3:30 PM - SB08.05.07
Patterned Semiconducting Multi-Electrode Arrays for the Optical Stimulation of Neuronal Cells
Frano Milos1,Maria Rosa Antognazza2,Gabriele Tullii2,Maria Cecilia Pasini3,Francesco Galeotti3,Dirk Mayer1,Andreas Offenhäusser1
Forschungszentrum Juelich1,Istituto Italiano di Tecnologia2,ISMAC-CNR3
Photoconductive organic polymers are attracting considerable interest in tissue engineering and bioelectronics due to their remarkable light absorption along with tunable optical and mechanical properties.[1,2] Moreover, these materials can be easily processed into precisely defined topographical patterns with large area coverage and low fabrication costs. We present a novel photoconductive biointerface which combines a multi-electrode array (MEA) functionalized with a semiconductive conjugated polymer patterned into defined microscale topographical features. In previous studies, photoexcitation of a light-sensitive semiconductive polymer, poly(3-hexylthiophene-2,5-diyl) (P3HT), was used to induce variations in the membrane potential of HEK-293 cells  and the occurrence of capacitive charging was observed at the P3HT/electrolyte interface that could potentially lead to photo-capacitive stimulation of the cell membrane. Our aim is to further this approach by developing a functional non-invasive tool for the optical and topographical modulation of primary cortical neurons in vitro.
Poly(3-hexylthiophene-2,5-diyl) was deposited on MEAs and patterned into conical micropillars to improve the cell-electrode coupling. Since P3HT is excited by visible light, the presented device can be easily implemented in any electrophysiological set-up without requiring complex optical systems. We observed that polymer photoexcitation leads to a significant decrease in the electrode impedance. Furthermore, we cultured primary cortical neurons and observed that microscale pillars significantly promote neurite growth and their alignment to the underlying topography in comparison to flat substrates commonly used in cell culture. Since light treatment did not result in significant detrimental effects on cell viability, we aim to optically stimulate primary cortical neurons using the presented device and further investigate whether polymer photoexcitation influences neuronal development on flat and patterned P3HT substrates.
In conclusion, the presented system is a step towards light-controlled manipulation of neuronal development and network activity which could have considerable implications for neural regeneration and the design of neuro-prosthetic devices.
 N. Martino, D. Ghezzi, V. Benfenati, G. Lanzani, M. R. Antognazza, J. Mater. Chem. B 2013, DOI 10.1039/c3tb20213e.
 V. Benfenati, S. Toffanin, S. Bonetti, G. Turatti, A. Pistone, M. Chiappalone, A. Sagnella, A. Stefani, G. Generali, G. Ruani, et al., Nat. Mater. 2013, 12, 1.
 N. Martino, P. Feyen, M. Porro, C. Bossio, E. Zucchetti, D. Ghezzi, F. Benfenati, G. Lanzani, M. R. Antognazza, Sci. Rep. 2015, 5, 1.
 G. Tullii, A. Desii, C. Bossio, S. Bellani, M. Colombo, N. Martino, M. R. Antognazza, G. Lanzani, Org. Electron. 2017, 46, 88.