Quantum dots are so tantalizing: The nanoscale semiconductor crystals glow more intensely, and for longer time periods, than do fluorescent probes. But their application to biomedicine has been hampered by the facts that they carry toxicity risk and are not water-soluble. Now, however, a coating with a hydrophobic side and a hydrophilic side is allowing quantum dots to be used inside the human body—even inside live cells.1 Researchers at the University of Twente’s MESA+ Institute for Nanotechnology (Enschede, The Netherlands) and at the A*STAR Institute of Materials Research and Engineering (Singapore) are responsible for the innovation, which builds up on the surface of the quantum dot through a process of self-assembly but does not interfere with the dots’ light emission.
The hydrophobic side of the polymer material attaches to the surface of the quantum dot, leaving the hydrophilic side exposed—which makes the quantum dot soluble in water. The exposed side also facilitates binding with other molecules so the coated dots can be made sensitive to certain substances, or to specific types of cells such as tumor cells.
1. D. Jańczewski et al., Nature Protoc., 6, 1546–1553 (2011).