The Mini Trans-Blot Electrophoretic Transfer Cell by Bio-Rad can be used in conjunction with the Mini-PROTEAN for quick and complete SDS-PAGE and blotting applications. In fact, the Mini Trans-Blot cell can be purchased separately or with the Mini-Protean as a complete system. A nice feature of this system is the fact that it is interchangeable: only one tank and lid are needed to both run and transfer gels. The Mini Trans-Blot cell comes with two gel holder cassettes, four fiber pads, a modular electrode assembly, and a “Bio-Ice” cooling unit. The lid and buffer tank may also be purchased if needed. The modular electrode assembly is designed such that either one gel can be transferred alone or two gels can be transferred simultaneously, with a maximum gel size of 7.5 cm x 10 cm. The color-coded gel holder cassettes, module, and electrodes ensure correct assembly of the apparatus during transfer.
I learned how to do Western blots using this system. I have since used other systems, but always end up coming back to this one. The design of this transfer cell makes the transfer of protein and nucleic acids very quick. I routinely do 1 hour transfers at room temperature (using chilled transfer buffer). The Bio-Ice cooling unit eliminates the need for an external cooling source by absorbing the heat generated by the transfer process. However, if an overnight transfer is required, I would definitely place the entire system in a cold room as the Bio-Ice unit will not remain cool enough after a couple of hours or so. The assembled unit must be placed on a stir plate with a stir bar inside of it while transferring to keep the buffer distribution (i.e. temperature of the buffer) even.
Although two gels can be transferred simultaneously, if transfer efficiency and uniformity are important (i.e. quantification applications) then it is better to transfer only one gel. I contacted customer service about this and they said that to transfer two gels, simply double the amperage you would use to transfer one gel. I tried this and got very uneven transfer between the gels. With a 1 hour transfer time, it does not bother me to transfer only one gel at a time. The maximum buffer capacity with the cooling unit in place is 650 ml. Be careful not to overfill as there are holes at the top of the tank that the buffer will leak through. This will not affect your gel but it will make a mess. Bio-Rad also sells a complete line of various compatible buffers for different applications at a reasonable cost.
I currently use the Mini-PROTEAN system for all of my Western blotting applications. Using this system, I have successfully detected numerous proteins, including HIF 1-α, VHL, and HO-1. Although the transfer time has to be optimized for each differently sized protein, this system is pretty quick and the optimization process does not take that long. I have used this system to transfer proteins onto both nitrocellulose and PVDF membranes with no problems. This transfer system, used in conjunction with an alkaline phosphatase substrate kit also made by Bio-Rad, allows me to detect as little 0.0625 ug purified protein consistently.
Ashley Cox, M.S.
Senior Research Assistant
U.S. Army Institute of Surgical Research
Hemostasis Team