Nano assembly of NiFe spheres anchored on f-MWCNT for electrocatalytic reduction and sensing of nitrofurantoin in biological samples

An enhanced non-enzymatic electrochemical sensor based on the Bi2S3-TiO2 nanocomposite with HNTs for the individual and simultaneous detection of 4-nitrophenol and nitrofurantoin in environmental samples

In the current era of rapid population growth, there has been an increase in resource consumption and the subsequent release of organic pollutants into water bodies by various industries. To address this issue, we have developed a nanocomposite material, Bi2S3-TiO2/HNTs, for electrochemical sensors capable of simultaneously detecting nitrofurantoin (NFT) and 4-nitrophenol (4-NP) contaminants. The nanocomposite material was synthesized using a novel one-pot sol-gel method, and its structural morphology was characterized using techniques such as FE-SEM, FT-IR, HR-TEM, and XRD. The electrochemical sensor exhibited a remarkably low limit of detection (3.2 nM for NFT and 3.5 nM for 4-NP) and a wide concentration range from 0 μM to 260 μM for both NFT and 4-NP, demonstrating their high sensitivity and accuracy for pollutant detection, and furthermore its potential for real-world application was assessed considering pond and tap water as real samples.

Composite of a Stabilizer-Free Trimetallic Prussian Blue Analogue (PBA) and Polyaniline (PANI) on 3D Porous Nickel Foam for the Detection of Nitrofurantoin in Biological Fluids

Herein, a facile and highly effective nonenzymatic electrochemical sensing system is designed for the detection of the antibacterial drug nitrofurantoin (NFT). This electrocatalyst is a combination of a trimetallic Prussian blue analogue and conductive polyaniline coated onto a three-dimensional porous nickel foam substrate. A comprehensive set of physicochemical analyses have verified the successful synthesis. The fabricated electrochemical sensor exhibits an impressively low limit of detection (0.096 nM) and quantification (0.338 nM, S/N = 3.3), coupled with a wide linear range spanning from 0.1 nM to 5 mM and a sensitivity of 13.9 μA nM-1 cm-2. This excellent performance is attributed to the collaborative effects of conducting properties of polyaniline (PANI) and the remarkable redox behavior of the Prussian blue analogue (PBA). When both are integrated into the nickel foam, they create a significantly enlarged surface area with numerous catalytic active sites, enhancing the sensor's efficiency. The sensor demonstrates a high degree of specificity for NFT, while effectively minimizing responses to potential interferences such as flutamide, ascorbic acid, glucose, dopamine, uric acid, and nitrophenol, even when present in 2-3-fold higher concentrations. Moreover, to validate its practical utility, the sensor underwent real sample analysis using synthetic urine, achieving outstanding recovery rates of 118 and 101%.

Photoacid-macroion assemblies: how photo-excitation switches the size of nano-objects

Electrostatic self-assembly of photoacids with oppositely charged macroions yields supramolecular nano-objects in aqueous solutions, whose size is controlled through light irradiation. Nano-assemblies are formed due to electrostatic attractions and mutual hydrogen bonding of the photoacids. Irradiation with UV light leads to the deprotonation of the photoacid and, consequently, a change in particle size. Overall, the hydrodynamic radii of the well-defined photoacid-macroion nano-objects lie between 130 and 370 nm. For a set of photoacids, we determine the acidity constants in the ground and excited state, discuss the sizes of photoacid-macroion nano-objects (by dynamic and static light scattering), their composition and the particle shapes (by small-angle neutron scattering), and relate their charge characteristics to size, structure and shape. We investigate the association thermodynamics and relate nanoscale structures to thermodynamics and, in turn, thermodynamics to molecular features, particularly the ionization energy of the photoacid hydroxyl group proton. Structure-directing effects completely differ from those for previously investigated systems, with hydrogen bonding and entropic effects playing a major role herein. This combined approach allows developing a comprehensive understanding of assembly formation and photo-response, anchored in molecular parameters (pKa, ionization energy, substituent group location), charge characteristics, and the association enthalpy and entropy. This fundamental understanding again paves the way for tailoring application solutions with novel photoresponsive materials.

Facile engineering of gadolinium cobaltite anchored on functionalized carbon black as dynamic electrocatalyst for ultra-sensitive detection of nitroaromatic drug

There has been a significant increase in the production and use of antibiotic drugs. However, the overuse and improper disposal of nitro-based antibiotics pose a significant threat to human health and the ecosystem. Specifically, the residues of antibiotic drugs such as nitrofurantoin (NFT) are dangerous to public health and pose a threat to the environment. In this study, we prepared a novel nanocomposite consisting of gadolinium cobaltite embedded functionalized carbon black (GdCoO3/f-CB) via a simple hydrothermal technique and utilized this nanocomposite as an electrode material for the electrochemical detection of NFT. The structural and morphological properties of the GdCoO3/f-CB nanocomposite was analyzed using a range of techniques, including XRD, Raman, XPS, EDX-Mapping, and HR-TEM. The electrocatalytic activity of the GdCoO3/f-CB nanocomposite was investigated using both CV and DPV techniques for the detection of NFT. Our results demonstrated that the prepared GdCoO3/f-CB nanocomposite delivered the excellent activities toward the detection of NFT at an extremely low limit of detection (LOD) of 2 nM and exhibited high sensitivity of 31 μA·μM-1·cm-2. Additionally, the proposed NFT sensor using GdCoO3/f-CB nanocomposite provided excellent reproducibility, repeatability, and selectivity, even in the presence of interfering molecules such as metal ions, biomolecules, and similar nitro compounds. These findings suggest that the GdCoO3/f-CB nanocomposite provides significant potential for the electrochemical detection of antibiotic drug residues for public health and the environment.

Electrochemical Biosensors for the Detection of Antibiotics in Milk: Recent Trends and Future Perspectives

Antibiotics have emerged as ground-breaking medications for the treatment of infectious diseases, but due to the excessive use of antibiotics, some drugs have developed resistance to microorganisms. Because of their structural complexity, most antibiotics are excreted unchanged, polluting the water, soil, and natural resources. Additionally, food items are being polluted through the widespread use of antibiotics in animal feed. The normal concentrations of antibiotics in environmental samples typically vary from ng to g/L. Antibiotic residues in excess of these values can pose major risks the development of illnesses and infections/diseases. According to estimates, 300 million people will die prematurely in the next three decades (by 2050), and the WHO has proclaimed "antibiotic resistance" to be a severe economic and sociological hazard to public health. Several antibiotics have been recognised as possible environmental pollutants (EMA) and their detection in various matrices such as food, milk, and environmental samples is being investigated. Currently, chromatographic techniques coupled with different detectors (e.g., HPLC, LC-MS) are typically used for antibiotic analysis. Other screening methods include optical methods, ELISA, electrophoresis, biosensors, etc. To minimise the problems associated with antibiotics (i.e., the development of AMR) and the currently available analytical methods, electrochemical platforms have been investigated, and can provide a cost-effective, rapid and portable alternative. Despite the significant progress in this field, further developments are necessary to advance electrochemical sensors, e.g., through the use of multi-functional nanomaterials and advanced (bio)materials to ensure efficient detection, sensitivity, portability, and reliability. This review summarises the use of electrochemical biosensors for the detection of antibiotics in milk/milk products and presents a brief introduction to antibiotics and AMR followed by developments in the field of electrochemical biosensors based on (i) immunosensor, (ii) aptamer (iii) MIP, (iv) enzyme, (v) whole-cell and (vi) direct electrochemical approaches. The role of nanomaterials and sensor fabrication is discussed wherever necessary. Finally, the review discusses the challenges encountered and future perspectives. This review can serve as an insightful source of information, enhancing the awareness of the role of electrochemical biosensors in providing information for the preservation of the health of the public, of animals, and of our environment, globally.

Chemically engineered unzipped multiwalled carbon nanotube and rGO nanohybrid for ultrasensitive picloram detection in rice water and soil samples

Picloram (4-Amino-3,5,6-trichloro pyridine-2-carboxylic acid) is a chlorinated herbicide that has been discovered to be tenacious and relatively durable in both soil and water. It is known to have adverse and unpleasant effects on humans causing several health complications. Therefore, the determination of picloram is profoundly effective because of its bio-accumulative and persistent nature. Because of this, a sensitive, rapid, and robust detection system is essential to detect traces of this molecule. In this study, we have constructed a novel nanohybrid system comprising of an UZMWCNT and rGO decorated on AuNPs modified glassy carbon electrode (UZMWCNT + rGO/AuNPs/GCE). The synthesized nanomaterials and the developed system were characterized using techniques such as SEM, XRD, SWV, LSV, EIS, and chronoamperometry. The engineered sensor surface showed a broad linear range of 5 × 10^-2 nM to 6 × 10⁵ nM , a low limit of detection (LOD) of 2.31 ± 0.02 (RSD < 4.1%) pM and a limit of quantification (LOQ) of 7.63 ± 0.03 pM. The response time was recorded to be 0.2 s, and the efficacy of the proposed sensor system was studied using rice water and soil samples collected from the agricultural field post filtration. The calculated recovery % for picloram in rice water was found to be 88.58%-96.70% (RSD < 3.5%, n = 3) and for soil it was found to be 89.57%-93.24% (RSD < 3.5%, n = 3). In addition, the SWV responses of both the real samples have been performed and a linear plot have been obtained with a correlation coefficient of 0.97 and 0.96 for rice and soil samples, respectively. The interference studies due to the coexisting molecules that may be present in the samples have been found to be negligible. Also, the designed sensor has been evaluated for stability and found to be highly reproducible and stable towards picloram detection.

Bimetallic Cu5Zn8 alloy-embedded hollow porous carbon nanocubes derived from 3D-Cu/ZIF-8 as efficient electrocatalysts for environmental pollutant detection in water bodies

Excessive use of nitrofurantoin (NFT) and its residues can be harmful to the ecosystem, and to mitigate this, rapid and cost-effective detection of NFT in water bodies is needed. In this regard, we prepared a three-dimensional (3D) copper-zeolitic imidazole framework (Cu/ZIF-8)-derived bimetallic Cu₅Zn₈ alloy-embedded hollow porous carbon nanocubes (Cu₅Zn₈/HPCNC) for electrochemical detection of NFT. The resultant material is characterized using suitable spectrophotometry and voltammetry methods. Cu₅Zn₈/HPCNC is an effective electrocatalyst with high electrical conductivity and a fast electron transfer rate. It also has more catalytic active sites for improved electrochemical reduction of NFT. Fabricated Cu₅Zn₈/HPCNC-modified screen-printed electrode (SPE) for NFT reduction have a wide linear range with a low detection limit, and high sensitivity (15.343 μA μМ^-1 cm^-2), appreciable anti-interference ability with related nitro compounds, storage stability, reproducibility, and repeatability. Also, the practicability of Cu₅Zn₈/HPCNC/SPE can be successfully employed in NFT monitoring in water bodies (drinking water, pond water, river water, and tap water) with satisfactory recoveries.

Zinc Oxide/Phosphorus-Doped Carbon Nitride Composite as Potential Scaffold for Electrochemical Detection of Nitrofurantoin

Herein, we present an electrocatalyst constructed by zinc oxide hexagonal prisms/phosphorus-doped carbon nitride wrinkles (ZnO HPs/P-CN) prepared via a facile sonochemical method towards the detection of nitrofurantoin (NF). The ZnO HPs/P-CN-sensing platform showed amplified response and low-peak potential compared with other electrodes. The exceptional electrochemical performance could be credited to ideal architecture, rapid electron/charge transfer, good conductivity, and abundant active sites in the ZnO HPs/P-CN composite. Resulting from these merits, the ZnO HPs/P-CN-modified electrode delivered rapid response (2 s), a low detection limit (2 nM), good linear range (0.01-111 µM), high sensitivity (4.62 µA µM^-1 cm²), better selectivity, decent stability (±97.6%), and reproducibility towards electrochemical detection of NF. We further demonstrated the feasibility of the proposed ZnO HPs/P-CN sensor for detecting NF in samples of water and human urine. All the above features make our proposed ZnO HPs/P-CN sensor a most promising probe for detecting NF in natural samples.

Construction of Electrochemical Sensors for Antibiotic Detection Based on Carbon Nanocomposites

Excessive antibiotic residues in food can cause detrimental effects on human health. The establishment of rapid, sensitive, selective, and reliable methods for the detection of antibiotics is highly in demand. With the inherent advantages of high sensitivity, rapid analysis time, and facile miniaturization, the electrochemical sensors have great potential in the detection of antibiotics. The electrochemical platforms comprising carbon nanomaterials (CNMs) have been proposed to detect antibiotic residues. Notably, with the introduction of functional CNMs, the performance of electrochemical sensors can be bolstered. This review first presents the significance of functional CNMs in the detection of antibiotics. Subsequently, we provide an overview of the applications for detection by enhancing the electrochemical behaviour of the antibiotic, as well as a brief overview of the application of recognition elements to detect antibiotics. Finally, the trend and the current challenges of electrochemical sensors based on CNMs in the detection of antibiotics is outlined.

High-performance electrochemical sensing of hazardous pesticide Paraoxon using BiVO4 nano dendrites equipped catalytic strips

Paraoxon is one of the pesticide that can induce toxicity to nervous system of living organisms. In this work, we focused on synthesizing the catalyst Bismuth Vanadate with the properties that can sense the presence of organophosphorus compounds and characterized them with various characterization methods. The structural studies done by XRD, UV spectroscopy and FTIR spectroscopy. Morphological studies were carried by SEM and TEM. Elemental analysis using XPS spectra. The proposed electrocatalyst was successfully applied as the active electrode material modifying the screen printed carbon electrode for electrochemical sensor applications. The results of the studies indicate that bismuth vanadate modified electrode exhibited four electron transfer process for reduction of nitro group and this lead to the superior electrochemical sensing performance for ethyl Paraoxon with a detection limit of 0.03 μM and good sensitivity 0.345 μA μM^-1 cm^-2 with excellent reproducibility, repeatability, stability and selectivity over common interferents. Furthermore, the practical application was successfully carried using the proposed modified strips to determine Paraoxon presence in the river water sample with satisfactory results. This proposed catalyst can act as a desirable candidate for the rapid electrochemical sensor.

Melamine functionalised multiwalled carbon nanotubes (M-MWCNTs) as a metal-free electrocatalyst for simultaneous determination of 4-nitrophenol and nitrofurantoin

An innovative melamine functionalised multiwalled carbon nanotube (M-MWCNTs) based electrochemical sensor has been developed for the determination of environmental nitro-aromatic pollutants, such as 4-nitrophenol (4-NP) and nitrofurantoin (NFT).

Rational design and preparation of copper vanadate anchored on sulfur doped reduced graphene oxide nanocomposite for electrochemical sensing of antiandrogen drug nilutamide using flexible electrodes

Copper vanadate nanoparticles (Cu₂V₂O₇) are synthesized by using a simple hydrothermal method and later anchored with sulfur-doped reduced graphene oxide (S-rGO) by using ultrasonication to form a hybrid nanocomposite. The synthesized composite underwent characterizations like X-ray diffraction analysis (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), Dynamic ray scattering-Ultra violet-visible spectroscopy (DRS-UV-visible) and X-ray photoelectron spectroscopically revealed the triclinic pattern of the P 1̅ space group of α-Cu₂V₂O₇ and the reduced oxygen deficiency state of metal centers (Cu⁺ or V⁴⁺) resulting with oxides of mixed-valence oxidative states and forming of Cu-O bond. Morphological analysis was carried out by using transmission electron microscopy (TEM) and Field emission scanning electron microscopy (FE-SEM) with elemental mapping and EDX analysis. Furthermore, a novel electrochemical sensor is prepared by using the hybrid sCu₂V₂O₇/S-rGO nanocomposite on to a disposable screen-printed carbon paste electrode (SPCE) for electrochemical sensing of antiandrogen drug nilutamide (NLT). This report reveals excellent activity in determining NLT with a low detection limit of 0.00459 nM for the linear range of 0.001-15 μM with high sensitivity of 26.2605 µA µM^-1 cm^-2. Further, electrode performance showed appreciable performance in real-time monitoring of biological samples like human blood serum, urine samples.

Nanostructured perovskite type gadolinium orthoferrite decorated RGO nanocomposite for the detection of nitrofurantoin in human urine and river water samples

Nitrofurantoin (NFT) is mainly used in humans for the treatment of urinary tract infections. NFT is used as feed additives in animals, due to its broad antimicrobial activity. However, it shows more side effects on human health and the environment. Therefore low-cost, portable, and rapid sensors are necessary for the detection of NFT in real samples. Herein, we successfully developed an electrochemical sensor using a glassy carbon electrode (GCE) modified with gadolinium orthoferrite (GdFeO₃) decorated on reduced graphene oxide (RGO) nanocomposite for the detection of NFT. The facile hydrothermal method was used to synthesis a novel GdFeO₃/RGO nanocomposite, the morphological and structural characterization was confirmed by the FESEM, HRTEM, EDX, XRD, Raman, and XPS techniques. The formation mechanism of GdFeO₃/RGO nanocomposite had been discussed. The effective intercalation of the nanostructured GdFeO₃ to the RGO sheets leads to the significant enhancement in physicochemical properties such as electrical conductivity, electro-active surface area, structural stability, and electrochemical activity, which was observed from the EIS and CV experimental results. The electrochemical studies established that the developed GdFeO₃/RGO sensor was highly sensitive and selective to NFT. Moreover, the GdFeO₃/RGO sensor exhibits good sensitivity of 4.1985 μA μM^-1 cm^-2, a low detection limit (LOD) of 0.0153 µM and a linear range from 0.001 to 249 µM for NFT detection under optimized experimental conditions. In addition, the investigation of storage time on the CV response of the GdFeO₃/RGO sensor indicates superior stability. Owing to these extraordinary analytical advantages, the as-fabricated sensor was applied to detect the NFT levels in human urine and river water samples with satisfactory results.

Facile Synthesis of Ag/AgVO3/N-rGO Hybrid Nanocomposites for Electrochemical Detection of Levofloxacin for Complex Biological Samples Using Screen-Printed Carbon Paste Electrodes

Silver vanadate nanorods (β-AgVO₃) with silver nanoparticles (Ag-NPs) decorated on the surface of the rods were synthesized by using simple hydrothermal technique and later anchored onto nitrogen-doped reduced graphene oxide (N-rGO) to make a novel nanocomposite. Experimental analyses were carried out to identify the electronic configuration by X-ray diffraction analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy analysis, which revealed monoclinic patterns of the C12/m1 space group with Wulff construction forming beta silver vanadate (β-AgVO₃) crystals with optical density and phase transformations. Ag nucleation showed consistent results with metallic formation and electronic changes occurring in [AgO₅] and [AgO₃] clusters. Transmission electron microscopy and field-emission scanning electron microscopy with elemental mapping and EDX analysis of the morphology reveals the nanorod structure for β-AgVO₃ with AgNPs on the surface and sheets for N-rGO. Additionally, a novel electrochemical sensor is constructed by using Ag/AgVO₃/N-rGO on screen-printed carbon paste electrodes for the detection of antiviral drug levofloxacin (LEV) which is used as a primary antibiotic in controlling COVID-19. Using differential pulse voltammetry, LEV is determined with a low detection limit of 0.00792 nm for a linear range of 0.09-671 μM with an ultrahigh sensitivity of 152.19 μA μM^-1 cm^-2. Furthermore, modified electrode performance is tested by real-time monitoring using biological and river samples.

Hydrothermal architecture of Cu5V2O10 nanostructures as new electro-sensing catalysts for voltammetric quantification of mefenamic acid in pharmaceuticals and biological samples

A novel nano-electrocatalyst based on Cu₅V₂O₁₀ is successfully fabricated by one-pot hydrothermal treatment and used for the examination of mefenamic acid (MFA) in real samples, for the first time. Controlling the combined factors of complexing agent's (4, 4'-Diaminodiphenylmethane, DDM) molar ratio, hydrothermal temperature, and reaction time is responsible for providing the optimal structural and morphological changes of the crystals. The effect of operating conditions of Cu₅V₂O₁₀ nanostructures is investigated using FT-IR, XRD, and EDX as structural and elemental analyses. Also, other properties such as particle size and morphological studies were accomplished by FE-SEM, and HR-TEM. The results reveal that the monoclinic phase of Cu₅V₂O₁₀ with particle size of 34 nm is the outcome of hydrothermal treatment of 200 °C for 18 h, which DDM template with molar ratio of 2.0 M serves as phase stabilizing matrix. Herein, it is demonstrated the electrochemical biosensing characteristics of the nano-scale Cu₅V₂O₁₀ modified carbon paste electrode (CV/CPE) by voltammetry techniques. The drug sensing capabilities of the boosted CV/CPE platform exhibit linear dynamic range of 0.01-470 μM, and low detection limit of 2.34 nM with excellent sensitivity and selectivity. The appropriate electrical conductivity and layered structure of the compound causes a valuable platform for minimally invasive assessment of MFA in biological and pharmaceutical media with recovery rate of 98.3%-110.0% and 93.6%-106.7%, respectively. As a result, the proposed nanostructures as great candidate offer excellent electrocatalytic activity in biomedicine applications.