aqueous gel sample prep

April 18, 2007 at 4:46 pm | | everyday science, science community

Does anyone have any experience making samples (preferably thin-film, ~100 nm) using agarose, gelatin, or some other transparent aqueous gel/biopolymer? For my poly(methyl methacrylate) samples, I spin-coat at 2500 RPM for 30 s and get a ~30-nm film. I can experiment with conditions, but I thought I’d ask first.

I’m trying to measure fluorescence from a relatively concentrated sample (~10-6 M fluorophore in biogel) on a glass coverslip using epi-illumination.

If I get any answers, I’ll let you know here.


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  1. Person X says:

    Do you really need 100 nm? Squeezing gelatin between two cover slips will make a pretty thin sample, probably a micron or a few microns. If you use quartz slips, which are flatter, it will be even thinner.

    That sounds pretty reasonable.

    Comment by sam — April 18, 2007 #

  2. Mmmm, for polymer films I dissolve in chloroform then evaporate the solvent either ambient, under vacuum or under nitrogen. More dilute, thinner film. I’m not sure how well that would work on your biopolymer though – if you need it hydrated it really wouldn’t work. Sometimes cast films on to teflon sheets if that helps any, often by pipetting out solutions, but sometimes by spraying from an atomizer (difficult to get even coverage).

    Comment by Propter Doc — April 18, 2007 #

  3. Yeah, chloroform wouldn’t work: I need aqueous. Thanks, though.
    I guess I’ll have to go with a thicker film (~1 um), which should work fine.

    Comment by sam — April 19, 2007 #

  4. Agarose and gelatin set into gels by cooling. You’ll have to cool the coverslip as you spin it.

    Comment by Jordan — April 22, 2007 #

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