Hi Sean,
Don't know of an alternative that can do what you want.  I would think that the same properties of a surfactant that make it one would also disturb lipid layers.  

Aside from that, I would caution against the assumption that fixation without detergent allows only exterior staining.  The fixation process will also open holes in membrane and allow Ab to penetrate.  At least test it before committing to that route.  The best result I've had restricting immunostaining to a surface is to stain live material, then fix after washing.
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 Sean Speese
Sent: Tuesday, January 04, 2011 5:44 PM
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Subject: Question about surfactants to break surface tension

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Hi all,
   Bit of an off topic question, but we do lots of immunos on small bits of Drosophila tissue that always float on top of the fix due to the surface tension.  We can use low amounts of triton (.01%) to overcome this, but I would like to be able to leave detergents out until I am convinced the fixation is good.  In some cases I would like to do staining of only things on the cell surface, and thus need to leave detergents completely out of the staining procedure.  Therefore, does anyone know of a good surfactant that would break the surface tension but not permeabilize cells?

Thanks, 
   Sean Speese