Engineered tenorite structure of barium-enriched copper oxide for on-site monitoring of cytotoxic methotrexate in environmental samples.

Emerging pharmaceutical pollutants pose a threat to both human and environmental health. The removal and monitoring of such pollutants necessitate the use of practical on-site monitoring devices; however, the designs of such devices are underdeveloped. This study involves the fabrication of a low-cost sensor based on barium-incorporated copper oxide (Ba-CuO) for the on-site monitoring of the cytotoxic drug methotrexate (MTRX) in water and sediment samples. The tenorite structure of CuO was slightly enriched with Ba ions at the td sites, distorting the tetrahedron and enhancing its electrochemical properties. Ba-CuO was obtained from Cu(NO3)2 and Ba(OH)2 by a ligand exchange protocol and was characterized using X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray analysis. In addition, the Ba-CuO sensor was tested under various conditions, and it could detect MTRX at concentrations as low as 0.4 nM, with a high sensitivity of 1.3567 µA µM-1 cm-2. On-site monitoring yielded recoveries of greater than 93 % from spiked samples, thus exhibiting excellent reproducibility and stability. Therefore, the developed method is practical and has no matrix effect on the MTRX sensor.

Ultrasensitive detection of ineradicable and harmful antibiotic chloramphenicol residue in soil, water, and food samples.

Chloramphenicol (CAP) is a harmful antibiotic that inevitably enters our food chain through natural or manmade means. Its ineradicable residue pollutes soils and water, accumulates in plants and animal products, and eventually affects human health. An ultrasensitive method for detecting and monitoring CAP is therefore urgently required. Herein, we report an ultrafast extraction and amperometry detection method based on a graphite-sulfate-modified electrode for detecting CAP in soil, water, and food samples. The graphite sulfate is prepared by the oxidation method and its structural properties are comprehensively investigated. The developed sensor electrode showed a wider linear range of 0.3-32.0 µg kg-1 and an ultralow detection limit of 0.1 µg kg-1, both of which meet the European Commission Reg 1871/2019 reference points for action. The method works well with both meat and plant samples, achieving CAP recoveries ranging from 90.8 to 99.1% even at low concentrations. Moreover, the sensor electrode shows more than 95% selectivity toward CAP detection in the soil, water, and food matrices. The developed method exhibits good repeatability and reproducibility in the analysis of real samples.

Lanthanum tin oxide-modified sensor electrode for the rapid detection of environmentally hazardous insecticide carbaryl in soil, water, and vegetable samples.

The growing population and global food demands have encouraged the use of pesticides to increase agricultural yields; however, the irrational use of pesticides threatens human health and the environment. Carbaryl (CRBL) is the most widespread insecticide and severely affects soil, water systems, and human health. Thus, it is crucial to monitor CRBL residues in the environment and vegetable samples. This study reports the rapid and sensitive electrochemical detection of CRBL based on a pyrochlore-type lanthanum tin oxide (LSO) nanoparticles (NPs)-modified screen-printed carbon electrode (SPCE). A low-temperature hydrothermal method was employed to prepare the LSO NPs. The structural properties of the LSO NPs were characterized by X-ray diffraction, Raman, and X-ray photoelectron spectroscopy analyses. The LSO NPs/SPCE demonstrated good electroanalytical performance for CRBL detection, with a low detection limit of 0.4 nM (0.08 µg/L) and a sensitivity of 1.05 µA/(µM cm2). Furthermore, the LSO NPs/SPCE exhibited high selectivity among highly interfering carbamate and organophosphorus pesticides, which share similar mechanisms of action. Additionally, the LSO NPs/SPCE sensor achieved > 90% recovery for the detection of CRBL in soil, water, and vegetable samples, thus verifying its suitability for the rapid detection of CRBL.

Effect of the Ni3TeO6 phase in a Ni2Te3O8/expanded graphite composite on the electrochemical monitoring of metribuzin residue in soil and water samples.

Growing food demand and climate change have led to the development of various pest control agents to increase crop yields. Although pesticides help meet the food demand, they cause harm to human health and the environment. Metribuzin (MTBZ) is one of the common herbicides used for controlling weeds. Therefore, monitoring MTBZ residues in soil and water bodies is essential for decreasing risk to the environment and human health. This paper reports a highly selective and sensitive electrochemical sensor electrode based on a Ni3TeO6-phase-integrated Ni2Te3O8/expanded graphite (referred to here as NTO-eGR) composite for the detection of MTBZ. The NTO-eGR composite was prepared by a one-step low-temperature hydrothermal method and characterized by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and electron microscopy techniques. The Ni3TeO6 phase was found to be an active component in the NTO/eGR composite, which exhibited satisfactory analytical performance in MTBZ detection with a sensitivity of 1.454 µA µM-1 cm-2. Moreover, the NTO-eGR electrode exhibited high selectivity to MTBZ even in the presence of a five-fold excess of interfering species in water and soil samples. The studies on practical applicability revealed that NTO-eGR exhibits good reproducibility with a relative standard deviation of 2.67% (n = 5). Moreover, good recoveries of greater than 90% were achieved in the determination of MTBZ in soil and water samples. Hence, the NTO-eGR sensor electrode is highly suitable for the rapid on-site determination of MTBZ.

Synthesis and characterizations of iron antimony oxide nanoparticles and its applications in electrochemical detection of carbendazim in apple juice and paddy water samples.

This study reports a facile sonohydrolysis synthesis route to prepare the iron antimony oxide (FeSbO4) nanoparticles for the trace level electrochemical sensing of fungicide carbendazim (CRBZ). As prepared FeSbO4 nanoparticles show a nano-cubes-like morphology with uniform distributions that crystallized in the tetragonal phase. The diffraction studies reveal that the FeSbO4 nanoparticles have high crystallinity and high purity. Furthermore, the other structural properties and morphology are characterized by XRD, Raman, XPS, HRTEM, and FESEM analysis. The electrochemical characterizations of FeSbO4 modified GCE towards the detection of CRBZ are performed by cyclic voltammetry and chronoamperometry techniques. The FeSbO4/GCE exhibits a linear range from 0.01 µmol L-1 to 64.3 µmol L-1, the sensitivity of 0.68 µA cm-2 µM-1, and the LOD of 5.4 nmol L-1. Moreover, the FeSbO4/GCE delivered high selectivity among the possibly interfering compounds. Also, our projected FeSbO4/GCE electrode material shows good recoveries in apple juice and paddy water real samples.

Facile synthesis of single-crystalline Fe-doped copper vanadate nanoparticles for the voltammetric monitoring of lethal hazardous fungicide carbendazim.

The highly selective and sensitive electrochemical detection of highly toxic fungicide carbendazim (CBZ) by the iron (Fe)-doped copper vanadate (CuVO4; CuV) is discussed. The Fe-doped copper vanadate (Fe-CuV) is prepared by the simple co-precipitation method followed by an annealing process which produced high crystallinity. The material properties of Fe-CuV are characterized by XRD, Raman spectrometry, XPS analysis, HRTEM, and SAED pattern. The electrochemical characterization of Fe-CuV towards CBZ detection are done by CV and DPV techniques. The Fe-CuV/GCE exhibits good electroanalytical activity towards the electro-oxidation of CBZ at the potential of 0.81 V vs Ag/AgCl. The developed sensor electrode revealed a linear range of 0.01 to 83.1 µM and a limit of detection of about 5 nM. In addition, Fe-CuV/GCE reveals good storage stability (RSD = 2.63%) and reproducibility (RSD = 2.85%) for the electro-oxidation of CBZ. The electrode material was applied to the detection of CBZ in apple juice and soy milk samples, and the results were discussed. Thus, our projected Fe-CuV/GCE can be employed as electrode material in a rapid onsite sensor for the detection and determination of noxious pollutants.

Preparation of K+ intercalated MnO2-rGO composite for the electrochemical detection of nitroaniline in industrial wastewater.

This work reports the electrochemical detection of highly hazardous material 4-Nitroaniline (4-NA) based on the metal oxide-rGO composite materials. The potassium intercalated MnO2-rGO composite material was prepared by a simple one-pot reduction method. The K+ intercalation on K-MnO2-rGO was confirmed by X-ray photoelectron spectroscopy (XPS) and Raman analysis. The amorphous nature of prepared material was scrutinized by high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) pattern analysis. The elemental compositions are done by energy dispersive X-ray Analysis (EDX) mapping. The prepared composite material K-MnO2-rGO was used to determine the 4-NA by differential pulse voltammetry (DPV). The electroanalytical performances of fabricated K-MnO2-rGO/SPCE were compared with the K-MnO2 and rGO in pH 7. The developed 4-NA sensor showed good sensitivity (2.85 µA µM-1 cm-2), linear range (0.001-10.53 µM), and LOD (0.7 nM). Furthermore, the K-MnO2-rGO/SPCE exhibited high selectivity with the other potential interfering nitro compounds in river water and pond water samples. Therefore the developed sensor can be applied for the determination of noxious pollutants in real-time monitoring devices.

Selective electrochemical detection of antidepressant drug imipramine in blood serum and urine samples using an antimony telluride-graphite nanofiber electrode.

A high-performance imipramine (IMPR) sensor has been developed  based on metal chalcogenide-carbon composite materials. The antimony telluride-graphite nanofiber (Sb2Te3-GNF, hereafter SBT-GNF) composite was synthesized by the hydrothermal method and confirmed by X-ray powder diffraction (XRD) pattern. The morphology, crystalline lattice, and chemical states were characterized by HRTEM, SAED, and XPS analysis. The characterizations confirmed the formation of an effective composite, SBT-GNF. The SBT-GNF was fabricated as a disposable sensor electrode with a screen-printed carbon electrode (SPCE) and examined for the detection of IMPR by differential pulse voltammetry (DPV). The electroanalytical results of SBT-GNF are compared with the SBT and GNF, and the rational design of effective composite is discussed. SBT-GNF/SPCE showed a good linear range (0.01­51.8 µM), sensitivity (1.35 ± 0.1 µA µM-1 cm-2), and low LOD (4 ± 2 nM). Moreover, the SBT-GNF/SPCE revealed high selectivity and high tolerance limit against potential interfering compounds in blood serum and urine samples. Therefore, this electrochemical sensor can be applicable for the detection of tricyclic antidepressant drug IMPR in clinical and pharmaceutical analysis.

Sonochemical synthesis of samarium tungstate nanoparticles for the electrochemical detection of nilutamide.

This study reports the sonochemical synthesis of samarium tungstate nanoparticles (SWNPs) for applications in electrochemical sensors. The synthesis process is based on a precipitation reaction, which was investigated by ultrasound and compared with the effect of stirring. A bath sonicator operated at a frequency and power of 37/100 kHz and ~60 W, respectively, was employed to prepare the material. The shock waves efficiently irradiated the reaction conditions as much as possible, resulting in the good crystallinity of the monoclinic phase of the SWNPs, which was confirmed by XRD analysis. The surface morphology and structural composition was further evaluated by HRTEM, EDS and XPS. The good crystallinity and uniform distribution of elements in the nanoparticles were confirmed. The performance of the SWNPs to electrochemically sense nilutamide (NLT) was studied, which revealed a good electrochemical signal. As a result, the SWNPs were applied to an electrode material for the detection of NLT. This study revealed the excellent activity of the SWNPs for NLT detection, resulting in a low detection limit (0.0026 µM) and good linear range (0.05-318 µM). Furthermore, the results show appreciable analytical performances, which could be applied to electrochemical anti-androgen drug nilutamide sensors.

Sonochemical preparation of bismuth oxide nanotiles decorated exfoliated graphite for the electrochemical detection of imipramine.

This work described the sonohydrolysis of Bi(NO3)3 into Bi2O3 and simultaneous sonochemical exfoliation of graphite into graphene sheets in the alkaline environment and its electocatalytic performance towards the detection of anti-depression drug imipramine (IMPR). The ultrasound (37/80 kHz; 60 W) effectively hydrolyzed the Bi(NO3)3 into a single crystalline monoclinic phase of Bi2O3 nanotiles in the alkaline condition. And also, the sonochemical reaction condition can trigger the lamellar particles on the graphite bulk surface and allowed to exfoliated the graphite (EG) into graphene nanosheets as well. The material characterizations are done by XRD, Raman, FESEM, and HRTEM. It shows the α-Bi2O3 nanotiles along with EG nanosheets with high crystallinity and low defects. The (0 0 2) plane in XRD confirms the high crystalline nature of EG. The monoclinic stretching vibrations (90-600 cm-1) confirms the Raman modes of Bi2O3. The prepared Bi2O3-EG composites are subjected to the electrochemical determination of IMPR which revealed appreciable analytical performances. The results showed that the Bi2O3-EG exhibits better results in the 3 h sonication process. Bi2O3-EG-3 exhibited a good linear range (0.02-82.3 µM) and an acceptable limit of detection (6 nM). And also Bi2O3-EG-3 exhibits the significant tolerance limit when compared to other potential interfering compounds.

Ethylcellulose assisted exfoliation of graphite by the ultrasound emulsification: An application in electrochemical acebutolol sensor.

This work reports the sonochemical exfoliation of graphite (bath sonication with the frequency of 37/80 kHz and power of 60 W) and its electrocatalytic properties to the ß-blocker drug. The pencil graphite (PG) was exfoliated by the ultrasound emulsification with the support of ethyl cellulose (EC). Herein, EC act as an emulsifier which aids to the exfoliation and also stabilizing the exfoliated graphite. This EC assisted PG (ECPG) was characterized by various analytical techniques which showed that ECPG has high crystalline graphene sheets. In some places, EC submerged to the graphene sheets which improve the dispersibility of graphene in water. The performance of ECPG was evaluated to the electrocatalysis of acebutolol (ACE) which exhibited good electrochemical signal. Therefore, the ECPG was utilized to the detection of ACE as the electrochemical sensor electrode. It showed notable sensitivity (2.87 µA µM-1 cm-2) appreciable linear range (0.01-200 µM) and satisfactory detection limit (4 nM). Furthermore, it displays acceptable anti-interference properties with other interfering ions.