Electrochemical and optical bimodal sensing of caffeic acid based on electrodes made from nanorods of AuNPs:PEDOT:PSS and bio-hybrid chitosan:PEDOT:PSS†
Abstract
Caffeic acid (CA) is one of the electro-active phenolic compounds. Electrochemical sensors and optical sensors based on electrodes composed of PEDOT (poly(3,4-ethylenedioxy thiophene)):PSS, chitosan:PEDOT:PSS and nanorods of AuNPs:PEDOT:PSS were developed by a drop casting method on ITO (indium tin oxide) for the determination of CA in aqueous solutions. The developed interactions between the analyte and prepared electrodes were also analyzed by XPS studies. The fabricated electrodes were characterized by various spectroscopic techniques, namely UV-visible, FT-IR and XRD, and their surface morphology was investigated by SEM and TEM. The quantitative detection of CA was performed via an electrochemical technique, namely cyclic voltammetry (CV), and an optical technique using UV-visible spectroscopy. The cyclic voltammograms were recorded with the optimized parameters. CV allowed the detection of the analyte over a wide linear concentration range from 2 μmol dm−3 to 10 mmol dm−3. The sensing parameters, including the limit of detection (LOD), limit of quantification (LOQ) and sensitivity of each electrode, were determined through the plotted concentration calibration curves of CA for each technique. The acceptable values of recovery implied the feasibility of the sensors for practical applications.