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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, we developed a monoclonal antibody against picoxystrobin (PIC). After cell fusion, four cell lines (3C2, 4D1, 4G4 and 5D4) capable of producing monoclonal antibodies against oxystrobin were obtained. The monoclonal antibody produced by the cell line 3C2 was the most sensitive to PIC, and its IC50 value was 0.1 ng/ml. The monoclonal antibody was then used to prepare immunochromatographic strips, and its cut-off values in both phosphate-buffered saline solution and cucumber samples were 50 and 100 ng/ml, respectively. It was concluded that the ICS can sensitively and rapidly detect PIC in cucumber 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]

Lead (Pb) is a toxic metal that can accumulate in the body and negatively impact human health. In this study, we prepared a highly sensitive and specific monoclonal antibody, 2C3, that can recognize Pb(II) with an IC50 and linear range of 0.5 ng/mL and 0.08–1.86 ng/mL, respectively. Additionally, based on this antibody we developed a fluorescent test strip, which can be used for both qualitative and quantitative detection of Pb(II) in brown rice with a detection range of 4.67–47.8 ng/mL. Therefore, the method we developed has high sensitivity suitable for the detection of Pb(II) in brown rice. [ABSTRACT FROM AUTHOR]

Three heterogenous haptens (3,4,5-Trimethoxybenzoic acid [H1], 3,4,5-Trimethoxyphenylacetic acid [H2], 3-(3,4,5-Trimethoxyphenyl) propanoic acid [H3]) were used to synthesize immunogens, with the aim of screening a more sensitive monoclonal antibody (mAb) for trimethoprim (TMP). H2 proved to be the best heterogenous hapten. The mAb was specific with no cross-reactivity with other structurally related chemicals. The 50% maximal inhibitory concentration of the mAb against TMP was 1.98 µg L−1, which is more sensitive compared with the mAb reported in our previous work. A mAb-based gold immunochromatographic assay (GICA) was established to analyze TMP residues in milk and honey samples. The concentration of coating antigen in test line and concentration of mAb conjugated with gold nanoparticles was 0.3 µg mL−1and 0.25 µg mL−1, respectively. Under optimized conditions, the visual limit of detection concentration of TMP spiked in milk and honey samples was 10 µg L−1and 15 µg kg−1, respectively. The proposed GICA provides rapid and simple determination of TMP residues in milk and honey samples. [ABSTRACT FROM PUBLISHER]

A lateral flow assay for rapid, simple and efficient determination of L. monocytogenes is presented. A monoclonal antibody (mAb) 1C1 against the peptide from P60 protein of L. monocytogenes was prepared and labeled with gold nanoparticles (AuNPs). The mAb 1C1 was paired with the mAb 10E7 against the P60 protein of all the Listeria spp. and used as a capture bioligand in a lateral flow assay. The AuNP-based strip test can detect the supernatant of eight common L. monocytogenes serotypes including 1/2a, 1/2b, and 4b with an equivalent detection limit of 3.7 × 10 CFU⋅mL but does not detect four other Listeria spp. ( L. ivanovii, L. innocua, L. welshimeri, and L. grayi). There was no cross-reactivity with six other Gram-negative and Gram-positive bacteria. The method was applied to the quantification of L. monocytogenes species in spiked milk samples within 13 h. [ABSTRACT FROM AUTHOR]

The genus ofListeriaconsists of heterologous species and its presence in the food chain is an indicator of poor hygiene. However, a portable and simple paper sensor for detection of listeria spp. with high accuracy was still unknown. In this study, we prepared a pair of monoclonal antibodies (mAbs) that specifically recognize the P60 protein on the cell surface ofListeriaspp. The selected pair was found to be sensitive to both the P60 protein and cell body of the genusListeria. On this basis, a rapid paper sensor was established for sensitiveListeriaspp. detection. The developed paper sensor broadly cross-reacted with the 12 tested strains ofListeriaand the sensitivity in PBS buffer was 103–104colony-forming units (CFU) judged by the gray values of the test line. No cross-reaction with any other gram-positive or gram-negative strains tested was observed. A study using milk samples showed that this paper sensor could detect samples contaminated with low levels of the testedListeriaspp. (1–9 CFU/mL) after 8 h of enrichment and further concentrate for approximately 10 times by centrifugation. The results were in accordance with those obtained using the polymerase chain reaction method. [ABSTRACT FROM AUTHOR]

Kunitz trypsin inhibitor (KTI) is a predominant anti-nutritional factor in soybean. The objective of this study was to develop a sandwich enzyme-linked immunosorbent assay and immunochromato graphic strip (ICS) method for the semi-quantification of KTI in soybean. The limit of detection was 0.1481 ng/ml, and the linear dynamic range was 0.2–20 ng/ml. KTI recovery was 98.40–110.66% from KTI-spiked milk samples, with coefficients of variation of 4.41–10.62%. Based on ICS results, KTI had cutoff values of 5 ng/ml and 2.5 ng/ml in 0.05% Tween-added phosphate-buffered saline and milk, respectively. ICS has potential applications for the fast detection of KTI. [ABSTRACT FROM AUTHOR]

Staphylococcal enterotoxins (SEs) in food samples can cause severe gastroenteritis even at low doses. Detection of SEs with a single assay would not only improve reliability and portability, but would also save time. In this paper, for the first time, a multiplexed gold-nanoparticle-based immunochromatographic (ICT) strip that allows the simultaneous detection of the five main SEs has been reported: SEA, SEB, SEC, SED, and SEE. Based on the sandwich immunoassay of each SE, a multiplexed ICT strip with five test lines is developed. Sensitive and specific paired monoclonal antibodies facilitate the detection, allowing for high sensitivity and good specificity. The portable biosensor platform can simultaneously detect SEA, SEB, SEC, SED, and SEE at concentrations as low as 2.5, 2.5, 2.5, 1, and 5 ng mL−1, respectively. The entire test can be performed within 15 min and requires no sophisticated instruments except a portable strip reader. To evaluate the multiplexed strip, naturally SEA and SEC contaminated milk samples and pure milk samples spiked with the five SEs are analyzed. [ABSTRACT FROM AUTHOR]

Hen egg is one of the most frequent causes of food allergy in infants and adults. Ovalbumin (OVA) has been identified as a major egg allergen. In order to detect OVA in foods, a highly sensitive sandwich enzyme-linked immunosorbent assay (ELISA) based on two monoclonal antibodies (mAbs) was established. The 2 mAbs were selected out of 17 murine hybridomas secreting OVA-specific antibody. Using mAb17 as the capture antibody and mAb15 as the detection antibody, the detection limit of the ELISA method was 0.51 ng/mL, and the linear dynamic range was between 1.95 and 500 ng/mL. The recovery ranged from 85.6 to 115.2%, whereas the intra- and inter-assay coefficients of variation were less than 8.6 and 13.9%, respectively. Sample analysis verified that the produced anti-OVA mAb and the developed ELISA may provide a valuable tool for the sensitive determination of OVA in processed foods and for future studies on the mechanism of how OVA functions in anaphylaxis. [ABSTRACT FROM PUBLISHER]