Fabrication of a novel sensor for lactate screening in saliva samples before and after exercise in athletes

Abstract

In this research, a chronoamperometric biosensor based on zinc oxide (ZnO)-graphene oxide (GO) nanocomposite material was designed and employed for lactate determination. The ZnO-GO hybrid proved to be a suitable substrate for the immobilization of lactate oxidase (LOD). The presence of ZnO and GO components in hybrid material led to synergistic effects and facilitates the LOD loading and electron transfer between the receptor and screen printed carbon electrode (SPCE) surface. The LOD-GO-ZnO modified SCPE exhibits excellent lactate sensing capabilities thanks to the uniform dispersion of ultrafine ZnO nanoparticles and enhanced mass-transfer kinetics. In phosphate buffer solution (pH=7.4), this novel electrochemical lactate biosensor demonstrates a linear response to lactate within the concentration range of 0.015–1.25 mM. Limit of detection (based on S/N=3) of the assay was estimated to be 9 µM. More importantly, the presence method is a highly selective device for the analysis of lactate in biological fluids. The lactate level in saliva samples was successfully measured before and after exercise of athletes using the suggested biosensor. This method offers a simple, cost-effective, fast, and effective platform for lactate determination in typical diagnostic applications.

Keywords

• Lactate sensor
• Nanocomposite
• Graphene
• Saliva sample
• Lactate oxidase