阅读说明：本技术 人造真菌黑色素材料的制备及紫外防护应用 (Preparation of artificial fungus black material and application of ultraviolet protection ) 是由 李乙文 黄楚皓 于 2021-07-09 设计创作，主要内容包括：一种人造真菌黑色素纳米粒子的制备方法,包括以下步骤：在空气氛围下,将黑色素前体溶于溶剂中,调节pH值为3-4,搅拌得A溶液；将铜化合物催化剂溶于水中,配制的B溶液；将A溶液于搅拌下在金属浴上加热升温,搅拌下将B溶液加入A中,混合均匀,反应得反应液；将反应液离心,沉淀清洗超声分散后再次离心,重复多次,得到人造真菌黑色素纳米粒子；将人造真菌黑色素纳米粒子在去离子水中分散保存。该方法副反应少,成本低,产率高,操作简单工艺流程短,可重复性好。可以通过调节反应条件和原料配比来调控纳米粒子的粒径,粒径在60-700nm间。所得纳米粒子有较好紫外吸收的能力,明显强于在紫外防护领域使用的聚多巴胺材料,有望作为新的紫外防护添加剂。(A preparation method of artificial fungus melanin nano-particles comprises the following steps: dissolving a melanin precursor in a solvent in the air atmosphere, adjusting the pH value to 3-4, and stirring to obtain a solution A; dissolving a copper compound catalyst in water to prepare a solution B; heating the solution A on a metal bath under stirring, heating, adding the solution B into the solution A under stirring, uniformly mixing, and reacting to obtain a reaction solution; centrifuging the reaction solution, washing the precipitate, ultrasonically dispersing, centrifuging again, and repeating for multiple times to obtain artificial fungus melanin nano particles; dispersing and storing the artificial fungus melanin nano particles in deionized water. The method has the advantages of less side reaction, low cost, high yield, simple operation, short process flow and good repeatability. The particle size of the nano particles can be regulated and controlled by adjusting reaction conditions and raw material proportion, and the particle size is between 60 and 700 nm. The obtained nano particles have better ultraviolet absorption capacity, are obviously stronger than poly-dopamine materials used in the field of ultraviolet protection, and are expected to be used as new ultraviolet protection additives.)

1. A preparation method of artificial fungus melanin nano-particles comprises the following steps:

dissolving a melanin precursor in a solvent in the air atmosphere, adjusting the pH value to 3-4, and stirring to obtain a solution A;

dissolving a copper compound catalyst in water to prepare a solution B;

heating the solution A on a metal bath under stirring, heating, adding the solution B into the solution A under stirring, uniformly mixing, and reacting to obtain a reaction solution;

centrifuging the reaction solution, washing the precipitate, ultrasonically dispersing, centrifuging again, and repeating for multiple times to obtain artificial fungus melanin nano particles;

dispersing and storing the artificial fungus melanin nano particles in deionized water.

2. The method for preparing the artificial fungus melanin nanoparticles according to claim 1, wherein the method comprises the following steps: the melanin precursor is dihydroxy naphthalene and various derivatives thereof or a mixture of any one or more of naphthol and various derivatives thereof;

the copper compound is soluble salt or copper oxide or basic salt;

the solvent is a mixed solution of acetonitrile, ethanol, methanol, acetone, tetrahydrofuran or dioxane and water.

3. The method for preparing the artificial fungus melanin nanoparticles according to claim 1, wherein the method comprises the following steps: the melanin precursor is 1, 8-dihydroxy naphthalene, the copper compound is copper sulfate, and the solvent is a mixed solution of acetonitrile and water.

4. The method for preparing the artificial fungus melanin nanoparticles according to claim 3, wherein the method comprises the following steps: the concentration of the melanin precursor in the mixed solution is 0.75-1.5 mg/mL.

5. The method for preparing artificial fungus melanin nanoparticles according to claim 2 or 3, wherein the artificial fungus melanin nanoparticles comprise: the molar ratio of the copper ions to the 1, 8-dihydroxynaphthalene in the mixed solution is 0.06-0.12.

6. The method for preparing artificial fungus melanin nanoparticles according to claim 2 or 3, wherein the artificial fungus melanin nanoparticles comprise: the mixed solution of the acetonitrile and the water is characterized in that the ratio of the acetonitrile to the deionized water is 1: 9.

7. The method for preparing artificial fungus melanin nanoparticles according to claim 2 or 3, wherein the artificial fungus melanin nanoparticles comprise: the reaction temperature is 10-70 ℃.

8. The method for preparing artificial fungus melanin nanoparticles according to claim 2 or 3, wherein the artificial fungus melanin nanoparticles comprise: the reaction time is 1-24 h.

9. The method for preparing artificial fungus melanin nanoparticles according to claim 2 or 4, wherein the artificial fungus melanin nanoparticles comprise: the solvent ratio of the solution A to the solution B is 2000: 1.

10. An artificial fungal melanin nanoparticle, characterized by: prepared by the process of any one of claims 1 to 9.

11. The application of the artificial fungus melanin nano-particles in resisting ultraviolet rays is characterized in that: the artificial fungus melanin nano particles prepared by the method are used as an antioxidant additive.

Technical Field

The invention relates to preparation and ultraviolet protection application of an artificial fungus black material, in particular to a fungus melanin nano particle, a preparation method and ultraviolet protection application thereof, and belongs to the technical field of melanin materials.

Background

Melanin is a natural pigment present in many organisms, such as animals, plants and microorganisms, known for its role in human skin pigmentation, however, it also functions in a variety of ways, such as metal ion complexation, free radical quenching, photoprotection, neuroprotection, and the like. Melanin can be divided into five types according to its structure: eumelanin, brown melanin, neuromelanin, purulent melanin, and allomelanin. The melanin is a nitrogen-free melanin, and is usually present in plants, fungi, and other organisms.

The fungal melanin synthesized from 1, 8-Dihydroxynaphthalene (DHN), otherwise known as DHN-melanin, is one of the melanoidins found in a fungus grown under high-intensity ionizing radiation, which is not viable in most organisms, at the Chinobel nuclear power plant (Microbiol.2008,11, 525-. In fungi, the fungal melanin contributes to their existence in harsh environments by acting as an essential component of the cell wall, increasing their rigidity, hydrophobicity, negative charge and reducing their porosity (Biochemistry 2005,44, 3683-. In addition, the fungal melanin can protect these fungi from high doses of radiation, and in some cases gamma radiation has proven beneficial for certain species of melanotic fungi found on space ships and in chernobyl reactors (PLoS One 2007,2, e 457). Given the myriad of functions of natural melanin and the complexity of their inherent chemical properties, synthetic artificial black materials provide a promising approach to analyze the structure and function of melanin.

In terms of synthesis, strong oxidant oxidation (ACS Nano 2019,13,10, 10980-. The fungal melanin prepared by oxidation with a strong oxidizing agent has a uniform particle size but a small adjustable range, and the oxidizing agent brings about many side reactions and byproducts, which may adversely affect the material. The ammonia gas catalyzed solid phase polymerization is limited to the preparation of the coating on the surface of the medium, and has limitation on the use environment. These limitations make it even more desirable to develop new methods for the preparation of artificial fungal melanotic materials, where biomimetic synthesis by biomimetics in a living organism is more advantageous for obtaining artificial fungal melanotic materials structurally close to the melanin of the natural fungus. Biomimetic synthesis of artificial fungal melanin is currently performed by enzymatic polymerization, most commonly horseradish peroxidase (HRP) (ChemPlusChem 2019,84(9),1331-1337) and laccase (ACS Nano 2019,13,10, 10980-10990). However, when the enzyme is used for synthesizing the fungal melanin under the artificial condition, the synthesized fungal melanin material is mostly heterogeneous in shape because of no many regulation mechanisms like in organisms. And the enzyme activity is affected by many factors, making reproducibility poor. More importantly, the production process of the enzyme is complex, the price is high, and the enzyme is not beneficial to large-scale use.

Disclosure of Invention

In order to solve the problems, the invention provides a preparation method of an artificial fungus melanin nano particle, an artificial fungus melanin nano particle and application of the artificial fungus melanin nano particle in ultraviolet protection.

In one aspect, the invention provides a preparation method of a fungus melanin nanoparticle, which comprises the following steps:

a preparation method of artificial fungus melanin nano-particles comprises the following steps:

dissolving melanin precursor in solvent in air atmosphere, adjusting pH to 3-4, and stirring to obtain solution A.

Dissolving the copper compound catalyst in water to prepare a solution B.

Heating the solution A on a metal bath under stirring, heating, adding the solution B into the solution A under stirring, uniformly mixing, and reacting to obtain a reaction solution.

And centrifuging the reaction solution, washing the precipitate, ultrasonically dispersing, centrifuging again, and repeating for multiple times to obtain the artificial fungus melanin nano particles.

Dispersing and storing the artificial fungus melanin nano particles in deionized water.

Furthermore, in the preparation method of the artificial fungus melanin nano-particles, the melanin precursor is a mixture of any one or a combination of several of dihydroxy naphthalene (naphthalenediol) and various derivatives thereof. Specifically, 1, 8-dihydroxynaphthalene, 2, 7-dihydroxynaphthalene, 2, 6-dihydroxynaphthalene, 1, 5-dihydroxynaphthalene, 1, 4-dihydroxynaphthalene, 2, 3-dihydroxynaphthalene and the like.

Further, according to the preparation method of the artificial fungus melanin nano-particle, the melanin precursor is 1, 8-dihydroxy naphthalene.

Further, in the preparation method of the artificial fungus melanin nano-particles, the solvent is a mixed solution of acetonitrile, ethanol, methanol, acetone, tetrahydrofuran or dioxane and water.

Further, in the preparation method of the artificial fungus melanin nano-particles, the solvent is a mixed solution of acetonitrile and water.

Furthermore, in the preparation method of the artificial fungus melanin nano-particles, the copper compound is soluble salt or copper oxide and basic salt. Specifically, copper sulfate, copper nitrate, copper chloride, copper acetate, copper oxide, cuprous oxide or basic copper carbonate.

Furthermore, in the preparation method of the artificial fungus melanin nano-particles, the copper compound is copper sulfate.

Further, in the preparation method of the artificial fungus melanin nano-particles, the concentration of the 1, 8-dihydroxynaphthalene in the mixed solution is 0.75-1.5 mg/mL.

Further, in the preparation method of the artificial fungus melanin nano-particles, the concentration of the 1, 8-dihydroxynaphthalene in the mixed solution is 1-1.25 mg/mL.

Furthermore, in the preparation method of the artificial fungus melanin nano-particles, the molar ratio of copper ions to 1, 8-dihydroxy naphthalene in the mixed solution is 0.06-0.12.

Furthermore, in the preparation method of the artificial fungus melanin nano-particles, the molar ratio of copper ions to 1, 8-dihydroxy naphthalene in the mixed solution is 0.06-0.08.

Further, the preparation method of the artificial fungus melanin nano-particles comprises the step of mixing acetonitrile and water, wherein the ratio of the acetonitrile to the deionized water is 1: 9.

Furthermore, the reaction temperature of the preparation method of the artificial fungus melanin nano particles is 10-70 ℃.

Furthermore, the reaction temperature of the preparation method of the artificial fungus melanin nano particles is 50 ℃.

Furthermore, the reaction time of the preparation method of the artificial fungus melanin nano particles is 1-24 h.

Furthermore, the reaction time of the preparation method of the fungus melanin nano-particles is 12-20 h.

Furthermore, in the preparation method of the fungal melanin nanoparticles, the solvent ratio of the solution A to the solution B is 2000:1, that is, the water ratio of the solvent of the solution A to the solution B is 2000: 1.

Furthermore, the particle diameter of the fungus melanin nano particle obtained by the preparation method of the fungus melanin nano particle is 70-300 nm.

On the other hand, the invention also provides an artificial fungus melanin nano particle prepared by the method.

On the other hand, the invention also provides application of the artificial fungus melanin nano particles in ultraviolet protection, and the artificial fungus melanin nano particles prepared by the method are used as ultraviolet protection additives.

By adopting the technical scheme, the invention achieves the following technical effects.

The preparation method of the artificial fungus melanin nano particles has the advantages of few side reactions, low cost, high yield, simple operation, short process flow and good repeatability.

The preparation method of the artificial fungus melanin nano-particles can regulate and control the particle size of the nano-particles by adjusting the reaction conditions and the raw material ratio, and the particle size is between 60 and 700 nm. The nano particles obtained by the invention have better ultraviolet absorption capacity, are obviously stronger than poly-dopamine materials generally used in the field of ultraviolet protection, and are expected to be used as new ultraviolet protection additives.

According to the preparation method of the artificial fungus melanin nano particles, the process of catalyzing the oxidation of the melanin precursor in the air by using the copper compound is close to the process of biosynthesis, and is milder than the process of oxidative polymerization by using an oxidizing agent.

Compared with the characteristic of high enzyme price and difficult recovery in enzyme price catalytic polymerization, the preparation method of the artificial fungus melanin nano particles has the advantages that the copper compound is relatively cheap and is more beneficial to recovery and treatment.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is an SEM photograph, a particle size statistics chart and a yield chart of artificial fungal melanin nanoparticles obtained by the methods of examples 1 to 4;

FIG. 2 is SEM pictures, particle size statistics and yield charts of the artificial fungal melanin nanoparticles of example 1, and examples 5 to 7;

FIG. 3 is SEM pictures, particle size statistics and yield charts of the artificial fungal melanin nanoparticles of example 1, and examples 8 to 10;

FIG. 4 is an SEM image of artificial fungal melanin nanoparticles of examples 11 and 12;

FIG. 5 is an SEM image of artificial fungal melanin nanoparticles and polydopamine nanoparticles of example 1 and a comparative example;

FIG. 6 is a UV-Vis spectrum of the artificial fungal melanin nanoparticles and polydopamine nanoparticles of example 1 and comparative example;

FIG. 7 is an SEM image of a PVA-nanoparticle film;

FIG. 8 is a graph showing the UV protection effect of the artificial fungal melanin nanoparticles and polydopamine nanoparticles of the comparative example of example 1.

Detailed Description

The invention provides an artificial fungus melanin material prepared by catalyzing dihydroxynaphthalene to oxidize in the air by using a copper compound, wherein the copper compound can catalyze the air to oxidize 1, 8-dihydroxynaphthalene in an aqueous solution so as to gradually polymerize the dihydroxynaphthalene to form an oligomer, the oligomer is further oxidized, and the artificial fungus melanin nano-particles are finally formed through self-assembly and covalent crosslinking.

The present invention is further illustrated by the following examples and experimental examples.

The raw materials and sources in the invention are as follows: : 98% of 1, 8-dihydroxynaphthalene and 98% of dopamine hydrochloride were purchased from Annaiji chemical (Saen chemical technology (Shanghai) Co., Ltd.).

Ammonia (25%), ethanol, acetonitrile, concentrated hydrochloric acid (37%), copper sulfate pentahydrate (analytical grade), polyvinyl alcohol 1799 were purchased from Kyoto Chemicals, Inc.

Example 1

A preparation method of artificial fungus melanin nano-particles comprises the following steps:

150mg of melanin precursor 1, 8-dihydroxynaphthalene is dissolved in a solvent of acetonitrile and water under an air atmosphere, wherein the acetonitrile is 15mL, the deionized water is 135mL, the pH value is adjusted to 3-4 by using dilute hydrochloric acid, and the solution A is stirred for about 10 minutes to obtain a solution A, wherein the concentration of the 1, 8-dihydroxynaphthalene is about 1 mg/mL.

Dissolving copper compound catalyst copper sulfate pentahydrate in water to prepare 1mol/L solution B.

Heating the solution A on a metal bath under stirring, heating to 50 ℃, adding 75 mu L of the solution B into the solution A under stirring, uniformly mixing until the molar ratio of the copper sulfate to the 1, 8-dihydroxynaphthalene is 0.08, and reacting for 20 hours to obtain a reaction solution.

And centrifuging the reaction solution on a centrifuge at the rotating speed of 12000rpm for 5 minutes, washing precipitates with deionized water, ultrasonically dispersing, centrifuging again, and repeating for three times to wash the precipitates cleanly to obtain the artificial fungus melanin nano particles.

And finally, dispersing the artificial fungus melanin nano particles in deionized water and storing the nano particles at a certain concentration, wherein the particle size of the obtained nano particles is 180 +/-24 nm and is marked as PDHN.

Examples 2 to 10

Examples 2 to 10 are essentially the same as example 1 except for the ratio of 1, 8-dihydroxynaphthalene to copper sulfate, and the temperature and reaction time, as detailed in the table below.

Examples 11 to 12

The soluble copper salt has a catalytic effect, and the acid radical ions of the soluble copper salt have little influence on the reaction, most of the soluble copper salts have similar effects, and some insoluble copper compounds can also achieve similar effects.

Examples 11 to 12 are otherwise similar to example 1 except that in examples 11 and 12, the copper compound catalyst is basic copper carbonate and copper oxide, respectively. The concentration of the 1, 8-dihydroxynaphthalene is 1.25mg/mL, the solvent is 15mL of acetonitrile and 135mL of water, the molar ratio of the copper element to the 1, 8-dihydroxynaphthalene is 0.08, and the reaction temperature is 50 ℃. An additional washing with 6M hydrochloric acid was required during the centrifugal washing after the reaction relative to example 1 to remove insoluble copper compounds that may remain.

Referring to fig. 1, which is an SEM image, a particle size statistic map and a yield map of nanoparticles obtained by the methods of examples 1 to 4, a, b, c and d correspond to SEM images of example 2, example 1, example 3 and example 4, respectively, e is a corresponding SEM particle size statistic map and f is a corresponding yield map. Wherein the molar ratio of the copper ions to the 1, 8-dihydroxynaphthalene is 0.06, 0,08, 0,10 and 0.12 respectively, and the particle size of the finally obtained particles is 110-640 nm.

Referring to fig. 2, SEM pictures, particle size statistics and yield maps of the nanoparticles of example 1, and examples 5-7, a, b, c, d correspond to SEM pictures of example 5, example 1, example 6 and example 7, respectively, e is the corresponding SEM particle size statistics, and f is the corresponding yield map. Wherein the concentration of the 1, 8-dihydroxynaphthalene is 0.75mg/mL, 1mg/mL, 1,25mg/mL and 1.5mg/mL respectively, and the particle size of the finally obtained particles is 90-637 nm.

Referring to fig. 3, SEM images, particle size statistics, and yield plots are shown for the nanoparticles of example 1, and examples 8-10, wherein a, b, c, d correspond to SEM images of example 8, example 9, example 1, and example 10, respectively, e is the corresponding SEM particle size statistics, and f is the corresponding yield plot. Wherein the reaction temperature is 10 ℃, 30 ℃, 50 ℃ and 70 ℃, and the particle diameter of the finally obtained particles is 77-145 nm.

Referring to FIG. 4, SEM images of the nanoparticles of examples 11 to 12 are shown, wherein a is the electron micrograph of the nanoparticles obtained by polymerizing 1, 8-dihydroxynaphthalene under the catalysis of basic copper carbonate in example 11, and b is the electron micrograph of the nanoparticles obtained by polymerizing 1, 8-dihydroxynaphthalene under the catalysis of copper oxide in example 12.

It can be seen from the above figures that as the molar ratio of copper ions to monomer increases, the particle size of the product increases significantly, with a slight increase in yield followed by a significant decrease in yield. The particle size of the nano particles is too small at a low concentration of copper ions, the nano particles are easy to agglomerate and cannot be separated, and the melanin precursor is more prone to be polymerized on the inner wall of the container at a high proportion of copper ions, so that the yield of the nano particles obtained by centrifugal separation is reduced. Therefore, it is preferable to control the molar ratio to be 0.06 to 0.08.

The yield and the particle size both tend to increase when the monomer concentration is increased, and the particle size is not suitable to be too large when the monomer is used as an ultraviolet protection additive, so that the monomer concentration is more suitable to be 1-1.25mg/mL comprehensively.

The nano particles have low yield and certain agglomeration phenomenon at low temperature, the agglomeration phenomenon can be obviously improved by increasing the temperature, and the yield is greatly improved under the condition of small change of the particle size. In view of energy consumption and safety, the reaction temperature is preferably around 50 ℃.

Comparative example

To demonstrate the advantage of PDHN as a material in radical scavenging, comparison was made with polydopamine nanoparticles (PDA) of similar particle size.

The preparation method of the poly-dopamine nano particles comprises the following steps: 470mg of dopamine hydrochloride is dissolved in 100mL of deionized water in an air atmosphere, 40mL of ethanol is added, and the mixture is stirred for 30 minutes and uniformly mixed.

While stirring, 2mL of ammonia water was added to adjust pH, and after 12 hours of reaction, the reaction mixture was centrifuged.

The rotation speed was 14000rpm, and the plate was washed 3 times with deionized water.

The size of the obtained polydopamine nano-particle (marked as PDA) is 174 +/-9 nm.

Experimental example:

SEM image

Referring to fig. 5, SEM images of the nanoparticles of example 1 and comparative example are shown.

Evaluation of ultraviolet protective Capacity

The ultraviolet-visible spectrum of the nanoparticle aqueous dispersion was measured in the following manner: PDHN nano particles are prepared into a solution of 50 mu g/mL in water, the solution is put into a quartz cuvette, and the absorbance of the solution at 200-900 nm is measured by a Perkinelmer Lambda 35UV/Vis spectrophotometer.

The artificial fungus melanin nanoparticles PDHN obtained in example 1 and the polydopamine nanoparticles of the comparative example are subjected to absorbance detection, and an ultraviolet-visible spectrum is shown in FIG. 6, and the ultraviolet absorption of the PDHN is obviously stronger than that of PDA.

Mixing PVA 179915% water solution with the artificial fungus melanin nano particle water dispersion obtained in the example 1 according to a proportion, and drying the mixture in a vacuum drying oven overnight to obtain the PVA-nano particle film, wherein the mass of the nano particles accounts for 1%, 2% and 5% of the mass of the final film respectively. The average thickness of the resulting film was about 100 μm, and was relatively uniform, and the SEM image of the PVA-nanoparticle film is shown in FIG. 7.

To evaluate the UV shielding performance of PVA nanoparticle films, photocatalysts (TiO) were used under mercury lamps₂) And (4) measuring the absorbance reduction of the degraded rhodamine B to evaluate the ultraviolet protection capability. Briefly, 50mL of rhodamine B solution (0.01mM) and 25mg TiO₂Mix in the dark for 30 minutes. The beaker mouth was covered with a prepared film, the distance between the lamp and the film being about 10 cm. The lamp was turned on with constant stirring, and the suspension was collected every 10 minutes and centrifuged to remove the photocatalyst over time. The absorbance of rhodamine B at 552nm was measured using a Perkinelmer Lambda 35UV/Vis spectrophotometer. The ultraviolet shielding performance calculation formula is I ═ At/A0 multiplied by 100%, wherein A0 is the initial absorbance of the rhodamine B solution which is not irradiated by ultraviolet rays, and A isAnd t is the absorbance of the remaining rhodamine B solution protected by the ultraviolet radiation film. The results are shown in fig. 8, and the membrane doped with PDHN can prevent rhodamine B from degrading under ultraviolet irradiation to a greater extent than that doped with PDA at the same doping amount, namely, has better ultraviolet protection capability.

The result shows that the copper compound can be used for successfully synthesizing the artificial fungus black material with excellent ultraviolet protection capability, the scanning electron microscope can observe that the particle size of the material is uniform under most reaction conditions and has obviously different particle sizes, and the particle size can be regulated and controlled to obtain the artificial fungus black nano particles with required sizes. Furthermore, the material has ultraviolet protection capability obviously higher than that of polydopamine, and has better application prospect than that of polydopamine in the aspects of ultraviolet protection additives or sun protection.

The embodiments are described in a parallel and progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.