Many experimental operations in biochemistry separate one substance from another. The most commonly used methods are centrifugation, electrophoresis, chromatography, etc., and filtration is an ancient but still commonly used separation technique. In the past ten years, microporous membranes (0.1 ~ 10μm) and ultrafiltration membranes (about 6 ~ 36nm) with different pore diameters have been developed, making filtration technology enter the subcellular level and molecular level, and become molecular biology workers The one used is a simple, but very important technique.
Microporous filters can be used to collect particles of various sizes according to their pore size. In the research of cells and organelles, it is generally called absolute filtration. Many manufacturers supply microporous filters based on the size of the biological sample. In the process of applying the microporous membrane technology, it was found that the cellulose ester microporous membrane also has a special adsorption property. This adsorption property enables the cellulose ester microporous membrane to bind some biopolymers. These biopolymers are actually much smaller than the pore size of the microporous filter membrane. According to the concept of absolute filtration, it is impossible to be trapped on the surface of the microporous filter membrane. Many binding assays have been established based on this adsorption property of cellulose brewed microporous membranes, which have made important contributions to modern biochemical analysis techniques and are widely used in molecular biology.
The application of ePTFE microfiltration membrane filtration technology in biochemistry has the following advantages.
① The method is simple, as long as a suitable microporous filter membrane and a general suction filter device are selected according to the work needs, no other special instrument is required.
② Easy to use and good repeatability. All operations (from collecting samples, separating, washing, drying, and finally identifying and quantifying) are performed on the surface of the same uniform microporous filter membrane, so there is no caused by the transfer of C sample Loss results in low results; nor does it result in high results due to insufficient washing, so repeatability is good.
③Fast, the microporous filter with collected samples can be fully washed quickly. Collecting and washing the pellets by classic centrifugation method is cumbersome and takes a lot of time. In particular, the multi-pipe filter device can filter dozens of samples at the same time. On the other hand, the collection and washing of a single sample can be completed in seconds, which is suitable for studying the kinetics of rapid transfer of small molecules.
As mentioned earlier, mesh-type microporous membranes with various pore sizes are manufactured according to the size of the biological sample. The collected precipitate particles are very small and many are invisible to the naked eye. For example, yeast can be completely collected with a 1.2 μm microporous filter, and E. coli needs to be collected with a 0.45 μm microporous filter. In theory, this type of collection is an absolute collection. Unlike deep-type filter paper, which may miss 1% to 2%, it is often not so absolute and will be affected by many factors. Pay attention to this.