阅读说明：本技术 一种磁性载脂肪酶的光酶催化剂及其制备方法和应用 (Magnetic lipase-loaded photocatalyst and preparation method and application thereof ) 是由 叶勇 黄传庆 唐小月 于 2020-12-31 设计创作，主要内容包括：本发明公开了一种磁性载脂肪酶的光酶催化剂及其制备方法和应用,该光酶催化剂以醛基改性氨基化核-壳结构Fe-3O-4@ZnO-ZnS为载体,以脂肪酶为活性成分；所述载体以Fe-3O-4为核,醛基改性氨基化ZnO-ZnS为壳。其制备方法包括如下步骤：先以硫酸亚铁和氯化铁合成纳米Fe-3O-4核,再与醋酸锌和硫代乙酰胺反应得到核-壳结构Fe-3O-4@ZnO-ZnS载体,用3-氨基丙基-三乙氧基硅烷和戊二醛修饰,得到醛基改性氨基化核-壳结构Fe-3O-4@ZnO-ZnS载体,再加入脂肪酶,冷冻干燥获得磁性载脂肪酶光酶催化剂。该光酶催化剂用5～100W白炽灯光照10～30min,可显著提高中长链甘油三酯的产率。(The invention discloses a magnetic lipase-loaded photocatalyst, a preparation method and application thereof 3 O 4 @ ZnO-ZnS is used as a carrier, and lipase is used as an active component; the carrier is made of Fe 3 O 4 The aldehyde modified aminated ZnO-ZnS is taken as a core and a shell. The preparation method comprises the following steps: firstly, ferrous sulfate and ferric chloride are used for synthesizing nano Fe 3 O 4 Reacting with zinc acetate and thioacetamide to obtain Fe with core-shell structure 3 O 4 The @ ZnO-ZnS carrier is modified by 3-aminopropyl-triethoxysilane and glutaraldehyde to obtain aldehyde group modified aminated core-shell structure Fe 3 O 4 And (2) adding the @ ZnO-ZnS carrier into the lipase, and freeze-drying to obtain the magnetic lipase-loaded photocatalyst. The photocatalyst is irradiated by a 5-100W incandescent lamp for 10-30 min, and can remarkably improve medium-long chain glycerolYield of triesters.)

1. The magnetic lipase-supported photocatalyst is characterized in that the photocatalyst is prepared by modifying aldehyde group to aminate Fe with a core-shell structure₃O₄The @ ZnO-ZnS is taken as a carrier, lipase is taken as an active component, and the mass ratio of the carrier to the lipase is 100 (1-10); the carrier is made of Fe₃O₄The core is aldehyde group modified aminated ZnO-ZnS and the mass ratio of the core to the shell is 1 (10-100).

2. The method for preparing the magnetic lipase-supported photocatalyst as recited in claim 1, comprising the steps of:

(1) according to Fe₃O₄Dispersing in ethanol water solution, adding zinc acetate and sodium hydroxide water solution, mixing, centrifuging, separating precipitate to obtain Fe₃O₄@ ZnO; adding thioacetamide to react to obtain Fe₃O₄@ ZnO-ZnS support;

(2) subjecting said Fe to₃O₄Dispersing the @ ZnO-ZnS carrier in an ethanol water solution, adding 3-aminopropyl-triethoxysilane, reacting, filtering to obtain Fe with an aminated core-shell structure₃O₄@ ZnO-ZnS substrate; amination of core-shell structures Fe₃O₄Dispersing the @ ZnO-ZnS substrate in sodium phosphate buffer solution, adding glutaraldehyde solution, stirring, centrifuging, separating precipitate, and freeze-drying to obtain aldehyde-modified aminated core-shell structure Fe₃O₄@ ZnO-ZnS support;

(3) modifying the aldehyde group to aminate a core-shell structure Fe₃O₄The @ ZnO-ZnS carrier is dispersed in phosphoric acid buffer solution, added with lipase, stirred, centrifuged, separated from solid, and freeze-dried to obtain the magnetic lipase-loaded photocatalyst.

3. The method according to claim 2, wherein the Fe in step (1)₃O₄The mass-volume ratio of the ethanol to the ethanol water solution is 1g: 1-5 mL; the volume concentration of the ethanol water solution is 60-80%; the dosage of the zinc acetate is Fe₃O₄10-100 times of the mass; the dosage of the sodium hydroxide aqueous solution is Fe₃O₄5-50 times of the mass; the mass concentration of the sodium hydroxide aqueous solution is 20-30%; the centrifugation is carried out at 8000-20000 rpm for 15-30 min; the addition amount of the thioacetamide is Fe₃O₄@ ZnO is 1-5 times of the mass; the reaction is carried out at 60-80 ℃ for 0.5-2 h.

4. The method according to claim 3, wherein the Fe in the step (2)₃O₄The mass-volume ratio of the @ ZnO-ZnS carrier to the ethanol aqueous solution is 1g: 1-10 mL; the volume concentration of the ethanol water solution is 60-80%; of said 3-aminopropyl-triethoxysilaneThe addition amount is Fe₃O₄The mass of the @ ZnO-ZnS carrier is 1-10 times that of the carrier; the reaction is carried out for 5-6 h at 50-60 ℃; said aminated core-shell structure Fe₃O₄The mass-volume ratio of the @ ZnO-ZnS substrate to the sodium phosphate buffer solution is 1g: 10-100 mL; the pH value of the sodium phosphate buffer solution is 6.5-8; the addition amount of the glutaraldehyde solution is amination core-shell structure Fe₃O₄0.2-1 time of the mass of the @ ZnO-ZnS substrate; the mass concentration of the glutaraldehyde solution is 15-25%; the stirring is carried out at 50-500 rpm for 2-4 h, and the centrifugation is carried out at 8000-20000 rpm for 15-30 min.

5. The method according to claim 4, wherein the aldehyde group-modified aminated core-shell structure of Fe in step (3)₃O₄The mass-volume ratio of the @ ZnO-ZnS carrier to the phosphoric acid buffer solution is 1g: 1-10 mL; the pH value of the phosphoric acid buffer solution is 6.5-8; the addition amount of the lipase is aldehyde group modified aminated core-shell structure Fe₃O₄1-10% of the mass of the @ ZnO-ZnS substrate; the stirring is carried out at the temperature of 0-4 ℃ and at the rpm of 50-500 for 4-8 h, and the centrifugation is carried out at the rpm of 8000-20000 for 15-30 min.

6. The method according to claim 5, wherein the Fe is₃O₄The preparation method comprises the following steps:

dissolving ferrous sulfate and ferric chloride in water at a mass ratio of 1: 1-3 to obtain a mixed solution; heating to 80-90 ℃, adding concentrated ammonia water, uniformly mixing, centrifuging at 8000-20000 rpm for 15-30 min, separating and precipitating to obtain Fe₃O₄(ii) a The concentration of the ferrous iron in the mixed solution is 0.1-0.5M; the adding amount of the strong ammonia water is 0.25-0.5 time of the mass of iron in the mixed solution.

7. The process according to any one of claims 1 to 6, wherein the Lipase in step (3) is one or more selected from the group consisting of Lipozyme 435, Lipozyme RMIM, Lipozyme TLIM, Lipase G50 and Lipase F-AP.

8. Use of a magnetic lipase-loaded photocatalyst according to claim 1 in the preparation of long chain triglycerides.

9. Use according to claim 8, characterized in that it comprises the following steps;

two kinds of C are mixed₈～C₁₈Mixing fatty acids according to a molar ratio of 1-3: 1, mixing with glycerol, adding a magnetic lipase-loaded photocatalyst, and illuminating with a 5-100W incandescent lamp for 10-30 min to obtain medium-long chain triglyceride;

said C is₈～C₁₈The molar ratio of the fatty acid to the glycerol is 3-5: 1; the addition amount of the magnetic lipase-supported photocatalyst is C₈～C₁₈1-10% of the total mass of the fatty acid and the glycerol.

10. Use according to claim 9, wherein C is₈～C₁₈The fatty acid is two of caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid and linoleic acid.

Technical Field

The invention belongs to the field of a photocatalyst, and particularly relates to a magnetic lipase-loaded photocatalyst, and a preparation method and application thereof.

Background

Medium-and long-chain triglycerides (MLCTs) are formed by binding medium-and long-chain fatty acids to the same glycerol molecule. It exists in nature and can also be obtained by artificial hydrolysis and esterification. MLCTs are excellent sources of biologically inert energy, and are also good substances for controlling blood glucose and increasing the production of ketones in the body, thereby promoting metabolism. Due to their ability to be rapidly absorbed by the body, MLCTs can be used to control obesity and to treat various malabsorption diseases. Thus, the use of MLCTs in the development of next-generation foods and beverages has begun to be appreciated. Coconut oil, palm oil, olive oil, camphor tree oil, goat milk, butter and dairy fats all contain MLCTs, but in smaller amounts; in addition, MLCTs of natural origin also contain some long-chain fats and other compounds that are difficult to digest. Therefore, it is possible to synthesize desired MLCTs by chemical means such as esterification reaction between fatty acids and glycerol.

In the chemical synthesis of MLCTs, the biological enzyme method is more favored than the chemical method because the substrate specificity and the efficiency are higher, the operation condition is milder and is easier to control, and the by-products are fewer. However, free lipase used in the biological enzyme method is not easy to separate from a substrate, is easy to inactivate and has poor stability, so that the activity, stability and recycling of lipase can be improved after the lipase is immobilized. Chinese patent CN108285910A discloses a method for producing 1, 3-diglyceride by immobilized lipase, but the immobilized lipase will cause the decrease of enzyme activity, and the activity of lipase will decrease significantly with the increase of reaction time.

With magnetic Fe₃O₄The nano particles are used as a core, and a ZnO-ZnS heterostructure is used as a shell to form Fe with a core-shell structure₃O₄The surface of the substrate is modified with amino and aldehyde groups as fixing points to fix lipase, so that a novel photocatalyst for the photocatalyst can be formed, and the activity of the lipase is improved by light. Such studies have not been reported.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention mainly aims to provide a magnetic lipase-loaded photocatalyst.

The invention also aims to provide a preparation method of the magnetic lipase-supported photocatalyst.

The invention further aims to provide the application of the magnetic lipase-loaded photocatalyst in the preparation of medium-long chain triglyceride.

The purpose of the invention is realized by the following technical scheme.

Magnetic lipase-supported photocatalyst which is prepared by modifying aminated core-shell structure Fe with aldehyde group₃O₄The @ ZnO-ZnS is taken as a carrier, lipase is taken as an active component, and the mass ratio of the carrier to the lipase is 100 (1-10); the carrier is made of Fe₃O₄The core is aldehyde group modified aminated ZnO-ZnS and the shell is aldehyde group modified aminated ZnO-ZnS, and the mass ratio of the aldehyde group modified aminated ZnO-ZnS to the core shell is 1 (10-100).

The preparation method of the magnetic lipase-supported photocatalyst comprises the following steps:

(1) according to Fe₃O₄Dispersing in ethanol water solution, adding zinc acetate and sodium hydroxide water solution, mixing, centrifuging, separating precipitate to obtain Fe₃O₄@ ZnO; adding thioacetamide to react to obtain Fe₃O₄@ ZnO-ZnS support;

(2) mixing Fe₃O₄Dispersing the @ ZnO-ZnS carrier in an ethanol water solution, adding 3-aminopropyl-triethoxysilane, reacting, filtering to obtain Fe with an aminated core-shell structure₃O₄@ ZnO-ZnS substrate; amination of core-shell structures Fe₃O₄Dispersing the @ ZnO-ZnS substrate in sodium phosphate buffer solution, adding glutaraldehyde solution, stirring, centrifuging, separating precipitate, and freeze-drying to obtain aldehyde-modified aminated core-shell structure Fe₃O₄@ ZnO-ZnS support;

(3) modifying aldehyde group to aminate core-shell structure Fe₃O₄The @ ZnO-ZnS carrier is dispersed in phosphoric acid buffer solution, added with lipase, stirred, centrifuged, separated from solid, and freeze-dried to obtain the magnetic lipase-loaded photocatalyst.

Preferably, said Fe of step (1)₃O₄The mass-volume ratio of the ethanol to the ethanol water solution is 1g: 1-5 mL; the volume concentration of the ethanol aqueous solutionThe degree is 60-80%; the dosage of the zinc acetate is Fe₃O₄10-100 times of the mass; the dosage of the sodium hydroxide aqueous solution is Fe₃O₄5-50 times of the mass; the mass concentration of the sodium hydroxide aqueous solution is 20-30%; the centrifugation is carried out at 8000-20000 rpm for 15-30 min; the addition amount of the thioacetamide is Fe₃O₄@ ZnO is 1-5 times of the mass; the reaction is carried out at 60-80 ℃ for 0.5-2 h.

Preferably, said Fe of step (2)₃O₄The mass-volume ratio of the @ ZnO-ZnS carrier to the ethanol aqueous solution is 1g: 1-10 mL; the volume concentration of the ethanol water solution is 60-80%; the addition amount of the 3-aminopropyl-triethoxysilane is Fe₃O₄The mass of the @ ZnO-ZnS carrier is 1-10 times that of the carrier; the reaction is carried out for 5-6 h at 50-60 ℃; said aminated core-shell structure Fe₃O₄The mass-volume ratio of the @ ZnO-ZnS substrate to the sodium phosphate buffer solution is 1g: 10-100 mL; the pH value of the sodium phosphate buffer solution is 6.5-8; the addition amount of the glutaraldehyde solution is amination core-shell structure Fe₃O₄0.2-1 time of the mass of the @ ZnO-ZnS substrate; the mass concentration of the glutaraldehyde solution is 15-25%; the stirring is carried out at 50-500 rpm for 2-4 h, and the centrifugation is carried out at 8000-20000 rpm for 15-30 min.

Preferably, the aldehyde group modified aminated core-shell structure Fe in step (3)₃O₄The mass-volume ratio of the @ ZnO-ZnS carrier to the phosphoric acid buffer solution is 1g: 1-10 mL; the pH value of the phosphoric acid buffer solution is 6.5-8; the addition amount of the lipase is aldehyde group modified aminated core-shell structure Fe₃O₄1-10% of the mass of the @ ZnO-ZnS substrate; the stirring is carried out at the temperature of 0-4 ℃ and at the rpm of 50-500 for 4-8 h, and the centrifugation is carried out at the rpm of 8000-20000 for 15-30 min.

Preferably, said Fe₃O₄The preparation method comprises the following steps:

dissolving ferrous sulfate and ferric chloride in water at a mass ratio of 1: 1-3 to obtain a mixed solution; heating to 80-90 ℃, adding concentrated ammonia water, uniformly mixing, centrifuging at 8000-20000 rpm for 15-30 min, separating and precipitating to obtain Fe₃O₄(ii) a The concentration of the ferrous iron in the mixed solution is 0.1-0.5M; the adding amount of the strong ammonia water is 0.25-0.5 time of the mass of iron in the mixed solution.

Preferably, the Lipase in the step (3) is more than one of Lipozyme 435, Lipozyme RMIM, Lipozyme TLIM, Lipase G50 and Lipase F-AP.

The application of the magnetic lipase-loaded photocatalyst in preparation of long-chain triglyceride is disclosed.

Preferably, said application comprises the following steps;

two kinds of C are mixed₈～C₁₈Mixing fatty acids according to a molar ratio of 1-3: 1, mixing with glycerol, adding a magnetic lipase-loaded photocatalyst, and illuminating with a 5-100W incandescent lamp for 10-30 min to obtain medium-long chain triglyceride;

said C is₈～C₁₈The molar ratio of the fatty acid to the glycerol is 3-5: 1; the addition amount of the magnetic lipase-supported photocatalyst is C₈～C₁₈1-10% of the total mass of the fatty acid and the glycerol.

Preferably, said C₈～C₁₈The fatty acid is two of caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid and linoleic acid.

The principle of the invention is as follows: firstly synthesizing Fe with a magnetic core-shell structure by adopting a precipitation-deposition wrapping mode₃O₄The @ ZnO-ZnS carrier is subjected to surface modification through amino and aldehyde groups to obtain Fe with a plurality of fixing sites on the surface₃O₄The @ ZnO-ZnS carrier is favorable for modification of lipase on Fe₃O₄The @ ZnO-ZnS support is covalently bound. ZnO has photoinduced holes with strong oxidizing capability, ZnS has a large number of photo-generated electrons and a highly negative reduction potential, and ZnO and ZnS have similar band gaps and high electron mobility; under the condition of visible light, the ZnO-ZnS heterostructure in the substrate can generate electron migration as a shell, and has a synergistic effect with lipase, so that the yield of medium-long chain triglyceride is improved.

Compared with the prior art, the invention has the following advantages and effects:

(1) after the lipase is covalently immobilized, the stability of the lipase is improved, and a foundation is laid for the subsequent homogeneous reaction.

(2) The invention uses magnetic Fe₃O₄The nano particles are cores, and the lipase can be conveniently and quickly separated under the action of an external magnetic field.

(3) The invention takes a ZnO-ZnS heterostructure as a shell, combines photocatalysis and enzyme catalysis, and the synergistic effect of the two can not only not reduce the enzyme activity but also improve the catalytic activity.

Drawings

FIG. 1a shows Fe₃O₄A TEM image of the nanoparticle core;

FIG. 1b is Fe₃O₄TEM image of @ ZnO-ZnS;

FIG. 1c is Fe₃O₄TEM image of @ ZnO-ZnS-loaded lipase;

FIG. 1d is Fe₃O₄XRD patterns of different concentrations of @ ZnO-ZnS;

FIG. 2 shows the Lipozyme 435, Lipozyme/Fe free lipases in example 1₃O₄@ ZnO-ZnS (Lipase-carrying), Lipozyme/Fe₃O₄@ ZnO-ZnS (Lipase-loaded and light-irradiated) and Lipozyme/Fe₃O₄Comparative plot of medium and long chain triglyceride yields for the catalyst.

Detailed Description

The present invention will be described in further detail with reference to examples, but the embodiments of the present invention are not limited thereto.

Example 1

(1) Dissolving ferrous sulfate and ferric chloride in deionized water at a mass ratio of 1:1 (to make ferrous concentration 0.1M), heating to 80 deg.C, adding 0.25 times of concentrated ammonia water, mixing, centrifuging at 8000rpm for 30min, separating precipitate to obtain Fe₃O₄A core; dispersing the mixture into ethanol water solution (volume concentration is 60%) according to the mass volume ratio of 1:1(g/mL), and adding Fe₃O₄Mixing zinc acetate 10 times of the core mass and sodium hydroxide aqueous solution 5 times of the core mass (mass concentration 20%), centrifuging at 8000rpm for 30min, separating precipitate to obtain Fe₃O₄@ ZnO; according to their naturesAdding thioacetamide with the amount of 1 time of the total amount of the raw materials, and reacting for 2 hours at 60 ℃ to obtain Fe₃O₄@ ZnO-ZnS support.

(2)Fe₃O₄The @ ZnO-ZnS carrier was dispersed in an aqueous ethanol solution (60%) at a mass-to-volume ratio of 1:1(g/mL), and Fe was added₃O₄3-aminopropyl-triethoxysilane with the mass 1 time of the @ ZnO-ZnS carrier is reacted for 5 hours at 50 ℃ and filtered to obtain the Fe with the aminated core-shell structure₃O₄@ ZnO-ZnS substrate; the mixture was dispersed in a sodium phosphate buffer (pH 6.5) at a mass/volume ratio of 1:10(g/mL), and an aminated core-shell structure Fe was added₃O₄0.2 time of glutaraldehyde aqueous solution (mass fraction of 25%) of the mass of the @ ZnO-ZnS substrate, stirring at 50rpm for 4h at room temperature, centrifuging at 8000rpm for 30min, separating precipitate, and freeze-drying to obtain aldehyde-modified aminated core-shell structure Fe₃O₄@ ZnO-ZnS support.

(3) Aldehyde group modified aminated core-shell structure Fe₃O₄The @ ZnO-ZnS substrate is dispersed in a phosphoric acid buffer solution (pH 6.5) in a mass-to-volume ratio of 1:1(g/mL), and aldehyde modified aminated core-shell structure Fe is added₃O₄And the lipase Lipozyme 435 with the mass of 1% of the substrate of @ ZnO-ZnS is stirred at 50rpm at 0 ℃ for 8h, centrifuged at 8000rpm for 30min, separated from solid, and freeze-dried to obtain the magnetic lipase-loaded photocatalyst.

(4) Mixing caprylic acid and stearic acid at a molar ratio of 1:1, mixing with glycerol at a molar ratio of 3:1, adding 1% by mass of the mixture of magnetic lipase-loaded photocatalyst, and illuminating with 100W incandescent lamp for 10min to obtain a yield of medium-long chain triglyceride of 82%.

Example 2

(1) Dissolving ferrous sulfate and ferric chloride in deionized water at a mass ratio of 1:3 (to make ferrous concentration 0.5M), heating to 90 deg.C, adding 0.5 times of concentrated ammonia water, mixing, centrifuging at 20000rpm for 15min, separating precipitate to obtain Fe₃O₄A core; dispersing the mixture into ethanol water solution (volume concentration is 80%) according to the mass volume ratio of 1:5(g/mL), and adding Fe₃O₄Mixing zinc acetate 100 times of core mass and sodium hydroxide water solution 50 times of core mass (30% mass), centrifuging at 20000rpm for 15min, separating and precipitatingPrecipitating to obtain Fe₃O₄@ ZnO; adding thioacetamide according to the mass of 5 times of the Fe-Fe alloy, and reacting for 0.5h at the temperature of 80 DEG C₃O₄@ ZnO-ZnS support.

(2)Fe₃O₄The @ ZnO-ZnS carrier was dispersed in an aqueous ethanol solution (80%) at a mass-to-volume ratio of 1:10(g/mL), and Fe was added₃O₄3-aminopropyl-triethoxysilane with 10 times of the mass of the @ ZnO-ZnS carrier is reacted for 5 hours at the temperature of 60 ℃ and filtered to obtain the Fe with the aminated core-shell structure₃O₄@ ZnO-ZnS substrate; dispersing the mixture in a sodium phosphate buffer (pH 8) at a mass/volume ratio of 1:100(g/mL), and adding Fe with an aminated core-shell structure₃O₄Glutaraldehyde aqueous solution (mass fraction 15%) with mass 1 time of that of the @ ZnO-ZnS substrate is stirred at 500rpm at room temperature for 2h, centrifuged at 20000rpm for 15min, separated, precipitated and freeze-dried to obtain aldehyde-modified aminated core-shell structure Fe₃O₄@ ZnO-ZnS support.

(3) Aldehyde group modified aminated core-shell structure Fe₃O₄The @ ZnO-ZnS substrate is dispersed in a phosphoric acid buffer solution (pH 8) at a mass-to-volume ratio of 1:10(g/mL), and aldehyde modified aminated core-shell structure Fe is added₃O₄The preparation method comprises the following steps of @ ZnO-ZnS substrate, 5% of Lipase RMIM and 3% of Lipase G50 by mass, stirring at the temperature of 4 ℃ and 500rpm for 4h, centrifuging at the speed of 20000rpm for 15min, separating solids, and freeze-drying to obtain the magnetic Lipase-loaded photocatalyst.

(4) Mixing lauric acid and oleic acid at a molar ratio of 2:1, mixing with glycerol at a molar ratio of 5:1, adding 10% by mass of the mixture of a magnetic lipase-supported photocatalyst, and illuminating with a 5W incandescent lamp for 30min to obtain a yield of medium-long chain triglyceride of 93%.

Example 3

(1) Dissolving ferrous sulfate and ferric chloride in deionized water at a mass ratio of 1:2 (to make ferrous concentration 0.3M), heating to 85 deg.C, adding 0.4 times of concentrated ammonia water, mixing, centrifuging at 10000rpm for 20min, and separating precipitate to obtain Fe₃O₄A core; dispersing the mixture into ethanol water solution (volume concentration is 70%) according to the mass volume ratio of 1:3(g/mL), and adding Fe₃O₄50 times of zinc acetate and 10 times of oxyhydrogen based on the mass of the coreMixing sodium chloride water solution (mass concentration 25%), centrifuging at 10000rpm for 20min, separating precipitate to obtain Fe₃O₄@ ZnO; adding thioacetamide according to the mass of 3 times of the Fe-Fe alloy, and reacting for 1h at 70 DEG C₃O₄@ ZnO-ZnS support.

(2)Fe₃O₄The @ ZnO-ZnS carrier was dispersed in an aqueous ethanol solution (70%) at a mass/volume ratio of 1:5(g/mL), and Fe was added₃O₄3-aminopropyl-triethoxysilane with 5 times of the mass of the @ ZnO-ZnS carrier is reacted for 5.5h at 55 ℃ and filtered to obtain the Fe with the aminated core-shell structure₃O₄@ ZnO-ZnS substrate; dispersing the mixture in a sodium phosphate buffer (pH 7) at a mass/volume ratio of 1:50(g/mL), and adding Fe with an aminated core-shell structure₃O₄0.5 time of glutaraldehyde aqueous solution (mass fraction is 20%) of the mass of the @ ZnO-ZnS substrate, stirring at 300rpm for 3h at room temperature, centrifuging at 10000rpm for 20min, separating and precipitating, and freeze-drying to obtain aldehyde group modified aminated core-shell structure Fe₃O₄@ ZnO-ZnS support.

(3) Aldehyde group modified aminated core-shell structure Fe₃O₄The @ ZnO-ZnS substrate is dispersed in a phosphoric acid buffer solution (pH 7) at a mass-to-volume ratio of 1:5(g/mL), and aldehyde modified aminated core-shell structure Fe is added₃O₄3% of Lipase Lipozyme TLIM and 2% of Lipase F-AP based on the mass of the @ ZnO-ZnS substrate, stirring for 6h at the temperature of 2 ℃ and 300rpm, centrifuging for 20min at the speed of 10000rpm, separating solid, and freeze-drying to obtain the magnetic Lipase-loaded photocatalyst.

(4) Mixing capric acid and palmitic acid at a molar ratio of 3:1, mixing with glycerol at a molar ratio of 4:1, adding 5% by mass of the mixture of magnetic lipase-supported photocatalyst, and illuminating with 50W incandescent lamp for 20min to obtain a yield of medium-long chain triglyceride of 95%.

Test 1

Structural characterization of the product obtained in example 1

The method comprises the following steps: fe obtained in example 1₃O₄Nanoparticle core, Fe₃O₄The @ ZnO-ZnS substrate and the lipase-loaded photocatalyst thereof are subjected to X-ray diffraction (XRD) analysis and Transmission Electron Microscope (TEM) observation by taking a proper amount of the substrate.

As a result: as shown in fig. 1. FIG. 1a shows Fe₃O₄TEM image of the nanoparticle core, Fe thereof₃O₄The nano-particles are spherical; FIG. 1b is Fe₃O₄In a TEM image of @ ZnO-ZnS, a ZnO-ZnS nanoshell is obviously wrapped outside a nanoparticle core, which indicates that the substrate has a core-shell structure; FIG. 1c is Fe₃O₄The structure of the TEM image of the @ ZnO-ZnS loaded lipase is enlarged, and the shape of the TEM image is irregular, which indicates that the loading of the lipase is successful; FIG. 1d is Fe₃O₄XRD patterns of different concentrations of @ ZnO-ZnS, indicating Fe₃O₄The @ ZnO-ZnS lipase-loaded photocatalyst reserves a better core-shell structure, so that the stable photocatalytic activity of the photocatalyst is ensured.

Test 2

The product obtained in example 1 was analyzed for the content of medium-and long-chain triglycerides.

The method comprises the following steps: the product obtained in example 1 was subjected to high performance liquid chromatography using a low-temperature evaporative light scattering detector to determine the content of long-chain triglycerides.

As a result: as shown in fig. 2. In the figure, the 1 st to 6 th columns are respectively free lipase Lipozyme 435 and Lipozyme/Fe₃O₄@ ZnO-ZnS (Lipase-carrying), Lipozyme/Fe₃O₄@ ZnO-ZnS (Lipase-loaded and light-irradiated), Lipozyme/Fe₃O₄Lipozyme/ZnO-ZnS and pure carrier Fe₃O₄Comparison of yields of medium and long chain triglycerides produced by catalysis of @ ZnO-ZnS, indicating immobilization of Lipozyme 435 Lipase to Fe₃O₄After the @ ZnO-ZnS carrier is loaded, the activity of the material is superior to that of the material which is not fixed free lipase and is only Fe₃O₄Or ZnO-ZnS carrier immobilized lipase and pure carrier Fe₃O₄@ ZnO-ZnS; under the illumination condition, Lipozyme/Fe₃O₄@ ZnO-ZnS (labeled lipase/Fe in the figure)₃O₄The yield of the medium-long chain triglyceride of the @ ZnO-ZnS-1) is also improved compared with that of the non-light illumination, which indicates that the enzyme catalysis and the photocatalysis generate synergistic action.

Comparative example 1 (increasing enzyme dosage)

This comparative example differs from example 1 in that: in the step (3), the usage amount of the lipase Lipozyme 435 accounts for 20% of the substrate. The catalytic activity was determined according to test 2.

As a result, the content of medium-and long-chain triglycerides catalytically produced was 68.5%, and the yield was lowered because the lipase Lipozyme 435 was used in an excessively large amount, which resulted in incomplete immobilization and formation of excessive free lipase.

Comparative example 2 (reduction of the proportion of the shell in the core-shell Structure)

This comparative example differs from example 1 in that: the mass of the zinc acetate in the step (1) is nano Fe₃O₄The mass of the core is 5 times. The catalytic activity was determined according to test 2.

As a result, the content of long-chain triglyceride in the catalytically formed product was 58.7%, and the yield was lowered because the proportion of the shell in the core-shell structure was too low, resulting in low photocatalytic activity, and thus the lipase activity could not be effectively activated.

The above examples of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.