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

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 -5M L-lactate and a 3.7×10 -7M as limit of detection (LOD), and from 5×10 -6 to 5×10 -4M and 3.4×10 -6M, in case of LOx, respectively. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.