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   Alice Y. Ting

Single-molecule imaging and fluorophore design

Single-molecule imaging has revolutionized biology by allowing scientists to visualize and study the heterogeneous, non-averaged behavior of biomolecules in vitro and inside cells. Single-molecule imaging also underlies several new optical super-resolution imaging techniques (e.g., STORM and PALM). To faciliate single-molecule imaging, our lab is interested in (1) developing new and improved fluorescent probes, and (2) developing new methods to target these probes to specific proteins in the cellular context.

One specific class of probes that has captured our attention is quantum dots (QDs). QDs are widely appreciated for their exceptional photophysical properties – intense brightness, photostability lasting for hours – that make them ideal for single-molecule imaging. Yet cell biologists have been slow to embrace QDs, because of their large size, their multivalency, their membrane-impermeability, and the difficulty of targeting them to specific cellular proteins. Our lab has been working to remove each of these barriers, so that QDs can be used routinely for single-molecule imaging in live cells.

Related publications:

Monovalent, reduced-size quantum dots for imaging receptors on living cells.
Nature Methods 2008, 5, 397-399.
M. Howarth, W. Liu, S. Puthenveetil, Y. Zheng, L. F. Marshall, M. M. Schmidt, K. D. Wittrup, M. G. Bawendi, and A. Y. Ting.

Compact biocompatible quantum dots functionalized for cellular imaging.
Journal of the American Chemical Society 2008, 130, 1274-1284.
W. Liu, M. Howarth, A. B. Greytak, Y. Zheng, D. G. Nocera, A. Y. Ting, and M. G. Bawendi.

Phage display evolution of a peptide substrate for yeast biotin ligase and application to two-color quantum dot labeling of cell surface proteins.
Journal of the American Chemical Society 2007, 129, 6619-6625.
I. Chen, Y.-A. Choi, and A. Y. Ting.

Targeting quantum dots to surface proteins in living cells with biotin ligase.
Proceedings of the National Academy of Sciences 2005, 102, 7583-7588.
M. Howarth, K. Takao, Y. Hayashi, and A. Y. Ting.

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