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 μmol L−1. The sensing system exhibited excellent stability, reproducibility, and selectivity. We also demonstrated by in situ Fourier-transform 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.