Cellulose nitrate membrane filters are indicated for many general laboratory applications where a membrane with a high non-specific adsorption is suitable. They are hydrophilic, have high flow rates thanks to their symmetric structure and are compatible with aqueous solutions(pH 4 to 8), hydrocarbons and several other organic solvents.
The cellulose nitrate membranes are available in different pore sizes from 0.2 μm to 8 μm.
Cellulose acetate membranes combine high flow rates and thermal stability with very low adsorption characteristics, and are therefore excellently suited for use in pressure filtration devices. They are hydrophilic, have high flow rates thanks to their symmetric structure and are compatible with aqueous solutions(pH 4-8), oils, alcohols and other organic solvents. The 0.2 μm membrane is the filter of choice for sterile filtration of aqueous solutions, such as nutrient media, buffers and sera.
The cellulose acetate membranes are vailable in different pore sizes from 0.2 to 5 μm.
The very low adsorption membranes are hydrophilic, solvent-resistant (pH 3-12) and therefore suited for the particle removal from solvents. The membrane is asymmetric and reinforced with nonwoven cellulose.
They are available in two pore sizes: 0.45 μm and 0.2 μm.
Polyethersulfone (PES) membrane filters are hydrophilic, have high flow rates, a low non-specific protein adsorption and are chemically resistant over a pH range of 1 – 14. They are therefore recommended for the filtration of aqueous solutions as well for protein filtration. Furthermore, the low level of extractables makes them suitable for environmental analysis.
Those white and hydrophilic polycarbonate track-etched membranes are manufactured from high grade polycarbonate film usingtrack-etch technology. Their capillary pore structure is uniform and precise, with a narrow pore size distribution to retain particles on their surface. Track-etched membranes are an excellent choice for accurate fractionation of particulates because of their precise pore size.
Track-etch technology offers the user distinct performance advantages when excellent surface capture and high sample visibility are required. Their main applications are particulate analysis, epifluorescence microscopy, fluid clarification, cytology, cell biology, bioassays, water microbiology and environmental analysis.
Polyamide membrane filters are hydrophilic and chemically resistant to alkaline solutions and organic solvents. They are therefore recommended for the particle removal from aqueous solutions and solvents for analytical determination such as HPLC, for the sterile filtration of these liquids as well as for applications where a membrane with a relatively high nonspecific adsorption is suitable.
The main application of these membrane filters is the filtration of air, gases or chemicals. They are made of PTFE (polytetra-fluorethylene) only and are therefore permanently hydrophobic. Unlike other (hydrophilic) filter types, they are not wetted by air humidity, allowing unhindered passage of air at lowdifferential pressures as well. PTFE membrane filters have an excellent chemical compatibility (pH 1 to 14), so that they are also used for the filtration of solvents and acids, to which other filter types are not resistant. Due to their hydrophobic characteristics, they must be pre-wetted with ethanol or methanol before the filtration of aqueous media.
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.
Sartorius nitrocellulose membranes are available in two pore sizes, 0.22 μm and 0.45 μm. Both versions combine the advantages of high protein binding capacity with low background and high membrane stability, which ensures easy handling. Due to its large surface area, the 0.22 μm membrane version is recommended for small proteins. Sartorius blotting membranes are ideal for western blotting, DNA blotting as well as dot or slot blots. They have been optimized for all protein blotting systems, such as electrotransfer, semi-dry or simple capillary blotting.