Figure 5. Fluorescence intensity and emission spectra of QD–streptavidin
conjugates. (A) Fluorescence intensity comparison between Alexa
568–streptavidin and QD 608–streptavidin. Mouse kidney sections were
stained with ANA, anti-human IgG-biotin, and Alexa 568–streptavidin or QD
608–streptavidin to label nuclear antigens. Filter set ex 560 27.5 nm /em
605 10 nm was used to detect both Alexa 568 and QD 608. Filter set ex
460SP/em 605 10 nm was also used to optimize detection of QD 608.
Images were captured from positively stained and control specimens with
the same gain and exposure time. The mean fluorescence intensities were
analyzed with Scion Image software (Scion Corporation, Frederick, MD) and
plotted with Microsoft Excel. (B) Emission spectra of QDs used in the
labeling experiments of this report.