Study Of L-lactate Biosensor Based On Graphene

L-lactate, a key product produced by anaerobic metabolism, plays an important role in sports medicine and clinical diagnosis. In this regard, constructing an L-lactate biosensor with low-cost and quick-response is very necessary. Graphene, a material with large surface-to-volume ratio, excellent electrical conductivity and good biocompatibility, has attracted increasing attention for applications in the field of electrochemical sensors and biosensors. This work aims to construct a low-cost L-lactate biosensor based on screen printed electrode (SPCE), meanwhile, to use the excellent conductivity of graphene to enhance the performance of the L-lactate biosensor.In this work, a normal L-lactate biosensor without modifying graphene was constructed. The manufacturing process and working conditions were optimized. The performance of the L-lactate biosensor, including sensitivity, linearity, repeatability and selectivity, were tested. In the experiments, the L-lactate biosensor showed a sensitivity of 1.85μA·mM-1, a linear range of 1mM to 15mM, a detection limit of 0.63mM, a good repeatability and good selectivity. These good features basically met the requirements in the point-of-care testing application.Besides, a graphene modified SPCE was manufactured, on which a graphene modified L-lactate biosensor was then constructed. The method to modify the graphene on the SPCE was determined and the corresponding manufacturing process was also optimized. Using the scanning electron microscope(SEM) and cyclic voltammetry(CV), the performance of graphene modified SPCE was examined. The result indicated that graphene enhanced the electron transfer speed of the SPCE. Based on graphene modified SPCE, a graphene modified L-lactate biosensor was constructed. The manufacturing process and working conditions were optimized. The testing results indicated that graphene modified L-lactate biosensor showed an enhanced sensitivity of 2.38μA·mM-1. The biosensor also had a short response time(10s), a good repeatability, a wide linear range of 0.5mM to 15mM with a detection limit of 0.06mM.According to the comparison of the two kinds of L-lactate biosensors, it can be determined that modifying graphene can enhance the sensitivity, shorten the response time and improve the repeatability, but the selectivity will be reduced.