KCS

Neuronal cells have cellular gap junctions called ‘synapses’ between two adjacent neurons where the transmission of electrochemical information takes place. Research on various events occurring at the synaptic cleft, however, has been limited owing to the poor spatial accessibility to extremely narrow gap, ~20 nm wide. To approach the electrochemical events at the synapse in another direction, we made attempts to induce synapses directly on the artificial surface including electrodes instead of conventional neuroelectrochemical system, e.g. inserting a sharp nano-electrode into a synaptic cleft. To that end, we engineered neuroligin 1 (NL1), a synaptic cell adhesion molecule (CAM), which is known to drive the formation of presynapses. NL1 was biotinylated following an in vivo process to be immobilized on streptavidin-coated surface. Such engineered proteins on microbead substrates brought about the glutamatergic (excitatory) pre-synaptic differentiations when co-cultured with primary hippocampal neurons. In addition to excitatory synaptic CAM, we were able to prepare inhibitory one, Slitrk3, on the same kind of microbeads. Microfluidic chip allows us to make synaptic CAM modified beads exposed to pure axons from the embryonic hippocampus neurons seeded on PDK coated glass surface. We confirmed the engineered post-synaptic CAMs are capable of inducing artificial synapse through which persistent and durable information transmission takes place between live neurons and electronic devices. With this new system, we would be able to do real electrochemistry at artificial synapse and see what happens inside the synapse-electrode interface, suggesting an innovative breakthrough in neuroelectrochemistry.