Design and Evaluation of a Lactate Microbiosensor: Toward Multianalyte Monitoring of Neurometabolic Markers In Vivo in the Brain

Abstract

Direct in vivo measurements of neurometabolic markers in the brain with high spatio-temporal resolution, sensitivity, and selectivity is highly important to understand neurometabolism. Electrochemical biosensors based on microelectrodes are very attractive analytical tools for continuous monitoring of neurometabolic markers, such as lactate and glucose in the brain extracellular space at resting and following neuronal activation. Here, we assess the merits of a platinized carbon fiber microelectrode (CFM/Pt) as a sensing platform for developing enzyme oxidase-based microbiosensors to measure extracellular lactate in the brain. Lactate oxidase was immobilized on the CFM/Pt surface by crosslinking with glutaraldehyde. The CFM/Pt-based lactate microbiosensor exhibited high sensitivity and selectivity, good operational stability, and low dependence on oxygen, temperature, and pH. An array consisting of a glucose and lactate microbiosensors, including a null sensor, was used for concurrent measurement of both neurometabolic substrates in vivo in the anesthetized rat brain. Rapid changes of lactate and glucose were observed in the cortex and hippocampus in response to local glucose and lactate application and upon insulin-induced fluctuations of systemic glucose. Overall, these results indicate that microbiosensors are a valuable tool to investigate neurometabolism and to better understand the role of major neurometabolic markers, such as lactate and glucose.

Amperometric bio-sensing of lactate and oxygen concurrently with local field potentials during status epilepticus

“…The average biosensor sensitivity between 0.05 and 0.5 mM towards lactate was found to be 4.27 ± 1.35 nA mM −1 (n = 5). The results showed that the lactate microbiosensor exhibited comparable enzyme kinetics and analytical performance to previously described lactate microbiosensors [ 35 ].…”

Brain capillary pericytes are metabolic sentinels that control blood flow through a KATP channel-dependent energy switch

“…The glucose concentration in bulk cerebrospinal fluid is approximately 4 mM, 52 whereas parenchymal glucose has been measured in the range of approximately 0.3–2.3 mM. 53 – 66 Accordingly, we wondered whether subtle changes in local glucose concentration through this physiological range would influence the degree of K ATP channel activity and modulate pericyte membrane potential (Vm). To permit direct monitoring of pericyte Vm, we isolated capillaries from Cspg4 -DsRed mice with intact thin-strand pericytes, and measured Vm using sharp microelectrode impalements ( Figure 4A ).…”