An ultrasensitive electrode modified with a molecularly imprinted PEDOT-TiO₂ nanocomposite for voltammetric atrazine...

Molecularly imprinted polymers (MIPs) have been studied to be used as a platform for electrochemical sensing devices, with special regard to the determination of pesticides. Due to MIP applicability, in the present research, we develop a glassy carbon electrode (GCE) modified with a molecularly imprinted nanocomposite based on the doping of poly(3,4-ethylenedioxythiophene) (PEDOT) with chitosan (Chit) and TiO₂ nanoparticles for sensing atrazine in environmental samples. The construction of the MIP nanocomposite was divided into four parts, which include the chitosan-TiO₂ layer formation by simple drop-casting on the GCE, the doping and electropolymerization of the Chit+TiO₂+PEDOT layer, cavity formation, and elution. The effectiveness of the film formation process was studied first by XRD and TEM analysis of the nanoparticles, and SEM and EDS analysis of the MIP. The doping of PEDOT was confirmed using cyclic voltammetry. Moreover, the performance of the MIP/GCE in the sensing activity was evaluated by voltammetry techniques. Analytical parameters reported values equal to 0.57 ± 0.01 nM, 1.92 ± 0.04 nM, and 6.63 nA/nM for the limit of detection (LOD), limit of quantification (LOQ), and sensitivity, respectively, in a linear range from 2.70 to 6.50 nM. The results were better than those of other electrochemical devices reported for atrazine determination. Furthermore, the stability, reproducibility, and repeatability of the device were evaluated, which reported excellent results after 28 days of use. Finally, the use of the sensing device was evaluated in spiked water samples, and the results obtained were compared with the ones obtained with UPLC-MS/MS analysis. The recovery percentage was 98.72 %. Overall, the composite formed by chitosan, TiO₂ nanoparticles, and PEDOT was an excellent modifier, enabling the sensing of atrazine in environmental samples even in the presence of high concentrations of other pesticides.