Bio-Rad Trans-Blot® SD Semi-Dry Transfer Cell - Manual (Page 10)

Low molecular weight macromolecules ( 10,000 daltons) may diffuse out of gels more
readily. One can allow adequate gel pre-equilibration by changing the pre-equilibration
buffer several times during a relatively short pre-equilibration period. This will help to limit
diffusion of low molecular weight macromolecules while providing efficient salt reduction.
3. Cut the membrane to the dimensions of the gel. Wet the membrane by slowly sliding it
at a 45° angle into transfer buffer and allowing it to soak for 15–30 minutes. Complete
wetting of the membrane is important to insure proper binding. Abrupt wetting can lead
to entrapment of air bubbles in the matrix. These air bubbles can block transfer of
molecules. To avoid membrane contamination, always use forceps or wear gloves when
handling membranes.
4. Cut filter paper to the dimensions of the gel. Two pieces of extra thick filter paper (or
four pieces of thick or six pieces of thin filter paper) per gel are needed for each gel/mem-
brane sandwich. Completely saturate the filter paper by soaking in transfer buffer.
5. If more than one full-size gel is to be transferred at one time, cut a piece of dialysis
membrane with the appropriate molecular weight cutoff to the dimensions of the gel.
Completely wet the dialysis membrane in transfer buffer. Spectr/Por™ dialysis
membrane is recommended for this use.
4.2 Assembly of the Unit for Standard Transfers
Wear gloves for this procedure to avoid contamination of membranes.
1. Remove the safety cover and the stainless steel cathode assembly.
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