Cytiva, 10402578, Whatman™ Protran™ BA83 nitrocellulose membrane, 25 mm, circle (1000/Pk)

For flow-through and Western blotting, Southern blotting and Northern blotting assays, small-pore unsupported membranes are ideal as they are highly sensitive with large surface area and high protein binding capacity. Choosing a membrane with a small pore size avoids the small protein migrating too deeply into the membrane surface before binding into the nitrocellulose which causes a loss of signal or sensitivity. Flow-through immunoassays offer a lower degree of integration than lateral-flow immunoassays which makes development and production easier. It may also be easier to develop multi-analyte tests because the spatial position of a capture molecule on the membrane is not linked to the assay dynamics as in a lateral flow assay. Line blot assays are an easy to develop, lab-based assay that can be multiplexed to support limited sample volumes. Confirmatory blots are usually Western blots (e.g., chasing anti-HIV antibodies in patient sera). Southern blot analysis is especially useful for analysis of repetitive sequences because multiple similar sequences in the genome can be analyzed by a single probe.