Quantum dots are semiconductors whose electronic properties depend upon their size and shape. Their surfaces can be functionalized with biomolecules such as DNA and proteins, or with small molecules, opening the possibility for their uses as drug delivery agents.

Zong-Wan Mao and co-workers, Sun Yat-Sen University, China, report that quantum dots can also be used to deliver the gene regulation agent small interfering RNA (siRNA).

Quantum dots coated with β-cyclodextrin were taken up by living cells and remained localized in vesicles in the cytoplasm. siRNA’s gene-silencing efficiency was improved compared with current siRNA delivery methods. Cellular toxicity was significantly reduced. This delivery system improves siRNA’s therapeutic potential and could allow visible imaging of siRNA delivery.

• Targeted Cellular Uptake and siRNA Silencing by Quantum-Dot Nanoparticles Coated with b-Cyclodextrin Coupled to Amino Acids
  M.-X. Zhao, J.-M. Li, L. Du, C.-P. Tan, Q. Xia, Z.-W. Mao, L.-N. Ji,
  Chem. Eur. J. 2011.
  DOI: 10.1002/chem.201003523