| Summary: | 碩士 === 國立成功大學 === 醫學工程研究所碩博士班 === 96 === Substrate with integrated microelectrode arrays (MEAs) provides an alternative electrophysiological method for recording the electrical activity from excitable cells. With MEAs, one can measure the electrical impedance of neuron electrode interface and elicit electrical stimulation from multiple sites of MEAs to determine the electrophysiological conditions of cells. The aims of this research were to construct an impedance and action potential measurement system for cultured neurons on MEAs to observe the electrophysiological signal transmission in neuronal network during glucose and oxygen deprivation (OGD) condition. An extracellular constant current stimulator producing the biphasic current pulse for neuron stimulation was first built in this study. The impedance monitoring during in vitro cell culture showed that a clear relationship to cell adhesion, cell growth and electrode impedance. The impedance of bared gold was measured at a stable value about 151 kΩ. After the PC12 cells were seeded on the substrate, the impedance dramatically elevated to the 286 kΩ and gradually increased to 503 kΩ during 4 days of culture resulting from the cell growth on the electrodes. Similar properties can be observed on the time-course growth of cortical neurons. After seeding of cortical neurons on the substrate, the impedance was dramatically increased to the 265 kΩ. Then, the impedance of cortical neurons was increased day by day due to the cell growth on the electrodes. From the time-course recording of impedance, OGD condition effectively induced neuronal damage in vitro. The impedance of PC12 and cortical neurons was monitoring during 5 days of in vitro culture was 465.0 kΩ and 516.2 kΩ, respectively. The impedance of both PC12 and cortical neuron decreased rapidly during OGD condition and fell into the level close to that bare gold electrode around 15 min. For extracellular stimulation study, the spontaneous activity was successful recorded in the cultured neurons. The cortical neuronal activity was recorded and the suitable stimulation window was determined. However, the stimulation results were affected by electrode impedance as well as by the sealing impedance resulting from neuron cells covering the electrode. Further development is to utilize surface modification on the electrode for better adhesion of cultured neuron to the electrodes. By using the powerful tools, it can be used as drug screening purpose to monitoring the electrophysiological properties of cultured neuronal networks.
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