Electroblotting

Electroblotting is a laboratory technique that transfers macromolecules separated by electrophoresis from a gel onto a solid support, typically a nitrocellulose or polyvinylidene difluoride (PVDF) membrane, under the influence of an electric field. After separation by SDS-PAGE for proteins or agarose electrophoresis for nucleic acids, the molecules migrate out of the gel and bind to the membrane, where they are immobilized for further analysis. This method speeds transfer compared with capillary approaches and generally yields improved transfer uniformity for many samples.

Several formats exist. Wet (tank) transfer uses a buffered system and a pair of electrodes to drive the transfer, while semi-dry transfer uses a thinner chamber and shorter times. Capillary blotting is another historical approach.

Membranes used in electroblotting include nitrocellulose and PVDF; PVDF often requires activation in methanol. The transfer buffer commonly contains Tris-Glycine with methanol or organic modifiers, and the pH and temperature are controlled to optimize efficiency and preserve molecule integrity.

The technique underpins three major blotting families: Southern blotting (DNA), Northern blotting (RNA), and Western blotting (proteins). In Western blotting, immobilized proteins are probed with antibodies for detection; in Southern and Northern blotting, labeled DNA or RNA probes detect complementary sequences.

Advantages include rapid transfer and compatibility with downstream hybridization or antibody-based detection. Limitations include potential loss of very large or very small molecules if transfer parameters are not optimized.

Originating in the late 1970s, electroblotting was developed to improve transfer efficiency and became a standard step in molecular biology workflows such as Western, Southern, and Northern blot analyses.