Design and optimization of a lactate amperometric biosensor based on lactate oxidase cross-linked with polymeric matrixes

The design and characterization of a lactate biosensor is described. The biosensor is developed through the immobilization of lactate oxidase (LOD) in an albumin and mucin composed hydrogel. The enzyme is then cross-linked with glutaraldehyde to the polymeric matrix and entrapped between two polycarbonate membranes. The hydrogen peroxide produced by the reaction of lactate and LOD is detected on a Pt electrode operated at 0.65 V versus Ag vertical bar AgCl. The performance of the biosensor was evaluated in matrixes with different amounts of albumin, mucin and glutaraldehyde. The response time of the sensor to 10 mu M lactate required 90 s to give a 100% steady-state response of 0.079 mu A. Linear behavior was obtained for 0.7 mu M < c(Lac) < 1.5 mM. The detection limit calculated from the signal to noise ratio was 0.7 mu M. Only 0.1 U of enzyme was necessary to get a biosensor with a relatively high current flow and an excellent stability over a storage period of 30 days. High reproducibility in the response was obtained when several biosensors were prepared with the same composition. (c) 2008 Elsevier B.V. All rights reserved.