(252e) Tuning Surface Properties of Acrylate Polymers to Direct Neurite Growth

A potential strategy to overcome spatial resolution barriers in neural prosthetic devices, such as a cochlear implant (CI), is to direct the regrowth of axons toward the stimulating electrodes. Both physical and biochemical cues have been shown to orient neurite outgrowth. In this work, micropatterns, both physical and biochemical, on acrylate polymers are used to direct the growth of primary spiral ganglion neurons (SGNs), the primary neural receptors of CIs. Utilizing the inherent spatial and temporal control of photopolymerization, physical microgrooves are fabricated using a photomask. Spatial control of the photopolymerization allows ridges to form under transparent bands and grooves under opaque sections forming a microgrooved polymer that can direct SGN neurite outgrowth. Biochemical patterns are fabricated by adsorbing laminin, a cell adhesion protein, onto polymer surfaces followed by select photobleaching of exposed protein using a similar photomask forming parallel bands of adhesion protein to promote directed elongation. SGN neurite alignment was evaluated for physical and biochemical patterns independently, both showing excellent elongation along parallel micropatterns when compared to unpatterned controls. Additionally, competing biochemical and physical cues were evaluated by first fabricating physical microgrooves followed by forming perpendicular biochemical patterns by rotating the photomask ninety degrees. The physical cues were varied by independently changing both the amplitude and the band spacing of the microgrooves, with higher amplitudes and shorter band spacing showing increased alignment. As the intensity of the physical cue in competing systems decreased SGN neurites showed increased alignment along laminin patterns. These findings provide insight into neurite pathfinding and improving the neural prosthetic/biomaterial interface.