Supported Electrospun 3D structure

Fibers, with their large length to diameter aspect ratio and low stiffness, are individually too weak to be self supporting. Therefore, 3D forms of electrospun fibers are made out of bundles of fibers or are supported by other means. In this article, we will describe how electrospun 3D structures have been constructed with the assistance of other supporting material or structure.

A supporting structure may be used to hold the electrospun fibers in a 3D spatial form for its application. Zhou et al (2018) used a trough collector comprising of a flat base and slanted walls to gather electrospun fibers along the depth of the collector. The collected fibers were aligned wall to wall to form a 3D structure supported by the walls. Fibroblasts cultured on this supported structure were found to be distributed throughout the fibrous matrix and aligned according to the fiber orientation. In this case, the supporting structure purpose is to hold the electrospun fibers in a 3D spatial form only while allowing the cultured cells to populate the scaffold. In most other forms, the supporting material is combined with the electrospun fibers as a whole scaffold.

Trough collector setup to support electrospun 3D structure [Zhou et al 2018].

3D printing has gained popularity due to the ability to create customised structures from bottom up. However, it is difficult to create nano-struts using this method. To improve cell adhesion and proliferation on the scaffold constructed using 3D printing or rapid prototyping technique, electrospun nanofibers have been incorporated into the scaffold during construction. The 3D plotting technique where molten polymer is used to eject strands of microfibers to build up a scaffold is commonly used in combination with electrospinning. When a deck of microfibers is built, nanofibers are deposited on the surface before the next layer of microfibers is added on. This way, a whole scaffold consisting of microfibers and nanofibers is constructed.

Combining electrospinning with Rapid Prototyping process

In certain cases, the supporting material may gain mechanical strength from having electrospun fibers. Hydrogel can be made easily into a 3D block. However, it lacks mechanical strength since it is mostly filled with water. Incorporation of nanofibers into hydrogel has been shown to improve the mechanical properties of the hydrogel [Kai et al 2012; Visser et al 2015; Liu et al 2014] and the presence of nanofibers may also potentially improve or influence cell activity in the resultant composite [Yang et al 2011]. To create a uniform composite of electrospun fibers and hydrogel, electrospinning and electrospraying of hydrogel can be carried out simultaneously. This will progressively build up a hybrid structure [Ekaputra et al 2008].