Silver nanostructures - poly(3,4-ethylenedioxythiophene) sensing material prepared by sinusoidal voltage procedure for detection of antioxidants

This work is focused on the investigation of a composite material based on silver nanoparticles (AgNPs) and poly(3,4-ethylenedioxythiophene) (PEDOT) as sensing element of an electrochemical sensor for the determination of caffeic acid (CA). The novelties of the present work lie on the in-situ electrodeposition of AgNPs upon PEDOT layer using a sinusoidal voltage (SV) approach and the application of the SV procedure to other conventional electrodes like glassy carbon electrode (GCE), besides the quartz crystal electrodes designed for gravimetric measurements. The SV method consists in the application of a sinusoidal voltage with selected frequency and amplitude over a constant potential. The PEDOT layer has also been prepared onto glassy carbon electrode by means of this SV method due to its benefits such as increased electroactive area and roughness of the deposited organic coating. The properties of the prepared Ag-PEDOT material were investigated by electrochemical methods and scanning electron microscopy. The role of nitrate doping ions in the electrocatalytic properties of the proposed Ag-PEDOT sensing material toward caffeic acid is demonstrated by an increased analytical performance. The sensor displayed good analytical performance in terms of detection limit, linear response range, and sensitivity. Finally, the Ag-PEDOT-based electrochemical sensor was applied successfully in the analysis of pear and orange juice samples to assess the total polyphenols content expressed in equivalents of caffeic acid.