An electrochemical sensor array and its application to real-time brain slice imaging

An electrochemical sensing system using a planar microelectrode array has been developed for monitoring biological molecules with relatively high spatial and temporal resolution. This allows noninvasive real-time imaging of biological molecules released from tissue. In this study, we establish a multichannel hydrogen peroxide (H₂O₂) sensing system to monitor the real-time H₂O₂ distribution in tissue using a planar sensor array. H₂O₂ is known to be associated with the pathology of neurological diseases because it is a by-product of degenerative reactions involving reactive oxygen species, which are a major cause of oxidative stress in mammalian cells. The sensor array is based on a 64-channel ITO electrode array composed of 50 × 50 μm electrodes modified with an enzyme (horseradish peroxidase) and an electron transfer mediator. We place a cultured rat hippocampal slice on the array and measure the current at each sensor using a multipotentiostat. When we introduce bicuculline into the solution as a stimulant in the presence of a catalase inhibitor, we can observe a distinct increase in the H₂O₂ concentration. This real-time H₂O₂ distribution monitoring system is a powerful tool with which to explore the neuronal cell death mechanism in biological systems.