Unisart® Immunoassays

Line or dot blot strips are still widely used for in vitro diagnostic test, especially for some complex infectious diseases or autoimmune disorders.

The Unisart^® small pore nitrocellulose membranes are well adapted to all protein blotting systems after gel electrophoresis, such as electro transfer, semi-dry or simply capillary blotting. They can be easily cut to the desired gel dimension. Under the electrical field and some capillary drive, proteins move from the gel to the Unisart^® membrane which binds them immediately.

The Unisart^® membranes are also perfectly compatible with line and dot printing. The recombinant proteins can easily be dispensed onto the smooth membrane surface either with contact tips or non-contact nozzles, allowing for sharp lines or spots.

The request for consistency is the important one for IVD strip manufacturers. Only a very consistent nitrocellulose membrane, showing the same characteristics inside a batch and from batch to batch will allow the IVD manufacturer to maintain its production inside the targeted CVs.

The consistency of the final developed signal in a line or blot strip assay is closely dependent on the homogeneity of the membrane surface and structure. Sartorius with its unique know how on membrane production has developed the Unisart 0.22 µm and 0.45 µm nitrocellulose membranes in order to show always the same characteristics inside a lot as well as inter lot.

Key Product Features:

• all sort of Immunoassays with lines or dots can run on a Unisart^® CN membrane
• choice of pore size between 0.22 µm or 0.45 µm
• high protein binding thanks to the dense 3D matrix
• high tensile strength for ease of handling
• application surface always clean and smooth through patented process
• formats: different sheet and roll sizes available
• dispensing: compatible with contact and non-contact equipment
• batch: consistent lots of large amount of rolls available
• certificate guarantees full visual inspection and conformity to specifications
• traceability: labels on boxes , pouches and roll cores

Applications:

The Unisart 0.22 µm and 0.45 µm membranes show an optimum structure for blotting. The small pore size allows for a huge protein binding capacity onto the sponge like 3 dimensional structure. At the same time the high ratio of pores allow for a fast flow through the membrane, as it can be noticed from the electron microscope photo.

The staining of the transferred proteins can easily be done with standard methods like Ponceau S, Coomassie Blue or Amido Black. After transfer, the Unisart nitrocellulose can be processed according to standard protocols.

After incubation with the test sample, the antibody-antigen complex can be revealed on the membrane strip following different methods, including : colorimetric, adding conjugate antibody with alkaline phosphatase or HRP for enzymatic dye detection, but also chemiluminescent and fluorescent with specific labeled molecules or even particles, as also used in lateral flow immunoassays. Due to the production process, the non-supported nitrocellulose membranes like the Unisart 0.22 µm and 0.45 µm, always present two different surfaces, the air and belt side. Each side shall be first evaluated to select the one of choice