Carbon-Fiber Microbiosensor for Monitoring Rapid Lactate Fluctuations in Brain Tissue Using Fast-Scan Cyclic Voltammetry

Abstract

Recent studies have described a role for lactate in brain energy metabolism and energy formation, challenging the conventional view that glucose is the principle energy source for brain function. To date, lactate dynamics in the brain are largely unknown, limiting insight into function. We addressed this by developing and characterizing a lactate oxidase-modified carbon-fiber microelectrode coupled with fast-scan cyclic voltammetry. This new tool boasts a sensitivity for lactate of 22 ± 1 nA•mM −1 and LOD of 7.0 ± 0.7 μM. The approach has enabled detection of rapid lactate fluctuations with unprecedented spatiotemporal resolution as well as excellent stability, selectivity, and sensitivity. The technology was characterized both in vitro and in vivo at discrete recording sites in rat striatum. We provide evidence that striatal lactate availability increases biphasically in response to electrical stimulation of the dopaminergic midbrain in the anesthetized rat. This new tool for real-time detection of lactate dynamics promises to improve understanding of how lactate availability underscores neuronal function and dysfunction.

Fiber-based lactate recordings with fluorescence resonance energy transfer sensors by applying an magnetic resonance-informed correction of hemodynamic artifacts

“…However, this was not the case for our study since the fluorescence signals had slow dynamics in all experiments. The half decay time of Twitch-2B is 2.8 s. 67 Further, the response of cerebral lactate to electrical stimulation is on the timescale of seconds, 14 , 15 and finally, a very slow but constant signal change is expected for phFRET upon a 3-min injection. For other fluorescence recordings with fast kinetics (e.g., calcium imaging with GCaMP6f 68 ), line scanning MRI could be used for correction, enabling temporal resolutions of 50 ms. 69 , 70 …”

“… 7 Cerebral lactate can be detected by using magnetic resonance spectroscopy (MRS), 8 – 10 microdialysis, 11 – 13 or cyclic voltammetry. 14 , 15 However, only a bulk signal or extracellular lactate can be measured using these methods. In addition, for MRS and microdialysis, only a low temporal resolution is achievable.…”

Drift Subtraction for Fast-Scan Cyclic Voltammetry Using Double-Waveform Partial-Least-Squares Regression

“…Fast-scan cyclic voltammetry (FSCV) at carbon-fiber microelectrodes (CFME) is a powerful method for assessing rapid neurochemical dynamics in biological preparations ranging from single cells to freely moving animals. − When combined with pharmacological or behavioral paradigms, this approach has provided remarkable insight into the molecular mechanisms underlying goal-directed behavior. − Scan rates in the hundreds of volts per second range have allowed sensitive, real-time measurements with molecular specificity for a wide variety of both electroactive and nonelectroactive (through enzyme-modified electrodes) neurochemicals. − However, the rapid scan rates generate charging currents that dwarf the faradaic currents generated by target analytes. This necessitates the use of background subtraction to reveal faradaic currents generated by neurochemicals present at the electrode surface.…”

3D Fuzzy Graphene Microelectrode Array for Neurotransmitter Sensing at Sub-cellular Spatial Resolution

“…The theoretical lower detection limit (LOD), defined as 3 times the standard deviation of the noise, (Harris 2010;Schmidt et al 2013;Smith et al 2018;Swamy and Venton 2007b;Taylor et al 2017) was estimated to be 990 ± 15 pM (Mean ± SD, n = 5) for 50 x 50 µm 2 3DFG microelectrodes, which is the lowest LOD value reported in literature using FSCV with carbon-based materials for DA detection (Table 1). For 2 x 2 µm 2 3DFG microelectrodes the LOD is 3.6 ± 2.2 nM (Mean ± SD, n = 4), remaining one of the lowest reported LOD value using FSCV with carbon-based materials ( Table 1).…”