CN107969553A - A kind of preparation method of selenium nano particle microlayer polymeric composite gel - Google Patents

Abstract

A kind of preparation method of selenium nano particle microlayer polymeric composite gel, belongs to selenium nano particle composite material technical field.Using pH sensitivities gel as the template in selenium nano particle building-up process, play the role of dimensionally stable in the building-up process of selenium, but also as the carrier of selenium nano particle, after being taken in by animal, contraction state is in the relatively low stomaches of pH, it is swollen and accelerates in the small enteral of pH higher, the selenium nano particle loaded on gel is gradually released into digestive juice, improves the absorption rate of selenium.

Description

A kind of preparation method of selenium nanoparticle polymer composite microgel

technical field

The invention relates to a preparation method of a selenium nanoparticle polymer composite microgel, in particular to a preparation method of a selenium nanoparticle pH-sensitive polymer composite microgel, and belongs to the technical field of selenium nanoparticle composite materials.

Background technique

Selenium is an essential trace element in humans and animals. It plays an irreplaceable role in improving immunity, scavenging free radicals, maintaining metabolic balance, and delaying aging. Selenium deficiency can lead to a series of physiological diseases. . Selenium supplements for animals and humans can be divided into inorganic selenium (mainly selenite) and organic selenium (including yeast selenium, amino acid selenium, etc.). Selenite is highly toxic and has a narrow range of safe applications. Excessive selenium is toxic to animals and humans. Organic selenium has a high biological availability and low acute toxicity. It is a good selenium supplement, but there are still limitations. It has certain chronic toxicity and high application cost in feed.

Nano-selenium is elemental selenium with a size range of nanoscale, which has high biological activity and significantly broadens the range of toxic dose and effective dose of selenium. The acute and chronic toxicity of nano-selenium is lower than that of sodium selenite and yeast selenium. It is a safe selenium product and has high potential application value in feed additives. After nano-selenium is ingested by humans and animals, its absorption method in the digestive tract is different from that of inorganic selenium and organic selenium. The absorption mechanism of nanoparticles in the gastrointestinal tract has not been fully elucidated. It is generally believed that nanoparticles can be absorbed intact. The absorption pathways may include: uptake into cells by intestinal epithelial cells, absorption through intercellular transport, and Peyer's patches. Ingestion, and its absorption site is mainly in the small intestine.

A variety of methods for preparing nano-selenium have been reported, among which liquid-phase chemical methods are most commonly used, such as surfactant method, microemulsion method, protein template method, polymer template method, and solid-phase reaction. Zhang Shengyi et al. prepared nano-selenium (CN 1264521C) by chitin template method; Xia Meisheng et al. prepared loaded nano-selenium (CN100389058C) by using porous mineral material template method; Tan Guolong et al. prepared nano Selenium (CN103420344B) Xu Xiang and others prepared agar-loaded nano-selenium (CN103445000B) by using the agar template method.

The nano-selenium carriers used in these processes are generally polymer substances such as polysaccharides and proteins, and porous mineral materials. The separation and release from the carrier is not considered, which may lead to the problem that the release rate of the loaded nano-selenium is difficult to control. If the release rate is too fast, it may cause the agglomeration of amorphous selenium nanoparticles and lose its activity, and if the release rate is too slow, it may be excreted from the body and cannot be used by animals.

The production cost and price of nano-selenium are significantly higher than inorganic selenium such as sodium selenite, which limits its application as a feed additive. Therefore, in order to improve the utilization efficiency of nano-selenium as a feed additive, suitable nano-selenium carriers should be selected so that It is fully adapted to the environment in the digestive tract of animals.

Contents of the invention

The technical problem to be solved by the present invention is to provide a preparation method of nano-selenium pH-sensitive polymer composite microgel in order to control the release of nano-selenium in the digestive tract. The pH-sensitive gel is used as the template and carrier of selenium nanoparticles, so that the nano-selenium can be released in the small intestine with high pH, which is the main absorption site, so as to improve the absorption and utilization rate of nano-selenium.

The technical solution adopted to solve the above technical problems consists of the following steps:

(1) Preparation of pH-sensitive polymer composite microgels;

(2) (2) using the pH-sensitive polymer composite microgel of step (1) as a template and a carrier for the synthesis of selenium nanoparticles,

The selenium salt is loaded and the selenium salt is reduced with a reducing agent at the same time, and the selenium nanoparticle polymer composite microgel is prepared.

Specifically include the following steps:

(1) Preparation of pH-sensitive polymer microgels. Disperse methyl methacrylate, methacrylic acid, N,N-methylenebisacrylamide and sodium hydroxide evenly in double distilled water, in which methyl methacrylate, methacrylic acid, N,N-methylene The mass ratio of bisacrylamide, sodium hydroxide and double distilled water is 1:0.5～1:0.05～0.2:0.1～0.5:5～15. Under nitrogen protection and stirring, add ammonium persulfate, ammonium persulfate and methyl The mass ratio of methyl acrylate is 1:0.1～0.:3, and it is reacted at a constant temperature at 40°C for 24 hours. The reaction product is washed with absolute ethanol, centrifuged, and freeze-dried to obtain pH-sensitive polymethacrylic acid microgel; The microgel is in a contracted state in the gastric juice environment (pH<2), and swells in the intestinal juice (pH in the range of 6.5-7.5);

(2) Preparation of selenium nanoparticles composite polymer microgel. Disperse the polymer microgel evenly in double distilled water to prepare a 0.5-1.0g/L microgel dispersion, add selenium salt to the microgel dispersion to make the concentration reach 0.4-2.0mmol/L , adding a reducing agent under stirring, the molar ratio of the reducing agent to the selenium salt is 1:0.4-0.5, after the addition is completed, the pH of the solution is adjusted to below 3, and precipitation is precipitated to obtain a composite polymer gel of selenium nanoparticles.

The reducing agent of the present invention is composed of one or more combinations of L-ascorbic acid, sodium thiosulfate and sodium bisulfite.

The selenium salt of the present invention has a component of sodium selenite.

Compared with the existing nano-selenium preparation process, this process uses a novel pH-sensitive gel as a template and a nano-selenium carrier. Compared with other types of templates, the three-dimensional network structure of the gel can control the size of the generated nanoparticles, and play a role in dimension stability during the synthesis of selenium, effectively controlling the particle size of the selenium nanoparticles and reducing the size of the selenium nanoparticles. agglomeration of particles.

In addition, as a carrier of Se nanoparticles, the gel can exhibit significant volume swelling/shrinking effects in response to changes in environmental pH. After entering the digestive tract, the gel-loaded active ingredient selenium nanoparticles are stable in the stomach where the pH is low, hindering the release of nano-selenium. It swells in the post-digestive tract such as the small intestine with a high pH, and the encapsulated nano-selenium diffuses into the digestive juice. At the same time, the small intestine is also the main absorption site of nanoparticles, and the released nano-selenium is quickly absorbed and utilized by the small intestine. This reduces the agglomeration of nano-selenium in the digestive juice and improves the absorption and utilization of selenium.

Description of drawings

Fig. 1 is the accompanying drawing of the content of selenium in the filtrate.

Detailed ways

Below in conjunction with the examples, the specific implementation of the present invention will be further described in detail. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

Example 1

Evenly disperse methyl methacrylate, methacrylic acid, methacrylic acid and sodium hydroxide in twice distilled water, wherein methyl methacrylate, methacrylic acid, N,N-methylenebisacrylamide, hydrogen The mass ratio of sodium and double-distilled water is 1:0.5:0.1:0.2:10. Under nitrogen protection and stirring, add ammonium persulfate. The mass ratio of ammonium persulfate to methyl methacrylate is 1:0.2. Under the conditions of constant temperature reaction for 24 hours, the reaction product was washed with absolute ethanol, centrifuged and freeze-dried to obtain pH-sensitive polymethacrylic acid microgel. Disperse the microgel evenly in double distilled water to prepare a 0.5g/L microgel dispersion, add sodium selenite to the microgel dispersion to 1.0mmol/L, after the addition is complete, stir vigorously Add 5% L-ascorbic acid aqueous solution under the state, the molar ratio of it and sodium selenite is 1:0.45, keep the reaction for 1h, then adjust the pH of the solution to 2.5 with 1mol/L hydrochloric acid, and precipitate the selenium nanoparticle composite polymer microgel precipitation .

Example 2

Evenly disperse methyl methacrylate, methacrylic acid, methacrylic acid and sodium hydroxide in twice distilled water, wherein methyl methacrylate, methacrylic acid, N,N-methylenebisacrylamide, hydrogen The mass ratio of sodium to double-distilled water is 1:1:0.2:0.3:15. Under nitrogen protection and stirring, ammonium persulfate is added. The mass ratio of ammonium persulfate to methyl methacrylate is 1:0.2. Under the conditions of constant temperature reaction for 24 hours, the reaction product was washed with absolute ethanol, centrifuged and freeze-dried to obtain pH-sensitive polymethacrylic acid microgel. Disperse the microgel evenly in double distilled water to prepare a 1g/L microgel dispersion, add sodium selenite to the microgel dispersion to 1.5mmol/L, after the addition is complete, in a state of vigorous stirring Add 2% sodium thiosulfate aqueous solution, its molar ratio to sodium selenite is 1:0.45, keep the reaction for 1h, then adjust the pH of the solution to 2.0 with 1mol/L hydrochloric acid, and obtain the selenium nanoparticle composite polymer microgel precipitation .

Example 3

The obtained selenium nanoparticle composite polymer microgel precipitate was centrifuged, freeze-dried, and the selenium content was determined according to the method of GB/T13883-2008, and the selenium content was 0.518% (mass percentage). Take 1.0 g of the selenium nanoparticle polymer microgel prepared in Example 1. Place them in 10ml 0.1mol/L hydrochloric acid solution (pH=2.0) and 10ml sodium dihydrogen phosphate-disodium hydrogen phosphate buffer solution (pH=7.0), let stand for 1, 2, 3, 4, 5, 6 hours respectively, Filter with 200nm filter membrane, measure the content of selenium in the filtrate, see accompanying drawing 1.

It can be seen from Figure 1 that the selenium content of the pH-sensitive polymer microgel of selenium nanoparticles changes slowly in an acidic environment of pH 2.0 (simulated gastric environment), and the release rate is only 62.9% after 6 hours. In the neutral environment (simulated small intestine environment), the swelling speed of the gel is accelerated, and 83.8% of the nano-selenium particles have been released after 1 hour, indicating that the selenium nanoparticles pH-sensitive polymer microgel has good pH response characteristics and can ensure sufficient nano-selenium particles. The particles reach the small intestine where they are absorbed, and rapidly swell in the small intestine to release selenium nanoparticles for absorption, thereby improving the utilization rate.

Claims (5)

1. a kind of preparation method of selenium nano particle microlayer polymeric composite gel, it is characterised in that comprise the following steps：

(1) pH sensitive high molecular weight composite microgels are prepared；

(2) selenium nano-particles reinforcement polymer-network method is prepared, pH sensitive high molecular weight composite microgels prepared by step (1) As the template and carrier of the synthesis of selenium nano particle, load selenium salt simultaneously reduces selenium salt with reducing agent at the same time, and selenium nanometer is prepared Particle microlayer polymeric composite gel.

A kind of 2. preparation method of selenium nano particle microlayer polymeric composite gel described in accordance with the claim 1, it is characterised in that Prepare pH sensitive high molecular weight microgels：By methyl methacrylate, methacrylic acid, N,N methylene bis acrylamide and hydrogen-oxygen Change sodium to be dispersed in double distilled water, wherein methyl methacrylate, methacrylic acid, N, N- methylene-bisacrylamides, The mass ratio 1 of sodium hydroxide and double distilled water:0.5~1:0.05~0.2:0.1~0.5:5~15, protect and stir in nitrogen Under state, ammonium persulfate is added, the mass ratio of ammonium persulfate and methyl methacrylate is 1：0.1~0.:3, in 40 DEG C of conditions Lower isothermal reaction 24h, reaction product are washed through absolute ethyl alcohol, centrifuge, are freeze-dried, and obtain pH sensitivity polymethylacrylic acid Microgel；The microgel is in contraction state in gastric juice environment, is swollen in intestinal juice.

A kind of 3. preparation method of selenium nano particle microlayer polymeric composite gel described in accordance with the claim 1, it is characterised in that Selenium nano-particles reinforcement polymer-network method is prepared, pH sensitive high molecular weight microgels are dispersed in redistilled water, are matched somebody with somebody The microgel dispersion of 0.5~1.0g/L is made, selenium salt is added into microgel dispersion, make its concentration reach 0.4~ 2.0mmol/L, adds reducing agent under stirring, and reducing agent is 1 with selenium salt molar ratio:0.4~0.5, adjusted after addition PH value of solution is saved to less than 3, precipitation is separated out, that is, obtains selenium nano-particles reinforcement high-molecular gel.

A kind of 4. preparation method of selenium nano particle microlayer polymeric composite gel described in accordance with the claim 1, it is characterised in that Reducing agent component is one or more of combinations of L-AA, sodium thiosulfate, sodium hydrogensulfite.

A kind of 5. preparation method of selenium nano particle microlayer polymeric composite gel described in accordance with the claim 1, it is characterised in that Selenium salt is sodium selenite.