Gone are the days when "multicolor immuno-fluorescence" meant proteins tagged with dyes of red, green, and blue. Today's fluorescent molecules cover the color spectrum, and researchers are using them to image proteins simultaneously.
Antibodies can be conjugated to two types of fluorescent molecules: organic fluorophores, or dyes, and quantum dots. Dyes, which link to antibodies that directly or indirectly recognize desired proteins, have been a staple in immunfluorescence studies for decades. That means many antibodies are commercially available and protocols are versatile. But dyes have drawbacks for multiplexing. An activated dye emits a wide spectrum of light outside its peak emission level, creating overlap when several are used at once. And absorption spectra are narrow, so a separate laser is needed to excite each dye.
Quantum dots avoid these difficulties. Dots are 20 to 50 times brighter than dyes and emit narrow spectra, and color can be finely tuned by ...
