Fwd: RE: [3dem] Contamination problem on cryo grids

[Norm Olson]

>
>Dear Anselm,
>
>This looks very much like a hydrophobicity problem. The support is 
>not hydrophilic enough, preventing the water to spread nicely over 
>the film and the holes.
>
>I encountered this as a typical Quantifoil problem, since I (and 
>others) noted that there is residual plastic.
>

-- 
I have been reading this thread with a great deal of interest.  It 
seems like everyone has their own way things should be done but I 
have not seen any studies, I could have missed them, where controlled 
tests were performed.  Carbon films have always had somewhat of a 
"religion" around them but with the manufactured holey carbons it 
seems like it has gotten worse.  As an example, Quantifoils need to 
be treated to remove the manufacturing plastic, to reduce 
beam-induced charging, to reduce contamination, or to make the films 
more hydrophilic.  Is any of that correct? Maybe all of it is 
correct, who knows.  On the other hand, how many people are there out 
there who don't treat them in solvents at all?  Others I have talked 
with say that the C-flats give more of an even ice thickness because 
they don't have plastic but they still do charge which seems to 
contradict others who say that the plastic causes beam-induced 
charging.  Some people have told me that it is necessary to go 
through several different solvents, others have their one favorite 
solvent.

Just my observations from the bleacher seats....

Norm

______________________________________________________________
Norm Olson
Cryoelectron Microscopy Facilities Manager
1510 Bonner Hall
Department of Chemistry & Biochemistry, MC-0378
University of California San Diego
La Jolla, CA 92093-0378
nholson at ucsd.edu
http://cryoem.ucsd.edu
Cell:  (858)220-2183
(858)822-6718 - Office; (858)534-5846 - Fax
______________________________________________________________