Brain neuronal cells, in general, require some cation sites of surface such as poly-lysine and poly-ethylene-imine for the cell immobilization on the solid surface. Therefore, we have developed a degradation method of adhesive proteins by using negative-ion implantation for neuron adhesion patterning in order to make artificial nerve network with a simple structure. In our previous study, the direct surface modification by carbon negative-ion implantation into polymers was effective for pattern adhesion of neural-like cell, endothelial cell, and stem cells. But it is not effective for the brain nerve cells. We have tried to modify the coated proteins such as poly-lysine for neuron pattering.

Polystyrene (PS) were firstly dip-coated with the one of amine acid of poly-D-lysine (PDL) in the concentration of 0.5 – 1,000 µg/ml for 1 – 2 h at 37^oC and were dried for 30 min. Then, carbon negative ions were implanted into the samples at 10 keV and doses of 10¹⁴ – 10¹⁶ ions/cm² through a micro-pattern mask, which consists of many slit apertures with 50-µm width and 70-µm spacing. XPS analysis showed the changes of atomic bonding state after ion implantation. With an increase in the ion dose, amount of nitrogen atoms in the proteins decreased while those of oxygen and carbon increased. After culturing of rat embryonic brain cortex neuronal cells (EBCN) on the implanted PS, the EBCN cells adhered on only unimplanted surface of PLD-coated PS at ion fluence of 10¹⁴ ions/cm², respectively. Thus, we have successfully obtained pattern adhesion of natural living nerve cells.