Peering into Cellular Worlds
By Emily Singer
Fluorescent tags have been designed for a myriad of proteins. But many of the current tags have problems: they fade easily, or they don’t come in enough colors to study many different proteins at once. A new type of fluorescent tag, made up of nanometer-size crystals known as quantum dots, could solve those problems. Scientists can create quantum dots in a rainbow of colors. And because quantum dots of all colors can be excited by the same wavelength of light, scientists can use them to examine a multitude of protein molecules simultaneously.
The image at left is a mouse small intestine labeled with red and green quantum dots that target two types of proteins, and with a dye that stains cell nuclei blue.