporous structures after stacking layer by layer; the electrospun nanofibers preferably deposited and assembled onto the pore wall section. Porosity results suggested that the porosity of the3D macroporous scaffold was higher than the non-woven scaffolds. Moreover, there was no significance difference on the swelling ratio of these two kinds of scaffolds. Mechanical test results showed that, due to the introduction of macroporous structure, mechanical properties of macroporous scaffolds were lower than that of the non-woven scaffolds. SEM results revealed the morphology of porcine articular cartilage cells on3D macroporous scaffold and non-woven scaffold. It is found that the cell can grow into the3D macroporous scaffold. The proliferation situation of cartilage cells on the scaffolds were assayed by CCK-8. By the vertical section of scaffolds, SEM results revealed that the cartilage cells can grow into the3D macroporous scaffold; through immunofluorescence staining, fluorescence microscope results suggested that the cartilage cells grow into the3D macroporous scaffold and connected together. In contrast, most cells only proliferated on the surface of the non-woven scaffold with few cells infiltration into the scaffold. At the same time, the depth of cellular infiltration on the3D macroporous scaffold is much higher than that of the non-woven scaffold. These results indicate that, compared to non-woven scaffold,3D macroporous scaffold could promote cellular infiltration, namely by the3D macroporous structure the cells could migrate and grow into the nanofibrous scaffolds. The combined results of the physicochemical and biological studies indicated that the3D macroporous scaffolds exhibited good potential and biocompatibility for cartilage tissue engineering applications.