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Extracellular electrical recordings using poly (L-lactic) acid coated electrodes

Gomes, H.L.

Extracellular electrical recordings using poly (L-lactic) acid coated electrodes, Proc Conf. da Sociedade Portuguesa de Materiais - Materiais, Aveiro, Portugal, Vol. , pp. - , April, 2017.

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Abstract
Poly (L-lactic) acid (PLLA), a semi-crystalline synthetic polymer, is a promising material for bone tissue engineering due to its particular properties combination namely biodegradability, biocompatibility and piezoelectricity.
In this contribution gold microelectrode arrays coated with thin layer of PLLA fibres were used to record electrophysiological signals from autonomous cardiac contractile cells present in embryoid bodies (EBs) and from zebrafish hearts. The goal is to make use of the PLLA piezoelectric properties to detect ultra-small mechanical forces generated by the cell contractile activity.
Fig. 1 shows a set of periodic electrical current pulses recorded using a PLLA coated electrode. The spikes corresponds the beating frequency of a zebrafish heart placed on top of the PLLA based electrode. Periodic burst of small electrical oscillations were also detected using PLLA films. We propose these oscillations are caused by mechanical forces generated during the cardiac beating. These findings seem to confirm the piezoelectric behaviour of PLLA fibres.
The signals generated in the piezoelectric film were record by measuring the displacement current across the interfacial double-layer (Helmholtz layer) established at the PLLA/cell culture medium interface. This method is extremely sensitive and allows the detection of ultra-week electrical signals (few pico-amperes) with a signal-to-noise ratio that can reach values higher than 30.
PLLA coated electrodes were also evaluated as piezoelectric stimulators for zebrafish bone-derived cell lines. Preliminary results are reported.

Acknowledgments
This work received financial support from the Portuguese Foundation for Science and Technology (FCT), through the project the projects “Implantable organic devices for advanced therapies (INNOVATE PTDC/EEI-AUT/5442/2014 and trough the Institute of Telecommunications.