Formation of water-soluble carboxyl-functionalized QDs and
labeled antibodies
We have previously thoroughly described water-soluble CdSe/
ZnS PMAH-QDs and their reaction mechanism (Shen et al., 2011a,
2011b, 2012). Based on the TEM characterization (Fig. 2A), the
PMAH-QDs presented a narrow size distribution and high mono-
dispersity, with an average size at approximately 25 nm. The dy-
namic light scattering analysis in Fig. 2B shows that the hydro-
dynamic size of PMAH-QDs before conjugation is 46.7 nm, and this
size increased to 145 nm after conjugation with antibodies, which
indicates the successful conjugation of antibodies. We also in-
spected the fluorescence properties of the QDs, and the results
showed that absorption was maximized at 365 nm, whereas
emission was maximized at ?620 nm; these peaks were ap-
proximately symmetric (Fig. 2C). Furthermore, little overlap was
observed between the absorption and emission spectrum, in-
dicating excellent fluorescence properties.