Solvothermal synthesis of silver tungstate integrated with carbon nitrides matrix composites for highly sensitive electrochemical nitrofuran derivative sensing in biological samples

Nanofiber Composites of Poly(vinyl alcohol)/Silver-Based Molybdate and Tungstate Oxide Semiconductors for Antimicrobial Applications

In the present study, powders of α-Ag2WO4 (PAW) and β-Ag2MoO4 (PAM) were prepared through the coprecipitation method, while poly(vinyl alcohol) nanofibers (FPVA) and composite nanofibers of PVA/α-Ag2WO4 (FPAW) and PVA/β-Ag2MoO4 (FPAM) were prepared using the electrospinning technique. Several characterization techniques were applied to evaluate the structure of the obtained materials, as well as studies for assessing their antimicrobial properties. The antimicrobial activities of the composites against Pseudomonas aeruginosa and Staphylococcus aureus were investigated through the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). Our studies demonstrated that materials exhibit antibacterial activity against P. aeruginosa (MIC/MBC = 0.014/ND mg mL-1 for PAW; MIC/MBC = 1.43/1.43 for PAM; MIC/MBC = 1.35/1.35 mg mL-1 for FPAW; MIC/MBC = 3.68/11.03 mg mL-1 for FPAM and MIC/MBC = 8.78/ND mg mL-1 for FPVA) and S. aureus (MIC/MBC = 0.794/ND mg mL-1 for PAW; MIC/MBC = 1.43/ND for PAM; MIC/MBC = 1.35/1.35 mg mL-1 for FPAW; MIC/MBC = 3.68/3.67 mg mL-1 FPAM and MIC/MBC = 14.63/* mg mL-1 for FPVA). The cytotoxic concentrations (CC50, μg mL-1) against the VERO cells were 21.74 ± 0.04 for PAW, <15 for PAM, 103.70 ± 18.90 for FPAW, 111.22 ± 4.02 for FPAM, and >1000 for FPVA, thus indicating that the immobilization of the semiconductor to the FPVA mats decreases the cytotoxic effect of the materials studied as compared to not immobilized ones. The results suggest that powders and composite polymeric mats displayed antimicrobial action that was attributed to the production of reactive oxygen species (ROS), which are responsible for inducing high local oxidative stress, causing the death of both types of bacteria.

A comprehensive review on the pretreatment and detection methods of nitrofurans and their metabolites in animal-derived food and environmental samples

In recent years, the residues of nitrofurans (NFs) and their metabolites in animal-derived food and environmental samples have gained widespread attention. The parent drugs and their metabolites have displayed significant toxicity to human health including carcinogenic, mutagenic and teratogenic effects, leading to banned in animal husbandry in many countries. Hence, monitoring the residues of NFs is necessary to guarantee public health and ecological security. This review aims to summarize and assess the structural properties, residue status, sample pretreatment methods (liquid-liquid extraction, solid-phase extraction, Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS), and field-assisted extraction), and detection methods (chromatographic analysis, immunoassay, and some innovative detection methods) for NFs and their metabolites in animal-derived food and environmental samples. This paper provides a detailed reference and discussion for the analysis of NFs and their metabolites, which can effectively promote the establishment of innovative detection methods for NFs and their metabolites residues.

Electrochemical DNA Sensor Designed Using the Pencil Graphite Electrode to Detect Listeria monocytogenes

In the present work, a novel electrochemical DNA sensor was designed to detect L. monocytogenes. Two different gene fragments were selected for the sensor design. One is a 702 bp long fragment of the hlyA gene, encoding the synthesis of listeriolysin O toxin, which is unique only to pathogenic strains of L. monocytogenes and is essential for pathogenicity. The other is a 209 bp long fragment of the 16 S RNA gene found in all species of the Listeria genus. As the working electrode, the pencil graphite electrode was modified in various ways (activated or covered with polypyrrole), and six different combinations were constituted using three types of the modified working electrode and two different gene fragments. The developed system is based on differential pulse voltammetric transduction of guanine oxidation after hybridization between the selected gene fragment (38 µg/mL) and the selected fragment-specific inosine-modified probe (1.8 µmol/L) immobilized on a pencil graphite electrode surface. The comparison of all combinations demonstrates that the best results are obtained with the combination formed from a polypyrrole-coated pencil graphite electrode (prepared at 2 scans) and 702 bp fragment of the hlyA gene. The analysis time is less than 1 hour, and the necessary DNA concentrations for the analysis have been determined as 8.2 × 10-11 M DNA and 2.7 × 10-10 M DNA respectively, for the hlyA gene and 16 S RNA gene.

Construction of functionalized carbon nanotube@metal oxide nanocomposite for high-performance electrochemical measurement of antipyretic drug in water samples

Acetaminophen (AP) acts as supportive clinical therapy for fever and dysmenorrhea. An overdose of AP may result in severe adverse diseases, such as liver dysfunction. In addition, AP is a key-listed environmental pollutant, which is difficult to degrade in the environment and has serious effects on living bodies. Therefore, the simple and quantitative determination of AP is highly relevant today. In this work, tin dioxide (SnO2) nanoparticles with functionalized multi-walled carbon nanotube (f-MWCNT) as a hybrid composite were prepared by hydrothermal-assisted synthesis. The composite material was characterized by various spectral, morphological, and electrochemical tests. Electrochemical investigations were conducted using a SnO2@f-MWCNT-reinforced electrode for the detection of AP. The composite electrode exhibited better functional properties, which facilitated electron transfer and enhanced electrical conductivity. The calculated low detection limit (LOD) of 0.36 nM is with a wide linear range of concentration from 0.001 to 673 µM. Additionally, the SnO2@f-MWCNT-modified electrode exhibited good anti-interference capability, repeatability, reproducibility, storage, and operational stability. The developed SnO2@f-MWCNT-modified electrode was applied to practical analysis in diverse water matrices (river, drinking, and pond) with acceptable recovery percentages. A synthesized nanoscale metal oxide electrocatalyst is of great interest and an active research area that serves as a foundation for the development of new, cost-effective electrochemical antibiotic drug sensors.

Rare [Cu4I2]2+ cationic cluster-based metal-organic framework and hierarchical porous composites design for effective detection and removal of roxarsone and antibiotics

Fluorescence quenching induced by photoinduced electron transfer (PET) stands as an effective strategy for identifying water pollutants. Herein, a novel (4, 8)-connected three-dimensional framework Cu(I)-MOF ([Cu2I(tpt)]n) with unique 8-connected [Cu4I2]2+ cationic clusters is designed by employing the nitrogen-rich ligand (Htpt = 5-[4(1H-1,2,4-triazol-1-yl)]phenyl-2H-tetrazole). Water-stabilized Cu(I)-MOF exhibits outstanding fluorescence properties, facilitating its application in detecting organic pollutants in water. Benefiting from the fact that the Cu(I)-MOF possesses a higher lowest unoccupied molecular orbitals (LUMO) energy level than that of the analyte, the rapid d-PET can occur, entitling Cu(I)-MOF to a sensitive fluorescence quenching response to roxarsone (ROX), nitrofurazone (NFZ) and nitrofurantoin (NFT) (with detection limits as low as 0.13 µM, 0.15 µM, and 0.13 µM, respectively). The nitrogen-containing sites of melamine foam (MF) are utilized to facilitate the anchoring and growth of Cu-MOF crystals, which enables the preparation of hierarchical microporous - macroporous Cu(I)-MOF/MF composites. The ordered porous structure of Cu(I)-MOF/MF provides cavities and open sites for the efficient removal of ROX (qmax = 210.6 mg∙g-1), NFZ (qmax = 111.5 mg∙g-1) and NFT (qmax = 238.9 mg∙g-1) from water. This characteristic endows the Cu(I)-MOF/MF with rapid and recyclable adsorption capacity. Therefore, this work provides valuable insights to address the problem of detection and removal of pollutants in the aquatic environment.

Composite of a thiacalix[4]arene-copper(I) metal-organic framework and mesoporous carbon for efficient electrochemical detection of antibiotics

Abundant use of nitrofurantoin (NFT) and metronidazole (MTZ) antibiotics has led to excessive residues in the environments and humans, resulting in serious damage to the human body and ecosystem. Therefore, effective detection of NFT and MTZ is exceedingly necessary. In this regard, metal-organic frameworks (MOFs) are promising materials as electrochemical sensors. Herein, we synthesized a new two-dimensional thiacalix [4]arene-copper (I) MOF (Cu-TC4A-M). This MOF was mixed with mesoporous carbon (MC) to a give Cu-TC4A-M@MC composite. In addition, the sensors of Cu-TC4A-M@MC(2:1)/GCE and Cu-TC4A-M@MC(1:2)/GCE were achieved (GCE = glassy carbon electrode), and then were applied for effectively detecting NFT and MTZ, respectively. Markedly, the two sensors exhibited satisfactory linear detection range, anti-interference, reproducibility and stability. When they were utilized in the real samples, such as human serum, urine, tap water and lake water, satisfactory recoveries were attained. The relative standard deviations (RSDs) were in the range of 1.16 % ∼ 1.92 % for NFT and 0.95 % ∼ 2.33 % for MTZ. This work provided a new application prospect for the thiacalix [4]arene-based MOFs as promising candidate materials for NFT and MTZ detection.

Development of novel microsphere structured - calcium tungstate as efficacious electrocatalyst for the detection of antibiotic drug nitrofurantoin

In this report, synthetic and nitro groups containing antibiotic drug nitrofurantoin (NFT) were electrochemically quantified under amended conditions using novel constructed calcium tungstate microspheres modified on glassy carbon electrodes (CTMs/GCE). The calcium tungstate microspheres (CTMs) were synthesized by a facile sonochemical method and characterizations were done by various techniques, such as X-ray diffraction spectrometry (XRD), Fourier transform infrared spectroscopy (FTIR), Raman, field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Ahead of this, electrochemical investigations were performed using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), amperometry, and linear sweep voltammetry (LSV). The synthesis of CTMs as well-distributed microspheres allows more active metal sites regarding and remarkable electrocatalytic activity towards NFT detection with excellent sensitivity (0.724 μA μM-1 cm-2) and low detection limit (21 nmol L-1) with a wide linear range 10-140 μM. The practical feasibility of the developed CTMs/GC electrode was elucidated using distinct real sample river tap water and clinical sample (NFT capsule), and thus, the modified electrode manifested acceptable recovery results.

Lanthanum vanadate-based carbon nanocomposite as an electrochemical probe for amperometric detection of theophylline in real food samples

Theophylline (THP) is an emerging drug for chronic obstructive pulmonary disease whose side effects can be greatly affected by caffeine-containing real foods. Because an overdose of this substance can cause respiratory and neurological damage, producing a fast and accurate analytical procedure is critical. Based on a cutting-edge hybrid nanocomposite, this study was used to construct an electrochemical sensor for the accurate detection of THP. Spectroscopy and morphological investigation supported the easy synthesis of tetragonal-LaVO₄ (t-LV) nanopellets and LV@CNF hybrid nanocomposite. To detect THP, a highly dispersed LV@CNF nanocomposite was modified on a glassy carbon electrode as a sensing substrate. By amperometric technique, the sensor shows a wide linear range of 0.01-1070 μM, low limit of detection (2.63 nM), and sensitivity (0.228 μA μM^-1 cm^-2). Finally, the current technique was successfully used to identify THP in real food samples (chocolate, coffee and black tea).

A sonochemical synthesis of SrTiO3 supported N-doped graphene oxide as a highly efficient electrocatalyst for electrochemical reduction of a chemotherapeutic drug

A sonochemical based green synthesis method playa powerful role in nanomaterials and composite development. In this work, we developed a perovskite type of strontium titanate via sonochemical process. SrTiO₃ particles were incorporated with nitrogen doped graphene oxide through simple ultrasonic irradiation method. The SrTiO₃/NGO was characterized by various analytical methods. The nanocomposite of SrTiO₃/NGO was modified with laser-induced graphene electrode (LIGE). The SrTiO₃/NGO/LIGE was applied for electrochemical sensor towards chemotherapeutic drug detection (nilutamide). Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques have been used to examine the electrochemical performance of nilutamide (anti-cancer drug). DPV was found to be more sensitive and found to exhibit a sensitivity 8.627 µA µM^-1 cm^-2 for SrTiO₃/NGO/LIGE with a wide linear range (0.02-892 µM) and low Limit of detection (LOD: 1.16 µM). SrTiO₃/NGO/LIGE has been examined for the detection of nilutamide in blood serum and urine samples and obtained a good recovery in the range of 97.2-99.72 %. The enhanced stability and selectivity and practical application results indicates the suitability of SrTiO₃/NGO/LIGE towards the detection of nilutamide drug in pharmaceutical industries.

Sonochemical construction of hierarchical strontium doped lanthanum trisulfide electrocatalyst: An efficient electrode for highly sensitive detection of ecological pollutant in food and water

Herbicides are used constantly in agriculture to enhance productivity across the globe. This herbicide monitoring requires utmost importance since its high dose leads to ecological imbalance and a negative impact on the environment. Moreover, a quantification of toxic herbicide is one of the important problems in the food analysis. In this work, deals with the development of a simple, and facile one-pot sonochemical synthesis of strontium doped La2S3 (Sr@La2S3). Morphological and structural characterization confirms the doping of Sr@La2S3 to generate a hierarchical layered structure. The electrochemical performance of modified with rotating disk electrode (RDE) using Sr@La2S3 composite is high, compared to La2S3 and bare electrodes towards the quantitative detection of mesotrione (MTO) in phosphate buffer. Sr@La2S3/RDE showed good sensitivity for MTO detection and it exhibit a range of 0.01-307.01 μM and limit of detection of 2.4 nM. Besides, the selectivity of fabricated electrode is high as it can electrochemically reduce MTO particularly, even in the presence of other chemicals, biological molecules and inorganic ions. The repeatability of MTO detection is high even after 30 days with a lower RSD values. Hence, simple fabrication of Sr@La2S3/RDE could be a novel electrode for the sensitive, selective, and reproducible determination of herbicides in real-time applications.

An optical and electrochemical sensor based on L-arginine functionalized reduced graphene oxide

The electrochemical and photochemical properties of graphene derivatives could be significantly improved by modifications in the chemical structure. Herein, reduced graphene oxide (RGO) was functionalized with L-arginine (L-Arg) by an amidation reaction between the support and amino acid. Deposition of a powerful ligand, L-Arg, on the optically active support generated an effective optical chemosensor for the determination of Cd(II), Co(II), Pb(II), and Cu(II). In addition, L-Arg-RGO was used as an electrode modifier to fabricate L-Arg-RGO modified glassy-carbon electrode (L-Arg-RGO/GCE) to be employed in the selective detection of Pb(II) ions by differential pulse anodic stripping voltammetry (DP-ASV). L-Arg-RGO/GCE afforded better results than the bare GCE, RGO/GCE, and L-Arg functionalized graphene quantum dot modified GCE. The nanostructure of RGO, modification by L-Arg, and homogeneous immobilization of resultant nanoparticles at the electrode surface are the reasons for outstanding results. The proposed electrochemical sensor has a wide linear range with a limit of detection equal to 0.06 nM, leading to the easy detection of Pb(II) in the presence of other cations. This research highlighted that RGO as a promising support of optical, and electrochemical sensors could be used in the selective, and sensitive determination of transition metals depends on the nature of the modifier. Moreover, L-Arg as an abundant amino acid deserves to perch on the support for optical, and electrochemical determination of transition metals.

Design of a Novel Nanosensors Based on Green Synthesized CoFe2O4/Ca-Alginate Nanocomposite-Coated QCM for Rapid Detection of Pb(II) Ions

Pb(II) is a significant contaminant that is known to have negative effects on both humans and animals. Recent industrial operations have exacerbated these consequences, and their release of several contaminants, including lead ions, has drawn attention to the potential effects on human health. Therefore, there is a lot of interest in the rapid, accurate, and selective detection of lead ions in various environmental samples. Sensors-based nanomaterials are a significant class among the many tools and methods developed and applied for such purposes. Therefore, a novel green synthesized cobalt ferrite (CoFe₂O₄) nanoparticles and functionalized CoFe₂O₄/Ca-alginate nanocomposite was designed and successfully synthesized for the fabrication of nanoparticles and nanocomposite-coated quartz crystal microbalance (QCM) nanosensors to detect the low concentrations of Pb(II) ions in the aqueous solutions at different temperatures. The structural and morphological properties of synthesized nanoparticles and nanocomposite were characterized using different tools such as X-ray diffraction (XRD), N₂ adsorption-desorption isotherm, dynamic light scattering (DLS), zeta potential analyzer (ζ-potential), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX). The QCM results revealed that the green synthesized CoFe₂O₄ nanoparticles and functionalized CoFe₂O₄/Ca-alginate nanocomposite-coated QCM nanosensors exhibited high sensitivity, stability, and rapid detection of Pb(II) ions in the aqueous solutions at different temperature. The lowest detection limit for Pb(II) ions in the aqueous solutions could reach 125 ng, which resulted in a frequency shift of 27.49 ± 0.81, 23.63 ± 0.90, and 19.57 ± 0.86 Hz (Δf) for the QCM detector coated with green synthesized CoFe₂O₄ nanoparticles thin films, and 25.85 ± 0.85, 33.87 ± 0.73, and 6.87 ± 0.08 Hz (Δf) for the QCM detector coated with CoFe₂O₄/Ca-Alg nanocomposite thin films in a real-time of about 11, 13, and 13 min at 25 °C, 35 °C, and 45 °C, respectively. In addition, the resonance frequency change results showed the superiority of functionalized CoFe₂O₄/Ca-alginate nanocomposite coated QCM nanosensor over CoFe₂O₄ nanoparticles towards Pb(II) ions detecting, which attributed to the beneficial properties of alginate biopolymer.

Sonochemical synthesis of inorganic cryogel Ag2Mo3O10@Ag/AgO: structural characterization, antibacterial activity, and dye adsorption properties

An additive-free ultrasonic-assisted synthesis of a multi-layered Ag₂Mo₃O₁₀@Ag/AgO cryogel (SMSSO) nanocomposite has been developed, and a possible formation mechanism of multi-layered SMSSO was proposed based on characterization results of scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Raman spectroscopy, and diffuse reflection spectroscopy (DRS). The FE-SEM images demonstrated the formation process of the multi-layered SMSSO cryogel over time under sonication, starting with the growth of Ag₂Mo₃O₁₀ nanowires, and the formation of spherical nuclei which turn into an octahedron in the presence of excess silver ions. The antibacterial activity of the synthesized cryogel and its adsorption behavior for hazardous pollutant removal were explored. The results revealed that SMSSO exhibits excellent adsorption properties, with a maximum adsorption capacity of 277.77 mg g⁻¹ and removal of 99/95% for 150 mg L⁻¹ methylene blue (MB) by 0.005 g adsorbent doses at 60 °C and pH 9. It was also confirmed that the synthesized cryogels have good antibacterial activities against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The selective adsorption capability of the cryogel toward cationic dye molecules and antibacterial activity makes it a competent candidate for water purification.

An ultrasonic-assisted synthesis of Ag₂Mo₃O₁₀@Ag/AgO cryogel (SMSSO) nanocomposite was developed, and a possible formation mechanism of multi-layered SMSSO was proposed based on characterization results of SEM, EDX, XRD, Raman spectroscopy, and DRS.