Biosensors Based On Prussian Blue Modified Carbon Fibers Electrodes for Monitoring Lactate in The Extracellular Space of Brain Tissue

During recent decades, a new paradigm has emerged in neuroscience from growing evidence that lactate, and not glucose, has the more important role as an energy substrate during neural activation. Based on these findings, the astrocyte–neuron–lactate shuttle hypothesis (ANLSH) has been proposed. Over the same period, biosensors have become an important tool for in-vivo studies, providing higher time and spatial resolution over microdialysis and other neuroanalytical techniques. In this work we present a new lactate microbiosensor based on Prussian Blue (PB)-modified carbon fiber electrodes (CFEs) that allows the detection of enzyme-generated hydrogen peroxide at a low applied potential (~0 V against SCE), contrasting the high overpotential used in many previous designs based on platinum transducers (~0.7 V). Here, optimization of the fabrication procedure is described, including activation of CFE/PB, enzyme immobilization, anti-biofouling and anti-interference properties. Finally, to illustrate the potential use of this approach, some in-vivo results are presented, including pharmacological, physiological and electrophysiological stimulation, showing that this microbiosensor design is well suited to exploring the role of lactate in brain extracellular fluid.