Abstract

Design of an Enzyme-free Microfluidic Electrochemical Biosensor for Lactate Detection Using NiO-NPs

Rohollah Nasiri, Postdoctoral Researcher, KTH Royal Institute of University

Detection and monitoring of the lactate in human body fluids and in vitro cell culture systems is crucial for studying metabolic disorders. Enzymatic lactate sensors suffer from low stability, poor reproducibility, and high cost. Non-enzymatic sensors take advantage of nanostructured-based electrodes by providing large surface area and high electrocatalytic efficiency which offer high stability, reproducibility, and without immobilization procedure. In this work, we designed an enzyme-free microfluidic electrochemical lactate sensor using screen printed electrodes. First, the working electrode was modified by drop-casting of NiO/Nafion dispersion and later the sensor performance was analyzed using cyclic voltammetry (CV) and amperometry. The CV showed an optimal working voltage of ~0.5V. Using amperometry the current response of the sensor for different concentrations of lactate at ~0.5V was determined. Results showed a linear calibration curve between the concentration of lactate and generated current. Later, we designed a microfluidic platform consisting of a micromixer to mix the cell culture media sample with electrolyte solution and integrated it to NiO-based lactate sensor to have a flow-through biosensor. We used the proposed sensor for lactate detection in the cell media for ketogenic diet-treated astrocytes and it showed good sensitivity, selectivity and being insensitive to common interferents. The proposed microfluidic lactate sensor is well-suited to be connected to organ-on-a-chip platforms for metabolic studies.