A Prussian Blue Modified Electrode Based Amperometric Sensor for Lactate Determination

Lactate is a significant indicator in sports and clinical medicine, which is useful to evaluate and diagnose the health status related to oxygen deficit situations and lactic acidosis. The development of lactate biosensors have become a major growth area for noninvasive and real-time monitoring towards maintaining performance and human health status. In the present study, a Prussian Blue modified electrode-based amperometric enzymatic biosensor is one of the promising devices for continuous lactate monitoring. The working electrode of the screen-printed carbon electrode was prepared under optimal conditions with gold nanoparticle (AuNP), Prussian Blue (PB), and lactate oxidase (LOx) enzyme followed by nafion. The determination of lactate was performed using chronoamperometry with the optimal operating potential for hydrogen peroxide $\left(\mathrm{H}_{2} \mathrm{O}_{2}\right)$ (0 V versus $\mathrm{Ag} / \mathrm{AgCl}$ reference electrode). The lactate calibration curve showed a linear response in the wide concentration range between $5 \times 10^{-6}$ and $1 \times 10^{-3} \mathrm{M}$. The analytical accuracy and precision (CV%) of this lactate biosensor were 98.89 % and 1.68-3.96 %, respectively. Furthermore, irrelevant analytes and other substances which might appear in sweat were applied as a negative control to present the non-specific interaction between enzyme and substrate reaction. This study shows the success of the amperometric sensor system for lactate determination and can be used to develop for further study as a rapid response and portable point of care device.