BICINE is an organic compound with molecular formula of C₆H₁₃NO₄ and molecular weight of 163.1717. BICINE is a buffer widely used in biochemical and medical research, such as enzyme reaction buffer, electrophoresis buffer, etc. CN108579472A patent has developed a preparation method of amphoteric ion membrane for biomedical separation. This week, YACOO editor briefly introduced the preparation method of the amphoteric ion membrane. The specific steps are as follows:

1. Preparation of chloromethylation reagent: 15-25g of 1,4-butanediol, 10-20g of formaldehyde and 200-250g of water are mixed and placed in an ice water bath. 60-100g of phosphorus trichloride is added dropwise to keep the temperature at 10-20 ℃. After the reaction, 1,4-dichloromethoxybutane is distilled to obtain chloromethylation reagent;

2. Polyether sulfone chloromethylation：Under the condition of ice water bath at -10 ℃–5 ℃, 20-30g polyethersulfone is completely dissolved in 250-350ml concentrated sulfuric acid. After the temperature is stabilized, 20-35ml of 1,4-dichloromethoxybutane obtained in step 1 is added. The reaction lasts for 20-35min. The solution after reaction is slowly poured into deionized water to obtain white linear polymer chloromethyl polyethersulfone, which is repeatedly cleaned and dried with deionized water;

3.Preparation of membrane casting solution: prepare chloromethyl polyethersulfone, polyethersulfone, diethylene glycol and PEG600 obtained in step 2 into a uniform and transparent membrane casting solution for standby

4. Film scraping: take a clean glass plate and place it horizontally on the film scraping machine. The casting solution obtained in step 3 is streamed onto one end of the glass plate . The 150μm scraper evenly spreads the casting solution on the glass plate, stays for 30-60s, and then immerses it in N-methylpyrrolidone aqueous solution with a mass fraction of 20-30% to cure for 10-30s, and then immerses it in deionized water to cure into a film, and then takes out the film and puts it into clean deionized water for storage;

5. Ionization modification: soak the membrane obtained in step 4 in the aqueous solution of BICINE with a mass fraction of 3% - 5%, place it in a 50-60 ℃ water bath and react for 10-15h, wash it with clean water until it is neutral, and obtain the zwitterionic membrane.

BICINE molecule is a small molecule. When modifying the membrane, there is no problem that the carbon chain molecule is long and the ionic group is far away, resulting in weak electrical properties. In addition, BICINE molecule contains both anion and cation groups, which enhances the hydrophilicity of the membrane and significantly increases the water flux. In addition, the method of using BICINE molecular modification is simple, easy to operate and has strong applicability.

Reference

CN108579472A A preparation method of amphoteric ion membrane for biomedical separation.