Chloramphenicol In Milk Samples Research Articles

Highly sensitive and label-free immunoassay of chloramphenicol based on poly-adenine-mediated spherical nucleic acid and hybridization chain reaction amplification

In this paper, a label-free fluorescent immunoassay for chloramphenicol was established based on a DNA-assisted signal amplification strategy. The poly-adenine mediated spherical nucleic acid was firstly employed as the substrate of antibody to construct the immunonanoprobes. Enzyme-free signal amplification techniques, hybridization chain reaction and strand displacement reaction, were utilized to develop the dual amplification strategy. The output signal was expressed through the use of G-quadruplex to achieve label free fluorescence changes. Under optimized conditions, the detection limit of this method was reduced to 0.0044 ng/L. The method exhibited a high accuracy to the detection of chloramphenicol in milk samples with a recovery rate from 94.5% to 118.1%. However, the limitations of this method probably lied in the overlong detection time and the possible interference from other compounds present in food samples. The developed label-free fluorescent immunoassay could provide an innovative view for the reliable and ultrasensitive detection of chloramphenicol, which is conducive to the food safety.

A sensitive enzyme-free electrochemical sensor based on ZnWO4/γ-Fe2O3 magnetic molecularly imprinted polymer for specific recognition and determination of Chloramphenicol

A chloramphenicol (CAP) electrochemical sensor based on zinc tungstate and magnetic hematite (ZnWO4/γ-Fe2O3) magnetic molecularly imprinted polymer (ZnWO4/γ-Fe2O3/MIP) is proposed. First, ZnWO4, γ-Fe2O3 nanomaterials were synthesized by one-step hydrothermal method, and then ZnWO4, magnetic nanoparticles were combined with molecularly imprinted polymers, that is, ZnWO4/γ-Fe2O3 was coated with a molecularly imprinted (MIP) shells by precipitation polymerization method to prepare magnetic molecularly imprinted nanomaterials, and then modified on glassy carbon electrodes to construct an electrochemical sensor for the determining of CAP. The results show that under the optimal conditions, the ZnWO4/γ-Fe2O3/MIP (MMIP) modified electrode has a stronger CAP detection reduction peak current than the one-component electrode, and exhibits better electrocatalytic activity, which is an excellent electrochemically modified electrode. Compared to magnetic non-molecular imprint sensors (MNIP), MMIP sensors have higher detection efficiency. The linear range of ZnWO4/γ-Fe2O3/MIP/GCE for the detection of CAP was 0.12 ∼ 1224 μM, and the detection limit was 0.034 μM, showing excellent stability and reproducibility, and good selectivity in the presence of different interferences. ZnWO4/γ-Fe2O3/MIP/GCE was applied to the detection of CAP in milk samples with satisfactory results.

The electrochemical performances of porous niobium pentoxide with multi-walled carbon nanotubes nanocomposite incorporated with glassy carbon electrode for the sensing of chloramphenicol

Chloramphenicol (CPL), a developing emergence of detection, was selected after sorting out many harmful hazards associated with the nominal dose of medications. Therefore, the detection of CPL is needed to defend the ecosystem. Consequently, this work provides exceptional scrutinization of the CPL reduction process utilizing the electrochemical method by the constructed nanomaterial which is hydrothermally prepared metal oxide such as Niobium Pentoxide (Nb2O5) with the Multi-Walled Carbon Nanotube (MWCNT), which are prepared as a nanocomposite of MWCNT/Nb2O5. Thus, MWCNT/Nb2O5 nanocomposite was drop cast on the surface of a glassy carbon electrode to construct MWCNT/Nb2O5/GCE electrode utilized for the detection of CPL. The MWCNT/Nb2O5/GCE composite was characterized by field emission scanning electron microscopy (FESEM), Brunauer-Emmette-Teller studies (BET), high-resolution transmission electron microscope (HR-TEM), energy dispersion X-ray spectroscopy (EDAX), X-ray photon spectroscopy (XPS) and X-ray diffraction analysis (XRD). Furthermore, the electrochemical performance of the prepared electrode was identified by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and differential pulse voltammetry (DPV) studies, respectively. The electrochemical investigations of the MWCNT/Nb2O5/GCE were conducted at −1.0 V to −0.2 V. The limit of detection (LOD) of the CPL was obtained with very low concentrations of 0.1 μM with a high sensitivity of 0.364 μA μM−1 cm−2 and a wide linear range (0.01–240 μM). Finally, the MWCNT/Nb2O5/GCE electrode performed acceptable repeatability, reproducibility, and stability performance. The prepared MWCNT/Nb2O5/GCE electrodes were utilized for the detection of CPL in milk samples and honey samples with acceptable recoveries.

Polydopamine- and MOFs-based molecularly imprinted microfiltration membranes in syringe filter for selective capture of thiamphenicol, florfenicol and chloramphenicol in milk samples

In this study, molecularly imprinted microfiltration membranes (MIMFMs) based on polydopamine and metal–organic framework were innovatively proposed, and successfully prepared for capturing thiamphenicol, florfenicol and chloramphenicol from milk samples through syringe filter device. The provision of PDA and coupling of MOF particles enabled the filter membranes to have great permeability and binding capacity. Cleverly, hydrophilicity and heightened rebinding selectivity (IF = 2.42) of filter membranes was provided using two functional monomers (methacrylate and acrylamide), and microfiltration-grade composite membranes were generated by adjusting the imprinting polymerization time. The combination of the selective filter membranes and the syringe filter devices can effectively simplify the operation process, minimize the extraction time and reduce the tested sample volume. The method was validated by coupling with ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) and obtained a good correlation (r2 > 0.99). The limit of detection (LOD) of three analytes was 0.0800–0.6583 µg kg−1 and the mean recovery ranged from 85.5% to 91.2% within relative standard deviations (RSDs) less than 8.2%. Finally, an effective MIMFMs-UHPLC-MS/MS method was established for the recognition and detection of three amphenicol antibiotics in milk samples. The MIMFMs filtration technique offered in this work provides valuable science references and potential application prospects for complicated sample pretreatment.

Flexible SERS sensor using AuNTs-assembled PDMS film coupled chemometric algorithms for rapid detection of chloramphenicol in food

The misuse of chloramphenicol (CAP) has led to the development of drug-resistant strains that pose significant threats to public health. Here, we propose a universal flexible surface-enhanced Raman spectroscopy (SERS) sensor utilizing gold nanotriangles (AuNTs) and polydimethylsiloxane (PDMS) film for rapid detection of CAP in food samples. Initially, AuNTs@PDMS with unique optical and plasmonic properties were used to collect spectra of CAP. Afterward, four chemometric algorithms were executed and compared. Accordingly, random frog-partial least squares (RF-PLS) exhibited optimum results with correlation coefficient of prediction (Rp = 0.9802) and the lowest root-mean-square error of prediction (RMSEP = 0.348 µg/mL). Furthermore, the sensor's efficacy to detect CAP in milk samples was confirmed, and the findings were compatible with the conventional HPLC approach (P > 0.05). Therefore, the proposed flexible SERS sensor could effectively be used to monitor milk quality and safety.

Fluorescent Sensing of Ciprofloxacin and Chloramphenicol in Milk Samples via Inner Filter Effect and Photoinduced Electron Transfer Based on Nanosized Rod-Shaped Eu-MOF.

Rapid, facile, and accurate detection of antibiotic residues is vital for practical applications. Herein, we designed a sensitive, visual, and rapid analytical method for sensitive detection of ciprofloxacin and chloramphenicol based on a nanosized rod-shaped Europium metal organic framework (Eu-MOF). The fluorescent Eu-MOF was firstly synthesized by a simple synthetic route at room temperature, which displays a red emission. The mechanisms of detecting ciprofloxacin and chloramphenicol were confirmed to be the inner filter effect (IFE) and photoinduced electron transfer (PET). Under the optimized experimental conditions, the detection limits of the developed method for ciprofloxacin and chloramphenicol detection were 0.0136 and 3.16 μM, respectively. Moreover, the sensor was effectively applied for quantitative determination of ciprofloxacin and chloramphenicol milk samples with satisfactory recoveries of 94.5–102% and 97–110%, respectively. This work developed a new method for rapid detection of ciprofloxacin and chloramphenicol residues. In addition, the established method has potential practical application value for on-site safety regulation on antibiotic residues in animal-derived food.

Mesoporous silica coated core-shell nanoparticles substrate for size-selective SERS detection of chloramphenicol

With the growing popularity of the non-destructive technique, surface-enhanced Raman spectroscopy (SERS) demands a highly sensitive and reproducible plasmonic nanoparticles substrate. In this study, a novel bimetallic core–shell nanoparticles (Au@Ag@mSiO2NP) substrate consisting of a gold core, silver shell, and a mesoporous silica coating was synthesized. The mesoporous coating structure was created by employing template molecules such as surfactant and their subsequent removal allowing selective screening based on the size of analyte molecules. Results showed that the plasmonic substrate could selectively enhance small molecules by preventing large macromolecules to reach the exciting zone of the substrate core, achieving the detection of chloramphenicol in milk samples with a detection limit of 6.68 × 10−8 M. Moreover, the mesoporous coating provided additional stability to the Au@Ag nanoparticles, leading to the reusability of the substrate. Thus, this work offered a simple and smart Au@Ag@mSiO2NP substrate for effective SERS detection of analytes.

Fluorescence sensing of chloramphenicol based on oxidized single-walled carbon nanohorn/silicon quantum dots- aptamers

Based on the fluorescence properties of silicon quantum dots-aptamers (SiQDs-aptamers) and the excellent quenching ability of oxidized single-walled carbon nanohorns (oxSWCNHs), a simple, fast, and efficient fluorescence-on method for the determination of chloramphenicol (CAP) was established. Single-walled carbon nanohorns (SWCNHs) are linked with carboxyl groups to generate oxSWCNHs with good dispersibility, which are added to specific SiQDs-aptamers at optimal concentrations to constitute on-off oxSWCNHs / SiQDs-aptamers fluorescence sensor. In this study, the structure of oxSWCNHs was verified, and their comprehensive properties were characterized. Finally, the detection of CAP with oxSWCNHs as a quencher was realized. Under these states, the limit of detection (LOD) of CAP was 0.6 ng/mL (3σ/S, n = 11), the recovery rate in different actual samples was 94.1%∼108.1%, and the relative standard deviation (RSD) did not exceed 6.1%, which can be accurately used for determination of CAP in milk samples.

Label free structure-switching fluorescence polarization detection of chloramphenicol with truncated aptamer

In this study, the original chloramphenicol aptamer containing 80 bases was truncated to 30 bases with high affinity by the SYBR Green I assay. It was found that the ionic strength and type affect the recognition of aptamers, especially magnesium ion played a vital role in the binding process. Furthermore, the binding performance of aptamer, including binding mode, key binding sites and conformational changes were further investigated by circular dichroism spectroscopy, UV–vis absorption spectrum and molecular docking. Based on these research data, we inferred that chloramphenicol bound to the minor groove region in the aptamer double helix. Finally, the optimized aptamer LLR10 was used to develop a novel label free fluorescence polarization assay to detect chloramphenicol within SYBR Green I as the source of fluorescence polarization signal. Under optimal conditions, the designed method showed a linear detection range of 0.1–10 nM with a detection limit of 0.06 nM. Additionally, the aptasensor exhibited a high accuracy to the detection of chloramphenicol in milk samples with a recovery rate from 93.7% to 98.4%. Therefore, the developed label free fluorescence polarization aptasensor provides a new idea for the rapid, reliable and sensitive detection of chloramphenicol, which can be applied to food safety control.

An electrochemical aptasensor based on PEI-C3N4/AuNWs for determination of chloramphenicol via exonuclease-assisted signal amplification.

Anelectrochemical aptasensor, including the polyethyleneimine-graphite-like carbon nitride/Au nanowire nanocomposite (PEI-C3N4/AuNWs) and exonuclease-assisted signal amplification strategy was constructedfor the determination of chloramphenicol (CAP). Initially, a nanocomposite with substantial electrocatalytic property was synthesized by PEI-C3N4/AuNWs. This improves the conductivity and specific surface area of the PEI-C3N4/AuNW-modified gold electrode. Next, a DNA with a complementary sequence to a CAP aptamer (cDNA) was immobilized on the PEI-C3N4/AuNW-modified electrode, followed by the CAP aptamer hybridized with cDNA. The lower signal at this time is due to the negatively charged phosphate group of the oligonucleotide and [Fe (CN)6]3-/4- electrostatically repelling each other. The presence of the CAP would cause aptamer on the electrode surface to fall off and be digested by Recjf exonuclease, which resulted in target recycling, and a significant increase in DPV signal can be observed at a potential of 0.176V (vs. Ag/AgCl). Under optimal conditions, there is a linear relationship between the peak current and the logarithm of CAP concentration in the range 100 fM-1μM, and the detection limit of this aptasensor is 2.96 fM (S/N = 3). Furthermore, the resultant aptasensor has excellent specificity, reproducibility, and long-term stability, and has been applied to the detection of CAP in milk samples. Graphical abstract The detection principle of the electrochemical aptasensor for CAP detection was based on PEI-C3N4/AuNWs and exonuclease-assistant signal amplification. It is based on the fact that PEI-C3N4/AuNWs nanocomposites on the surface of the electrode can effectively improve the performance of the aptasensor, and Recjf exonuclease initiates the target recycling process, causes signal amplification.

Application of molecularly imprinted polymers and dual-emission carbon dots hybrid for ratiometric determination of chloramphenicol in milk

Chloramphenicol (CLP) is a veterinary antibiotic that has been banned due to its severe side effects but it is still illegally used in animal husbandry. In this work, the fabrication of simple, fast-response and highly selective ratiometric probe for sensitive visual detection of CLP antibiotic at trace levels in both indoor and outdoor is reported. For the construction of the ratiometric fluorescence probe (mMIP@YBCDs), two kinds of different carbon dots with yellow emission (Y/CDs, 560 nm) and blue emission carbon dots (B/CDs, 440 nm) were used as target sensitive and as reference dyes respectively. Besides, molecularly imprinted mesoporous silica was used as a recognized part of the probe. Upon the addition of different concentrations of CLP, the fluorescence of Y/CDs was quenched significantly while the fluorescence intensity of B/CDs stayed constant which was accompanied by gradual fluorescence color change from yellow-to-blue. The ratiometric probe has a linear response in the range of 0.1–3 μgL−1 with a detection limit 0.035 μgL−1. The practicality of the ratiometric method was validated by the quantification of CLP in milk samples.

Impedimetric ultrasensitive detection of chloramphenicol based on aptamer MIP using a glassy carbon electrode modified by 3-ampy-RGO and silver nanoparticle

In this research work, a biosensor with a dual recognition system was fabricated and founded on a combination of aptasensing and the molecular imprinting union of the chloramphenicol (CAP) selective detection. CAP, is an antibiotic, was applied in veterinary and human in order to treat gram-positive and gram-negative infections. It is worth mentioning that CAP residue brings about earnest side effects on human health. According to this, in this sensing system, 3-aminomethyl pyridine functionalized graphene oxide (GO) (3-ampy-RGO) has been coated on the surface of GCE. Afterwards, the silver nanoparticle (AgNPs) was coated on the 3-ampy-RGO/GCE and, then, the CAP complex-amino-aptamer (NH2-Apt[CAP]) was attached to the AgNP/3-ampy-RGO/GCE using a kind of bonding formation of Ag-N. In this sense, it is worth noting that the resorcinol electropolymerization around the complex of aptamer/CAP would confine the complex and, then, retain the aptamer. Following the CAP removal, the MIP cavity, as it was supposed, synergistically acted with that of the embedded aptamer in order to construct a nanohybrid receptor. Interestingly, the double exact property of the molecular imprinting polymers and aptamers led to the superb sensing properties. In the mentioned system it was illustrated that the linear range was from 1.0 pM to 1.0 nM with the detection limit of 0.3 pM; consequently, as observed, it was better than or as good as other similar assays. Moreover, the mentioned system whose activity was observed in the various interferences presence showed great selectivity in detected the CAP. Finally, the designed sensor exhibited outstanding results when applied to detect CAP in milk samples.

On-line solvent exchange system: Automation from extraction to analysis

Removal of organic solvent from sample extracts is required before analysis by reversed phase HPLC to preserve chromatographic performance and allow for bigger injection volumes, boosting sensitivity. Herein, an automated on-line extraction evaporation procedure is integrated with HPLC analysis. The evaporation occurs inside a 200 μm microfluidic channel confined by a vapor permeable membrane. A feedback control algorithm regulates evaporation rate keeping the output flow rate constant. The evaporation process across this membrane was firstly characterized with water/solvent mixtures showing organic solvent removal capabilities. This system allowed continuous methanol, ethanol and acetonitrile removal from samples containing up to 80% organic solvent. An evaporative injection procedure was developed demonstrating the use of the device for fully integrated extract reconstitution coupled to HPLC analysis, applied to analysis of the antibiotic chloramphenicol in milk samples. Sample reconstitution and collection was performed in less than 10 min and can be executed simultaneously to HPLC analysis of the previous sample in a routine workflow, thus having minimal impact on the total sample analysis time when run in a sequence.

Ultrasensitive label-free electrochemical immunosensor based on PVA-co-PE nanofibrous membrane for the detection of chloramphenicol residues in milk

An ultrasensitive label-free amperometric immunosensor for the detection of chloramphenicol (CAP) residues in milk has been developed by using a screen-printed carbon electrode laminated with a layer of poly (vinyl alcohol-co-ethylene) (PVA-co-PE) nanofibrous membrane that is covalently immobilized with a CAP antibody (anti-CAP). The performance of the PVA-co-PE nanofiber membrane (PVA-co-PE NFM) on the electrode was compared with a PVA-co-PE casted membrane (PVA-co-PE CM), necessary fabrication steps and performance of the sensors were investigated by electrochemical impedance spectroscopy (EIS). The application of the PVA-co-PE NFM decreased the electron-transfer-resistance by about 4 times compared with a conventional PVA-co-PE casted membrane. Under the optimal conditions, the established immunosensor exhibited high sensitivity for determination of CAP in a range 0.01–10 ng mL−1, with a limit of detection of 0.0047 ng mL−1. In addition to the good selectivity, reusability and stability over time, the prepared immunosensor was successfully used in the detection of CAP in milk samples without any pretreatment.

Amperometric aptasensing of chloramphenicol at a glassy carbon electrode modified with a nanocomposite consisting of graphene and silver nanoparticles

A nanocomposite prepared from reduced graphene oxide (rGO) and silver nanoparticles (AgNPs) is used in an electrochemical aptasensor for the sensitive and selective determination of the antibiotic chloramphenicol (CAP). The nanocomposite was obtained by electrostatic assembly of AgNPs on the surface of polyelectrolyte-functionalized rGO and then used to modify a glassy carbon electrode. The biosensor is then obtained by immobilizing the aptamer against CAP. When incubated with solutions of CAP, the sensor surface is loaded with CAP due to aptamer recognition. The captured CAP can be electrochemically reduced to yield a current that is strongly enhanced as a result of the excellent electrocatalysis property of the graphene/AgNP-nanocomposite. Under optimum conditions, the calibration plot is linear in the 0.01 to 35 μM concentration range, with a 2 nM detection limit (at 3σ). The sensor is reproducible, stable, selective over homologous interferents, and performs excellently when analyzing CAP in milk samples.

Selective Determination of Chloramphenicol in Milk Samples by the Solid-Phase Extraction Based on Dummy Molecularly Imprinted Polymer

A novel dummy molecularly imprinted polymer (MIP) for selective extraction and preconcentration of chloramphenicol (CAP) has been successfully developed by precipitation polymerization using thiamphenicol (TAP) as the dummy template, methacrylic (MAA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker, and methanol as the porogen. The performances and recognition mechanism of MIPs and non-molecularly imprinted polymers (NIPs) has evaluated in terms of adsorption isotherms and adsorption kinetics. The results showed that the MIPs exhibited significant specific recognition toward CAP in water with a large adsorption capacity. To test the feasibility of MIP in real samples, the obtained MIPs were applied as the selective sorbents for the solid-phase extraction of CAP from milk samples. Under optimized conditions, a rapid, convenient, and efficient method for the determination of CAP in milk samples based on MISPE coupling with high-performance liquid chromatography tandem mass spectrometry (LC-MS/MS) was throughly established. The method showed excellent recoveries (96.04~108.68%) and precision (RSDs <7.97%, n = 5) for milk samples spiked at three concentration levels (2, 5, and 10 μg L−1). The results demonstrated that the CAP in milk samples could be separated and purified through molecularly imprinted solid-phased extraction (MISPE), and this method could solve the leakage of template by the employment of dummy template effectively.

Selective detection of chloramphenicol in milk based on a molecularly imprinted polymer-surface-enhanced Raman spectroscopic nanosensor

In this study, a novel hybrid molecularly imprinted polymer (MIP) with a surface-enhanced Raman spectroscopy (SERS) sensor was proposed for the detection of chloramphenicol in milk. The MIP was prepared by precipitation polymerization, and the template molecule was extracted by ultrasonic wave. The polymer was placed in a sodium citrate reduction reaction to prepare the chloramphenicol–MIP–Au substrate. The optimal detection conditions were carried out in a mixed solution of methanol and water (1:9). The sensor can be used to detect chloramphenicol in milk samples with a detection limit of 0.1 µg/ml. The chloramphenicol–MIP–Au substrate served not only as an enrichment medium but also as an enhancement substrate base for SERS detection. Experimental results showed that the MIP hybrid as a SERS platform owned potential for simplifying the detection step and highly selective detection of chloramphenicol in milk. Copyright © 2016 John Wiley & Sons, Ltd.

Fluorescence quenching for chloramphenicol detection in milk based on protein-stabilized Au nanoclusters

In the present study, we report a simple and rapid method for sensitive and selective determination of chloramphenicol (CAP) based on fluorescence of bovine serum albumin-stabilized Au nanoclusters (BSA-AuNCs). The BSA-AuNCs exhibit strong red emission. Upon addition of CAP to BSA-AuNCs, the fluorescence intensity of AuNCs shows a dramatic decrease attributing to the photo-induced electron transfer process from the electrostatically attached CAP to the BSA-AuNCs. The effects of pH, amount of BSA-AuNCs, temperature and reaction time on the detection of chloramphenicol were investigated. Under the optimal conditions, trace amounts of CAP could be detected. The linear working range is 0.10–70.00μM with a detection limit 33nM (S/N=3). In addition, the proposed method has been successfully applied to the detection of CAP in milk samples and largely improves the application of spectral method for quantitative analysis of CAP.

Determination of Chloramphenicol in Milk Using a QuEChERS-Based on Liquid Chromatography Tandem Mass Spectrometry Method

A quantitative method for the determination of chloramphenicol in milk samples was developed based on the QuEChERS (quick, easy, cheap, effective, rugged, and safe) approach for liquid chromatography–tandem mass spectrometry (LC–MS/MS). Homogenized milk samples were extracted with acetonitrile. The partitioning step was performed after the addition of magnesium sulfate and sodium chloride. Chloramphenicol was determined using the electrospray negative ionization mode with tandem mass spectrometry. The procedure was validated according to the requirements of Commission Decision 2002/657/EC. The apparent recovery ranged from 90% to 110% and within-laboratory reproducibility was lower than 12%. The calculated limit of decision was 0.10 μg kg−1 and the detection capability was 0.15 μg kg−1. Validation results demonstrated that this method fulfills criteria for the determination of chloramphenicol in milk.

Magnetic Chitosan Nanocomposite Used as Cleanup Material to Detect Chloramphenicol in Milk by GC-MS

A novel method for determination of chloramphenicol in milk samples was introduced. Magnetic Fe3O4@chitosan nanocomposites were synthesized by adding chitosan to the surface of magnetic Fe3O4 using glutaraldehyde as cross-linker. Extraction with ethyl acetate, the study used the magnetic Fe3O4@CS as cleanup materials, without an additional cleanup step, to detect chloramphenicol in milk samples. To obtain maximal cleanup efficiency, several parameters were investigated including amount of magnetic materials, pH of the solution, purification time, and temperature. Under the optimal conditions (the amount of 100 mg/g of magnetic materials, pH = 5, 10 min, and 20 °C), the sensitivity of the proposed method had improved about tenfold than that of without magnetic materials. Moreover, the decision limits and detection capability were 0.05 and 0.11 μg/kg, respectively, which were comparable to those measured by most methods. The rapid, simple, solvent-saving, and efficient method was proved to be robust in monitoring [d(−)-theo-2-dichloroacetamido-1-p-nitrophenyl-1,3-propanediol] in milk samples.