Axonal guidance by surface microstructuring for intracellular transport investigations.

Intracellular transport, a complex interplay of diverse processes, is fundamental for the development, function and survival of cells. Passive diffusion and active transport phases alternate in living cells, with active phases arising from molecular motors, such as kinesin or dynein, pulling cargoes along microtubules. A better understanding of stochasic mechanisms involved in motor-microtubule interactions and in diffusion processes, which enable efficient active transport over long distances in motor neurons, requires a better link between theoretical models and live-cell experiments. Herein, we establish one-dimensional (1D) intracellular transport geometries, suitable for comparing experimental findings with recent theoretical 1D model predictions, by guiding axonal outgrowth of pheochromocytoma (PC12) cells along predefined chemical surface structures with a strip width of 2 microm, fabricated by means of microscale plasma-initiated patterning (microPIP method). Quantification of the intracellular transport of quantum dots (QDs) in straight axons, which exhibit almost parallel microtubules, is obtained by our recently developed algorithm based on a time-resolved mean-square displacement (MSD) analysis. Such a thorough dissection of experimental data will be useful for validation and clarification of current theoretical transport models.