IgG molecules are widely used for bioconjugation in fluorescence
labeling. It was earlier demonstrated that QDs can be linked to IgG
and that the resulting QD-IgG complex is capable of binding specific antibodies to form aggregates in solution3. However, it has not
been shown that QD-IgG probes can label cellular targets. To investigate the ability of QD-IgG probes to label a specific cellular target, we
attempted the detection of Her2, a cancer marker overexpressed on
the surface of some breast cancer cells14–16, with QD 535 (QDs with
emission maximum at 535 nm) and QD 630 conjugated to antimouse IgG. The QD-IgG probes successfully labeled Her2 on the
surface of human SK-BR-3 breast cancer cells after the cells were
incubated with a monoclonal anti-Her2 antibody that binds to the
external domain of Her2 (Fig. 1A, 1C). When cells were incubated