Understanding the levels of glucose (G) and lactate (L) in blood can help us regulate various chronic health conditions such as obesity. In this paper, we introduced an enzyme-based electrochemical biosensor adopting glucose oxidase and lactate oxidase on two working screen-printed carbon electrodes (SPCEs) to sequentially determine glucose and lactate concentrations in a single drop (~30 µL) of whole blood. We developed a diet-induced obesity (DIO) mouse model for 28 weeks and monitored the changes in blood glucose and lactate levels. A linear calibration curve for glucose and lactate concentrations in ranges from 0.5 to 35 mM and 0.5 to 25 mM was obtained with R-values of 0.99 and 0.97, respectively. A drastic increase in blood glucose and a small but significant increase in blood lactate were seen only in prolonged obese cases. The ratio of lactate concentration to glucose concentration (L/G) was calculated as the mouse's gained weight. The results demonstrated that an L/G value of 0.59 could be used as a criterion to differentiate between normal and obesity conditions. With L/G and weight gain, we constructed a diagnostic plot that could categorize normal and obese health conditions into four different zones. The proposed dual electrode biosensor for glucose and lactate in mouse whole blood showed good stability, selectivity, sensitivity, and efficiency. Thus, we believe that this dual electrode biosensor and the diagnostic plot could be used as a sensitive analytical tool for diagnosing glucose and lactate biomarkers in clinics and for monitoring obesity.
Keywords: dual electrodes; electrochemical biosensor; glucose; lactate; obesity.