A method for preparing a three-dimensional thermoplastic polymer nanofiber aerogel for protein adsorption separation and an article thereof

Abstract

The application specifically relates to a preparation method of a three-dimensional thermoplastic polymer nanofiber aerogel for protein adsorption separation. The method comprises the following steps: first, preparing thermoplastic nanofiber by melt blending phase separation of thermoplastic polymer and cellulose acetate butyrate; second, dispersing the thermoplastic nanofiber and a crosslinking agent in a solvent to form a suspension; third, freeze-drying the suspension to form uncrosslinked thermoplastic polymer nanofiber aerogel; fourth, performing crosslinking stabilization treatment on the uncrosslinked aerogel, and cleaning and freeze-drying to obtain three-dimensional thermoplastic polymer nanofiber aerogel material with fixed fiber crosspoint bonding; and fifth, completely immersing the three-dimensional thermoplastic polymer nanofiber aerogel in a protein modification liquid for 30-60 min, performing thermal grafting treatment after freeze-drying, and cleaning to obtain the three-dimensional thermoplastic polymer nanofiber aerogel for protein adsorption separation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of nanofiber aerogels for adsorption separation, and particularly relates to a three-dimensional thermoplastic polymer nanofiber aerogel for protein adsorption separation and a preparation method thereof. BACKGROUND

[0002] Proteins are an important functional macromolecule in living organisms, and have wide applications in the fields of biological medicine, food engineering, daily chemical industry, health care, etc. In order to ensure the safety and biological activity of protein products, there is a very high requirement for the purity of proteins, even reaching the reagent or pharmacopoeia standard. Adsorption separation method is mainly based on a chromatographic column composed of adsorption medium to realize the separation and purification of target substances, and has the characteristics of large processing capacity, wide applicability, convenient operation, continuous production, good selective adsorption, excellent cyclic adsorption effect, etc., and is the most widely used industrialized protein separation and purification method at present.

[0003] Thermoplastic polymer nanofiber aerogels have good chemical stability, mechanical strength, multifunctionality and continuity, and their large specific surface area provides a stable and extensive solid matrix for in-situ graft polymerization of adsorption functional groups, thereby obtaining an adsorption separation material with good performance. In recent years, thermoplastic polymer nanofiber aerogels have been widely used as base materials of adsorption medium, and can be used to construct a three-dimensional aerogel material with stable structure without adding too many organic additives. This material combines the adsorption performance of functional groups and the unique performance of thermoplastic polymer nanofiber aerogels, and has the characteristics of small density (1-500 mg / cm 3 ), low cost (about 0.0105 yuan / cm 3 ), and controllable morphology and size, and compared with traditional adsorption medium micro-nanoparticles (density of 15-1500 mg / cm 3 , cost of about 0.3-0.8 yuan / cm 3 ), can meet different needs in the actual application of protein adsorption.

[0004] The existing related literature (Shapeable, underwater superelastic, and highly phosphorylated nanofibrous aerogels for large-capacity and high-throughput protein separation [J]. ACS Applied Materials & Interfaces, 2019, 11 (47): 44874-44885.) prepares shape-controllable composite nanofiber aerogels by freeze-drying and heat curing method, but the modification reagents such as various binders and cross-linking agents need to be added in the aerogel construction forming process, which is not conducive to the construction of low-cost and simple operation protein adsorption medium. The domestic patent CN202211155645.3 discloses a preparation method of aramid assisted polyvinyl alcohol aerogel, which needs to prepare a precursor, perform sol-gel transformation, solvent replacement and drying treatment to obtain the aerogel. Multiple steps are required, and the process is complicated. Therefore, there is an urgent need to invent a gel protein adsorption and separation material with small pollution, large processing capacity and higher efficiency of fiber making. SUMMARY

[0005] In order to solve the problems in the prior art, the present application provides a three-dimensional thermoplastic polymer nanofiber aerogel for protein adsorption and separation and a preparation method thereof, which does not need to go through the complicated precursor preparation and sol-gel transformation and solvent replacement process, improves the work efficiency, simplifies the preparation method and reduces the addition of chemical reagents.

[0006] In one aspect, the present application provides a preparation method of a three-dimensional thermoplastic polymer nanofiber aerogel for protein adsorption and separation, and the specific steps are as follows:

[0007] First step: thermoplastic polymer and cellulose acetate butyrate are prepared into thermoplastic nanofibers by melt blending phase separation method;

[0008] Second step: disperse the thermoplastic nanofiber and the cross-linking agent in the solvent to form a suspension;

[0009] Third step: freeze-dry the suspension to form an uncrosslinked thermoplastic polymer nanofiber aerogel;

[0010] Fourth step: crosslinking and stabilization treatment is performed on the uncrosslinked aerogel, and the three-dimensional thermoplastic polymer nanofiber aerogel material with fixed fiber crosslinking points is obtained after washing and freeze-drying;

[0011] Step 5: The three-dimensional thermoplastic polymer nanofiber aerogel is completely immersed in a protein modification solution for 30-60 min, and after freeze-drying, heat grafting treatment is performed, and after washing, a three-dimensional thermoplastic polymer nanofiber aerogel for protein adsorption and separation is obtained.

[0012] Further, the mass ratio of the thermoplastic polymer to cellulose acetate butyrate in the first step is 1:1.5-39, and the thermoplastic polymer is any one or a combination of polyolefin-vinyl alcohol copolymer, polyolefin-acrylic acid copolymer, polyolefin-methacrylic acid copolymer, maleic anhydride grafted polyolefin, and polyamide.

[0013] Further, the conditions of the phase separation method in the first step include a temperature of 220-250°C, a stretching air speed of 300-600 m / s, and ring blowing air cooling.

[0014] Further, the mass fraction of the thermoplastic nanofiber in the suspension in the second step is 0.01-50%, the average diameter of the thermoplastic nanofiber is 50-300 nm, and the average length-diameter ratio of the fiber is 5-50,000; and the solvent is any one or a combination of water, methanol, ethanol, propanol, isopropanol, tert-butanol, acetone, acetic acid, sulfuric acid, and hydrochloric acid.

[0015] Further, the crosslinking agent in the second step is any one or a combination of glutaraldehyde, glyceraldehyde, borax, diisocyanate, and polyamide-epichlorohydrin resin.

[0016] Further, the freeze-drying process in the third step, the fourth step, and the fifth step is precooling and drying, wherein the precooling is freezing in a -80°C freezer for 12-48 h, and the drying is drying in a -40°C cold trap with a pressure of 0.1-1.0 Pa for 48-72 h.

[0017] Further, the crosslinking and stabilization treatment in the fourth step is any one or a combination of heat crosslinking, ultrasonic crosslinking, microwave irradiation crosslinking, infrared irradiation crosslinking, ultraviolet irradiation crosslinking, and plasma irradiation crosslinking.

[0018] Further, the modification solution in the fifth step is a mixed solution prepared by mixing a modifier, a catalyst, and a solvent; the modifier is any one of butane tetracarboxylic acid, citric acid, sodium alginate, pyromellitic dianhydride, and 3-carboxybenzenesulfonic acid sodium; the catalyst is polyphosphoric acid or sodium hypophosphite; and the solvent is any one or a combination of water, acetone, tetrahydrofuran, n-hexane, toluene, DMSO, and N,N-dimethylformamide.

[0019] The second aspect of the present application also provides a preparation method of a three-dimensional thermoplastic polymer nanofiber aerogel for protein adsorption separation.

[0020] Further, the three-dimensional thermoplastic polymer nanofiber aerogel for protein adsorption separation has the following properties: a bulk density of 1-500 mg / cm 3 , an average pore size of 0.1-200 μm, and a specific surface area of 20-2000 m 2 / g; the fibers are interpenetrated and staggered to form a connected pore structure.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] 1) The present application can prepare thermoplastic nanofibers in large quantities, efficiently and at low cost by melt blending extrusion phase separation method, which is more efficient and greener than the method of preparing fibers such as electrospinning. In the construction process of the existing aerogel protein adsorption material, various binders, dispersants and ion modifiers need to be added, and there is a sol-gel transformation process, solvent replacement is needed, the synthesis process is long and complicated, the physical and chemical structure of the aerogel is uncontrollable, and the structure-activity relationship between the fiber aerogel physical and chemical structure and protein adsorption is not clear.

[0023] 2) The present application uses thermoplastic nanofibers with rich active functional groups on the surface as the building block material of aerogel, directly prepares a suspension, freeze-dries to form an aerogel, and then is shaped after thermal crosslinking, without the need for a complex and time-consuming sol-gel process, overcoming the deficiencies of traditional silica aerogels such as weak strain (poor toughness and high brittleness), which not only reduces the addition of other chemical reagents in the shaping process of nanofiber aerogel, but also provides target functional groups for subsequent modification and application of aerogel materials.

[0024] 3) In the present application, the long-range order of the nanofiber structure in the thermoplastic polymer nanofiber aerogel for protein adsorption separation makes the molecular structure of the material more regular and ordered, and the properties (volume, density, etc.) of the fiber suspension can be adjusted to achieve precise control of the bulk density and pore structure of the aerogel material. The size of the prepared aerogel material is not limited by the raw material; the ordered and regular pore structure and the excellent mass transfer capacity of the fiber and the rich functional groups on its surface are conducive to realizing the high throughput, high capacity and low pressure drop of the protein adsorption medium.

[0025] The three-dimensional thermoplastic polymer nanofiber aerogel for protein adsorption separation as described above has an adsorption effect of 2.1-3.5 g / g on lysozyme in protein, a resistance pressure drop of 0.03-1.5 psi, and a water flux of 1-3 x 10 4 L m.-2 h -1 , compared with traditional micro-nanoparticles (adsorption effect is 1.6-3.0 g / g, resistance pressure drop is greater than 5-20 psi, and water flux is less than 1.2 x 10 2 L m -2 h -1 ) adsorption effect is better, resistance pressure drop is smaller, water flux is larger, and adsorption efficiency is higher. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 SEM image of the thermoplastic nanofiber cross-point bonding fixed crosslinked aerogel prepared in Example 1;

[0027] Figure 2 SEM image of a three-dimensional thermoplastic polymer nanofiber aerogel for protein adsorption separation prepared in Example 1;

[0028] Figure 3 SEM image of a three-dimensional thermoplastic polymer nanofiber aerogel for protein adsorption separation prepared in Example 2;

[0029] Figure 4 Infrared spectrum of the aerogel prepared in Example 1. DETAILED DESCRIPTION

[0030] The application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the application and not to limit the scope of the application. In addition, it should be understood that those skilled in the art can make various modifications or changes to the application after reading the content taught by the application, and these equivalent forms also fall within the scope defined by the claims attached hereto.

[0031] The application provides a preparation method of a three-dimensional thermoplastic polymer nanofiber aerogel for protein adsorption separation, and the specific steps are as follows:

[0032] Step 1: thermoplastic nanofibers are prepared by melt blending phase separation method of thermoplastic polymers and cellulose acetate butyrate;

[0033] Step 2: the thermoplastic nanofibers and the crosslinking agent are dispersed in a solvent to form a suspension;

[0034] Step 3: the suspension is freeze-dried to form an uncrosslinked thermoplastic polymer nanofiber aerogel;

[0035] Step 4: the uncrosslinked aerogel is subjected to crosslinking stabilization treatment, and the three-dimensional thermoplastic polymer nanofiber aerogel material with fiber cross-point bonding fixation is obtained after washing and freeze-drying;

[0036] Step 5: The three-dimensional thermoplastic polymer nanofiber aerogel is completely immersed in the protein modification solution for 30-60 min, and after freeze-drying and thermal grafting treatment, the three-dimensional thermoplastic polymer nanofiber aerogel for protein adsorption and separation is obtained after washing.

[0037] The specific raw materials, proportions, reaction conditions, and performance testing of the prepared three-dimensional thermoplastic polymer nanofiber aerogel are described in detail below. The raw materials in the examples and comparative examples are not specially mentioned and can be purchased from biochemical product companies.

[0038] Example 1

[0039] Step 1: 100 g of ethylene-vinyl alcohol copolymer (PE-co-PVA) and 400 g of cellulose acetate butyrate (CAB) are added to a twin-screw extruder, and a multi-component blended fiber with nanoscale dispersion of the dispersed phase in the matrix is obtained by melt blending phase separation method (twin-screw zone temperature 220-235°C, stretching air speed: 300 m / s; air cooling); the CAB matrix phase component in the blended fiber is dissolved and removed by Soxhlet extraction method at room temperature using acetone (consumption about 40 L) as the solvent, and PE-co-PVA nanofiber material is obtained, and the diameter of the micro-nano fiber is observed by scanning electron microscopy to be in the range of 50-300 nm.

[0040] Step 2: The PE-co-PVA nanofiber and glutaraldehyde (ratio 0.1 g: 175 uL) are dispersed in a mixture of acetic acid solution (1 wt%) and tert-butyl alcohol (volume ratio 4:1) to form a suspension with a PE-co-PVA nanofiber mass fraction of 0.1 wt%.

[0041] Step 3: The suspension is pre-cooled in a -80°C refrigerator for 36 h, then placed in a cold trap, and freeze-dried at -40°C and 0.5 pa for 56 h to form an uncrosslinked thermoplastic nanofiber aerogel.

[0042] Step 4: The uncrosslinked thermoplastic nanofiber is subjected to thermal crosslinking treatment at 75°C for 4 h in a normal pressure air atmosphere, and after the same freeze-drying method as in Step 3, a thermoplastic nanofiber aerogel with crosslinking point adhesion fixation is obtained, as shown in Figure 1

[0043] ​Fifth step: the thermoplastic polymer nanofiber aerogel is completely immersed in a modification liquid composed of butane tetracarboxylic acid, sodium hypophosphite and water for 30 min (catalyst is sodium hypophosphite, the mass ratio of butane tetracarboxylic acid to sodium hypophosphite is 8:5, and the content of butane tetracarboxylic acid in the modification liquid is 8 wt%). After being treated by the freeze-drying method as in the third step, the thermografting treatment is performed in an air atmosphere at normal pressure for 10 min (temperature range is 140-160°C), and the final thermoplastic polymer nanofiber aerogel for protein adsorption and separation is obtained after cleaning, as shown in Figure 2 Fig. 2, which is prepared by grafting butane tetracarboxylic acid on PE-co-PVA nanofiber. The modifier is not only grafted on the surface of the fiber, but also cross-linked between the fibers to form a network structure. The bulk density of the thermoplastic polymer nanofiber aerogel is 10 mg / cm 3 , the average pore size is 2 μm, the specific surface area is 800 m 2 / g, and the adsorption effect on lysozyme in a mixed protein liquid is 2.5-3.3 g / g. After elution and separation by an elution means (low pH value solution or high salt concentration solution), the eluate is purified to realize the adsorption, separation and purification of the protein.

[0044] Figure 4 In the infrared spectrum, EVOH NFAs is the aerogel in which the crosslinking of the thermoplastic nanofiber crosslinking points is fixed by the adhesion in 1; EVOH / BTCA NFAs is the thermoplastic polymer nanofiber aerogel for protein adsorption and separation in 1; and EVOH / BTCA NFAs treated with NaOH is the thermoplastic polymer nanofiber aerogel for protein adsorption and separation in 1 treated with sodium hydroxide.

[0045] Example 2

[0046] First step: 100 g of ethylene-vinyl alcohol copolymer (PE-co-PVA) and 300 g of cellulose acetate butyrate (CAB) are added into a twin-screw extruder, and a multi-component blended fiber in which the dispersed phase is dispersed in the matrix in nanometer scale is obtained by melt blending phase separation method (the temperature of each zone of the twin-screw is 230-250°C, the stretching air speed is 600 m / s, and the air ring cooling is used); the CAB matrix phase component in the blended fiber is dissolved and removed by Soxhlet extraction method at room temperature using acetone (the consumption is about 40 L) as the solvent, and thus PE-co-PVA nanofiber material is obtained. The diameter of the micro-nanofiber is observed by scanning electron microscope to be in the range of 50-260 nm.

[0047] Second step: the PE-co-PVA nanofiber and glutaraldehyde (the ratio is 0.1 g:175 uL) are dispersed in a mixed solvent of acetic acid solution (1 wt%) and tert-butyl alcohol (the volume ratio is 4:1) to form a suspension with a mass fraction of 0.1 wt% of the PE-co-PVA nanofiber.

[0048] Third step: The suspension was pre-cooled in the refrigerator at -80℃ for 12h, then placed in a cold trap, freeze-dried at -40℃, 0.5pa for 72h to form uncrosslinked thermoplastic nanofiber aerogel.

[0049] Fourth step: The uncrosslinked thermoplastic nanofiber was subjected to thermal crosslinking treatment at 75℃ for 4h in air atmosphere, and after the same freeze-drying method as the third step, the thermoplastic nanofiber aerogel with crosslinked fixed point adhesion was obtained.

[0050] Fifth step: The thermoplastic polymer nanofiber aerogel was completely immersed in a mixed solution of citric acid, polyphosphoric acid and water for 60min (the catalyst was sodium hypophosphite, the mass ratio of citric acid to polyphosphoric acid was 10:5, and the content of citric acid in the modification solution was 10wt%). After the same freeze-drying method as the third step, the thermografting treatment was carried out in air atmosphere for 1h (the temperature range was 90-110℃), and after washing, the final thermoplastic polymer nanofiber aerogel for protein adsorption and separation was prepared, as shown in Figure 3 , which was prepared by grafting citric acid on PE-co-PVA nanofiber. The modifier was not only grafted on the fiber surface, but also crosslinked between the fibers to form a network structure. The bulk density was 10mg / cm 3 , the average pore size was 2μm, the specific surface area was 900m 2 / g, and the adsorption effect of lysozyme in mixed protein liquid was 2.5-3.3g / g. After elution and separation by elution means (low pH value solution or high salt concentration solution), the eluate was purified to realize the adsorption, separation and purification of protein.

[0051] Example 3

[0052] First step: 100g of ethylene-acrylic acid copolymer (PE-co-AA) and 600g of cellulose acetate butyrate (CAB) were added to a twin-screw extruder to obtain a multi-component blended fiber with nanoscale dispersion of the dispersed phase in the matrix by melt blending phase separation method (the temperature of each zone of the twin-screw was 220-235℃, the stretching air speed was 500m / s, and the air ring cooling was used); the CAB matrix phase component in the blended fiber was dissolved and removed by Soxhlet extraction method at room temperature using acetone solvent (the consumption was about 40L), and PE-co-AA nanofiber material was obtained. The diameter of the micro-nano fiber was in the range of 60-280nm observed by scanning electron microscope.

[0053] Second step: PE-co-AA nanofiber and polyamide-epichlorohydrin resin (mass ratio 1:1.5) were dispersed in a mixed solvent of water and tert-butyl alcohol (volume ratio 4:1) to form a suspension with a mass fraction of PE-co-AA nanofiber of 10wt%.

[0054] Third step: the suspension is pre-cooled in a -80°C refrigerator for 48 hours, then placed in a cold trap, and freeze-dried at -40°C and 1.0 pa for 48 hours to form uncrosslinked thermoplastic nanofiber aerogel.

[0055] Fourth step: the uncrosslinked thermoplastic nanofiber is subjected to microwave irradiation (frequency of 300-300000 MHz, wavelength of 1 m-1 mm) for 2-4 hours under normal pressure air atmosphere, and is treated by the freeze-drying method as in the third step to obtain thermoplastic nanofiber crosslinking point adhesion fixed aerogel.

[0056] Fifth step: the thermoplastic polymer nanofiber aerogel is completely immersed in a mixed solution of citric acid, sodium hypophosphite and water for 40 minutes (catalyst is sodium hypophosphite, mass ratio of citric acid to sodium hypophosphite is 10:1, and content of citric acid in the modification liquid is 16 wt%). After treatment by the freeze-drying method as in the third step, the thermografting treatment is carried out for 1 hour (temperature range is 90-110°C) under normal pressure air atmosphere, and the final thermoplastic polymer nanofiber aerogel for protein adsorption and separation is obtained after cleaning, which is prepared from PE-co-AA nanofiber grafted with citric acid. The modifier is not only grafted on the surface of the fiber, but also crosslinked between the fibers to form a network structure, with a bulk density of 100 mg / cm 3 , an average pore size of 40 μm, a surface area of 70 m 2 / g, and an adsorption effect of 0.5-1.8 g / g on lysozyme in a mixed protein liquid. After elution and separation by means of elution (low pH value solution or high salt concentration solution), the eluate is purified to realize the adsorption, separation and purification of proteins.

[0057] Example 4

[0058] First step: 100 g of ethylene-acrylic acid copolymer (PE-co-AA) and 400 g of cellulose acetate butyrate (CAB) are added to a twin-screw extruder, and a multi-component blended fiber with nanoscale dispersion of the dispersed phase in the matrix is obtained by melt blending phase separation method (twin-screw zone temperature is 240-250°C, drawing air speed: 450 m / s; air ring cooling); the CAB matrix phase component in the blended fiber is dissolved and removed by Soxhlet extraction method at room temperature using acetone solvent (consumption is about 40 L), and PE-co-AA nanofiber material is obtained, and the diameter of the micro-nano fiber is observed by scanning electron microscope to be in the range of 80-280 nm.

[0059] Second step: PE-co-AA nanofiber and polyamide-epichlorohydrin resin (mass ratio 1:1.5) were dispersed in a mixed solvent of water and tert-butyl alcohol (volume ratio 4:1) to form a suspension with a PE-co-AA nanofiber mass fraction of 1wt%.

[0060] Third step: The suspension was pre-cooled in a -80°C refrigerator for 48h, then placed in a cold trap, and freeze-dried at -40°C and 1.0pa for 48h to form uncrosslinked thermoplastic nanofiber aerogel.

[0061] Fourth step: The uncrosslinked thermoplastic nanofiber was crosslinked by UV irradiation (wavelength 280-400nm, power 60W) for 30min in an air atmosphere at normal pressure, and then treated by the freeze-drying method of the third step to obtain thermoplastic nanofiber aerogel with crosslinked fixed points.

[0062] Fifth step: The thermoplastic polymer nanofiber aerogel was completely immersed in a mixed solution of citric acid, polyphosphoric acid and water for 30min (catalyst: sodium hypophosphite, mass ratio of citric acid to sodium hypophosphite 10:1, citric acid content in the modification liquid 10wt%). After treatment by the freeze-drying method of the third step, the sample was subjected to thermal grafting treatment for 1h (temperature range 90-110°C) in an air atmosphere at normal pressure. After washing, the final thermoplastic polymer nanofiber aerogel for protein adsorption and separation was prepared from PE-co-AA nanofiber grafted with citric acid. The modifier was not only grafted on the fiber surface, but also crosslinked between the fibers to form a network structure. The bulk density was 10mg / cm 3 , the average pore size was 45μm, and the specific surface area was 370m 2 / g. The adsorption effect on lysozyme in a mixed protein liquid was 1.5-2.8g / g. After elution and separation by means of a low pH solution or a high salt concentration solution, the eluate was purified to achieve protein adsorption, separation and purification.

[0063] Example 5

[0064] First step: 100g of ethylene-methacrylic acid copolymer (PE-co-MAA) and 800g of cellulose acetate butyrate (CAB) were added to a twin-screw extruder, and a multi-component blended fiber with nanoscale dispersed dispersed phase in the matrix was obtained by melt blending phase separation (twin-screw zone temperature 230-250°C, drawing air speed: 600m / s; air ring cooling). The CAB matrix phase component in the blended fiber was dissolved and removed by Soxhlet extraction at room temperature using acetone solvent (consumption about 40L) to obtain PE-co-MAA nanofiber material. Scanning electron microscopy showed that the diameter of the micro-nano fiber was in the range of 100-300nm.

[0065] Second step: PE-co-MAA nanofiber and diisocyanate (ratio 0.1 g: 175 uL) were dispersed in a mixed solvent of water and t-butyl alcohol (volume ratio 4:1) to form a suspension of PE-co-MAA nanofiber with a mass fraction of 1 wt%.

[0066] Third step: The suspension was pre-cooled in a -80°C refrigerator for 48 h, then placed in a cold trap, and freeze-dried at -40°C and 0.1 pa for 48 h to form uncrosslinked thermoplastic nanofiber aerogel.

[0067] Fourth step: The uncrosslinked thermoplastic nanofiber was subjected to thermal crosslinking treatment at 100°C for 3 h in an air atmosphere at normal pressure, and then treated by the freeze-drying method of the third step to obtain thermoplastic nanofiber aerogel with crosslinking points fixed by interlacing.

[0068] Fifth step: The thermoplastic polymer nanofiber aerogel was completely immersed in a mixed solution of citric acid, polyphosphoric acid, and water for 50 min (the catalyst was polyphosphoric acid, the mass ratio of citric acid to polyphosphoric acid was 10:1, and the content of citric acid in the modification liquid was 8 wt%). After treatment by the freeze-drying method of the third step, the thermal grafting treatment was carried out in an air atmosphere at normal pressure for 1 h (temperature range 90-110°C). After washing, the final thermoplastic polymer nanofiber aerogel for protein adsorption and separation was prepared by grafting citric acid onto PE-co-MAA nanofiber. The modifier was not only grafted on the fiber surface but also crosslinked between the fibers to form a network structure. The bulk density was 10 mg / cm 3 , the average pore size was 38 pm, the specific surface area was 760 m 2 / g, and the adsorption effect on lysozyme in a mixed protein liquid was 1.8-2.8 g / g. After elution and separation by an elution means (low pH value solution or high salt concentration solution), the eluate was purified to realize the adsorption, separation, and purification of proteins.

[0069] Example 6

[0070] First step: 100 g of ethylene-methacrylic acid copolymer (PE-co-MAA) and 400 g of cellulose acetate butyrate (CAB) were added to a twin-screw extruder to obtain a multi-component blended fiber with nanoscale dispersion of the dispersed phase in the matrix by melt blending phase separation method (twin-screw zone temperature 220-240°C, drawing air speed: 600 m / s; air ring cooling); the CAB matrix phase component in the blended fiber was dissolved and removed by Soxhlet extraction method at room temperature using acetone solvent (consumption about 40 L) to obtain PE-co-MAA nanofiber material. Scanning electron microscopy observation showed that the diameter of the micro-nano fiber was in the range of 50-200 nm.

[0071] Second step: disperse PE-co-MAA nanofiber and polyamide-epichlorohydrin resin (mass ratio 1:1.5) in a mixed solvent of water and tert-butyl alcohol (volume ratio 4:1) to form a suspension with a PE-co-MAA nanofiber mass fraction of 1wt%.

[0072] Third step: pre-cool the suspension in a -80℃ refrigerator for 48h, then place it in a cold trap, freeze-dry at -40℃ and 0.1pa for 48h to form uncrosslinked thermoplastic nanofiber aerogel.

[0073] Fourth step: ultrasonic crosslinking (frequency 20000-100000Hz, power 0.5-2.5W / cm 2 ) treatment of the uncrosslinked thermoplastic nanofiber in an air atmosphere at normal pressure for 30min, followed by the freeze-drying method of the third step to obtain thermoplastic nanofiber aerogel with crosslinking fixed by interlaced point bonding.

[0074] Fifth step: immerse the thermoplastic polymer nanofiber aerogel in a mixed solution of citric acid, polyphosphoric acid and water for 45min (catalyst is polyphosphoric acid, mass ratio of citric acid to polyphosphoric acid is 10:2, citric acid content in the modification liquid is 10wt%). After the freeze-drying method of the third step, perform thermal grafting treatment in an air atmosphere at normal pressure for 1h (temperature range 90-110℃), and finally obtain the thermoplastic polymer nanofiber aerogel for protein adsorption and separation prepared by grafting citric acid onto PE-co-MAA nanofiber. The modifier is not only grafted on the fiber surface, but also crosslinked between the fibers to form a network structure, with a bulk density of 10mg / cm 3 , an average pore size of 110μm, a specific surface area of 560m 2 / g, and an adsorption effect on lysozyme in a mixed protein liquid of 1.8-2.8g / g. After elution and separation by elution means (low pH solution or high salt concentration solution), the eluate is purified to achieve protein adsorption, separation and purification.

[0075] Example 7

[0076] First step: 100g of maleic anhydride grafted polyethylene (PE-g-MAH) and 400g of cellulose acetate butyrate (CAB) were added into a twin-screw extruder, and a multi-component blend fiber with nanoscale dispersed phase in the matrix was obtained by melt blending phase separation method (the temperature of each zone of the twin-screw was 235-250℃, the stretching air speed was 350m / s, and the air ring cooling was used); the CAB matrix phase component in the blend fiber was dissolved and removed by Soxhlet extraction method at room temperature using acetone solvent (the consumption was about 40L), and thus PE-g-MAH nanofiber material was obtained; the diameter of the micro-nano fiber was observed by scanning electron microscopy, and the diameter range was 50-250nm.

[0077] Second step: the PE-co-MAH nanofiber and polyamide-epichlorohydrin resin (mass ratio 1:1.5) were dispersed in a mixed solution of water and tert-butyl alcohol for 60min (volume ratio 4:1) to form a suspension with a PE-co-MAH nanofiber mass fraction of 0.1wt%.

[0078] Third step: the suspension was pre-cooled in a-80℃ refrigerator for 48h, and then placed in a cold trap, and freeze-dried at-40℃ and 0.1pa for 48h to form uncrosslinked thermoplastic nanofiber aerogel.

[0079] Fourth step: the uncrosslinked thermoplastic nanofiber was subjected to thermal crosslinking treatment at 100℃ for 3h in an air atmosphere, and then treated by the freeze-drying method of the third step to obtain thermoplastic nanofiber aerogel with crosslinking fixed by interlaced point bonding.

[0080] Fifth step: the thermoplastic polymer nanofiber aerogel was completely immersed in a mixed solution of citric acid, polyphosphoric acid and water (the catalyst was polyphosphoric acid, the mass ratio of citric acid to polyphosphoric acid was 10:2, and the citric acid content in the modifier solution was 10wt%). After treatment by the freeze-drying method of the third step, the thermografting treatment was carried out at 90-110℃ for 1h in an air atmosphere, and the final thermoplastic polymer nanofiber aerogel for protein adsorption and separation was obtained after washing, which was prepared by grafting citric acid on PE-co-MAH nanofiber. The modifier was not only grafted on the fiber surface, but also crosslinked between the fibers to form a network structure, and the bulk density was 1mg / cm 3 , the average pore size was 80μm, the specific surface area was 750m 2 / g, and the adsorption effect on lysozyme in a mixed protein liquid was 2-3g / g. After elution and separation by elution means (low pH value solution or high salt concentration solution), the eluate was purified to realize the adsorption, separation and purification of proteins.

[0081] Example 8

[0082] First step: 100g of maleic anhydride grafted polyethylene (PE-g-MAH) and 400g of cellulose acetate butyrate (CAB) were added into a twin-screw extruder, and a multi-component blend fiber with nanoscale dispersed phase in the matrix was obtained by melt blending phase separation method (the temperature of each zone of the twin-screw was 225-235℃, the stretching air speed was 600m / s, and the air ring cooling was used); the CAB matrix phase component in the blend fiber was dissolved and removed by Soxhlet extraction method at room temperature using acetone solvent (the consumption was about 40L), and thus PE-g-MAH nanofiber material was obtained; the diameter of the micro-nano fiber was observed by scanning electron microscopy, and the diameter range was 80-300nm.

[0083] Second step: the PE-co-MAH nanofiber and diisocyanate (the ratio was 0.1g:175uL) were dispersed in a mixed solution of water and tert-butyl alcohol (the volume ratio was 4:1) to form a suspension with a PE-co-MAH nanofiber mass fraction of 0.1wt%.

[0084] Third step: the suspension was pre-cooled in a-80℃ refrigerator for 48h, and then placed in a cold trap, and freeze-dried at-40℃ and 0.1pa for 48h to form uncrosslinked thermoplastic nanofiber aerogel.

[0085] Fourth step: the uncrosslinked thermoplastic nanofiber was subjected to microwave irradiation (the frequency was 300-300000MHz, and the wavelength was 1m-1mm) for 2-4h under normal pressure air atmosphere, and then subjected to the freeze-drying method as in the third step to obtain thermoplastic nanofiber aerogel with crosslinking fixed by point adhesion.

[0086] Fifth step: the thermoplastic polymer nanofiber aerogel was completely immersed in a mixed solution of citric acid, polyphosphoric acid and water for 60min (the catalyst was polyphosphoric acid, the mass ratio of citric acid to polyphosphoric acid was 10:2, and the citric acid content in the modifier solution was 10wt%), and then subjected to the freeze-drying method as in the third step, and then subjected to thermal grafting treatment for 1h (the temperature range was 90-110℃) under normal pressure air atmosphere, and finally the thermoplastic polymer nanofiber aerogel for protein adsorption and separation was obtained after washing, which was prepared from PE-co-MAH nanofiber grafted with citric acid, and the modifier was not only grafted on the fiber surface, but also crosslinked between the fibers to form a network structure, and the bulk density was 1mg / cm 3 , the average pore size was 8μm, and the specific surface area was 470m 2 / g, and the adsorption effect on lysozyme in protein was 1.6-3g / g.

[0087] Comparative example 1

[0088] A preparation method of silica aerogel, comprising the following steps:

[0089] First step: preparing sol by stirring polysiloxane, water, solvent and catalyst in different proportions, and then preparing wet gel by sol-gel transition process, wherein the volume ratio of polysiloxane, water, solvent and catalyst is 1:3-15:0.5-1.0:0.02-0.1; (the polysiloxane can be tetramethyl orthosilicate, tetraethyl orthosilicate, industrial-grade raw material E·40, E32 or E28, etc., the solvent can be ethanol, isopropyl alcohol, acetone, butanone or acetonitrile, etc., and the catalyst can be sulfuric acid, nitric acid, hydrofluoric acid, hydrochloric acid, oxalic acid or ammonia, etc.)

[0090] Second step: immersing the obtained wet gel in surface modification liquid for a period of time (30-72 hours) for surface modification, and the volume ratio of surface modification liquid to modification liquid solvent is 1:5-15; (the surface modification liquid is one of trimethylchlorosilane, hexamethyldisiloxane, dimethyl monoethoxysilane, methyl diethoxysilane or fluorosilane, and the modification liquid solvent is hexamethyldisiloxane, cyclohexane, n-hexane, isopropyl alcohol, hexamethyldisiloxane cyclohexane mixture, n-hexane isopropyl alcohol mixture or hexamethyldisiloxane n-hexane mixture)

[0091] Third step: taking out the wet gel for normal pressure drying and segmented heat treatment, i.e. first treating at 100-200℃ for 2-5 hours, then treating at 300-350℃ for 3-7 hours, and finally treating at 500-600℃ for 8-15 hours, to obtain silica aerogel;

[0092] As shown in Figure 2 the final prepared silica aerogel has a density of 20-30mg / cm 3 , an average pore size of 5-30nm, a specific surface area of 60-200m 2 / g, and an adsorption effect on lysozyme in mixed protein liquid of 0.5-0.8g / g.

[0093] As can be seen by comparing Examples 1-8 with Comparative Example 1, the three-dimensional thermoplastic polymer nanofiber aerogel for protein adsorption and separation obtained by the present application has higher performance than the silica aerogel in Comparative Example 1.

[0094] The above description is only a preferred specific embodiment of the present application, and the protection scope of the present application is not limited thereto, and any simple change or equivalent replacement of the technical solution within the technical range disclosed by the present application can fall within the protection scope of the present application.

Claims

1. A method for the preparation of three-dimensional thermoplastic polymer nanofiber aerogels for protein adsorption separations, characterized by, The specific steps are, The first step: the thermoplastic polymer and cellulose acetate butyrate are prepared into thermoplastic nanofibers by melt blending phase separation method; The second step: the thermoplastic nanofibers and crosslinking agent are dispersed in a solvent to form a suspension; The third step: the suspension is freeze-dried to form uncrosslinked thermoplastic polymer nanofiber aerogel; The fourth step: the uncrosslinked aerogel is subjected to crosslinking stabilization treatment, and the three-dimensional thermoplastic polymer nanofiber aerogel material with fiber interpenetration point bonding is obtained after washing and freeze-drying; The fifth step: the three-dimensional thermoplastic polymer nanofiber aerogel is completely immersed in a protein modification liquid for 30-60 min, and then subjected to thermal grafting treatment after freeze-drying, to obtain a three-dimensional thermoplastic polymer nanofiber aerogel for protein adsorption and separation after washing, In the second step, the crosslinking agent is any one or a combination of glutaraldehyde, glycerol, borax, diisocyanate and polyamide-epichlorohydrin resin, In the fifth step, the modification liquid is a mixed liquid prepared by mixing a modifier, a catalyst and a solvent; the modifier is any one of butane tetracarboxylic acid and citric acid; the catalyst is polyphosphoric acid or sodium hypophosphite; and the solvent is any one or a combination of water, acetone, tetrahydrofuran, n-hexane, toluene, DMSO and N,N-dimethylformamide.

2. The method of claim 1, wherein the three-dimensional thermoplastic polymer nanofiber aerogel for protein adsorption and separation is prepared by the steps of: In the first step, the mass ratio of the thermoplastic polymer to cellulose acetate butyrate is 1:1.5-39; and the thermoplastic polymer is any one or a combination of polyolefin-vinyl alcohol copolymer, polyolefin-acrylic acid copolymer, polyolefin-methacrylic acid copolymer, maleic anhydride grafted polyolefin and polyamide.

3. A method for the preparation of three-dimensional thermoplastic polymer nanofiber aerogels for protein adsorption separation according to claim 1, characterized in that, In the first step, the phase separation method has a temperature of 220-250 DEG C and a stretching air speed of 300-600 m / s; Air blowing and cooling.

4. The method of claim 1, wherein the three-dimensional thermoplastic polymer nanofiber aerogel for protein adsorption and separation is characterized by, In the second step, the mass fraction of the thermoplastic nanofiber in the suspension is 0.01-50%, the average diameter of the thermoplastic nanofiber is 50-300 nm, and the average length-diameter ratio of the fiber is 5-50000; and the solvent is any one or a combination of water, methanol, ethanol, propanol, isopropanol, tert-butyl alcohol, acetone, acetic acid, sulfuric acid and hydrochloric acid.

5. The method of claim 1, wherein the three-dimensional thermoplastic polymer nanofiber aerogel for protein adsorption and separation is characterized by, In the third, fourth and fifth steps, the freeze-drying process is precooling and drying, i.e. freezing in a-80 DEG C freezer for 12-48 h and drying in a-40 DEG C cold trap with a pressure of 0.1-1.0 Pa for 48-72 h.

6. The method of claim 1, wherein the three-dimensional thermoplastic polymer nanofiber aerogel for protein adsorption and separation is prepared by the steps of: In the fourth step, the crosslinking stabilization treatment is any one or a combination of thermal crosslinking, ultrasonic crosslinking, microwave irradiation crosslinking, infrared irradiation crosslinking, ultraviolet irradiation crosslinking and plasma irradiation crosslinking.

7. A three-dimensional thermoplastic polymer nanofiber aerogel for protein adsorption and separation prepared by the preparation method of claim 1-6.

8. A three-dimensional thermoplastic polymer nanofiber aerogel for protein adsorption separation according to claim 7, characterized in that, The three-dimensional thermoplastic polymer nanofiber aerogel for protein adsorption separation has the following properties: a bulk density of 1-500 mg / cm 3 , an average pore size of 0.1-200 μm, and a specific surface area of 20-2000 m 2 / g. The fibers penetrate and interpenetrate each other to form a connected pore structure.

Images