Molecularly Imprinted Sensor based on Ag-Au NPs/SPCE for Lactate Determination in Sweat for Healthcare and Sport Monitoring

This study presented fabrication of wearable amperometric lactate sensor based on molecularly imprinted polymer on Ag-Au nanoparticles (MIP/Ag-Au NPs) modified screen-printed carbon electrodes (SPCE) for sweat analysis in healthcare and sport monitoring. For modification of SPCE, the chemical synthesized Ag and Au NPs were spin-coated on SPCE, and MIPs electropolymerized on Ag-Au NPs/SPCE surface. Structural and morphological analyses by SEM, XRD and EDS confirmed that spherical Ag-Au nanoparticles were distributed homogeneously on the of MIP molecules. Electrochemical studies by CV and amperometry techniques indicated that the synergetic effect of the modification of the Ag-Au NPs with MIP particles were resulted in larger electroactive sites on the surface and improve the stability, selectivity and analytical signal because of their direct and fast electron transfer between a substrate and electrochemical ions. The linear range, detection limit and sensitivity of lactate sensor was obtained of 1-220 mu M, 0.003 mu M and 0.88066 mu A/mu M, respectively. The performance of the proposed flexible sensor was examined after applied mechanical forces and results demonstrated great durability and stability under the twisting and bending. MIP/Ag-Au NPs/SPCE sensor was attached to volunteers' skin for the monitoring of the lactate level during cycle exercise and obtained results suggested that MIP/Ag-Au NPs/SPCE as feasible and reliable wearable sensor can be used for continuously monitoring of lactate level in sweat.