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- Ultrasensitive gold micro-structured electrodes enabling the detection of extra-cellular long-lasting potentials in astrocytes populationsPublication . Mestre, Ana L. G.; Cerquido, Monica; INÁCIO, PEDRO; Asgarifar, Sanaz; Lourenco, Ana S.; Lurdes S. Cristiano, M.; Aguiar, Paulo; Medeiros, Maria C. R.; Araújo, Inês; Ventura, Joao; Gomes, Henrique L.Ultra-sensitive electrodes for extracellular recordings were fabricated and electrically characterized. A signal detection limit defined by a noise level of 0.3-0.4 mu V for a bandwidth of 12.5 Hz was achieved. To obtain this high sensitivity, large area (4 mm(2)) electrodes were used. The electrode surface is also micro-structured with an array of gold mushroom-like shapes to further enhance the active area. In comparison with a flat gold surface, the micro-structured surface increases the capacitance of the electrode/electrolyte interface by 54%. The electrode low impedance and low noise enable the detection of weak and low frequency quasi-periodic signals produced by astrocytes populations that thus far had remained inaccessible using conventional extracellular electrodes. Signals with 5 mu V in amplitude and lasting for 5-10 s were measured, with a peak-to-peak signal-to-noise ratio of 16. The electrodes and the methodology developed here can be used as an ultrasensitive electrophysiological tool to reveal the synchronization dynamics of ultra-slow ionic signalling between non-electrogenic cells.
- Extracellular electrophysiological based sensor to monitor cancer cells cooperative migration and cell-cell connectionsPublication . Asgarifar, Sanaz; Mestre, Ana L. G.; Félix, Rute; Inacio, Pedro M. C.; Lurdes S. Cristiano, M.; Medeiros, Maria C. R.; Araújo, Inês; Power, Deborah; Gomes, Henrique L.Herein, we describe an electrophysiological based sensor that reproducibly monitors and quantifies in real-time collective migration and the formation of cell-cell junctions by C6 glioma cells seeded on top of electrodes. The signal amplitude and frequency generated by the migrating cells changed over time and these parameters were used to accurately calculate the migration speed. Electrophysiological measurements could also distinguish individual from collective cell migration. The migration of densely packed cells generated strong signals, while dispersed cells showed weak bioelectrical activity. We propose this electrophysiological technique as a cell-based biosensor to gain insight into the mechanisms of cooperative migration of cancer cells. Possible applications include screening for anti-migratory compounds, which may lead to the development of novel strategies for antineoplastic chemotherapy.