Microelectrode Biosensors for Real-Time Monitoring Lactate Trafficking in the Extracellular Space of Brain Tissue

ELIANA FERNANDES; MATIAS REGIART; ANDRÉ T. VICENTE; CÂNDIDA DIAS; ANA LEDO; RUI M. BARBOSA.

Congreso; 72nd Annual Meeting of the International Society of Electrochemistry; 2021

International Society of Electrochemistry

In the brain tissue, lactate is the predominant glycolytic product trafficked between the distinct cell types and besides its role as a metabolic substrate, it has also been shown to act as an intercellular signaling molecule. Hence, monitoring extracellular lactate concentrations is of surmount importance to understanding its role in brain physio(patho)logy. Microbiosensors coupled with fast electrochemical techniques have emerged as an important analytical tool for monitoring the concentration dynamics of nonelectroactive neurotransmitters and metabolic substrates such as lactate in the brain extracellular space with high spatial and temporal resolution and minimal tissue damage.In the present work, microelectrode-based biosensors have been designed and developed using ceramic-based microelectrode arrays (MEA) and platinum nanoparticle-modified carbon fiber microelectrodes (CFM) platforms for the detection and monitoring of lactate with high spatial-temporal resolution. Lactate oxidase (LOx) was immobilized on the electrode surface using the cross-linking agent glutaraldehyde or chitosan. The microbiosensors were further coated with a layer of polyurethane (PU), to extend linear range for the substrate quantification. The enzyme loading, BSA concentration and the PU layer properties were optimized. Morphological characteristics and electroanalytical performance of the microbiosensors were assessed, respectively, by scanning electron microscopy and electrochemical techniques. Prior to insertion into the rat brain microbiosensors were coated with an exclusion layer of meta-phenylenediamine (m-PD) by electropolimerization in order to minimize the interference of undesired compounds such as ascorbate. The microbiosensors were successfully used for detection and monitoring of lactate with high temporal and spatial resolution in ex vivo and in vivo in response to stimulated changes in lactate concentration.