A Novel Immobilization Enzyme Lactate Fluorescence Capillary Biosensor

Lactate dehydrogenase (LDH) was immobilized in inner surface of a medical capillary having 45 mm of length and 0.9 mm of inner diameter, and an immobilization enzyme lactate fluorescence capillary biosensor(IE-LFCBS) was made. Rapid microanalysis for lactate was realized by using it. When the IE-LFCBS sucked the mixture solution of coenzyme I(NAD(+)) and lactate in it, under catalysis of immobilized lactate dehydrogenase, NAD(+) reacted with lactate to form NADH, and then fluorescence intensity of NADH in the IE-LFCBS was determined at 353 nm of excitation and 466 nm of emission wavelengths to quantify lactate. Optimized experimental conditions suitable for the biosensor are as follows: the reaction time is 15 min, the experimental temperature is 38 degrees C, the concentrations of tris buffer (pH 8.8) and NAD(+) are 0.1 mol/L and 4.0 mmol/L, respectively; the concentration of LDH for immobilization is 60 kU/L. The determination range is from 1.0 to 5.0 mmol/L, the detection limit is 0.45 mmol/L, and the recovery is 95% - 98% with RSD <= 1.5% (n = 11). The biosensor has a good reproducibility, long-term stability, and can be used repeatedly. It can be applied for the rapid determination of lactate in ferment foodstuff, leechdom, blood samples and so on.