Nanomaterial-Enabled Optical Modulation of Cellular Activity

 High precise control of neural activity is essential for understanding the communication between cells and developing interventions for neurological disease. Light-responsive nanomaterials pave an avenue for remote and non-genetic neural modulation with high spatiotemporal resolution and specificity. The nanomaterials interfaced with neurons enable the energy transfer from incident light energy to local electrical field and/or heat release, therefore affecting the neurons’ membrane electrical properties and the ion channels. Here, we engineered the nanostructures and chemistry of Si, C, and MXene, to achieve the optical control of neurons with sub-µJ incident light energy. We tailored the structure of chemical vapor deposition (CVD) synthesized Si and graphene heterogeneous junction to tune the photocapacitive and photothermal responses by controlling the thickness, Si crystallization, graphene edge density, and doping type. We also demonstrated that Ti3C2Tx (MXene) is an outstanding candidate for exciting neurons due to its high near-infrared absorption, high photothermal conversion efficiency, biocompatibility, and low requirement in incident energy for eliciting the action potentials. We further systematically investigate the cytotoxicity and phototoxicity of the photothermal modulation using Ti3C2Tx across multiple assays, including cellular viability, cellular stress, and oxidative stress, and benchmark the safe range of laser illumination conditions to avoid irreversible damage to the cells. The efforts in expanding the application and material library of photothermal modulation in multi-dimensionality will benefit the further perspective of using light for decoding the cellular communication mechanisms and exploring the treatment for neurological diseases and tissue regeneration.