Meldola's blue is a biosensor for the measurement of lactate in serum has been developed, which is based on a screen-printed carbon electrode, modified with Meldola's Blue-Reinecke Salt (MBRS-SPCE), coated with the enzyme lactate dehydrogenase NAD+ dependent (from Porcine heart), and NAD+. A cellulose acetate layer was deposited on the top of the device to act as a permselective membrane.