Previous efforts to utilize mammalian spinal cord neurons as biosensor elem
ents have relied on neuronal: glial cocultures maintained in serum-containi
ng media. We have examined the feasibility of culturing primary spinal cord
neurons in serum-free medium, modified for neuronal longevity, on fabricat
ed microelectrode arrays. Embryonic day 15 rat spinal cord cells were plate
d on trimethoxysilyl-propyldiethylenetriamine coated microelectrode arrays
comprised of gold recording sites passivated with silicon nitride. Immunocy
tochemistry was performed to verify the presence of neurons and quantitativ
ely assess astrocytes using antibodies against glial fibrillary acidic prot
ein on the silicon nitride substrates. Modifications to culture media enabl
ed viable neuronal culture to extend from approximately 14 days in vitro (D
IV) to 40 DIV on the arrays containing only 1.1 +/- 0.5% (mean +/- SEM) ast
rocytes. Extracellular recording revealed tetrodotoxin-sensitive spontaneou
s electrical activity from the enriched neuronal culture. Threshold detecti
on of extracellular potentials showed an increase in spike rate as a functi
on of glutamate concentration with neurotoxicity at elevated levels. This a
pproach suggests that functional measures related to biosensor applications
, pharmacological screening, or the evaluation of neurological disease mode
ls can be implemented in a defined culture system. (C) 1999 Elsevier Scienc
e Ireland Ltd. All rights reserved.