Nanofibrous Anion-exchange Membrane For The Efficient Separation Of Nucleic Acid

With the rapid development of the biopharmaceutical industry,the purification and separation technologies of biological macromolecules such as peptides,proteins,enzymes and nucleic acids are increasingly required.The level of technological innovation in the design and development of highly efficient bio-purification materials has become a key factor affecting the high-quality development of modern biopharmaceutical industry.However,the traditional nucleic acid separation and purification technology has many problems,such as low selectivity,high cost and easy to be damaged and contaminated.Nanofiber materials have significant advantages in nucleic acid separation and purification due to their large specific surface area,high porosity and easy to regulate porous structure.In this paper,nanofiber materials and anion exchange technology were combined to design and develop a reusable anion exchange nanofiber crosslinked membrane with low nonspecific adsorption,high nucleic acid adsorption capacity,which provides theoretical and technical support for nanofiber materials in the field of nucleic acid separation.The research content of this paper is mainly divided into the following three parts:Preparation and separation performance of anion-exchange nanofiber two-dimensional membrane:PVA-co-PE nanofibers were stably dispersed in the mixed solvent of isopropyl alcohol and deionized water.Glutaraldehyde and polyethylenimine were used as chemical modifiers,and the primary,secondary and tertiary amines in polyethylenimine were grafted onto the surface of PVA-co-PE nanofibers.The above dispersions were evenly sprayed on the modified PP substrate with excellent hydrophilicity by high-pressure airflow molding technology,and then the two-dimensional anion-exchange nanofiber cross-linked membrane was prepared by drying at room temperature.The effects of morphology,hydrophilicity,pore size distribution,polyethylenimine dosage and gram weight on the RNA adsorption performance of the crosslinked membrane were further analyzed.The results showed that when the mass ratio of glutaraldehyde to polyethylenimine was 12:1:1 and the weight of the crosslinked membrane was 0.85 mg/cm~2,the water contact angle of the membrane was 27.65°,and the adsorption capacity of RNA reached 192.85 mg/g.Moreover,the Kinetics analysis of RNA on the membrane was more suitable for Pseudo second-order Kinetics model.This performance is mainly due to the large number of curved structure of the anion-exchange nanofiber two-dimensional membrane,and the abundant reactive groups on the nanofibers,so the two-dimensional membrane has a good nucleic acid separation performance.Preparation and separation performance of anion-exchange nanofiber three-dimensional membrane:The anion-exchange nanofiber cross-linked membrane with controllable three-dimensional structure was prepared by freeze-drying method after chitosan was fully dissolved in the above dispersions.The structural characteristics and RNA adsorption performance of the three-dimensional anion-exchange nanofiber crosslinked membrane with controllable structure were systematically analyzed,and the adsorption kinetics of the membrane for RNA were also studied.The experimental results show that the maximum adsorption capacity of the cross-linked membrane to the membrane can reach 556.7mg/g when the mass ratio of each component of the three-dimensional composite anion exchange material is 60:2:5:20 according to the nanofiber suspension:chitosan:glutaraldehyde:polyethylenimine and its weight is 1.1mg/cm~2.In addition,the adsorption behavior of RNA on the 3D crosslinked membrane satisfied the Freundlich model,and the Kinetics analysis was suitable for the Pseudo second-order Kinetics model.The n>1 showed that RNA was inclined to be adsorbed from the solution to the surface of the crosslinked membrane,which was an active adsorption process.This performance is mainly derived from the surface functionalized three-dimensional nanofiber network structure,which provides a rich pore structure,high specific surface area and a large number of amine active sites,which can fully capture RNA molecules,and significantly improve the adsorption capacity and capacity of RNA.The influence of p H value on the nucleic acid separation performance of anion-exchange nanofiber membrane:the three-dimensional crosslinked nanofiber membrane material with the maximum adsorption capacity was selected to explore the influence of p H value on the nucleic acid adsorption and separation performance of membrane material.The separation performance of the crosslinked membrane for RNA molecules was systematically studied,including the specific adsorption performance,the concentration and p H of the eluent during the elution process,and the reuse performance.The experimental results showed that when the p H value was 3,the best RNA adsorption performance of the 3D crosslinked membrane was564.3 mg/g.Eluent concentration is 1.5 mol/L,the p H value is 5,elution efficiency as high as98%,and after adsorption elution 5 repetitions,elution efficiency can reach 92%,show that the crosslinked membrane has good ion exchange separation of regeneration performance due to the three-dimensional structure of the crosslinked membrane,which has potential applications on the effective biological separation by ion exchange membrane.