Flexible optoelectronic biointerfaces with pseudocapacitive MnO2 nanostructures for efficient photostimulation of neurons

This thesis explores the integration of flexible optoelectronic biointerfaces with 3D manganese dioxide (MnO2) nanoflowers to achieve safe and efficient photostimulation of neurons. Optoelectronic biointerfaces have attracted significant attention for their potential in the wireless and electrical control of neurons. By utilizing 3D pseudocapacitive nanomaterials with interconnected porous structures and large surface areas, these biointerfaces can effectively transduce light into ionic currents, meeting the requirement for high electrode-electrolyte capacitance. The MnO2 nanoflowers were grown through a chemical bath deposition technique on the return electrode, which was pre-coated with a MnO2 seed layer deposited via cyclic voltammetry. The nanoflower integrated biointerfaces exhibited excellent performance with a high interfacial capacitance (greater than 10 mF cm-2) and photogenerated charge density (over 20 μC cm-2) even under low light intensity conditions (1 mW mm-2). Importantly, the MnO2 nanoflowers induced safe capacitive currents through reversible Faradaic reactions and demonstrated no toxic effects on hippocampal neurons during in vitro experiments, making them a promising material for curvature fit integration with electrogenic cells. The functionality of the optoelectronic biointerfaces was assessed using a patch-clamp electrophysiology setup in the whole-cell configuration of hippocampal neurons, revealing their ability to elicit repetitive and rapid firing of action potentials in response to light pulse trains. This research underscores the potential of electrochemically-deposited 3D pseudocapacitive nanomaterials as a robust and efficient approach for controlling neurons through optoelectronic means.