Hi Martin,
I just went through the effort of finding some uranyl glass to use as a fluorescent standard for a 2P imaging system.  The biggest difficulty was finding some.  After searching for and calling various commercial concerns, I managed to get a couple of pieces from scrap that the glassblowers in the Chemistry Dept. had stashed for special use.  Any idea on current sources of this material?  
Cheers,
C


Carl A. Boswell, Ph.D.
Molecular and Cellular Biology
Univ. of Arizona
520-954-7053
FAX 520-621-3709


-----Original Message-----
From: Confocal Microscopy List [mailto:[log in to unmask]] On Behalf Of Martin Wessendorf
Sent: Thursday, June 02, 2011 2:12 PM
To: [log in to unmask]
Subject: Re: Fluorophore excitable with 405nm and 488nm lines

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Dear Daniel--

On 6/2/2011 1:59 PM, Daniel Gitler wrote:

> I am in need of either beads or a fluorophore in solution which is exited consistently by both the 405nm and 488nm lines of a confocal microscope. What I really need is that the ratio of excitation should be constant, in which case two separate dyes are probably not a good choice, unless their molar ratio can be quite consistent (perhaps in beads?). I also need that the efficiency of excitation for both lines be quite decent (doesn't have to be maximal, just decent). Finally (it appears I have a lot of requisites) the dye/beads should be as insensitive as possible to environmental changes (i.e., pH etc). The idea is to have a good standard in order to calibrate the ratio of the power of these two lines when imaging a sample (I do not need to know the actual number, just a relative measure will do fine).

Based on a quick search, uranium glass looks like a possibility.  The absorbance is perhaps 2x better at 488 than 405.  However, if you're imaging with a confocal, you would probably need to use point-scanning, since uranium has a loooong fluorescence time-constant (e.g. 170 usec in solution).

Here are a few (mediocre) references--they might be a starting point:

http://pubs.acs.org/doi/abs/10.1021/ac00230a029
http://webhost.bridgew.edu/cnoda/research/uranyl/index.html
http://onlinelibrary.wiley.com/doi/10.1002/pssa.2211150136/pdf

Good luck!

Martin
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