Laser-Induced Graphene-Based Platforms for Dual Biorecognition of Molecules

Expanding the single molecule detection, enabled by laser-induced graphene (LIG) technology, for portable and on-site analysis, a dual molecule system with a two-working-electrode architecture was developed for ascorbic acid (AA) and amoxicillin (AMOX) detection, which are currently used in aquaculture and persist as water contaminants. The biorecognition element of each target compound was a suitable molecularly imprinted polymer (MIP). The AMOX MIP was developed herein for the first time and assembled by electropolymerization of eriochrome black T (EBT). It showed a wide linear response from 50 nM to 100 μM, with a sensitivity of −13.32 μA/decade. Calibration curves revealed good squared correlation coefficients (R2 > 0.99) with a limit of detection (LOD) of 11.98 nM. AA MIP was assembled according to a previous work reported in the literature, displaying a linear response from 1.5 to 4 mM and a sensitivity of 1.356 μA/decade. The developed dual-LIG device was further tested in real samples and successfully applied to the analysis of binary mixtures prepared in environmental water samples from a well. Overall, the proposed device allows in situ analysis of two different molecules and holds an exceptionally low-cost design when compared to competing architectures in the literature, and the fabrication method here employed offers the possibility of easily adjusting the desired architecture on demand.