PVDF polyvinylidene fluoride, molecular formula: -(C2H2F2) N -, mainly refers to vinylidene fluoride homopolymer or vinylidene fluoride and other small amount of fluorinated vinyl monomer copolymer, it has both fluorine resin and general resin characteristics, in addition to good chemical resistance, high temperature resistance, oxidation resistance, weather resistance (can be used outdoors for a long time), radiation resistance, Also has piezoelectric properties, dielectric properties, thermoelectric properties and other special properties, chemical structure with a fluorocarbon bond, the structure with short bond properties and hydrogen ions form the most stable and solid combination. PVDF has poor hydrophilicity.
Therefore, as long as the PVDF membrane is treated with methanol for 30 seconds or so, the PVDF membrane can be completely transformed from hydrophobic state to hydrophilic, and the effect is the same after the extension of time. At the same time, observe with naked eyes whether there are white spot-like or blocky areas on the membrane surface, and then soak the membrane into the TransferBuffer for 15min. The PVDF membrane used was soaked in methanol for 1-2min. The membrane instruction manual of a company says that it is soaked in methanol for 1-2min.
PVDF membrane can bind proteins and separate small fragments of proteins. It was initially used for protein sequencing. Since nitrocellulose membrane would degrade in Edman reagent, PVDF was sought as a substitute, although the efficiency of PVDF membrane binding proteins was not as high as nitrocellulose membrane. But its stability and corrosion resistance make it ideal for protein sequencing, and it remains in use today. PVDF membrane and nitrocellulose membrane, can be a variety of staining and chemiluminescence detection, but also has a wide range of application. This PVDF membrane has higher sensitivity, resolution and protein affinity than conventional membranes under fine craftsmanship, making it ideal for the detection of low molecular weight proteins.
However, before using PVDF membrane, it must be pretreated with anhydrous methanol, and then balanced in the transferBuffer before it can be used (the purpose of methanol bubble in PVDF membrane is to activate the positive group on PVDF membrane, so that it is easier to combine with negatively charged proteins). The transferbuffer without methanol can be used in the transfer of the pretreated PVDF membrane.
SDS increases the water solubility of protein and promotes the protein to swim in the electrolysis solution. If no SDS is added, protein will precipitate on the glue, but too much SDS will affect the adsorption of protein and membrane.
Methanol can separate SDS from protein, and the higher the concentration of methanol, the faster the separation of SDS from protein, but the high concentration of methanol will have a fixed effect on protein, which is not conducive to the protein running out of the glue. Generally speaking, the concentration of methanol is 20%, but the ability of PVDF membrane to intercept the small molecule pigments handed in by marker is poor, so it can be considered to increase the concentration of methanol to 25% (it has little influence on the membrane transfer of common proteins, and pigment interception is more). Large protein transfer can be considered to reduce methanol concentration, in addition SDS must be added. Another function of methanol is to cool down. Due to the consumption of electrolyte and volatilization of methanol, the current or voltage changes faster and the temperature rises faster in the old electroconversion liquid during electroconversion, so additional methanol can be considered. This is of great significance to the semi-dry transfer buffer, because the consumption of semi-dry transfer buffer is very slow, the buffer is placed for a long time, and the methanol volatilization is more serious, which can be temporarily supplemented in a small amount.
Post time: Jun-27-2022