Chloramphenicol Research Articles

KOH‐Activated Pinecone Biochar for Efficient Chloramphenicol Removal From Aqueous Solutions

ABSTRACTThe emerging pollutant chloramphenicol (CAP) is highly environmentally persistent and biotoxic, causing extreme environmental harm. This study investigates the removal of CAP from aqueous solutions using biochar derived from pinecones. The biochars were activated at 800°C using KOH with different mass ratios to the carbonized sample (2:1, 4:1, and 6:1). Among them, the biochar with a KOH ratio of 4:1 (PCK4‐800) exhibits the highest pore volume (1.8 cm3 g−1) and a specific surface area (3131.6 m2 g−1). Batch experiments reveal that the CAP adsorption capacity of the biochar is positively correlated with its specific surface area. At pH 7, PCK4‐800 achieves a removal efficiency of up to 92% for a 100 mg L−1 CAP solution using a dosage of just 0.1 g L−1. This performance surpasses that of recently reported adsorbents. Kinetic and thermodynamic model fitting results indicate that chemical adsorption within a monomolecular layer dominates physical adsorption. The primary adsorption mechanisms involve pore filling and π‐π interactions, while secondary mechanisms include electrostatic effects and hydrogen bonding. Thermodynamic parameters confirm that the adsorption process is endothermic and spontaneous. Moreover, the removal efficiency of PCK4‐800 remains above 80% after five regeneration cycles. In summary, the high removal efficiency and excellent regeneration potential of PCK4‐800 demonstrate its suitability as an effective adsorbent for antibiotic removal.

Stabilize the oxygen vacancies in ZnO via altering local electronic structure by Co and Ni doping: A novel strategy for achieving durable visible light driven photo-Fenton degradation of chloramphenicol

The build-up of antibiotics, harmful pollutants, and pharmaceutical products has led to the significant contamination of environmental water bodies. Hence, the advancement of oxidation methods such as light-induced photo-Fenton degradation has proven crucial for efficiently desolating these harmful pollutants. Herein, we report a novel photo Fenton catalyst, Co and Ni co-doped ZnO (Zn1-x-yCoxNiyO) nanorods (NRs) for enhanced photocatalytic degradation of chloramphenicol (CAP) under visible light irradiation. The NRs were synthesized via the ultrasonication-assisted solvothermal method. Among the different Co and Ni doping concentrations, Zn0.96Co0.03Ni0.01O NRs showed superior photodegradation efficiency of 94.2%. Here, •OH radicals were identified as predominant reactive oxygen species in photocatalytic degradation by electron spin resonance (ESR) analysis and scavenging assay. The effect of various environmental parameters such as nanoparticle dosage, CAP concentration, pH, and ions were investigated to understand the impact of these parameters on the degradation of CAP. Further, Zn0.96Co0.03Ni0.01O NRs were stable for six consecutive photodegradation cycles, which showed their excellent efficiency and reusability for prolonged usage. Photostability was further confirmed by XPS and XRD analysis of the used photocatalyst. Also, the photodegradation pathway of CAP was predicted by identifying the intermediate compounds via GC-MS analysis. This approach holds promise for the efficient visible-light-driven degradation of pharmaceutical pollutants including CAP and contributes to the advancement of sustainable water treatment technologies.

Lignocellulosic carbon sheets-based hybrid electrochemical sensor for ultra-sensitive detection of chloramphenicol.

Efficient detection of chloramphenicol (CAP) in the environment and food products is crucial for addressing global health and environmental safety concerns. This study presents the development of a cost-effective hybrid electrocatalyst comprising lignocellulosic carbon sheets, graphene oxide, and manganese oxide (LCSs/GO@MnO2) for CAP detection using a simple electrochemical sensor fabricated on a glassy carbon electrode (GCE) substrate. The synergistic interaction between LCSs, GO, and MnO2 enhance the electroactive surface area of GCE, facilitating effective dispersion and electrode modification. This composite material significantly improves electrical conductivity and provides numerous electroactive sites for electrochemical CAP detection via voltammetric techniques. The developed sensor demonstrates a rapid electron transfer rate, enhancing electrode sensitivity for CAP detection at a low overpotential (-0.5717V) and an optimal pH (7.0). The sensor exhibits a wide linear range (0.017-477.247μM), excellent sensitivity (105.22μAμM-1 cm-2), and a low limit of detection (1.2nM) with enhanced charge carrier efficiency. Additionally, the sensor shows good cycle stability, reproducibility, selectivity, and trace-level CAP sensing applicability in food samples at a low cost. These features make the sensor a promising platform for monitoring antibiotics in various applications.

Oxygen Activation Biocatalytic Precipitation Strategy Based on a Bimetallic Single-Atom Catalyst for Photoelectrochemical Biosensing.

The traditional biocatalytic precipitation (BCP) strategy often required the participation of H2O2, but H2O2 had the problem of self-decomposition, which prevented its application in quantitative analysis. This work first found that a bimetallic single-atom catalyst (Co/Zn-N-C SAC) could effectively activate dissolved O2 to produce reactive oxygen species (ROS) due to its superior oxidase (OXD)-like activity. Experimental investigations demonstrated that Co/Zn-N-C SAC preferred to produce highly active hydroxyl radicals (•OH), which oxidized 3-amino-9-ethyl carbazole (AEC) to produce reddish-brown insoluble precipitates. Based on this property, a unique oxygen-activated photoelectrochemical (PEC) biosensor was developed for chloramphenicol (CAP) detection. Cesium platinum bromide nanocrystals (Cs2PtBr6 NCs) were a new type of halide perovskite with lead-free, narrow band gaps, and water-oxygen resistance. Cs2PtBr6 NCs showed excellent cathodal PEC performance without an exogenous coreactant and were first used for PEC detection. As a "proof-of-concept application", Co/Zn-N-C SAC was introduced onto the surface of Cs2PtBr6 NCs by using the CAP dual-aptamer sandwich strategy. Co/Zn-N-C SAC activated dissolved O2 to produce ROS, which oxidized AEC to produce precipitates, quenching the cathodal PEC signal of Cs2PtBr6 NCs for CAP detection. In summary, this work first used SAC to overcome the restriction of the traditional enzymatic BCP strategy requiring H2O2, improved the stability and accuracy of quantitative analysis, and also broadened the application range of coreactant-free perovskite-type PEC biosensors.

Context-specific inhibition of mitochondrial ribosomes by phenicol and oxazolidinone antibiotics.

The antibiotics chloramphenicol (CHL) and oxazolidinones, including linezolid (LZD), are known to inhibit mitochondrial translation. This can result in serious, potentially deadly, side effects when used therapeutically. Although the mechanism by which CHL and LZD inhibit bacterial ribosomes has been elucidated in detail, their mechanism of action against mitochondrial ribosomes has yet to be explored. CHL and oxazolidinones bind to the ribosomal peptidyl transfer center (PTC) of the bacterial ribosome and prevent incorporation of incoming amino acids under specific sequence contexts, causing ribosomes to stall only at certain sequences. Through mitoribosome profiling, we show that inhibition of mitochondrial ribosomes is similarly context-specific-CHL and LZD lead to mitoribosome stalling primarily when there is an alanine, serine, or threonine in the penultimate position of the nascent peptide chain. We further validate context-specific stalling through in vitro translation assays. A high-resolution cryo-electron microscopy structure of LZD bound to the PTC of the human mitoribosome shows extensive similarity to the mode of bacterial inhibition and also suggests potential avenues for altering selectivity. Our findings could help inform the rational development of future, less mitotoxic, antibiotics, which are critically needed in the current era of increasing antimicrobial resistance.

Bimetallic metal-organic frameworks as electrode modifiers for enhanced electrochemical sensing of chloramphenicol.

Anelectrochemical sensor is presentedfor the detection of the chloramphenicol (CAP) based on a bimetallic MIL-101(Fe/Co) MOF electrocatalyst. The MIL-101(Fe/Co) was prepared by utilizing mixed-valence Fe (III) and Co (II) as metal nodes and terephthalic acid as ligands with a simple hydrothermal method and characterized by SEM, TEM, XRD, FTIR, and XPS. Electrochemical measurements such as electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and differential pulse voltammetry (DPV) showed that bimetallic MIL-101(Fe/Co) had the faster electron transfer, larger electroactive area, and higher electrocatalytic activity compared with their monometallic counterparts due to the strong synergistic effect between bimetals. Inspired by these results, the MIL-101(Fe/Co)-based sensor was used to detect CAP. Some experiment parameters of pH, Fe and Co molar ratio, MIL-101(Fe/Co) volume, and DPV quiet time were optimized. The direct reduction mechanism of CAP was verified to involve four electrons and four protons process. Finally, the sensitive and selective CAP detection in the concentration range 1 to 200μM with a detection limit of 0.3μM was realized by the proposed sensor. The satisfactory recoveries in tap water and lake water indicated the practicability of the proposed electrochemical sensor. It is expected that this work may open up a paradigm for the preparation of MOF-based electrode modifiers with desired electrocatalytic performance for environmental pollution monitoring.

Aptamer-based fluorescence biosensor for rapid detection of chloramphenicol based on pyrene excimer switch.

Chloramphenicol (CAP) is widely used in treating bacteria infection in animals and humans. However, the accumulation of CAP in food and environment caused serious health risk to human. Consequently, sensitive and selective detection of CAP is of great importance in environmental monitoring and food safety. Among various analytical methods, aptamer-based biosensors exhibit great potentials for CAP detection. Here, we developed an aptamer-based biosensor for rapid fluorescence detection of CAP based on pyrene excimer switch by using a newly selected short DNA aptamer with high affinity. The aptamer was labeled with pyrene molecules at both ends. The binding of CAP to the aptamer probe caused two pyrene molecules close to each other and the formation of a pyrene excimer, which induced the increase of the fluorescence signal from the pyrene excimer. CAP detection was achieved by measuring the fluorescence signal changes of the aptamer probes with dual pyrene labels. Under optimized conditions, the developed aptamer biosensor showed a detection limit of 24.4nmol/L for CAP. The aptamer-based fluorescence sensor could quantify CAP in diluted tap water and lake water, exhibiting potentials for the application in real sample sensing of CAP.

Contaminated Characteristics Variation in Different Aquaculture Modes: A Case Study in Northern China

Various aquaculture modes have been developed to satisfy the growing demands of aquatic products. The contaminated characteristics may distribute along with the aquaculture modes, threatening the ecological environment to varying degrees. Herein, the five most common aquaculture modes (small-scale intensive mode, extensive free-range mode, concentrated contiguous mode, funnel-type mode, and recirculating aquaculture system) were selected to study the contaminated characteristics (including nine kinds of water quality parameters and eight kinds of antibiotics) in Henan Province, a province in northern China, and analysed using high-performance liquid chromatography tandem secondary mass spectrometry (HPLC–MS/MS). The funnel-type mode, as a unique mode developed in Henan Province, appears highest in nutrient content, wherein TN and TP concentrations reach 29.28 mg/L and 2.20 mg/L, respectively. The small-scale intensive mode has the highest average antibiotic concentration in five different aquaculture modes, with a concentration of 502 ng/L. Overall, the most abundant antibiotic was quinolones (QNs), followed by sulfonamides (SAs), chloramphenicols (CAs), and tetracyclines (TCs). Pearson correlation analysis showed that ENR had a strong positive correlation with TN, TP, and Zn, indicating the enrofloxacin (ENR) may have existed as the addictive in aquaculture feed. Moreover, the risk quotient (RQ) analysis indicated that ENR posed a medium to high risk, highlighting the importance of antibiotics man-agement in aquaculture. This work provides theoretical guidance for the formulation of aquaculture water pollutant control of different aquaculture modes.

A SERS and colorimetric dual-mode biosensor based on stimulus-responsive DNA/MOF-bound bimetallic nanozyme for the ultrasensitive detection of chloramphenicol in food.

Adual-mode detection platform utilizing colorimetric and Raman was developed based on the exponential amplification reaction (EXPAR) strategy and a "core-satellite" structure constructed by bimetallic nanozymes to detect chloramphenicol(CAP). Initially, DNA-gated metal-organic frameworks (MOFs) incorporating cascaded amplification were used to be nanocarriers for the colorimetric and Raman reporter molecules (3,3',5,5'-tetramethylbiphenyl; TMB). Subsequently, assembled DNA served as gatekeepers to create a stimulus-responsive DNA-gated MOF (TMB@DNA/MOF). Upon the introduction of the target, the efficient and isothermal EXPAR was initiated, producing numerous amplicons that facilitated the unlocking of pores and subsequent release of TMB. This process amplified the release signal, enhancing the selectivity and sensitivity of the biosensor. Moreover, through base complementary pairing, TMB@DNA/MOF and magnetic bimetallic nanozymes Fe3O4@MOF-gold nanostars (GNS) formed a stable "core-satellite" structure. The addition of H2O2 led to the oxidation of released TMB to oxTMB, resulting in a color change and generation of Raman signals. The biosensor exhibited excellent detection performance for CAP, with a colorimetric detection range of 1.00 × 10-4 ~ 2.50 × 10-7M and a detection limit of 2.07 × 10-7M, while the SERS detection range was 1.00 × 10-6 ~ 1.00 × 10-11M with a detection limit of 9.74 × 10-12M. Overall, this biosensor provided an effective method for detecting antibiotics in complex samples.

A Conjugated Oligomer with Drug Efflux Pump Inhibition and Photodynamic Therapy for Synergistically Combating Resistant Bacteria.

High expression of drug efflux pump makes antibiotics ineffective against bacteria, leading to drug-resistant strains and even the emergence of "superbugs". Herein, we design and synthesize a dual functional o-nitrobenzene (NB)-modified conjugated oligo-polyfluorene vinylene (OPFV) photosensitizer, OPFV-NB, which can depress efflux pump activity and also possesses photodynamic therapy (PDT) for synergistically overcoming drug-resistant bacteria. Upon light irradiation, the OPFV-NB can produce aldehyde active groups to covalently bind outer membrane proteins, such as tolerant colicin (TolC), blocking drug efflux of bacteria. The minimum inhibitory concentration of antibiotic model chloramphenicol (CHL) is reduced about 64 times, significantly resensitizing drug-resistant bacteria to antibiotics. Also, the probe can produce highly efficient reactive oxygen species (ROS) under light irradiation. Consequently, the unimolecular OPFV-NB-based system demonstrates insusceptibility to antibiotic resistance while maintaining significant antimicrobial effects (100%) against drug-resistant bacteria. More importantly, in vivo assays corroborate that the combined system greatly accelerates wound healing by eradicating the bacterial population, dampening inflammation, and promoting angiogenesis. Overall, the OPFV-NB not only counteracts antibiotic resistance but also holds tremendous PDT efficiency, which provides a promising therapeutic strategy for combating drug-resistant bacteria and treating bacteria-infected wounds.

Facile fabrication of sensing electrode based on CoFe-MOFs/MXene for ultrasensitive detection of picomolar chloramphenicol.

Precise detection of ultralow-level antibiotics, such as picomole, in aqueous environments is significant for human health, however, it presents a great challenge to the adsorption capacity and electrocatalytic ability of sensing materials. Here, we used a one-step hydrothermal method to in situ grow spindle-like CoFe-based metal-organic frameworks (MOFs) with a size of about 50nm in the region of hydrophilic MXene-loading hydrophobic carbon paper. By combining MOFs with abundant adsorption sites and MXene with high conductivity, the problems of adsorption and electrons transfer of ultralow-level antibiotics have been solved, and achieving precise detection of picomole-level antibiotics. As a result, the CoFe-MOFs/MXene/HCP sensing electrode exhibits the ultralow limit of detection with 33 pM and a wide detection range with 0.1nm-2.0mM for chloramphenicol (CAP) detection, as well as the designed sensor has excellent anti-interference, reproducibility, and stability. Importantly, the prepared sensing electrode exhibits reliable analytical results for CAP in real water samples, such as bottled water, milk, and urine, indicating that the prepared sensors have a great potential for application in the analysis of antibiotics in real samples.

Activating SERS Signals of Inactive Analytes: Creating an Energy Bridge between Metal/Molecule Energy Alignment via Metal/Semiconductor Transitions.

Surface-enhanced Raman spectroscopy (SERS) is a powerful analytical technique, yet it faces challenges with certain probe molecules exhibiting weak or inactive signals, limiting their applicability. In a recent study, we investigated this phenomenon using a set of four probe molecules─chloramphenicol (CAP), 4-nitrophenol (4-NP), amoxicillin (AMX), and furazolidone (FZD)─deposited on Ag-based nanostructured SERS substrates. Despite being measured under identical conditions, CAP and 4-NP exhibited SERS activity, while AMX and FZD did not. We also demonstrated that the alignment of the target molecule's lowest unoccupied molecular orbital (LUMO) energy level with the substrate's Fermi level plays a critical role in influencing the SERS signal. When the LUMO level diverges from the Fermi level, hindrance of the charge transfer process occurs due to a high potential barrier, leading to weak or absent SERS signals. To overcome this challenge, in this study, we introduce an approach inspired by metal-semiconductor interfacial charge transfer dynamics. By employing TiO2/Ag nanostructures, we not only enhance SERS signals for CAP and 4-NP but also activate signals for inactive molecules AMX and FZD. Importantly, we demonstrate that controlling the crystalline phase composition of the TiO2 semiconductor allows for tailored conduction band minimum energy level (ECBM) positions, significantly impacting the overall SERS efficiency of the TiO2/Ag substrate. Our findings highlight the pivotal role of the semiconductor's ECBM position in the energy alignment of the metal-semiconductor-analyte three-body interaction for an optimal SERS sensing platform. These findings also offer a novel strategy to enhance and activate the SERS phenomenon of important yet underexplored analytes.

Novel Dual-Potential Color-Resolved Luminophore Ru(bpy)32+-Doped CdSe QDs for Bipolar Electrode Electrochemiluminescence Biosensing.

The classical electrochemiluminescence (ECL) reagent Ru(bpy)32+ was first doped into CdSe QDs to prepare novel dual-potential color-resolved luminophore Ru-CdSe QDs. Ru-CdSe QDs emitted a strong red ECL signal at a positive potential with coreactant TPrA and a strong green ECL signal at a negative potential with coreactant K2S2O8. As a proof-of-concept application, this work introduced Ru-CdSe QDs into a dual-channel closed bipolar electrode (CBPE) system to construct an ECL biosensor for simultaneous detection of chloramphenicol (CAP) and kanamycin (KAN). Ru-CdSe QDs were dropped on BPE holes A and B for ECL emission. Cobalt single-atom catalysts (Co-N-C SACs) had superior electric double layer (EDL) performance and conductivity. It could greatly promote the electron transfer of the CBPE system and realize ECL signal amplification. Based on this characteristic, Co-N-C SACs were introduced into BPE hole C and driving electrode hole D, respectively, using the CAP and KAN split dual-aptamer sandwich strategy. During positive potential scanning, the polarity of BPE hole A was anode, and Ru-CdSe QDs emitted a red ECL signal. With the increase of CAP concentration, abundant Co-N-C SACs were introduced to the electrode surface. The positive potential ECL signal was increased for CAP detection. During negative potential scanning, the polarity of the BPE hole B was cathode, and Ru-CdSe QDs emitted a green ECL signal for KAN detection. Finally, a zero-background spatial-potential color-resolved CBPE-ECL biosensor was developed for dual-mode detection of CAP and KAN. This work explored a novel ECL luminophore to construct a CBPE-ECL sensor, which greatly facilitated the development of the ECL assay.

Fmoc-Pro-Phe-OMe dipeptide carbon sensor for simultaneous detection of chloramphenicol (CP) and furazolidone (FZ) toxic residues in food samples

In this work, we fabricated the Fmoc-Pro-Phe-OMe modified carbon paste electrode (FPPO/MCPE) and used it for electrochemical detection of CP and FZ in a 0.1 M phosphate buffer solution (pH = 7). We characterized the Fmoc-Pro-Phe-OMe and applied it for the electrochemical detection of CP and FZ. The Mass spectroscopy, 1HNMR, and FTIR measurements confirm the Fmoc-Pro-Phe-OMe chemical structure. Studying electrochemical sensor characteristics, variation of scan rate parameters, and electrode surface area is crucial for understanding and optimizing the performance of modified and unmodified carbon paste electrodes. The FPPO/MCPE-modified carbon paste electrode has better sensing capabilities than the unmodified bare carbon paste electrode (BCPE). The FPPO/MCPE sensor has two linear ranges: 50–450 μM (CP) with a detection limit of 0.014 μM and 50–450 μM (FZ) with a detection limit of 0.015 μM. The FPPO/MCPE sensor is highly sensitive, measuring 4.25 µA/µM/cm2 for CP and 4.1 µA/µM/cm2 for FZ. Scan rate and concentration tests demonstrate that the oxidation of CP and FZ is a diffusion-controlled electrode process. The FPPO/MCPE sensor also demonstrates excellent repeatability, reproducibility, stability, and selectivity for detection of CP and FZ. The use of FPPO/MCPE-sensor is demonstrated for the detection of FZ and CP in milk and honey samples.

Triple Helix Molecular Switch Cascade Multiple Signal Amplification Strategies for Ultrasensitive Chloramphenicol Detection.

A novel self-powered biosensor has been developed for the detection of chloramphenicol (CAP) based on difunctional triple helix molecular switch (THMS)-mediated DNA walkers. The biosensor utilizes the CAP aptamer as the recognition element, a DNA walker and capacitor as dual signal amplification strategies, and a digital multimeter (DMM) as the data readout equipment. In the presence of the target, the CAP aptamer in THMS specifically binds with CAP to release a signal transduction probe (STP) and opens the H1 hairpin structure in the biocathode to trigger the DNA walker and form a double-stranded DNA structure. Then, [Ru(NH3)6]3+ is electrostatically adsorbed on the double-stranded DNA structure through electrostatic adsorption and reduced to [Ru(NH3)6]2+ at the biocathode by accepting electrons entering at the bioanode. In DNA walkers, more double-stranded structures are formed, and a higher open-circuit voltage (EOCV) is observed. This self-powered biosensor with a detection limit (LOD) of 0.012 fM exhibits ultrasensitive CAP detection in milk in the range of 0.1-104 fM as well as excellent selectivity, stability, and reproducibility.

Solar Assisted Mitigation of Chloramphenicol and H2 Evolution Using CuNi Alloy Nanoparticles on h-BN Doped g-C3N4: A Comprehensive Approach Combining Synchrotron and DFT Analysis.

A simple one-step deposition-precipitation method was used to synthesize highly active and well-defined CuNi alloy bimetallic nanoparticles supported on h-BN/g-C3N4. The nanocomposite was applied for hydrogen gas evolution via seawater splitting and photocatalytic chloramphenicol (CHP) removal. Through TEM and synchrotron studies, the formation of CuNi alloy and uniform distribution of CuNi bimetallic nanoparticles on the h-BN/g-C3N4 surface was observed. The EXAFS analysis verified the successful formation of the alloy, while the XPS and XANES spectra showed that the bimetallic nanoparticles are in a metallic state. Additionally, XANES revealed nanoparticle distortion upon interaction with the support, confirming the effective formation of the nanocomposite. The nanocomposite achieved a maximum hydrogen evolution rate of 3658.9 μmol g-1 h-1 for 5 wt % CuNi(3:1)/h-BN/g-C3N4, outperforming CuNi(3:1) nanoparticles and pristine g-C3N4 by 1.82 and 4.31 times, respectively. Additionally, it degraded chloramphenicol with a rate constant (kapp) of 0.018 min-1. Optical and electrochemical analysis revealed enhanced charge mobility, extended lifetime, improved photostability, and superior photoresponse. X-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations attributed the performance to the synergy between the bimetallic nanoparticles and the h-BN/g-C3N4 sheet. DFT calculations demonstrated the effective breakdown of chloramphenicol and the promotion of hydrogen gas evolution, aligning with experimental observations. Cytotoxicity of CHP post-treatment was analyzed using Drosophila melanogaster (fruit fly) and the Oregon-R strain of D. melanogaster.

A simple lable-free aptasensor based on liquid exfoliated graphene modified electrode for chloramphenicol detection in milk

Antibiotic residues in animal derived foods considered as one of the most serious food contamination poses significant risks to human health. Conventional methods for antibiotic residue detection rely on expensive and bulky instruments, complicated sample pretreatment and time-consuming, thus limiting their applications. Consequently, developing miniaturized and low-cost analytical technology for ultrasensitive monitoring and accurate evaluation of antibiotic residues in foods is of great significance. Herein, a simple and label-free electrochemical sensing platform for the highly sensitive detection of chloramphenicol (CAP) in milk was demonstrated by employing aptamer specific for CAP as a biological recognition element and liquid exfoliated graphene (LEG) modified indium tin oxide electrode (LEG/ITO) as substrate. LEG is believed to be the most economic few-layer graphene with remarkable electrical properties and larger specific surface area not only promotes electron transfer but also provides a large number of binding sites for aptamers to be assembly immobilized via the π–π stacking of DNA bases. Under optimal experimental factors, the aptasensor displayed a wider linear range for detecting CAP (1 fM ∼ 100 nM), accompanied by a limit of detection (LOD) (1 fM), as well as satisfactory performance with specificity, reproducibility, and stability. In addition, the designed strategy allowed the direct analysis of actual milk samples and the recovery rates were from 97.92 % to 103.34 %, rendering a ideal sensing strategy for quantitative determination of various analytes in food by adapting the specific aptamer.

Comparative assessment of commercial ELISA kits for the screening of chloramphenicol residues in meat and aquaculture products according to European Regulation (EU) 2021/808 and to the new Reference Point for Action (Commission Regulation (EU) 2019/1871)

This study covered the evaluation of performance characteristics and validation of five commercial ELISA kits for the detection of a banned antimicrobial, chloramphenicol (CAP), in muscle and aquaculture products. CAP has been banned in the European Union since 1994, but is still authorised in some countries in the world. In 2019, the European Union set a new Reference Point for Action (RPA), decreasing the acceptable limit of CAP in animal tissues for human consumption from 0.30 µg/kg to 0.15 µg/kg. Validations were performed according to the European Regulation EC/2021/808 and to the European Guideline on Screening Method Validation (2023). The detection capabilities CCβ were all determined under the RPA, but were 3 to 15 times higher than the announced limit of detection (LOD). False negative rates were satisfactory for all the kits (≤ 5%) and false positive rates were acceptable. All of them were found out to be applicable to aquaculture products and meat at a common CCβ.

Photoelectrochemical immunosensor for chloramphenicol detection based on cation exchange reaction-mediacted photocurrent enhancement of ZnIn2S4/TiO2/Ti3C2 MXene coupled with controlled-release strategy.

Aphotocurrent enhancing photoelectrochemical (PEC) immunosensor was developedfor chloramphenicol (CAP) detection based on cation exchange reaction. The efficient split-type PEC immunosensor combined with controlled-release strategy was established using the ZnIn2S4/TiO2/Ti3C2 MXene (ZIS/T/M) composite as the photoactive material and CuO as the signal response probe. In the presence of target CAP, CuO-labeled CAP antibody (CuO-mAb) was introduced onto the microplate via a competitive-type immunoassay. Under acidic conditions, a large amount of Cu2+ released from CuO-mAb, which triggered a cation exchange reaction with the Zn2+ in ZIS/T/M-modified photoelectrode to generate CuxS, resulting in enhancingthe photocurrent. As a result, the quantitative detection of CAP was achieved by detecting the photocurrent change. Under optimized conditions, the linear range of the sensor was 1pg/mL to 50ng/mL, and the detection limit was 0.24pg/mL. The excellent PEC behavior of ZIS/T/M composite could be attributed to the fact that heterojunction formation improved the migration and separation of thephotocarrier. Additionally, by virtue of the photocurrent-enhancing strategy via cation exchange reaction and the controlled releasing signal amplification method of ion, the PEC immunosensor has high sensitivity and satisfactory accuracy, offering great potential applications in the determinationof CAP.

Lateral flow immunoassay based on aggregation induced emission nanobeads for the sensitive and accurate detection of chloramphenicol in pig hair

Chloramphenicol (CAP) is a once widely used antibiotic, which is able to cause great harm to human health, is banned in some countries or organizations such as China, USA and the European Union for animal breeding. Because CAP in pig hair degraded slower and had amount of residues, pig hair could be used as the target to detect CAP residues. In this study, a competitive lateral flow immunoassay (LFIA), whose label was aggregation induced emission fluorescent nanobeads (AIEFN), was firstly developed for the detection of CAP in pig hair samples. It exhibited a low limit of detection (0.001 μg/kg) and a broad linear range (0.0025–0.32 μg/kg). The recovery rate and coefficient variation with spiked pig hair samples were 88.50%–106.17 % and 1.01%–7.37 %, which indicated good accuracy of this assay. The result of AIEFN-LFIA for the detection of CAP in pig hair was consistent with that of liquid chromatography-mass spectrometry. This assay was rapid with the total detection duration of about 20 min. AIEFN-LFIA was able to be used for rapid, sensitive, accurate and convenient detection of CAP residues in pig hair samples.