Anyone know about flourescent dyes?

[johnintheuk]

I'm looking for dyes that have exceptionally high quantum yields and minimal photobleaching rates.

So far, perylene based dyes seems to be the best. Their yield approaches 100% and exhibits the low photobleach rates I mentioned.

Quantum dots have reasonable yield and great photobleach rates compared to most dyes.

Anyone understand the photobleaching mechanisms in more detail? I realize there is a photoxidation factor, which caused the dye / dots to oxidize under photo exposure. But even when oxygen is excluded, many dyes (dots included) appear to bleach out of fluorescence somehow. I've seen it mentioned that this is caused by intense excitation causing triplet states to appear. I'd be interested to know if this means the material becomes locked in some forbidden decay state that prevents flourescence, if the state would decay and return to normal again over time or if the materials are denaturing in some other permanent manner due to the triplet state being available.

Know of any others dyes I could look at?

 

[Andy Resnick]

The confocal listserver just had a discussion about photobleaching. I didn't understand all of the details, but I think it had to do with excited triplet states somehow strongly interacting with (reactive) singlet oxygen species, which ultimately degrades the dye.

Quantum dots, due to a different fluorescence mechanism (excitation of confined electrons rather than excitation of molecular bound states) don't photobleach, IIRC.

What is your application?