Amperometric nitrite sensor based on a glassy carbon electrode modified with electrodeposited poly(3,4-ethylenedioxythiophene) doped with a polyacenic semiconductor

Electrochemical Sensor Based on Iron(II) Phthalocyanine and Gold Nanoparticles for Nitrite Detection in Meat Products

Nitrites are widely used in the food industry, particularly for the preservation of meat products. Controlling the nitrate content in food is an important task to ensure people's health is not at risk; therefore, the search for, and research of, new materials that will modify the electrodes in the electrochemical sensors that detect and control the nitrate content in food products is an urgent task. In this paper, we describe the electrochemical behavior of a glass carbon electrode (GCE), modified with a Fe(II) tetra-tert-butyl phthalocyanine film (FePc(tBu)₄/GCE), and decorated with gold nanoparticles (Au/FePc(tBu)₄/GCE); this electrode was deposited using gas-phase methods. The composition and morphology of such electrodes were examined using spectroscopy and electron microscopy methods, whereas the main electrochemical characteristics were determined using cyclic voltammetry (CV) and amperometry (CA) methods in the linear ranges of CV 0.25-2.5 mM, CA 2-120 μM in 0.1 M phosphate buffer (pH = 6.8). The results showed that the modification of bare GCEs, with a Au/FePc(tBu)₄ heterostructure, provided a high surface-to-volume ratio, thus ensuring its high sensitivity to nitrite ions of 0.46 μAμM^-1. The sensor based on the Au/FePc(tBu)₄/GCE has a low limit of nitrite detection at 0.35 μM, good repeatability, and stability. The interference study showed that the proposed Au/FePc(tBu)₄/GCE exhibited a selective response in the presence of interfering anions, and the analytical capability of the sensor was demonstrated by determining nitrite ions in real samples of meat products.

Sensitive analytical detection of nitrite using an electrochemical sensor with STAB-functionalized Nb2C@MWCNTs for signal amplification

An electrochemical sensor based on stearyl trimethyl ammonium bromide - functionalized niobium carbide@multi-walled carbon nanotubes (Nb₂C@MWCNTs-STAB) for signal amplification was successfully constructed for sensitive detection of nitrite (NO₂^-). Niobium carbide@multi-walled carbon nanotubes (Nb₂C@MWCNTs) with high electrical conductivity and water dispersibility were first prepared in a one-pot hydrothermal synthesis, after which cationic STAB was added to overcome the negative surface charge on the Nb₂C@MWCNTs. The electrostatic attraction between Nb₂C@MWCNTs-STAB and NO₂^- was improved by the STAB, which enhanced the sensitivity of the constructed sensor for NO₂^-. Under optimized conditions, Nb₂C@MWCNTs-STAB/GCE exhibited excellent analytical performance for detection NO₂^- with two wide liner ranges (0.1-100 μmol L^-1 and 100-2000 μmol L^-1) and a limit of detection of 0.022 μmol L^-1. Nitrite recovery tests in milk and spinach samples showed recoveries in the range of 89.82-104.52%. The NO₂^- residues in ham and pickled vegetable (cedrela sinensis) samples were analysed using the presented sensor and a spectrophotometric method, with no significant difference found between the results of the two methods.

MOF-assisted antifouling material: application in rapid determination of TB gene in whole-serum specimens

Biofouling is a nuisance in the practical applications of biosensors, which seriously affects the reliability and accuracy of detection. The utilization of antifouling interface materials is a promising option for mitigating biofouling. Only highly accumulated antifouling polymeric surfaces tend to offer "zero" nonspecific protein adsorption. Herein, superior antifouling coatings based on chondroitin sulfate (CS) were prepared by the NH₂-MIL-53 (Al) assisted strategy. This is a novel design to improve the antifouling property of material by taking advantage of the high specific surface area of the three-dimensional MOF to increase the accumulation degree of antifouling functional groups per unit area. And the related chemical technology is simple and easy to operate. As expected, this novel CS-loaded MOF demonstrated an excellent antifouling performance in various biological samples, even in 100% goat serum. Only 8.48% changes of differential pulse voltammetry (DPV) were found. Furthermore, this antifouling interface material is successfully applied for the specific detection of the tuberculosis (TB) gene in undiluted biofluids. This developed TB biosensor showed a high analytical performance with a wide linear range (1.00 × 10^-16 M to 1.00 × 10^-11 M) and a low detection limit, indicating that it may open new avenues for direct biosensing of disease markers for clinical samples.

Mesoporous Carbon/α-Fe2O3 Nanoleaf Composites for Disposable Nitrite Sensors and Energy Storage Applications

In this work, we report a novel hydrothermal synthesis of α-Fe₂O₃ nanoleaf-incorporated mesoporous carbon-chitosan (α-Fe₂O₃@MPC-chit) as a versatile disposable sensor for selective electrochemical detection of nitrite and for supercapacitor applications. The newly synthesized α-Fe₂O₃@MPC-chit nanocomposite was characterized by scanning electron microscopy, X-ray diffraction, Fourier transform-infrared spectroscopy, UV, and Raman spectroscopy. The extensive physicochemical characterization reveals the strong immobilization of α-Fe₂O₃ nanoleaves within the MPC-chit composite. The electrochemical characterization with cyclic voltammetry and impedance spectroscopy using [Fe(CN)₆)]^3-/4- as a redox probe concludes good electron conductivity and efficient electron transfer behavior of α-Fe₂O₃@MPC-chit. The α-Fe₂O₃@MPC-chit modified electrode exhibits excellent electrocatalytic activity toward nitrite oxidation. The amperometric method of nitrite detection showed a linear range of up to 200 μmol L^-1 _. The current sensitivity and detection limit were found to be 0.913 μA μM^-1 and 31 nM cm^-2, respectively. The improved catalytic activity of the proposed electrode was endorsed by the synergistic effect of α-Fe₂O₃ with the MPC-chit composite. The ability of the proposed electrode was demonstrated by the successful detection of nitrite present in tap water, river water, and industrial samples with extensive recovery values. Furthermore, the α-Fe₂O₃@MPC-chit modified stainless-steel electrode showed high-performance supercapacitor application and exhibited a large specific capacitance of 380 F g^-1 at 1 A g^-1.

A screen printed carbon electrode modified with a lamellar nanocomposite containing dendritic silver nanostructures, reduced graphene oxide, and β-cyclodextrin for voltammetric sensing of nitrite

A disposable sensor is described for the determination of nitrite. A screen printed carbon electrode (SPCE) was modified with a 3D lamellar nanocomposite prepared by one-step electrodeposition from dendritic silver nanostructures, reduced graphene oxide, and β-cyclodextrin. The modified SPCE exhibits high electrocatalytic activity toward nitrite oxidation, typically at a working potential at around 0.76 V (vs. Ag/AgCl). Sensitive and selective voltammetric detection of nitrite is demonstrated. The linear range extends from 1 to 2000 μM, the detection limit is 0.24 μM, and the sensitivity is 585.7 μA mM-1 cm-2. The method was applied to the determination of nitrite in (spiked) pickles. Graphical abstract Schematic presentation of fabrication of a screen printed carbon electrode modified with a lamellar nanocomposite containing dendritic silver nanostructures, reduced graphene oxide, and β-cyclodextrin. Graphical abstract contains poor quality of text inside the artwork. Please do not re-use the file that we have rejected or attempt to increase its resolution and re-save. It is originally poor, therefore, increasing the resolution will not solve the quality problem. We suggest that you provide us the original format. We prefer replacement figures containing vector/editable objects rather than embedded images. Preferred file formats are eps, ai, tiff and pdf.We have provided the original format of graphical abstract in the attachment.

Functionalized Carbon Materials for Electronic Devices: A Review

Carbon-based materials, including graphene, single walled carbon nanotubes (SWCNTs), and multi walled carbon nanotubes (MWCNTs), are very promising materials for developing future-generation electronic devices. Their efficient physical, chemical, and electrical properties, such as high conductivity, efficient thermal and electrochemical stability, and high specific surface area, enable them to fulfill the requirements of modern electronic industries. In this review article, we discuss the synthetic methods of different functionalized carbon materials based on graphene oxide (GO), SWCNTs, MWCNTs, carbon fibers (CFs), and activated carbon (AC). Furthermore, we highlight the recent developments and applications of functionalized carbon materials in energy storage devices (supercapacitors), inkjet printing appliances, self-powered automatic sensing devices (biosensors, gas sensors, pressure sensors), and stretchable/flexible wearable electronic devices.

Ultrasensitive Electrochemical Sensor Based on Polyelectrolyte Composite Film Decorated Glassy Carbon Electrode for Detection of Nitrite in Curing Food at Sub-Micromolar Level

To ensure food quality and safety, developing cost-effective, rapid and precision analytical techniques for quantitative detection of nitrite is highly desirable. Herein, a novel electrochemical sensor based on the sodium cellulose sulfate/poly (dimethyl diallyl ammonium chloride) (NaCS/PDMDAAC) composite film modified glass carbon electrode (NaCS/PDMDAAC/GCE) was proposed toward the detection of nitrite at sub-micromolar level, aiming to make full use of the inherent properties of individual component (biocompatible, low cost, good electrical conductivity for PDMDAAC; non-toxic, abundant raw materials, good film forming ability for NaCS) and synergistic enhancement effect. The NaCS/PDMDAAC/GCE was fabricated by a simple drop-casting method. Electrochemical behaviors of nitrite at NaCS/PDMDAAC/GCE were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Under optimum conditions, the NaCS/PDMDAAC/GCE exhibits a wide linear response region of 4.0 × 10⁻⁸ mol·L⁻¹~1.5 × 10⁻⁴ mol·L⁻¹ and a low detection 1imit of 43 nmol·L⁻¹. The NaCS/PDMDAAC shows a synergetic enhancement effect toward the oxidation of nitrite, and the sensing performance is much better than the previous reports. Moreover, the NaCS/PDMDAAC also shows good stability and reproducibility. The NaCS/PDMDAAC/GCE was successfully applied to the determination of nitrite in ham sausage with satisfactory results.