Mr. Subach,

Please pay attention to this book:

https://www.springer.com/de/book/9780387312781.

Hello Ivanova,

thank you for your kind update. If you know of a particular chapter/section of this text addressing my question feel free to email.

Much Thanks:)

Joel

I second the book recommendation, it's clear and extensive.

Fluorescence is a very fast process and does not extend beyond hundreds of nanoseconds. That means the fluorescence is complete before you could move your hand to reach for the syringe! Before you could think to move your hand!!

There is a related phenomenon called phosphorescence that is longer lived, and this can persist for microseconds to minutes (glow in the dark toys are an example of long-lived phosphorescence). The difference between the two comes down to quantum mechanics and is operationally not important to your project. Both are light in light out processes.

How long something will emit light is not always to easy to predict. Certain environments will steal the energy from the excited state molecule (quench) such that emission is no longer seen. Water is great at this for a lot of molecules.

If you have to image through tissue, I would recommend looking into fluorescence up-converters. These are excited at longer wavelengths than their emission and sometimes work well for tissue, since tissue is transparent to some wavelengths of IR light and can be more easily excited by it without the need for pre-injection excitation of a dye. Without more details, that's the best I have for you. Hope that helps, best of luck!

Hi Jeremy and thank you for your kind update.

I am assuming in your statement 'microseconds to minutes' meant maybe several minutes maximum?

Accordingly, I am inferring that deep in vivo tissue with tagged stimulated fluorochrome must be continually stimulated ex vivo since via the time it reaches its tissue it will be relaxed without further light stimulus. If theres another way feel free to enlighten me, thanks:)

Hi Joel,

I wouldn't expect more than minutes. There might be some really long emitter out there, but generally anything that has really extreme properties is impractical to work with! Yes, continual stimulation is the standard practice.

I see you're at Rutgers, I was for my PhD. I was helping a grad student in biomedical engineering take some basic measurements on nanoparticles he was using to images something or other in rats. You can try pinging him directly (@Dominik Naczynski) on researchgate, check out some of his papers, or see if you can get some of his advisor's time (Prabhas Moghe). They will be able to help you much better than I can. I believe they were using a 980 nm cw laser for their work.

Hello and ok Jeremy thanks a bunch:)

Hi Joel,

Fluorochrome or DiOC6(3) displays a wide range of lifetimes in the cytoplasm, ranging from 0.4 to 1.0 ns depending on its binding locale. As Jeremy said, fluorescence life-time of biological dye and tissues is very short. The emission goes away the moment you stop the irradiation. Possibly not important here, the other kind of emission that have longer life-time from minutes to hours (because electron is in triplet transition stage under electromagnetic radiation) is phosphorescence.

You may want to check this out : Forward-collected simultaneous fluorescence lifetime imaging and coherent anti-Stokes Raman scattering microscopy.

This one summarizes some options for dye to use: Fluorescence Lifetime Measurements and Biological Imaging

Hello Du and thank you much for your update, I will follow your update accordingly.

Best,

Joel