A magnetically recyclable core-shell hydrogel microsphere and its preparation method and application

Abstract

The present invention discloses a magnetically recyclable core-shell hydrogel microsphere and its preparation method and application. A hydrogel-based microsphere medium with a core-shell chamber structure is constructed by coaxial microfluidic technology, and the magnetic core directional encapsulation and shell dynamic covalent modification strategy are combined to achieve efficient specific adsorption of lactose molecules and rapid magnetic separation of microspheres. Based on the core-shell functional zoning synergistic mechanism, the magnetic core provides high magnetic responsiveness to achieve rapid recovery, and the shell hydrogel network captures lactose through dynamic covalent bonds. At the same time, its swelling steric hindrance and surface charge repulsion effect block milk protein adsorption, and the efficient removal of lactose and the preservation of nutrients are simultaneously completed under mild operating conditions, breaking through the bottleneck that active ingredients and separation efficiency cannot be achieved at the same time in traditional processes. By adjusting parameters such as the core-shell size ratio and the functional group grafting density, the synergistic optimization of the cyclic adsorption function is achieved. This technology provides an innovative material platform for the large-scale production of low-lactose buffalo milk and the closed-loop recovery of lactose resources.

Description

Technical Field

[0001] The invention belongs to the technical field of lactose separation, and in particular relates to a buffalo milk lactose adsorption separation technology, and specifically is a magnetically recoverable core-shell hydrogel microsphere used for buffalo milk lactose adsorption separation and a preparation method thereof. Background Art

[0002] With the development of national health concepts, zero-lactose buffalo milk has gradually generated more market demand among people with lactose intolerance and impaired glucose tolerance. Due to the high lactose content and strong heat sensitivity of milk protein in buffalo milk, traditional lactose removal technology faces multiple challenges. Existing non-adsorption technologies such as enzymatic hydrolysis require the addition of lactase. Although it can hydrolyze lactose, the residual enzymatic hydrolysis products may change the flavor of milk, and the cost of enzyme preparations is high; the ion exchange method adsorbs lactose through resin, but the resin regeneration requires strong acid / alkali washing, which can easily cause the loss of nutrients such as calcium and lactoferrin, and the risk of chemical residues is difficult to avoid. Although traditional adsorption materials such as activated carbon are low in cost, they have poor adsorption selectivity, adsorb proteins and minerals at the same time, and are difficult to separate efficiently from liquid milk. Additional centrifugation or filtration steps are required, and the process is complicated.

[0003] Therefore, in the current technology system, enzymatic hydrolysis sacrifices flavor and cost, ion exchange threatens food safety, and traditional adsorption materials are limited by separation efficiency and selectivity. In view of the high protein and high lactose characteristics of buffalo milk, it is urgent to develop a lactose removal technology that has high adsorption capacity, precise selectivity, rapid separation ability and meets food-grade safety standards.

[0004] At present, adsorption separation technology based on hydrogel microspheres has shown unique potential: its three-dimensional network structure can provide high specific area and controllable pore size distribution, and can achieve lactose-specific recognition through functional group modification (such as phenylboronic acid and amino group); at the same time, the biocompatibility and swelling properties of hydrogels can minimize the interference with the structure of milk proteins. Further combined with magnetic control separation technology, the external magnetic field can be used to achieve rapid recovery of microspheres, which can avoid the efficiency bottleneck caused by traditional centrifugation / filtration and provide the possibility for continuous production.

[0005] However, there is still room for optimization of the existing magnetically controlled hydrogel microsphere system: traditional solid microspheres are limited by internal mass transfer resistance, and it is difficult to break through the adsorption capacity; magnetic particles are directly doped into the hydrogel matrix, and long-term circulation may cause the magnetic response performance to decay. Summary of the invention

[0006] One of the purposes of the present invention is to provide a magnetically recoverable core-shell hydrogel microsphere and a preparation method thereof, in view of the problem that the existing solid microspheres are limited by the internal mass transfer resistance and the adsorption capacity is difficult to break through, so as to simultaneously improve the magnetic separation efficiency and lactose adsorption kinetics, and at the same time, the spatial barrier effect of the core-shell chamber on milk protein further enhances the selective retention.

[0007] Another object of the present invention is to provide a new use of the magnetically recoverable core-shell hydrogel microspheres for the adsorption and separation of lactose from buffalo milk, thereby opening up a new path for the high-quality production of low-lactose buffalo milk.

[0008] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is as follows:

[0009] In order to achieve the above first object, the present invention provides a method for preparing magnetically recyclable core-shell hydrogel microspheres, comprising the following steps:

[0010] S1. Synthetic SiO 2 Coated Fe 3 O 4 Magnetic nanoparticles;

[0011] S2, preparing phenylboronic acid grafted chitosan;

[0012] S3, dispersing the magnetic nanoparticles prepared in step S1 in a solution containing CaCl 2 The aqueous solution is used as the internal phase solution; the phenylboronic acid grafted chitosan and sodium alginate prepared in step S2 are dissolved in deionized water as the external phase solution; and core-shell hydrogel microspheres are prepared by a coaxial microfluidic device.

[0013] Specifically, in step S1, FeCl 3 6H 2 O and FeCl 2 ·4H 2 O was dissolved in deionized water at a molar ratio of 1.8:1-2.2:1, and ammonia water was added dropwise to pH 9.5-11.5 under nitrogen protection. The reaction was carried out at 75-85℃ for 0.8-1.2 h to obtain Fe 3 O 4 Nanoparticles; then add a mixture of ethyl orthosilicate and ethanol (volume ratio 1:8-1:12), react at 45-55°C for 5-7 h under the catalysis of ammonia water, and obtain SiO after magnetic separation and ethanol washing. 2 Coated Fe 3 O 4 Magnetic nanoparticles.

[0014] Preferably, the amount of tetraethyl orthosilicate added is Fe 3 O 4 The mass of the nanoparticles was 18-22%, the magnetic separation intensity after the reaction was 0.4-0.6 T, and the number of ethanol washings was ≥ 3 times; the prepared SiO 2 Coated Fe 3 O 4 In magnetic nanoparticles, Fe 3 O 4 The particle size is controlled to be 40-60 nm, SiO2 The shell thickness is 6-10 nm.

[0015] Specifically, in step S2, chitosan with a deacetylation degree of 85-95% is dissolved in a 0.8-1.2% acetic acid solution, 4-carboxyphenylboronic acid is added, EDC / NHS is used as a coupling agent, and the grafting reaction is carried out at 20-30° C. for 10-14 h. After purification by dialysis, freeze-drying is performed to obtain phenylboronic acid grafted chitosan.

[0016] Preferably, the molar ratio of chitosan to 4-carboxyphenylboronic acid is 1:1.0-1.4; the molar ratio of coupling agent is EDC to NHS is 1:1.3-1.7; the grafting rate of phenylboronic acid grafted chitosan obtained is ≥12%.

[0017] Preferably, the pH of the grafting reaction system is controlled at 4.8-5.7, and the dialysis cut-off molecular weight is 3.0-4.0 kDa; the grafting rate of the obtained phenylboronic acid grafted chitosan is 16-20%, and the intrinsic viscosity of the product is 110-160 mL / g.

[0018] Preferably, the CaCl 2 The concentration of the aqueous solution is 0.25-0.35 M, and the solid content of magnetic nanoparticles in the obtained inner phase solution is 7-9 wt%; the mass ratio of phenylboronic acid grafted chitosan to sodium alginate is 1:1.8-2.2, and the total solid content in the obtained outer phase solution is 3.5-4.5 wt%; in the coaxial microfluidic device, the diameter of the coaxial inner phase tube is 180-220 μm, the diameter of the outer phase tube is 480-520 μm, and the microspheres are formed at an inner and outer phase flow rate ratio of 1:10-1:14, and Ca 2+ Core-shell hydrogel microspheres were obtained by cross-linking and curing.

[0019] Furthermore, the magnetically recyclable core-shell hydrogel microspheres prepared by the above preparation method are also within the protection scope of the present invention.

[0020] Preferably, the prepared magnetically recyclable core-shell hydrogel microspheres have a particle size of 170-180 μm, Fe 3 O 4 Loading amount 12-15 wt%.

[0021] Specifically, the magnetically recoverable core-shell hydrogel microspheres were mixed with buffalo milk with a pH of 6.8-7.7 at a solid-liquid ratio of 1:35-45 g / mL at room temperature, adsorbed for 20-30 min under magnetic stirring (140-160 rpm), and the core-shell hydrogel microspheres were recovered within 2-4 min after applying a 0.3-0.5 T magnetic field, with a lactose adsorption rate of ≥80% and a milk protein retention rate of >90%. The recovered core-shell hydrogel microspheres were immersed in a pH 3.3-3.7 citric acid buffer (containing 0.25-0.35 M NaCl), fully shaken to desorb lactose, and rinsed with deionized water before reuse.

[0022] Preferably, when the magnetic field gradient is ≥60 T / m, the microsphere recovery rate is >99%. The adsorption time is 20 min, and the lactose adsorption rate is 93±2%. After desorption at 40°C for 20 min, the desorption efficiency is >95%, and the microsphere breakage rate is <2% / time. The magnetically recoverable core-shell hydrogel microspheres have an adsorption capacity retention rate of >80% after 50 cycles.

[0023] The present invention is based on the core-shell structure design and dynamic covalent modification synergistic strategy to achieve efficient lactose adsorption and highly selective retention of other nutrients such as milk protein. 2 @Fe 3 O 4 The synergistic effect of the magnetic core and the functionalized hydrogel shell forms a multi-level adsorption system, in which SiO 2 Coated Fe 3 O 4 The nanoparticles are quickly separated by an external magnetic field, and the phenylboronic acid groups grafted into the three-dimensional network of the shell hydrogel specifically bind to lactose through dynamic covalent bonds; the milk protein is effectively blocked due to the steric hindrance of the shell swelling and the surface charge repulsion effect, breaking through the technical bottleneck of low separation efficiency and large component loss of traditional adsorption materials. Lactose removal and milk protein retention are achieved simultaneously through a single adsorption-desorption cycle, and the natural flavor of buffalo milk and heat-sensitive active substances are completely maintained. The present invention can meet the dual needs of nutritional retention and processing safety in the development of low-lactose buffalo milk products, and promote the recycling of lactose resources and the green upgrading of dairy processing.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention solves the contradiction between adsorption capacity and component retention rate in the adsorption and separation of lactose from buffalo milk by developing controllable construction and dynamic covalent modification technology of core-shell microspheres. Compared with traditional enzymatic hydrolysis and ion exchange processes, this technology provides a more efficient and safe solution for the selective removal of lactose, has significant advantages in maintaining the retention rate of milk protein and minerals, and provides technical support for the nutritional preservation of low-lactose buffalo milk.

[0026] (2) In terms of structural design, the coaxial microfluidics technology is used to achieve precise control of the size and magnetic distribution of microspheres, and its monodispersity and shell confinement effect are significantly better than those of the traditional emulsion template method. This feature can reduce the breakage rate of microspheres, extend the cycle life, and provide a new path for improving the stability of continuous dairy processing.

[0027] (3) The preparation process strictly follows food-grade safety standards and uses hydrogel to coat magnetic particles to avoid the risk of metal ion migration. The regeneration process does not require strong acid / alkali treatment, eliminating chemical contamination from the source.

[0028] (4) The technical solution retains the adjustment space for key parameters. By adjusting the microsphere particle size, phenylboronic acid grafting density and magnetic field strength, it can adapt to different lactose concentrations and production scale requirements, providing multiple options for flexible process control.

[0029] (5) In terms of industrial compatibility, the magnetic separation module can be directly connected to the existing dairy production line without the need to modify the high-temperature sterilization or filling equipment. Its room temperature operating conditions are highly compatible with the traditional pasteurization process, greatly reducing the cost and risk of technical transformation.

[0030] (6) The universal nature of the technical principle gives it the potential for cross-field application. In addition to buffalo milk, it can also be extended to the removal of lactose from special milk sources such as goat milk and camel milk. It also provides a technical paradigm for the targeted adsorption of other small molecule impurities (such as cholesterol and allergens) in the food industry, thereby promoting the iteration of food precision manufacturing technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more clear.

[0032] Figure 1 This is the abstract diagram of the present invention, showing the entire process of core-shell microsphere preparation, lactose adsorption and magnetic separation.

[0033] Figure 2 The scanning electron microscope (SEM) image of the magnetic nanoparticles of the present invention shows a monodisperse structure.

[0034] Figure 3 The figure is a picture of the microsphere of the present invention under an optical microscope, showing an obvious core-shell structure.

[0035] Figure 4 The lactose adsorption kinetics of the microspheres of the present invention and the traditional resin were compared, and the adsorption rate within 30 minutes was >80%, which was significantly higher than the resin's 60%.

[0036] Figure 5 This is a physical picture of the microspheres of the present invention being collected in a solution under the attraction of a magnetic field.

[0037] Figure 6 The figure is a relationship diagram between the number of cycles of use of the microspheres of the present invention and the retention rate of the adsorption capacity. After 50 cycles, the retention rate is greater than 80%. DETAILED DESCRIPTION

[0038] The present invention can be better understood with reference to the following examples.

[0039] Figure 1 The process route for preparing magnetically recyclable core-shell hydrogel microspheres and the whole process of lactose adsorption and magnetic separation are given.

[0040] The method for preparing magnetically recyclable core-shell hydrogel microspheres of the present invention comprises the following steps:

[0041] S1. Synthetic SiO 2 Coated Fe 3 O 4 Magnetic nanoparticles;

[0042] S2, preparing phenylboronic acid grafted chitosan;

[0043] S3, dispersing the magnetic nanoparticles prepared in step S1 in a solution containing CaCl 2 The aqueous solution is used as the internal phase solution; the phenylboronic acid grafted chitosan and sodium alginate prepared in step S2 are dissolved in deionized water as the external phase solution; and core-shell hydrogel microspheres are prepared by a coaxial microfluidic device.

[0044] The prepared magnetically recyclable core-shell hydrogel microspheres are used for the adsorption and separation of buffalo milk lactose, and the specific method is:

[0045] The magnetically recyclable core-shell hydrogel microspheres were mixed with buffalo milk at pH 7.0-7.5 at room temperature. After magnetic stirring and adsorption, a magnetic field was applied to recover the core-shell hydrogel microspheres, which could achieve a lactose adsorption rate of ≥80% and a milk protein retention rate of >90%. The recovered core-shell hydrogel microspheres were immersed in a pH 3.5 citric acid buffer (containing 0.3 M NaCl), fully shaken to desorb lactose, and then rinsed with deionized water and reused. The magnetically recyclable core-shell hydrogel microspheres had an adsorption capacity retention rate of >80% after 50 cycles.

[0046] Example 1

[0047] S1、SiO 2 @Fe 3 O 4 Synthesis of magnetic nanoparticles:

[0048] FeCl 3 6H 2 O and FeCl 2 ·4H 2O was dissolved in deionized water at a molar ratio of 2:1, and ammonia water was added dropwise to pH 10-11 under nitrogen protection, and reacted at 80℃ for 1 h to obtain Fe 3 O 4 Nanoparticles ( Figure 2 Then, tetraethyl orthosilicate (TEOS) and ethanol (volume ratio 1:10) were added, and the mixture was reacted at 50 °C for 6 h under the catalysis of ammonia water. After magnetic separation and ethanol washing, SiO 2 @Fe 3 O 4 Magnetic nanoparticles (Fe 3 O 4 Particle size 50±5 nm, SiO 2 Shell thickness 8±1 nm).

[0049] S2, preparation of phenylboronic acid grafted chitosan:

[0050] Chitosan (deacetylation degree ≥ 90%) was dissolved in 1% acetic acid solution, 4-carboxyphenylboronic acid (molar ratio 1:1.2) was added, EDC / NHS (molar ratio 1:1.5) was used as coupling agent, and the reaction was carried out at 25°C for 12 h. The pH of the reaction solution was controlled at 5.0-5.5. After purification by dialysis (dialysis molecular weight cutoff 3.5 kDa), freeze-drying was performed to obtain 18±2% phenylboronic acid grafted chitosan with a product intrinsic viscosity of 120-150 mL / g.

[0051] S3. Coaxial microfluidic preparation of core-shell hydrogel microspheres:

[0052] Internal phase: SiO 2 @Fe 3 O 4 Dispersed in 0.3 M CaCl 2 in an aqueous solution (solid content 8 wt%);

[0053] External phase: phenylboronic acid grafted chitosan and sodium alginate (mass ratio 1:2) dissolved in deionized water (total solid content 4wt%);

[0054] Microspheres were formed by coaxial microfluidic needles (200 μm inner diameter / 500 μm outer diameter) with an inner-outer phase flow rate ratio of 1:12 and Ca 2+ Cross-linking (0.1 M CaCl 2 , 10 min) to obtain core-shell hydrogel microspheres ( Figure 3 ), particle size 180±20 μm, shell thickness 40±5 μm.

[0055] Example 2

[0056] S1、SiO 2 @Fe 3 O 4Synthesis of magnetic nanoparticles:

[0057] FeCl 3 6H 2 O and FeCl 2 ·4H 2 O was dissolved in deionized water at a molar ratio of 1.8:1, and ammonia water was added dropwise to pH 9.5 under nitrogen protection. The reaction was carried out at 75°C for 1.2 h to obtain Fe 3 O 4 Then, tetraethyl orthosilicate (TEOS) and ethanol (volume ratio 1:8) were added, and the mixture was reacted at 45 °C for 7 h under the catalysis of ammonia water. After magnetic separation (intensity 0.4 T) and ethanol washing for 3 times, SiO 2 @Fe 3 O 4 Magnetic nanoparticles (Fe 3 O 4 Particle size 40±3 nm, SiO 2 Shell thickness 6±1 nm).

[0058] S2, preparation of phenylboronic acid grafted chitosan:

[0059] Chitosan (deacetylation degree 85%) was dissolved in 0.8% acetic acid solution, 4-carboxyphenylboronic acid (molar ratio 1:1.0) was added, EDC / NHS (molar ratio 1:1.3) was used as coupling agent, and the reaction was carried out at 20°C for 14 h. The pH of the reaction solution was controlled at 4.8. After purification by dialysis (molecular weight cutoff 3.0 kDa), phenylboronic acid grafted chitosan (grafting rate 16±1%, intrinsic viscosity 110±10 mL / g) was obtained.

[0060] S3. Coaxial microfluidic preparation of core-shell hydrogel microspheres:

[0061] Internal phase: SiO 2 @Fe 3 O 4 Dispersed in 0.25 M CaCl 2 in an aqueous solution (solid content 7 wt%);

[0062] External phase: phenylboronic acid grafted chitosan and sodium alginate (mass ratio 1:1.8) dissolved in deionized water (total solid content 3.5wt%);

[0063] Microspheres were formed by coaxial microfluidic needles (180 μm inner diameter / 480 μm outer diameter) with an inner-outer phase flow rate ratio of 1:10 and Ca 2+ Cross-linking (0.1 M CaCl 2 , 10 min) to obtain core-shell hydrogel microspheres (particle size 170±10 μm, shell thickness 35±5 μm, Fe 3 O4 Loading amount 12±1 wt%).

[0064] Example 3

[0065] S1、SiO 2 @Fe 3 O 4 Synthesis of magnetic nanoparticles:

[0066] FeCl 3 6H 2 O and FeCl 2 ·4H 2 O was dissolved in deionized water at a molar ratio of 2.2:1, and ammonia water was added dropwise to pH 11.5 under nitrogen protection. The reaction was carried out at 85°C for 0.8 h to obtain Fe 3 O 4 Nanoparticles; then tetraethyl orthosilicate (TEOS) and ethanol (volume ratio 1:12) were added, reacted at 55 °C for 5 h under the catalysis of ammonia water, and SiO was obtained after magnetic separation (intensity 0.6 T) and ethanol washing 5 times. 2 @Fe 3 O 4 Magnetic nanoparticles (Fe 3 O 4 Particle size 60±5 nm, SiO 2 Shell thickness 10±1 nm).

[0067] S2, preparation of phenylboronic acid grafted chitosan:

[0068] Chitosan (deacetylation degree 95%) was dissolved in 1.2% acetic acid solution, 4-carboxyphenylboronic acid (molar ratio 1:1.4) was added, EDC / NHS (molar ratio 1:1.7) was used as coupling agent, and the reaction was carried out at 30°C for 10 h. The pH of the reaction solution was controlled at 5.7. After purification by dialysis (molecular weight cutoff 4.0 kDa), phenylboronic acid grafted chitosan (grafting rate 20±1%, intrinsic viscosity 160±15 mL / g) was obtained.

[0069] S3. Coaxial microfluidic preparation of core-shell hydrogel microspheres:

[0070] Internal phase: SiO 2 @Fe 3 O 4 Dispersed in 0.35 M CaCl 2 in an aqueous solution (solid content 9 wt%);

[0071] External phase: phenylboronic acid grafted chitosan and sodium alginate (mass ratio 1:2.2) dissolved in deionized water (total solid content 4.5wt%);

[0072] Microspheres were formed by coaxial microfluidic needles (inner diameter 220 μm / outer diameter 520 μm) with an inner-outer phase flow rate ratio of 1:14 and Ca 2+ Cross-linking (0.1 M CaCl 2 , 10 min) to obtain core-shell hydrogel microspheres (particle size 175±15 μm, shell thickness 45±5 μm, Fe 3 O 4 Loading amount 15±1 wt%).

[0073] Example 4

[0074] The lactose adsorption performance of the magnetically recyclable core-shell hydrogel microspheres prepared in Example 1 was tested:

[0075] The magnetically recyclable core-shell hydrogel microspheres prepared in Example 1 were mixed with buffalo milk (lactose 4.8 g / L, pH 7.0) at a solid-liquid ratio of 1:40, and adsorbed at 25°C with stirring (200 rpm) for 25 min before sampling and testing. Figure 4 As shown, it can be seen that the lactose adsorption rate of the microspheres of the present invention is greater than 80% within 30 minutes, which is significantly higher than the 60% of the traditional ion exchange resin, verifying the high efficiency of the dynamic covalent adsorption mechanism. The retention rate of lactoferrin is greater than 95%, confirming the protective effect of shell steric hindrance and charge repulsion on milk protein. The traditional ion exchange resin used in the comparative experiment is Amberlite IR120 Na type strong acid cation exchange resin (manufacturer: DuPont, USA).

[0076] Example 5

[0077] The regeneration and cyclic stability tests were performed on the magnetically recyclable core-shell hydrogel microspheres prepared in Example 1:

[0078] After the adsorption of Example 4 was completed, a magnetic field was applied to recover the core-shell hydrogel microspheres, and the recovered microspheres were immersed in a pH 3.5 citric acid buffer (containing 0.3 M NaCl) to desorb lactose. After 50 cycles, the adsorption capacity retention rate was >80% ( Figure 6 ), the microsphere breakage rate is less than 2% / time, and the magnetization intensity decay is less than 5%, which proves that the present invention has long-term cyclic stability.

[0079] The present invention provides a magnetically recyclable core-shell hydrogel microsphere and its preparation method and application ideas and methods. There are many methods and ways to implement the technical solution. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention. All components not specified in this embodiment can be implemented by existing technologies.

Claims

1. An application of magnetically recoverable core-shell hydrogel microspheres for the adsorption and separation of buffalo milk lactose, characterized in that: The magnetically recyclable core-shell hydrogel microspheres are prepared by the following steps: S1, synthesizing SiO2-coated Fe3O4 magnetic nanoparticles; S2, preparing phenylboronic acid grafted chitosan; S3, dispersing the magnetic nanoparticles prepared in step S1 in an aqueous solution containing CaCl2 as an internal phase solution; dissolving the phenylboronic acid grafted chitosan and sodium alginate prepared in step S2 in deionized water as an external phase solution; preparing core-shell hydrogel microspheres by a coaxial microfluidic device, and obtaining; In step S2, chitosan with a deacetylation degree of 85-95% is dissolved in a 0.8-1.2% acetic acid solution, 4-carboxyphenylboronic acid is added, EDC / NHS is used as a coupling agent, and the grafting reaction is carried out at 20-30° C. for 10-14 h, and the chitosan is freeze-dried after purification by dialysis to obtain phenylboronic acid grafted chitosan; In step S3, the concentration of the aqueous solution containing CaCl2 is 0.25-0.35 M, and the solid content of magnetic nanoparticles in the obtained inner phase solution is 7-9 wt%; the mass ratio of phenylboronic acid grafted chitosan to sodium alginate is 1:1.8-2.2, and the total solid content in the obtained outer phase solution is 3.5-4.5 wt%; in the coaxial microfluidic device, the diameter of the coaxial inner phase tube is 180-220 μm, the diameter of the outer phase tube is 480-520 μm, and the microspheres are formed at an inner and outer phase flow rate ratio of 1:10-1:14, and Ca 2+ Cross-linking and curing to obtain core-shell hydrogel microspheres; The prepared magnetically recyclable core-shell hydrogel microspheres have a particle size of 170-180 μm and a Fe3O4 loading of 12-15 wt%.

2. The use of the magnetically recyclable core-shell hydrogel microspheres according to claim 1 in the adsorption and separation of buffalo milk lactose, characterized in that: In step S1, FeCl3·6H2O and FeCl2·4H2O are dissolved in deionized water in a molar ratio of 1.8:1-2.2:1, and ammonia water is added dropwise to a pH of 9.5-11.5 under nitrogen protection, and the mixture is reacted at 75-85°C for 0.8-1.2 h to obtain Fe3O4 nanoparticles; then a mixed solution of ethyl orthosilicate and ethanol in a volume ratio of 1:8-1:12 is added, and the mixture is reacted at 45-55°C for 5-7 h under the catalysis of ammonia water, and SiO2-coated Fe3O4 magnetic nanoparticles are obtained after magnetic separation and ethanol washing.

3. The use of the magnetically recyclable core-shell hydrogel microspheres according to claim 2 in the adsorption and separation of buffalo milk lactose, characterized in that: The amount of ethyl orthosilicate added is 18-22% of the mass of Fe3O4 nanoparticles, the magnetic separation intensity after the reaction is 0.4-0.6 T, and the number of ethanol washings is ≥3 times; in the prepared SiO2-coated Fe3O4 magnetic nanoparticles, the Fe3O4 particle size is controlled to be 40-60 nm, and the SiO2 shell thickness is 6-10 nm.

4. The use of the magnetically recyclable core-shell hydrogel microspheres according to claim 1 in the adsorption and separation of buffalo milk lactose, characterized in that: The molar ratio of chitosan to 4-carboxylphenylboronic acid is 1:1.0-1.4; the molar ratio of coupling agent is EDC to NHS is 1:1.3-1.7; the grafting rate of phenylboronic acid grafted chitosan obtained is ≥12%.

5. Use of the magnetically recyclable core-shell hydrogel microspheres according to claim 4 in the adsorption and separation of buffalo milk lactose, characterized in that: The pH of the grafting reaction system is controlled at 4.8-5.7, and the dialysis cut-off molecular weight is 3.0-4.0 kDa; the grafting rate of the obtained phenylboronic acid grafted chitosan is 16-20%, and the product intrinsic viscosity is 110-160 mL / g.

6. The use of the magnetically recyclable core-shell hydrogel microspheres according to claim 1 in the adsorption and separation of buffalo milk lactose, characterized in that: The magnetically recoverable core-shell hydrogel microspheres were mixed with buffalo milk at pH 6.8-7.7 at a solid-liquid ratio of 1:35-45 g / mL at room temperature, magnetically stirred at 140-160 rpm for adsorption for 20-30 min, and the core-shell hydrogel microspheres were recovered within 2-4 min under a 0.3-0.5 T magnetic field, with a lactose adsorption rate of ≥80% and a milk protein retention rate of >90%. The recovered core-shell hydrogel microspheres were immersed in a citric acid buffer at pH 3.3-3.7 containing 0.25-0.35 M NaCl, and the lactose was fully shaken to desorb. The microspheres were rinsed with deionized water and reused.

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