Pirarubicin determination with impedimetric and voltammetric DNA sensors based on poly(Nile Blue) electropolymerized from deep eutectic solvents

The phenoxazine dye Nile Blue electropolymerized from the deep eutectic solvents (DESs), reline and oxaline, was used for the first time as a constituent of DNA sensors for voltammetric and impedimetric determination of the anthracycline medication pirarubicin. An electropolymerization process was performed in potentiodynamic mode on the surface of a single-use screen-printed carbon electrode. DNA was applied on the polymer coatings obtained, and its subsequent interaction with the analyte was characterized. Sensors based on different studied coatings demonstrated various linear concentration ranges and low limits of detection (down to the femtomolar level). The voltammetric approach allowed pirarubicin to be determined with a limit of detection of 10 pM for the coating obtained from aqueous medium and 1 fM for both coatings from reline and oxaline. For the impedimetric method, the limit of detection for pirarubicin was 50 pM for the coating from aqueous medium, and 0.1 fM and 0.05 fM for the coatings from reline and oxaline, respectively. The sensor based on the coating from reline showed the best analytical characteristics and reproducibility, enabling its use for the analysis of real samples.