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The compound 2,4-dichlorophenoxyacetic acid (2,4-D) is a synthetic plant growth regulator, which is widely used in agricultural production. Consequently, it is necessary to establish a rapid and sensitive detection method to monitor its use and prevent the environmental and human health problems caused by overuse. In this study, a monoclonal antibody (mAb) 2D5 against 2,4-D was prepared, and based on it, an ic-ELISA and an immunochromatographic strip assay (ICA) were developed for rapid detection. The 50% inhibitory concentration (IC 50 ) of the mAb against 2,4-D was 1.7 ng mL -1 and the mAb showed no cross-reactivity with other plant growth regulators with similar structures to 2,4-D. Under optimum conditions, the ICA showed a visual detection limit (vLOD) of 20 ng mL -1 and a cut-off value of 200 ng mL -1 in bean sprouts, and cabbage samples gave the same results. The quantitative detection showed the linear detection ranges for bean sprouts and cabbage samples were 6.3-73.0 and 5.4-132.6 ng mL -1 , respectively. The ICA was successfully applied to detect 2,4-D in bean sprouts and cabbage samples and achieved good recoveries ranging from 94.7% to 104.3% with a coefficient of variation (CV) less than 8.3%. Hence, the ICA provides a sensitive, efficient and reliable detection method, which has broad application prospects in the detection of a large number of samples., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

We developed a sensitive and rapid lateral flow immunochromatographic (LFI) assay for the simultaneous detection of fipronil and its metabolites in eggs and cucumbers using gold nanoparticle (GNP)-labeled monoclonal antibodies (mAbs). Anti-fipronil mAbs (1B6) were produced using two haptens and identified by heterologous indirect competitive enzyme-linked immunosorbent assay (icELISA) with half maximal inhibitory concentration (IC 50 ) and limit of detection (LOD) values of 0.46 ± 0.07 and 0.05 ± 0.01 ng mL -1 , respectively. The developed LFI strip showed high sensitivity and specificity in the detection of fipronil with cut-off and visual limit of detection (vLOD) values of 10 and 0.25 ng mL -1 , respectively. Furthermore, the application of LFI in the detection of fipronil-spiked egg and cucumber samples was validated by liquid chromatography tandem mass spectrometry (LC-MS/MS). Our developed LFI assay is suitable for detection of fipronil and its metabolites in real samples., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Because of increasing levels of obesity and the development of social network platforms, the online sale of slimming beverages has become very common. However, such beverages are often reported to contain hazardous drugs, such as phenolphthalein. In the present study, we established a rapid and sensitive immunochromatography gold-labeled monoclonal antibody (mAb) (IGM) method and a fluorescence-labeled mAb (IFM) method for determining phenolphthalein in ten types of slimming tea. The monoclonal antibodies and coating antigens were produced in our laboratory. Under optimal conditions, the cut-off limits were 250 ng mL-1 (IFM strip) and 500 ng mL-1 (IGM strip) in both 0.01 M phosphate-buffered saline (PBS) and samples of slimming tea. The mean recoveries were 96.2 to 104.7% for the IGM strip and 90.7 to 104.7% for the IFM strip. The data showed that the IFM strip was more sensitive than the IGM strip and that results could be generated within 10 min. Consequently, this novel technique represents a rapid and convenient method with which to detect phenolphthalein.

Tadalafil (TDL) is an illegal additive drug found in drinks and functional foods that could threaten public health. There was a great concern whether the adulteration occurred in coffee added with similar type of herbs. Here we have developed a rapid, simple, sensitive, and semi-quantitative lateral flow immunoassay (LFIA) based on gold and fluorescence labelled monoclonal antibody (mAb) for detection of TDL in coffee sample. Under optimal conditions, the cut off limits using gold nanoparticles labelled mAb (GLM) was found to be 250 ng/mL and 100 ng mL using fluorescent labelled mAb (FLM) in coffee samples. The coffee samples were spiked with TDL, and the LFIA with GLM gave average recoveries of 92-105.3% (intra-assay) and 96.6-105.9% (inter-assay), meanwhile with FLM gave recoveries 97.9-107.3% (intra-assay) and 98.3-108.9% (inter-assay). Results gave LFIA with FLM more sensitive than with GLM and all the test can be completed within 10 min, which would be an option for convenient and rapid assay of TDL detection., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

In this study, the monoclonal antibody-based indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and an immunochromatographic strip assay were developed for the rapid screening of robenidine hydrochloride (ROBH) in samples. The 50% inhibitory concentration (IC 50 ) of ROBH was 0.927 ng mL -1 , and the standard curve showed a linear correlation coefficient of 0.99932. There was no cross-reaction between ROBH and other commonly used anticoccidial drugs, which indicated that the monoclonal antibody had high specificity. The recoveries of ic-ELISA were in the range of 87.8% to 102.0%. The immunochromatographic strip assay displayed cut-off values of 10, 5 and 10 ng g -1 for shrimp, chicken breast and chicken liver samples, respectively. In addition, the results can be obtained within 10 min by naked eye observations. And in sample analysis, the results of ic-ELISA and the immunochromatographic strip assay were in accordance with those of LC-MS/MS. Thus, the ic-ELISA and immunochromatographic strip assay are effective methods for the detection of ROBH in shrimp, chicken breast and chicken liver samples.

In this study, a gold immunochromatographic assay (GICA) based on a penicillin receptor protein (PBP) is proposed to simultaneously detect penicillin, cephalosporin, and carbapenem antibiotics in milk and chicken. A mutant PBP, carboxy-terminal of the β-lactam sensor-transducer protein (BlaR-CTD, I188KS19CG24C) from Bacillus licheniformis ATCC14580 was expressed in E. coli as a soluble His-tag fusion protein. The purified BlaR-CTD mutant was labeled with colloidal gold (CG-BlaR-CTD-M) and applied to develop GICA. The GICA method was performed based on a competitive form, where the binding of the ampicillin-bovine serum albumin conjugate (Amp-BSA) to CG-BlaR-CTD-M was inhibited by free β-lactams in samples. The performance of the assay was confirmed by analysis of milk and chicken samples. The limits of detection of 21 β-lactam antibiotics met the maximum residue limits set by the European Union and China. The GICA gave results within 10 min, thus providing a rapid and reliable method for the on-site detection of multiple β-lactams in milk and chicken samples.

Paraquat (PQ) poisoning is a serious threat to human health that leads to pulmonary toxicity, neurotoxicity, and inflammation. Protecting humans from PQ exposure requires the development of rapid analytical methods for on-site detection. Here, two monoclonal antibodies against PQ were generated and an immunochromatographic assay (ICA) was exploited to determine PQ concentrations in water samples. The results showed that the monoclonal antibody 1D6 exhibited higher affinity and sensitivity, with an affinity constant of 5.4 × 10 8  mol/L and a limit of detection as low as 0.02 ng/mL. Without sample pretreatment, the developed ICA method provided visible limits of detection ranging from 0.25 to 1 ng/mL, and cut-off limits ranging from 1 to 5 ng/mL, where average recoveries were between 83.15% ± 1.9% and 94.49% ± 2.45% with a coefficient of variation ranging from 1.40% to 7.37%. Importantly, these observations were consistent with liquid chromatography tandem mass spectrometry. These data and results suggested that the ICA method was a reliable, portable, and high-throughput method for determining PQ residues in water samples., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

In this study, haptens were designed to produce highly sensitive and specific monoclonal antibodies (mAb) against carbamazepine (CBZ) and its metabolite carbamazepine-10, 11-epoxide (CBZ-EP). According to the results of our competitive enzyme-linked immunosorbent assay (ic-ELISA), the half-maximum inhibitory concentration values for anti-CBZ and anti-CBZ-EP mAb were 0.18 and 0.59 ng/mL, respectively. An immunochromatographic assay (ICA) was developed for the determination of CBZ and CBZ-EP concentrations. This method can provide visible limits of detection ranging from 0.25 to 1 ng/mL, and cut-off limits ranging from 5 to 10 ng/mL, and takes 10 min to evaluate with the naked eye. Importantly, these observations were consistent with those obtained by ic-ELISA and liquid chromatography-mass spectrometry. The ICA assay represented a reliable, fast, and high-throughput method for the determination of CBZ and CBZ-EP in serum samples., Competing Interests: Declaration of Competing Interest The authors declare no competing financial interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

A monoclonal antibody (mAb) against vitamin B1 was prepared and based on this, an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and colloidal gold-based immunochromatographic test (ICT) strip were developed. The 50% inhibition concentration (IC50) and the limit of detection (LOD) for the developed ic-ELISA were estimated to be 20.71 ng mL-1 and 4.51 ng mL-1 in the assay buffer. Vitamin B1 in energy drinks, vitamin tablets, and infant milk powder samples was detected by the developed ic-ELISA and the average recoveries ranged from 80.63% to 103.05%. The vitamin B1 content in energy drinks, vitamin tablets, and infant milk powder samples were confirmed by using liquid chromatography tandem mass spectrometry (LC-MS/MS). Moreover, the cut-off value of the developed ICT strip assay was 250 ng mL-1, with a LOD value of 5.33 ng mL-1. Real samples were used to validate the reliability of the developed ICT strip. All results demonstrated that our developed methods are suitable for the detection of vitamin B1 in food and pharmaceutical products.

Cyclopiazonic acid (CPA) is an indole-tetramine mycotoxin commonly produced by Penicillium and Aspergillus and is widely found in agricultural products, fermented food, and feed. Food contaminated with CPA poses a substantial health risk to consumers. Therefore, eco-friendly immunoassays, including an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and a lateral flow immunochromatographic strip (LFICS), were developed to monitor CPA in maize and rice samples. For this purpose, a monoclonal antibody (3H12) posed highly resistant to pH (5.6 to 9.6) and ethanol (≤50%) was generated by mouse immunization. Negative maize and rice samples or samples spiked with CPA were extracted with ethanol/0.01 M sodium borate buffer (4/1, v/v, pH 8.4). For ic-ELISA analysis, the limits of detection (LODs) were 0.48 and 0.28 ng/g for maize and rice samples, respectively. The recovery for spiked maize was 76.9% to 83.5% with the highest variable coefficient (CV max ) being 9.32%. For spiked rice, the recovery was 85.3% to 105.1% with a CV max of 8.56%. For LFICS analysis, the visible LODs were 2.5 and 1 ng/g and cutoff values were 5 and 2.5 ng/g for maize and rice samples, respectively. The LFICS method gave results within 5 to 10 min, providing an auxiliary analytical tool for the rapid, sensitive, and portable screening of the massive samples onsite., (© 2019 Institute of Food Technologists®.)

Lincosamides (LMs), include clindamycin (CLIN), lincomycin (LIN), and pirlimycin (PIR), that are widely used as veterinary drugs. LM residues in edible animal origin foods endanger human health and are in urgent need of establishing fast, simple, and highly sensitive detection methods. A gold immunochromatographic strip is prepared to detect CLIN, LIN, and PIR residues simultaneously with a single monoclonal antibody. This antibody is obtained with the design of a novel Hapten and can simultaneously recognize CLIN, LIN, and PIR. Under optimized conditions, the strip results can be semi-quantitatively evaluated with the naked eye within 15 min, with cut-off values in phosphate-buffered saline of 1 ng mL -1 for CLIN, 10 ng mL -1 for LIN, and 25 ng mL -1 for PIR, respectively. Besides, the strip can also be quantified using a hand-held strip scanner, and the spiked samples are used for establishing matrix curves. The limits of detection for CLIN, LIN, and PIR in spiked milk, egg, beef, and honey samples can satisfy the detection requirement. The utility of this strip is also confirmed by positive honey sample. In short, this strip should be expected to be a useful tool for the rapid on-site screening of lincosamide residues in milk, egg, beef, and honey samples., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In this study, a carboxyl group was introduced into the isoprocarb molecule to obtain an isoprocarb hapten, which was then coupled with a protein to obtain an artificial antigen. Three monoclonal antibody cell lines, 1D11, 6E6 and 1B5, were finally obtained by mouse immunization, cell fusion and subcloning, and the antibody produced by cell line 1B5 had the best affinity and sensitivity. The monoclonal antibody was highly sensitive and specific for isoprocarb, with an IC 50 of 2.09 ng/ml and a cross-reactivity rate of <0.21%. By optimizing the indirect competitive (ic)-ELISA, the optimal conditions were determined to be pH 7.4, 0% methanol and 0.8% NaCl, the limit of detection value was 0.23 ng/ml, and the linear range of the ic-ELISA was 0.46-9.62 ng/ml. The recovery rate of the isoprocarb cucumber sample was 97-99% for the ic-ELISA method. In addition, we successfully developed an immunochromatographic test strip for the detection of isoprocarb residues. The cutoff values in phosphate-buffered saline and cucumber extract were 10 and 25 ng/ml, respectively. Both methods met the requirements for isoprocarb residue detection in agricultural products, and can be used for semiquantitative and qualitative analysis of isoprocarb in vegetables., (© 2019 John Wiley & Sons, Ltd.)

A colloidal gold immunochromatographic assay based on a generic monoclonal antibody is developed for the simultaneous detection of benzimidazoles and metabolite residues in milk samples. The monoclonal antibody is prepared using 2-(methoxycarbonylamino)-3H-benzimidazole-5-carboxylic acid as the hapten, and it can recognize 11 types of benzimidazoles simultaneously. The immunochromatographic strip is assembled and labeled using gold nanoparticles. This strip can detect 11 benzimidazoles including albendazole, albendazole s-oxide, albendazole sulfone, fenbendazole, fenbendazole sulfone, flubendazole, mebendazole, parbendazole, oxfendazole, oxibendazole, and carbendazim within 15 min in milk samples. Results are obtained visually with the naked eye, and the cutoff values and the visual limit of detection values for these benzimidazoles are 25, 6.25, 12.5, 12.5, 50, 25, 50, 50, 50, 6.25, and 25 ng mL -1 , and 6.25, 3.125, 3.125, 1.56, 12.5, 6.25, 12.5, 12.5, 6.25, 0.78, and 12.5 ng mL -1 , respectively. Results are also obtained using a hand-held strip scan reader, with calculated limit of detection values for these benzimidazoles of 0.83, 0.77, 1.83, 0.98, 7.67, 3.50, 3.96, 5.71, 0.92, 0.59, and 1.69 ng mL -1 , respectively. In short, the developed paper sensor is a useful tool for rapid and simple screening of residues of benzimidazoles in milk samples., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

An indirect competitive enzyme-linked immunosorbent assay (icELISA) and an immunochromatographic strip assay using a highly specific monoclonal antibody, were developed to detect methyltestosterone (MT) residues in animal feed. The optimized icELISA had a half-inhibition concentration value of 0.26 ng/mL and a limit of detection value of 0.045 ng/mL. There was no cross-reactivity with eight analogues, revealing high specificity for MT. Based on icELISA results, the recovery rate of MT in animal feed was 82.4%-100.6%. The results were in accordance with those obtained by gas chromatography-mass spectrometry. The developed immunochromatographic strip assay, as the first report for MT detection, had a visual cut-off value of 1 ng/mL in PBS, 2.5 ng/g in fish feed, and 2.5 ng/g in pig feed. Therefore, these immunoassays are useful and fast tools for MT residue detection in animal feed.

A rapid, simple, sensitive, and specific immunochromatographic test strip was developed for the detection of Pantoea stewartii subsp. stewartii (Pss) in corn seed which was soaked overnight and then centrifuged for precipitate re-dissolved as samples. A pair of sensitive monoclonal antibodies for the immunochromatographic test strip was generated by mice immunization and cell fusion. Under optimized conditions, the lower detection limit of the strips for Pss was 1 × 10(5) cfu/mL both in 0.01 M phosphate buffer solution and corn seed samples, with no cross-reactivity with other common plant pathogens. The developed strip is useful and rapid for the detection of Pss in corn seed samples.

A monoclonal antibody specifically recognizing dibutyl phthalate (DBP) was prepared based on a hapten (di-n-butyl-4-aminophthalate). After optimizing various parameters such as concentrations of antibody, coating antigen and composition of the assay buffer, an inhibition curve was plotted with the 50% inhibition concentration value (IC50) 33.6 ± 2.5 ng/mL. A low level of cross-reactivity (<5%) was found for other phthalate esters. Recovery tests were conducted using liquor simulant (a mixture of water and ethanol) at two fortification levels (100 ng/mL and 300 ng/mL). The recovery rates ranged from 84.7% to 94.5% with a coefficient of variation between 7.1% and 12.8%. Nine liquor samples of different alcoholic strengths were detected using the proposed measure and confirmatory analysis was performed using liquid chromatography-mass spectroscopy (LC-MS). The detection results showed good consistency between the two measures and all the data above indicated that the proposed ELISA could be applied in DBP screening.

In this study, we have first developed a rapid and sensitive strip immunosensor based on two heterogeneously-sized gold nanoparticles (Au NPs) probes for the detection of trace lead ions in drinking water. The sensitivity was 4-fold higher than that of the conventional LFA under the optimized conditions. The visual limit of detection (LOD) of the amplified method for qualitative detection lead ions was 2 ng/mL and the LOD for semi-quantitative detection could go down to 0.19 ng/mL using a scanning reader. The method suffered from no interference from other metal ions and could be used to detect trace lead ions in drinking water without sample enrichment. The recovery of the test samples ranged from 96% to 103%. As the detection method could be accomplished within 15 min, this method could be used as a potential tool for preliminary monitoring of lead contamination in drinking water.

Safety of water was for a long time and still is one of the most pressing needs for many countries and different communities. Despite the fact that there are potentially many methods to evaluate water safety, finding a simple, rapid, versatile, and inexpensive method for detection of toxins in everyday items is still a great challenge. In this study, we extend the concept of composites, impregnated porous fibrous materials, such as fabrics and papers, by single-walled carbon nanotubes (SWNTs), toward very simple but high-performance biosensors. They utilize the strong dependence of electrical conductivity through nanotubes percolation network on the width of nanotube-nanotube tunneling gap and can potentially satisfy all the requirements outlined above for the routine toxin monitoring. An antibody to the microcystin-LR (MC-LR), one of the common culprits in mass poisonings, was dispersed together with SWNTs. This dispersion was used to dip-coat the paper rendering it conductive. The change in conductivity of the paper was used to sense the MC-LR in the water rapidly and accurately. The method has the linear detection range up to 10 nmol/L and nonlinear detection up to 40 nmol/L. The limit of detection was found to be 0.6 nmol/L (0.6 ng/mL), which satisfies the strictest World Health Organization standard for MC-LR content in drinking water (1 ng/mL) and is comparable to the detection limit of the traditional ELISA method of MC-LR detection, while drastically reducing the time of analysis by more than an order of magnitude, which is one of the major hurdles in practical applications. Similar technology of sensor preparation can also be used for a variety of other rapid environmental sensors.

An ultrasensitive and rapid sequential injection analysis (SIA) based on real-time PCR (SIA-rt-PCR) assay was developed by using different nanoparticles for the detection of small molecule chemicals residues. Gold (Au) nanoparticle, conjugated with goat anti-rabbit IgG and duplex strand DNA (dsDNA), was used as a substitute for chemiluminescent probes in an SIA system. By indirect competitive immunoreactions in the SIA system, the gold nanoparticles were attached to antigens which were immobilized by superparamagnetic nanoparticles (SMNPs). The dsDNA on the gold nanoparticles was dehybridized and then the single-stranded DNA (ssDNA) was collected and quantified with rt-PCR, which showed a rather low linearity range from 2.5 attomol L(-1) (aM) to 250 femtomol L(-1) (fM) and the LOD was 1.4 aM. This method, which is rapid, automated and capable of high-throughput, was used to detect methyl-3-quinoxaline-2-carboxylic acid (MQCA) residues in real samples. The analytical results had a coefficient of variation of less than 15% and the recovery was 89-108%.

A one-step immunochromatographic assay (ICA) was developed for the detection of seven kinds of cephems in milk. Polyclonal antibodies (PcAb) with group-specific to cephems were raised in rabbits after immunization with cephalexin-keyhole limpet hemocyanin (KLH) conjugate. The specificity of anti-sera was determined by indirect competitive enzyme-linked immunosorbent assay (icELISA), and the 50% inhibitions (IC(50)) of cephalexin and cefadroxil were obtained at 1.5 ngmL(-1); IC(50) of cefatiofur, cefapirin, cefazolin, cefalothin and cefotaxine were 4, 3.7, 3.2, 4.5 and 5 ngmL(-1), respectively. The PcAb against cephems were conjugated to colloidal gold particles as the detection reagent for ICA strips to test for cephems. This method achieved semi-quantitative detection of cephems in <5 min, with high sensitivity to cephalexin and cefadroxil (both 0.5 ngmL(-1)). At the same time, cefatiofur, cefapirin, cefazolin, cefalothin and cefotaxine were detected at <100 ngmL(-1) in spiked processed-milk samples. This method was compared with an enzyme-linked immunosorbent assay by testing 40 milk samples, and the positive samples were validated by a high-performance liquid chromatographic method, with an agreement rate of 100% for both comparisons. In conclusion, the method was rapid and accurate for the multi-residue detection of cephems in milk.

An immunochromatographic assay was developed to detect chloramphenicol (CAP) residues in aquaculture tissues. The limit of detection (LOD) was 10 ng g(-1) for detecting CAP spiked in the aquaculture tissues. The results were confirmed by liquid chromatography tandem mass spectrometry (LC/MS/MS) and indicated that there was a good agreement between the two methods. The linear regression equation was y = 1.19x + 0.539 with R(2) = 0.978. The assay time for test was less than 5 min and the method is suitable for rapid testing on-site.

Human epidermal growth factor receptor 2 (HER2) is an important biomarker for detection and treatment of breast cancer. In this study, we developed monoclonal antibodies against the extracellular domain (ECD) of HER2 and established a rapid and accurate lateral flow immunoassay (LFIA) for use in community medical institutions. The gene sequence of human HER2-ECD was obtained from the National Center for Biotechnology Information (NCBI) to construct the expression plasmid. HER2-ECD protein expressed in HEK293F cells was used to immunize BALB/c mice. The monoclonal antibodies were produced in mouse ascites and isolated by hybridoma cell screening. Antibodies were analyzed for purity by SDS-PAGE (sodium dodecyl sulphate-polyacrylamide gel-electrophoresis) and affinity was assessed by enzyme-linked immunosorbent assay (ELISA) while subtypes were detected using the commercial kits. The HER2-ECD test strip was prepared based on the sandwich method and evaluated using a portable detection instrument. The affinity of the paired antibodies, 4D8 and 8D9, both reached 1 × 108 L/mol. Both antibodies specifically recognized the HER2-ECD protein in serum. The limit of detection (LOD) of the gold nanoparticle (AuNP)-based LFIA was 1.7 ng/mL with a detection range of 1.7–400 ng/mL, and the performance of the HER2-ECD strip correlated well with that of a Siemens chemiluminescent immunoassay (CLIA) kit. In conclusion, the paired antibodies were successfully prepared with high affinity and specificity. The AuNP-based LFIA of HER2-ECD provides a fast and accurate method to detect the concentration of HER2-ECD in serum samples for clinical use in community medical institutions, and could contribute to determining the progress of the disease or the effectiveness of treatment. [ABSTRACT FROM AUTHOR]

Abscisic acid (ABA) is a plant growth hormone that has a regulatory effect on plant physiology including accelerating fruit ripening, regulating abiotic stress tolerance and handling environmental risks. In this research, a highly sensitive monoclonal antibody (mAb) specific to abscisic acid was produced. We applied it to develop a method of lateral flow immunoassay (LFIA) on the basis of the indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) to analyze the content of abscisic acid in vegetable samples. The 50% inhibitory concentration (IC50) was 0.66 ng mL−1 with a cut-off value of the LFIA strip of 5 ng mL−1. The linear range was 0.28–2.57 ng mL−1 and the calculated LOD (cLOD) was 0.14 ng mL−1, respectively. The recoveries of the developed method ranged from 92.5% ± 3.2% to 102.2% ± 1.6% and 95.4% ± 3.6% to 108.2% ± 2.2% in tomato and cowpea samples with a coefficient of variation (CV) of 1.8–2.9% and 1.2–3.4%, respectively. The results showed that the developed method showed great prospects in the detection and monitoring of ABA in real food samples. [ABSTRACT FROM AUTHOR]

A monoclonal antibody against triamcinolone acetonide (TCA) and budesonide (BUD) was prepared using a hapten that was generated by introducing a carboxyl group into the structure of TCA. Based on the prepared monoclonal antibody, a gold nanoparticle-based lateral-flow immunoassay (GLFA) was developed with the ability to screen TCA and BUD in milk. The visible limits of detection of the GLFA for the analysis of TCA and BUD were 0.1 and 0.5 ng/mL with a cutoff value of 5 and 10 ng/mL, respectively, in milk. Average recoveries of TCA and BUD in milk were 92.0–102.2% and 96.0–98.8% with a good correlation between the results from the GLFA and LC-MS/MS analysis. These results demonstrated that the GLFA method for the rapid detection of TCA and BUD in milk samples is reliable and sensitive. [ABSTRACT FROM AUTHOR]

Butralin is a dinitrobenzene pesticide, has been widely used as a herbicide in many crops. Its high levels of residues threaten the ecological balance and human health. Therefore, establishment of a sensitive monoclonal antibody (mAb) for rapid detection of butralin residues is critical. In this study, special haptens were designed with good preservation of the characteristic structure of target compound. After mice immunization, a highly sensitive monoclonal antibody was produced. The half-maximum inhibitory concentration (IC 50) was 1.936 ng/mL. And we applied it to develop a method of lateral flow immunoassay (LFIA), with vLOD value of the LFIA strip to be 10 ng/mL. In watermelon and pear samples, the cLOD values of the LFIA strip were 0.432 ng/mL and 0.426 ng/mL, respectively. The recoveries of the developed method ranged from 94.4% ± 2.1%–112.1% ± 3.4% and 89% ± 5.4%–103% ± 4.1% in watermelons and pears samples, with a CV of 2.9%–3.4% and 2.2%–5.2%, respectively. The results demonstrated that the developed method showed great prospect in the detection and monitoring of butralin in real food samples. • New haptens of butralin was synthesized successfully. • Based on the anti- butralin monoclonal antibody, the strip assay was established. • The visual detection limit for flumioxazin was 5 ng/mL. • The strip assay can be applied in on-site monitoring of watermelon and pear samples. [ABSTRACT FROM AUTHOR]

Residues of flumetralin, a dinitroaniline herbicide, in foods pose a health risk to humans. In this study, we produced a sensitive monoclonal antibody (mAb) against flumetralin and developed a gold nanoparticle-based lateral flow immunoassay (LFIA) strip for screening flumetralin in orange. The subtype of mAb 3F5 was IgG1 and had a half-maximal inhibitory concentration of 9.43 ng mL−1. The cross-reactivity assay indicated that mAb had good specificity. The LFIA strip had a visual limit of detection of 200 ng g−1 in orange. We obtained results with the naked eye within 15 min. The calculated LOD of the strip in orange was 33.26 ng g−1, with a linear detection of 80.72–1672.10 ng g−1. The strip had recovery rates ranging from 98.4% to 110.1%. Therefore, our developed method is an effective and reliable tool for the rapid detection of flumetralin in orange. [ABSTRACT FROM AUTHOR]

In this study, a monoclonal antibody (mAb) 1G5 against novobiocin with high sensitivity and specificity was prepared from a newly-designed hapten. According to the results of an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA), the 50%-inhibitory concentration of the anti-novobiocin mAb was 6.9 ng/mL and the cross-reactivity was less than 0.1% to its analogues. Furthermore, a rapid colloidal gold immunochromatographic assay (ICA) was successfully developed for the determination of novobiocin in spiked samples. Two calibration curves were established respectively, for beef and chicken samples. The ICA results showed a visual colorimetric value of 50 ng/mL and a cut-off value of 300 ng/mL in beef samples. The ICA results of chicken samples were almost the same as that of beef. When quantitative detection was performed using a strip reader, the detection ranges for quantitative analysis in beef and chicken were 23.7–287.5 and 19.7–263.8 µg/kg respectively. Recoveries were between 82.7 and 95.3% for beef samples with the coefficient of variation (CV) ranging from 2.5 to 5.1%. Recoveries were in the range of 89.6–105.5% with the CV ranging from 2.9% to 6.3% for chicken samples. Importantly, these results from the ICA were highly consistent with the results obtained by LC-MS/MS. Therefore, this ICA could be used as an alternative means for the rapid determination of NOV in a large number of beef and chicken samples. [ABSTRACT FROM AUTHOR]

We have developed a sensitive and rapid gold nanoparticle-based immunochromatographic strip (GNP-ICS) for the detection of bifenthrin (BF) using an anti-BF monoclonal antibody (mAb). When used in indirect competitive enzyme-linked immunosorbent assay (icELISA), the specific anti-BF mAb (3D1) had a half-maximal inhibitory concentration (IC50) and limit of detection (LOD) of 59 and 15 ng mL−1 respectively. Additionally, its cross-reactivity (CR) with other pyrethroids was negative. The developed GNP-ICS assay based on the GNP-labelled mAb was specific and sensitive for determining BF, with a cut-off value of 1,000 ng mL−1, and a visual LOD (vLOD) value of 50 ng mL−1. Furthermore, the developed icELISA and GNP-ICS were applied with a simple pre-treatment to determine BF-spiked vegetable samples, and the recoveries were validated using gas chromatography-mass spectrometry (GC-MS). The results revealed that the developed GNP-ICS was reliable for the detection of BF in practical samples. [ABSTRACT FROM AUTHOR]

The excessive use of dapsone (DDS) in food animals could result in its accumulation in humans through the food chain, which in turn endangers human health. A sensitive monoclonal antibody (mAb) against DDS with a half inhibitory concentration (IC50) of 0.586 ng mL−1 was prepared in this study. Furthermore, a lateral flow immunoassay (LFIA) was established for the detection of DDS based on the anti-DDS mAb. Under optimized conditions, the developed LFIA had outstanding sensitivity with a visual limit of detection (vLOD) and a cut-off value of 1 ng mL−1 and 20 ng mL−1 for DDS in milk, respectively, which could be used for semi-quantitative detection of DDS. In milk sample analysis, a red test line on the LFIA strip signified <1 ng mL−1 DDS and a colorless test line signified >20 ng mL−1 DDS. In spiked samples and the recovery test, the results of the LFIA were in agreement with those of ic-ELISA, and the test using the LFIA strip could be completed within 15 minutes. Therefore, the established LFIA method in this study represents a reliable and compelling analysis for the rapid detection of DDS in milk. [ABSTRACT FROM AUTHOR]

In this study, a monoclonal antibody with selectivity for clopidol was produced based on a new hapten. The 50% inhibition concentration (IC50) for the developed ic-ELISA was 0.275 ng/mL. Cross-reactivity tests showed that the monoclonal antibody had high specificity for clopidol. Using this antibody, a lateral-flow colloidal gold immunoassay (LCGA) was created for the rapid screening of clopidol in raw chicken samples. With the naked eye, the cut-off value of the strip assay was 5 μg/kg for clopidol in chicken samples. Therefore, this LCGA provides a sensitive and rapid method for on-site detection of clopidol in chicken samples. [ABSTRACT FROM AUTHOR]

In this study, an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and a gold immunochromatographic assay were developed to detect the furaltadone metabolite, 3-amino-5-morpholinomethyl-2-oxazolidinone (AMOZ). The detection of AMOZ was based on the AMOZ derivative 3-([2-nitrophenyl] methyleneamino)-5-morpholinomethyl-2-oxazolidinone (2-NPAMOZ). The monoclonal anti-2-NPAMOZ antibody 4G11, was prepared and exhibited a 50%-inhibitory concentration (IC50) of 0.049 ng/mL. Its cross-reactivity with structurally related analogues was less than 3%. This immunochromatographic assay was assembled for the rapid screening of AMOZ in catfish samples. The strip assay had a cut-off value of 0.1 μg/kg and a limit of detection (LOD) of 0.009 μg/kg. Analysis of AMOZ in catfish indicated that the results from the strip assay were highly comparable to results obtained using ic-ELISA and LC-MS/MS. Therefore, the colloidal gold (CG) immunoassay is a sensitive screening method for the detection of AMOZ residues in catfish samples. [ABSTRACT FROM AUTHOR]

In this study, we produced a monoclonal antibody (mAb) 2F7 against cadmium (Cd) with IC50 of 0.20 ng/mL. The cross-reactivity of mAb 2F7 with other eight metals was < 1%. A fluorescent immunoassay strip was developed for the determination of Cd in rice. The cut-off value by visual inspection of the test strip was 50 μg/kg, and the quantitative detection range determined by the strip reader was 3.86–48.92 μg/kg. Both ic-ELISA and the fluorescent immunoassay strip can be used to detect Cd rice. Therefore, our developed fluorescent immunoassay strip may be an effective tool for detecting Cd in rice. [ABSTRACT FROM AUTHOR]

The label is a significant factor when analyzing the performance of lateral flow immunoassays (LFIAs) in practical applications. In this study, we first produced a broad-specificity monoclonal antibody (mAb) against five antibacterial synergists (ASGs) whose subclass was IgG2b and affinity constant was 1.30 × 1010 L mol−1. Then, time-resolved fluorescent microspheres (TRFMs) and colloidal gold nanoparticles (CGs) were used to label the mAbs, and the two different label-based LFIAs were developed and compared for their ability to quantitatively detect ASGs in chicken samples. Under optimal conditions, the limits of detection (LODs) of the TRFM-based LFIA were 0.001–0.01 μg kg−1 and those of the CG-based LFIA were 0.01–0.11 μg kg−1. The sensitivity of the TRFM-based LFIA was higher than that of the CG-based LFIA. In addition, owing to the visible test zone of the CG-based LFIA, qualitative results can be easily obtained. Analysis of real samples showed that results from the two LFIAs were consistent with that of an ic-ELISA. [ABSTRACT FROM AUTHOR]

A monoclonal antibody (mAb), 2C9, selective for four eugenol compounds, was developed based on the eugenol derivatives (Eug-1). The semi-inhibitory concentrations (IC50) of this antibody against eugenol, isoeugenol, methyl eugenol, and methyl isoeugenol were 0.043, 0.302, 0.016, and 0.082 μg/mL, respectively, and the detection limits (LOD) were 0.012, 0.070, 0.004 and 0.024 μg/mL. With the exception of isoeugenol, which had cross-reactivity of less than 15%, the cross-reactivity of the other compounds was good, ranging from 52.4% to 269%. In the ic-ELISA recovery test, recovery was between 80% and 94%, indicating that the method was suitable for analysis of eugenol compounds in water. The cut-off values of the immunochromatographic strips for the four compounds in water were 5, 100, 100, and 100 μg/mL, respectively, indicating that the ic-ELISA and immunochromatographic strips we developed can be used to rapidly detect eugenol compounds in water. [ABSTRACT FROM AUTHOR]

The problem of waste oil is a food safety issue that requires urgent resolution. In this study, a novel hapten was designed for the rapid detection of capsaicinoids, a marker of waste oil, and a monoclonal antibody (MAb) 5D7 was generated that is specific for three major capsaicinoids: capsaicin (CPC), dihydrocapsaicin (DCPC), and N-vanillylnonanamide (N-V). The half maximal inhibitory concentrations of MAb 5D7 for CPC, DCPC, and N-V were 1.12, 0.8, and 0.87 ng/mL, respectively. An immunochromatographic strip test based on MAb 5D7 was established for these three capsaicinoids, with visual inspection limits of <1.0 ng/mL, which satisfies the requirement for the rapid on-site inspection of waste oil. [ABSTRACT FROM AUTHOR]

A sensitive monoclonal antibody (mAb) (1H1) against fumonisin B1 (FB1) was produced in our laboratory. A rapid, simple, and an immunochromatographic strip has been developed for the ultrasensitive detection of FB1 in corn samples. Under the optimized condition, the cut-off limits of test strips for FB1 were found to be 50 ng/mL in 0.01 M PBS and 25 ng/mL in corn samples. Results could be obtained within 5 min. The results revealed that the developed method is a rapid, sensitive, and simple tool for the detection of FB1. [ABSTRACT FROM AUTHOR]

An anti-pefloxacin (PEF) monoclonal antibody (mAb), an indirect competitive enzyme-linked immunosorbent assay and lateral-flow test strip methods were developed to detect fluoroquinolone (FQ) residues in chicken muscle samples. Under optimised conditions, the anti-PEF mAb showed reasonable cross-reactivity with nine FQs with a limit of detection of 0.082 ng/mL assayed in 0.01 M phosphate buffered saline (PBS) solution. The intra- and inter-assay recoveries from spiked samples were within the range of 62.42-111.47% and 63.5-113.79%, respectively. The visual cut-off values of the lateral flow test strip in 0.01 M PBS and in food matrices were within the range of 2.5-50 ng/mL and 5-100 µg/kg, respectively. These results show that the anti-PEF mAb immunoassay and lateral flow test strip methods are suitable for simultaneous detection and routine monitoring of FQ residues in food. [ABSTRACT FROM AUTHOR]

A monoclonal antibody (mAb) directed against phenylethanolamine A (PEA) was successfully prepared with the immunization of mice and cell fusion, and used to develop a detection method for a colloidal gold immunoassay. The 50% inhibitory concentration of mAb PEA-2G10 was 0.213 ng/mL, the limit of detection was 0.033 ng/mL, and its detection range 0.033-0.679 ng/mL. The recovery rate for PEA in swine urine was 84.5-90.8%, with good stability and accuracy. “Dry” immunoassay test strips were successfully prepared based on antibody 2G10. When the strip was tested in swine urine, the cutoff value for PEA was 5 ng/mL, with highly sensitivity. The method developed here can be used to test swine urine on-site for the rapid detection of PEA. [ABSTRACT FROM AUTHOR]

A lateral-flow immunochromatographic assay (ICA) strip was developed for determination of tenuazonic acid (TeA) using both semi-quantitative and quantitative methods. The ICA strip was based on produced anti-TeA monoclonal antibody, and could be used for TeA analysis in cereal and fruit juice, with visual limits of detection of 1600 ng/g and 400 ng/mL, and cut-off values of 6400 ng/g and 3200 ng/mL, respectively. The calculated limits of detection values were 126.4 ng/g and 65.3 ng/mL for wheat and apple juice samples, respectively. The recovery rates ranged from 90% to 129%. In summary, the developed strip was effective for TeA detection and would be suitable for on-site detection and rapid screening of samples. [ABSTRACT FROM PUBLISHER]

An immunochromatographic strip was developed for the determination of alternariol(AOH) using both semi-quantitative and quantitative methods based on a sensitive monoclonal antibody we produced. With AOH-spiked samples, the visual limit of detection for cereal and juice were 160 ng/g and 25 ng/mL, and the cut-off values were 640 ng/g and 100 ng/mL, respectively. For quantitative analysis based on a strip scan reader, the calculated limit of detection was 15.5–19.4 ng/g for cereal and 2.8–3.5 ng/mL for fruit juice. The recovery rates ranged from 116% to 125%, and 113% to 123%, respectively. Therefore, this method was effective for AOH detection and suitable for on-site detection and rapid screening of samples. [ABSTRACT FROM PUBLISHER]

A lateral flow colloidal gold (CG) immunoassay strip has been developed for detection of dexamethasone (DEX) residues in milk samples. For this purpose, an anti-DEX monoclonal antibody (McAb), based on a DEX succinic anhydride derivative hapten, was prepared and characterized. The McAb showed a high specificity to DEX, the half inhibitory concentration of the antibody was 0.095 ng/mL, its limit of detection (LOD) was 0.017 ng/mL, and its linear range of detection was 0.034–0.265 ng/mL. The developed CG immunoassay had a visual cut-off value of 0.3 ng/mL in phosphate buffered saline (PBS) and 0.5 ng/mL in milk samples. Each test requires 10 min. Analysis of DEX in milk indicated that the results of strip assay had a strong agreement with indirect competitive enzyme-linked immunosorbent assay. Therefore, the CG immunoassay is a sensitive screening method for semi-quantitative and qualitative detection of DEX residues in milk samples. [ABSTRACT FROM PUBLISHER]

Foodborne pathogens cause diseases in humans. The traditional methods of detecting foodborne pathogens are time-consuming. The lateral flow immunoassay (LFIA) has become a widely used detection platform for onsite testing of various foodborne pathogens due to its time-efficiency, cost-effectiveness, portability, and ease of use. With the development of novel nanomaterials, the sensitivity of the LFIA has improved tremendously compared with traditional colorimetric LFIA sensors. This review first summarizes the principles and corresponding formats of the LFIA. Then, a detailed classification of nanomaterial label (e.g., metallic, carbon and selenium, fluorescent, and magnetic nanoparticles) synthesis, signal amplification strategy, and detection principles are discussed as related to food safety. Subsequently, the LFIA used in the detection of pathogenic bacteria, including Escherichia coli, Vibrio parahaemolyticus, Staphylococcus aureus, Listeria monocytogenes, and Salmonella, are classified and summarized. Multiple signal modes have been explored that improve the sensitivity of foodborne pathogen detection. Further improvement should focus on the design and preparation of high signal-to-noise ratio nanomaterials to achieve highly sensitive detection, and multitarget and multimode sensing. [ABSTRACT FROM AUTHOR]

Carbofuran is a highly toxic pesticide used in fruits and vegetables. In this study, we produced a specific and sensitive monoclonal antibody (mAb) which was prepared based on a hapten that was derivatized with benzofuranol against carbofuran. Following mice immunization and cell fusion, we obtained three monoclonal cell lines: 6D5, 3H2, and 3C6. The cell line 3H2 generated mAb with the highest affinity and sensitivity. The half maximal inhibitory concentration was 0.3 ng/mL, and the cross-reactivity was <1%. Based on this mAb, an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and immunochromatographic test strip (ICS) assay were developed to detect carbofuran residues in cucumbers and apples. The working range of ic-ELISA was 0.1–1 ng/mL, and the cutoff value of ICS was 1 ng/mL. The analytical recovery of carbofuran in cucumber and apple samples ranged from 81% to 97%. Both methods represent rapid screening tools for carbofuran detection in fruits and vegetables. [ABSTRACT FROM AUTHOR]

In this study, we developed an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and an immunochromatographic strip assay based on a monoclonal antibody (mAb) against methylmercury (MeHg) to detect the presence of MeHg in tap water. Under optimum conditions (pH 8.0, 0.8% NaCl, and 0.1% Tween 20), the 50% half maximal inhibitory concentration (IC50) and limit of detection (LOD) were 16.64 and 2.03 ng/mL, respectively. The anti-MeHg mAb was specific to mercury with no cross-reactivity with other metal ions. The cut-off value of the immunochromatographic strip assay was 500 ng/mL for semi-quantitative detection, and the LOD was 11.3 ng/mL for quantitative detection. The average recovery rates of the ic-ELISA and immunochromatographic strip assay were 98.13% and 107.87%, respectively, in tap water. Therefore, ic-ELISA and the immunochromatographic strip assay can be used to detect MeHg in tap water. [ABSTRACT FROM AUTHOR]

An amikacin-sensitive monoclonal antibody (MAb) assay and immunochromatographic test strip were developed and applied for the detection of amikacin residues in bovine milk and chicken eggs. The immunoassay was specific to amikacin and showed no cross-reactivity with other aminoglycosides. The half maximum inhibitory concentration (IC50) of the assay was 0.65 ng/mL and the results were obtained within 90 min. Recoveries from spiked food matrices were within the range of 73.55–84.61% for bovine milk and 73.70–105.75% for whole egg. The strip test results were obtained within 10 min and showed a visual detection limit of 5.0 ng/mL for both food matrices. These results show that the MAb immunoassay and strip test developed in this study are very specific to amikacin and sufficiently sensitive for detection and routine monitoring of amikacin residues in food. [ABSTRACT FROM AUTHOR]

The misuse and illegal use of fluoroquinolones (FQs) in animal-based food products have drawn considerable attention in several countries. As a result, there has been an increased demand for efficient detection methods of FQs in food products. In this study, we developed an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and immunochromatographic strip device based on a monoclonal antibody against lomefloxacin (LFLX), a second generation FQ. Ic-ELISA had an IC50value of 0.19 ng/mL with a limit of detection of 0.04 ng/mL in 0.01 M phosphate-buffered saline (PBS). The intra- and inter-assay recovery rates of LFLX in bovine milk samples were 98.02–107.40% and 100.65–107.82%. The immunochromatographic assay of LFLX in PBS and spiked bovine milk samples had visual cutoff values at 1 and 5.0 ng/mL, respectively, with significant cross-reactivity with norfloxacin and enoxacin. The developed ic-ELISA and strip method may assist in the detection of FQs in foods. [ABSTRACT FROM AUTHOR]

A monoclonal antibody (MAb) was produced against paromomycin and used in the development of an immunoassay and a lateral flow strip test for the detection of paromomycin residues in food matrices. The MAb had 25.1% cross-reactivity with neomycin, but was insensitive to other aminoglycosides. Tested under optimized conditions in 0.01 M phosphate-buffered saline, the half maximum inhibitory concentration (IC50) of the MAb was 0.61 ng/ml for paromomycin and 2.43 ng/ml for neomycin, with results obtained within 90 min. The mean recoveries from spiked food matrices were within the range of 64.56–105.85% for paromomycin and 54.08–100.55% for neomycin. The strip test results for different food matrices were obtained within 5 min and showed visual detection limits of 2.5–20 ng/ml (µg/kg) for paromomycin and 10–30 ng/ml for neomycin. Therefore, the developed immunoassay and strip test can be used in food analysis for routinely monitoring not only paromomycin but also neomycin residues. [ABSTRACT FROM AUTHOR]