Miniature Transparent Dopamine Sensor Based on Nanosphere Lithography

Detection of neurotransmitters for in vitro analysis systems is an essential component in evaluating the integrity and viability of in vitro models of neurodegenerative disorders and the cytotoxicity of drug candidates. Currently, electrochemical analysis such as cyclic voltammetry (CV) is the most widely used method for the detection of neurotransmitters. However, while most in vitro analysis systems are based on optical imaging, electrochemical sensors are non-transparent and hinder in situ simultaneous cell monitoring. In this work, a highly sensitive miniaturized electrochemical sensor that is also transparent is proposed, which enables simultaneous dopamine detection and in vitro optical assays. The microfabrication process and nanosphere lithography are utilized to fabricate a transparent working electrode. The transparent electrode is functionalized with the overoxidized polypyrrole/sodium dodecyl sulfate-modified carbon nanotube (OPPy/SDS-CNT). The detection of DA is successfully demonstrated using the miniaturized transparent sensor. In addition, the PC-12 cell is cultured in the sensor-integrated chamber and the cell viability is confirmed on the sensor over 3 days. The proposed miniature transparent sensor is a great candidate for next-generational multi-modal in vitro analysis systems.