CN114479168A

CN114479168A - Preparation method of alkali-resistant chromatographic membrane and product

Info

Publication number: CN114479168A
Application number: CN202210110242.0A
Authority: CN
Inventors: 钟奇伟; 郑振华
Original assignee: Sepp Hangzhou Filtration Technology Co ltd
Current assignee: Hangzhou Cobetter Filtration Equipment Co Ltd
Priority date: 2022-01-29
Filing date: 2022-01-29
Publication date: 2022-05-13

Abstract

本发明公开了一种层析膜的制备方法，包括如下步骤：(1)具有支化结构的含氮类聚合物与带正电化合物在交联剂存在下制备得到聚合物交联涂层；(2)将所述聚合物交联涂层涂覆于多孔基膜上，后处理得到所述层析膜。本发明通过加入具有一定支化度的聚合物，同时负载正电荷，使得聚合物交联涂层内分子之间形成网状结构，与基材(载体)结合度更高，提高了层析膜的机械强度，捕获效率更高，耐碱性更好。The invention discloses a method for preparing a chromatographic membrane, comprising the following steps: (1) preparing a polymer cross-linked coating from a nitrogen-containing polymer with a branched structure and a positively charged compound in the presence of a cross-linking agent; (2) Coating the polymer cross-linked coating on the porous base membrane, and post-processing to obtain the chromatography membrane. In the present invention, by adding a polymer with a certain degree of branching and loading a positive charge at the same time, a network structure is formed between the molecules in the polymer cross-linked coating, and the bonding degree with the substrate (carrier) is higher, thereby improving the chromatographic membrane. The mechanical strength is higher, the capture efficiency is higher, and the alkali resistance is better.

Description

Preparation method of alkali-resistant chromatographic membrane and product

Technical Field

The invention belongs to the technical field of chromatography, and particularly relates to a preparation method of an alkali-resistant chromatographic membrane and a product.

Background

Chromatographic membranes are mainly used for removing large negatively charged impurities, such as endotoxin, viruses, nucleic acids, Host Cell Proteins (HCPs) and the like, by adsorption of positive ions present on the membrane. The existing preparation process generally utilizes a hydrophilic porous membrane (such as PES) to be crosslinked with a polymer with positive charges, and then the hydrophilic porous membrane is solidified to obtain a chromatographic membrane with positive charges.

Patent document CN101474552A discloses a porous sorption medium comprising a substrate having a first outer side and a second outer side, both sides being porous with a thickness of porosity in between, said substrate being hydrophilic and having a sorption material substantially covering said substrate solid matrix and said first and second outer surfaces, said sorption material comprising a cross-linked polymer having quaternary ammonium ion functional groups connected by non-polar linking groups, wherein said substrate comprises a microporous membrane and said cross-linked polymer is modified with a charge modifier comprising an organic compound having quaternary ammonium ion groups connected through said non-polar linking groups to moieties capable of reacting with said cross-linked polymer.

The existing chromatographic membrane does not relate to alkali resistance evaluation, and the pH value of the chromatographic membrane product in the market is limited during elution, and the maximum pH value is 0.5M NaOH.

Disclosure of Invention

The invention provides an alkali-resistant chromatographic membrane with high branching degree, which has wider use environment and can withstand more severe application environment.

A preparation method of a chromatographic membrane comprises the following steps:

(1) preparing a polymer cross-linked coating from a nitrogen-containing polymer with a certain branching degree and a positively charged compound in the presence of a cross-linking agent;

(2) and (3) coating (coating or dipping or spin coating) the polymer cross-linked coating on a porous base membrane, and carrying out post-treatment to obtain the chromatographic membrane.

Preferably, the porous base membrane is a microfiltration membrane, and a hydrophilic porous base membrane can be selected. The hydrophilic porous base membrane includes, but is not limited to, porous hydrophilic membranes such as hydrophilic polyethersulfone membrane, hydrophilic polytetrafluoroethylene membrane and cellulose acetate membrane, preferably hydrophilic polyethersulfone membrane. These membrane materials can be prepared by conventional methods, or commercially available products can be used. The pore diameter is generally 0.1 to 20 μm, more preferably 0.45 to 3 μm.

Preferably, the nitrogen-containing polymer has a branching degree of 10% by weight or more. More preferably, the degree of branching is 20% or more. More preferably, the nitrogen-containing polymer has a branching degree of 20 to 95%; more preferably, the nitrogen-containing polymer has a branching degree of 30 to 95%.

Preferably, the nitrogen-containing polymer is selected from one or more of Polyacrylamide (PAM), Polyetheramine (PEA), polyoxyethylene diamine, polyoxyethylene amine, Polyethyleneimine (PEI), polyallylamine-hydrochloric acid. More preferably, the nitrogen-containing polymer is selected from the group consisting of polyacrylamide and polyethyleneimine. More preferably, the nitrogen-containing polymer is selected from polyacrylamide and polyethyleneimine. The molecular weight of the polyacrylamide is 300-2000 w; more preferably 500w to 1500 w; the molecular weight of the polyethyleneimine is 500-100 ten thousand; more preferably 500 to 80 ten thousand.

In the present invention, the nitrogen-containing polymer may be a commercially available product or may be prepared by itself.

Preferably, the positively charged compound is selected from one or more of epoxy quaternary ammonium (2, 3-epoxypropyltrimethylammonium chloride (glycidyltrimethylammonium chloride), (3-chloro-2-hydroxypropyl) trimethylammonium chloride, (2-aminoethyl) trimethylammonium chloride (hydrochloride)), halogen quaternary ammonium ((2-chloroethyl) trimethylammonium chloride) and aldehyde quaternary ammonium (formylmethyltrimethylammonium chloride).

In the step (1), under the action of a coupling agent, nitrogen in the nitrogen-containing polymer and a positively charged compound are subjected to a grafting reaction (epoxy group ring opening, halohydrocarbon coupling and aldehyde group Schiff base reaction).

Preferably, the crosslinking agent is selected from epichlorohydrin or other polyfunctional epoxy compounds (epichlorohydrin), various bromine chemicals or other polyfunctional halides; formaldehyde and other polyfunctional aldehydes (glutaraldehyde, etc.), bis (2-hydroxyethyl) sulfone, dimethyldichlorosilane, dimethylol urea, dimethylol ethylene urea, diisocyanate esters or polyisocyanates.

Preferably, the reaction conditions of step (1) are: the reaction temperature is 25-90 ℃ and the reaction time is 0.5-10 hours.

After the reaction in the step (1) is finished, the polymer cross-linked coating solution is directly obtained without additional treatment.

After the coating, dipping or spin coating is finished, waiting for 0.5-30min, removing the redundant polymer cross-linked coating, and putting the coating under a UV lamp for ultraviolet irradiation for 2-5h for full reaction; after finishing, the membrane is put into a water bath with the temperature of 30-100 ℃ for cleaning for 10-150min, and is put into an oven with the temperature of 40-80 ℃ for drying until the weight is constant.

Preferably, the nitrogen-containing polymer, the positively charged compound and the crosslinking agent account for the following components in percentage by mass, respectively, based on the total weight of 100: 1-30%, 3-20%, 0.1-5%; the balance of water. More preferably, the nitrogen-containing polymer, the positively charged compound and the crosslinking agent are, in mass percentage, based on the total weight of 100: 2-15%, 5-15%, 0.5-3%; the balance of water.

More preferably, the nitrogen-containing polymer, the positively charged compound and the crosslinking agent are, in mass percent, based on the total weight of 100, respectively: 2-10%, 5-8%, 0.5-2%; the balance of water.

Preferably, in the step (1), the nitrogen-based polymer with a certain branching degree and the positively charged compound are added into water, then the mixed solution is placed in a water bath kettle at the temperature of 25-90 ℃ to be heated for 0.5-10 hours, the mixed solution is cooled to room temperature after the reaction is finished, and then the added cross-linking agent is stirred at room temperature for 5-40 min to obtain the polymer cross-linking coating material liquid.

Before reaction, the mixed solution comprises the following components in percentage by weight: nitrogen-based polymer of degree of branching: 1-30%; 1-20% of positively charged compound; the remainder being water. Preferably, the weight percentage of the mixed solution is as follows: nitrogen-based polymer of branching degree: 2-15%; 5-15% of positively charged compounds; the remainder being water.

The addition amount of the cross-linking agent is 0.1-5% of the total material amount; more preferably 0.5 to 2%.

The invention also provides a chromatographic membrane prepared by the preparation method of the chromatographic membrane in any technical scheme.

The dynamic BSA loading capacity of the chromatographic membrane prepared by the invention is between 30 and 80 (mg/mL). In practice, the amount of the dynamic BSA carried may be controlled by controlling the type of the nitrogen-containing polymer, the molecular weight of the nitrogen-containing polymer, the branching degree of the nitrogen-containing polymer, the total amount of the positively charged compounds, and the like, as required, so as to obtain a chromatographic carrier having the desired performance.

Compared with the prior art, the invention has the beneficial effects that:

according to the invention, through adding the polymer with a certain branching degree and simultaneously loading positive charges, a network structure is formed between molecules in the polymer cross-linked coating, the binding degree with a base material (carrier) is higher, the mechanical strength of the chromatographic membrane is improved, the capture efficiency is higher, and the alkali resistance is better.

Detailed Description

Example 1

The total material amount is 250g, polyacrylamide (PAM with the molecular weight of 500w and the addition amount of 25g) with the branching degree of 60 percent accounting for 10 percent of the total material weight and formylmethyltrimethylammonium chloride accounting for 10 percent of the total material weight are added into deionized water with the weight of 79.5 percent, then the mixed solution is placed into a water bath with the temperature of 30 ℃ for heating for 10 hours, after the reaction is finished, the mixed solution is cooled to the room temperature, 0.5 percent of glutaraldehyde is added, and the mixture is stirred for 30 minutes at the room temperature, so that the polymer cross-linked coating material liquid is obtained. Immersing a hydrophilic PES membrane (with the average pore diameter of 0.45-3 mu m, obtained by a conventional method, such as being prepared by a method with the publication number of CN 104258745A (hydrophilic nano particles and a surfactant are not required to be added during preparation)) into a polymer cross-linked coating feed liquid by an immersion method, removing the redundant feed liquid on the surface of the PES membrane, irradiating and reacting for 3 hours by using a UV lamp, finally cleaning for 30min in water bath at 30 ℃, and drying at 40 ℃ to obtain the hyperbranched chromatographic membrane. The loading of BSA tested was 50 mg/mL.

BSA loading detection was as follows (ref: He D, Ulbricht M.preparation and characterization of probability of change Membrane absorbers with high protein-binding capacity [ J ]. Journal of Membrane Science,2008,315(1-2): 155-163.):

in the actual detection, BSA protein solution with a certain concentration is passed through

The disposable filter on the Pure system is contacted with the target material (chromatographic membrane to be tested) at a determined flow rate of 10 membrane volumes per minute (mV/min) until the concentration after the filter outlet exceeds 10% of the loading concentration. Protein concentration is linearly related to UV absorbance, and concentration changes can be detected by UV detection probes in the system, which are well known to those skilled in the art. The total amount of protein adsorbed onto the filter at 10% breakthrough was determined by analyzing the chromatograms in the Unicorn software, taking into account the dead volume in the system and reservoir equipment.

Calculation method of the degree of branching DB:

d, T, L in the formula respectively represents the proportion of atomic mass in dendritic structure, terminal position structure and linear structure in the hyperbranched polymer molecule. Where the linear structure is selected as the chain segment with the largest number of main chain atoms, the value of which can be measured by NMR and DB of 100 for a fully branched polymer molecule.

Examples 2 to 37

Experiments were performed according to the method of example 1 with reference to the materials and material ratios in tables 1, 2 and 3, and the results of BSA loading measurements are shown in tables 1, 2 and 3:

TABLE 1

TABLE 2

TABLE 3

As can be seen from tables 1 and 2: when the molecular weight is unchanged, the dynamic loading increases with the increase of the branching degree; when the degree of branching is the same, the dynamic loading increases with increasing polymer molecular weight, and it is possible that, at the same degree of branching, higher molecular weight polymers can provide more active sites, thereby increasing the loading; it can be known from table 3 that the different quaternary ammonium active groups have equivalent dynamic protein loading after the polyacrylamide with the same branching degree is quaternized, which indicates that the quaternary ammonium groups with different active groups can perform quaternization with the nitrogen-containing polymer, and have excellent protein capture capability.

Alkali resistance evaluation:

(1) alkali resistance test at different concentrations:

the method comprises the following specific operation steps: the chromatographic membrane prepared in example 3 was immersed in an alkaline solution (aqueous sodium hydroxide solution) having a concentration shown in table 3 for 12 hours, and the BSA loading was measured, and the measurement results are shown in table 4 below:

table 4: soaking for 12h, and then polyacrylamide

Alkali concentration (mol/L)	0.1	0.5	1
				BSA loading (m)g/mL)	43	43	43

From the alkali resistance results, the chromatographic membrane obtained by the method has good alkali resistance, and has good BSA (bovine serum albumin) loading capacity within the range of 0.1-1 mol/L of reduced concentration.

(2) Alkali resistance test for different elution times:

the method comprises the following specific operation steps: the chromatographic membrane prepared in example 16 was immersed in a 1mol/L aqueous NaOH solution (aqueous sodium hydroxide solution) for 0.5, 1, 3, 7, and 14 hours, and the BSA loading was measured, the results of which are shown in table 5 below:

table 5: alkali concentration 1M NaOH

Time (d)	0.5	1	3	7	14
						BSA loading (mg/mL)	62.0	60.3	61.2	58.9	46.6

From the alkali resistance detection results, the chromatographic membrane obtained by the method can still maintain higher BSA (bovine serum albumin) loading capacity after long-time alkali washing, and further proves that the chromatographic membrane has better alkali resistance.

(3) Test of different chromatographic membranes for alkali resistance

The method comprises the following specific operation steps: the prepared chromatographic membrane is placed in a 1mol/L sodium hydroxide aqueous solution, soaked for 12 hours, and the BSA loading is detected, wherein the detection results are shown in the following table 6:

table 6: soaking in 1mol/L sodium hydroxide water solution for 12h

The detection results in Table 6 show that the alkali resistance of the modified chromatographic membrane is greatly reduced by selecting the polymer with lower branching degree, and the rest of the hyperbranched modified chromatographic membranes have better alkali resistance, thereby greatly expanding the application field of the chromatographic membrane.

Claims

1. a preparation method of chromatographic membrane, is characterized in that, comprises the steps:

(1) preparing a polymer cross-linked coating with a nitrogen-containing polymer having a branched structure and a positively charged compound in the presence of a cross-linking agent;

(2) Coating the polymer cross-linked coating on the porous base membrane, and post-processing to obtain the chromatography membrane.

2 . The method for preparing a chromatography membrane according to claim 1 , wherein the porous base membrane is a hydrophilic porous base membrane. 3 .

3. The preparation method of chromatography membrane according to claim 2, wherein the hydrophilic porous base membrane is selected from the group consisting of hydrophilic polyethersulfone membrane, hydrophilic polytetrafluoroethylene membrane, cellulose acetate membrane.

4. The preparation method of chromatographic membrane according to claim 1, is characterized in that, described nitrogen-containing polymer is selected from polyethyleneimine, polyacrylamide, polyetheramine, polyoxyethylene diamine, polyoxyethylene One or more of vinylamine, poly(allylamine), and poly(allylamine·hydrochloric acid), and the degree of branching is 20% or more.

5. the preparation method of chromatographic membrane according to claim 1 is characterized in that, described positively charged compound is selected from epoxy quaternary ammonium salt, one in halogen quaternary ammonium salt and aldehyde group quaternary ammonium salt one or more.

6. the preparation method of chromatographic membrane according to claim 1 is characterized in that, described cross-linking agent is selected from epichlorohydrin, epichlorohydrin, formaldehyde, two (2-hydroxyethyl) sulfone, dimethyl dichlorosilane, dimethylolurea, dimethylolethyleneurea, diisocyanate or polyisocyanate.

7 . The method for preparing a chromatography membrane according to claim 1 , wherein the reaction conditions of step (1) are: the reaction temperature is 25-90° C., and the reaction time is 0.5-10 hours. 8 .

8. the preparation method of chromatographic film according to claim 1, is characterized in that, after step (2) completes described coating, waits 0.5-30min, puts into UV lamp under ultraviolet irradiation 2-5h and fully reacts; End Afterwards, put the membrane in a water bath at 30-100°C for 10-150min, place it in an oven at 40-80°C, and dry to constant weight.

9. The preparation method of chromatographic membrane according to claim 1, is characterized in that, taking the total weight as 100, the mass percentages of the nitrogen-containing polymer, the positively charged compound and the cross-linking agent are respectively : 1 to 30%, 3 to 20%, 0.1 to 5%.

10 . A chromatographic membrane, characterized in that, it is prepared by the method for preparing a chromatographic membrane according to any one of claims 1 to 9 .