Preparing Novel Nanoscale Photoelectrode For Neural Modulation Of Brain

Electrical stimulation is one of the most common neuromodulation techniques in the treatment of nervous system diseases.Electrode is an essential part in the implementation of nerve electrical stimulation therapy,which can replace the damaged neurons to accomplish the transmission of signals between neurons.So,it is necessary to implant electrodes for long-term electrical stimulation in neural diseases treatment.However,the traditional electrodes are relatively large,which will inevitably cause immune response in tissue around the electrodes,and also the gradually make the loss of the electrode performance with the extension of the implantation time.Although the injectable mesh electrode has solved the problems of implantable electrodes,it is still in need of further research due to its low bending stiffness,which would cause deflection during the injection process,and high requirements for equipment.As a new type of neural electrode,nano-photoelectrode,which can be injected in situ into a specific brain region,can controllably stimulate the nerve activity by the applied light irradiation,which high flexibility and spatiotemporal resolution.Here,the photoresponsive semiconductor nanomaterials have been designed and synthesized to regulate neurons,with the main researches as follows:1.Novel nanoscale capacitive photoelectrode for nerve modulation.The photoelectrode was constructed by zinc porphyrin(Zn TPyP)self-assembled nanorods(ZSND@TO)with TiO₂coating outside,which can optically boost the ionic current across ZSND@TiO₂/membrane interface for neuromodulation via a capacitive process.J-aggregated Zn TPyP array facilitates the long-distance exciton diffusion to the heterojunction interface in ZSND,and ultrafast electron injection into TiO₂,forming TiO₂(e^-)due to the dynamic electron injection characteristics of TiO₂.The formed TiO₂(e^-)can drive the external membrane cation reversible adsorption on its surface,to inducing the depolarization of threshold potential of neurons and the generation of action potential,with high spatiotemporal specificity.In vivo BOLD f MRI and c-Fos mapping show that ZSND@TO in mice brain triggers the local neuronal clusters activation upon light irradiation,as well as the stimulatory effects on downstream regions,without significant immune inflammatory reaction and free radical damage.This photoelectrode provides an alternative to optogenetics,which may be developed as injectable prostheses for the treatment of neurological disorders as well as trauma restoration.2.Novel nanoscale pseudocapacitive photoelectrode for the modulation of neuronal activity.The nanocomposite of Zn TPyP and Au was first fabricated(ZSA)and then coated with MnO₂ nanosheets(ZSAM).Au in ZSA will promote the formed excitons upon light irradiation to separate and diffuse to the surface of MnO₂.MnO₂ as a classical pseudocapacitor electrode material,will interact with electrons and Na⁺on its surface to produce reversible redox reaction and then make the change of charge distribution around.When ZSAM was attached to neuron outside,the reversible redox reaction at ZSAM/neuron membrane interface will be induced by light stimulation to form pseudo capacitive current,and so to induce neuron depolarization and produce action potential.Calcium imaging data of nerve cells in vitro showed that 405 nm laser stimulation triggered Ca²⁺influx,meaning nerve cells depolarization,without the generation of harmful substances such as reactive oxygen species during the whole process of light stimulation.In fact,the formation of a pseudocapacitive current could give a high charge injection density under low light power irradiation,which may provide a significant reference for further research of new neural electrode.