Screen-Printed Electrodes Based on Conductive Inks of Polyaniline/Graphene Hybrids and Their Application to Progesterone Detection

Abstract

Screen-printed electrodes (SPEs) were produced using conductive inks based on hybrids of polyaniline (PAni) and reduced graphene oxide (rGO). Cyclic voltammetry (CV) showed peaks characteristic of the PAni redox behavior in acidic media for all the modified SPEs. Electrochemical impedance spectroscopy (EIS) showed a significant decrease in the charge-transfer resistances, from 930 Ω for SPE/G:PAni to 544 Ω for SPE/G:PAni-rGO1 and to 303 Ω for SPE/G:PAni-rGO2 with just 0.06% and 0.12% in mass of rGO, respectively, in the final mass composition of the conductive inks. The SPEs were evaluated in the determination of progesterone (P4) hormone in neutral medium (phosphate buffer solution, pH 7.0). The CV results showed higher current signals at SPE/G:PAni-rGO1 compared with SPE/G and SPE/G:PAni, indicating a synergistic effect of PAni-rGO1 in the determination of P4. EIS also showed significant changes in the electrochemical double-layer capacitances in the presence of P4. The limits of detection (LOD) and quantification (LOQ) were, respectively, 211 nmol l−1 and 703 nmol l−1. This method is a simple, scalable and low-cost alternative for the fabrication of electrodes based on PAni-rGO hybrids, with synergic properties, aiming for future applications in sensors.