Guided Axon Outgrowth of Neurons by Real-Time Femtosecond Laser Penetration on a 4 μm Thick Thin-Glass Sheet

Transplantation of scaffold-embedded guided neurons has been reported to increase neuronal regeneration following brain injury. However, precise axonal integration between host and transplant neurons to form functional synapses remains a major problem. This study aims to develop a real-time femtosecond (fs) laser penetration on a 4 m thick thin-glass sheet to promote guided axon outgrowth influenced by molecular gradients in a microfluidic device. The device enables the introduction of the guidance molecule (i.e., netrin-1), neuronal culture, and manipulation by fs laser. After fabricating multiple micro-holes on the thin-glass sheet using fs laser, netrin-1 gradients with radial concentrations are generated in the chamber, affecting axon outgrowth and guidance. A majority of axons (~92%) experiences guided outgrowth with positive angular changes towards netrin-1 gradients. These results demonstrate the capability of the precise and real-time manipulation system based on a fs laser and a microfluidic device to control the growth of neurons.