Organic Electrochemical Transistor Arrays for Ultrasensitive Real-Time Mapping of Evoked Neurotransmitter Release in Living Animals
Student thesis: Doctoral Thesis
Related Research Unit(s)
Though neurotransmitters (NTs) play essential roles in neural signal transmission, techniques for fast in vivo analysis of electrochemical activity are still limited. Here, we describe an organic electrochemical transistor (OECT) array technique for monitoring the release of catecholamine neurotransmitters (CA-NTs) in brains of the living animals. The OECT-device comprises of a thin layer of organic semiconductive poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) as a transducer and a platinum (Pt) electrode for detecting the target chemicals, which is an active sensor with intrinsic amplification capability and fully compatible with modern microfabrication processes. Such transistor-based design enables real-time and direct readout of transient CA-NT release with a detection limit in the nanomolar range and a temporal resolution of 50 milliseconds. The device operates on low working voltage (~300 mV), and is permissive for continuous in vivo monitoring for hours without any significant signal drift or device deterioration, which is inaccessible for existing methods. We demonstrate successful quantitative detection of evoked dopamine release in different physiological scenarios in living animals. Further, the design of the micropatterned array of the OECT devices enables spatial mapping of dopamine release simultaneously at large multiple brain regions. Using the dopaminergic pathways as a working model, the OECT-array-facilitated mapping of dopamine release in the striatal brain reveals a complex cross-talk between the mesolimbic and the nigrostriatal pathways, which is heterogeneously affected by the reciprocal innervation between ventral tegmental area (VTA) and substantia nigra pars compacta (SNc).