Quantum-dot-tagged microbeads for multiplexed optical coding of biomolecules

Mingyong Han, Xiaohu Gao, Jack Z. Su, Shuming Nie

Research output: Contribution to journalArticlepeer-review


Multicolor optical coding for biological assays has been achieved by embedding different-sized quantum dots (zinc sulfide-capped cadmium selenide nanocrystals) into polymeric microbeads at precisely controlled ratios. Their novel optical properties (e.g., size-tunable emission and simultaneous excitation) render these highly luminescent quantum dots (QDs) ideal fluorophores for wavelength-and-intensity multiplexing. The use of 10 intensity levels and 6 colors could theoretically code one million nucleic acid or protein sequences. Imaging and spectroscopic measurements indicate that the QD-tagged beads are highly uniform and reproducible, yielding bead identification accuracies as high as 99.99% under favorable conditions. DNA hybridization studies demonstrate that the coding and target signals can be simultaneously read at the single-bead level. This spectral coding technology is expected to open new opportunities in gene expression studies, high-throughput screening, and medical diagnostics.

Original languageEnglish (US)
Pages (from-to)631-635
Number of pages5
JournalNature Biotechnology
Issue number7
StatePublished - Jul 2001
Externally publishedYes

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Applied Microbiology and Biotechnology
  • Molecular Medicine
  • Biomedical Engineering

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