Enzymatic Strategies to Construct L-Lactate Biosensors Based on Polysulfone/Carbon Nanotubes Membranes

摘要

We present different strategies to construct amperometric L-lactate biosensors using the enzymes lactate dehydrogenase (LDH) and lactate oxidase (LOx). These biomolecules are incorporated into a polysulfone/carbon nanotubes composite matrix by means of an easy and rapid technique, i.e. inversion phase, and deposited onto carbon screen-printed electrodes. The use of redox mediators, Meldola's Blue and cobalt(II) phthalocyanine (CoPc) are necessary to reduce the working potential for the detection of NADH and H _2O _2 products. The working conditions for both biosensors have been optimized such as the pH, amount of immobilized enzyme and lifetime stability. LDH biosensor presents a linear interval range from 10 ~(-6) to 2×10 ~(-5)M L-lactate and a 3.7×10 ~(-7)M as limit of detection (LOD), and from 5×10 ~(-6) to 5×10 ~(-4)M and 3.4×10 ~(-6)M, in case of LOx, respectively.