The brightest dots in the bunch

Quantum dots (QDs), fluorescent inorganic crystals <10 nm in diameter, offer several advantages over organic dyes for labeling biological samples. They resist photobleaching, and their emission spectra are narrow enough that multiple variants (excited by one wavelength) can be distinguished in a given sample. The feasibility of using QDs for biological uses is proven in two recent articles by Jyoti Jaiswal, Sanford Simon (Rockefeller University, New York, NY), and colleagues and by Xingyong Wu, Marcel Bruchez (Quantum Dot Corporation [QDC], Hayward, CA), and colleagues. “Quantum dots were offered up as a savior for protein labeling a couple of years ago,” says Simon. “But it hadn't been shown that they could be used in vivo.”

The QDC group shows that QDs can be used to label proteins in fixed and living cells. Using...