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Understanding the changes in the electrochemical properties of neural cells upon exposure to stress factors imparts vital information about the conditions prior to their death. This study presents a graphene-based biosensor for real-time monitoring of N27 rat dopaminergic neural cells which characterizes cell adhesion and cytotoxicity factors through impedance spectroscopy. The aim was to monitor the growth of the entire cell network via a nonmetallic flexible electrode array. Therefore, a water-based graphene solution was formulized as a conductive ink, 3D-printed into a flexible substrate through an electrohydrodynamic approach, resulting in electrodes with a conductivity of 6750 s/m. The presented high-throughput method enabled microscale monitoring of the entire cell network via the design of PDMS-based growth channels. The electrical resistance of the cell network was measured continuously along with their network density, constituting a mean density of 1890 cell/mm2 at full cell confluency. The results demonstrate the applicability of the impedance-based sensing of the cell network for rapid screening of the cytotoxic elements, and the real-time effect of UV exposure on dopaminergic neural cells was reported as an immediate application of the device.

Dopamine is critical for physiological function and plays a crucial role in the discovery of neurological disorders such as Parkinson's disease. Improving the measurement of this neurotransmitter could improve treatment, diagnosis, and prognosis of neurological disorders. Graphene's outstanding biocompatibility and electrical conductivity have caused it to become a widely used material in cellular interfacing and neurotransmitter characterization. However, graphene has been rarely used to investigate cellular systems after introducing trauma. Sensing dopamine on the cellular level and on the microscale can lead to providing a point of care diagnostics for traumatic brain injury patients. The sensitivity of graphene biosensor to different concentrations of dopamine was evaluated in the dynamic range of 0.1 - 100 μM and the limit of detection of biosensor was estimated to be 180 nM. In this work, a 3D printed graphene biosensor was used to characterize dopamine levels as a real-time detector of neurotransmitters. We used cyclic voltammetry (CV) to measure the response of graphene biosensors to neurotransmitter changes, in addition, to evaluate the effect of UV irradiation as the injury stimulant on the electrical properties of graphene biosensors. We demonstrated that the 3D printed graphene could detect significant changes in the CV profiles of N27 dopaminergic neural cells cultured on the graphene device in the face of trauma.