Detection Of Chloramphenicol In Milk Research Articles

Point-of-care monitoring of milk quality by rapid Immunofluorescence with mechanical deformation of the hydrogel microspheres

Point-of-care testing (POCT) of chloramphenicol (CAP) in fresh milk from private ranches is essential to ensure food safety. It’s still a great challenge to meet simultaneously rapid and accurate during POCT of CAP. Here, we present a POCT device integrating hydrogel microsphere immunoassay and smartphone Fourier analysis for fast and sensitive detection of CAP. Based on the excellent biocompatibility and outstanding mechanical properties of hydrogel microspheres (100 μm), the antibody activity can be maintained and the mechanical deformation of the hydrogel cross-linking lattice is induced by squeezing to accelerate the antigen-antibody reaction of CAP and anti-CAP antibodies. The signal-to-noise ratio of the detection result is optimized adaptively by a designed microsphere Fourier analysis algorithm for precise CAP concentration detection. The results show that the method decreases incubation time from 60 min to 25 min and meets detection limit requirements of industrial production (0.05 ng/mL, with a dynamic range of 0.05–8 ng/mL). This method not only achieves rapid and accurate on-site detection of CAP in milk but also applies to other low concentrations of harmful substances detection in food field.

A Novel Electrochemical Sensor for Chloramphenicol Based on MXenes and Carbon Nanofiber from Bacterial Cellulose

In this study, three-dimensional porous MXene/carbon nanofiber (CNF) nanocomposites were prepared by assembling environmentally friendly and inexpensive bacterial cellulose (BC) gel sheets as a carbon source with novel two-dimensional MXenes nanoplate clusters and pyrolyzing the composite. The structure, morphology, and electrochemical properties of MXene/CNF was characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and electrochemical techniques. The experimental results revealed that the MXene/CNF nanocomposites had excellent electrical conductivity, large specific surface area, abundant active sites, and excellent electrochemical properties. The sensitive electrochemical determination of chloramphenicol (CAP) was achieved by constructing an electrochemical sensor using the MXene/CNF composite. The response current values of the MXene/CNF sensor exhibited a good linear response with CAP concentration ranging from 0.03-25μM, with a low detection limit of 9 nM. In addition, the sensor demonstrated good repeatability and reproducibility with relative standard deviations of 2.94 and 3.29%, respectively. Remarkably, the developed sensor was successfully used for the real-time detection of CAP in milk and jasmine tea beverage and satisfactory rates were obtained.

Construction of a Cd(II)-Based Metal-Organic Framework for Selective Luminescent Sensing of Chloramphenicol in Milk and Honey Samples

A new and water-stable metal-organic framework, [Cd2(L)2(tmd)]·3H2O (MOF 1), was successfully synthesized by mixed ligands of H2L and tmd under solvothermal condition (H2L= 5-acetamidoisophthalic acid, tmd= 4,4-trimethylenedipyridine). Single-crystal X-ray diffraction shows that the structural unit of MOF 1 is a tetranuclear [Cd4(L)6] primary building unit. Fluorescence sensing experiments revealed that MOF 1 exhibited selectivity and sensitivity detection of Chloramphenicol (CHL) antibiotic in aqueous solutions. The fluorescence quenching effect showed that MOF 1 had a very low detection limit for CHL (LOD= 0.11 μM). More importantly, MOF 1 can be used as a new fluorescence sensor for the detection of CHL in milk and honey samples with very good recoveries of 98.2-103.0 % and 97.0-98.9 %, respectively. Furthermore, the internal filtration effect (IFE) and photoelectron electron transfer (PET) may be responsible for the fluorescence quenching efficiency.

An Advanced Molecularly Imprinted Photochemical Sensor Based Carbon Quantum dots for Highly Sensitive Detection of Chloramphenicol in Food.

A facile method which combines the advantages of carbon quantum dots and molecular imprinting technology to design a fluorescence molecular imprinting sensor for the high sensitivity and selective detection of chloramphenicol. The fluorescent molecule imprinted polymers are synthesized by sol-gel polymerization using carbon quantum dots as functional monomers and fluorescent sources, TEOS as crosslinkers, breaking with the traditional understanding of an additional functional monomer. Under optimal experimental, as the concentration of chloramphenicol increases, the fluorescence intensity of the fluorescence molecule imprinting sensor gradually decreases. The concentration of chloramphenicol is linear in the range of 5-100µg/L and the detection limit is 1µg/L (N/S = 3). The sensor is able to detect chloramphenicol in milk, enabling the application of real samples. The results show that this work provides an easy method to preparing fluorescent molecular imprinting sensors for the detection of chloramphenicol in milk.

Novel Dual-Signal SiO2-COOH@MIPs Electrochemical Sensor for Highly Sensitive Detection of Chloramphenicol in Milk.

In view of the great threat of chloramphenicol (CAP) to human health and the fact that a few producers have illegally used CAP in the food production process to seek economic benefits in disregard of laws and regulations and consumer health, we urgently need a detection method with convenient operation, rapid response, and high sensitivity capabilities to detect CAP in food to ensure people's health. Herein, a molecularly imprinted polymer (MIP) electrochemical sensor based on a dual-signal strategy was designed for the highly sensitive analysis of CAP in milk. The NiFe Prussian blue analog (NiFe-PBA) and SnS2 nanoflowers were modified successively on the electrode surface to obtain dual signals from [Fe(CN)6]3-/4- at 0.2 V and NiFe-PBA at 0.5 V. SiO2-COOH@MIPs that could specifically recognize CAP were synthesized via thermal polymerization using carboxylated silica microspheres (SiO2-COOH) as carriers. When the CAP was adsorbed by SiO2-COOH@MIPs, the above two oxidation peak currents decreased at the same time, allowing the double-signal analysis. The SiO2-COOH@MIPs/SnS2/NiFe-PBA/GCE sensor used for determining CAP was successfully prepared. The sensor utilized the interactions of various nanomaterials to achieve high-sensitivity dual-signal detection, which had certain innovative significance. At the same time, the MIPs were synthesized using a surface molecular imprinting technology, which could omit the time of polymerization and elution and met the requirements for rapid detection. After optimizing the experimental conditions, the detection range of the sensor was 10-8 g/L-10-2 g/L and the limit of detection reached 3.3 × 10-9 g/L (S/N = 3). The sensor had satisfactory specificity, reproducibility, and stability, and was successfully applied to the detection of real milk samples.

RNA-cleaving deoxyribozyme-linked immunosorbent assay for the ultrasensitive detection of chloramphenicol in milk

In this presented work, an artificial deoxyribozyme was employed as the substitute for horseradish peroxidase (or alkaline phosphatase) in ELISA for generating amplified signals. The feasibility of the proposed deoxyribozyme-based ELISA (DLISA) was demonstrated in the detection of a forbidden veterinary drug, chloramphenicol. And its efficiency was praised since that ultrahigh sensitivity was accomplished with a detection limit of 0.1 ng/L. The wide linear range from 0.000001 μg/mL to 1.0 μg/mL, as well as good recoveries from 86 % to 104 % in whole milk samples showed its excellent practical performances. Besides, the DLISA was worth popularizing due to the easy connection of antibody and DNAzyme through a facile functionalization process of gold nanoparticles. These advantages showed the possibility of DLISA for developing commercial kits, and the utilization of flexible DNA fluorescent probes in DLISA would inspire more work on innovations.

Synthesis of octadecylamine-derived carbon dots and application in reversed phase/hydrophilic interaction liquid chromatography

In order to make up for the deficiencies of traditional C18 column for separating strong polar compounds, combined with the good hydrophilicity of carbon dots (CDs), novel octadecylamine-derived CDs denoted as C18-CDs are designed, synthesized and applied in RPLC/HILIC mixed-mode chromatography with good separation performance towards both hydrophobic and hydrophilic compounds. C18-CDs are synthesized by simple one-step solvothermal method using octadecylamine and citric acid as carbon sources, and C18-CDs with proper polarity are collected through column chromatography purification. This C18-CDs decorated silica column showed good separation performance for polycyclic aromatic hydrocarbons and alkylbenzenes under RPLC mode. Hydrophilic compounds including sulfonamides, nucleosides and nucleobases also achieved good resolution in HILIC mode. Hydrophobic and π-π stacking interactions play major retaining roles in RPLC, whereas hydrophilic partitioning and hydrogen bond interactions turn to the main retention interactions under HILIC mode. This C18-CDs/SiO2 column was applied for the fast detection of chloramphenicol in milk without complex sample pretreatment process. Quantitative relationship between the peak area and the concentration of chloramphenicol was established with linear equation of A = 1677c + 173. Satisfactory spiked recoveries in the range of 94.1–109.0% were obtained. This work not only proposes a simple method for improving the polarity of C18 column through forming octadecane into CDs, but also provides novel CDs with certain hydrophobicity/hydrophily suitable for mixed-mode chromatography.

Exonuclease III-assisted nucleic acid amplification fluorescence immunoassay for the ultrasensitive detection of chloramphenicol in milk

Herein, an integrated approach based on immunoassay and exonuclease III-assisted nucleic acid amplification (EANA), which is defined as exonuclease III-assisted nucleic acid amplification fluorescence immunoassay (EA-NAFIA) was developed for the detection of chloramphenicol (CAP). Au nanoparticles (AuNPs) modified with antibody and DNA were used as bifunctional probe, in which antibody captured the target, and DNA initiated the signal amplification through EANA. A detection linear range from 0.01 to 5 ng/L was obtained under optimized conditions, and the detection limit was as low as 0.001 ng/L. There was no cross reaction with streptomycin, kanamycin, gentamicin, thiamphenicol. This assay was successfully applied to detect CAP in skim milk, with acceptable recoveries. This kind of integrated strategy demonstrated the excellent hybrid performance of indirect immunoassay with ultrasensitive sensitivity.

An fluorescence resonance energy transfer sensing platform based on signal amplification strategy of hybridization chain reaction and triplex DNA for the detection of Chloramphenicol in milk

The use of chloramphenicol (CAP) in food had been strictly regulated or banned in many countries. Herein, an enzyme-free fluorescence resonance energy transfer (FRET) strategy was established for sensitive, rapid and specific detection of CAP in milk, which was based on triplex DNA and hybridization chain reaction amplification. CAP can specifically bind to the aptamer and release the trigger sequence, causing HCR to efficiently prime and forming triplex DNA, hence the FRET pairs (FAM and TAMRA) were close enough to cause fluorescent decreases. Consequently, CAP can be quantitatively detected by measuring the fluorescence reduction at 520 nm, and the reliability of the method was confirmed by enzyme-linked immunosorbent assay. The limit of CAP detection for 1.2 pg·mL−1, and the average recoveries of milk samples were 97.5%–106%, and the relative standard deviation were 3.9%–5.3%. Thus, this method has a wide range of potential applications in CAP detection.

Rapid quantitative detection of chloramphenicol in milk by microfluidic immunoassay

Chloramphenicol (CAP) is a toxic substance for human health, and detection of CAP residues in milk is necessary. However, most of the traditional CAP detection methods including high performance liquid chromatography-tandem mass spectrometry (HPLC-MS) and enzyme-linked immunosorbent assay (ELISA) are time-consuming and complicated. Herein, an automated microfluidics system for CAP detection in milk was developed. The residual CAP of multiple milk samples was quantitatively detected via competitive immunoassay in a single microfluidic chip simultaneously and automatically, and the reliability of the method was confirmed by flow cytometry. Completion of the detection by the system required less than 20 min and the cost for the detection of ten samples was about US$2.5. The limit of detection was 0.05 µg L−1, and the recovery rate of CAP in milk ranged from 91.3% to 105.5%. The microfluidic system developed in this study exhibited considerable potential in the point-of-care testing (POCT) of CAP in milk.

Tunable Synthesis of CoP and CoP2 Decorated 3D Carbon Nanohybrids and the Application of CoP2 Decorated One in Electrochemical Detection of Chloramphenicol in Milk and Honey

Cobalt phosphides embedded in electrocatalysts with low Co/P ratio have recently garnered a great deal of attention due to their high catalytic activities. However, compared to the studies on Co2P and CoP based catalysts, the studies on facile and controllable synthesis of CoP2 based catalysts are few. Herein, two types of cobalt phosphides embedded in 3D carbon nanohybrids (CoPx-N-C) with controllable Co/P ratio were developed via a facile one-step phosphidation-carbonization using a cobalt centered metal-organic framework, ZIF-67, as building block. Based on the high affinity between chloramphenicol (CAP) and cobalt phosphide, the as-prepared CoPx-N-C hybrids were further utilized as electrode components in electrocatalytic determination of CAP in milk and honey. The abundant cobalt phosphide component exhibits high affinity to CAP thus favors its adsorption and facilitates the followed redox reaction. The P-rich CoP2-N-C shows better performance than the metal-rich CoP-N-C in CAP detection, owing to its better electro-activity. The developed CoP2-N-C based sensor exhibits good analytical performance with low detection limit of 0.044 μM (signal-to-noise ratio, S/N = 3) and wide linear range (0.2∼40 μM and 40∼200 μM). The proposed sensor was also applied in the analyses of spiked milk and honey samples, demonstrating its feasibility in CAP analysis.

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.

Design and fabrication of an aptasensor for chloramphenicol based on energy transfer of CdTe quantum dots to graphene oxide sheet.

Detection and quantification of chloramphenicol have played essential roles in the effort to minimize food safety risk. Herein, a sophisticated "turn on" aptasensor based on aptamer-CdTe quantum dots (Apt-QDs) and graphene oxide (GO) was developed for chloramphenicol sensing. In this assay, the fluorescence of CdTe QDs-Apt was efficiently quenched through energy transfer from QDs-Apt to GO, and chloramphenicol was detected by recovering the quenched fluorescence due to specific binding between aptamer and chloramphenicol. The results indicated that the addition of a CdTe QDs-labeled aptamer to a GO solution (250μg/mL) led to a high quenching efficiency, yielding over 90% fluorescence quenching. Using a series of chloramphenicol concentrations (0.1 to 10nM) aptasensor provides a limit of detection and limit of quantification at 98pM and 987pM, respectively. Linearity of response over chloramphenicol was demonstrated (r>0.99). Furthermore, the GO-based aptasensor exhibited excellent selectivity toward chloramphenicol compared to other synthetic drugs with similar structures such as thiamphenicol, metronidazole and nitrofurantoin. Good reproducibility and precision (RSD 4.73%, n=10) of the assay indicates the ability of the aptasensor for routine quantitative trace analysis of chloramphenicol. Our results suggested that the prepared aptasensor was also well qualified for the detection of chloramphenicol in milk with a limit of detection of 0.2ppb.

Quantum dot-based lateral flow immunoassay for detection of chloramphenicol in milk

A novel rapid (20 min) fluorescent lateral flow test for chloramphenicol (CAP) detection in milk was developed. The chosen format is a binding-inhibition assay. Water-soluble quantum dots with an emission peak at 625 nm were applied as a label. Milk samples were diluted by 20 % with phosphate buffer to eliminate the matrix effect. The result of the assay could be seen by eye under UV light excitation or registered by a portable power-dependent photometer. The limit of CAP detection by the second approach is 0.2 ng/mL, and the limit of quantitation is 0.3 ng/mL.

Establishment of magnetic beads-based enzyme immunoassay for detection of chloramphenicol in milk

In this research, magnetic beads-based enzyme immunoassays were investigated for rapid analysis of chloramphenicol (CAP) in milk. To improve sensitivity of CAP determination, two kinds of immunomagnetic separation methods were designed and compared. Magnetic polystyrene microspheres were conjugated with anti-CAP antibody (Method I) or goat-anti-mouse IgG (Method II). The whole determination could be finished in 1.25 h. Both methods showed high sensitivity to CAP in buffer, and obtained an IC(50) value of 0.05 ng mL(-1) for Method I and 0.4 ng mL(-1) for Method II. The methods showed high specificity, only showing a little cross-reaction towards CAP succinate. The two methods were applied to detect CAP in milk. The recovery rates were 80-106% and the coefficients of variation (CVs) were 4.7-15%. The immunomagnetic assay showed promising potential in rapid screening field for CAP analysis. Between the two methods, Method I is more sensitive, and Method II is more suitable for producing a general assay by changing a primary antibody for another analyte.

Development of a homogeneous immunoassay based on the AlphaLISA method for the detection of chloramphenicol in milk, honey and eggs

A homogenous light-induced chemiluminescence immunoassay was developed using AlphaLISA technology for the detection of chloramphenicol (CAP). This technology is based on two different kinds of bead, namely light-sensitive donor beads and beads containing chemiluminescers, also called acceptor beads. A competitive CAP AlphaLISA method was established using artificial antigen-coated acceptor beads, polyclonal antibodies, biotinylated goat anti-rabbit IgG and streptavidin-coated donor beads. The sensitivity of detection was 0.0086 ng mL⁻¹ and the working range was from 0.0096 to 25 ng mL⁻¹. The intra- and inter-assay coefficients of variation were both below 10%. The average recovery rates at spiked levels of 0.05-10 ng mL⁻¹ were 103.2, 108.4 and 91.6% for milk, honey and eggs respectively. The data obtained from the samples showed good correlation with ELISA results. The CAP AlphaLISA method is highly sensitive, specific and rapid and is suitable for screening large quantities of samples.

Inter-laboratory studies for the evaluation of ELISA kits for the detection of chloramphenicol residues in milk and muscle

The use of chloramphenicol in veterinary medicine was banned in the EU in 1994. As the Community Reference Laboratory for antibiotic residues in food of animal origin, one of our functions is to organize inter-laboratory studies. A first inter-laboratory study for the analysis of chloramphenicol (CAP) in milk by ELISA kits was organized in 2001 and a second one for the detection of CAP in pig muscle by ELISA kits in 2002. These studies were intended to allow participants to control their CAP ELISA methods when used routinely and also to compare the performances of various ELISA kits for the detection of chloramphenicol in milk (commercial or in-house kits). In 2001, 15 participants received ten randomly coded frozen milk samples (four blank samples and six spiked milk samples from 0.5 to 5.0 μg/l). In 2002, 20 participants received eight randomly coded frozen muscle samples (two blank samples and six incurred muscle samples from 2.1 to 6.5 μg/kg). They were asked to analyse each sample in triplicate with the ELISA kit of their choice. Different kits from different suppliers were used and compared in the two studies. The results of the two inter-laboratory studies on ELISA kits were satisfactory regarding qualitative results. The global rates of false compliant results of 2.2% for milk and 0.0% for pig muscle samples were lower than 5% whichever kit was used. The global rates of false non-compliant results (16.7% and 10% for milk and muscle respectively) were also satisfactory. The distribution of false non-compliant results depends on the kind of kit used and on the detection limit for milk as well as for muscle. Moreover the sample preparation was very important to avoid false non-compliant results. Finally, this study demonstrates that ELISA kits for chloramphenicol in milk and muscle globally show good repeatability and accuracy. So these kits could be considered as suitable tests for screening purposes.