New fluorescent labels for time-resolved detection of biomolecules.

New dyes with characteristic fluorescence lifetimes have been developed for bioanalytical applications. Based upon the concept of "multiplex dyes," we have designed rhodamine dyes with nearly identical absorption and emission spectral characteristics but different fluorescence lifetimes. Extending this principle to applications with laser diodes, new rhodamines with functional groups for covalent coupling of analytes have been developed. The new labels exhibit absortion and fluorescence beyond 600 nm and have a high quantum efficiency, even in aqueous buffer systems.