Process for the production of xylanase preparations
By preparing a three-dimensional macroporous composite carrier and combining it with a dopamine coating and a silica protective layer, the problems of poor stability and mechanical properties of immobilized enzyme carrier materials were solved, and the high efficiency, stability and enzyme activity of xylanase preparations were improved.
Patent Information
- Application Number
- CN202610638609.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-05-11
- Publication Date
- 2026-07-10
AI Technical Summary
The carrier materials used for immobilized enzymes in existing technologies result in poor mechanical properties and stability of the enzymes, making it difficult to meet the requirements for efficient use.
A three-dimensional macroporous composite carrier was prepared by combining carbon dioxide and polyurethane. The porous structure was formed by the coordination reaction of chitosan and copper salt, and magnetic separation was carried out by adding iron oxide. Combined with a dopamine coating and a silica protective layer, the stability of the enzyme was improved.
It improves the stability and enzyme activity of xylanase preparations, enabling them to maintain high performance even after multiple uses.
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Abstract
Description
Technical Field
[0001] This application relates to the field of bioenzyme technology, and in particular to a method for producing xylanase preparations. Background Technology
[0002] Xylanases are a class of enzymes that degrade β-1,4-xylan to produce xylose. These enzymes can also degrade hemicellulose, a major component of cell walls. Therefore, they play a crucial role in the process of microbial degradation of plant cell walls to generate usable nutrients. Xylanases are typically secreted by fungi, bacteria, yeast, and algae. Commercially available xylanases are mainly produced by fermentation of filamentous fungi. Currently, the application of xylanases in feed is becoming increasingly mature and is widely used in livestock and poultry feed.
[0003] Enzyme immobilization involves binding enzyme molecules onto a carrier using physical or chemical methods. This preserves the enzyme's natural activity while facilitating separation from the reaction solution, allowing for repeated use. Immobilized enzymes exhibit high activity, stability, and are reusable, resistant to certain strengths of acids, alkalis, heat, and organic solvents. As a component of the immobilized enzyme, the carrier material significantly influences its various properties. However, current immobilized enzyme technologies often exhibit poor mechanical properties and stability. Summary of the Invention
[0004] This application is made in view of the above-mentioned problems, and its purpose is to provide a method for producing xylanase preparations, wherein the xylanase preparations obtained by the method have good stability.
[0005] Specifically, this application provides a method for producing xylanase preparations, including the following steps: S1. The xylanase, complex carrier and buffer are mixed to prepare the first mixture; S2. Mix the first mixture, the polypeptide, and the organosilane to prepare a xylanase preparation; The method for preparing the composite carrier includes the following steps: S01. Polyurethane, carbon fiber oxide and solvent are mixed, and the solid phase is collected to obtain the first precursor; The second precursor was obtained by mixing chitosan solution and copper salt, then adding porogen, emulsifier and crosslinking agent to crosslink the mixture. The third precursor is prepared by mixing the second precursor, ferrous salt, ferric salt and water; The third precursor was mixed with an EDTA salt solution, eluted, and freeze-dried to obtain the fourth precursor. S02. Mix the first precursor, the fourth precursor, dopamine hydrochloride and ethanol solution, collect the solid phase, dry it, and obtain the composite carrier.
[0006] According to one of the technical solutions in this application, at least the following beneficial effects are achieved: This application describes the ultrasonic composite of oxidized carbon fiber and polyurethane to prepare a first precursor. The first precursor has a three-dimensional macroporous structure and good mechanical strength, providing a macroscopic framework for the subsequent assembly of the composite carrier.
[0007] In this application, chitosan is coordinated with copper salt, and copper salt acts as a template to interact with relevant groups on the chitosan molecular chain; then a porogen, emulsifier and crosslinking agent are added to prepare a second precursor by emulsification and crosslinking method, in which a porous structure is formed; Ferrous and ferric salts are then added to the second precursor to generate iron(III) oxide, which is beneficial for the magnetic separation of xylanase preparations. Finally, the copper salt is removed by elution with EDTA salt solution, and the fourth precursor is obtained by freeze-drying.
[0008] Based on this, the first precursor, the fourth precursor and dopamine hydrochloride are mixed in an ethanol solution, and a polydopamine coating is formed by the self-polymerization reaction of dopamine under alkaline conditions. This coating has strong adhesion and firmly anchors the fourth precursor to the inner surface of the pores of the first precursor. After solid-liquid separation and drying, a composite carrier is obtained.
[0009] After pre-immobilization by mixing the composite carrier with xylanase, peptides and organosilanes are further added. A silica protective layer is formed in situ on the surface of the pre-immobilized enzyme, thereby improving the stability of the xylanase preparation.
[0010] According to some embodiments of this application, step S1 includes the following steps: Xylanase and phosphate buffer were mixed to prepare a xylanase mixture; The composite carrier and phosphate buffer were mixed to prepare the composite carrier mixture. After mixing the xylanase mixture and the composite carrier mixture, glutaraldehyde was added, and the solid phase was collected to obtain the first mixture.
[0011] According to some embodiments of this application, the enzyme activity of the xylanase is 1000 U / g to 20000 U / g.
[0012] According to some embodiments of this application, the pH of the phosphate buffer is 5 to 5.8.
[0013] According to some embodiments of this application, the mass concentration of the xylanase mixture is 1 g / L to 2 g / L.
[0014] According to some embodiments of this application, the mass concentration of the composite carrier mixture is 1 g / L to 2 g / L.
[0015] According to some embodiments of this application, the mass ratio of xylanase to the composite carrier is 2~4:100.
[0016] According to some embodiments of this application, after adding glutaraldehyde, the reaction is carried out at 0℃~10℃ for 12h~24h.
[0017] According to some embodiments of this application, the mass concentration of glutaraldehyde is 0.3% to 0.6%.
[0018] According to some embodiments of this application, the polypeptide described in step S2 is poly-L-lysine.
[0019] According to some embodiments of this application, the molecular weight of the poly-L-lysine is 30,000 to 70,000 Da.
[0020] According to some embodiments of this application, the organosilane includes tetramethoxysilane or tetraethyl orthosilicate.
[0021] According to some embodiments of this application, the mass ratio of the first mixture to the polypeptide is 10:1~2.
[0022] According to some embodiments of this application, the mass ratio of the first mixture to the organosilane is 100:2~5.
[0023] According to some embodiments of this application, the pore size of the polyurethane is 0.3 mm to 0.7 mm.
[0024] According to some embodiments of this application, the method for preparing the oxidized carbon fiber includes oxidizing the carbon fiber.
[0025] According to some embodiments of this application, the mesh size of the carbon fiber is 30 mesh to 100 mesh.
[0026] According to some embodiments of this application, the oxidation treatment is performed using a nitric acid solution.
[0027] According to some embodiments of this application, the mass fraction of the nitric acid solution is 60% to 70%.
[0028] According to some embodiments of this application, the oxidation treatment temperature is 80°C to 90°C.
[0029] According to some embodiments of this application, the oxidation treatment time is 10h~12h.
[0030] According to some embodiments of this application, the mass ratio of the polyurethane to the oxidized carbon fiber is 1:0.9~1.1.
[0031] According to some embodiments of this application, the method for preparing the chitosan solution includes the following steps: Chitosan, acetic acid, and water are mixed to prepare a chitosan solution.
[0032] According to some embodiments of this application, the mass concentration of the chitosan solution is 0.1 g / L to 0.5 g / L.
[0033] According to some embodiments of this application, the mass-to-volume ratio of chitosan to acetic acid is 1g~3g:2mL.
[0034] According to some embodiments of this application, the mass ratio of chitosan to copper salt is 100:0.1~2.
[0035] According to some embodiments of this application, the temperature at which the chitosan solution and copper salt are mixed is 20°C to 30°C.
[0036] According to some embodiments of this application, the chitosan solution and copper salt are mixed for 1 to 2 hours.
[0037] According to some embodiments of this application, the pore-forming agent includes paraffin and n-heptane.
[0038] According to some embodiments of this application, the crosslinking agent includes epichlorohydrin.
[0039] According to some embodiments of this application, the emulsifier includes Span-80.
[0040] According to some embodiments of this application, the volume ratio of the chitosan solution to paraffin is 100:5~10.
[0041] According to some embodiments of this application, the volume ratio of the chitosan solution to n-heptane is 100:2~5.
[0042] According to some embodiments of this application, the volume ratio of the chitosan solution to the emulsifier is 100:1~2.
[0043] According to some embodiments of this application, the volume ratio of the chitosan solution to the crosslinking agent is 100:2~4.
[0044] According to some embodiments of this application, the crosslinking temperature is 50°C to 70°C.
[0045] According to some embodiments of this application, the dispersion speed of the crosslinking is 400 rpm to 800 rpm.
[0046] According to some embodiments of this application, the crosslinking time is 3h to 4h.
[0047] According to some embodiments of this application, the second precursor is mixed with water to obtain a second precursor mixture.
[0048] According to some embodiments of this application, the mass ratio of the ferrous salt to the second precursor is 1:40~60.
[0049] According to some embodiments of this application, the molar ratio of the ferrous salt to the ferric salt is 1:1.95~2.05.
[0050] According to some embodiments of this application, the pH of the second precursor mixture, ferrous salt, and ferric salt is adjusted to 10-11 after mixing.
[0051] According to some embodiments of this application, after adjusting the pH to 10-11, the reaction is carried out at 50-70°C for 0.5-2 hours.
[0052] According to some embodiments of this application, the EDTA salt includes sodium EDTA salt.
[0053] According to some embodiments of this application, the pH of the elution is 7.5 to 8.5.
[0054] According to some embodiments of this application, the elution temperature is 20°C to 30°C.
[0055] According to some embodiments of this application, the elution time is 6h to 12h.
[0056] According to some embodiments of this application, the mass-to-volume ratio of the third precursor to the EDTA salt solution is 1g:10mL~20mL.
[0057] According to some embodiments of this application, the molar concentration of the EDTA salt solution is 0.05 mol / L to 0.2 mol / L.
[0058] According to some embodiments of this application, the mass ratio of the first precursor to dopamine hydrochloride is 2:0.5~1.5.
[0059] According to some embodiments of this application, the mass ratio of the fourth precursor to dopamine hydrochloride is 2:0.1~0.2.
[0060] According to some embodiments of this application, dopamine hydrochloride and an ethanol solution are mixed to prepare a dopamine hydrochloride solution. The first precursor and dopamine hydrochloride solution were mixed at 20℃~30℃ for 1h~2h to obtain the first precursor mixture; The mixture of the fourth precursor and the first precursor was mixed at 20℃~30℃ for 1h~2h, and the solid phase was collected. Detailed Implementation
[0061] To make the objectives, technical solutions, and advantages of this application clearer, the following description and illustration are provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.
[0062] Obviously, the following description is merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios without any inventive effort. Furthermore, it is understood that although the effort involved in such development may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, any changes to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.
[0063] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.
[0064] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).
[0065] The xylanase used in this embodiment has an enzyme activity of 10000 U / g.
[0066] Enzyme activity is defined as follows: one unit of enzyme activity is the amount of xylan produced by 1g of enzyme powder per minute at 50°C and pH 4.8 to produce 1µl of xylose. It is expressed as U / g.
[0067] The polyurethane (polyurethane foam) used in this embodiment has a size of 0.5 cm. 0.5cm 0.5cm, with an average pore size of 0.5mm.
[0068] The carbon fibers used in this application have an average diameter of 7 μm, a mesh count of 60 mesh, and an aspect ratio of 2 to 8:1.
[0069] The polypeptide used in the embodiments of this application is poly-L-lysine (CAS No. 25988-63-0), with a molecular weight of 30,000~70,000 Da.
[0070] Example 1 This embodiment describes a method for producing xylanase preparations, which consists of the following steps: S1. Mix xylanase and phosphate buffer (pH 5-5.8) to prepare xylanase mixture (1g / L). The composite carrier and phosphate buffer (pH 5-5.8) were mixed to prepare a composite carrier mixture (1 g / L). After mixing the xylanase mixture and the composite carrier mixture, glutaraldehyde was added (after adding glutaraldehyde, the mass fraction of glutaraldehyde in the mixture was 0.5%, and the reaction was carried out at 4℃ for 20 h). The solid phase was collected to obtain the first mixture. S2. Mix the first mixture with a 20% (w / w) aqueous ethanol solution; Then add the polypeptide (poly-L-lysine) and organosilane (tetramethoxysilane) and mix (treat at 25°C for 20 min), separate the solid and liquid phases, collect the solid phase, and prepare the xylanase preparation; The mass ratio of xylanase to the complex carrier is 3:100; The mass ratio of the first mixture to the polypeptide is 10:1.5; The mass ratio of the first mixture to the organosilane is 100:4.
[0071] The preparation method of the composite carrier consists of the following steps: S01. Polyurethane, carbon dioxide (mass ratio of polyurethane to carbon dioxide is 1:1) and solvent (95% ethanol aqueous solution by mass) are ultrasonically dispersed (200W) for 10 min, the solid phase is collected and vacuum dried to obtain the first precursor. Chitosan solution and copper salt (copper chloride, the mass ratio of chitosan to copper salt is 100:1) were mixed (mixed at 25°C for 2 h), and then pore-forming agent (paraffin (CAS No.: 8042-47-5) and n-heptane) and emulsifier (Span-80) were added. After adding the emulsifier, emulsification was carried out at 8000 rpm for 10 min. Then, a crosslinking agent (epoxychloroethane) was added for crosslinking (crosslinking was carried out at 60°C, dispersion speed was 600 rpm, and time was 4 h), centrifuged, washed 3 times with petroleum ether, then 3 times with isopropanol, and finally washed with water until neutral to obtain the second precursor. The second precursor was mixed with water (the mass-volume ratio of the second precursor to water was 1 g: 100 mL) to prepare the second precursor mixture; The second precursor mixture, ferrous salt (ferrous chloride, the mass ratio of ferrous chloride and the second precursor is 1:50) and ferric salt (ferric chloride, the molar ratio of ferrous chloride and ferric chloride is 1:2) were mixed and the pH was adjusted to 11 with sodium hydroxide. The mixture was then reacted at 60°C for 2 hours. The solid and liquid phases were separated, the solid phase was collected, and dried to obtain the third precursor. The third precursor and EDTA disodium solution (0.1 mol / L, the mass-to-volume ratio of the third precursor and EDTA disodium solution was 1 g: 20 mL) were mixed and eluted three times, with the EDTA disodium solution replaced after each elution. The elution temperature was 25 °C, the pH of each elution was 8, and the elution time was 10 h. The mixture was then freeze-dried (-50 °C) to obtain the fourth precursor. S02. Mix dopamine hydrochloride and a 50% (w / w) aqueous ethanol solution to prepare a dopamine hydrochloride solution (w / w) with a concentration of 2 g / L. The first precursor was immersed in a dopamine hydrochloride solution, the pH was adjusted to 10 with ammonia, and the reaction was carried out at 25°C for 2 hours; then the fourth precursor was added, and the reaction was carried out at 25°C for 2 hours. The solid and liquid phases were separated, the solid phase was collected, and vacuum dried.
[0072] The preparation method of oxidized carbon fiber consists of the following steps: Carbon fibers were mixed with a 68% nitric acid solution and oxidized at 85°C for 10 hours. After the treatment was completed, the solid phase was collected and dried under vacuum.
[0073] The method for preparing chitosan solution consists of the following steps: Chitosan (CAS No.: 9012-76-4), acetic acid (mass-volume ratio of chitosan to acetic acid is 1 g: 1 mL) and water were mixed to prepare a chitosan solution (0.2 g / L). The volume ratio of chitosan solution to paraffin is 100:10; the volume ratio of chitosan solution to n-heptane is 100:5; the volume ratio of chitosan solution to emulsifier is 100:1.5; and the volume ratio of chitosan solution to crosslinking agent is 100:3. The mass ratio of the first precursor to dopamine hydrochloride is 2:1; The mass ratio of the fourth precursor to dopamine hydrochloride is 2:0.15.
[0074] Example 2 This embodiment describes a method for producing xylanase preparations, which differs from Example 1 in that: The mass ratio of xylanase to the complex carrier is 2:100; The mass ratio of the first mixture to the polypeptide is 10:2; The mass ratio of the first mixture to the organosilane is 100:2.
[0075] The mass ratio of the first precursor to dopamine hydrochloride is 2:1.5; The mass ratio of the fourth precursor to dopamine hydrochloride is 2:0.1.
[0076] Example 3 This embodiment describes a method for producing xylanase preparations, which differs from Example 1 in that: The mass ratio of xylanase to the complex carrier is 4:100; The mass ratio of the first mixture to the polypeptide is 10:1; The mass ratio of the first mixture to the organosilane is 100:5.
[0077] The mass ratio of the first precursor to dopamine hydrochloride is 2:0.5; The mass ratio of the fourth precursor to dopamine hydrochloride is 2:0.2.
[0078] Example 4 This embodiment describes a method for producing xylanase preparations, which differs from Example 1 in that: The mass ratio of xylanase to the complex carrier is 4:100; The mass ratio of the first mixture to the polypeptide is 10:2; The mass ratio of the first mixture to the organosilane is 100:5.
[0079] The mass ratio of the first precursor to dopamine hydrochloride is 2:1.5; The mass ratio of the fourth precursor to dopamine hydrochloride is 2:0.2.
[0080] Example 5 This embodiment describes a method for producing xylanase preparations, which differs from Example 1 in that: The mass ratio of xylanase to the complex carrier is 2:100; The mass ratio of the first mixture to the polypeptide is 10:1; The mass ratio of the first mixture to the organosilane is 100:2.
[0081] The mass ratio of the first precursor to dopamine hydrochloride is 2:0.5; The mass ratio of the fourth precursor to dopamine hydrochloride is 2:0.1.
[0082] Comparative Example 1 The production method of xylanase preparation in this comparative example differs from that in Example 5 in that: Replace the oxidized carbon fiber with carbon fiber.
[0083] Comparative Example 2 The production method of xylanase preparation in this comparative example differs from that in Example 5 in that: No peptides are added.
[0084] Comparative Example 3 The production method of xylanase preparation in this comparative example differs from that in Example 5 in that: No organosilanes are added.
[0085] Comparative Example 4 The production method of xylanase preparation in this comparative example differs from that in Example 5 in that: No organosilanes or peptides are added.
[0086] The production method of xylanase preparation consists of the following steps: Xylanase and phosphate buffer (pH 5-5.8) were mixed to prepare xylanase mixture (1 g / L). The composite carrier and phosphate buffer (pH 5-5.8) were mixed to prepare a composite carrier mixture (1 g / L). After mixing the xylanase mixture and the composite carrier mixture, glutaraldehyde was added (after adding glutaraldehyde, the mass fraction of glutaraldehyde in the mixture was 0.5%, and the reaction was carried out at 4℃ for 20 h). The solid phase was collected, dried, and the xylanase preparation was obtained.
[0087] The composite carrier was prepared according to Example 5.
[0088] Comparative Example 5 The production method of xylanase preparation in this comparative example differs from that in Example 5 in that: Dopamine hydrochloride is not added.
[0089] That is, step S02 consists of the following steps: The first precursor, the fourth precursor, and a 50% aqueous ethanol solution (the mass-volume ratio of the first precursor to the aqueous ethanol solution was 1 g: 50 mL) were mixed and reacted at 25 °C for 2 h. The solid and liquid phases were separated, the solid phase was collected, and dried under vacuum.
[0090] The first and fourth precursors were prepared according to Example 5.
[0091] Relative enzyme activity is the ratio of the enzyme activity of the xylanase preparation to the initial xylanase activity.
[0092] Stability test: The enzyme activity retention rate was tested after the immobilized enzyme preparation was stored at 40°C for 30 days.
[0093] The performance test results of the examples and comparative examples are shown in Table 1.
[0094] Table 1
[0095] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.
Claims
1. A method for producing xylanase preparations, characterized in that, Includes the following steps: S1. The xylanase, complex carrier and buffer are mixed to prepare the first mixture; S2. Mix the first mixture, the polypeptide, and the organosilane to prepare a xylanase preparation; The method for preparing the composite carrier includes the following steps: S01. Polyurethane, carbon fiber oxide and solvent are mixed, and the solid phase is collected to obtain the first precursor; The second precursor was obtained by mixing chitosan solution and copper salt, then adding porogen, emulsifier and crosslinking agent to crosslink the mixture. The third precursor is prepared by mixing the second precursor, ferrous salt, ferric salt and water; The third precursor was mixed with an EDTA salt solution, eluted, and freeze-dried to obtain the fourth precursor. S02. Mix the first precursor, the fourth precursor, dopamine hydrochloride and ethanol solution, collect the solid phase, dry it, and obtain the composite carrier.
2. The production method according to claim 1, characterized in that, Step S1 includes the following steps: Xylanase and phosphate buffer were mixed to prepare a xylanase mixture; The composite carrier and phosphate buffer were mixed to prepare the composite carrier mixture. After mixing the xylanase mixture and the composite carrier mixture, glutaraldehyde was added, and the solid phase was collected to obtain the first mixture. And / or, the enzyme activity of the xylanase is 1000 U / g to 10000 U / g; And / or, the pH of the phosphate buffer is 5 to 5.8; And / or, the mass concentration of the xylanase mixture is 1 g / L to 2 g / L; And / or, the mass concentration of the composite carrier mixture is 1 g / L to 2 g / L; And / or, the mass ratio of the xylanase to the composite carrier is 2-4:100; And / or, after adding glutaraldehyde, react at 0℃~10℃ for 12h~24h; And / or, the mass concentration of the glutaraldehyde is 0.3% to 0.6%.
3. The production method according to claim 1, characterized in that, The polypeptide mentioned in step S2 is poly-L-lysine; And / or, the molecular weight of the poly-L-lysine is 30,000 to 70,000 Da. And / or, the organosilane includes tetramethoxysilane or tetraethyl orthosilicate; And / or, the mass ratio of the first mixture to the polypeptide is 10:1~2; And / or, the mass ratio of the first mixture to the organosilane is 100:2~5.
4. The production method according to claim 1, characterized in that, The polyurethane has a pore size of 0.3 mm to 0.7 mm; And / or, the method for preparing the oxidized carbon fiber includes oxidizing the carbon fiber; And / or, the mesh size of the carbon fiber is 30 mesh to 100 mesh; And / or, the oxidation treatment is an oxidation treatment using nitric acid solution; And / or, the mass fraction of the nitric acid solution is 60%~70%; And / or, the oxidation treatment temperature is 80℃~90℃; And / or, the oxidation treatment time is 10h~12h; And / or, the mass ratio of the polyurethane to the oxidized carbon fiber is 1:0.9~1.
1.
5. The production method according to claim 1, characterized in that, The method for preparing the chitosan solution includes the following steps: Chitosan, acetic acid and water were mixed to prepare a chitosan solution; And / or, the mass concentration of the chitosan solution is 0.1 g / L to 0.5 g / L; And / or, the mass-to-volume ratio of chitosan to acetic acid is 1g~3g:2mL; And / or, the mass ratio of chitosan to copper salt is 100:0.1~2; And / or, the temperature at which the chitosan solution and copper salt are mixed is 20°C to 30°C; And / or, the chitosan solution and copper salt are mixed for 1 to 2 hours.
6. The production method according to claim 1, characterized in that, The pore-forming agent includes paraffin and n-heptane; And / or, the crosslinking agent includes epichlorohydrin; And / or, the emulsifier includes Span-80; And / or, the volume ratio of the chitosan solution to paraffin is 100:5~10; And / or, the volume ratio of the chitosan solution to n-heptane is 100:2~5; And / or, the volume ratio of the chitosan solution to the emulsifier is 100:1~2; And / or, the volume ratio of the chitosan solution to the crosslinking agent is 100:2~4; And / or, the crosslinking temperature is 50°C to 70°C; And / or, the dispersion rate of the crosslinking is 400 rpm to 800 rpm; And / or, the crosslinking time is 3h~4h.
7. The production method according to claim 1, characterized in that, The second precursor is mixed with water to obtain a second precursor mixture; And / or, the mass ratio of the ferrous salt to the second precursor is 1:40~60; And / or, the molar ratio of the ferrous salt to the ferric salt is 1:1.95~2.05; And / or, the pH of the second precursor mixture, ferrous salt and ferric salt is adjusted to 10-11 after mixing; And / or, after adjusting the pH to 10-11, react at 50-70℃ for 0.5-2 hours.
8. The production method according to claim 1, characterized in that, The EDTA salt includes sodium EDTA salt; And / or, the elution pH is 7.5 to 8.5; And / or, the elution temperature is 20°C to 30°C; And / or, the elution time is 6h~12h; And / or, the mass-to-volume ratio of the third precursor to the EDTA salt solution is 1g:10mL~20mL; And / or, the molar concentration of the EDTA salt solution is 0.05 mol / L to 0.2 mol / L.
9. The production method according to claim 1, characterized in that, The mass ratio of the first precursor to dopamine hydrochloride is 2:0.5~1.5; And / or, the mass ratio of the fourth precursor to dopamine hydrochloride is 2:0.1~0.
2.
10. The production method according to claim 1, characterized in that, Dopamine hydrochloride and ethanol solution are mixed to prepare dopamine hydrochloride solution; The first precursor and dopamine hydrochloride solution were mixed at 20℃~30℃ for 1h~2h to obtain the first precursor mixture; The mixture of the fourth precursor and the first precursor was mixed at 20℃~30℃ for 1h~2h, and the solid phase was collected.