Electrocatalysis and sensitive determination of cysteine at poly(3,4-ethylenedioxythiophene)-modified screen-printed electrodes

Nano-engineered screen-printed electrodes: A dynamic tool for detection of viruses

There is a growing interest in the development of portable, cost-effective, and easy-to-use biosensors for the rapid detection of diseases caused by infectious viruses: COVID-19 pandemic has highlighted the central role of diagnostics in response to global outbreaks. Among all the existing technologies, screen-printed electrodes (SPEs) represent a valuable technology for the detection of various viral pathogens. During the last five years, various nanomaterials have been utilized to modify SPEs to achieve convincing effects on the analytical performances of portable SPE-based diagnostics. Herein we would like to provide the readers a comprehensive investigation about the recent combination of SPEs and various nanomaterials for detecting viral pathogens. Manufacturing methods and features advances are critically discussed in the context of early-stage detection of diseases caused by HIV-1, HBV, HCV, Zika, Dengue, and Sars-CoV-2. A detailed table is reported to easily guide readers toward the "right" choice depending on the virus of interest.

Effect of Ionic Liquids on the Physical Properties of the Newly Synthesized Conducting Polymer

Conducting polymer has many applications in electronics, optical devices, sensors, and so on; however, there is still a massive scope of improvement in this area. Therefore, towards this aim, in this study, we synthesized a new thiophene-based conducting polymer, 2-heptadecyl-5-hexyl-6-(5-methylthiophen-2-yl)-4-(5-((E)-prop-1-enyl)thiophen-2-yl)-5H-pyrrolo[3,4-d]thiazole (HHMPT). Further, to increase its application, the interactions between the conducting polymer (HHMPT) and ionic liquids (ILs) were investigated by UV-Vis spectroscopy, FTIR spectroscopy, and confocal Raman spectroscopy techniques. Moreover, film roughness and conductivity of the polymer film with or without ILs were also studied. The imidazolium- and ammonium family ILs with the potential to interact with the newly synthesized conducting polymer were used. The results of the interaction studies revealed that the imidazolium family IL-polymer mixtures and ammonium family IL-polymer mixtures have almost similar conductivity at low concentration of ILs. This study provides an insight into the combined effect of a polymer and ILs and may generate many theoretical and experimental opportunities.

Simultaneous voltammetric detection of dopamine, ascorbic acid and uric acid using a poly(2-(N-morpholine)ethane sulfonic acid)/RGO modified electrode

A poly(2-(N-morpholine) ethane sulfonic acid)/reduced graphene oxide (RGO) modified glassy carbon electrode (GCE) was prepared using an electropolymerization method, and was characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The electrochemical behaviors and simultaneous detection of ascorbic acid (AA), dopamine (DA) and uric acid (UA) at this electrode were studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Tests showed that this electrode exhibited excellent electrocatalytic activity towards the oxidation of AA, DA and UA. The oxidation peak currents of AA, DA and UA were proportional with their concentrations in the ranges 1.0 μM-30 μM (30 μM-100 μM), 0.05 μM-100 μM and 0.1 μM-100 μM, with detection limits of 0.43 μM, 0.0062 μM and 0.056 μM, respectively. In addition, this electrode exhibited an excellent selectivity, reproducibility and stability, and has been successfully used to determine real samples with satisfactory results.

A rational design for the selective detection of dopamine using conducting polymers

A conducting polymer for the selective detection of dopamine has been designed by combining experimental measurements and theoretical calculations.

Polythiophenes and polythiophene-based composites in amperometric sensing

This overview of polythiophene-based materials provides a critical examination of meaningful examples of applications of similar electrode materials in electroanalysis. The advantages arising from the use of polythiophene derivatives in such an applicative context is discussed by considering the organic conductive material as such, and as one of the components of hybrid materials. The rationale at the basis of the combination of two or even more individual components into a hybrid material is discussed with reference to the active electrode processes and the consequent possible improvements of the electroanalytical performance. In this respect, study cases are presented considering different analytes chosen among those that are most frequently reported within the classes of organics and inorganics. The use of a polythiophene matrix to stably fix biological elements at the electrode surface for the development of catalytic biosensors and genosensors is also discussed. Finally, a few possible lines along which the next research in the field could be fruitfully pursued are outlined. Furthermore, the work still to be done to exploit the possibilities offered by novel products of organic synthesis, even along paths already traced in other fields of electrochemistry, is discussed.

Spectrophotometric determination of cysteine with gold nanoparticles stabilized with single-stranded oligonucleotides

A sensitive and selective spectrophotometric detection method for cysteine has been established in this paper. The assay is based on the displacement of single-stranded oligonucleotide (ssDNA) adsorbed on the surface of citrate-capped gold nanoparticles (AuNPs) by cysteine in 2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid buffer solution (pH 7.2) and on the phenomenon of salt-induced AuNPs aggregation. Upon addition of cysteine, the red-to-blue color changes of the ssDNA-stabilized AuNPs associated with aggregation under high-salt conditions were easily observed with the naked eye. The absorption ratio at 520 and 600 nm was herein employed to quantify the AuNPs aggregation process. The calibration curve showed that the absorption ratio increased linearly over the concentration range of 0.1-1.3 microM with a limit of detection of 100 nM. Subsequently, the assay was successfully employed to determine cysteine in artificial and pharmaceutical injection samples.