Development of Amperometric Lactate Biosensor Modified with Pt-black Nanoparticles for Rapid Assay

For point-of-care determination, a disposable biosensor for the analysis of L-lactate in athletes' serum samples was developed and optimized. The planar electrochemical biosensor was fabricated with gold thin-film two-electrode system and was modified with platinum-black nanoparticles and ferricyanide mediator. Platinum-black nanoparticles were deposited on the electrodes to improve the sensitivity and stability. Lactate oxidase (LOD, E.C.1.1.3.2) was immobilized on working electrodes with ferricyanide as mediator to improve the electron transfer ability by lowering the work potential to +0.2 V. The optimizations of the deposition of platinum-black nanoparticles, concentration of LOD, and concentration of ferricyanide in this article have resulted in the development of a lactate electrode with a wide linear range of 1–20 mM lactate, a high sensitivity of 1.43 µA mM−1, a fast detection time of 50 s, and a coefficient variation (CV) of 0.0549. The activity of biosensor held above 90% after one year storage at room temperature. The biosensor was successfully applied to the determination of L-lactate in serum samples without dilution. This disposable biosensor combined with portable meter is promising for rapid determination of point-of-care lactate.