Layered composites of PEDOT/PSS/nanoparticles and PEDOT/PSS/phthalocyanines as electron mediators for sensors and biosensors

Abstract

The sensing properties of electrodes chemically modified with PEDOT/PSS towards catechol and hydroquinone sensing have been successfully improved by combining layers of PEDOT/PSS with layers of a secondary electrocatalytic material such as gold nanoparticles (PEDOT/PSS/AuNPs), copper phthalocyanine (PEDOT/PSS/CuPc) or lutetium bisphthalocyanine (PEDOT/PSS/LuPc2). Layered composites exhibit synergistic effects that strongly enhance the electrocatalytic activity as indicated by the increase in intensity and the shift of the redox peaks to lower potentials. A remarkable improvement has been achieved using PEDOT/PSS/LuPc2, which exhibits excellent electrocatalytic activity towards the oxidation of catechol. The kinetic studies demonstrated diffusion-controlled processes at the electrode surfaces. The kinetic parameters such as Tafel slopes and charge transfer coefficient (α) confirm the improved electrocatalytic activity of the layered electron mediators. The peak currents increased linearly with concentration of catechol and hydroquinone over the range of 1.5 × 10−4 to 4.0 × 10−6 mol·L−1 with a limit of detection on the scale of μmol·L−1. The layered composite hybrid systems were also found to be excellent electron mediators in biosensors containing tyrosinase and laccase, and they combine the recognition and biocatalytic properties of biomolecules with the unique catalytic features of composite materials. The observed increase in the intensity of the responses allowed detection limits of 1 × 10−7 mol·L−1 to be attained.

A different approach for the analysis of grapes: Using the skin as sensing element

“…In such sensors, the electrode surface is covered with a sensing material that facilitates the charge-transfer reactions between the electrode and the solution (Barroso, Santos-Alvarez, Delerue-Matos, & Oliveira, 2011;Durst, Baumner, Murray, Buck, & Andrieux, 1997;Ziyatdinova, Kozlova, & Budnikov, 2016). Many sensing materials have been used as chemical modifiers, for instance, carbon nanotubes, graphene, nanoparticles, porphyrins, phthalocyanines or conducting polymers among others (García-Hernández, García-Cabezón, Martín-Pedrosa, de Saja, & Rodríguez-Méndez, 2016).…”

Widening of the electroactivity potential range by composite formation – capacitive properties of TiO2/BiVO4/PEDOT:PSS electrodes in contact with an aqueous electrolyte

“…Moreover, due to the improvement of electrical properties, the Ti/TiO 2 :H/BiVO 4 :H electrode material could be further covered by conducting polymer prepared via electrodeposition. Beside many possible applications of conducting polymers like hole-transport material [63], electrochromic layers [64], electrochemical sensors [65] and gas sensors [66], a conducting polymer, particularly PEDOT, may be used as an electrode material for supercapacitors in both aqueous [67] and nonaqueous electrolytes [68].…”

Analysis of Phenolic Content in Grape Seeds and Skins by Means of a Bio-Electronic Tongue

“…The electrocatalytic effect was stronger in C-LuPc 2 electrode, where an important improvement on the reversibility of the peaks and simultaneously higher intensity currents of the peaks were observed. It can be related to strong π-π interactions between the bis-phthalocyanine and the aromatic structure of catechol that can enhance the electron transfer rate [54,55]. The electrocatalytic activity of NiONPs is associated with their porosity and the mixed valence state found on the nanoparticle surface [56] and it has been already observed in other carbon electrodes [35].…”