Magnetic Fe3O4@COF@Ag SERS substrate combined with machine learning algorithms for detection of three quinolone antibiotics: Ciprofloxacin, norfloxacin and levofloxacin

Quinolone antibiotics have good antibacterial properties and are commonly used antibiotics in the dairy industry. Currently, the problem of excessive antibiotics in dairy products is very serious. As an ultra-sensitive detection technology, Surface-Enhanced Raman Scattering (SERS) was applied to the detection of quinolone antibiotics in this work. In order to classify and quantify three antibiotics (Ciprofloxacin, Norfloxacin, Levofloxacin) with highly similar molecular structures, a combination of magnetic COF-based SERS substrate and machine learning algorithms (PCA-k-NN, PCA-SVM, PCA-Decision Tree) was used. The classification accuracy of the spectral dataset could reach 100% and the results of LOD calculation were: CIP: 5.61 × 10^-9M, LEV: 1.44 × 10^-8M, NFX: 1.56 × 10^-8M. This provides a new method for the detection of antibiotics in dairy products.

Application of Au@Pt Nanozyme as Enhancing Label for the Sensitive Lateral Flow Immunoassay of Okadaic Acid

In this study, a lateral flow immunoassay (LFIA) was developed to detect okadaic acid (OA) belonging to the diarrheic shellfish poisoning group of aquatic toxins. Newly obtained anti-OA monoclonal antibodies and bimetallic core@shell Au@Pt nanoparticles were used in the indirect format of the LFIA. Peroxidase-mimicking nanozyme properties of Au@Pt enabled using them to enhance band coloration on the test strips and, consequently, for increasing the LFIA sensitivity. The instrumental limit of detection (LOD), the working range of detectable concentrations, and the visual cutoff of the assay were 0.5, 0.8-6.8, and 10 ng/mL, respectively. The assay duration was 20 min. The rapid and simple sample preparation procedure was applied for seawater, river water, and fish samples. The total duration of the sample pretreatment and LFIA was 25/40 min for water/fish samples, ensuring testing rapidity. The developed test system provides sensitive control of raw materials and food products and can be used to detect OA at all stages of the food industry «from sea to fork» chains.

Triple immunochromatographic test system for detection of priority aquatic toxins in water and fish

Aquatic toxins are a group of toxic compounds produced by several types of freshwater and marine algae and cyanobacteria and transported through the food chains of water bodies. Potential contamination of aquaculture products (raw and processed fish and seafood) with aquatic toxins requires the use of efficient screening methods for their control. In this study, a multiplex immunochromatographic test system for the simultaneous detection of three aquatic toxins-phycotoxins domoic acid (DA) and okadaic acid (OA), and cyanotoxin microcystin-LR (MC-LR)-is for the first time developed. For this, a competitive indirect immunochromatographic analysis (ICA) based on gold-labeled secondary antibodies was carried out. The LODs/cutoffs/working ranges of the ICA were 0.05/0.3/0.07-0.29, 1.3/100/3.2-58.2, and 0.1/2.0/0.2-1.1 ng/mL for MC-LR, DA, and OA, respectively. The assay duration was 18 min. The developed test system was used to analyze water samples from natural sources (salt and fresh water) and fish samples. For sample preparation of water, simple dilution with a buffer was proposed; for fish samples, methanol-water extraction was utilized. It was demonstrated that the triple LFIA specifically detected target aquatic toxins with recoveries of 85.0-121.5%. The developed multiplex LFIA can be considered a promising analytical solution for the rapid, easy, and sensitive control of water and food safety.

Double Immunochromatographic Test System for Sensitive Detection of Phycotoxins Domoic Acid and Okadaic Acid in Seawater and Seafood

In this investigation, a double immunochromatographic analysis (ICA) of two relevant phycotoxins, domoic acid (DA) and okadaic acid (OA), was developed for the first time. The ICA was performed in the indirect competitive format using gold nanoparticles conjugated with anti-species antibodies. Under optimal conditions, the instrumental detection limits/cutoffs for simultaneous detection of DA and OA were 1.2/100 and 0.1/2.5 ng/mL, respectively. The time of the assay was 18 min. The ICA was applied to test seawater and a large panel of seafood, including mussels, tiger shrimps, octopuses, whelks, crabs, and scallops. The proposed simple sample preparation method for seafood takes only 20 min. For seawater, a dilution by buffer was implemented. The assay recoveries varied from 80.8% to 124.5%. The competitive potential of the proposed technique as a tool to control natural water and seafood samples is determined by its simplicity, rapidity, and sensitivity.

Rapid detection of phycotoxin domoic acid in seawater and seafood based on the developed lateral flow immunoassay

A lateral flow immunoassay (LFIA) of phycotoxin domoic acid (DA) contaminating seawater and marine organisms was developed in this investigation. Nine clones of monoclonal antibodies against DA were produced and characterized. The test system was implemented in the indirect competitive format, where gold nanoparticles as a marker were conjugated with secondary antibodies. The developed test system allows for the detection of DA with a cutoff of 60 ng mL^-1 and an instrumental detection limit of 1.4 ng mL^-1 within 15 min. The LFIA was applied to detect DA in seawater, mussels, shrimps, and octopuses. A simple method of seafood sample preparation was proposed. The entire analytical cycle, from obtaining a sample to the estimation of final results, takes only 30 min. The assay recoveries ranged from 88.5% to 124%. The developed analytical method is a promising solution for rapid on-site monitoring of marine toxicants in water and food throughout the farm-to-fork chain.

In-situ dual effect of Ag-Fe-TiO2 composite for the photocatalytic degradation of Ciprofloxacin in aqueous solution

Industrial waste materials such as Fly Ash (FA), Foundry Sand (FS) were used as support material by mixing them with clay to fix the catalyst. Where FA and FS served as an iron (Fe) source to induce the photo-Fenton process. The presence of Fe in FA and FS was affirmed by SEM-EDS characterization. UV-DRS was performed to analyze the bandgap of the composite which reduced from 2.96 to 2.82 eV after doping TiO2 with Ag. This composite was used to initiate photocatalysis. The fixing of catalyst on a support formed the Fe-Ag-TiO2 complex which led to the commencement of the in-situ dual process(i.e. photocatalysis and photo-Fenton) in fixed bed mode. After the optimization of several parameters such as H₂O₂ dose, the area covered by beads, A/V ratio, Flow rate, pH under solar irradiations for 60 min, 94.4% degradation of CIP was attained. XRD analysis was carried out to confirm the crystallographic phases of the composite anatase and rutile phases of TiO₂ were present in the composite. The systematic leaching of iron took place in this process and was confirmed by iron estimation during the reaction process. To understand the elemental composition of the composite SEM-EDS was performed and the present of TiO₂, Fe and Ag was affirmed. Composite beads were stable and active even after the 30 recycles as confirmed by SEM-EDS. The intermediate products were analyzed by GC-MS analysis whereas the toxicity of the treated samples was studied by the zone inhibition test.

Tailor-Made Immunochromatographic Test for the Detection of Multiple 17α-Methylated Anabolics in Dietary Supplements

In recent years, the undeclared presence of various anabolic androgenic steroids (AAS) in commercial supplements has been confirmed. This fact can be a potential threat to all athletes using these supplements, and therefore, there is of increased interest in the implementation of rapid methods for the detection of AAS. The presented study describes the development of an immunostrip test for the detection of multiple 17α-methylated AAS based on direct and indirect competitive principle using gold nanoparticles as a label. As a capture reagent on test lines conjugated stanazolol to rabbit serum albumin (RSA/ST-3) was used, the intensity of color formed in the test line of the AAS-positive sample was visually distinguishable from that of negative sample within 10 min. The optimized closed direct and indirect format of the test provided a similar visual detection limit (0.7 and 0.9 ng/mL, respectively). The most commonly orally abused AAS (17α-methyltestosterone, methandienone, methyldihydrotestosterone, oxandrolone and oxymetholone) showed a strong cross-reaction. Developed immunostrips were successfully applied to analysis of artificially contaminated dietary supplements with 17α-methylated AASs. The developed immunostrips offer potential as a useful user-friendly method for capturing suspicious dietary supplement samples with different contents of AAS at levels far below the usually used concentrations of AAS.

Development of immunochromatographic strips for the detection of dicofol

In this study, a monoclonal antibody (mAb) against dicofol was developed to prepare immunochromatographic strips (ICAs) for the detection of dicofol residues in fruit and vegetables. The mAb exhibited high affinity and high sensitivity, with an affinity constant of 2.96 × 10¹⁰ and a limit of detection of 3.142 ng mL^-1. A cross reactivity test revealed that the mAb also had good specificity for dicofol. This ICA method gave a visible limit of detection of 50 ng g^-1, and a cut-off value of 500 ng g^-1 for the detection of dicofol in both apple and cucumber with the naked eye. Importantly, the results here are consistent with results obtained using liquid chromatography mass spectrometry and ic-ELISAs indicating that this ICA method is reliable and practical when used for the detection of dicofol in fruit and vegetables.

A Comparative Study of Approaches to Improve the Sensitivity of Lateral Flow Immunoassay of the Antibiotic Lincomycin

This study provides a comparative assessment of the various nanodispersed markers and related detection techniques used in the immunochromatographic detection of an antibiotic lincomycin (LIN). Improving the sensitivity of the competitive lateral flow immunoassay is important, given the increasing demands for the monitoring of chemical contaminants in food. Gold nanoparticles (AuNPs) and CdSe/ZnS quantum dots (QDs) were used for the development and comparison of three approaches for the lateral flow immunoassay (LFIA) of LIN, namely, colorimetric, fluorescence, and surface-enhanced Raman spectroscopy (SERS)-based LFIAs. It was demonstrated that, for colorimetric and fluorescence analysis, the detection limits were comparable at 0.4 and 0.2 ng/mL, respectively. A SERS-based method allowed achieving the gain of five orders of magnitude in the assay sensitivity (1.4 fg/mL) compared to conventional LFIAs. Therefore, an integration of a SERS reporter into the LFIA is a promising tool for extremely sensitive quantitative detection of target analytes. However, implementation of this time-consuming technique requires expensive equipment and skilled personnel. In contrast, conventional AuNP- and QD-based LFIAs can provide simple, rapid, and inexpensive point-of-care testing for practical use.

Lateral flow immunoassay for sensitive detection of undeclared chicken meat in meat products

This study presents the development of an immunochromatographic test system aimed at the detection of chicken additives in meat products. It is based on sandwich-format lateral flow immunoassay (LFIA) of immunoglobulins as a biomarker for species identification. The LFIA based on gold nanoparticles as a label for anti-species antibodies was used to determine chicken immunoglobulins and, accordingly, chicken meat in food products. Absence of cross-reactivity with mammalian species tested in the study confirmed high specificity of the determination. The test system showed good sensitivity and rapidity, allowing for the detection of as low as 0.063% (w/w) chicken meat in raw meat mixtures within 20 min. As a result of the testing of raw and cooked meat products, it was shown that the test system can reliably recognize specific immunoglobulins even after heat processing. The proposed assay can be recommended for rapid on-site screening control of the composition and quality of meat products.

Sensitive lateral flow immunoassay of an antibiotic neomycin in foodstuffs

Aminoglycosides belong to a class of antibiotics now widely used in agriculture and veterinary medicine and expected to contaminate food products. In this study, a sensitive lateral flow immunoassay (LFIA) of an aminoglycoside neomycin (NEO) was developed. Two methods of immunochromatographic detection based on various techniques of gold nanoparticles (AuNPs) introduction as a label were compared. It was demonstrated that the indirect labeling (a conjugation of anti-species antibodies with a marker) allowed for an increase in assay sensitivity by 80 times. The test system was characterized by an instrumental limit of detection of 0.1 ng/mL and the cutoff level of 10 ng/mL; the assay duration was 15 min. Specificity only toward NEO was demonstrated. The developed LFIA has been tested to detect NEO in different foodstuffs. It has been demonstrated that 70-119% of NEO (coefficients of variations < 10%) can be determined in milk, turkey meat, honey, and eggs using simple procedures of preliminary sample preparation. Testing the samples showed the coincidence of the results for the developed lateral flow assay and for commercial ELISA kit.

Development of a double immunochromatographic test system for simultaneous determination of lincomycin and tylosin antibiotics in foodstuffs

This study is devoted to the development of a sensitive immunochromatographic analysis (ICA) for simultaneous determination of tylosin (TYL) and lincomycin (LIN) as antibiotics of the macrolide and lincosamide classes, widely used in animal husbandry and implicated in the contamination of foodstuffs. The ICA was implemented in an indirect competitive format, using antispecies antibodies conjugated with gold nanoparticles (GNPs) as a label. After the multistep optimization, the developed double ICA allowed for antibiotics detection with instrumental limits of detection/cutoff levels of 0.09/2 ng/mL and 0.008/0.8 ng/mL for TYL and LIN, respectively, within 10 min. The cross-reactivity was 40% to lincosamide clindamycin and negligible to other antibiotics tested. The test system allowed for the detection of TYL and LIN in milk, honey, and eggs. The recoveries of antibiotics from foodstuffs were 87.5-112.5%. The results demonstrate that the developed double ICA is an effective approach for the detection of other food contaminants.

An immunochromatographic test system for the determination of lincomycin in foodstuffs of animal origin

The aim of this study was to develop a rapid and sensitive immunochromatographic test system for the detection of lincomycin (LIN), which belongs to the lincosamide group of antibiotics and contaminates food products of animal origin. Two formats of immunochromatographic analysis (ICA) based on different approaches of introducing gold nanoparticles (GNPs) as a label were compared. It was demonstrated that an indirect ICA method where GNPs were conjugated with anti-species antibodies allowed the achievement of both instrumental and visual detection limits of LIN almost two orders of magnitude lower than those achieved in the standard direct ICA format. In the optimized conditions, the developed indirect ICA allowed for the detection of LIN within 15 min, with instrumental and visual detection limits of 8 pg/mL and 0.8 ng/mL. The assay showed 40% cross-reactivity to clindamycin (CLIN) as a structural analogue of LIN, with no interaction with antibiotics from other classes. The developed ICA was applied for LIN detection in a panel of food products. No treatment of cow milk was necessary before the analysis. For chicken eggs and honey, a simple procedure of preliminary sample preparation was developed, which fully prevented a matrix influence on the assay results. It was demonstrated that ICA could detect LIN in food products while preserving the same analytical characteristics as in the buffer. The analytical recoveries of LIN in foodstuffs were 93.8-125% with coefficients of variations of 5.3-14.0%.

Development of a multicomponent immunochromatographic test system for the detection of fluoroquinolone and amphenicol antibiotics in dairy products

BACKGROUND

Ciprofloxacin (CIP) and chloramphenicol (CAP) are relevant antibiotics of the fluoroquinolone (FQ) and amphenicol (AP) groups, respectively, widely used in veterinary practice and they contaminate agricultural products. In this study, a rapid and sensitive immunochromatographic assay (ICA) was developed for simultaneous detection of CIP and CAP in dairy products. The ICA was carried out in a direct competitive format using gold nanoparticles as a label.

RESULTS

The ICA developed here allowed for the detection of CIP and CAP in Triton X-100-containing buffered saline (PBST) within 15 min with instrumental detection limits of 20 pg mL^-1 and 0.5 ng mL^-1 , respectively, and with a visual detection limit of 5 ng mL^-1 for both antibiotics. The ICA showed cross-reactivity (69-160%) to 19 antibiotics in the FQ group and no cross-reactivity (<0.1%) to 2 antibiotics of the AP group. The ICA allowed detection of CIP and CAP in a panel of dairy products by employing a simple procedure of preliminary sample preparation. The detection limits for the two antibiotics were the same as in PBST. The analytical recoveries of CIP and CAP in dairy products ranged from 83% to 120%.

CONCLUSION

The analytical characteristics of the test system allow its use for the detection of antibiotics in milk and dairy products during all steps of production. © 2019 Society of Chemical Industry.