Nonenzymatic Sensor for Lactate Detection in Human Sweat

For noninvasive diagnostics of hypoxia, we propose the nonenzymatic sensor based on screen-printed structures with the working surface modified in course of electropolymerization of 3-aminophenylboronic acid (3-APBA) with imprinting of lactate. Impedimetric sensor allows lactate detection in the range from 3 mM to 100 mM with the detection limit of 1.5 mM; response time is 2-3 min. Sensor sensitivity remains unchanged within 6 months of storage unpacked in dry state at a room temperature, which is unachievable for enzyme based devices. Analysis of human sweat with poly(3-APBA) based sensor is possible due to (i) much higher lactate content compared to other polyols and (ii) high sensor selectivity (K_lactate^glucose < 3 × 10^-2). Successful detection of lactate in human sweat by means of the poly(3-APBA) based sensor has been confirmed using the highly specific reference method based on lactate oxidase enzyme (correlation coefficient r > 0.9). The attractive performance characteristics of poly(3-APBA) based enzyme-free sensors justify their future use for noninvasive clinical analysis and sports medicine.