期刊
SCIENTIFIC REPORTS
卷 7, 期 -, 页码 -出版社
NATURE PUBLISHING GROUP
DOI: 10.1038/s41598-017-01022-w
关键词
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资金
- Ministry of Science and Technology, Taiwan [MOST 105-2314-B-038-081-MY3, MOST 105-2622-B-038-003-CC2, MOST 104-2632-B-038-001]
- National Health Research Institutes, Taiwan [NHRI-EX105-10238SC]
- Taipei Medical University, Shuang Ho Hospital, Taiwan [101TMU-SHH-06]
- Comprehensive Cancer Center of Taipei Medical University/Health and Welfare Surcharge of Tobacco Products, Taiwan [MOHW106-TDU-B-212-144001]
The sensitivities of solid-phase immunoassays are limited by the quantity of detection antibodies bound to their antigens on the solid phase. Here, we developed a poly-protein G-expressing bacterium as an antibody-trapping microparticle to enhance the signals of immunoassays by increasing the accumulation of detection antibodies on the given antigen. Eight tandemly repeated fragment crystallisable (Fc) binding domains of protein G were stably expressed on the surface of Escherichia coli BL21 cells (termed BL21/8G). BL21/8G cells showed a higher avidity for trapping antibodies on their surface than monomeric protein G-expressing BL21 (BL21/1G) cells did. In the sandwich enzymelinked immunosorbent assay (ELISA), simply mixing the detection antibody with BL21/8G provided a detection limit of 6 pg/mL for human interferon-alpha (IFN-alpha) and a limit of 30 pg/mL for polyethylene glycol (PEG)-conjugated IFN-alpha (Pegasys), which are better than that of the traditional ELISA (30 pg/mL for IFN-alpha and 100 pg/mL for Pegasys). Moreover, the sensitivity of the Western blot for low-abundance Pegasys (0.4 ng/well) was increased by 25 folds upon mixing of an anti-PEG antibody with BL21/8G cells. By simply being mixed with a detection antibody, the poly-protein G-expressing bacteria can provide a new method to sensitively detect low-abundance target molecules in solid-phase immunoassays.
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