Production and Targeting of Monovalent Quantum Dots
DOI: 10.3791/52198-v
What you'll learn
✓Prepare monovalent quantum dots via DNA wrapping without purification
✓Transfer quantum dots from organic to aqueous phase
✓Label live cells using SNAP-tag targeting for fluorescence imaging
✓Apply quantum dots for cell-surface receptor visualization
Protocol
We provide detailed instructions for the preparation of monovalent targeted quantum dots (mQDs) from phosphorothioate DNA of defined length. DNA wrapping occurs in high yield, and therefore, products do not require purification. We demonstrate the use of the SNAP tag to target mQDs to cell-surface receptors for live-cell imaging applications.
Difficulty
advanced
Total time
~4–6 hours (including phase transfer, DNA conjugation, and cell labeling)
Model organism
HEK293 (or equivalent mammalian cell line with SNAP-tag expression)
Biosafety
BSL-1
Steps
1
Transfer quantum dots to aqueous phase
Convert quantum dots from organic solvent to water-soluble form via phase transfer. This prepares QDs for subsequent DNA conjugation.
▶ 02:38
2
Prepare monovalent targeted quantum dots
Wrap phosphorothioate DNA of defined length onto quantum dots to create monovalent conjugates. High-yield reaction requires no purification.
▶ 04:21
3
Label live cells with monovalent quantum dots
Incubate live cells expressing SNAP-tag receptors with mQD-DNA conjugates to enable cell-surface targeting and live-cell fluorescence imaging.
▶ 06:43
4
Visualize quantum dot labeling of SNAP-proteins
Image labeled cells to confirm monovalent QD targeting to SNAP-tagged cell-surface receptors. Demonstrates successful protocol outcome.
▶ 08:06
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