Selective neuron growth on ion implanted and plasma deposited surfaces

Summary form only given. To learn about how large systems of neurons communicate, we need to develop, among other things, methods for growing patterned networks of large numbers of neurons. Success with this challenge will be important to our understanding of how the brain works as well as to novel kinds of computer architecture. Large in vitro networks could show, for example, the emergence of stable patterns of activity and could lead to an understanding of how groups of neurons learn after repeated stimulation. We have investigated the use of ion implantation and plasma deposition on the substrate on which neurons will subsequently be grown, using ion species that enhance or inhibit neuron cell attachment, as a means for forming regions of selective neurocompatibility. Lithographic masks, for example, can then be used to form desired patterns. Plasma deposition of optically transparent, electrically conducting, ultra-thin metal films can also be used to form electrodes for extra-cellular electrical stimulation of neurons. Ion implantation was carried out using a vacuum arc ion source (Mevva) to provide energetic (/spl sim/100 keV) broad beams of metal ions, and plasma deposition was done using a filtered vacuum arc system. Substrates were glass microscope slides; some of the experiments utilized simple lithographic masks to form patterns of ion beam or plasma deposition treated regions. PC-12 rat neurons were then cultured on the treated substrates and the growth monitored. Particularly good results were obtained, for example, for the cases of ion implantation with tantalum and of plasma deposition of carbon to form a diamond-like carbon film of thickness several hundred Angstroms. Neuron growth showed excellent contrast, with prolific growth on the treated regions and very low growth on the untreated regions. Here we describe our work along these lines and summarize the results to-date.