| Abstract: | An immunoassay for Escherichia coli O157:H7 using quantum-dot (QD) labeling and subsequent release of the QD labels from immunocomplexes has been developed. The assay principle is that anti-E. coli O157:H7 conjugated immunomagnetic beads are used to capture E. coli O157:H7; this is followed by the binding of QD labeled antibodies to form sandwich immunocomplexes (Bead-Cell-QD); a dissociation buffer then elutes QDs from immunocomplexes by denaturing antibody or lysing cell; the fluorescence signal of the eluted QDs is measured to quantify E. coli O157:H7. This proposed approach avoids the interference of bead autofluorescence in signal transduction and, thus, enhances the detection resolution, while keeping the fast magnetic separation and sandwich binding of two selective antibodies for high specificity. |
