Needleless Electrospinning of PAN Nanofibre Mats

Polyacrylonitrile (PAN) is one of the few waterproof polymers that can be spun from relatively safe solvents, facilitating the use of PAN nanofibre mats in diverse medical and biological applications, such as tissue engineering and cell growth promotion. PAN, on the other hand, is significantly harder to use in electrospinning than polyethylene glycol and other water-soluble biopolymers. In our recent study, we thus varied spinning and material parameters for PAN dissolved in dimethyl sulfoxide (DMSO) and studied spinnability, as well as the resulting nanofibre mat morphologies, using a Nanospider Lab needleless electrospinning machine. The results were examined using confocal laser scanning microscopy and atomic force microscopy. On the one hand, the images show that the relative humidity in the chamber plays a significant role: excessively high values may cause undesired fibre connections between oppositely charged parts of the Nano-spider, creating cotton-candy-like structures that impede the free flow of fibres to the substrate and thus the creation of the desired nanofibre mat. On the other hand, the PAN concentration in the spinning solution is crucial: similar to the electrospinning of other (bio-) polymers, no fibres are formed if the polymer concentration is too low. Third, the PAN material itself affects the nanofibre creation process, illustrating that not every PAN is ideal for electrospinning.