Electrically Contrasting Periodic Polymer Interfaces Guide Neuronal Networks

The nervous system constitutes a highly ordered, integrated network of cells. Understanding this neuroanatomical architecture in vitro is fundamental to elucidating the cellular computations underlying functional network formation. Neuronal connectivity orchestrated through axonal pathfinding, is an interplay of biochemical signals and electromechanical properties of the growth substrate. This study focusses on how neuronal morphology and networking are affected by the periodic, micrometer-scale patterned stripes of two electrically contrasting polymers - poly(vinylidenefluoride-trifluoroethylene) (PVDF-TrFE) and poly(3,4-ethylenedioxythiophene) - poly(styrene sulfonate) (PEDOT:PSS). This periodic confinement provides a length-scale driven cue which unfolds as a self-organized, frequency-modulated spatial phenomenon. Primary cortical cultures on these patterned substrates reveal significant differences with more elaborate network formation on PVDF-TrFE stripe. The features observed at the stripe boundaries, along with the dependence on stripe width, suggest that the neurons exhibit a preference to remain confined within the PVDF-TrFE region, with growth cones deflecting away from the PEDOT:PSS regions. These observations show a promising route for development of a functional template capable of directing axonal growth, synapse formation and neural rewiring in early models of connectivity disorders in vivo.