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Zhou Y.,Jilin University | Song F.,Jilin University | Li Y.S.,Jilin University | Liu J.Q.,Production Quality Test Institute of Jilin Province | And 8 more authors.
Food Chemistry | Year: 2013

The concentration of casein (CN) is one of the most important parameters for measuring the quality of bovine milk. Traditional approach to CN concentration determination is Kjeldahl, which is an indirect method for determination of total nitrogen content. Here, we described a double-antibody based direct immunoassay for the detection of β-CN in bovine milk samples. Monoclonal antibody (McAb) was used as capture antibody and polyclonal antibody (PcAb) labelled with horseradish peroxidase (HRP) as detection antibody. With the direct immunoassay format, the linear range of the detection was 0.1-10.0 μmL-1. The detection limit was 0.04 μmL-1. In addition, the concentration of β-CN in real bovine milk samples has been detected by the developed immunoassay. There was a good correlation between the results obtained by the developed technique and Kjeldahl method from commercial samples. Compared to the traditional approach, the advantage of the assay is no need of time-consuming sample pretreatment. © 2013 Elsevier Ltd. All rights reserved. Source


Song F.,Jilin University | Zhou Y.,Jilin University | Li Y.S.,Jilin University | Meng X.M.,Jilin Business and Technology College | And 8 more authors.
Food Chemistry | Year: 2014

An immunomagnetic beads-based enzyme-linked immunosorbent assay (IMBs-ELISA) was developed for the detection of β-casein in bovine milk. Immunomagnetic beads (IMBs) were employed as the solid phase. The anti-β-casein monoclonal antibody (McAb) bound to IMBs was used as capture probe and an anti-β-casein polyclonal antibody (PcAb), labelled with horseradish peroxidase (HRP), was employed as detector probe. Three reaction and two washing steps were needed. Each reaction needed 10 min or less, which significantly shortened detection compared with classic sandwich ELISA. β-Casein in bovine milk was detected across a linear range (2-128 μg mL-1). Application results were in accordance with the Kjejdahl method, which suggests the IMBs-ELISA is rapid and reliable for the detection of β-casein in bovine milk. © 2014 Elsevier Ltd. All rights reserved. Source


Zhou Y.,Jilin University | Tian X.-L.,Ocean University of China | Li Y.-S.,Jilin University | Zhang Y.-Y.,Jilin University | And 6 more authors.
Analytica Chimica Acta | Year: 2012

Mercury ions (Hg(II)) are considered highly toxic and hazardous element even at low levels. The contamination of Hg(II) is a global problem. To develop selective and sensitive technique for the detection of Hg(II) has attracted considerable attention. In this study, a multi-component chemically reactive detection conjugate for determination of Hg(II) has been synthesized and a competitive format assay was proposed. In the technique, the chemically reactive capture conjugate was coated on the plate. The reactive detection conjugate was then captured by the capture conjugate. TMB solution was added and catalyzed by HRP molecules immobilized on AuNPs. Finally, the developed enzymatic signal was measured at 450. nm. The linear range of the assay was 0.35-350. ppb with a detection limit of 0.1. ppb. The average recoveries of Hg(II) from mineral water, tap water and lake water were 100.03%, 103.13% and 102.03%, respectively. All coefficients of variation (CVs) were less than 10%. The results are closely correlated with those from inductively coupled plasma mass spectrometry (ICP-MS), which indicated that the developed technique is a reliable method for and sensitive detection of Hg(II) in water samples. © 2012 Elsevier B.V. Source


Zhou Y.,Jilin University | Li Y.S.,Jilin University | Meng X.Y.,Jilin University | Zhang Y.Y.,Jilin University | And 9 more authors.
Chemosphere | Year: 2013

In this study we report the production of a monoclonal antibody (Mab) specific for Cr(III)-chelate and the development of a competitive immunoassay for detection of Cr(III) in water samples. In the assay, the complete antigen (Cr(III)-ITCBE-BSA) was used as coating antigen, and Cr(III)-ITCBE as competitor competes with coating antigen to bind with Mab. Using this approach, the spiked water samples with Cr(III) were detected. The linear range of the detection was 0.7-12.4ngmL?1. The limit of the detection (LOD) was 0.51ngmL?1. The spiked results were also confirmed by ICP-MS, which showed a good correlation (R2=0.997) between the two methods. The results indicated that the developed assay was reliable and suitable for the detection of Cr(III) in water samples. © 2013 Elsevier Ltd. Source


Zhou Y.,Jilin University | Tian X.-L.,Ocean University of China | Li Y.-S.,Jilin University | Pan F.-G.,Jilin University | And 10 more authors.
Biosensors and Bioelectronics | Year: 2011

A novel probe based on colloidal gold nanoparticles (AuNPs) modified with goat anti-mouse IgG and horseradish peroxidase (HRP) was synthesized and an enhanced enzyme-linked immunosorbent assay (ELISA) based on the probe was developed. In the assay, the synthesized probe is bound with a monoclonal antibody (McAb) which is competitively bound by coated BSA-ITCBE-Pb(II) on plate and Pb(II) in samples. The HRP, used here for signal amplification catalytically oxidize the substrate and generate optical signals that is related to the concentration of Pb(II) and can be measured spectrophotometrically. For the monodisperse AuNPs having high surface areas, it can be conjugated with more amount of HRP than that of IgG. Therefore, compared with traditional ELISA, the signal amplification of catalytically oxidized substrate was enhanced. The detection limit for this novel modified AuNPs probe-based assay was 9pgmL-1. The recoveries obtained by standard Pb(II) addition to real samples, including a commercial mineral water, tap water, and lake water were all from 94.9% to 102.9%. And the coefficient of variation (CV) value of all samples was less than 10%. The results indicated that the enhanced assay gave higher sensitivity and reliable reproducibility. It could provide a general detection format for low-molecular weight contaminants. © 2011 Elsevier B.V. Source

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