Ultrasonic energy-assisted preparation of β-cyclodextrin-carbon nanofiber composite: Application for electrochemical sensing of nitrofurantoin

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%.

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.

Recent advances in morphology, aperture control, functional control and electrochemical sensors applications of carbon nanofibers

Among many nanomaterials, electrospun carbon nanofibers (CNFs) have become one of the hot spots in nanoscience research because of their interesting physicochemical and biological properties such as large specific surface area, easy functionalization and biocompatibility. Polyacrylonitrile（PAN) has also become the most widely used precursor fiber for CNF manufacturing. In this paper, the latest advances in the synthesis of CNF by electrospinning were reviewed, including using template method, heat treatment, coaxial spinning technology to control the morphology and aperture, as well as the functionalization of electrospinning doped with chemical substances such as heteroatoms, nanoparticles (NPs), carbon nanotubes (CNTs) and grapheme (Gr), in order to further expand its application scope. The application of electrospun CNFs as electrochemical sensing platform for toxic and harmful substances in food and environment was also briefly introduced.

Ag-Ag2O decorated multi-walled carbon nanotubes/NiCoAl hydrotalcite sensor for trace nitrite quantification

Ag-Ag₂O-decorated multiwall carbon nanotube/NiCoAl-hydrotalcite (CNT/LDH-Ag) composites were designed and synthesized for nitrite quantification. The materials were characterized by various techniques, and their electrochemical NO₂^- detection performances investigated using amperometric and differential pulse voltammetry (DPV) techniques. The Ag-Ag₂O nanoparticles (NPs) were anchored on the surface of the CNT/LDH-Ag composites. At a suitable amount of the Ag-Ag₂O loading, the Ag-Ag₂O NPs with small particle size were distributed evenly on the CNT/LDH surface, increasing the surface area of the composites. The optimal CNT/LDH-Ag₃ composite exhibited a high electrochemical activity for NO₂^- oxidation in pH 7.0. Furthermore, the optimal CNT/LDH-Ag₃ composite was fabricated for trace NO₂^- quantification. The proposed sensor displayed a high sensitivity (0.0960 μA·μM^-1·cm^-2) and fast response (< 3 s) toward NO₂^- in a wide linear range from 0.250 μmol·L^-1 to 4.00 mmol·L^-1 with a low detection limit of 0.0590 μmol·L^-1(S/N = 3). The sensor provided an outstanding analytical performance with a desirable recovery (95.3 ~ 107%, RSD < 1.05%) in real sample. As a result, the proposed sensor can be used for the real-time quantification of trace NO₂^- in the biological, food, and environmental fields.

A novel electrochemical sensor based on β-cyclodextrin functionalized carbon nanosheets@carbon nanotubes for sensitive detection of bactericide carbendazim in apple juice

Carbendazim (CBZ) abuse always causes the over-standard of pesticide residues in agricultural products, which has adverse effects on human health. Herein, a novel electrochemical sensor was firstly fabricated based on the β-cyclodextrin (β-CD) functionalized carbon nanosheets@carbon nanotubes (CNS@CNT) for the CBZ determination. CNS@CNT combined large surface area of CNS and excellent electrical conductivity of CNT, which significantly enhanced the electrocatalytic performance. Moreover, β-CD possessed excellent host-gest supramolecular recognition ability, which could improve the selective recognition and enrichment capability of CBZ. Thanks to the synergistic interaction of CNS@CNT and β-CD, the β-CD/CNS@CNT/GCE sensor exhibited a low limit of detection of 9.4 nM in the linear CBZ concentration range of 0.03-30 μM. The fabricated sensor presented favorable stability, high sensitivity (30.86 μA μM^-1 cm^-2), and reliable reproducibility (RSD = 3.6%). Especially, the β-CD/CNS@CNT/GCE sensor could show pretty practical feasibility for the detection of CBZ in apple juice with recoveries of 97.1%-99.4%.

Perspective on Nanofiber Electrochemical Sensors: Design of Relative Selectivity Experiments

The use of nanofibers creates the ability for non-enzymatic sensing in various applications and greatly improves the sensitivity, speed, and accuracy of electrochemical sensors for a wide variety of analytes. The high surface area to volume ratio of the fibers as well as their high porosity, even when compared to other common nanostructures, allows for enhanced electrocatalytic, adsorptive, and analyte-specific recognition mechanisms. Nanofibers have the potential to rival and replace materials used in electrochemical sensing. As more types of nanofibers are developed and tested for new applications, more consistent and refined selectivity experiments are needed. We applied this idea in a review of interferant control experiments and real sample analyses. The goal of this review is to provide guidelines for acceptable nanofiber sensor selectivity experiments with considerations for electrocatalytic, adsorptive, and analyte-specific recognition mechanisms. The intended presented review and guidelines will be of particular use to junior researchers designing their first control experiments, but could be used as a reference for anyone designing selectivity experiments for non-enzymatic sensors including nanofibers. We indicate the importance of testing both interferants in complex media and mechanistic interferants in the selectivity analysis of newly developed nanofiber sensor surfaces.

Tunable and tough porous chitosan/β-cyclodextrin/tannic acid biocomposite membrane with mechanic, antioxidant, and antimicrobial properties

Herein, tannic acid (TA)-reinforced chitosan (CHS)/β-cyclodextrin (β-CD) biocomposite membranes were prepared by TA solution incubating treatment. The functional groups, crystal structure, and morphological characterizations of the prepared biocomposite membranes were investigated using various methods. The biocomposite membranes were investigated in terms of their wettability, porosity, swelling degree, and water uptake. In vitro antioxidant investigation was carried out through DPPH assay. Moreover, the prepared biocomposite membranes were evaluated for their antimicrobial ability against three different microbial species. The introduction of TA effectively improved the swelling behavior, mechanical strength, and porosity of the biocomposite membranes. TA increased the tensile strength from 0.7 ± 0.2 MPa to a maximum of 2.2 ± 0.6 MPa and elongation at break from 26.9 ± 0.7% to a maximum of 36.7 ± 3.5%. The biocomposite membranes showed an initial burst release of TA (~40%) within 6 h, followed by a gradual release of 100% by 18 h. Furthermore, the introduction of TA into the biocomposite membranes further improved the antimicrobial activities against both bacteria and yeast, as well as the in vitro antioxidant potential. As a consequence, the prepared biocomposite membranes could potentially be used as scaffold in broaden biomedical fields due to their adaptable structure, porosity, greatly antioxidant, and antimicrobial activity.

da Silva Alves D, Okeke C, Breslin CB. Cyclodextrins as Supramolecular Recognition Systems: Applications in the Fabrication of Electrochemical Sensors

Supramolecular chemistry, although focused mainly on noncovalent intermolecular and intramolecular interactions, which are considerably weaker than covalent interactions, can be employed to fabricate sensors with a remarkable affinity for a target analyte. In this review the development of cyclodextrin-based electrochemical sensors is described and discussed. Following a short introduction to the general properties of cyclodextrins and their ability to form inclusion complexes, the cyclodextrin-based sensors are introduced. This includes the combination of cyclodextrins with reduced graphene oxide, carbon nanotubes, conducting polymers, enzymes and aptamers, and electropolymerized cyclodextrin films. The applications of these materials as chiral recognition agents and biosensors and in the electrochemical detection of environmental contaminants, biomolecules and amino acids, drugs and flavonoids are reviewed and compared. Based on the papers reviewed, it is clear that cyclodextrins are promising molecular recognition agents in the creation of electrochemical sensors, chiral sensors, and biosensors. Moreover, they have been combined with a host of materials to enhance the detection of the target analytes. Nevertheless, challenges remain, including the development of more robust methods for the integration of cyclodextrins into the sensing unit.

Recent development of antibiotic detection in food and environment: the combination of sensors and nanomaterials

In recent years, the abuse of antibiotics has led to the pollution of soil and water environment, not only poultry husbandry and food manufacturing will be influenced to different degree, but also the human body will produce antibody. The detection of antibiotic content in production and life is imperative. In this review, we provide comprehensive information about chemical sensors and biosensors for antibiotic detection. We classify the currently reported antibiotic detection technologies into chromatography, mass spectrometry, capillary electrophoresis, optical detection, and electrochemistry, introduce some representative examples for each technology, and conclude the advantages and limitations. In particular, the optical and electrochemical methods based on nanomaterials are discussed and evaluated in detail. In addition, the latest research in the detection of antibiotics by photosensitive materials is discussed. Finally, we summarize the pros and cons of various antibiotic detection methods and present a discussion and outlook on the expansion of cross-scientific areas. The synthesis and application of optoelectronic nanomaterials and aptamer screening are discussed and prospected, and the future trends and potential impact of biosensors in antibiotic detection are outlined.Graphical abstract.

Amorphous cobalt boride nanosheets anchored surface-functionalized carbon nanofiber: An bifunctional and efficient catalyst for electrochemical sensing and oxygen evolution reaction

Development of new metal boride with carbon composite is an emerging class of catalyst and it brings enormous curiosity in the material community because of their potential intriguing properties. Here, we describe a new type of amorphous cobalt boride (A-CoB) nanosheet anchored on the surface of functionalized carbon nanofiber (A-CoB/ƒ-CNF) by a simple method. The emerged A-CoB/ƒ-CNF composite was demonstrated to possess great bifunctional electrocatalytic activity for the electrochemical sensing of antibiotic drug nitrofurantoin (NFT) and oxygen evolution reaction (OER). The prepared A-CoB/ƒ-CNF composite was characterized by various analytical and spectroscopic techniques such as XRD, FE-SEM, HR-TEM, Raman, and XPS analysis. The result from the electrochemical impedance spectroscopy confirms that the A-CoB/ƒ-CNF composite shows high electrical conductivity and the number of electron transferability for the NFT sensor and OER which is due to the presence of abundant active sites/large surface area in A-CoB, and synergistic effect between the A-CoB and ƒ-CNF. As an electrochemical sensor, the A-CoB/ƒ-CNF modified electrode shows substantial sensitivity (3.13 μA μM^-1 cm^-2), wider linear response range (0.01- 527 μM), and lower detection limit (0.003 μM) as-compared to the previously reported noble and non-noble metal-based electrocatalyst for NFT sensor. As well, the A-CoB/ƒ-CNF composite demonstrates superior OER activity with low overpotential and small Tafel slope value of 0.35 V and 173 mV/dec, respectively, which shows advanced kinetics than noble metal catalysts. Based on the results, we believed that the present work gives clear evidence for the preparation of transition metal boride anchored carbon material with an outstanding catalytic activity, and hence, it can be also extended to further electrochemical applications.

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

The current study reports a facile simple, low-cost electrochemical sensor in the detection of nitrofurantoin (NFT) by using NiFe/f-MWCNT hybrid composite as a promising electrocatalyst. NFT is an antibiotic drug that is extensively using in pharmaceuticals and also in animal food production which causes a severe threat for both human and animal environments. Extending the residues of NFT are left into rivers, soils, lakes, and groundwaters either found or discharged leading health issues. To this NiFe/f-MWCNT composite was synthesized using a hydrothermal mechanism and then ultrasonicated to form a hybrid composite for catalytic evaluation and electrochemical detection of NFT for the very first time. Furthermore, the physicochemical properties of NiFe nanospheres conjugated on f-MWCNT are scrutinized using various analytical and spectroscopical techniques. Resulting transmission electron microscopy (TEM) displays a chain like NiFe nanospheres anchored on f-MWCNT with a well-defined spherical shape, without any comprehensive agglomeration. The NiFe/f-MWCNT screen printed carbon paste electrode (SPCE) displayed an excellent electrocatalytic activity for NFT with a LOD of 0.03 µM and a sensitivity of 11.45 µA µM^-1 cm^-2. establishing a new selectivity and with the existence of co-interfering compounds. To enhance the practical abilities analysis were performed in Human serum and urine samples which resulted in satisfactory recoveries with high precision and linear accuracy illustrated in Scheme 1.

Ultrasonic assisted functionalization of MWCNT and synergistic electrocatalytic effect of nano-hydroxyapatite incorporated MWCNT-chitosan scaffolds for sensing of nitrofurantoin

In the present work, we report the fabrication of stable composite of chitosan hydrogels (CHI) on multiwalled carbon nanotubes (MWCNT) using a simple ultrasonic-assisted method. Also, rod-like hydroxyapatite nanoparticles (HA NPs) were synthesised using a hydrothermal route and were incorporated into the highly conductive MWCNT-CHI scaffolds using an ultrasonication method. The functionalization of MWCNT and preparation of HA NPs on MWCNT-CHI nanocomposite were done using the sonication over the frequency of 37 kHz with the ultrasonic power capable of 150 W (Elmasonic Easy 60H bath sonicator). The resulting hybrid HA NPs/MWCNT-CHI nanocomposites have an excellent surface area and high surface to volume ratio, which leads to the sensitive detection of nitrofurantoin than pristine MWCNT and HA NPs. The complete elemental and morphological analyses of the HA NPs/MWCNT-CHI nanocomposites were characterised by XRD, FTIR, RAMAN, FESEM, TEM, EDX, and elemental mapping techniques. Electrochemical analysis of the HA NPs/MWCNT-CHI nanocomposites was carried out by cyclic voltammetry, electrochemical impedance spectroscopy and amperometry methods. The modified glassy carbon electrode (GCE) of HA NPs/MWCNT-CHI nanocomposites exhibit the nitrofurantoin detection activity at the linear range of 0.005-982.1 µM with the detection limit of 1.3 nM. The synergistic electrocatalytic activity of HA NPs/MWCNT-CHI nanocomposites modified GCE is correlated to the sensitivity of 0.16 µAµM^-1 cm^-2 with excellent precision and accuracy towards the sensing of nitrofurantoin.

Highly sensitive electrode materials for the voltammetric determination of nitrofurantoin based on zinc cobaltate nanosheets

Schematic illustration of the electrocatalytic activity of nitrofurantoin (NFT) on ZnCo₂O₄ nanosheets.

Facile synthesis of ultrathin NiSnO3 nanoparticles for enhanced electrochemical detection of an antibiotic drug in water bodies and biological samples

The highly sensitive real-time detection of antibiotic drugs (nitrofurantoin; NFT) has drawn significant research attention due to the extensive use of antibiotics, which may cause serious threats to environment as well as living things.

Facile, low-temperature synthesis of tungsten carbide (WC) flakes for the sensitive and selective electrocatalytic detection of dopamine in biological samples

Transition metal carbides have shown potential for use in electrochemical applications due to their excellent electronic conductivity, stability and electrocatalysis.