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Avian leukemia is an infectious tumorous disease of chickens caused by subgroup A of the avian leukemia virus (ALV-A), which mainly causes long-term viremia, slow growth, immune suppression, decreased production performance, multi-tissue tumors, and even death. The infection rate of this disease is very high in chicken herds in China, causing huge economic losses to the poultry industry every year. We successfully expressed the specific antigen protein of ALV (P27) through recombinant protein technology and screened a pair of highly sensitive monoclonal antibodies (mAbs) through mouse immunity, cell fusion, and antibody pairing. Based on this pair of antibodies, we established a dual antibody sandwich ELISA and gold nanoparticle immunochromatographic strip (AuNP-ICS) detection method. In addition, the parameters of the dual antibody sandwich ELISA and AuNP-ICS were optimized under different reaction conditions, which resulted in the minimum detection limits of 0.2 ng mL−1 and 1.53 ng ml−1, respectively. Commonly available ELISA and AuNP-ICS products on the market were compared, and we found that our established immune rapid chromatography had higher sensitivity. This established AuNP-ICS had no cross-reactivity with Influenza A (H1N1), Influenza A (H9N2), respiratory syncytial virus (RSV), varicella-zoster virus (VZV), Listeria monocytogenes listeriolysin (LLO), and Staphylococcal enterotoxin SED or SEC. Finally, the established AuNP-ICS was used to analyze 35 egg samples, and the results showed 5 positive samples and 30 negative samples. The AuNP-ICS rapid detection method established by our group had good specificity, high sensitivity, and convenience, and could be applied to the clinical sample detection of ALV-A. [ABSTRACT FROM AUTHOR]

Chloridazon (CLZ) is a selective herbicide used in the control of annual broadleaf weeds. The misuse or abuse of CLZ may result in the accumulation of CLZ in crops and water, which can pose a risk to human health. In this study, a hapten of CLZ with three carbon spacer arms was designed and a highly sensitive and specific antibody against CLZ was prepared with a half-maximal inhibitory concentration of 0.630 ng mL−1 and a linear range of 0.181–2.195 ng mL−1.Based on this antibody, we developed an immunochromatographic assay (ICA) strip for the detection of CLZ in oranges and celery. Under optimized conditions, the visual limit of detection was 2 ng mL−1 and 10 ng mL−1 in oranges and celery, respectively, and the cut-off value was 50 ng mL−1. In CLZ-spiked samples and the recovery test, the results of the ICA strip were consistent with those of indirect competitive enzyme-linked immunosorbent assay (ic-ELISA). Therefore, the ICA strip developed in our study represents an efficient and reliable method for the rapid screening of CLZ in oranges and celery. [ABSTRACT FROM AUTHOR]

In this study, we synthesized two haptens similar in structure to nitrofen (NIT), and screened out five monoclonal antibodies with the ability to recognize NIT and bifenox (BIF) by competitive ELISA, with the lowest IC50 values of 0.87 ng mL−1 and 0.86 ng mL−1, respectively. The antibody 5G7 was selected to be combined with colloidal gold to establish a lateral flow immunochromatographic assay strip. This method was shown to qualitatively and quantitatively detect the residues of NIT and BIF in fruit samples. The visual limits of detection for qualitative detection were 5 μg kg−1 and 10 μg kg−1 for NIT and BIF, respectively. The calculated limits of detection for quantitative detection were 0.75 μg kg−1, 1.77 μg kg−1 and 2.55 μg kg−1 respectively, for nitrofen in orange, apple and grapes, and 3.54 μg kg−1, 4.96 μg kg−1 and 5.26 μg kg−1, respectively, for bifenox. Thus the strip assay could be used for rapid analysis of fruit samples. [ABSTRACT FROM AUTHOR]

Cannabidiol (CBD), the most predominant cannabinoid, may cause addiction and liver damage. In this study, we synthesized a CBD hapten containing the carboxyl group of the spacer arm by derivatizing CBD. A highly specific and sensitive monoclonal antibody (mAb) was prepared with a half-maximal inhibitory concentration of 2.03 ng mL−1 and a limit of detection of 0.32 ng mL−1. MAb was highly specific for CBD. We developed an immunochromatographic assay (ICA) for the detection of CBD in functional beverages with a visible limit of detection of 100 ng mL−1 and a cut-off of 1000 ng mL−1. Compared with HPLC, ICA is more efficient and accurate and can be used for the rapid on-site detection of CBD in samples. [ABSTRACT FROM AUTHOR]

Chlordimeform (CDM) is a broad-spectrum and highly effective insecticide and acaricide used to control pests in agriculture. We produced two monoclonal antibodies (mAbs) against CDM and developed an immunochromatographic assay to screen CDM in cucumbers and tomatoes. MAb 4A3 had high sensitivity with a 50% inhibitory concentration of 0.287 ng mL−1. The assay had a cut-off value of 25 μg kg−1 and a visual limit of detection (vLOD) of 1 μg kg−1 in cucumbers and a cut off value of 50 μg kg−1 and a vLOD of 2.5 μg kg−1 in tomatoes. The calculated limit of detection (cLOD) in cucumbers and tomatoes was 0.115 μg kg−1 and 0.215 μg kg−1, respectively. The recovery rates were 97.9% to 106.9% for cucumbers and 97.8% to 107.4% for tomatoes, consistent with the results obtained from indirect competitive ELISA. Our findings showed that the immunochromatographic assay is an efficient and accurate method for CDM detection in cucumbers and tomatoes. [ABSTRACT FROM AUTHOR]

The synthetic antibiotics fluoroquinolones are popular due to their good antibacterial performance and low price, but the risk to human health caused by their residues has attracted great attention. In this study, an ultra-sensitive mAb, 4D7, was prepared with an IC50 of 0.027 ng mL−1 to norfloxacin (NOR) and cross-reactivity of 19.7–47.7% to lomefloxacin (LOM), pefloxacin (PEF), ofloxacin (OFL), enrofloxacin (ENR), ciprofloxacin (CIP), and danofloxacin (DAN). Based on mAb 4D7 and Eu-fluorescent microspheres, a rapid and sensitive immunochromatographic strip was developed for the detection of fluoroquinolone residues in fish and milk. The detection ranges (IC20–IC80) of the strip for the detection of NOR, PEF, LOM, OFL, ENR, CIP and DAN were 0.19–1.1 μg kg−1, 0.39–2.1 μg kg−1, 0.5–2.6 μg kg−1, 0.43–3.3 μg kg−1, 0.61–3.5 μg kg−1, 0.69–5.5 μg kg−1, 0.52–3.4 μg kg−1 in fish, and 0.027–0.19 μg kg−1, 0.049–0.34 μg kg−1, 0.069–0.39 μg kg−1, 0.06–0.41 μg kg−1, 0.089–0.65 μg kg−1, 0.12–0.81 μg kg−1, 0.091–0.52 μg kg−1 in milk, respectively. The recovery rates in spiked sample tests were 88.6–113.6% with a coefficient of variation less than 8.4%. Thus the newly-developed strip was sensitive and reliable for rapid on-site detection of fluoroquinolone residues in fish and milk. [ABSTRACT FROM AUTHOR]

Anthranilic diamide insecticides, including chlorantraniliprole (CHL), cyantraniliprole (CYA), cyclaniliprole (CYC), and tetrachlorantraniliprole (TEA), are widely used in agricultural production, resulting in potential risk to human health. In this study, we designed novel haptens for the preparation of a broad-specific monoclonal antibody (mAb) against CHL, CYA, CYC, and TEA simultaneously. The mAb 4F5 we produced belonged to the IgG1 subtype and had 50% inhibition concentration (IC50) values ranging from 0.06 to 0.19 ng mL−1 for all four anthranilic diamides. We further developed a mAb-based lateral flow immunochromatographic strip for the detection of anthranilic diamides in vegetables and fruits. Under optimal conditions, the strip provided cut-off values of 2.5, 5, 10, and 10 ng g−1 for CHL, CYA, CYC, and TEA, respectively, within 15 min. Collectively, these data show that the proposed strip assay is a convenient and practical method for the rapid screening of anthranilic diamides in food samples. [ABSTRACT FROM AUTHOR]

Homocysteine (Hcy) is an amino acid found in the human body and has the potential to predict cardiovascular risk where timely detection and treatment are very important. In this study, we established a method to combine enzymatic hydrolysis with a colloidal gold lateral flow immunoassay (LFIA) for the detection of total Hcy (tHcy) based on the monoclonal antibody (mAb) 3B3 against S-adenosyl- L -homocysteine (SAH). The 50% inhibitory concentration (IC50) for this mAb against SAH was 2.94 nM with a linear range of 0.73–11.75 nM. The developed LFIA could detect SAH with a vLOD and cLOD of 10 nM and 2.07 nM, respectively. For tHcy detection in serum samples, the LFIA strip was able to detect tHcy after enzymatic hydrolysis, and the results correlated well with that of an enzymatic cycling test kit. [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 highly specific and sensitive monoclonal antibody against dicofol (DIC) was prepared and used to create a colloidal gold immunochromatographic strip (ICS) for the quantitative analysis of DIC in liquorice and Angelica sinensis samples. We found that for both the liquorice and Angelica sinensis samples, the cut-off value for the ICS was 500 ng g−1, respectively, and using a colloidal gold test strip reader, the half-maximal inhibitory concentrations (IC50) were found to be 35 ng g−1 and 88 ng g−1, the limits of detection were 2 ng g−1 and 3 ng g−1, and the linear detection scopes (IC20–IC80) were from 6 to 201 ng g−1 and from 10 to 819 ng g−1, respectively. In the recovery test, we found that recoveries were within the range of 90.6% to 97.2% and the coefficients of variation were less than 8.6% in the intra-assay and inter-assay for the liquorice samples and the recoveries ranged from 90.8% to 97.3% and the coefficients of variation were less than 9.1% in the intra-assay and inter-assay for the Angelica sinensis samples. The established ICS assay could be used for the rapid quantitative screening of chemicals in Chinese traditional medicinal materials. [ABSTRACT FROM AUTHOR]

tert-Butylhydroquinone (TBHQ) residues in foods pose a threat to human health. Therefore, it is necessary to develop a rapid method for TBHQ detection. In this study, a sensitive monoclonal antibody 5C3 (IgG2a subclass) against TBHQ was produced. It possessed a half maximal inhibitory concentration of 7.43 ng mL−1. A gold nanoparticle-based immunochromatographic assay (ICA) was established for the rapid and sensitive screening of TBHQ in soybean oil. Qualitative analysis results were obtained within 10 min and observed with the naked eye. The visual limit of detection (LOD) was 50 ng g−1 and the cut-off value was 1000 ng g−1. A hand-held strip reader was used for quantitative analysis, in which the calculated LOD was defined as 18.68 ng g−1. The average recoveries of TBHQ ranged from 89.55% ± 2.70% to 100.66% ± 3.02% for soybean oil, with a coefficient of variation of 2.89%–7.05%. Therefore, our developed ICA is a useful tool for the rapid and on-site detection of TBHQ in real food samples. [ABSTRACT FROM AUTHOR]

Sirolimus is a potent macrolide immunosuppressant, with a long half-life, a narrow therapeutic window, and large individual variations in pharmacokinetics. In this study, an indirect enzyme-linked immunosorbent assay (ic-ELISA) and a colloidal gold-based immunochromatographic strip were developed to establish a rapid and efficient clinical screening of sirolimus. The hapten for sirolimus was synthesized by the oximation reaction and then coupled to keyhole limpet hemocyanin (KLH) and bovine serum albumin (BSA) to prepare the immunogen and coating antigen. Based on highly specific monoclonal antibodies (mAbs), the 50% inhibitory concentration (IC50) of the optimized ic-ELISA was 1.54 ng mL−1 and the limit of detection (LOD) was 0.19 ng mL−1 in whole blood samples. Good specificity was revealed by its low cross-reactivity (CR) with several analogs of sirolimus. The visual limit of detection (vLOD) and cut-off values of the strip were 20 and 100 ng mL−1 in whole blood samples, as assessed by the naked eye. Therefore, both methods could be used as potentially rapid monitoring approaches for the detection of sirolimus in human whole blood. [ABSTRACT FROM AUTHOR]

Most patients with idiopathic membranous nephropathy (IMN) have autoimmune antibodies specifically against the M-type phospholipase A2 receptor (PLA2R). PLA2R acts as a significant biomarker contributing to the clinical diagnosis of IMN. Herein, we performed the secretory expression of the exocellular domain and immune-dominant regions of PLA2R by using mammalian cells. Using ELISA, we confirmed that the purified His-tagged PLA2R variant of CysRC1C2C7, which contained CysRC1C2 (aa 21–510) and CTLD7 (aa 1097–1246), possesses the strongest binding affinity toward serum anti-PLA2R in IMN patients. The signal peptide of interleukin-2 for secretion was selected, and parameters for transient expression were optimized to achieve the highest titer of CysRC1C2C7. Stepwise purification of CysRC1C2C7 using anion-exchange chromatography and gel filtration apparently increased its capability of anti-PLA2R recognition or interaction in ELISA. Under optimal conditions of expression and purification, the yield of CysRC1C2C7 in monomer form was ∼14.1 mg L−1, with a recovery rate of ∼77%. This recombinant PLA2R variant had decent potential for serological analysis of anti-PLA2R in IMN patients. [ABSTRACT FROM AUTHOR]

Hyoscyamine (HSM), which acts as an antagonist of the acetylcholine muscarinic receptor and can induce a variety of distinct toxic syndromes in mammals (anti-cholinergic poisoning), is hazardous to human health. Therefore, it is urgent to develop a rapid, sensitive, and cost-effective method to determine HSM. A fluorescent microsphere based immunochromatographic assay was developed for this analyte and gold nanoparticles (AuNPs) were used as a comparison. A monoclonal antibody against HSM was prepared with a 50% inhibition concentration (IC50) of 1.17 ng mL−1, with no cross-reactivity with five drugs. Under optimized conditions, the cut off limits using the fluorescence-labeled monoclonal antibody strips were 10 ng mL−1 in 0.01 M PBS and 20 ng mL−1 in pork, pig urine, and honey samples, and the assay could be completed within 10 min. In comparison with a AuNP immunochromatographic assay, the developed method offered a higher coupling rate and lower amounts of antibodies. This approach could be used for simple, sensitive and rapid screening, and is suitable for on-site screening applications. [ABSTRACT FROM AUTHOR]

In this study, a highly specific and sensitive monoclonal antibody (mAb) against quinclorac (Qui) was prepared. Based on the selected mAb, 2G3, an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and an immunochromatographic strip assay were established for the detection of Qui in actual samples. The 50%-inhibitory concentration of mAb 2G3 against Qui was 48.763 ng mL−1. No cross-reaction with other quinolines indicated that mAb 2G3 had high specificity. The recovery of the established ic-ELISA method was in the range of 85.6% to 98.9%. The cut-off value of Qui in cucumber and tomato by immunochromatographic strip was 200 ng g−1. The analysis results of ic-ELISA and immunochromatographic strip assay were consistent with the results of LC-MS/MS, which further proved that the established ic-ELISA and immunochromatographic strip assay could provide valuable tools for the rapid detection of Qui residues in cucumber and tomato samples. [ABSTRACT FROM AUTHOR]

As the use of non-steroidal anti-inflammatory drugs (NSAIDS) increases, their side effects have also attracted attention. Ibuprofen is one of the most widely-used NSAIDs. In this study, we screened the highly-sensitive and specific antibody 6E10, with an IC50 of 1.92 ng mL−1, and a linear range of 0.53–6.97 ng mL−1. In this study, we developed a rapid lateral flow immunochromatographic assay (ICA) strip method to detect ibuprofen in water or herbal tea. The cut-off limit of the strip is 10 ng mL−1 in water, and concentrations as low as 1 ng mL−1 can be detected in herbal tea samples, with the results obtained by the naked eye within 6 min. All the data were confirmed by high performance liquid chromatography-quadrupole time of flight-mass spectrometry (HPLC-QTOF-MS). This lateral-flow ICA strip is thus a rapid tool for on-site detection and screening of ibuprofen in water and herbal tea. [ABSTRACT FROM AUTHOR]

We have developed a sensitive and rapid gold nanoparticle-based immunochromatographic strip (GNP-ICS) for the detection of phenacetin (PNCT) and paracetamol (PAP) using an anti-PNCT monoclonal antibody (mAb). The sensitive anti-PNCT mAb (2D6) had a half maximal inhibitory concentration (IC50) and limit of detection (LOD) of 3.51 and 0.21 ng mL−1, respectively. Additionally, its cross-reactivity with PAP was approximately 10.1%. The developed GNP-ICS assay based on GNP-labeled mAb was sensitive for the detection of PNCT with vLOD and cut-off values of 2.5 and 50 ng mL−1 respectively and a vLOD value of 25 ng mL−1 for PAP. Furthermore, the developed icELISA and GNP-ICS assays were applied to determine PNCT-spiked beverage samples without pretreatment, in addition to a kind of PAP-containing drug. The recoveries were validated using high performance liquid chromatography (HPLC). The results revealed that the developed GNP-ICS assay was reliable for the detection of PNCT in practical samples. [ABSTRACT FROM AUTHOR]

We prepared monoclonal antibodies (mAbs) against diminazene and used them in the development of a gold nanoparticle-based lateral-flow test (GNT) strip and indirect competitive enzyme-linked immunosorbent assay for the detection of diminazene in beef and beef liver samples. MAbs, which belong to the IgG2a subclass, had a half maximal inhibitory concentration of 0.04 ng mL−1. Based on cross-reactivity, mAb against diminazene was highly specific. The visual limit of detection (vLOD) of the GNT strip was 0.1 μg kg−1, and the cut-off value was 1 μg kg−1 in beef samples. The vLOD of the GNT assay was 0.1 μg kg−1, and the cut-off value was 2 μg kg−1 in beef liver samples. The average recoveries of diminazene ranged from 97.5% to 103.7% when using ic-ELISA. The accuracy of the developed GNT strip was confirmed by comparing the results with the ic-ELISA results. We developed a reliable GNT strip assay for the rapid detection of diminazene in beef and beef liver samples. [ABSTRACT FROM AUTHOR]

This report describes the development of a sensitive and broadly specific indirect competitive enzyme-linked immunosorbent assay (icELISA) and a gold nanoparticle-based immunochromatographic strip (GNP-ICS) assay for the detection of benzo[a]pyrene (B[a]P), using an anti-B[a]P monoclonal antibody (mAb). A broad-specific anti-B[a]P mAb (4E8) was raised from two types of haptens, with half maximal inhibitory concentrations and limits of detection (LOD) values of 2.51 and 0.54 ng mL−1, respectively. In addition, the cross-reactivity was up to 390% with structurally related compounds. The GNP-ICS assay based on a GNP-labeled mAb showed broad specificity in the detection of B[a]P and its analogues, with cut-off and visual LOD values of 100 and 10 ng mL−1, respectively. Furthermore, the recoveries from the developed icELISA and GNP-ICS assay in edible oil samples spiked with B[a]P were validated by high-performance liquid chromatography–fluorescence detection. The results revealed that the icELISA could reliably detect B[a]P in edible oils. [ABSTRACT FROM AUTHOR]

Chlorpheniramine (CPM) is an illegal additive found in herbal teas and health foods, and its excessive intake can cause health problems. In this study, a CPM monoclonal antibody (mAb) was developed based on a new type of hapten. The mAb was found to belong to the IgG2b subclass and showed high sensitivity and specificity when used in ELISA, with a half-maximal inhibitory concentration (IC50) of 0.98 ng mL−1 and cross-reactivity (CR) values below 1.8% when compared to antiallergic drugs. Based on the mAb produced, a fluorescent microsphere-based immunochromatographic strip assay (FM-ICS) and a gold nanoparticle-based immunochromatographic strip assay (GNP-ICS) were developed for the rapid and sensitive detection of CPM in herbal tea samples. Under optimal conditions, the cut-off values for the FM-ICS and GNP-ICS were 10 ng mL−1 and 100 ng mL−1, respectively, in herbal tea samples. The FM-ICS exhibited a higher sensitivity than GNP-ICS, but both could produce results within 15 min. In addition, a variety of high-throughput rapid immunoassay formats could be implemented based on this mAb for use as a convenient and reliable tool for the determination of CPM exposure in foods and the environment. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 (IC50) 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. [ABSTRACT FROM AUTHOR]

The polypeptide antibiotics colistin (COL) and bacitracin (Baci) are extensively used as veterinary drugs and feedstock additives in the livestock industry, which inevitably causes residues in animal-origin food, which can accelerate human tolerance to antibiotics. In this study, a portable lateral flow immunoassay (LFIA) for the simultaneous determination of COL and Baci residues in milk was developed. The replacement of gold nanoparticles used in the traditional LFIA with fluorescent microspheres (FMs) to label monoclonal antibodies (mAbs) allowed qualitative and quantitative analyses within a few minutes. Based on the principle of competitive binding to FM-labelled mAbs between analytes in samples and fixed antigens on the membrane, the assay provided qualitative cut-off values of 100 and 50 ng mL−1 for Baci and COL in milk samples. Furthermore, a strip reader-based semi-quantitative detection system could detect lower limits of 7.85 and 1.89 ng mL−1 for Baci and COL, respectively. In conclusion, the proposed multiplex LFIA immunosensor provides an auxiliary analytical tool for the rapid and simultaneous screening of COL and Baci in large cohorts of samples. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Tetrodotoxin (TTX) is a potent marine neurotoxin. Its frequent detection and widespread distribution pose a substantial health risk to consumers. The work presented herein describes the development of a lateral flow immunosensor based on a gold nanoparticle-labeled monoclonal antibody probe, which allows the affinity reaction of antigen–antibody and amplifies the reaction signal. The immunosensor assay was found to provide a visible limit of detection (vLOD) of 10 μg kg−1 in crucian and clam matrices without time-consuming pretreatment. Spiked samples were analyzed using the immunosensor and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The immunosensor gave average intra-assay recoveries of 84.0–103.9%, inter-assay recoveries of 76.1–105% for the crucian matrix and intra-assay recoveries of 78.5–93.0%, inter-assay recoveries of 74.8–85.7% for the clam matrix. The results obtained using the immunosensor and LC-MS/MS were in good agreement. The immunosensor test could be completed within 10 min, offering a convenient option or complementarity to the traditional methods of TTX detection. [ABSTRACT FROM AUTHOR]

This report describes the development of a sensitive and broadly specific indirect competitive enzyme-linked immunosorbent assay (icELISA) and a gold nanoparticle-based immunochromatographic strip (GNP-ICS) assay for the detection of benzo[a]pyrene (B[a]P), using an anti-B[a]P monoclonal antibody (mAb). A broad-specific anti-B[a]P mAb (4E8) was raised from two types of haptens, with half maximal inhibitory concentrations and limits of detection (LOD) values of 2.51 and 0.54 ng mL-1, respectively. In addition, the cross-reactivity was up to 390% with structurally related compounds. The GNP-ICS assay based on a GNP-labeled mAb showed broad specificity in the detection of B[a]P and its analogues, with cut-off and visual LOD values of 100 and 10 ng mL-1, respectively. Furthermore, the recoveries from the developed icELISA and GNP-ICS assay in edible oil samples spiked with B[a]P were validated by high-performance liquid chromatography-fluorescence detection. The results revealed that the icELISA could reliably detect B[a]P in edible oils.

The polypeptide antibiotics colistin (COL) and bacitracin (Baci) are extensively used as veterinary drugs and feedstock additives in the livestock industry, which inevitably causes residues in animal-origin food, which can accelerate human tolerance to antibiotics. In this study, a portable lateral flow immunoassay (LFIA) for the simultaneous determination of COL and Baci residues in milk was developed. The replacement of gold nanoparticles used in the traditional LFIA with fluorescent microspheres (FMs) to label monoclonal antibodies (mAbs) allowed qualitative and quantitative analyses within a few minutes. Based on the principle of competitive binding to FM-labelled mAbs between analytes in samples and fixed antigens on the membrane, the assay provided qualitative cut-off values of 100 and 50 ng mL-1 for Baci and COL in milk samples. Furthermore, a strip reader-based semi-quantitative detection system could detect lower limits of 7.85 and 1.89 ng mL-1 for Baci and COL, respectively. In conclusion, the proposed multiplex LFIA immunosensor provides an auxiliary analytical tool for the rapid and simultaneous screening of COL and Baci in large cohorts of samples.