An experimental and theoretical approach to electrochemical sensing of environmentally hazardous dihydroxy benzene isomers at polysorbate modified carbon paste electrode

Electrochemical polymerized DL-phenylalanine modified carbon nanotube sensor for the selective and sensitive determination of caffeic acid with riboflavin

In this study, DL-phenylalanine modified with a multiwall carbon nanotube paste electrode is used as advanced electrochemical sensor for analysing of 0.1 mM caffeic acid (CFA) with simultaneous detection of riboflavin (RFN). The developed sensors include electrochemically polymerized DL-phenylalanine (DL-PA) modified multiwall carbon nanotube paste electrode [DL-PAMMCNTPE] and bare multiwall carbon nanotube paste electrode [BMCNTPE]. The increasing stability in the developed electrochemical sensor for the quantification of CFA is highlighted in detail, along with its characterization using voltammetric techniques such as electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), differential pulse voltammetry (DPV), and linear Sweep Voltammetry (LSV). Scanning electron microscopy (SEM) technique was used to studied the structural analysis of BMCNTPE and DL-PAMMCNTPE surface. The investigation of 0.1 mM CFA in 0.2 M phosphate buffered solution (PBS) using a 7.0 pH at 0.1 V/s scan rate was highlighted using DL-PAMMCNTPE, which shows good electrochemical responses compared to BMCNTPE. This work characterizes the voltammetric responses by inspecting the pH effect, scan rate effect, and concentration difference of CFA at the DL-PAMMCNTPE surface. The CFA responses specify that the scan rate progress is adsorption controlled. The concentration of CFA detection was started from 20 μM to 600 μM using DPV method, with lower limit of detection (LOD) of 0.280 μM and limit of quantification (LOQ) of 0.936 μM. And for CV method concentration range 20 to 550 μM, with LOD of 0.198 μM and LOQ of 0.702 μM. Furthermore, the developed electrochemical sensor responses are shows good stability, repeatability, and reproducibility, for CFA. The analytical applicability of CFA in apple juice and coffee powder samples was also evaluated.

Facile synthesis of tantalum decorated on iron selenide with nitrogen-doped graphene hybrid for the sensitive detection of trolox in berries: Density functional theory interpretation

This work presents a hydrothermal method followed by a sonochemical treatment for synthesizing tantalum decorated on iron selenide (Ta/FeSe2) integrated with nitrogen-doped graphene (NGR) as a susceptible electrode material for detecting trolox (TRX) in berries samples. The surface morphology, structural characterizations, and electrochemical performances of the synthesized Ta/FeSe2/NGR composite were analyzed via spectrophotometric and voltammetry techniques. The GCE modified with Ta/FeSe2/NGR demonstrated an impressive linear range of 0.1 to 580.3 μM for TRX detection. Additionally, it achieved a remarkable limit of detection (LOD) of 0.059 μM, and it shows a high sensitivity of 2.266 μA μМ-1 cm-2. Here, we used density functional theory (DFT) to investigate the structures of TRX and TRX quinone and the locations of energy levels and electron transfer sites. The developed sensor exhibits significant selectivity, satisfactory cyclic and storage stability, and notable reproducibility. Moreover, the practicality of TRX was assessed in different types of berries, yielding satisfactory recoveries.

A Ce2MgMoO6 double perovskite decorated on a functionalized carbon nanofiber nanocomposite for quantification of ciprofloxacin in milk and honey samples: Density functional theory interpretation

In this study, a novel Ce2MgMoO6/CNFs (cerium magnesium molybdite double perovskite decorated on carbon nanofibers) nanocomposite was developed for selective and ultra-sensitive detection of ciprofloxacin (CFX). Physical characterization and analytical techniques were used to explore the morphology, structure, and electrocatalytic characteristics of the Ce2MgMoO6/CNFs nanocomposite. The sensor has a wide linear range (0.005-7.71 μM and 9.75-77.71 μM), a low limit of detection (0.012 μM), high sensitivity (0.807 μA μM-1 cm-2 nM), remarkable repeatability, and an appreciable storage stability. Here, we used density functional theory to investigate CFX and oxidized CFX as well as the locations of the energy levels and electron transfer sites. Furthermore, the Ce2MgMoO6/CNFs-modified electrode was successfully tested in food samples (milk and honey), indicating an acceptable response with a recovery percentage and relative standard deviation of less than 4%, which is comparable to that of GC-MS. Finally, the developed sensor exhibited high selectivity and stability for CFX detection.

COVID-19 Virus Structural Details: Optical and Electrochemical Detection

The increasing viral species have ruined people's health and the world's economy. Therefore, it is urgent to design bio-responsive materials to provide a vast platform for detecting a different family's passive or active virus. One can design a reactive functional unit for that moiety based on the particular bio-active moieties in viruses. Nanomaterials as optical and electrochemical biosensors have enabled better tools and devices to develop rapid virus detection. Various material science platforms are available for real-time monitoring and detecting COVID-19 and other viral loads. In this review, we discuss the recent advances of nanomaterials in developing the tools for optical and electrochemical sensing COVID-19. In addition, nanomaterials used to detect other human viruses have been studied, providing insights for developing COVID-19 sensing materials. The basic strategies for nanomaterials develop as virus sensors, fabrications, and detection performances are studied. Moreover, the new methods to enhance the virus sensing properties are discussed to provide a gateway for virus detection in variant forms. The study will provide systematic information and working of virus sensors. In addition, the deep discussion of structural properties and signal changes will offer a new gate for researchers to develop new virus sensors for clinical applications.

Voltammetric determination of tryptophan at graphitic carbon nitride modified carbon paste electrode

Herein, we reported carbon paste electrode modified with graphitic carbon nitride (g-C3N4-CPE) to determine of tryptophan (Trp) using voltametric techniques. Various spectroscopic and electrochemical techniques were used to characterize the as-synthesized g-C3N4 and the assembled electrodes. The transfer coefficient, rate constant and the diffusion coefficient of Trp in this system were found to be 0.28, 1.9 × 104 M-1s-1 and 3.2 × 10-5 cm2s-1, respectively. The linear range was obtained for the detection of Trp using LSV is from 0.1 μM to 120 μM at pH 5. The limit of detection (LOD) (3σ/m) was 0.085 μM. The demonstrated modified CPE was also effectively used for the detection of Trp in milk with percentage recovery of 98 %-105.2 %. Furthermore, the modified CPE exhibited good repeatability, reproducibility and appropriate selectivity.

A comparison of conventional and advanced electroanalytical methods to detect SARS-CoV-2 virus: A concise review

Respiratory viruses are a serious threat to human wellbeing that can cause pandemic disease. As a result, it is critical to identify virus in a timely, sensitive, and precise manner. The present novel coronavirus-2019 (COVID-19) disease outbreak has increased these concerns. The research of developing various methods for COVID-19 virus identification is one of the most rapidly growing research areas. This review article compares and addresses recent improvements in conventional and advanced electroanalytical approaches for detecting COVID-19 virus. The popular conventional methods such as polymerase chain reaction (PCR), loop mediated isothermal amplification (LAMP), serology test, and computed tomography (CT) scan with artificial intelligence require specialized equipment, hours of processing, and specially trained staff. Many researchers, on the other hand, focused on the invention and expansion of electrochemical and/or bio sensors to detect SARS-CoV-2, demonstrating that they could show a significant role in COVID-19 disease control. We attempted to meticulously summarize recent advancements, compare conventional and electroanalytical approaches, and ultimately discuss future prospective in the field. We hope that this review will be helpful to researchers who are interested in this interdisciplinary field and desire to develop more innovative virus detection methods.