Dec 6, 2002 Quantum dots target breast cancer A US company has
used fluorescent quantum dots to label breast cancer cells for
the first time. Quantum Dot Corporation says that its Qdot
technology offers several advantages over organic dyes
traditionally used for cellular imaging. (Nature Biotechnology
to appear) One advantage is that the Qdots can be fine-tuned to
emit different wavelengths simply by altering the size of the
core nanostructure. Varying the size of the spherical cadmium
selenide (CdSe) core shifts its light emission between 500 and
660 nm. For example, a 3-nm CdSe core emits green light (520 nm)
while a 5.5-nm CdSe core emits red light (630 nm). A protective
shell of zinc sulphide is then applied making the device up to a
standard 8 nm. A second benefit is that either a single
wavelength or broadband source can be used to excite the Qdots.
"The excitation wavelength has to be shorter than the emission
wavelength," Andy Watson, the company's vice president for
business development told Optics.o