Spatiotemporally controlled navigation of neurite outgrowth in sequential steps on the dynamically photo-patternable surface.

A great number of the neurites interconnect neuronal cells in a brain to form the complicate neural circuits, whose structures are dynamically changed with changing the numbers and destinations of the neurites. Fabricating a model of neural network in vitro is one of the promising methods to precisely assay the signal transmission and processing within the circuit as well as to examine behaviors of individual cells. In this study, aiming to fabricate the dynamically alterable neural network in vitro, the chemically modified surface with the photo-reactive self-assembled monolayer was applied to navigate the neurite outgrowth activities of differentiated PC12 cell in the spatially and temporally controlled manner. Numbers of the cell soma were effectively adhered and simultaneously arrayed according to the 25 μm square patterns, which were easily fabricated with a single shot of the 365-nm ultraviolet (UV) irradiation and pre-coated with the extracellular matrix (ECM) protein. Narrow neurites were successively guided along the 5 μm line patterns drawn on the surface by stepwise irradiation of the UV light in the intended designs and at appropriate timing. Sprouting number, elongating direction, bending, branching, and formation of autapse-like structure were controllable. The rate of neurite elongation was dependent on the ECM species, that were pre-coated beneath the cell soma, suggesting the ECM stimulated the basal side of the cell soma and affected the outgrowth process of the neurite. Navigation of the neurite elongation along the microline pattern for a primary rat brain cortex neuron was also achieved.