Self-assembly of conducting polymer nanomaterials for bionic applications

Instigating effective neural regeneration in the injured adult central nervous system (CNS: brain and spinal cord) following injury remains a distant and challenging goal. After CNS injury, the formation of cystic cavities results in substantial tissue defects and a growth inhibitory injury gap that restricts the potential for any nerve regeneration. This injury gap is not only biochemically inhibitory but also lacks the necessary cues and directional environment with which to replicate key processes observed during CNS development i.e. axon pathfinding as well as the formation of long linear axonal tracts at later stages of development. Recent work involving the incorporation of conducting polymers into tissue engineering biomaterial structures has demonstrated some promise in using electrical stimulation to control the behaviour of neurons and their processes. In addition to the scientific challenges presented here, a tissue engineering approach is hampered by classical fabrication problems of balancing efficacious and cost effective fabrication approaches with the need for the ease of fabrication and biomaterial sophistication. This can be overcome with unique self-assembly techniques. In the present study, biomaterials incorporating aligned arrays of conducting polymers were fabricated using the using self-assembly and capillary force lithography (CFL). Initial work investigated the generation of nanowires from a liquid matrix with a magnetic field culminated in the fabrication of conducting magnetic nanowires which could be assembled into nanowire arrays. CFL was then used to fabricate a platform consisting of aligned patterns of conducting multifunctional nanoparticles. This platform demonstrated no biocompatibility complications while its functionality was demonstrated by the electrical stimulation of cultured neurons. The results show that fabricating such materials using unconventional techniques is indeed feasible to produce novel biomaterials for implantation within the injured CNS. In doing so, it may prove possible to promote and guide regenerating axons through tissue defects, leading to better functional and morphological outcomes.