Bio-Rad Trans-Blot® SD Semi-Dry Transfer Cell - Manual (Page 12)

7. Carefully place the cathode onto the stack. Press to engage the latches with the guide
posts without disturbing the filter paper stack.
8. Place the safety cover on the unit. Plug the unit into the power supply. Normal transfer
polarity is cathode to anode, i.e., red wire to red outlet and black wire to black outlet on
the power supply.
Caution: Do not reverse polarity. This will result in damage to the stainless steel cathode.
9. Turn on the power supply. Transfer mini gels for 15–30 minutes at 10–15 V. Large gels
can be transferred for 30 minutes to 1 hour at 15–25 V. Do not exceed 25 V with this
instrument. A current limit (3 mA/cm
2 for large gels; 5.5 mA/cm 2 for mini gels) is
recommended to prevent excessive heating during the run. Under the strong fields
developed by this apparatus, transfers may not always be quantitative. A certain quantity
of protein may be transferred through the membrane and onto the filter paper below.
The Model 200/2.0 power supply is capable of a 200 watt output. This means that unless
a current limit is set, uncontrolled conductivity changes may result in full power being
delivered to the Trans-Blot SD cell. In this situation, the gel sandwich and electrodes will
be exposed to excessive heat. This may result in a safety hazard. It is advisable to monitor
resistance, power, and current during the run. Refer to the Model 200/2.0 Instruction
Manual for setting current limits and run times, and monitoring these parameters.
10. Following transfer, turn the power supply off, and disconnect the unit from the power
supply. Remove the safety cover and the cathode assembly. Discard the filter paper (and
dialysis membrane, if used). The transfer efficiency can be monitored by staining the gel
with Coomassie blue R-250 protein stain or with Bio-Rad's Silver Stain Kit. Alternatively,
prestained molecular weight standards can be used, or a portion of the membrane can be
stained for total protein with colloidal gold, Biotin Blot Total Protein Stain, or an anionic
dye such as Amido Black. Zeta-Probe membrane can be stained with the Biotin-Blot
Total Protein Stain.
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