Electrochemical study of PEDOT-PSS-MDB-modified electrode and its electrocatalytic sensing of hydrogen peroxide

Poly(para toluene sulphonic acid) and gold nanoparticles modified glassy carbon electrode for simultaneous voltammetric sensing of xanthine and hypoxanthine

A voltammetric sensor has been developed for the individual as well as simultaneous determination of xanthine (XA) and hypoxanthine (HX) based on an electroactive-polymerised layer of para toluene sulphonic acid and gold nanoparticles composite modified glassy carbon electrode ([p(PTSA)]/AuNPs/GCE)]. Under optimized conditions, an enhancement in the oxidation currents with well-separated and well-resolved peak position and a lower shift in the peak potentials were observed. By square wave voltammetry, the simultaneous determinations of XA and HX were achieved in the linear ranges 6.00 × 10-4 M to 3.00 × 10-6 M and 5.00 × 10-4 M to 1.00 × 10-5 M with detection limits of 4.09 × 10-7 M and 4.10 × 10-7 M, respectively. The mechanistic aspects were unveiled from linear sweep voltammetric studies and found that the electrode processes were diffusion-controlled. Finally, the sensor was successfully employed for the simultaneous determination of spiked amount of XA and HX in synthetic urine and serum samples.

Platinum and palladium nanoparticles on boron-doped diamond for the electrochemical detection of hydrogen peroxide: a comparison study

Hydrogen peroxide (H2O2) plays a role in many facets - a household item, an important industrial chemical, a biomarker in vivo, and several others. For this reason, its measurement and quantification in a variety of media are important. While spectroscopic detection is primarily used for H2O2, electrochemical methods offer advantages in versatility, cost, and sensitivity. In this work, we investigate a 2-step surface metal nanoparticle (NP) modification for platinum (Pt) and palladium (Pd) on boron-doped diamond (BDD) electrodes for the detection of H2O2. Several parameters such as the metal salt concentration and electrodeposition charge in the 2-step modification were varied to find an optimum. Using cyclic voltammetry (CV), the BDD-PdNP electrode types were found to yield a sharper, more well-resolved H2O2 oxidation peak compared to the BDD-PtNP electrodes. Both metal NP electrode types significantly improved the response compared to the bare BDD electrode; a 150-200× improvement in sensitivity was observed across all modified electrode types. Calibration experiments were completed at both low and high concentration ranges in stagnant and flow-based solutions. The lowest limit of detection (LOD) obtained was 50 nM (5E-08 M) on a BDD-PdNP electrode modified with 1.0 mM PdCl2 to 5.0 mC in the wet chemical seeding and electrodeposition steps. 0.25 mM PdCl2 to 3.23 mC and 0.25 mM HPtCl6- to 3.23 mC also yielded a sufficient response for low-level H2O2, with LODs around 100 nM (1E-07 M). Overall, this work exemplifies the wide applicability of BDD and achieves sub-μM H2O2 LODs with a non-enzymatic electrode material.

Application of PEDOT:PSS and Its Composites in Electrochemical and Electronic Chemosensors

Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is a highly important and attractive conducting polymer as well as commercially available in organic electronics, including electrochemical and electronic chemosensors, due to its unique features such as excellent solution-fabrication capability and miscibility, high and controllable conductivity, excellent chemical and electrochemical stability, good optical transparency and biocompatibility. In this review, we present a comprehensive overview of the recent research progress of PEDOT:PSS and its composites, and the application in electrochemical and electronic sensors for detecting liquid-phase or gaseous chemical analytes, including inorganic or organic ions, pH, humidity, hydrogen peroxide (H2O2), ammonia (NH3), CO, CO2, NO2, and organic solvent vapors like methanol, acetone, etc. We will discuss in detail the structural, architectural and morphological optimization of PEDOT:PSS and its composites with other additives, as well as the fabrication technology of diverse sensor systems in response to a wide range of analytes in varying environments. At the end of the review will be given a perspective summary covering both the key challenges and potential solutions in the future research of PEDOT:PSS-based chemosensors, especially those in a flexible or wearable format.

GO/PEDOT:NaPSS modified cathode as heterogeneous electro-Fenton pretreatment and subsequently aerobic granular sludge biological degradation for dye wastewater treatment

Heterogeneous electro-Fenton (EF) technology has been wildly applied for the treatment of wastewater containing dyes and other organic pollutants. However, biologically treatment should be further applied after heterogeneous electro-Fenton process in order get better effluent quality. In the present study, a simple electropolymerization method using poly (3,4-ethylenedioxythiophene) (PEDOT) and graphene oxide (GO) was applied for graphite felt (GF) electrode modification as cathode in EF system, and coupling subsequently aerobic granular sludge (AGS) biological treatment for dye wastewater treatment. The modified electrode was characterized by scanning electron microscopy (SEM), Raman spectrum, and cyclic voltammetry (CV). Data implied that much higher H₂O₂ productivity, current response and coulomb efficiency (CE) were achieved by using GO/PEDOT:NaPSS modified GF. The results could be ascribed to the synergistic effect between PEDOT and GO that accelerated the electron transfer rate. Moreover, the H₂O₂ production capacity remained over 84.2% after 10-times reuses for GO/PEDOT:NaPSS modified GF, indicating that GO significantly improved the stability and life of electrode. Compared with the single system, the total organic carbon (TOC) and chemical oxygen demand (COD) removal efficiencies of the combined system degradation methylene blue (MB) wastewater were significantly improved. Therefore, this modified GF could be used as a potentially useful cathode in heterogeneous EF technology for actual wastewater treatment and the combined system have a promising engineering application value in MB wastewater degradation field.

Simultaneous determination of isoproterenol, acetaminophen, folic acid, propranolol and caffeine using a sensor platform based on carbon black, graphene oxide, copper nanoparticles and PEDOT:PSS

We explored the use of carbon black (CB), graphene oxide (GO), copper nanoparticles (CuNPs) and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) as electrode materials for the simultaneous determination of isoproterenol, acetaminophen, folic acid, propranolol and caffeine. The designed nanostructured surface was widely characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), contact angle measurements and electrochemistry. From electrochemical characterization assays carried out towards the potassium ferricyanide redox probe, fast electron transfer kinetics and a considerably higher electroactive surface area were observed for the modified electrodic surface based on CB, GO, CuNPs and PEDOT:PSS film. Using square-wave voltammetry (SWV), well defined and resolved anodic peaks were detected for isoproterenol, acetaminophen, folic acid, propranolol and caffeine, with peak-to-peak potential separation not less than 170 mV. Then, the SWV technique was explored for the simultaneous determination of quinary mixtures of these analytes, resulting in analytical curves with linear ranges and limits of detection at micromolar concentration levels. The practical viability of the proposed voltammetric sensor was illustrated in the analysis of human body fluid samples. The proposed sensor showed good repeatability and a successful application using urine and serum matrices, with recoveries close to 100%.

Immobilized redox mediators for electrochemical NAD(P)+ regeneration

The applicability of dissolved redox mediators for NAD(P)(+) regeneration has been demonstrated several times. Nevertheless, the use of mediators in solutions for sensor applications is not a very convenient strategy since the analysis is not reagentless and long stabilization times occur. The most important drawbacks of dissolved mediators in biocatalytic applications are interferences during product purification, limited reusability of the mediators, and their cost-intensive elimination from wastewater. Therefore, the use of immobilized mediators has both economic and ecological advantages. This work critically reviews the current state-of-art of immobilized redox mediators for electrochemical NAD(P)(+) regeneration. Various surface modification techniques, such as adsorption polymerization and covalent linkage, as well as the corresponding NAD(P)(+) regeneration rates and the operational stability of the immobilized mediator films, will be discussed. By comparison with other existing regeneration systems, the technical potential and future perspectives of biocatalytic redox reactions based on electrochemically fed immobilized mediators will be assessed.