Combining gel filtration and electrophoresis

[Louis Hom]

Do you want this for analytical or preparative purposes?  Do you have any 
rough idea of what particle sizes to expect?  From what I've seen in 
papers describing nonviral gene therapy vectors, even agarose gel 
electrophoresis (which should have larger pore sizes than polyacrylamide) 
only gives a +/- migration into the gel for complexed DNA (i.e., any DNA 
complexes created generally are too big to enter the well, although there 
may be some charge neutralization going on too).

If you feel like you really need an electrophoretic gel exclusion system, 
you should be able to set something up with one electrode at the top of 
the column in contact with the buffer, and the other electrode at the open 
bottom end of the column.  But I would worry about shock hazards.

Basically, you would pour your column, close the valve at the bottom, fill 
the top with buffer, underlay your sample ( e.g., sucrose or glycerol), 
cap the top and stick your electrode in (but you'd need an airtight seal 
around it), then drop the bottom into a collection tube/beaker of buffer, 
open the valve before or after you drop it into the buffer (bubbles could 
be a real pain to deal with), and then insert the other electrode into the 
collection vessel containing buffer.  Actually, you'd need a series of 
collection vessels containing buffer.  Turn on the power, and let it go.  
Sounds like an awful lot of trouble, but it could be done.

If we had a better understanding of what you were trying to achieve, we 
might be able to make better suggestions.
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______________________________________________________________________________
Lou Hom >K'93			     
lhom at ocf.berkeley.edu		
http://www.ocf.berkeley.edu/~lhom/