Alpha-amylase immobilization method based on magnetic MEPCM and ZIFs

Abstract

The invention discloses an alpha-amylase immobilization method based on magnetic MEPCM and ZIFs. The alpha-amylase immobilization method comprises the following steps: S1, preparing the magnetic MEPCM; s2, preparing a microporous magnetic MEPCM (at) ZIF; s3, mesoporous magnetic MEPCM coated HZIF is prepared; s4, preparing MEPCM (at) HZIF / NH2; and S5, preparing the immobilized alpha-amylase MEPCM (at) HZIF / Amy. In order to solve the problems that a traditional carrier immobilized enzyme is narrow in use working temperature range, poor in storage stability, thermal stability and cycling stability and difficult to recycle, the invention provides an immobilized enzyme which can be recycled for multiple times and takes a temperature control type phase change material microcapsule as a carrier material and a preparation method of the immobilized enzyme. The stability and activity of the immobilized enzyme can be remarkably improved by utilizing the characteristic of the function of adjusting the microenvironment temperature of the carrier material, and the carrier material has great application potential in the field of development and application of the immobilized enzyme.

Description

Technical field

[0001] The present invention relates to the field of immobilization of α-amylase. More specifically, the present invention relates to a method for immobilizing α-amylase based on magnetic MEPCM and ZIFs. Background art

[0002] α-Amylase (α-Amy) is a bioenzyme that can hydrolyze starch molecules. It endogenously degrades the α-1,4-d-glycosidic bond between glucose residues in starch molecules and other similar α-glucans, thereby releasing glucose, short-chain oligosaccharides, limit dextrins, maltotriose, and maltose. Therefore, this enzyme is widely used in industries such as food processing, grain industry, alcohol industry, and fermentation industry. Generally, in starch-related industries, α-Amy is mainly used for starch saccharification and liquefaction to produce modified starches and starch sugars such as glucose and high fructose corn syrup. In the beer industry, the addition of α-Amy makes the starch liquefy faster, significantly improving the liquor yield; the hydrolysis products replace part of the malt, increasing the adjuvant. The application of α-Amy in various industries can reduce the production cycle and also save food resources. However, free enzymes have significant disadvantages: their structure is easily affected by the external environment and leads to inactivation; they are difficult to separate and recycle and are difficult to use continuously. The emergence of immobilized enzyme technology overcomes the above disadvantages of free enzymes, making the optimal reaction temperature range of immobilized enzymes smaller, greatly promoting the application and development of enzyme engineering. Traditional methods for immobilizing enzymes include: entrapment method, adsorption method, covalent bond and crosslinking method. The selection of the carrier also plays a crucial role in enzyme immobilization. Generally, the requirements for the carrier are as follows: good mechanical properties, large specific surface area, cheap and easily available, etc. Traditional carrier materials include: inorganic carrier materials, organic carrier materials, composite materials, etc. Among them, metal-organic framework materials (MOFs) have received extensive attention as immobilization carriers due to their unique structure and physical and chemical properties. Zeolitic imidazolate frameworks (ZIFs) are typical representatives of them. This type of porous crystalline material combines the dual advantages of MOF and zeolite, having ultra-high surface area, porous, high crystallinity, multi-functionalization, and excellent thermal and chemical stability and other characteristics. However, the immobilization carrier only plays a role in carrying and fixing the enzyme, and the storage stability, thermal stability, and recycling stability of the enzyme can be improved through the action of the carrier. However, the currently disclosed MOF-based enzyme carriers still cannot overcome the disadvantages of narrow temperature range for enzyme-catalyzed reactions and small optimal reaction temperature range.

[0003] Therefore, in order to expand the application of immobilized enzymes in the field of industrial production, it is urgent to develop a new type of carrier material with automatic microenvironment temperature regulation to immobilize enzymes, thereby solving the above defects.

[0004] In recent years, the issues of sustainable development and the utilization of renewable energy have become the focus of people's attention. As a latent heat storage material, phase change materials can store and release energy through phase changes and have temperature regulation functions. However, due to the problem of volume change during the phase change process, their application scope is greatly limited. Microencapsulated phase change materials (MEPCM) refer to composite phase change materials with a "core-shell" structure constructed by using microencapsulation technology to coat a layer of organic or inorganic wall materials with certain mechanical strength and stable performance on the surface of the phase change materials. Microencapsulated phase change materials not only have the temperature regulation function of phase change materials but also can effectively isolate the phase change materials from the outside, eliminating problems such as leakage and loss during the phase change of phase change materials. The wall materials used for microencapsulated phase change materials include organic materials and inorganic materials. Organic wall materials have disadvantages such as flammability, poor strength, and slow thermal response. The phase change microcapsules prepared with inorganic wall materials can control the ambient temperature around the microcapsules within a certain range by storing and releasing energy, thus having a certain temperature control effect on the microenvironment. Therefore, if microencapsulated phase change materials are used as carriers to immobilize enzymes, the disadvantage of the narrow optimal temperature range of enzymes can be effectively solved. Summary of the Invention

[0005] In order to solve the problems of the narrow working temperature range, poor storage stability, thermal stability, and recycling stability, and difficulty in recycling of traditional carrier-immobilized enzymes, the present invention provides an immobilized enzyme with a temperature-controlled phase change material microcapsule as the carrier material that can be recycled multiple times and its preparation method. By utilizing the characteristic of the carrier material having the function of adjusting the microenvironment temperature, the stability and activity of the immobilized enzyme can be significantly improved, and it has great application potential in the development and application fields of immobilized enzymes.

[0006] In order to achieve these and other advantages according to the present invention, an α-amylase immobilization method based on magnetic MEPCM and ZIFs is provided, including the following steps:

[0007] S1. Prepare magnetic MEPCM;

[0008] S2. Disperse the MEPCM prepared in S1 in a 2-methylimidazole solution, then perform ultrasonic treatment, and then add a metal ion solution. After stirring evenly, microporous magnetic MEPCM@ZIF is obtained, and the obtained microporous magnetic MEPCM@ZIF is centrifuged, washed, and recovered with methanol, and then dried in vacuum for standby;

[0009] S3. Disperse the microporous magnetic MEPCM@ZIF prepared in S2 in a methanol solution, add an equal mass of NaAuCl4 thereto, and stir vigorously for ion exchange to obtain mesoporous magnetic MEPCM@HZIF, and the obtained mesoporous magnetic MEPCM@HZIF is centrifuged, washed, and recovered with methanol, and then dried in vacuum for standby;

[0010] S4. Place the mesoporous magnetic MEPCM@HZIF prepared in S3 into a methanol solution for amination. After stirring evenly, MEPCM@HZIF / NH2 is obtained, and the obtained MEPCM@HZIF / NH2 is centrifuged, washed and recovered with methanol, and then dried in vacuum for later use;

[0011] S5. Disperse the MEPCM@HZIF / NH2 prepared in S4 in a crosslinking agent for incubation and activation, and then wash it several times with deionized water until the crosslinking agent is completely washed away to obtain the magnetic phase change microcapsules activated by the crosslinking agent. Then, add α-amylase solution and stir evenly to obtain immobilized α-amylase MEPCM@HZIF / Amy. Finally, fix the immobilized α-amylase MEPCM@HZIF / Amy, and the obtained product is recovered by a magnet and stored by vacuum freeze-drying.

[0012] Preferably, in the method for immobilizing α-amylase based on magnetic MEPCM and ZIFs, the method for preparing magnetic MEPCM in S1 specifically includes:

[0013] S1.1. Stir the phase change energy storage material and the silicon source evenly at a mass ratio of 1:1 under the condition of 50 °C for later use;

[0014] S1.2. Mechanically stir the non-aqueous suspension mixed with the surfactant and magnetic nanoparticles at 50 °C to form a dispersion for later use;

[0015] S1.3. After mixing the solutions prepared in S1.1 and S1.2, ultrasonically stir until a uniform magnetic emulsion is obtained. Then, add hydrochloric acid solution to the obtained magnetic emulsion, stir evenly and perform aging treatment, and then wash and filter several times with deionized water and dry to obtain magnetic MEPCM.

[0016] Preferably, in the method for immobilizing α-amylase based on magnetic MEPCM and ZIFs, the phase change energy storage material in S1.1 is any one or a combination of several of higher aliphatic hydrocarbons, and higher aliphatic alcohols, acids, and esters organic phase change energy storage materials.

[0017] Preferably, in the method for immobilizing α-amylase based on magnetic MEPCM and ZIFs, the silicon source in S1.1 is any one of sodium silicate, potassium silicate, tetraethyl orthosilicate, or methyltrimethoxysilane.

[0018] Preferably, in the method for immobilizing α-amylase based on magnetic MEPCM and ZIFs, the magnetic nanoparticles in S1.2 are any one of Co3O4 nanoparticles, Fe2O3 nanoparticles, or Fe3O4 nanoparticles.

[0019] Preferably, in the method for immobilizing α-amylase based on magnetic MEPCM and ZIFs, the non-aqueous suspension in S1.2 is one of formamide, acetonitrile or methanol.

[0020] Preferably, in the method for immobilizing α-amylase based on magnetic MEPCM and ZIFs, the metal ion solution added in S2 is Co 2+ solution or Zn 2+ solution.

[0021] Preferably, in the method for immobilizing α-amylase based on magnetic MEPCM and ZIFs, the amidation reagent used for amidation treatment in S4 is any one of 3-mercaptopropionyl hydrazide, β-mercaptoethylamine, mercapto-PEG amine or 3-mercaptopropyl-N-hydroxysuccinimide ester.

[0022] Preferably, in the method for immobilizing α-amylase based on magnetic MEPCM and ZIFs, the cross-linking agent in S5 is any one of formaldehyde, 4-toluenesulfonyl chloride or glutaraldehyde.

[0023] Preferably, in the method for immobilizing α-amylase based on magnetic MEPCM and ZIFs, when immobilizing the immobilized α-amylase MEPCM@HZIF / Amy in S5, the mass ratio of MEPCM@HZIF / NH2 to α-amylase used is 2:1 - 5.

[0024] The beneficial effects of the present invention are as follows:

[0025] 1. The present invention uses magnetic phase change microcapsules and mesoporous zeolitic imidazolate frameworks crystals as loading materials, which have strong magnetism and can be recycled in the environment; the phase change microcapsules can automatically adjust to relieve temperature, broaden the optimal temperature range of the enzyme; and the mesoporous zeolitic imidazolate frameworks crystals have porosity, which can provide a microenvironment for the enzyme reaction, enhance the contact between the enzyme and the substrate and increase the reaction activity.

[0026] 2. The present invention uses the covalent cross-linking method to immobilize α-amylase, with good immobilization effect, less enzyme loss and can be reused.

[0027] Other advantages, objectives and features of the present invention will be partially reflected by the following description, and partially will be understood by those skilled in the art through the research and practice of the present invention. Description of the Drawings

[0028] Figure 1 It is the morphology structure diagram of the mesoporous zeolitic imidazolate framework (ZIF) magnetic phase change microcapsule in the embodiment of the present invention;

[0029] Figure 2This is the pH stability control chart of free α-amylase and immobilized α-amylase in the embodiments of the present invention;

[0030] Figure 3 This is the temperature stability control chart of free α-amylase and immobilized α-amylase in the embodiments of the present invention;

[0031] Figure 4 This is the graph of the number of cycles and residual activity of immobilized α-amylase in the embodiments of the present invention;

[0032] Figure 5 This is the thermal cycling curve of docosane and magnetic phase change microcapsules in the embodiments of the present invention;

[0033] Figure 6 This is the magnetic property analysis graph of magnetic phase change microcapsules in the embodiments of the present invention. Detailed implementation manners

[0034] The following further describes the present invention in detail with reference to the drawings, so that those skilled in the art can implement it according to the description in the specification.

[0035] It should be noted that the experimental methods described in the following implementation schemes are all conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial channels unless otherwise specified.

[0036] As Figures 1 - 6 shown, the embodiments of the present invention provide an α-amylase immobilization method based on magnetic MEPCM and ZIFs, which covalently cross-links α-amylase on the modified phase change microcapsules, and specifically includes the following steps:

[0037] S1. Preparation of magnetic MEPCM:

[0038] Mix docosane and tetraethyl orthosilicate with a mass ratio of 1:1 and stir evenly at 50°C. At the same time, mechanically stir a non-aqueous suspension containing 3.0 g of CTAB and 1.20 g of Fe3O4 magnetic nanoparticles at 50°C to form a dispersion; mix the above two liquids and obtain a stable and uniform magnetic emulsion under the action of ultrasonic stirring. Then, dropwise add a hydrochloric acid solution with a concentration of 1.78 mol / L, turn off the stirrer after stirring for 3 h, age for 24 h, wash with deionized water and filter several times, and then dry to obtain magnetic phase change microcapsules.

[0039] S2. Preparation of microporous MEPCM@ZIF-8:

[0040] Disperse the MEPCM prepared in S1 in a 2-methylimidazole solution (0.82 g, 26 mL), and ultrasonicate the mixture for 30 min. After the ultrasonication, quickly add 10 mL of a 30 mM Zn(NO3)2·6H2O solution to the solution, and stir at room temperature for 60 min to obtain microporous magnetic MEPCM@ZIF-8. Wash the obtained MEPCM@ZIF-8 three times by centrifugation with methanol and recover it. After vacuum drying, it is reserved for use.

[0041] S3. Preparation of mesoporous magnetic MEPCM@HZIF-8:

[0042] Disperse the MEPCM@ZIF-8 prepared in S2 in an appropriate amount of methanol solution, add an equal mass of NaAuCl4, and stir vigorously for ion exchange. Stir the mixture for 12 h. Wash the obtained MEPCM@HZIF-8 three times by centrifugation with methanol and recover it. After vacuum drying, it is reserved for use.

[0043] S4. Amination of MEPCM@HZIF-8:

[0044] Disperse the MEPCM@HZIF-8 obtained in S3 and an equal mass of β-mercaptoethylamine in an appropriate amount of methanol solution, and stir the mixture for 12 h. Wash the obtained MEPCM@HZIF-8 / NH2 three times by centrifugation with methanol and recover it. After vacuum drying, it is reserved for use.

[0045] S5. Preparation of immobilized α-amylase MEPCM@HZIF-8 / Amy:

[0046] Disperse the aminated MEPCM@HZIF-8 / NH2 obtained in S4 in a 5% glutaraldehyde solution by volume ratio, incubate and activate for 90 min, then wash it several times with deionized water until the glutaraldehyde is completely washed away to obtain a magnetic phase change microcapsule activated by glutaraldehyde. Then add a certain concentration of α-amylase solution and stir at room temperature for several hours to obtain immobilized α-amylase MEPCM@HZIF-8 / Amy (MEPHA). Select a suitable immobilization method according to the α-amylase loading amount. The product is recovered by a magnet and vacuum freeze-dried for later use.

[0047] Among them, the measurement method of the immobilized enzyme loading amount is as follows:

[0048] Centrifuge the immobilized enzyme mixture obtained in S5 at 4 °C and 8000 rpm for 10 min, and take the supernatant as the test solution. Determine the amount of the immobilized enzyme by the Coomassie Brilliant Blue method. This method measures the optical adsorption of the supernatant (free enzyme) at 595 nm, and calculates the amount of the enzyme using bovine serum albumin as the standard. The immobilization efficiency of α-amylase is calculated by the following formula:

[0049]

[0050] In addition, the enzyme activity was also measured in this example:

[0051] Take 1 mL (10 mg / mL) of soluble starch preheated at 60 °C (dissolved in citrate-sodium dihydrogen phosphate buffer, 50 mM, pH 6), add 1 mg of immobilized enzyme and react at 60 °C for 10 min. Immediately take 100 μL of the reaction solution and add it to a stoppered colorimetric tube containing 1 mL of DNS. Heat it in a water bath at 100 °C for 5 min and then quickly cool it. Measure the absorbance after 15 min. The standard curve for measuring reducing sugars by the 3,5-dinitrosalicylic acid method is as follows:

[0052] A = 5.1029x + 0.0005, R 2 = 0.9962

[0053] where x is in the unit of mg / mL.

[0054] The calculation formula for the activity of α-amylase is as follows:

[0055]

[0056] where ΔA represents the increment of absorbance, N represents the dilution factor when measuring the absorbance, and T represents the reaction time (min).

[0057] For the immobilized α-amylase prepared in Example 1, its morphological structure was characterized and its stability, including pH stability, temperature stability, operation stability, and phase transition performance, was tested. The steps and results are as follows:

[0058] 1. Morphological structure of the immobilized enzyme:

[0059] We used SEM to characterize the morphological structure of the immobilized enzyme carrier MEPCM@HZIF-8, and the results are as Figure 1 shown. It can be seen from Figure 1 that the mesoporous magnetic MEPCM@HZIF-8 presents a good spherical shape with a relatively smooth surface, and pores can be observed on its surface, indicating the successful synthesis of MEPCM@HZIF-8.

[0060] 2. pH stability:

[0061] During the determination of the activities of free α-amylase and immobilized α-amylase, six soluble starch substrates with different pH values (4.5, 5, 6, 6.5, 7, 8) and a concentration of 10 mg / mL were prepared by dissolving soluble starch in citrate-disodium hydrogen phosphate buffer. Based on this, the optimal pH of α-amylase was determined. The specific method is as follows: Take 0.5 U of free enzyme or 1 mg of MEPHA in a 1.5 mL centrifuge tube. At the same temperature, add 1 mL of 10 mg / mL soluble starch and shake for 5 - 10 s to mix the enzyme and substrate evenly, and incubate for 10 min. Then, take 100 μL of the reaction solution and add it to a 10 mL stoppered colorimetric tube containing 1 mL of DNS solution. After boiling water bath for 5 min, add deionized water to make up the volume to 10 mL. Shake well and cool at room temperature for 10 min, then take 300 μL and add it to a micro quartz cuvette, and measure the absorbance at 540 nm. The control group was to take 100 μL of soluble starch and add it to a 10 mL stoppered colorimetric tube containing 1 mL of DNS solution, and the other steps were the same as those for measuring the absorbance when adding the enzyme. Calculate the enzyme activity with the content of the product reducing sugar, and take the ratio of the enzyme activity at different pH gradients to the highest enzyme activity as the relative enzyme activity, expressed as a percentage. The results are as Figure 2 shown.

[0062] It can be Figure 2 seen that the optimal pH of the immobilized α-amylase based on magnetic composite phase change microcapsules is 6.5, and its activity is better than that of the free enzyme in an alkaline environment; pH 6 and 6.5 were respectively selected as the optimal pH values for the activities of free α-amylase and immobilized α-amylase.

[0063] 3. Temperature stability:

[0064] During the activity detection of free α-amylase and immobilized α-amylase, the enzyme activity at different temperature gradients was measured by changing the reaction temperature to obtain the optimal temperature of α-amylase. The temperature gradients were set as 30, 40, 50, 60, 70, 80 °C. The specific method is as follows: Take 0.5 U of free enzyme or 1 mg of MEPHA in a 1.5 mL centrifuge tube, add 1 mL of 10 mg / mL soluble starch solution with the optimal pH measured in step (1), shake for 5 - 10 seconds to mix the enzyme and substrate evenly, react for 10 min at different incubation temperatures, then take 100 μL of the reaction solution and add it to a 10 mL stoppered colorimetric tube containing 1 mL of DNS solution, boil in a water bath for 5 min, then add deionized water to make up the volume to 10 mL. After shaking well and cooling at room temperature for 10 min, take 300 μL and add it to a micro quartz cuvette, and measure the absorbance at 540 nm. The control group is deionized water. Take 100 μL of deionized water and add it to a 10 mL stoppered colorimetric tube containing 1 mL of DNS solution, and the other steps are the same as those for measuring the absorbance after adding the soluble starch solution. Calculate the enzyme activity based on the content of the product reducing sugar, and take the ratio of the enzyme activity at different temperature gradients to the highest enzyme activity as the relative enzyme activity, expressed as a percentage. The results are as Figure 3 shown.

[0065] As Figure 3 can be seen, the temperature of 50 °C was selected as the optimal temperature for the activities of free α-amylase and immobilized α-amylase.

[0066] 4. Operational stability

[0067] After measuring the activity of MEPHA, adsorb it on the outer side of the centrifuge tube with a magnet, then pour out the reaction substrate, and then wash it 3 times with deionized water. According to the optimal temperature of the immobilized α-amylase in step (2), continue to measure the activity of the recycled immobilized α-amylase according to the method of measuring the activity in step (2) in a cycle. Repeat this cycle ten times. Take the ratio of the enzyme activity measured each time to the enzyme activity of the first time as the relative enzyme activity, expressed as a percentage. The results are as Figure 4 shown.

[0068] As Figure 4 can be seen, the enzyme activity decreased relatively smoothly in the first three times. Even until the fourth time, it could still maintain about 75%. From the fifth time to the ninth time, it still remained at about 50%. This indicates that the immobilized α-amylase based on magnetic phase change microcapsules can be stably used about nine times.

[0069] 5. Phase change performance

[0070] The phase change performance of magnetic MEPCM and n-docosane was characterized by DSC, and the results are as Figure 5 shown. Therefore, during the cooling process, pure n-docosane showed two crystallization peaks at 36.19 °C during the cooling process

[0071] (The phase transition temperature T R ) and 33.30 °C (the crystallization temperature T C ). The appearance of T R is due to the existence of a metastable transition phase during the phase transition of solid paraffin such as n-docosane from the liquid phase to the crystalline phase. During the heating process, there is only one melting peak (the melting temperature T m ), and the peak position is at 48.47 °C because n-docosane directly transforms from the anisotropic crystalline phase to the isotropic liquid phase. The phase change performance of the core material of the magnetic MEPCM also has a similar change trend. However, due to the influence of the Fe3O4 / SiO2 composite wall material, its T R , T C and T m all shift to lower positions, being 36.6 °C, 32.2 °C and 48.83 °C respectively.

[0072] This crystallization enthalpy (ΔH C ) and melting enthalpy (ΔH m ) are important parameters characterizing the heat storage capacity of PCMs. As Figure 5 shows, the ΔH C and ΔH m of pure n-docosane are both higher than 210 J / g, indicating that pure n-docosane has excellent energy storage and release capabilities. The ΔH C and ΔH m of the magnetic MEPCM are 100.6 J / g and 102.5 J / g respectively, which are significantly lower than those of pure n-docosane, but it does not affect the energy storage and release of MEPCM.

[0073] The magnetic field strength is an important indicator for testing the magnetism of immobilized enzymes and whether they can be conveniently and quickly recovered by an external magnetic field. The magnetic strength of MEPHA in the range of -10000 Oe to +10000 Oe was analyzed using a vibrating sample magnetometer (VSM). The results are as Figure 6 shows, and the saturation magnetization intensity of MEPHA is 1.48 emu / g.

[0074] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the embodiments shown and described here.

Claims

1. A method for immobilizing α-amylase based on magnetic MEPCM and ZIFs, characterized in that, It includes the following steps: S1. Prepare magnetic MEPCM; S2. Disperse the MEPCM prepared in S1 in a 2-methylimidazole solution, then perform ultrasonic treatment, and then add a metal ion solution. After stirring evenly, microporous magnetic MEPCM@ZIF is obtained. Use methanol to centrifuge, wash and recover the obtained microporous magnetic MEPCM@ZIF, and set it aside after vacuum drying; S3. Disperse the microporous magnetic MEPCM@ZIF prepared in S2 in a methanol solution, add NaAuCl4 of the same mass as it, and stir vigorously for ion exchange to obtain mesoporous magnetic MEPCM@HZIF. Use methanol to centrifuge, wash and recover the obtained mesoporous magnetic MEPCM@HZIF, and set it aside after vacuum drying; S4. Place the mesoporous magnetic MEPCM@HZIF prepared in S3 in a methanol solution for amination. After stirring evenly, MEPCM@HZIF / NH2 is obtained. Use methanol to centrifuge, wash and recover the obtained MEPCM@HZIF / NH2, and set it aside after vacuum drying; S5. Disperse the MEPCM@HZIF / NH2 prepared in S4 in a crosslinking agent for incubation and activation, then wash it several times with deionized water until the crosslinking agent is washed clean to obtain a magnetic phase change microcapsule activated by the crosslinking agent. Then add an α-amylase solution, stir evenly to obtain immobilized α-amylase MEPCM@HZIF / Amy. Finally, fix the immobilized α-amylase MEPCM@HZIF / Amy. The obtained product is recovered by a magnet and stored after vacuum freeze-drying.

2. The α - amylase immobilization method based on magnetic MEPCM and ZIFs according to claim 1, characterized in that, The method for preparing magnetic MEPCM in S1 specifically includes: S1.

1. Stir a phase change energy storage material and a silicon source evenly at a mass ratio of 1:1 under the condition of 50 °C for standby; S1.

2. Mechanically stir a non-aqueous suspension mixed with a surfactant and magnetic nanoparticles at 50 °C to form a dispersion for standby; S1.

3. After mixing the solutions prepared in S1.1 and S1.2, ultrasonically stir until a uniform magnetic emulsion is obtained. Drop a hydrochloric acid solution into the obtained magnetic emulsion, stir evenly, then perform aging treatment, and then wash and filter several times with deionized water and dry to obtain magnetic MEPCM.

3. The α - amylase immobilization method based on magnetic MEPCM and ZIFs according to claim 2, characterized in that, The phase change energy storage material in S1.1 is any one or a combination of several of higher aliphatic hydrocarbons and organic phase change energy storage materials such as higher aliphatic alcohols, acids, and esters.

4. The α-amylase immobilization method based on magnetic MEPCM and ZIFs according to claim 2, characterized in that, The silicon source in S1.1 is any one of sodium silicate, potassium silicate, tetraethyl orthosilicate, or methyltrimethoxysilane.

5. The α-amylase immobilization method based on magnetic MEPCM and ZIFs according to claim 2, wherein The magnetic nanoparticles in S1.2 are any one of Co3O4 nanoparticles, Fe2O3 nanoparticles, or Fe3O4 nanoparticles.

6. The immobilization method of α-amylase based on magnetic MEPCM and ZIFs according to claim 2, characterized in that, The non-aqueous suspension in S1.2 is one of formamide, acetonitrile, or methanol.

7. The α - amylase immobilization method based on magnetic MEPCM and ZIFs according to claim 1, characterized in that, The metal ion solution added in S2 is Co 2+ solution or Zn 2+ solution.

8. A method for immobilizing α-amylase based on magnetic MEPCM and ZIFs according to claim 1, characterized in that, The amination reagent used for amination treatment in S4 is any one of 3-mercaptopropionyl hydrazide, β-mercaptoethylamine, mercapto-PEG amine, or 3-mercaptopropyl-N-hydroxysuccinimide ester.

9. The α - amylase immobilization method based on magnetic MEPCM and ZIFs according to claim 1, wherein, The crosslinking agent in S5 is any one of formaldehyde, 4-toluenesulfonyl chloride, or glutaraldehyde.

10. A method for immobilizing α-amylase based on magnetic MEPCM and ZIFs as described in claim 1, characterized in that, When immobilizing the immobilized α-amylase MEPCM@HZIF / Amy in S5, the mass ratio of MEPCM@HZIF / NH2 to α-amylase used is 2:1 - 5.

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