With the rapid developments in the life sciences and the emer-
gence of a large number of substances for analysis, bioanalytical
techniques have faced unprecedented challenges and high-
throughput screening techniques are called for urgently. 1–4
Compared with conventional assay technologies, such as planar
arrays, 5–7 bead-based suspension assays provide more molecular
binding sites and effectively improve the sensitivity, and thus
have become more and more intriguing. 8–12
A key technology of bead-based assays is how to obtain a large
number of encoded and distinguishable microbeads. Fluores-
cence barcoding technology based on organic fluorophore-
encoded microbeads has attracted considerable attention for
multiplexed gene and protein screening. 9,13–18 However, poly-
meric beads optically encoded with organic fluorophores have
many limitations, such as photobleaching and the narrow exci-
tation spectra of dyes. QDs, a type of newly developed inorganic
nanocrystal, have become a promising fluorescent material used
to encode the beads, which has further promoted the develop-
ment of fluorescence encoded bead-based multiplexed analysis
technology. 17,19 Taking conventional organic dyes for