Electro-catalytic Oxidation of Formaldehyde on Copper Electrode: a New Kinetics Model

Abstract Electro-catalytic oxidation of formaldehyde on copper electrode in 100 mM NaOH solution at different concentrations of formaldehyde was studied in the steady state polarization technique. The CV curve shows evidence for two processes occurring at the interface: one is associated with the formaldehyde electro-oxidation leading to formic acid formation on the surface and the other is assigned to the oxidation of formic acid that leads to CO 2 evolutions with low yield. Reaction orders for the faradic current on copper electrode have been determined as 0.21 for the higher and 0.76 for the lower concentration of formaldehyde. Reaction orders for CO 2 evolution during formaldehyde oxidation are 1.4 times higher in each case. Tafel slopes in the range of 140-160 mV are found. This signifies that the first reaction step involving the formation of adsorbed CO 2 is largely determining the overall reaction rate

Poly-dopamine-Beta-Cyclodextrin Modifi ed Glassy Carbon Electrode as a Sensor for the Voltammetric Detection of L-Tryptophan at Physiological pH

ABSTRACT The main purpose of this report was to develop application of poly-dopamine-beta-cyclodextrin modifi ed glassy carbon electrode (PDA-β-CD-GCE) towards electrooxidation and determination of L-Tryptophan (L-Trp) and also the evaluation its kinetic parameters. In continuation of our efforts to use PDA-β-CD-GCE for amino acids detection, our objective in the present work was to expand application of this sensor for the determination of L-Trp which is very sensitive

Poly-dopamine-Beta-Cyclodextrin Modified Glassy Carbon Electrode as a Sensor for the Voltammetric Detection of L-Tryptophan at Physiological pH

The main purpose of this report was to develop application of poly-dopamine-beta-cyclodextrin modified glassy carbon electrode (PDA-β-CD-GCE) towards electrooxidation and determination of L-Tryptophan (L-Trp) and also the evaluation its kinetic parameters. In continuation of our efforts to use PDA-β-CD-GCE for amino acids detection, our objective in the present work was to expand application of this sensor for the determination of L-Trp which is very sensitive

Graphene quantum dot modified glassy carbon electrode for the determination of doxorubicin hydrochloride in human plasma

Low toxic graphene quantum dot (GQD) was synthesized by pyrolyzing citric acid in alkaline solution and characterized by ultraviolet--visible (UV–vis) spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM), spectrofluorimetery and dynamic light scattering (DLS) techniques. GQD was used for electrode modification and electro-oxidation of doxorubicin (DOX) at low potential. A substantial decrease in the overvoltage (−0.56 V) of the DOX oxidation reaction (compared to ordinary electrodes) was observed using GQD as coating of glassy carbon electrode (GCE). Differential pulse voltammetry was used to evaluate the analytical performance of DOX in the presence of phosphate buffer solution (pH 4.0) and good limit of detection was obtained by the proposed sensor. Such ability of GQD to promote the DOX electron-transfer reaction suggests great promise for its application as an electrochemical sensor

Reduced graphene oxide decorated with gold nanoparticle as signal amplification element on ultra-sensitive electrochemiluminescence determination of caspase-3 activity and apoptosis using peptide based biosensor

Introduction: Growing demands for ultrasensitive biosensing have led to the development of numerous signal amplification strategies. In this report, a novel electrochemiluminescence (ECL) method was developed for the detection and determination of caspase-3 activity based on reduced graphene oxide sheets decorated by gold nanoparticles as signal amplification element and horseradish peroxidase enzyme (HRP) as ECL intensity enhancing agent. Methods: The ECL intensity of the luminol was improved by using the streptavidin coated magnetic beads and HRP in the presence of hydrogen peroxide. The cleavage behavior of caspase-3 was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques using biotinylated peptide (DEVD containing peptide) which was coated on reduced graphene oxide decorated with gold nanoparticle. The surface modification of graphene oxide was successfully confirmed by FTIR, UV-vis and x-ray spectroscopy. Results: ECL based biosensor showed that the linear dynamic range (LDR) and the lower limit of quantification (LLOQ) were 0.5-100 and 0.5 femtomolar (fM), respectively. Finally, the performance of the engineered peptide based biosensor was validated in the A549 cell line as real samples. Conclusion: The prepared peptide based biosensor could be considered as an excellent candidate for early detection of apoptosis, cell turnover, and cancer related diseases