In Vitro Assays of Neurite Outgrowth and Synapse Formation Using Thermoplasmonic Ablation Technique

A variety of in vitro assays have been designed based on optical imaging to study essential processes for nervous system development, such as neurogenesis and synaptogenesis. However, it is still difficult to assess the developmental processes under culture conditions where uncontrolled neurite growths and numerous neuronal connections occur all at the same time. Moreover, present techniques for in vitro assays lack the ability to induce and evaluate these processes at a specific time point. In this study, we applied a nanoparticle-assisted thermoplasmonic ablation of a cell-repulsive hydrogel to realize assays for two developmental processes: neurite outgrowth and synapse formation. We successfully demonstrated that this technique could guide neurites or make connections at different cultivation times, and the length of growing neurites and the number of forming synapses could be quantified. Our developed method for in vitro assays is expected to be helpful in studying various neurodevelopment processes occurring at different developmental stages.