Formation of Bio-interface by Patterned Negative Ion Implantation Treatment

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(1)Formation of nerve cell network by negative ion implantation :We implanted carbon negative ions into various polymer materials of polystyrene PS, silicone rubber SR and polyimide PI, which were spin-coated on glass, through a pattern mask with 87 slits (aperture width of 50μm). Attachment properties of Nerve cells PC-12h (rat adrenal pheochromocytoma nerve cell) were investigated on the various C-implanted polymers. Under conditions of ion energy more then 10 keV and dose more than 3x10^<15> ions/cm^2, the cells showed selective attachment on ion-implanted region for polystyrene and silicone rubber. On the other hand, they did not show it on the polyimide. Under the low energy condition of 5 keV, however, nerve cells showed the selective attachment on implanted area of polyimide. Neurite from the cell body also showed selective extension over the implanted area for PS,SR, and PI as well as cell attachment properties.(2)Surface controls of wettability and protein adsorption on polyme … More rs by negative ion implantation :We applied to measure the contract angle of water on ion-implanted various polymers by bubble method in water as well as water-drop method in air. We found that the implanted surface required many hours in water and culture medium to stabilize it surface state. Therefore, the bubble method is suitable way for evaluation of cell attachment properties. Decrease of contact angle on the surface, i.e., becoming hydrophilic was obtained were by carbon negative ion implantation : about 10° for polystyrene and 20° for silicone rubber. On the other hand, the polyimide showed an increase of contact angle, i.e., hydrophobic, about 15° by implantation. Protein adsorption was also tested for nerve growth factor NGF,FGF, and gelatin after dipping in protein-PBS solution. Nitrogen amount (from the protein) on C-implanted PS and SR surface was detected much more than that on un-implanted area by XPS analysis. This means C-implanted PS and SR were able to adsorb protein and then result selective attachment of nerve cells and neurite.(3)Response of cells selectively attached on C-implanted area of PS against externally applied electric impulse from conductive coupling electrode pad below the PS film :We investigate the outgrow of neurite from attached cells by externally applied electric impulse from conductive coupling pad. We obtained preferential outgrow of neurite from cells toward positive electric pulse electrode rather than the other electrode. This means the possibility of artificially control of connecting pattern among cells with axons. By using patch clump method, excitation of nerve cells was confirmed to be induced by the externally applied electric impulse with inductive coupling. As a result, the bio-interface between bio-nerve system and external semiconductor circuit was able to be formed by using our developed negative ion implantation method. Less