A portable system for photoelectrochemical detection of lactate on TiO2 nanoparticles and [Ni(salen)] polymeric film

In this paper we present a portable photoelectrochemical system developed with screen-printed carbon electrodes (SPCEs) and a 3 W light-emitting diode (LED). The device with 3D printed structure was applied for detecting lactate on TiO2 nanoparticles modified with {[}Ni(salen)] polymer film (referred to as TiO2@poly{[}Ni (salen)]). Electrode coating with the polymer increased the sensitivity of the photoelectrochemical sensor, resulting in a linear range from 0.1 to 20 mmol L-1 with a limit of detection (LOD) of 88 mu mol L-1. The sensing system exhibited excellent stability, reproducibility, and selectivity. We also demonstrated by in situ Fouriertransform infrared spectroscopy (FTIR) measurements that carbon dioxide (CO2) is the main product from photoelectrooxidation of lactate on TiO2@poly{[}Ni(salen)]. The portable system can be employed with any type of modified electrodes to function as photoelectroanalytical (bio)sensors, especially for point-of-care diagnostics. (AU)