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Microminiaturized immunoassays using quantum dots as fluorescent label by laser confocal scanning fluorescence detection

Authors
Journal
Journal of Immunological Methods
0022-1759
Publisher
Elsevier
Publication Date
Volume
249
Identifiers
DOI: 10.1016/s0022-1759(00)00331-8
Keywords
  • Fluorescent Label
  • Immunoassay
  • Quantum Dots
  • Sandwich Assay
Disciplines
  • Physics

Abstract

Abstract An immunoassay readout method based on fluorescent imaging analysis with laser confocal scanning is described. The ZnS-coated CdSe quantum dots (ZnS/CdSe QDs) were linked to a detection antibody. Immunoassay was carried out on a glass chip using a sandwich assay approach, where antibody covalently bound to a glass chip was allowed to capture antigen specially. Afterwards, the detection antibody labeled with QD was allowed to bind selectively to the captured antigen. The fluorescent signals of the sandwich conjugate were detected by a laser confocal scanner. A diode laser was used to excite efficiently the fluorescent signals while bovine serum albumin was used to eliminate nonspecific binding sites. The detection limit of this approach was up to 10 −9 M under current experimental conditions. The specificity of the QDs-labeled immunoglobulin (IgG) was tested by an experiment using goat IgG and human IgG samples. The result was consistent with the binding specificity in a sandwich-type assay. The potential of this method to function as a simple and efficient readout strategy for immunoassay in biochip is discussed.

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