Being a research scientist dealing with protein extraction, you have a better idea of how important it is to get high protein yield. Forget the old methods of protein purification with a negligible amount of product. Now you can get maximum yield of protein from a small fraction of sample tissue with cellulose acetate membrane.
What Is Cellulose Acetate Membrane?
Cellulose acetate membrane is made from a polymer of cellulose diacetate, however it may also contain polymer adhesive. Loeb and Sourirajan synthesized the membrane for the first time in 1950. The cellulose acetate membrane available these days is manufactured from a mixture of cellulose acetate and triacetate. The acetone-based solution of cellulose acetate polymer is cast on a thin film of polyester fabric. Coldwater bath, followed by high annealing temperature, completes the casting process of the membrane.
Acetone is evaporated to remove the solvent. The immersion of membrane in cold water is an additional step in removing the solution. The temperature ranges for the high-temperature annealing of the membrane is 60-90oC. The annealing temperature step improves the semi-permeability feature of the membrane as a result of high-temperature annealing osmosis increases, and salt transport decreases.
The processing of membrane produces an asymmetric structure with a density of surface layer about 1000-2000 A. The high density imparts salt rejection property to the cellulose membrane. The spongy part of the membrane allows water to move freely. The feature of the membrane to allow water flux and salt rejection is adjusted during the annealing step.
Uses Of Cellulose Acetate Membrane
Some of the applications of cellulose acetate membrane are:
- The membrane effectively filters salts from a solution. The membrane does not allow the salt to pass through it.
- The membrane doesn’t bind organic molecules. Which means they are an excellent source to filter organic compounds like proteins and enzymes. The hydrophilic nature does not allow them to bind protein.
- In experiments where protein purification is obtained by binding the proteins to membrane-bound particles. This property finds its use in food analysis and environmental monitoring.
- The transparency of these membrane finds their use as photographic film. But due to fragile nature, they cannot withstand high temperatures. Exposure to high temperature degrades the film, so their use is limited to ultrafiltration in lab-scale experiments.
- In the water filtration system, it removes unwanted salts and substances from water.
- Membrane with pore size 0.22µ and 0.45µ are used in pharmaceutical processes.
Why Prefer Cellulose Acetate other membranes?
Cellulose acetate is a hydrophilic membrane with a very less or negligible affinity to bind protein molecules. This feature makes it suitable to purify the protein from a tiny sample size effectively. Apart from that, the membrane withstands higher temperatures effectively up to 180oC. These membranes are biodegradable, so they do not pollute the environment.
Several companies are manufacturing the membrane with the improvement of the basic features, i.e., pore size, permeability, hydrophilic nature. Some of the leading manufacturers with worldwide customers are:
Thermo-Scientific Fisher: Apart from manufacturing cellulose acetate membrane, they also synthesize the surfactant-free cellulose acetate membrane. Due to the absence of a surfactant or wetting agent, the membrane is effective for downstream cleanliness like low protein binding of cell culture.
Whatman: The membrane is synthesized from pure cellulose acetate, making it suitable for lab-scale purification experiments and scintillation measurements. Whatman cellulose acetate membrane filters are really good to consume.
SterliTech: The hydrophilic nature of the membrane effectively filters salts and pollutants from water. It works for a longer duration, reduces filtration cost.