APPLICATIONS OF TECHNOLOGY:

• Imaging cellular structures
• Cell motility and migration assays
• Delivering compounds to cells or subcellular compartments
• Studying cellular pathways and behavior such as protein trafficking, uptake, absorption and division

ADVANTAGES:

• Enables semiconductor nanocrystals to enter the cell nucleus and organelles
• Creates a population of labeled cells containing signal peptide-semiconductor nanocrystal conjugates
• Short cell-conjugate contact enables quicker imaging results
• Compatibility with many linking agents permits targeting of different cellular compartments
• Like other quantum dots:
  • Can be used in live cells
  • Nontoxic, long-term imaging platform for observing cell nuclear processes
  • Does not interfere with natural physiology of cell

ABSTRACT:

Drs. Fanqing Chen and Daniele Gerion from Berkeley Lab have functionalized semiconductor nanocrystals, or quantum dots, with small signal peptides to target specific cellular compartments. Berkeley Lab's signal peptide-nanoparticle conjugates are the first semiconductor nanocrystal complexes to be able to enter the cell nucleus, endoplasmic reticulum, Golgi bodies, and other intracellular organelles. Compared to present technologies, the signal peptide-nanoparticle conjugates are more stable and are compatible with a greater number of linking agents. This enables enhanced targeting of cell organelles for cargo delivery or imaging. For instance, a mitochondria-targeting signal peptide can be functionalized to the Berkeley Lab probes to target the mitochondria exclusively. They also have the advantages of low cytotoxicity and higher sensitivity, as compared to organic dyes. In addition, they have desirable photostability, long-term biological stability, and reasonable resistance to aggregation within in the cell. The surface chemistry of the semiconductor nanocrystals allows the escape of the conjugates from endosomal/lysosomal pathways in living cells. The Berkeley Lab conjugates do not interfere with the growth or differentiation of the cells and therefore they can be retained by the cell population for extended periods of time.

For use in the imaging of cellular structures, the conjugate is first taken up by the cell. The cell is then imaged to track the movement of the conjugates within the cell. For imaging within the nucleus, a nuclear localization signal (NLS) peptide can be fixed to the semiconductor nanocrystal, allowing the conjugate to be transported by the nuclear trafficking proteins and to interact with the nuclear pore complex. The conjugates are small enough in diameter (less than about 20 nm) to enter the nucleus.

STATUS:

• Available for licensing or collaborative research.

To learn more about licensing a technology from LBNL see http://www.lbl.gov/Tech-Transfer/licensing/index.html.

FOR MORE INFORMATION:

Liu, G.L., Kuncharkarra, S., Mukherjee, B., Gerion, D., Jett, S.D., Bear, D.G., Gray, J.W., Alivisatos, A.P., Lee, L.P., Chen, F.F., "A nanoplasmic molecular ruler for measuring meclease activity and DNA footprinting." Nature Nanotechnology. Vol. 1. Oct. 2006, 47-52.

REFERENCE NUMBER: IB-2045

SEE THESE OTHER BERKELEY LAB TECHNOLOGIES IN THIS FIELD:

• Molecular Ruler for Label-free Measurement of Protein-DNA Interactions, IB-2320