Sensitivity of the neuronal network biosensor to environmental threats

It is widely acknowledged that there is a critical need for broad-spectrum environmental threat detection. While cells/tissue-based biosensors have been discussed for many years as a means of meeting this critical need, these kinds of systems have met with logistic concerns, in particular with regard to stability. Our group has been working with cultured neuronal networks, which have the capacity to respond to a wide range of neuroactive compounds and are sufficiently robust to be shipped to end users. The basis of operation involves extracellular recording using thin-film microelectrode arrays where spontaneous bioelectrical activity, that is, spike firing, can be monitored in a noninvasive manner conducive for potentially long-term measurements. This work describes the current status of our efforts for the fabrication of a portable biosensor that incorporates cultured neuronal networks grown over standardized microelectrode arrays. Based on our protocol for aqueous phase sample introduction under constant flow conditions, minimal variation in mean spike rate is observed, consistent with temporal stability, such that changes of > 10% are readily distinguished. To demonstrate the capability of this system, changes are reported in mean spike rate and network synchronization resulting from exposure to different model environmental threats, cadmium and strychnine. The sensitivity of this assay approach and implications of the experimental findings for environmental threat detection are discussed.