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1 |
Zeiss Immersion Medium "Immersol" W, 20ml in oiler |
FF5000000-1252-136 |
Zeiss UK |
£ 57.00 |
Hi Cam,
I had a respective problem on our multiphoton microscope. Someone at last years FOM suggested to use eye gel. So I ordered a collection of various eye gels and Ultrasonic contact gels (is that the English name for it?) from our pharmacy. Price range: 2 - 5 Euro each, for the ultrasonic gel this is for a 500 g bottle....
Inspired by a paper from Guy Cox, I used moss from the lawn in front of the building (the snow finally receded) as a test specimen (moss has no air in the leaves, as have vascular plants), first imaged in water for comparison. It turned out that the eye gel brands I got had horrible optical properties. But the Ultrasound contact gel was not so bad. It even got better when I diluted it 1:5 (or 1:10) in distilled water.
After finding empirically that it works, I started looking for the ingredients. The material data sheet (found on the web) stated it contains 25% 1,2 Propylenglycol, 74% water and 0.9% "Pioneer NP 37". Futher Googleing revealed that the later is a brand name for Na-Polyacrylat = Carboxyvinyl-Polymere, a "Superabsorber"
For Propylenglycol, I found an Ri of 1.432 on the web. For Na-Polyacrylat, I didn't find the Ri, so I ignored it. Assuming I just can obtain the Ri for my 1:5 dilution of the Gel (i.e. 5% Propylenglycol in water) by calculation (0.05*1.432 + 0.95*1.333), it is 1.338 and thus not so very much different from water itself (I know, I know, but I am not going for the diffraction barrier in my application). I found one reference that says the Ri of bovine muscle tissue is 1.382 (Dircks JJ et al, J Biomed Opt. 2005, 10:44014), so what the sample is doing to the optical path is probably much worse than what this diluted gel is doing. (Makes me wonder if we should ask companies for objektives made for that Ri). Anyway, I am aware that this is a pretty crude calculation with errors and unsubstantiated assumptions, but the point is, I get images which fullfill the needs we have.
A note of caution: I use this now for a few weeks only, so my practical experience is limited. the 1:5 dilution still slowly flows away, but at a speed such that it is not a problem to "refill" in time.
I don't think you will get this particular brand in Australia, but just for completeness the details:
Ultraschall-Kontakt-Gel Wasserfuhr, from Caesar & Loretz, D-40721 Hilden.
Diluting the Gel in 0.9 NaCl is not working: Apparently the ions lead to a structural break-down of the gel.
And another note: Zeiss is selling something called "Immersol W" which is supposed to be viscous and have the Ri of water. No experience with that one, I guess it can't beat the price of the Ultrasonic gel, though.
Let us know if you find alternatives.
Steffen
At 23:37 22.03.2009, you wrote:
Hi List,<http://www.ludwig.edu.au/branch/research/platform/microscopy.htm>Facility Website
Has anyone had any experience in using optical gels? We are looking at imaging lymphatic vessels in a mouse tail (still attached to a live mouse) and eventually lymph nodes with our two photon system. The scope is fitted with a 20x water immersion lens (NA 0.95) but we don’t want to submerge the whole tissue. So ideally we need a thick gel that has the same RI of water and won’t damage the objective.
I found one paper (Rothstein et al.) that use sorbitol gelled with carbomer 940 to create a gel with a refractive index similar to water. Is there any other gels that anyone has used before? I was thinking of acrlyamide (polymerised) but cannot find the RI of it.
Cheers
Cam
Cameron J. Nowell
Microscopy Manager
Centre for Advanced Microscopy
Ludwig Institute for Cancer Research
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Royal Melbourne Hospital
Victoria, 3050
AUSTRALIA
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Steffen Dietzel, PD Dr. rer. nat
Ludwig-Maximilians-Universität München
Walter-Brendel-Zentrum für experimentelle Medizin (WBex)
Head of light microscopy
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