Difference Between PVDF Filter Membrane and Nitrocellulose Membrane
Filter membrane is used for the separation and concentration of solutes in the treatment solution and is also commonly used for the separation of colloidal suspensions. It can be made of different materials with different properties. Today, HAWACH will talk about the difference between PVDF and nitrocellulose filter membrane.
PVDF is the abbreviation of Polyvinylidene Fluoride, which is made by coating the surface of PVC film with PVDF resin. Its performance is better than pure PVC membrane material, and the price is correspondingly slightly higher than pure PVC membrane material. Compared with ordinary PVC membranes, PVDF membrane has improved durability to about 7~10 years.
Compared with the nitrocellulose membrane, the PVDF membrane filter has superior performance in protein retention, mechanical strength, and chemical compatibility. The typical binding capacity of commercially available nitrocellulose membrane is 80-100μg/cm2, while the binding capacity of PVDF membrane is 100-200μg/cm2 (and the binding strength of PVDF is 6 times stronger than nitrocellulose membrane).
But the advantages of PVDF membrane are not only here: better mechanical strength and chemical resistance make PVDF membrane an ideal choice for various staining applications and multiple immunoassays, and the lane copy of a single gel can be used for multiple purposes In particular, N-terminal protein sequencing is required. Under very “rigorous” cleaning conditions, PVDF membranes still maintain their original colors when nylon or nitrocellulose membranes have degraded. So PVDF membrane is the best choice for protein sequencing. But it is not suitable for fluorescence.
The special attention to PVDF membrane is that it needs to be pretreated with 100% methanol (no more than 15 seconds) and then equilibrated with buffer solution before it can be used, and if it dries during the application process, it must be processed in the same procedure.
PVDF membrane is also divided into 0.45um and 0.2um. The latter has a small pore size and has better interception and adsorption of small molecule proteins, and the background may be slightly higher than the former.
Nitrocellulose membrane is a widely used transfer medium for western blotting. It has a strong binding ability to proteins and is suitable for various color development methods, including isotope, chemiluminescence (Luminol), conventional color development, dyeing and fluorescent color development, low background, and high signal-to-noise ratio.
The use of the NC membrane is also very simple. For example, no formaldehyde pretreatment is required. Just soak the air bubbles on the non-ionized water surface and equilibrate in electrophoresis buffer for a few minutes. For example, the NC membrane is easy to seal, and no special cleaning conditions are required.
The protein transferred to the NC membrane can be stored stably for a long time under suitable conditions, but it should be noted that the pure nitrocellulose membrane is relatively fragile and easy to roll. Be careful in handling and not suitable for repeated cleaning.
When choosing a nitrocellulose membrane, the operator should pay attention to choosing a suitable pore size. Generally, a 0.45um pore size membrane is used for macromolecular proteins above 20KD. If it is less than 20KD, it is recommended to choose 0.2um. If it is less than 7KD, it is better to choose a 0.1um membrane. In addition, pay attention to choosing pure NC membrane-the binding force of NC membrane mixed with cellulose acetate (CM) will be reduced.
In addition, since the protein-bound on the NC membrane will be replaced by some detergents, it is better to use a milder one when sealing, and the concentration should not exceed 0.3% (it is said that 0.05% is effective).
Generally speaking, the purer the NC membrane, the higher its protein binding capacity, so to increase the sensitivity and resolution of WB and improve the purity of the membrane used is a choice that can be considered. If the NC membrane is mixed with some acetylated cellulose, which has been mentioned earlier, it will affect protein binding.