iBlot™ Dry Blotting System From Invitrogen

If your experiments require you to routinely perform Western blots, then the iBlot™ device from Invitrogen is an affordable, convenient and efficient way to save time when transferring proteins to a membrane. The simple fact of the matter is that the iBlot™ is a dry transfer system that eliminates the need to make transfer buffers and completes the transfer of proteins to a nitrocellulose or PVDF membrane in approximately 5-7 minutes. The iBlot™ consists of simple, easy-to-use controls and program settings and is compatible with E-PAGE mini and midi gels, including Tris-Glycine, Tricine, and Invitrogen’s NuPAGE Bis-Tris and Tris-Acetate gels.

The iBlot™ machine is capable of rapid transfers because of high currents and a short distance between electrodes. The iBlot™ utilizes cathode and anode buffers in a gel matrix along with a copper electrode for transfer. This dry transfer system is supposed to increase protein transfer consistency and lead to higher immunodetection sensitivity than wet blotting methods. Personally, I have not observed any noticeable increases in immunodetection sensitivity (I have not had to change antibody concentrations) compared to our prior wet transfer method. However, its greatest benefit is the time that it saves.

The gel transfer stacks required for the iBlot™ are available as mini stacks, for one gel, or regular stacks, for transferring two gels simultaneously. If you typically run only one gel at a time then the iBlot™ mini stacks can be somewhat expensive ($120 for 10), but the regular stacks, which can transfer two gels, ($150 for 10 stacks/20 gels) are comparable in price to buying nitrocellulose or PVDF membranes and transferring in a conventional method. The major drawback at the present time is that the iBlot™ stacks are only available with nitrocellulose membranes. However, we use PVDF membranes and they can be used either by removing the nitrocellulose membrane and placing a PVDF membrane in its place or overlaying the PVDF membrane on top of the nitrocellulose membrane. The downside of using PVDF membranes in this manner is that they are bigger than the nitrocellulose membranes provided in the stacks and when transferring two gels at a time they do not fit perfectly on the stacks. This is mainly just an aesthetic issue and does not cause problems with protein transfer. Also, the iBlot™ is a dry transfer system and when PVDF membranes are pre-soaked in methanol and water there is sometimes a greenish blue color on the edges of the membranes following transfer. Invitrogen is apparently aware of this problem and it appears to happen when there is excess liquid causing the copper ions to stain the membrane. This usually only happens at the edges between the two membranes and does not appear to affect transfer or detection of proteins. The good news is that iBlot™ stacks containing PVDF membranes should be available by the end of February 2007; hopefully rectifying these issues and allowing you the choice between nitrocellulose stacks or PVDF stacks.