Highly sensitive determination of tetracycline in chicken meat and eggs using AuNP/ MWCNT-modified glassy carbon electrodes

A direct electrochemical sensor based on covalent organic frameworks/platinum nanoparticles for the detection of ofloxacin in water

A direct electrochemical sensor based on covalent organic frameworks (COFs)/platinum nanoparticles (PtNPs) composite was fabricated for the detection of ofloxacin (OFX) in water. Firstly, the COF material was synthesized via the condensation reaction of 1,3,5-tris(4-aminophenyl)benzene (TAPB) with terephthalaldehyde (TPA) and integrated with PtNPs by in situ reduction. Then, TAPB-TPA-COFs/PtNPs composite was loaded onto the surface of the glassy carbon electrode (GCE) by drip coating to construct the working electrode (TAPB-TPA-COFs/PtNPs/GCE). The electrochemical performance of TAPB-TPA-COFs/PtNPs/GCE showed a significant improvement compared with that of TAPB-TPA-COFs/GCE, leading to a 3.2-fold increase in the electrochemical signal for 0.01 mM OFX. Under optimal conditions, the TAPB-TPA-COFs/PtNPs/GCE exhibited a wide linear range of 9.901 × 10-3-1.406 µM and 2.024-15.19 µM with a detection limit of 2.184 × 10-3 µM. The TAPB-TPA-COFs/PtNPs/GCE-based electrochemical sensor with excellent performance provides great potential for the rapid and trace detection of residual OFX.

Rapid and sensitive detection of tetracycline residue in food samples using Cr(III)-MOF fluorescent sensor

As tetracycline antibiotics were used in the poultry sector, their residue in edible animal products may adversely affect food safety and human health. The development of selective and sensitive tetracycline sensors has garnered a lot of interest due to the complexity of food samples. Therefore, a fluorescent sensing probe based on chromium(III)-metal-organic framework was developed for the rapid detection of tetracycline. After the addition of tetracycline, blue emission at λem 410 nm was effectively quenched by the interaction between TC and Cr(III)-metal-organic framework material. Under optimized conditions (sensor concentration: 30 mg/L and pH: 10.0), the sensing probe showed a fast response time (1 min), and low detection limit (0.78 ng/mL) with a linear range (5-45 ng/mL). Interestingly, the Cr(III)-metal-organic framework was successfully applied to quantity tetracycline residue in chicken meat and egg samples with recoveries of 95.17-06.93%. To deduce, our work can provide a new strategy for the direct detection of tetracycline in food samples.

Preparation of an electrochemical sensor utilizing graphene-like biochar for the detection of tetracycline

Tetracycline (TC), which is ubiquitous in the aquatic environment, can cause ecological imbalance and adversely affect human health. Therefore, a quick, inexpensive, and easy method for the detection of TC in water systems is highly desirable. This study reports the development of a novel electrochemical sensor from waste peanut shell for the quick detection of TC in water. Raman and TEM lattice mapping analyses confirmed the successful preparation of graphene -like biochar from waste peanut shells (PSs) via hydrothermal and pyrolysis processes. An electrochemical sensor, PS@glassy carbon electrode (PS@GCE), was then developed by coating the prepared graphene-like biochar on the surface of a glass electrode to enhance its conductivity. The feasibility of using this sensor for the detection of TC in the aqueous system was investigated. The PS@GCE sensor exhibited excellent sensitivity with a low detection limit of 3.6 × 10--9 nM and a linear range of 10-10-102 μM. These results were attributed to the large specific surface area and high conductivity, of the PS biochar. The stability of the PS@GCE sensor was also investigated in the presence of TC (10-4 M) and interfering species (10-2 M) and recovery rates in the range of 86.4%-116.0% were achieved, thus indicating the absence of an interference range of range of 84.3%-98.2% with relative standard deviation lower than 6% were achieved upon the detection of TC in natural water samples using the designed sensor, thus confirming the superior repeatability of the PS@GCE sensor. Consequently, the designed electrode has a high potential for application in the detection of TC in natural aqueous systems.

Lab-made 3D-printed electrochemical sensors for tetracycline determination

Antibiotics such as tetracycline (TC) are widely prescribed to treat humans or dairy animals. Therefore, it is important to establish affordable devices in laboratories with minimal infrastructure. 3D printing has proven to be a powerful and cost-effective tool that revolutionizes many applications in electrochemical sensing. In this work, we employ a conductive filament based on graphite (Gr) and polylactic acid (PLA) (40:60; w/w; synthesized in our lab) to manufacture 3D-printed electrodes. This electrode was used "as printed" and coupled to batch injection analysis with amperometric detection (BIA-AD) for TC sensing. Preliminary studies by cyclic voltammetry and differential pulse voltammetry revealed a mass transport governed by adsorption of the species and consequent fouling of the redox products on the 3D printed surface. Thus, a simple strategy (solution stirring and application of successive potentials, +0.95 V followed by +1.2 V) was associated with the BIA-AD system to solve this effect. The proposed electrode showed analytical performance comparable to costly conventional electrodes with linear response ranging from 0.5 to 50 μmol L^-1 and a detection limit of 0.19 μmol L^-1. Additionally, the developed method was applied to pharmaceutical, tap water, and milk samples, which required minimal sample preparation (simple dilution). Recovery values of 92-117% were obtained for tap water and milk samples, while the content found of TC in the capsule was close to the value reported by the manufacturer. These results indicate the feasibility of the method for routine analysis involving environmental, pharmaceutical, and food samples.

Dual mode detection and sunlight-driven photocatalytic degradation of tetracycline with tailor-made N-doped carbon dots

Carbon dots have emerged as one of the most promising materials with various potential applications derived from their unique photophysical and chemical properties. The present work investigates the electrochemical and photochemical properties of one-pot synthesized carbon dots for environmental sustainability. Facile microwave-assisted pyrolysis of urea and glucose yielded nitrogen doped carbon dots (N-doped carbon dots) with blue fluorescence and a quantum yield of 14.9%. As synthesized N- doped carbon dot had intense fluorescence, stability, water solubility, and biocompatibility. In the sensing studies, N-doped carbon dots appeared as a dual sensor for drug tetracycline with excellent sensitivity and selectivity. Beyond sense, the carbon dots have the potential to act as a photocatalyst for the degradation of tetracycline. Further, N-doped carbon dot could bring exhaustive degradation of tetracycline (>95%) within 10 min in the absence of any additives. This is the first time report on the utilization of raw non-metal doped carbon dots as a photocatalyst for the degradation of tetracycline.

A high-performance electrochemical sensor for sensitive detection of tetracycline based on a Zr-UiO-66/MWCNTs/AuNPs composite electrode

Herein, a high-performance electrochemical sensor was constructed based on a metal-organic framework (Zr-UiO-66)/multi-carbon nanotubes/gold nanoparticles (Zr-UiO-66/MWCNTs/AuNPs) composite modified glassy carbon electrode for sensitive determination of tetracycline. The morphology, structure, and performance of Zr-UiO-66/MWCNTs/AuNPs were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), and electrochemical techniques. The Zr-UiO-66/MWCNTs/AuNPs nanohybrids exhibited excellent electrocatalytic activity towards the oxidation of tetracycline, mainly because of the synergistic effect of the MOFs, MWCNTs, and gold nanoparticles. The electrochemical kinetics and catalytical mechanism of tetracycline were demonstrated, proving that tetracycline's electrocatalytic oxidation reaction was an absorption-controlled two-step process involving the transfer of two protons and two electrons, respectively. Furthermore, a simple and facile method was used to achieve the regeneration of the absorbed saturated electrode. A low concentration of tetracycline was detected by amperometry with the linear ranges of 5 × 10^-7 to 2.25 × 10^-4 mol L^-1 (R² = 0.9941), the sensitivity was 45.4 mA L mol^-1, and the limit of detection was as low as 1.67 × 10^-7 mol L^-1 (S/N = 3). In addition, the composite electrode demonstrated high selectivity (interference deviation of ± 5%), satisfactory reproductivity (RSD of 5.31%), and long-term stability (easy regeneration) and was successfully applied in the analysis of tetracycline antibiotics in actual samples. Thus, the proposed electrode provides a promising and prospective MOFs-based sensing platform for the detection of tetracyclines in the environment.

Graphene-based electrochemical sensors for antibiotic detection in water, food and soil: A scientometric analysis in CiteSpace (2011-2021)

The residues of antibiotics in the environment pose a potential health hazard, so highly sensitive detection of antibiotics has always appealed to analytical chemists. With the widespread use of new low-dimensional materials, graphene-modified electrochemical sensors have emerged as an excellent candidate for highly sensitive detection of antibiotics. Graphene, its derivatives and its composites have been used in this field of exploration in the last decade. In this review, we have not only described the field using traditional summaries, but also used bibliometrics to quantify the development of the field. The literature between 2011 and 2021 was included in the analysis. Also, the sensing performance and detection targets of different sensors were compared. We were able to trace not only the flow of research themes, but also the future areas of development. Graphene is a material that has a high potential to be used on a large scale in the preparation of electrochemical sensors. How to design a sensor with selectivity and low cost is the key to bring this material from the laboratory to practical applications.

Electrochemically reduced graphene oxide/Cu-MOF/Pt nanoparticles composites as a high-performance sensing platform for sensitive detection of tetracycline

A promising sensing platform was constructed based on an electrochemically reduced graphene oxide (ErGO)/copper metal-organic framework (Cu-MOF)/platinum nanoparticles (ErGO/Cu-MOF/PtNPs) modified glassy carbon electrode for the detection of tetracycline. The ErGO/Cu-MOF/PtNPs composite electrode possessed an excellent electrochemical performance to tetracycline detection mainly due to the synergistic effect of ErGO, Cu-MOF and PtNPs. The electrochemical kinetics and catalytical mechanism of tetracycline were systematically studied, showing that tetracycline's electrocatalytic oxidation reaction was an absorption-controlled two-step process involving two electrons and one proton transfer, respectively. Low concentration of tetracycline was detected by amperometry with the a linear range of 1 ~ 200 μM (R² = 0.9900) and a detection limit of 0.03 μM (S/R = 3). The proposed sensor was successfully applied to the detection of tetracycline in the real water samples with recoveries of 93.5% ~ 106%, and relative standard deviations (RSD) of 4.65% ~ 5.21% (n = 3). Furthermore, acceptable stability, repeatability and reproducibility were verified for continuous determination of tetracycline under optimized conditions. The ErGO/Cu-MOF/PtNPs composite electrode also demonstrated better anti-interference performance compared to other types of antibiotics than that of similar structural tetracyclines. Therefore, the proposed ErGO/Cu-MOF/PtNPs composites might provide a potential sensing platform for detecting analogous tetracyclines or total tetracyclines in the environment.

Residues of tetracyclines and β-lactams antibiotics induce carbonylation of chicken breast

Background: Worldwide, chicken meat is widely consumed due to its low cost, high nutritional value and non-interference with religious or cultural beliefs. However, during animal husbandry chickens are exposed to many chemical substances, including tetracyclines and β-lactams, which are used to prevent and cure several infections. Some residues of these compounds may bioaccumulate and be present in chicken meat after slaughtering, promoting oxidative reactions. Methods: In order to evaluate in vitro carbonylation induced by tetracyclines and β-lactams residues, a proteomic approach was used. For this, chicken muscle was individually contaminated with tetracyclines (tetracycline, chlortetracycline, oxytetracycline, and doxycycline) and β-lactams (ampicillin, benzathine penicillin, dicloxacillin and oxacillin) at 0.5, 1.0 and 1.5 times their maximum residue level (MRL). Then, sarcoplasmic, myofibrillar and insoluble proteins were extracted and their content were measured using the Bradford method. Protein carbonylation was measured using the 2,4-Dinitrophenylhydrazine alkaline method. Results: Residues of tetracyclines and β-lactams induced in vitro carbonylation on sarcoplasmic, myofibrillar and insoluble proteins even at 0.5MRL concentrations ( p<0.05). When comparing the carbonylation induced by both antibiotics no differences were found ( p>0.05). Variables such as the partition coefficient (log P) and the concentration of these antibiotics showed a high correlation with the oxidative capacity of tetracyclines and β-lactams on chicken breast proteins. Conclusions: This study shows that the presence of tetracyclines and β-lactams residues at MRLs concentrations promotes in vitro carbonylation on chicken breast proteins. Our results provide important insights about the impact of antibiotics on the integrity of meat proteins intended for human consumption.

Advances and perspectives of aptasensors for the detection of tetracyclines: A class of model compounds of food analysis

The residual tetracyclines in food are frequently applied as the model compounds to develop aptasensors. Until now, more than 100 advanced aptasensors towards tetracyclines have been developed and published in English. This review summarizes and discusses comprehensively these advanced aptasensors, in terms of the principle designs, applied frontier transducers/materials, working performance, and advantages/disadvantages. The aptasensors are classified according to the inherent transduction techniques, i.e., optics, optics-electricity, optics-mass, and electricity-mass. Moreover, the present challenges such as the limited specificity and limited affinity of the aptamers, the future prospects and trends such as further combination with other advanced materials and technologies, and the urgent need of expanding the practical application were discussed and prospected. We hope this review can serve as a powerful tool for both tracing the development progresses of aptasensors and providing adequate references for further development of aptasensing methods for food-related analytes.

Ilies) S, Orha C, Manea F. Graphene Oxide Electroreduced onto Boron-Doped Diamond and Electrodecorated with Silver (Ag/GO/BDD) Electrode for Tetracycline Detection in Aqueous Solution

A new electrochemical sensor designed by modifying the commercial boron-doped diamond (BDD) electrode with graphene oxide (GO) reduced electrochemically and further electrodecorated with silver (Ag), named the Ag/GO/BDD electrode, was selected among a series of the BDD, GOelectroreduced onto BDD (GO/BDD) and silver electrodeposited onto BDD (Ag/BDD) electrodes for the detection of tetracycline (TC) in aqueous solution. The best results regarding the sensitivity of 46.6 µA·µM-1·cm-2 and the lowest limit of detection of 5 nM was achieved using square-wave voltammetry (SWV) operated at the step potential of 5 mV, modulation amplitude of 200 mV and the frequency of 10 Hz in alkaline medium. The application of the alkaline supporting electrolyte-based procedure is limited for water monitoring due to the presence of chloride that interferes with TC detection; however, it can be applied for quantitative determination of pharmaceutical formulations. 0.1 M Na2SO4 supporting electrolyte eliminated chloride interference and can be used for the application of Ag/GO/BDD in practical detection of TC in water.

Determination of antibiotics in meat samples using analytical methodologies: A review

Antibiotics are widely used to prevent or treat some diseases in human and veterinary medicine and also as animal growth promoters. The presence of these compounds in foods derived from food-producing animals can be a risk for human health. Consequently, regulatory agencies have set maximum residue limits for antibiotics in food samples. Therefore, the development of novel methodologies for its determination in food samples is required. Specifically, the analysis and quantification of these substances in meat tissues is a challenge for the analytical chemistry research community. This is due to the complexity of the matrix and the low detection limits required by the regulatory agencies. In this sense, a comprehensive review on the development of new sample preparation treatments involving extraction, cleanup, and enrichment steps of antibiotics in meat samples in combination with sensitive and sophisticated determination techniques that have been carry out in the last years is necessary. Therefore, the aim of this work is to summarize the published methodologies for the determination of antibiotics from 2016 until the beginning of the second semester of 2020. The first part of this review includes an introduction about antibiotic families, followed by sample preparation and determination techniques applied to the different families. Finally, a detailed discussion of the current trends and the future possible perspectives in this field are also included.

Adsorptive stripping voltammetric determination of Tetracycline in pharmaceutical capsule formulation using Poly(Malachite green) modified glassy carbon electrode

A selective and sensitive electrochemical method based on glassy carbon electrode modified with poly(malachite green) was developed for determination of tetracycline in pharmaceutical capsule formulation. Cyclic voltammetry and electrochemical impedance spectroscopy using [Fe(CN)6]3-/4- as a probe were used to characterize the potentiodynamiclly deposited poly(malachite green) on the surface of glassy carbon electrode. In contrast to the unmodified glassy carbon electrode, the fabricated poly(malachite green) modified glassy carbon electrode showed catalytic property towards two steps irreversible oxidation of tetracycline. Better correlation of the oxidative peak current with the scan rate than with the square root of scan rate supported by slope of 0.60 for log(current) versus log(scan rate) indicated that the oxidation reaction of tetracycline at the modified electrode was predominantly controlled by electron exchange step at the solution polymer interface. Under optimized solution pH, and accumulation parameters, the square wave adsorptive anodic striping peak current response of the modified electrode showed linear dependence on concentration of tetracycline in the range 5-100 μM with determination coefficient, method detection limit, and quantification limit of 0.99588, 1.6 μM, and 5.3 μM, respectively. The tetracycline content of a capsule sample claimed to have 250 mg/capsule was found to be 250.53 mg/capsule with 0.21% deviation. Excellent spike recovery result of 99.80%, and 98.49-99.78% recovery of tetracycline in capsule sample in the presence of 50-200% of UA, AA, and ampicillin validated the applicability of the method for determination of tetracycline in real samples with complex matrix like capsule formulations.