3D Fuzzy Graphene Microelectrode Array for Neurotransmitter Sensing at Sub-cellular Spatial Resolution

Dopamine (DA) is a monoamine neurotransmitter involved in the modulation of various physiological brain functions, including learning, motivation, reward, and motor functions. The development of a high sensitivity real-time sensor for multi-site detection of DA with high spatial resolution has critical implications for both neuroscience and clinical communities to improve understanding and treatments of neurological and neuropsychiatric disorders. Here, we present high-surface area out-of-plane grown three-dimensional (3D) fuzzy graphene (3DFG) microelectrode arrays (MEAs) for highly selective, sensitive, and stable DA electrochemical sensing. 3DFG microelectrodes present a remarkable sensitivity to DA (2.87 ± 0.25 nA/nM, with

LOD of 990±15 pM), the highest reported for nanocarbon MEAs using Fast Scan Cyclic Voltammetry (FSCV). The high surface area of 3DFG allows for miniaturization of electrode down to 2 x 2 μm^2, without compromising the electrochemical performance. Moreover, 3DFG MEAs are electrochemically stable under 7.2 million scans of continuous FSCV cycling, present exceptional selectivity over the most common interferents in vitro with minimum fouling by electrochemical byproducts, and can discriminate DA and serotonin (5-HT) in response to the injection of their 50:50 mixture. These results highlight the potential of 3DFG MEAs as a promising platform for FSCV based multi-site detection of DA with high sensitivity, selectivity, and spatial resolution.