Advancement in electrochemical strategies for quantification of Brown HT and Carmoisine (Acid Red 14) From Azo Dyestuff class.

Brown HT and carmoisine, which are the most used dyestuffs in pharmaceuticals, textiles, cosmetics and foods, are important components of the Azo family. Although the Azo group is not toxic or carcinogenic under normal conditions, these dyestuffs require great care due to the reduction of the Azo functional group to amines. In particular, fast, reliable, easy, on-site and precise determinations of these substances are extremely necessary and important. In this review, the properties, applications, and electrochemical determinations of brown HT and carmoisine, which are used as synthetic food colorants, are discussed in detail. Up to now, sensor types, detection limits (LOD and LOQ), and analytical applications in the developed electrochemical strategies for both substances were compared. In addition, the validation parameters such as the variety of the sensors, sensitivity, selectivity and electrochemical technique in these studies were clarified one by one. While the electrochemical techniques recommended for brown HT were mostly used for the removal of dyestuff, for carmoisine they included fully quantitative centered studies. The percentiles of voltammetric techniques, which are the most widely used among these electroanalytical methods, were determined. The benefits of a robust electrochemical strategy for the determination of both food colors are summed up in this review. Finally, the brown HT and carmoisine suggestions for future perspectives in electrochemical strategy are given according to all their applications.

Novel enzymatic graphene oxide based biosensor for the detection of glutathione in biological body fluids.

In this work, we report a novel enzymatic biosensor based on glutathione peroxidase (GSH-Px), graphene oxide (GO) and nafion for the electrochemical sensing of glutathione (GSH) in body fluids. GSH-Px was immobilized covalently via 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) onto modified glassy carbon electrode (GCE) decorated with GO and nafion and successfully used for sensing of GSH in the presence of H2O2 as catalyst with Michaelis-Menten constant about 0.131 mmol/L. The active surface are of GCE improve from 0.183 cm2 to 0.225 cm2 after modification with GO. The introduced biosensor (GSH-Px/GO/nafion/GCE) was used for monitoring of GSH over the range 0.003-370.0 µM, with a detection limit of 1.5 nM using differential pulse voltammetric (DPV) method. The GSH-Px/GO/nafion/GCE was successfully applied to the determination of GSH in real samples.

Doxorubicin Anticancer Drug Monitoring by ds-DNA-Based Electrochemical Biosensor in Clinical Samples.

In this research, glassy carbon electrode (GCE) amplified with single-wall carbon nanotubes (SWCNTs) and ds-DNA was fabricated and utilized for voltammetric sensing of doxorubicin with a low detection limit. In this technique, the reduction in guanine signal of ds-DNA in the presence of doxorubicin (DOX) was chosen as an analytical factor. The molecular docking study revealed that the doxorubicin drug interacted with DNA through intercalation mode, which was in agreement with obtained experimental results. The DOX detection performance of ds-DNA/SWCNTs/GCE was assessed at a concentration range of 1.0 nM-20.0 µM. The detection limit was found to be 0.6 nM that was comparable and even better (in many cases) than that of previous electrochemical reported sensors. In the final step, the ds-DNA/SWCNTs/GCE showed powerful ability for determination of the DOX in injection samples with acceptable recovery data.

A sensitive and fast approach for voltammetric analysis of bisphenol a as a toxic compound in food products using a Pt-SWCNTs/ionic liquid modified sensor.

A sensitive and fast approach has been introduced for the voltammetric sensing of bisphenol A based on modification of a paste electrode with Pt-SWCNTs and 1-ethyl-3-methylimidazolium n-butylsulfate as a highly conductive binder. The new sensor was used to determine the concentration of bisphenol A in food products in I-V mode. The Pt-SWCNTs nanocomposite was synthesized through the polyol method and its morphology was evaluated by field emission scanning electron microscopy, transmission electron microscopy and energy-dispersive X-ray spectroscopy techniques. The determining factors influencing the sensing performance, i.e., pH and mediators used in the modification process were optimized in the first step and the results showed that at a pH of 7.0, a modified paste containing 9% (w:w) nanocomposite and 20% (v:v) 1-ethyl-3-methylimidazolium n-butylsulfate formed catalytic properties enhancing the oxidation signal of bisphenol A by 5.9 folds. Current density investigation clearly confirmed the conductivity of Pt-SWCNTs and 1-ethyl-3-methylimidazolium n-butylsulfate in the paste matrix. In addition, fabricated sensor showed considerable sensing behavior for bisphenol A in the concentration range of 0.5 nM-180 µM with a detection limit of 0.2 nM. In the final step, using standard addition technique, the ability of fabricated sensor for sensing bisphenol A in food products was evaluated, and the results confirmed improved performance of the modified electrodes.