Modification of glassy carbon electrode with manganese cobalt oxide-cubic like structures incorporated graphitic carbon nitride sheets for the voltammetric determination of 2,4,6 -trichlorophenol

Novel cube-like transition metal oxide embedded on graphitic carbon nitride (MCO@GCN) formed a hybrid composite via hydrothermal assisted sonochemical synthesis. The synthesized composite was examined with various physical characterizations such as morphological SEM, EDX, XRD, and FT-IR spectroscopy. The electrocatalytic activity of MCO@GCN composite was further investigated when used  to modify a glassy carbon electrode (GCE). The electrochemical sensor was investigated using modified MCO@GCN/GCE towards environmental pollutant 2,4,6-trichlorophenol (2,4,6-TCP) detection with at a potential of (+ 0.654 V vs Ag/AgCl) in pH-7. The structural features have favored a high charge transfer ratio with excellent conductivity which showed a low detection limit (LOD) of 0.0068 μM and sensitivity of 23.57 μA·μM^-1·cm^-2 comprising a wide linear working range of 0.01-1720 μM by using differential pulse voltammetry. Besides, the MCO@GCN/GCE displayed excellent selectivity , repeatability, reproducibility, storage, and operational stability. Notably, the proposed MCO@GCN/GCE was validated with different environmental samples (tap, river, and industrial water) with RSD 0.62-2.86% and 96.51-99.66% (n = 3) recovery.

Human sweat-based wearable glucose sensor on cotton fabric for real-time monitoring

In this work, a human sweat-based wearable sensor for real-time glucose monitoring has been fabricated on a cotton substrate after treating it with a two-step polymerization of pyrrole. The pyrrole-treated fabric was coated with solution of copper sulphate pentahydrate to grow Cu layer. The cotton/pyrrole/Cu fabric was treated with the solutions of copper acetate and manganese acetate to form Cu–Mn transition-metal alloy via electrochemical deposition technique. Results indicate that the developed sensor is reliable with glucose detection limit of 125 µM and 378 µM. In addition, the sensor output ranged between 50 and 400 µM glucose with coefficient of correlation, R2 = 0.983, indicating a linear range of output current. The sensor's response is not significantly affected by interferents. The developed sensor is also validated on human sweat with satisfactory results.

Improving sensitivity of antimicrobial drug nitrofurazone detection in food and biological samples based on nanostructured anatase-titania sheathed reduced graphene oxide

In this study, we have prepared anatase titanium (IV) oxide warped reduced graphene oxide nanocomposites (TiO₂-rGO NC) using ultrasonic methodology. The morphology of the TiO₂-rGO NC was studied using FESEM and TEM. In addition, XRD, Raman, thermogravimetric analysis (TGA) and XPS are used to analyze the crystallinity and chemical composition of the TiO₂-rGO NC. We have also investigated the electrochemical behavior of the as-prepared NCs with electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and different pulse voltammetry techniques (DPV). The TiO₂-rGO NC modified electrode shows the lower charge transfer resistance (R _ct ) of 62.87 Ω. Next, the glassy carbon electrode (GCE) was modified with sonochemically prepared TiO₂-rGO NC and used to determine the electrocatalytic reduction of nitrofurazone (NTF). Thus, the proposed sensor established the wider covering range (WCR) of 0.01 to 380 µM and an excellent detection limit of 2.28 nM. Finally, the TiO₂-rGO NC/GCE was applied to determine the NTF in real samples, including crayfish and human blood serum samples, which acquired good found and recovery values.

Non-enzymatic sensor for determination of glucose based on PtNi nanoparticles decorated graphene

Diabetes has become a universal epidemic in recent years. Herein, the monitoring of glucose in blood is of importance in clinical applications. In this work, PtNi alloy nanoparticles homogeneously dispersed on graphene (PtNi alloy-graphene) was synthesized as a highly effective electrode material for glucose detection. Based on the modified PtNi alloy-graphene/glass carbon (PtNi alloy-graphene/GC) electrode, it is found that the PtNi alloy-graphene/GC electrode exhibited excellent electrocatalytic performance on glucose oxidation. Furthermore, the results from amperometric current–time curve show a good linear range of 0.5–15 mM with the limit of detection of 16 uM (S/N = 3) and a high sensitivity of 24.03 uAmM⁻¹ cm⁻². On account of the good selectivity and durability, the modified electrode was successfully applied on glucose detection in blood serum samples.

A sonochemical assisted synthesis of hollow sphere structured tin (IV) oxide on graphene oxide sheets for the low-level detection of environmental pollutant mercury in biological samples and foodstuffs

In modern approaches for nanomaterials synthesis, ultrasonication plays an important role in providing the larger surface area and smaller crystalline size properties that are favorable to electrochemical techniques. Herein, we report the tin (IV) oxide on graphene oxide nanoparticles were synthesized (SnO₂@GO NPs) by ultrasonic methodology (UZ SONOPULS HD 3400 Ultrasonic homogenizer) with the total power of 400 W and the (frequency of 20 kHz; 140 W/dm³). The formation of as-prepared SnO₂@GO NPs and its surface morphology were scrutinized over XRD, XPS, TEM, and FESEM. Besides, the sonochemically prepared SnO₂@GO NPs were employed for the determination of environmental hazardous mercury (Hg). As a result, the modified electrode acquired a very low-level detection limit of 1.2 nM with a wider range of 0.01-10.41-µM and 14.52-225.4-µM for the detection of Hg. Finally, the practical applicability of SnO₂@GO NPs in spiked human blood serum and tuna fish samples shows appreciable found and recovery values. .

An Ultra-Sensitive Electrochemical Sensor for the Detection of Carcinogen Oxidative Stress 4-Nitroquinoline N-Oxide in Biologic Matrices Based on Hierarchical Spinel Structured NiCo2O4 and NiCo2S4; A Comparative Study

Various factors leads to cancer; among them oxidative damage is believed to play an important role. Moreover, it is important to identify a method to detect the oxidative damage. Recently, electrochemical sensors have been considered as the one of the most important techniques to detect DNA damage, owing to its rapid detection. However, electrode materials play an important role in the properties of electrochemical sensor. Currently, researchers have aimed to develop novel electrode materials for low-level detection of biomarkers. Herein, we report the facile hydrothermal synthesis of NiCo₂O₄ micro flowers (MFs) and NiCo₂S₄ micro spheres (Ms) and evaluate their electrochemical properties for the detection of carcinogen-causing biomarker 4-nitroquinoline n-oxide (4-NQO) in human blood serum and saliva samples. Moreover, as-prepared composites were fabricated on a glass carbon electrode (GCE), and its electrochemical activities for the determination of 4-NQO were investigated by using various electrochemical techniques. Fascinatingly, the NiCo₂S₄-Ms showed a very low detection limit of 2.29 nM and a wider range of 0.005 to 596.64 µM for detecting 4-NQO. Finally, the practical applicability of NiCo₂S₄-Ms in the 4-NQO spiked human blood serum and saliva samples were also investigated.