Submitted to: Biosensors and Bioelectronics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/6/2010
Publication Date: 1/15/2011
Publication URL: http://handle.nal.usda.gov/10113/57272
Citation: Zhu, K., Li, J., Wang, Z., Jiang, H., Beier, R.C., Xu, F., Shen, J., Ding, S. 2011. Simultaneous detection of multiple chemical residues in milk using broad-specifity antibodies in a hybrid immunosorbent assay. Biosensors and Bioelectronics. 26:2716-2719. Interpretive Summary: The sulfonamide and quinolone antibiotics are widely used in agriculture, and melamine has been used to adulterate milk and milk products. We have developed a novel immunoassay that will quantify a group of sulfonamide and a group of quinolone antibiotics using broad-specificity antibodies that recognize six sulfonamides and eleven quinolone antibiotics, and we also determined the content of melamine using a specific antibody. Antibodies are substances that are produced by the immune system in response to foreign substances which enter the body. Once the antibodies to a foreign substance are isolated, they can be used in a method to detect the presence of these foreign substances. Broad-specificity antibodies can recognize a number of structurally similar chemicals. This immunoassay uses fluorescence for detecting the test results for the antibiotics, but the test for melamine uses a common enzyme-linked immunosorbent assay, or ELISA. All tests can be performed simultaneously on the same sample in the same sample well.
Technical Abstract: The wide array of applications using quantum dots (QDs) for detection of multiple analytes reflects the versatility of the technology. In this study, a novel immunoassay using 2 types of sensors (QDs and an enzyme) were simultaneously used for detecting multiple structurally different low-molecular weight molecules in milk. The method integrates the fluorescence-linked immunosorbent assay (FLISA), using QD®605 and QD®655 as probes, and an enzyme-linked immunosorbent assay (ELISA), using horseradish peroxidase (HRP)-labeled secondary antibodies. The FLISA was produced by coupling anti-sulfonamide and anti-quinolone broad-specificity monoclonal antibodies (MAbs) to QD®605 and QD®655 for simultaneously detecting 6 sulfonamides and 11 quinolones. Combined with the FLISA, an ELISA was utilized for detecting melamine from the same milk samples. The cross-reactivity of the MAbs was retained while binding the QDs by using avidins and secondary antibodies as bridges. The results demonstrated that the detection limits of the integrated methods were better than required and simplified the sample pretreatment process. The developed immunoassay is suitable for high-throughput screening of low-molecular weight contaminants in milk. Since this method provides only preliminary qualitative results, chromatographic methods must be used for confirmation. Moreover, the integration of QDs and broad-specificity MAbs will allow simultaneous analysis of structurally different species of multiple low-molecular weight compounds in a single well.