Neuronal Racetracks: Replica Molding.

The electrospinning technique is attracting interest not just because of nanofibers, but because of the microfluidic channels and grooves that nanofibers can cast. One particularly exciting technique under development is the production of straight, parallel microgrooves which entrain developing neurons to grow in a predictable fashion over a surface. These studies show that both electrospun and electrosprayed materials can be the foundation of materials with useful micro-topography and bioactivity.

To produce these microfluidic channels, a viscous solution of polymer is electrospun through a mon-axial nozzle. Were this process unmodified, the resultant fibers would be deposited as a randomly arranged, nonwoven mat. In this study, an alternating electrical field was applied to the process, which drew the charged fibers first one way, then the other, into alignment{1}. Electrostatic fields are readily manipulated, and have been successfully used to evenly distribute fibers, and even to cross-hatch them across multiple axes{1}.

A solution was then laid over the fibers, which retained an impression of them on its surface. Any solution that preserves the form of the fibers it is laid over as it dries or hardens is appropriate. This hardening process can readily be engineered to preserve the most delicate of bioactive macromolecules against the subtle temperature changes and shear stresses that are inescapable in electrospinning. Enzymes can also be densely immobilised on such surfaces. This way, replica-moulded surfaces may express an even broader repertoire of immobilised cell signals than the nanofibers which cast them. {2}.

This technique is interesting, and differs from tissue engineering, because its ultimate aim is not to mimic the natural conditions of a tissue, but to support the outgrowth of a small amount of living matter onto a highly artificial and linear environment. The authors of the replica moulding technique have since developed their technology by fitting it onto microchips{3}. With further advances, which are likely to be driven by precise, flexible electrohydrodynamic apparatus such as Spraybase, cells grown on artificial, replica-molded surfaces could be monitored by, interact with, and even guide machines in a more precise manner than what is currently possible, paving the way towards improved medical monitoring devices, advanced prosthetics, and enhancements to brain-computer interfaces.

  1. Electrospun Fiber Template for Replica Molding of Microtopographical Neural Growth Guidance. doi: 10.1002/smll.201101199
  2. Precise manipulation of cell behaviours on surfaces for construction of tissue/organs. doi: 10.1016/j.colsurfb.2014.08.026
  3. Neuronal Networks: Assembly of Functional Three-Dimensional Neuronal Networks on a Microchip. doi: 10.1002/smll.201470079