Low potential detection of antiprotozoal drug metronidazole with aid of novel dysprosium vanadate incorporated oxidized carbon nanofiber modified disposable screen-printed electrode

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.

Binary metal oxide (NiO/SnO2) composite with electrochemical bifunction: Detection of neuro transmitting drug and catalysis for hydrogen evolution reaction

The synergetic effect between dual oxides in binary metal oxides (BMO) makes them promising electrode materials for the detection of toxic chemicals, and biological compounds. In addition, the interaction between the cations and anions of diverse metals in BMO tends to create more oxygen vacancies which are beneficial for energy storage devices. However, specifically targeted synthesis of BMO is still arduous. In this work, we prepared a nickel oxide/tin oxide composite (NiO/SnO2) through a simple solvothermal technique. The crystallinity, specific surface area, and morphology were fully characterized. The synthesized BMO is used as a bifunctional electrocatalyst for the electrochemical detection of dopamine (DPA) and for the hydrogen evolution reaction (HER). As expected, the active metals in the NiO/SnO2 composite afforded a higher redox current at a reduced redox potential with a nanomolar level detection limit (4 nm) and excellent selectivity. Moreover, a better recovery rate is achieved in the real-time detection of DPA in human urine and DPA injection solution. Compared to other metal oxides, NiO/SnO2 composite afforded lower overpotential (157 mV @10 mA cm-2), Tafel slope (155 mV dec-1), and long-term durability, with a minimum retention rate. These studies conclude that NiO/SnO2 composite can act as a suitable electrode modifier for electrochemical sensing and the HER.

Sense and Shoot: Unveiling the Electro-/Photocatalytic Potential of 2D White Graphene-Supported Perovskite Strontium Cobaltite from Detection to Remediation of Oxidative Stress Herbicide (Mesotrione)

In this research, we employed a strategy akin to "Feeding Two Birds with One Stone" aiming for the dual objectives of highly selective electrochemical detection and photocatalytic degradation of the environmentally hazardous herbicide mesotrione (MTN). We achieved this by utilizing hexagonal boron nitride (BN)-supported strontium cobaltite perovskite nanocomposites (SrCoO3/BN). The fabrication of the innovative bifunctional SrCoO3/BN nanocomposites involved a straightforward process of precipitation, followed by an annealing treatment and ultrasonication. The successful formation of these nanocomposites was corroborated through the application of diverse spectroscopic tools. Notably, as-prepared SrCoO3/BN nanocomposites exhibited a remarkable sensing platform for MTN, characterized by a notably low detection limit (11 nm), considerable sensitivity (3.782 μA μM-1 cm-2), and outstanding selectivity, alongside remarkable stability. Concurrently, these SrCoO3/BN nanocomposites demonstrated exceptional visible-light-driven photocatalytic efficacy for MTN degradation (99%) and complete mineralization. Our investigation systematically delved into the influence of operational parameters, including catalyst loading and the involvement of reactive oxidative species, in both the electrocatalytic and photocatalytic reactions. Drawing from these comprehensive studies, we have proposed plausible mechanisms for detecting and degrading MTN. Our findings pave the way for catalyst development, offering a unified solution for detecting and eliminating toxic organic compounds from the environment.

Ingenious fabrication of bamboo leaf-like ferric vanadate intertwined multi-walled carbon nanotubes nanocomposite as a sensitive sensor for determination of uric acid in fetal bovine serum

A novel nanocomposite material, ferric vanadate intertwined multi-walled carbon nanotubes (FeV/MWCNTs), has been designed which was drop-coated onto a glassy carbon electrode (GCE). The constructed sensor was used for the sensitive determination of uric acid (UA) in fetal bovine serum (FBS) and human serum (HS). A series of characterization and electrochemical tests showed that the ultrasound-assisted assembly of FeV with MWCNTs not only overcame the disadvantages of low conductivity and easy (unwanted) aggregation, but also avoided the decrease in effective surface area due to the severe aggregation of each individual raw material. The fabricated FeV/MWCNTs nanocomposites exhibited higher conductivity, larger effective surface area, and better electrocatalytic activity. In addition, under optimized conditions, the developed electrochemical sensor FeV/MWCNTs/GCE has a lower limit of detection (LOD, 0.05 µM; Ep = 0.268 V vs. Ag/AgCl) and wider linear range (0.20-100 µM), which can satisfy the criteria of trace UA detection. The results of UA determination in FBS (recovery = 95.5-103%; RSD ≤ 3.1%) and HS (recovery = 95.5-103%; RSD ≤ 4.3%) further validated the feasibility of FeV/MWCNTs-based electrochemical sensors for the determination of UA in biological fluids.

Efficient detection of metronidazole by a glassy carbon electrode modified with a composite of a cyclotriveratrylene-based metal-organic framework and multi-walled carbon nanotubes

Constructing a sensitive and efficient sensor for determination of metronidazole (MNZ) is crucial in food field. Herein, a new cyclotriveratrylene-based metal-organic framework (MOF), namely, [Cd₆L₂(cyclen)₂(H₂O)₂] (1), was constructed by self-assembly of functionalized 5,6,12,13,19,20-hexacarboxy-propoxy-cyclotriveratrylene (H₆L), 1,4,7,10-tetraazacyclododecane (cyclen) and Cd(II) cation under solvothermal condition. In 1, adjacent Cd(II) cations are linked by L^6- to produce a 2D polymeric structure with carboxylate and phenolic oxygen atoms. To enhance conductivity of 1, it was combined with conducting carbon materials, including mesoporous carbon (MC), reduced graphene oxide (RGO) and multi-walled carbon nanotubes (MWCNT), respectively, producing a series of composite materials. Remarkably, electrochemical tests showed that 1@MWCNT(1:1) featured a much better electrochemical detection performance for metronidazole (MNZ) than 1@MC and 1@RGO. The linear range for the detection of MNZ is up to 0.4-500 μM and the limit of detection (LOD) for MNZ reached 0.25 μM. Importantly, the fabricated sensor 1@MWCNT(1:1) was employed for the detection of MNZ in honey and egg with satisfactory result. High-performance liquid chromatography (HPLC) validated the high accuracy of the electrochemical method for the determination of honey and egg.

A novel sensing platform for electrochemical detection of metronidazole antibiotic based on green-synthesized magnetic Fe3O4 nanoparticles

The spread of antibiotic resistant genes has become a serious global concern. Thus, the development of efficient antibiotic monitoring systems to reduce their environmental risks is of great importance. Here, a potent electrochemical sensor was fabricated to detect metronidazole (MNZ) on the basis of green synthesis of Fe₃O₄ nanoparticles (NPs) using Sambucus ebulus L. leaves alcoholic plant extract as a safe and impressive reducing and stabilizing agent. Several analyses such as X-ray diffraction (XRD), Fourier transform infrared spectrophotometer (FTIR), thermogravimetric analysis (TGA), field emission scanning electron microscope (FESEM), energy dispersive X-ray spectroscopy (EDX), and dynamic light scattering (DLS) confirmed the production of homogeneous, monodisperse, regular, and stable magnetite NPs with a spherical morphology. The as-prepared Fe₃O₄NPs were afterwards applied to evaluate the electrochemical activity of MNZ by merging them with graphene nanosheets (GR NSs) on the glassy carbon electrode (GCE). The GR/Fe₃O₄NPs/GCE represented extraordinary catalytic activity toward MNZ with two dynamic ranges of 0.05-5 μM and 5-120 μM, limit of detection (LOD) of 0.23 nM, limit of quantification (LOQ) of 0.76 nM, and sensitivity of 7.34 μA μM^-1 cm^-2. The fabricated sensor was further employed as a practical tool for electrochemical detection of MNZ in real aqueous samples.

Study on Metronidazole Acid-Base Behavior and Speciation with Ca2+ for Potential Applications in Natural Waters

Metronidazole (MNZ) is an antibiotic widely used for the treatment of various infectious diseases and as an effective pesticide agent for the cultivation of chickens and fish. Its high resistance to purification processes and biological activity has led to the classification of MNZ as an emerging contaminant. A speciation study, aimed to define the acid-base properties of MNZ and its interaction with Ca²⁺, commonly present in natural waters, is reported. The protonation constants of MNZ, as well as the formation constant value of Ca²⁺-MNZ species, were obtained by potentiometric titrations in an aqueous solution, using NaCl as background salt at different ionic strengths (0.15, 0.5, 1 mol L⁻¹) and temperature (15, 25 and 37 °C) conditions. The acid-base behavior and the complexation with Ca²⁺ were also investigated by ¹H NMR and UV-Vis titrations, with results in very good agreement with the potentiometric ones. The dependence of the formation constants on the ionic strength and temperature was also determined. The sequestering ability of MNZ towards Ca²⁺ was defined by the empirical parameter pL_0.5 at different pH and temperature values. The speciation of MNZ simulating sea water conditions was calculated.

A simple and green method to prepare non-typical yolk/shell nanoreactor with dual-shells and multiple-cores: Enhanced catalytic activity and stability in Fenton-like reaction

Nowadays, non-typical yolk/shell structure has drawn much attentions due to the better catalytic performance than traditional counterparts (one yolk/one shell). In this study, ZIF-67 @Co₂SiO₄/SiO₂ yolk/shell structure was prepared in one-step at room temperature, in which ZIF-67 was served as the hard-template, H₂O was served as etchant and tetraethyl orthosilicat was served as the raw material for Co₂SiO₄/SiO₂. After calcination, the non-typical Co_xO_y @Co₂SiO₄/SiO₂ yolk/shell nanoreactor with Co₂SiO₄/SiO₂ dual-shells and Co_xO_y multiple-cores was obtained. On the one hand, more active sites were exposed on multiple-cores surface and better protection were provided by dual-shells. On the other hand, the sheet-like Co₂SiO₄ inner shell not only extended the travel path and retention time of pollutants trapped in cavity, but also separated the multiple-cores from aggregation. Therefore, the nanoreactor displayed the outstanding catalytic activity and recyclability in Fenton-like reaction. Metronidazole (20 mg/L) was completely degraded after 30 min, rhodamine B (50 mg/L) and methyl orange (20 mg/L) were removed even within 5.0 min. Catalytic mechanism indicated that ¹O₂ greatly contributed to the pollutant degradation. This paper presented a simple, versatile, green and energy-saving method for non-typical yolk/shell nanoreactor, and it could inspire to prepare other catalysts with high activity and stability for environmental remediation.

Advances of Drugs Electroanalysis Based on Direct Electrochemical Redox on Electrodes: A Review

The strong development of mankind is inseparable from the proper use of drugs, and the electroanalytical research of drugs occupies an important position in the field of analytical chemistry. This review mainly elaborates the research progress of drugs electroanalysis based on direct electrochemical redox on various electrodes for the recent decade from 2011 to 2021. At first, we summarize some frequently used electrochemical data processing and electrochemical mechanism research derivation methods in the literature. Then, according to the drug therapeutic and application/usage purposes, the research progress of drugs electrochemical analysis is classified and discussed, where we focus on drugs electrochemical reaction mechanism. At the same time, the comparisons of electrochemical sensing performance of the drugs on various electrodes from recent studies are listed, so that readers can more intuitively compare and understand the electroanalytical sensing performance of each modified electrode for each of the drug. Finally, this review discusses the shortcomings and prospects of the drugs electroanalysis based on direct electrochemical redox research.

Insights into the Design and Electrocatalytic Activity of Magnesium Aluminum Layered Double Hydroxides: Application to Nonenzymatic Catechol Sensor

The design of an efficient electrocatalyst for effective trace level determinations of noxious synthetic and or biological compounds is the unceasingly noteworthy conceptual approach for rapid technology. In this work, we designed a magnesium-aluminum layered double hydroxides (Mg-Al LDHs) nanocatalyst and applied it to the electrocatalytic determination of an extremely carcinogenic catechol sensor. A coprecipitation method was employed for synthesizing the nanocatalyst, and the structure, porous nature, and morphology were confirmed by X-ray diffraction, Fourier transform infrared spectroscopy, N₂ adsorption-desorption isotherm, field emission-scanning electron microscopy, and transmission electron microscopy. The elemental composition was observed by energy dispersive X-ray analysis. The electrochemical studies were investigated with the help of cyclic voltammetry and differential pulse voltammetry techniques. The Mg-Al LDHs-based electrocatalyst was used to detect catechol by electrochemical measurements with different parameters. The proposed catechol sensor shows a wide dynamic range (0.007-200 μM) with a lower level of detection (2.3 nm) and sensitivity (3.57 μA μM^-1 cm^-2). The excellent sensor performance is attributed to the high surface area, fast electron transfer, more active sites, and excellent flexibility. This study depicts the proposed sensor as probable to practical in a scientific investigation. In addition, the modified electrode showed greater selectivity and was used in the detection of fatal contaminants in instant treatment strategies. Moreover, the Mg-Al LDHs confirmed auspicious real sample scrutiny with noteworthy retrieval outcomes in lake water samples which exposed improved consequences.

Barium titanate nanoparticle-based disposable sensor for nanomolar level detection of the haematotoxic pollutant quinol in aquatic systems

Barium titanate nanoparticles synthesized by a simple co-precipitation method and applied for the electrochemical detection of quinol.

Enhanced effect of pyrite on the removal of metronidazole by zero valent iron

The abuse and improper disposal of antibiotics including metronidazole (MNZ) result in serious contamination in aquatic environments. In this study, pyrite, which was not reactive for MNZ removal, was simply mixed with zero valent iron (ZVI) to efficiently remove MNZ in anaerobic aqueous solutions. A dual ZVI/pyrite system consisting of ZVI (1.0 g/L) and pyrite (4.0 g/L) removed MNZ completely in 360 min within a broad pH₀ range (5.0-9.0), and it still maintained a high removal efficiency (~80%) even at a high pH₀ of 10.0. By contrast, single ZVI (1.0 g/L) showed much lower efficiency (4.8%-22.0%) within the same pH₀ range (5.0-10.0). On investigating the mechanism of MNZ removal, the cooperation between ZVI and pyrite enhanced the surface corrosion of ZVI and facilitated the redox cycle of Fe(III)/Fe(II) to generate more sorbed Fe(II), which was a dominant reactive species for MNZ removal. Pyrite also activated the ZVI surface to form FeS@Fe in situ, accelerating the electron transfer from Fe⁰ core to the surface-enriched MNZ, and stimulated the formation of green rust sulfate on the ZVI surface to further promote MNZ removal. LC-MS analysis confirmed ZVI/pyrite reductively transformed MNZ into readily biodegradable products by denitration and cleavage of hydroxyethyl.

Toward the Development of Disposable Electrodes Based on Holmium Orthovanadate/f-Boron Nitride: Impacts and Electrochemical Performances of Emerging Inorganic Contaminants

Rare-earth metal orthovanadates have great technological relevance in the family of rare-earth compounds owing to their excellent physical and chemical properties. A significant number of studies have been carried out on this class of compounds to exploit their electrochemical properties in virtue of variable oxidation states. But holmium vanadate (HoV) and its morphology selective synthesis have not been considered, which can have potential applications similar to the rest of the family. In this work, we propose the synthesis of superior architectures of HoV with a functionalized boron nitride (f-BN) nanocomposite. The synergistic effect between HoV and f-BN can have a positive effect on the physical characteristics of the nanocomposite, which can be explored for its electrochemical capacity. Here, HoV incorporated with f-BN is explored for the electrochemical detection of Hg²⁺ ions, which is known for its toxicity-induced environmental health hazards. The structural and compositional revelation reveals higher conductivity and faster electron transfer in the composite, which facilitates a wide working range (0.02-53.8 and 64.73-295.4 μM), low limit of detection (5 nM), higher sensitivity (66.6 μA μM^-1 cm^-2), good selectivity over 10-fold higher concentration of other interfering compounds compared to Hg²⁺ ion concentration, and good cycles stability (30 segments) toward Hg²⁺ ion detection. This also envisages the morphology selective synthesis and utilization of other rare-earth metals, whose electrochemical capacities are unexplored.

Sustainable one-pot synthesis of strontium phosphate nanoparticles with effective charge carriers for the photocatalytic degradation of carcinogenic naphthylamine derivative

In this work, a sustainable one-pot precipitation method was applied for synthesizing strontium phosphate nanoparticles (SrPO NPs), which can be utilized as effective charge separation photocatalysts for the degradation of oncogenic naphthylamine derivatives (congo red).