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A Graphene-Based Enzymatic Biosensor Using a Common-Gate Field-Effect Transistor for L-Lactic Acid Detection in Blood Plasma Samples

“…Lactate is present in various biological processes and medical conditions, and it has an important role in the anaerobic metabolic pathway [ 1 , 2 ]. Usually, the lactate concentration increases when there is a deficit of oxygen [ 1 , 3 , 4 ]. It also can be related to higher energy demand and it is a common target for monitoring of physical exercise routine [ 5 ].…”

“…Most of the reported biosensors used to detect lactate concentration depend on a specific enzyme to catalyze the reaction and enhance the selectivity; the product of the reaction is usually proportional to the analyte concentration [ 1 , 5 , 8 , 9 , 10 , 11 ]. Lactate oxidase (LOx) and lactate dehydrogenase (LDH) are the most common enzymes used as catalysts to bind the reactant molecule and catalyze the enzymatic reaction resulting in the product molecule [ 3 , 5 , 9 , 12 , 13 , 14 , 15 ]. The lactate oxidase enzyme is responsible for the production of pyruvate and hydrogen peroxide through the catalyzation of lactate and oxygen [ 12 , 16 , 17 ].…”

“…However, the LOx is unstable since it loses its activity in a short time [ 8 , 18 ]. Contrastingly, the lactate dehydrogenase enzyme catalyzes lactic acid into pyruvic acid [ 2 , 3 , 19 ]. In anaerobic metabolism, pyruvic acid is converted to lactic acid when there is a deficit of oxygen during the glycolysis process [ 3 ].…”

“…Contrastingly, the lactate dehydrogenase enzyme catalyzes lactic acid into pyruvic acid [ 2 , 3 , 19 ]. In anaerobic metabolism, pyruvic acid is converted to lactic acid when there is a deficit of oxygen during the glycolysis process [ 3 ]. However, the lactate dehydrogenase enzyme can act over other substrate molecules in certain conditions, increasing the final product [ 3 , 19 ].…”

“…In anaerobic metabolism, pyruvic acid is converted to lactic acid when there is a deficit of oxygen during the glycolysis process [ 3 ]. However, the lactate dehydrogenase enzyme can act over other substrate molecules in certain conditions, increasing the final product [ 3 , 19 ]. Considering this, it is necessary to block the substances in body fluids that can cause interference in the signal response, resulting in false-positive results.…”