Enhanced oxidation and detection of toxic ractopamine using carbon nanotube film-modified electrode

A cutting-edge electrochemical sensing platform for the simultaneous determination of the residues of antimicrobial drugs, rifampicin and norfloxacin, in water samples

BACKGROUND

The widespread use and abuse of antibiotics has resulted in the pollution of water sources with antibiotic residues, posing a threat to human health, the environment, and the economy. Therefore, a highly sensitive and selective method is required for their detection in water samples. Herein, advanced ultrasensitive electrochemical sensor platform was developed by integrating gold-silver alloy nanocoral clusters (Au-Ag-ANCCs) with functionalized multi-walled carbon nanotube-carbon paste electrode (f-MWCNT-CPE) and choline chloride (ChCl) nanocomposites for simultaneously determining the residues of antimicrobial drugs, rifampicin (RAMP) and norfloxacin (NFX), in water samples.

RESULTS

The developed sensor (Au-Ag-ANCCs/f-MWCNTs-CPE/ChCl) was extensively characterized using several analytical (UV-Vis, FT-IR, XRD, SEM, and EDX) and electrochemical (EIS, CV, and SWV) techniques. It exhibited outstanding performance in a wide linear range, from 14 pM to 115 μM for RAMP, and from 0.9 nM to 200 μM for NFX, with a limit of detection (LOD, 3σ/m, S/N = 3, n = 5) and a limit of quantification (LOQ, 10σ/m, S/N = 3, n = 5) values of 2.7 pM and 8.85 pM for RAMP, and 0.14 nM and 0.47 nM for NFX, respectively. The sensor also exhibited exceptional reproducibility, stability, and resistance to interference.

SIGNIFICANCE

The developed sensor was effectively utilized to determine RAMP and NFX residues in hospital wastewater, river, and tap water samples, yielding recoveries within the range of 96.8-103 % and relative standard deviations below 5 %. Generally, the proposed sensor demonstrated remarkable performance in detecting the target analytes, making it an ideal tool and the first of its kind for addressing global antibiotic residue pollutants in water sources.

Nanomolar electrochemical detection of feed additive ractopamine in meat samples using spinel zinc ferrite decorated 3-dimensional graphene nanosheets to combat food fraud in livestock industries

Accurate detection of feed additive is significant for food safety monitoring, warding off its illegal use in livestock production, safeguarding public health, and regulatory compliance. Hence, this paper presents a cost-effective and ultrasensitive electrochemical sensor for detecting commonly used animal feed additive, ractopamine to combat food frauds in meat samples. The sensor was created by embedding spinel zinc ferrite nanospheres (ZnFe2O4) on three-dimensional graphene (3DG) nanosheets using sonochemical method. ZnFe2O4 nanospheres were synthesized using solvothermal approach, and 3DG was prepared using hydrothermal method. Various characterization techniques were used for inspecting structural and morphological properties of materials, including XRD, SEM, TEM, elemental mapping, Raman spectroscopy, XPS, and EIS. The hybrid nanocomposite modified electrode showed excellent electrochemical performance, with high sensitivity of 16.97 μA μM-1 cm-2 and detection limit of 1 nM. The practicality of sensor was demonstrated by performing real sample analysis in pork, beef, and sausage which gave adequate recovery.

A novel temperature-responsive electrochemical sensing platform for reversible switch-sensitive detection of acetamidophenol

A novel facile, quick, and temperature-controlled sensor was constructed based on a polystyrene-poly-N,N-diethyl acrylamide-polystyrene (PS-PDEAM)/carboxylated multi-walled carbon nanotube (MWCNT) composite modified glass carbon electrode. The sensor achieves acetaminophen (AP) reversibility through better temperature sensitivity. PS-PDEAM shrinks when the temperature exceeds its lower critical temperature (LCST). When AP molecules pass through the modified interface, the electron transfer rate is accelerated, and the sensor is turned on. In the off state, the electrochemical response of AP cannot be detected. Under ideal experimental conditions, for composite modified films, there is a wide detection range of AP between 1.5-85.1 μM and 85.1-235.1 μM, and the limit of detection of acetaminophen is as low as 0.57 μM (S/N = 3). This method has been successfully applied to the determination of AP in tablets, and shows high stability, good reproducibility and excellent anti-interference ability. The on-off sensor opens up a wide range of possibilities for the use of temperature-sensitive polymers in electro-catalysis, sensors, and environmental pollutant monitoring.

Biochar-supported Cu nanocluster as an electrochemical ultrasensitive interface for ractopamine sensing

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Carbon confined Cu nanoclusters (CuNCs@CNFs) were fabricated for the enhanced sensing performance of ractopamine (RAC).

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The CuNCs@CNFs expressed ultrasensitivity and high selectivity in the electrochemical detection of RAC.

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A wide linear range and low LOD of RAC was obtained using CuNCs@CNFs based RAC sensor.

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The established RAC sensor was successfully used in sensitive detection of RAC in meat samples.

Electrochemical sensors actually involve an electrocatalytic process involving an efficient and selective energy conversion that is related to the morphology and size of the interface of the modified materials. Ultrasmall nanoclusters or single atoms generate a greater catalytic ability than normal nanomaterials. In this study biochar-supported Cu nanoclusters (CuNCs@CNFs) were fabricated via a carbon confinement synthesis method toward ultrasensitive electrochemical sensing of ractopamine (RAC). RAC is a β-adrenergic receptor agonist that is illegally used as a feed additive to significantly improve muscle accretion, resulting in RAC accumulation in meat-based food products. The unique structure of CuNCs@CNFs and the interconnectivity between the CuNCs and the CNFs enable the nanocomposite to significantly enhance conductivity and electrocatalytic activity. Using the CuNCs@CNFs-based sensor, RAC was determined with a high sensitivity of 1641 μA μM⁻¹ cm⁻². The feasibility of detecting RAC in spiked meat samples was also carried out with satisfactory recoveries ranging from 91.39 % to 94.58 %.

Facile synthesis of surface functionalized Pd2+@P-CDP/COFs for highly sensitive detection of norfloxacin drug based on the host-guest interaction

In this work, β-cyclodextrin porous polymers (P-CDPs) functionalized novel covalent organic frameworks (P-CDPs/COFs) were synthesized by a simple and facile method. After combined with Pd²⁺ via electrostatic interaction, the Pd²⁺@P-CDPs/COFs nanocomposites were prepared and utilized as novel electrode materials to fabricate the non-enzyme electrochemical sensors for high-sensitivity detection of Norfloxacin (NF). Due to the host-guest recognition, excellent adsorption performance and catalytic performance of Pd²⁺@P-CDPs/COFs, the prepared sensor exhibited excellent electrochemical performance for detecting NF under the optimum conditions, which showed two linear ranges of 0.08-7.0 μM and 7.0-100.0 μM with a low detection limit of 0.031 μM (S/N = 3). Additionally, the obtained sensor has also been successfully applied to measure NF with satisfactory results in the real medicinal samples of NF eye-drops. Our findings paved the way for the development of COFs-based sensing platform in drug analysis and testing for human health, food security and the quality control of drugs.

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.

d-Penicillamine functionalized dendritic fibrous nanosilica (DFNS-DPA): synthesise and its application as an innovative advanced nanomaterial towards sensitive quantification of ractopamine

During the twentieth century, ractopamine (RAC) as one of the important and frequently used feed additives and doping agents has attracted considerable attention in the animal breeding industry and sports competitions.

Two-dimensional binary nanosheets (Bi2Te3@g-C3N4): Application toward the electrochemical detection of food toxic chemical

Bismuth telluride is considered as an efficient and super-active electrocatalyst in the sector of electrochemical application. Herein, we prepared binary nanosheets (Bi₂Te₃) through simple solvothermal and hydrothermal method. Furthermore, to enhance the electrocatalytic activity, graphitic carbon nitrides nanosheets (g-C₃N₄) were used to prepare the composition of Bi₂Te₃/g-C₃N₄ binary nanosheets (BNs) with help of hydrothermal energy. Moreover, Bi₂Te₃/g-C₃N₄ hybrid was characterized by various techniques (XRD, XPS, SEM, TEM, EDS and EIS analysis). The electrochemical performance of Bi₂Te₃/g-C₃N₄ BNs modified GCEs were analyzed by electrochemical technique (DPV, EIS and CV methods). As modified the Bi₂Te₃/g-C₃N₄ BNs modified electrode exhibits excellent electrochemical activity towards food toxic ractopamine (RAC) with high-sensitive and nano-molar detection limit (LOD). Besides, the practical ability was analyzed to detect the RAC in meat samples using Bi₂Te₃/g-C₃N₄ BNs modified GCE.

AgNPs/QDs@GQDs nanocomposites developed as an ultrasensitive impedimetric aptasensor for ractopamine detection

Developing easy-to-use and miniaturized sensors for in-field monitoring of targets which is related to human health is necessary. Ractopamine (RAC) is a feed additive with serious side effects that is forbidden in many countries. This study reports the fabrication of an impedimetric aptasensor for ultrasensitive and selective detection of the RAC in human biological fluids. Accordingly, an efficient nanocomposites was synthesized by a beneficial combination of graphene quantum dots (GQDs), quantum dots (QDs) and silver nanoparticles (AgNPs) for modifying a glassy carbon electrode (GCE). This nanocomposite is promising to present a synergistic effect in the increase of the active surface area of the modified electrode to more load the biocapture of the target. Next, the RAC-binding aptamer (Apt) was attached to the AgNPs/QDs@GQDs/GCE surface and a sensitive layer for the RAC detection was embedded. A RAC-Apt complex was formed upon adding the RAC and the changes of the electrochemical behavior were studied by some electrochemical techniques such as electrochemical impedance spectroscopy (EIS). Under optimal conditions, the charge transfer resistance (R_ct) value was increased linearly with increasing of the RAC concentrations in the range of 1 fM to 901.4 nM. Limit of detection (LOD) was calculated to be 330 aM which is superior by other reported electrochemical methods in the RAC sensing. The applicability of the aptasensor was tested in human urine and blood serum as the real samples and satisfactory results of specificity were achieved. It seems that the proposed strategy not only provides a new ultrasensitive strategy for RAC detection but also expands the application of the sensing interface to develop other aptasensors by changing the Apt sequence.

Sonochemical synthesis of perovskite-type barium titanate nanoparticles decorated on reduced graphene oxide nanosheets as an effective electrode material for the rapid determination of ractopamine in meat samples

A simple and facile ultrasound based sonochemical method to incorporate Perovskite-type barium titanate (BaTiO₃) nanoparticles inside the layered and reduced graphene oxide sheets (rGOs) is reported. BaTiO₃@rGOs nanocomposite was characterized by FESEM, HRTEM, EDX, mapping, XRD, XPS and EIS. The results show that the decoration and also incorporation of BaTiO₃ nanoparticles in the multi-layered and ultrasound reduced graphene oxide matrix. Non-enzymatic and differential pulse voltammetric sensor of ractopamine (food toxic) based on the BaTiO₃@rGOs nanocomposite modified screen printed carbon electrode is developed. Compared with the original BaTiO₃/SPCE and rGOs/SPCE, the BaTiO₃@rGOs/SPCE displays excellent current response towards ractopamine and gives linearity in the range of 0.01-527.19 µM ractopamine in neutral phosphate buffer (pH 7.0). The BaTiO₃@rGOs nanocomposite modified sensor also exhibits valuable ability of anti-interference to electroactive analytes. Furthermore, the as-prepared BaTiO₃ NPs@rGOs/SPCE has been applied to the determination of ractopamine in pork and chicken samples.

In situ Preparation of HNbMoO6/C Nanocomposite for Sensitive Detection of Clenbuterol

In this paper, we synthesized HNbMoO₆/C composite through the calcination of octylamine-intercalated HNbMoO₆ precursor. The resulting HNbMoO₆/C composite showed some new phases of MoO₂, MoO₃, NbO₂, Nb₂O₅, and carbon, which was fully confirmed via powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and X-ray photoelectron spectroscopy (XPS) technologies. Besides, the HNbMoO₆/C hybrid was coated on glass carbon electrode to construct an electrochemical sensor for sensitive determination of clenbuterol. The electrochemical behaviors of clenbuterol on the prepared electrode were tested by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) analysis. The results showed that the intercalated carbon can act as active sites to accelerate electron transfer. In addition, more exposed surface areas of the HNbMoO₆/C composite will facilitate the electrolyte to permeate. The oxidation peak current of clenbuterol was linearly related to its concentration in the range of 1.04 × 10^-5 to 7.51 × 10^-4 mol L^-1, and the determination limit was calculated to be 3.03 × 10^-6 mol L^-1 (S/N = 3). This sensor exhibits excellent stability, reproducibility, specificity, and good recoveries when applied to monitor clenbuterol in real samples.

Colorimetric detection of the β-agonist ractopamine in animal feed, tissue and urine samples using gold-silver alloy nanoparticles modified with sulfanilic acid

A highly sensitive, selective and simple method was proposed for colorimetric detection of ractopamine on the basis of the interaction between ractopamine and sulfanilic acid-modified gold-silver alloy nanoparticles (AuAgNPs). The AuAgNPs were prepared by the reduction of HAuCl₄ and AgNO₃ with sodium citrate in aqueous medium and further modified by sulfanilic acid. The interaction of ractopamine with sulfanilic acid induced rapid aggregation of sulfanilic acid-modified AuAgNPs along with an optical colour change, leading to precise quantification which could be detected by absorptiometry. Under the optimum conditions, the absorbance ratio (A₆₀₀/A₄₃₅) of sulfanilic acid-modified AuAgNPs exhibited a linear relationship with the concentration of ractopamine in the range of 4.5-31.6 ng/mL. The detection limit of ractopamine was 1.5 ng/mL. The established novel colorimetric detection method showed high selectivity towards ractopamine. The method was successfully applied to detect ractopamine in spiked pork, swine feed and swine urine samples with excellent recoveries from 94.4% to 112.5%. These results demonstrated that the proposed new method has a good potential for practical applications.

Simultaneous determination of β-agonists on hexagonal boron nitride nanosheets/multi-walled carbon nanotubes nanocomposite modified glassy carbon electrode

β-Agonists are illegally consumed in various products such as food and animal and effect the nutrition distribution owing to change of body fat. In addition, they result in acute poisoning and several symptoms such as muscular tremors and nervousness. A new electrochemical approach based on two-dimensional hexagonal boron nitride (2D-hBN) nanosheets decorated functionalized multi-walled carbon nanotubes (f-MWCNTs) was presented for simultaneous determination of β-agonists such as phenylethanolamine A (PEA), clenbuterol (CLE), ractopamine (RAC) and salbutamol (SAL) in urine samples. X-ray diffraction (XRD) method, Raman spectroscopy, scanning electron microscope (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used characterizations of nanomaterials. After that, 2D-hBN/f-MWCNTs nanocomposite modified glassy carbon electrode (GCE) was prepared for simultaneous determination of β-agonists. 1.0 × 10^-12-1.0 × 10^-8 M and 1.0 × 10^-13 M were founded as the linearity range and the detection limit (LOD) for PEA, CLE, RAC and SAL. Finally, the prepared electrochemical sensor was used for urine sample analysis in presence of ascorbic acid (AA) and uric acid (UA).

Cross-linked chitosan/thiolated graphene quantum dots as a biocompatible polysaccharide towards aptamer immobilization

Chitosan has a number of commercial and possible biomedical uses. Chitosan as a polysaccharide is a bioactive polymer with a variety of applications due to its functional properties such as antibacterial activity, non-toxicity, ease of modification, and biodegradability. In this work, cross-linked chitosan/thiolated graphene quantum dot as a biocompatible polysaccharide was modified by gold nanoparticle and used for immobilization of ractopamine (RAC) aptamer. A highly specific DNA-aptamer (5'-SH-AAAAAGTGCGGGC-3'), selected to RAC was immobilized onto thiolated graphene quantum dots (GQDs)-chitosan (CS) nanocomposite modified by gold nanostructures (Au NSs) and used for quantification of RAC. Different shapes of gold nanostructures with various sizes from zero-dimensional nanoparticles to spherical structures were prepared by one-step template-assistant green electrodeposition method. Fully electrochemical methodology was used to prepare a new transducer on a glassy carbon surface which provided a high surface area to immobilize a high amount of the aptamer. Therefore, a label free electrochemical (EC) apta-assay for ultrasensitive detection of RAC was developed. A special immobilization media consisting of Au NSs/GQDs-CS/Cysteamine (CysA) was utilized to improve conductivity and performance of the biosensor. The RAC aptamer was attached on the Au NSs of the composite membrane via AuS bond. The fabrication process of the EC aptamer based assay was characterized by some electrochemical techniques. The peak currents obtained by differential pulse voltammetry decreased linearly with the increasing of RAC concentrations and the apta-assay responds approximately over a wide dynamic range of RAC concentration from 0.0044 fM to 19.55 μM. The low limit of quantification was 0.0044 fM.

Ag–SnO2 nano-heterojunction–reduced graphene oxide by a stepwise photocatalyzed approach and its application in ractopamine determination

Stepwise reduction process for SnO₂–AgNPs–reduced graphene oxide under UV irradiation and its energy-band structure.

Photoelectrocatalytic analysis and electrocatalytic determination of hydroquinone by using a Cu2O-reduced graphene oxide nanocomposite modified rotating ring-disk electrode

Reduced graphene oxide (rGO)-based Cu2O nanocomposites were prepared by a facile one-pot reaction process. The surface morphology, structure and chemical composition of Cu2O-rGO nanocomposites were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The Cu2O-rGO modified Pt rotating ring-disk electrode (RRDE) was successfully fabricated for the photoelectrocatalytic analysis of hydroquinone (HQ). The photoelectrochemical behaviors of HQ were investigated by the hydrodynamic differential pulse voltammetry technique, using the Cu2O-rGO modified Pt RRDE as the working electrode. The effects of pH values, rotation rates, illumination time and applied bias potential have been discussed. The possible electroactive intermediate product, namely hydroxyhydroquinone, was obtained through the photoelectrocatalytic degradation of HQ on the Cu2O-rGO modified Pt disk electrode, which was compulsively transported and could only be detected at the bare Pt ring electrode at around +0.02 V with an oxidation signal. We found that the peak current at +0.02 V had a good linear relationship with the HQ concentration in the range from 5.0 × 10(-6) to 1.0 × 10(-3) M, with a low limit of detection and excellent reproducibility. The present work has demonstrated that Cu2O-rGO nanocomposites have enhanced photoelectrocatalytic ability for the degradation of organic pollutants and this modified RRDE technique can be potentially applied for the in situ determination of organic pollutants.

Preparation of ractopamine-tetraphenylborate complexed nanoparticles used as sensors to rapidly determine ractopamine residues in pork

In this work, we reported a simple, fast, and sensitive determination of ractopamine (RAC) residues in pork by using novel ractopamine-tetraphenylborate complexed nanoparticles (RT NPs) as sensors. The prepared RT NPs exhibited a fast response time of 10 s, a wide linear range from 0.1 to 1.0 × 10(-7) mol/L, and a very low detection limit of 7.4 × 10(-8) mol/L. The prepared sensor also presents a high selectivity for ractopamine under different pH conditions ranged from 2.85 to 7.18. These results reveal that the fabricated RT NPs can be used as efficient electrochemical sensors to determine ractopamine in animal productions.

A novel electrochemical sensor for the analysis of β-agonists: the poly(acid chrome blue K)/graphene oxide-nafion/glassy carbon electrode

A novel modified electrode was constructed by the electro-polymerization of 4,5-dihydroxy-3-[(2-hydroxy-5-sulfophenyl)azo]-2,7-naphthalenedisulfonic acid trisodium salt (acid chrome blue K (ACBK)) at a graphene oxide (GO)-nafion modified glassy carbon electrode (GCE). The characterization of an electrochemically synthesized poly-ACBK/GO-nafion film was investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), atomic force microscopy (AFM) and scanning electron microscopy (SEM) techniques, and the results were interpreted and compared at each stage of the electrode construction. Electrochemical oxidation of eight β-agonists - clenbuterol, salbutamol, terbutaline, ractopamine, dopamine, dobutamine, adrenaline, and isoprenaline, was investigated by CV at the different electrodes. At the poly-ACBK/GO-nafion/GCE, the linear sweep voltammetry peak currents of the eight β-agonists increased linearly with their concentrations in the range of 1.0-36.0 ng mL(-1), respectively, and their corresponding limits of detection (LODs) were within the 0.58-1.46 ng mL(-1) range. This electrode showed satisfactory reproducibility and stability, and was used successfully for the quantitative analysis of clenbuterol in pork samples.

Colorimetric detection of ractopamine and salbutamol using gold nanoparticles functionalized with melamine as a probe

A highly selective and sensitive method is developed for colorimetric detection of ractopamine and salbutamol using gold nanoparticles (AuNPs) functionalized with melamine (MA), respectively. The presence of these β-agonists induces the aggregation of gold nanoparticles through hydrogen-bonding interaction that was accompanied by a distinct change in color and optical properties, which could be monitored by a UV-vis spectrophotometer or even naked eyes. This process caused a significant decrease in the absorbance ratio (A670 nm/A520 nm) of melamine-gold nanoparticles (MA-AuNPs), and the color changed from wine red to blue. The systems exhibited a wide liner range, from 1×10(-10)M to 5×10(-7)mol/L with a correlation coefficient of 0.995 for ractopamine, and 1×10(-10)M to 1×10(-5)mol/L with a correlation coefficient of 0.996 for salbutamol, with measuring the absorbance ratio (A670 nm/A520 nm). The detection limit of these β-agonists is as low as 1×10(-11)mol/L. Particularly, the developed method has been applied to the analysis of real swine feed samples and has achieved satisfactory results.