Browsing by Author "Inacio, Pedro M. C."
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- 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.
- Ultra-low noise PEDOT:PSS electrodes on bacterial cellulose: A sensor to access bioelectrical signals in non-electrogenic cellsPublication . Inacio, Pedro M. C.; Medeiros, Maria C. R.; Carvalho, Tiago; Félix, Rute; Mestre, Ana; Hubbard, Peter; Ferreira, Quirina; Morgado, Jorge; Charas, Ana; Freire, Carmen S. R.; Biscarini, Fabio; Power, Deborah; Gomes, Henrique L.This study is focused on the particular advantages of organic-based devices to measure cells that do not generate action potentials, also known as non-electrogenic cells. While there is a vast literature about the application of organic conductors to measure neurons, cardiomyocytes and brain tissues, electrical measurements of non-electrogenic cells are rare. This is because non-electrogenic cells generate weak signals with frequencies below 1 Hz. Designing low noise devices in a millihertz frequency range is extremely challenging due to the intrinsic thermal and 1/f type noise generated by the sensing electrode. Here, we demonstrate that the coating of cellulose nanofibers with conducting PEDOT:PSS ink allows the fabrication of a nanostructured surface that establishes a low electrical double-layer resistance with liquid solutions. The low interfacial resistance combined with the large effective sensing area of PEDOT:PSS electrodes minimizes the thermal noise and lowers the amplitude detection limit of the sensor. The electrode noise decreases with frequency from 548 nV r.m.s at 0.1 Hz to a minimum of 6 nV r.m.s for frequencies higher than 100 Hz. This low noise makes it possible to measure low frequency bioelectrical communication signals, typical of non-electrogenic cells, that have until now been difficult to explore using metallic-based microelectrode arrays. The performance of the PEDOT:PSS-based electrodes is demonstrated by recording signals generated by populations of glioma cells with a signal-to-noise ratio as high as 140.