Millipore, the multinational bioscience company has announced the availability of a new western blotting technique using the company's Immobilon-P and PSQ transfer membranes. The Double Blotting method was developed by Dr. Françoise Lasne of the National Anti-Doping Laboratory in Chatenay-Malabry, France, to overcome high non-specific binding of secondary antibodies during immunoblotting.

The procedure involves blotting proteins onto a sheet of Immobilon membrane. The membrane is probed with the primary antibody and then assembled with a second membrane sheet. Both membrane sheets undergo a second blotting under acidic conditions. This second blot allows the primary antibody molecules to desorb from their corresponding antigen and transfer onto the second membrane, whereas the antigen and the interfering proteins remain bound to the first membrane. The second membrane can then be probed by secondary antibodies without risk of non-specific binding.

The Double Blotting method is suitable for a wide range of life science research applications. The technique is used currently for the detection of erythropoietin (EPO) in concentrated urine. Compared to traditional practices, Double Blotting minimizes strong non-specific binding of biotinylated secondary antibodies to some urinary proteins.

Millipore's Immobilon-P and PSQ are polyvinylidene fluoride (PVDF) membranes. They have a uniformly controlled pore structure and a high protein binding capacity. In contrast to nitrocellulose materials, Immobilon-P and PSQ membranes demonstrate reliable performance under the acidic conditions needed for Double Blotting.