A Bird’s Eye View of Lactate Biosensors

Lactic acid (2-Hydroxypropanoic acid) or lactate (ionic form of lactic acid) is generated from pyruvic acid under anaerobic condition in all tissues like skeletal muscle, brain, RBC and kidney. The normal level of lactic acid in serum is in the range of 0.5-2.2 mM. During exercise and extensive work, its level in blood increases upto 12 mM and 25 mM. Lactate level is measured in dairy products to monitor the freshness, stability and quality of foods. It is also measured in alcoholic beverages to examine their acidity and tartness. Blood lactate level provides valuable information of stress in marine products/fish culture industry. Determination of serum lactate is required in the differential diagnosis and medical management of hyperlactemia, cardiac arrest and resuscitation sepsis, reduced renal excretion, hypoxia induced cancer, decrease extra hepatic metabolism, intestinal infarction and lactic acidosis. Among the various methods available for determination of lactate, biosensing method is comparatively simple, sensitive, selective, rapid and economical. A biosensor is an analytic device, employing a biological recognition element, which is in the direct spatial contact with the transducer element. The review article describes the classification of various lactate biosensors, their principle, merits and demerits [1]. As per this classification, lactate biosensors have been divided into 5 major classes: (i) Electrochemical, (ii) Electrochemiluminescence, (iii) Fluorescence, (iv) Microband and (v) Reagent-less biosensors.