Indirect Competitive Enzyme-Linked Immunosorbent Assay Based on Broad-Spectrum Antibody for Simultaneous Determination of Thirteen Fluoroquinolone Antibiotics in Rana catesbeianus

Visual detection of ciprofloxacin using a multi-emission ratiometric fluorescence sensor based on the molecularly imprinted polymers doped with terbium(III) ions

Ciprofloxacin (CIP) is a commonly used antibiotic, but its abuse may cause bacterial resistance, posing a high risk to the environment and human health. Herein, based on the molecular imprinting technology, this study proposed a ratiometric fluorescence sensor employing the "post-doping" strategy, which aims to be rapid, selective, and visually easy-to-use for CIP detection to address antibiotic residues and environmental risks. Specifically, by exploiting the "antenna effect" of lanthanide metal ions (Ln3+), terbium (III) (Tb3+) chosen as a fluorescence-assisted functional monomer as well as the red emitting CdTe quantum dots (QDs) as the internal reference signal were introduced into multi-emission Tb3+-CdTe@SiO2@MIPs (TbMIPs). With the increase of CIP concentration, the variations among the fluorescence peaks within a multi-emission ratiometric fluorescence sensor not only induce a broader range of color changes, but also produce a more sensitive and stable effect through self-internal standard correction. The sensor showed a good trend in a wide concentration range within 0.08-50 μM and provided a satisfactory detection limit of 0.018 μM, which had lower detection limit for CIP than most of methods. It had demonstrated exceptional selectivity and had been successfully used to efficiently detect CIP in real samples including seawater, river water, milk and urine. Furthermore, when integrated with smartphone-based data processing capabilities, this sensor enabled highly sensitive visual detection under the 365 nm UV lamp device. Through innovative development, the wide color transition observed with the sensor makes it highly suitable for practical applications, enhancing its usability for further real-time monitoring.

Recent Advances in Pretreatment Methods and Detection Techniques for Veterinary Drug Residues in Animal-Derived Foods

Veterinary drugs are extensively employed in livestock, poultry, and aquaculture, playing a crucial role in preventing and treating animal diseases, facilitating growth, and enhancing feed conversion rates. Nevertheless, veterinary drug residues in animal-derived foods pose a direct or potential threat to human life and health. Precise detection of these residues in animal-derived foods to ensure their safety has become an important mission. In this review, we sum up the current progress of applied pretreatment methods and detection techniques for veterinary drug residues in animal-derived foods. At present, sample pretreatment methods mainly consist of the following: liquid-liquid extraction; solid-phase extraction; immunoaffinity chromatography; Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method; and molecular imprinting technology. Detection techniques mainly involve chromatographic techniques, immunoassay techniques, fluorescence polarization immunoassay, and surface-enhanced Raman scattering. We also discussed the advantages and limitations of these technologies. Moreover, we point out the development direction and tendency of detection techniques in the future, providing references for the detection of veterinary drug residues in animal-derived foods.

Dual-Mode Quantitative Immunochromatographic Assay for Highly Sensitive On-Site Detection of Ciprofloxacin in Fish Products

Ciprofloxacin has been extensively utilized in aquaculture due to its remarkable efficacy in preventing and treating bacterial infections in fish animals. However, the widespread application of ciprofloxacin has led to significant residue accumulation, necessitating the development of rapid, sensitive and specific detection methods. In this study, we developed a novel dual-mode quantitative immunochromatographic assay based on a portable reader and a photothermal instrument, enabling on-site ciprofloxacin detection. Under optimized conditions, the portable reader mode (Mode 1) achieved a detection range of 0.1-100.0 ng/L with a limit of detection (LOD) of 0.1 ng/mL. The photothermal instrument mode (Mode 2) achieved a detection range of 0.1-500.0 ng/mL with an LOD of 0.1 ng/mL. The sensitivity and accuracy of the method were validated using an Enzyme-Linked Immunosorbent Assay. This developed method successfully detected ciprofloxacin residues in samples of Parabramis pekinensis, Larimichthys crocea, Channa argus, Carassius auratus and Micropterus salmoides, with satisfactory recovery rates. The results demonstrated excellent specificity and applicability across various fish product matrices, offering a reliable and efficient solution for the on-site monitoring of ciprofloxacin residues in fish products.

Nanocellulose composites based on embedded europium-containing coordination polymers for the detection of antibiotics

Developing sensitive and reliable methods for detecting antibiotics in water solutions is essential for protecting public health and the environment. Here, we report a novel fluorescent film with superior mechanical properties and detection response to ciprofloxacin (CIP), achieved through the in-situ growth of europium-based metal-organic frameworks on TEMPO-oxidized cellulose nanofibrils (TOCNF). Firstly, Eu(III) and 2,6-pyridinedicarboxylic acid (DPA) served as precursors, and a simple self-assembly strategy was employed to grow the composite film material (Eu-DPA@TOCNF) in situ on TOCNF, which exhibited characteristic emission peaks. Benefiting from the growth balance and control of Eu-DPA by TOCNF, the sensor based on Eu-DPA@TOCNF showed higher stability and practicability, allowing sensitive and selective detection of CIP, with a good linear relationship in the range of 0-200 μM, showing an inverse relationship between the fluorescence intensity at 619 nm and CIP concentration. The quenching mechanism of CIP on Eu-DPA@TOCNF could be attributed to the combined effects of both static and dynamic quenching processes. Consequently, the Eu-DPA@TOCNF fluorescent film provides a novel strategy for developing pollutant detection sensors based on fluorescent specificity.

Preparation of ofloxacin molecularly imprinted polymer Raman sensor based on magnetic graphene oxide

Ofloxacin is a commonly used quinolone antibiotic that is also used as a feed supplement in livestock production and in plant disease prevention and treatment. However, the excessive use and abuse of ofloxacin will accumulate along the food chain and endanger human health. Therefore, the development of a simple, rapid, and sensitive detection method for the determination of ofloxacin is critical. Herein, a detection method combining molecularly imprinted magnetic solid-phase extraction (MISPE) and surface-enhanced Raman spectroscopy (SERS) was developed for the detection of ofloxacin. Graphene oxide supported by magnetic beads was synthesized by a one-pot method, producing what was subsequently referred to as magnetic graphene oxide (MGO), and a molecularly imprinted membrane was synthesized on its surface by exploiting the ability of dopamine to self-polymerize under alkaline conditions. MGO@MIPs were obtained as the adsorbent for magnetic solid-phase extraction, which was used for the extraction and enrichment of ofloxacin in complex sample matrix, and then quantitative analysis was conducted by SERS. The developed method exhibited an excellent linear relationship with respect to ofloxacin concentration (10-5 to 102 μg mL-1), with a detection limit of 9.7 × 10-6 μg mL-1 in ultrapure water. Blank honey, milk, and pork samples spiked with ofloxacin at concentrations of 0.005, 0.1, 1, and 10 μg mL-1 were extracted and determined using the developed method, with recoveries ranging from 93.1% to 105.6%. The results support the strong application prospects for the method, demonstrating simple and time-efficient operation and high accuracy.

Automatic detection of multi-antibiotic residues simultaneously in aquatic products by visual protein microarray chips

A 96-well microplate-based protein microarray chip which can simultaneously detect three different families of antibiotics using a multiplexed approach has been developed for the first time. All steps in the microarray chip can be completed through an automated biochip analyzer, enabling high throughput analysis of 96 samples within 60 min according to the set program. The microarray chip can be visually evaluated by the color depth of array points, and can also be quantified through a scanner. Under the optimal conditions, the limits of detection (LODs) of nitrofuran metabolites (NFMs), chloramphenicol (CAP), and fluoroquinolones (FQs) were 0.11-0.15 μg/kg, 0.07 μg/kg and 6.42 μg/kg, respectively. This microarray chip can be applied to different aquatic products, including crucian carp, shrimp, and scallops, with the recovery ranged from 89.4 % to 111.2 %. These results demonstrate new strategies for the high-throughput detection of multi-antibiotic residues and present potential of protein chip technologies for daily supervision.

Immunoglobulin Y-Based Lateral Flow Immunoassay Strip Test for Detecting Ciprofloxacin Antibiotic in Raw Pork Samples

Ciprofloxacin is metabolized from enrofloxacin for use in poultry to manage respiratory and gastrointestinal diseases, raising concerns due to its widespread tissue distribution and prolonged systemic persistence. This lateral flow immunoassay was designed to detect ciprofloxacin using an alternative IgY antibody binded with gold nanoparticles to detect ciprofloxacin residue in raw pork meat samples. The developed strip test achieved adequate sensitivity and specificity under the optimized conditions for pH, which is 7.8, and 20% of MeOH in 0.01 M phosphate buffer containing 1% Tween-20 was used for the buffer composition. An antibody concentration of 1.25 µg/mL was used to bind with gold nanoparticles as a probe for detection. The concentration of the test line (coating antigen) and control line (anti-IgY secondary antibody) was 0.5 mg/mL and 0.2 mg/mL, respectively. The efficiency of the developed strip test showed sensitivity with a 50% inhibitory concentration (IC50) of ciprofloxacin at 7.36 µg/mL, and the limit of detection was 0.2 µg/mL. The proposed strategy exhibited potential for monitoring ciprofloxacin in raw pork samples.

Development of a Colloidal Gold Immunochromatographic Assay Strip Using a Monoclonal Antibody for the Rapid Detection of Ofloxacin

The livestock industry uses ofloxacin, an antibiotic, to prevent several animal diseases; however, the overdose of ofloxacin used in animal farming treatments may appear in food products and cause some adverse human health effects. Hence, there is an immediate need to develop a method suitable for on site large-scale detection of ofloxacin residues in animal-derived foods. This study aimed to prepare a monoclonal antibody with high sensitivity and affinity for ofloxacin by re-synthesizing the ofloxacin hapten and synthesizing the corresponding complete antigen. The IC50 of the enzyme-linked immunosorbent assay (ic-ELISA) was 0.13 ng/mL, and the detection limit was 0.033 ng/mL. The visual detection limit of the established colloidal gold immunochromatographic test strip, for the visual detection of actual samples, was 1 ng/g. In summary, this work establishes a rapid detection method of ofloxacin residues on the basis of colloidal gold immunochromatography that is suitable for actual detection.

Development of a new synchronous fluorescence spectrometry combined with Al3+ sensitized for simultaneous and rapid determination of trace flumequine, ciprofloxacin and doxycycline hydrochloride residues in wastewater

Antibiotics are a new type of environmental pollutants. Due to its wide application in many fields, antibiotic residues are ubiquitous in the wastewater environments. Given their potential threat on water ecosystem functioning and public health, the detection of antibiotic residues in wastewater environments has become very necessary. Based on the complexation of Al3+ with flumequine (FLU), ciprofloxacin (CIP) and doxycycline hydrochloride (DOX), their molecular conjugated area were increased and fluorescence intensity were enhanced, combined with synchronous fluorescence spectrometry (SFS) had good selectivity and high sensitivity, a novel method of Al3+ sensitized synchronous fluorescence spectrometry for the determination of FLU, CIP and DOX residues in wastewater was established. When the wavelength difference (Δλ) was selected 115.0 nm, synchronous fluorescence spectra of the three antibiotics could be well separated and the interference of wastewater matrix were eliminated primely. The new SFS made good use of spectral separation instead of conventional chemical separation, and the actual wastewater sample could be directly determined after simple filtration. The experiment results showed that the concentrations of FLU, CIP and DOX in the range of 0.5000-800.0 ng·mL-1, 0.5000-640.0 ng·mL-1 and 10.00-3500 ng·mL-1 had a good linear relationship with fluorescence intensity. The detection limits of three antibiotics were 0.02054 ng·mL-1, 0.03956 ng·mL-1 and 0.8524 ng·mL-1, respectively. Recovery rates of three antibiotics in wastewater samples were 90.72%-98.23%, 88.68%-95.08% and 85.94%-96.70%. The new SFS established in this experiment had the advantages of simple, rapid, sensitive, accurate and good selectivity. Simultaneous and rapid detection of FLU, CIP and DOX residues in wastewater was successfully realized. It had good application prospects in real-time water quality monitoring.

Advancements and greenification potential of magnetic molecularly imprinted polymers for chromatographic analysis of veterinary drug residues in milk

Milk, as a widely consumed nutrient-rich food, is crucial for bone health, growth, and overall nutrition. The persistent application of veterinary drugs for controlling diseases and heightening milk yield has imparted substantial repercussions on human health and environmental ecosystems. Due to the high demand, fresh consumption, complex composition of milk, and the potential adverse impacts of drug residues, advanced greener analytical methods are necessitated. Among them, functional materials-based analytical methods attract wide concerns. The magnetic molecularly imprinted polymers (MMIPs), as a kind of typical functional material, possess excellent greenification characteristics and potencies, and they are easily integrated into various detection technologies, which have offered green approaches toward analytes such as veterinary drugs in milk. Despite their increasing applications and great potential, MMIPs' use in dairy matrices remains underexplored, especially regarding ecological sustainability. This work reviews recent advances in MMIPs' synthesis and application as efficient sorbents for veterinary drug extraction in milk followed by chromatographic analysis. The uniqueness and effectiveness of MMIPs in real milk samples are evaluated, current limitations are addressed, and greenification opportunities are proposed. MMIPs show promise in revolutionizing green analytical procedures for veterinary drug detection, aligning with the environmental goals of modern food production systems.

Enhanced Molecularly Imprinted Fluorescent Test Strip for Rapid and Visual Detection of Norfloxacin via a Smartphone

Paper-based test strips with on-site visual detection have become a hot spot in the field of target detection. Yet, low specific surface area and uneven deposition limit the further application of test strips. Herein, a novel "turn-on" ratio of molecularly imprinted membranes (Eu@CDs-MIMs) was successfully prepared based on a Eu complex-doped polyvinylidene fluoride membrane for the selective, rapid and on-site visual detection of norfloxacin (NOR). The formation of surface-imprinted polymer-containing carbon dots (CDs) improves the roughness and hydrophilicity of Eu@CDs-MIMs. Fluorescence lifetimes and UV absorption spectra verified that the fluorescence enhancement of CDs is based on the synergistic effect of charge transfer and hydrogen bonding between CDs and NOR. The fluorescent test strip showed a linear fluorescent response within the concentration range of 5-50 nM with a limit of detection of 1.35 nM and a short response time of 1 min. In comparison with filter paper-based test strips, Eu@CDs-MIMs exhibit a brighter and more uniform fluorescent color change from red to blue that is visible to the naked eye. Additionally, the applied ratio fluorescent test strip was combined with a smartphone to translate RGB values into concentrations for the visual and quantitative detection of NOR and verified the detection results using high-performance liquid chromatography. The portable fluorescent test strip provides a reliable approach for the rapid, visual, and on-site detection of NOR and quinolones.