Development of the Neuron-Electrode Interfaced Network Using Dynamic Substrate Based on Alginate Hydrogel

Abstract

Event Abstract Back to Event Development of the Neuron-Electrode Interfaced Network Using Dynamic Substrate Based on Alginate Hydrogel Sunghoon Joo1, Seukyoung Song2, Yoon S. Nam2 and Yoonkey Nam1* 1 Korea Advanced Institute of Science and Technology, Department of Bio and Brain Engineering, Korea 2 Korea Advanced Institute of Science and Technology, Department of Materials Science and Engineering, Korea Motivation To study the signal processing such as learning and memory between neurons in network scale, In vitro neural network have been used as a powerful and controllable model system. However, the neural network without any control of cell-positioning and axon-guidance is too complicate to figure out the structure of the network. To reduce the limitation of randomly positioned neural network, neuron patterning techniques based on microfabrication, material engineering, and chemical engineering have recently been developed and applied on the MEA substrate [1]. In this study, we selectively control the cell adhesiveness of MEA surface using alginate hydrogel. Using this method, we can design the neural network where neurons are positioned precisely on the electrodes of MEA and the clusters of neurons are freely connected. Material and Methods Polydimethoxysiloxane (PDMS) molds were manufactured by soft-lithography. The mold was placed on the poly-D-lysine coated MEA (MultiChannel Systems, Germany), and 0.1% (w/v) alginate solution was applied to the mold. Calcium ion source, 1% CaCl2, was treated for gelation of alginate solution by ionic cross-linking. After the removal of PDMS mold, neuronal cells were seeded onto the pattern. The alginate hydrogel background could be dissolved by the addition of 10 mM Na2CO3 to remove calcium ion which cross-linked alginate hydrogel at 4 DIV. Results Figure 1a shows that the connection of the neuronal network after removal of the alginate hydrogel from the MEA. Before the removal of the alginate, neurons on each electrode were separated due to the cell repulsive nature of alginate hydrogel. The alginate hydrogel background was dissolved by the treatment of 10 mM Na2CO3 at 4 DIV. After a few days, the cell body of neurons were located only on the electrodes, but the neurons were connected by neurites. From the networks, electrical signals were successfully measured by neural signal amplifier (Gain: 1100, bandwidth: 10 Hz ~ 5 kHz, MultiChannel Systems) at 15 DIV (11 days after the removal of alginate) as provided in Figure 1b. Discussion Our designing method to make neuron-electrode interfaced network has many advantages. A biocompatible material, alginate hydrogel, was used to control the cell adhesiveness on MEA substrate. The alginate background can be easily removed by the treatment of Na2CO3 solution. Because of neuron-electrode interfacing of our neuronal network, the measurement of electrical activity could be enhanced compared to the randomly positioned neural network. Conclusion In this work, we suggest a simple, but effective method to pattern the primary neural network where neurons were patterned on electrodes and each cluster of neurons were freely connected using dynamic substrate based on alginate hydrogel. Using the MEA system, we recorded the electrical activity from the patterned neuronal network.