Potentials and pitfalls of fluorescent quantum dots for biological imaging

doi:10.1016/j.tcb.2004.07.012

Trends in Cell Biology

Volume 14, Issue 9, September 2004, Pages 497-504

https://doi.org/10.1016/j.tcb.2004.07.012 Get rights and content

Fluorescent semiconductor nanocrystals, known as quantum dots (QDs), have several unique optical and chemical features. These features make them desirable fluorescent tags for cell and developmental biological applications that require long-term, multi-target and highly sensitive imaging. The improved synthesis of water-stable QDs, the development of approaches to label cells efficiently with QDs, and improvements in conjugating QDs to specific biomolecules have triggered the recent explosion in their use in biological imaging. Although there have been many successes in using QDs for biological applications, limitations remain that must be overcome before these powerful tools can be used routinely by biologists.

Section snippets

Utility of QDs in bioimaging

In this section we discuss the properties of QDs that make them a desirable alternative to organic fluorophores and highlight their advantages for biological imaging.

Potentials of QDs as fluorescent probes in biology

In this section we discuss how the potentials of QDs for biological imaging are being realized. Box 2 describes how QDs have been used for sensitive multicolor assays of biomolecules in vitro. The techniques for using QDs to detect the presence and activity of biomolecules, for labeling proteins and cells with QDs, and for carrying out long-term live cell imaging are described below.

Pitfalls of QDs as probes in biology

Despite their potential and their success so far in biological applications, QDs also have limitations associated with their use. Box 3 discusses one of the chief impediments to their use – that is, their effective delivery into cells. In this section we discuss the properties of QDs and QD bioconjugates that need to be improved before the full potential of these inorganic fluorophores can be realized in terms of biological applications.

Concluding remarks – what lies ahead?

The potential value of QDs in bioimaging is due to (i) their photostability, which facilitates the long-term tracking of QD-labeled cells and molecules; (ii) their ability to tune emission wavelength, which enables them to tag simultaneously several different population of cells and molecules; (iii) their broad excitation and narrow emission spectra, which facilitates the simultaneous detection of different QD-tagged cells; and (iv) the availability of common approaches to bioconjugate them

Acknowledgements

This work was supported by the Defense Advanced Research Project Agency, the National Science Foundation (BES-0119468 and BES 0110070) and the National Institutes of Health (P20 GM072015-0). We thank Joshua Rappoport, Marina Fix and the reviewers for their helpful comments.

Glossary

Fluorescence blinking:: a property of a single fluorophore to transit between a fluorescent (on) and non-fluorescent (off) phase, which is caused by its transition between a singlet (fluorescent) and a triplet (non fluorescent) state. Blinking occurs in quantum dots because a specific process causes them to switch between their ionized and neutralized states.
Multiphoton microscopy:: a process in which more than one photon, each with a fraction of the energy needed to excite fluorescent molecules,

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View full text

Trends in Cell Biology

Potentials and pitfalls of fluorescent quantum dots for biological imaging

Section snippets

Utility of QDs in bioimaging

Potentials of QDs as fluorescent probes in biology

Pitfalls of QDs as probes in biology

Concluding remarks – what lies ahead?

Acknowledgements

Glossary

Lighting up cells: labelling proteins with fluorophores

Nat. Cell Biol.

Self-assembly of CdSe-ZnS quantum dot bioconjugates using an engineered recombinant protein

J. Am. Chem. Soc.

(CdSe)ZnS core-shell quantum dots: synthesis and characterization of a size series of highly luminescent nanocrystallites

J. Phys. Chem.

Selection of quantum dot wavelengths for biomedical assays and imaging

Mol. Imaging

Long-term multiple color imaging of live cells using quantum dot bioconjugates

Nat. Biotechnol.

Multiplexed toxin analysis using four colors of quantum dot fluororeagents

Anal. Chem.

Water-soluble quantum dots for multiphoton fluorescence imaging in vivo

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Nat. Biotechnol.

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