阅读说明：本技术 一种双功能型淀粉基复合纳米颗粒及其制备方法与应用 (Bifunctional starch-based composite nanoparticle and preparation method and application thereof ) 是由 章宝 徐宝才 李小敏 潘怡 孟然 李小龙 李沛军 于 2019-10-25 设计创作，主要内容包括：本发明公开了一种双功能型淀粉基复合纳米颗粒及其制备方法与应用。所述制备方法包括：对淀粉进行水解处理形成线性糊精,采用醇-醇梯度沉淀法对其进行分级,获得分子量分布均一的线性糊精；采用氧化体系对线性糊精进行氧化处理,获得氧化糊精；使氧化糊精与姜黄素进行络合反应,形成氧化糊精-姜黄素络合物；使其与壳聚糖盐酸盐形成氧化糊精-姜黄素/壳聚糖盐酸盐复合纳米颗粒。使含有凝胶多糖的双功能型淀粉基复合纳米颗粒的水相溶液与初级乳液均匀混合,并对所获双重乳液进行钙离子诱导处理,获得双重乳液凝胶,其具有良好抗氧化性和长期储藏稳定性,可用于营养成分的保护、药物递送及化妆品的制备等领域。(The invention discloses a bifunctional starch-based composite nanoparticle and a preparation method and application thereof. The preparation method comprises the following steps: hydrolyzing starch to form linear dextrin, and grading the linear dextrin by adopting an alcohol-alcohol gradient precipitation method to obtain the linear dextrin with uniform molecular weight distribution; oxidizing the linear dextrin by adopting an oxidation system to obtain oxidized dextrin; carrying out complexation reaction on the oxidized dextrin and the curcumin to form an oxidized dextrin-curcumin complex; and then the chitosan hydrochloride and the oxidized dextrin-curcumin/chitosan hydrochloride composite nano-particles are formed. The aqueous phase solution of the bifunctional starch-based composite nano-particles containing curdlan is uniformly mixed with the primary emulsion, and the obtained double emulsion is subjected to calcium ion induction treatment to obtain the double emulsion gel, which has good oxidation resistance and long-term storage stability and can be used in the fields of nutrient component protection, drug delivery, cosmetic preparation and the like.)

1. A preparation method of bifunctional starch-based composite nanoparticles is characterized by comprising the following steps:

hydrolyzing starch to form a starch hydrolysate to obtain linear dextrin;

grading the linear dextrin by adopting an alcohol-alcohol gradient precipitation method to obtain the linear dextrin with uniform molecular weight distribution;

oxidizing the linear dextrin by using a TEMPO/NaClO/NaBr oxidation system to obtain oxidized dextrin;

performing a complexation reaction on a first mixed system containing oxidized dextrin and curcumin to form an oxidized dextrin-curcumin complex; and the number of the first and second groups,

and (3) forming the oxidized dextrin-curcumin/chitosan hydrochloride composite nanoparticles by electrostatic complexation of the oxidized dextrin-curcumin complex and the chitosan hydrochloride to obtain the bifunctional starch-based composite nanoparticles.

2. The production method according to claim 1, characterized by comprising: performing hydrolysis treatment on starch by adopting alpha-amylase and pullulanase, and performing alcohol-alcohol gradient precipitation grading to obtain linear dextrin with uniform molecular weight distribution; preferably, the preparation method specifically comprises the following steps: heating and gelatinizing corn starch, adding alpha-amylase in an acetate solution environment, carrying out hydrolysis treatment for 1-2 hours at 50-60 ℃, then heating to 100-110 ℃ for carrying out enzyme deactivation treatment for 10-20min, then cooling to 50-60 ℃, adding pullulanase for carrying out debranching treatment for 3-4 hours, finally carrying out enzyme deactivation treatment on the obtained starch hydrolysate, and then carrying out centrifugation, rotary steaming treatment and vacuum freeze drying to obtain linear dextrin; particularly preferably, the corn starch comprises any one or a combination of more than two of high amylose corn starch, common corn starch and waxy corn starch; particularly preferably, the addition amount of the alpha-amylase is 2U-6U enzyme units and the addition amount of the pullulanase is 20U-50U enzyme units in each gram of the corn starch; particularly preferably, the hydrolysis degree of the starch hydrolysate is 18.2-25.3%;

preferably, the preparation method comprises the following steps: slowly adding ethanol into the linear dextrin dispersion liquid under continuous stirring to ensure that the final concentration of the ethanol is 10-60%, then storing for 24-28 h at 4-6 ℃, and then performing centrifugal treatment to obtain linear dextrin with uniform molecular weight distribution; preferably, the polymerization degree of the linear dextrin is 20-68; preferably, the molecular weight of the linear dextrin is 3.35-10.9 KDa.

3. The method according to claim 1, comprising:

providing a mixed liquor comprising TEMPO, NaBr and water;

mixing the mixed solution with the linear dextrin, adjusting the pH value of the obtained second mixed system to 10-10.75, adding NaClO, keeping the pH value of the second mixed system unchanged, and precipitating the obtained oxidized dextrin when the oxidation degree of the linear dextrin is 30-90%;

preferably, the molar ratio of glucose units contained in the linear dextrin to TEMPO is 1: 0.01 to 0.02;

preferably, the molar ratio of the glucose units contained in the linear dextrin to the NaBr is 1: 0.1 to 0.3;

preferably, the oxidation position of the oxidized dextrin is C6 position of dextrin hydroxyl; preferably, the mass ratio of the linear dextrin to the NaClO is 25-70: 100, respectively; preferably, the oxidation degree of the oxidized dextrin is 30% -90%.

4. The method according to claim 1, comprising:

providing an ethanol solution comprising curcumin;

providing an aqueous dispersion containing the oxidized dextrin, heating the aqueous dispersion at 90-100 ℃ for 30-45 min, and then cooling the aqueous dispersion to 65-80 ℃;

uniformly mixing the ethanol solution containing the curcumin with the aqueous dispersion containing the oxidized dextrin to form the first mixed system, carrying out a complex reaction at 65-80 ℃ for 2-4 h, and carrying out post-treatment to obtain an oxidized dextrin-curcumin complex;

preferably, the concentration of curcumin in the ethanol solution containing curcumin is 4-6 mg/mL;

preferably, the concentration of the oxidized dextrin in the aqueous dispersion containing the oxidized dextrin is 8-12 mg/mL;

preferably, the load capacity of the curcumin in the oxidized dextrin-curcumin complex is 12-35 mug/mg, and the complexing rate is 8-25%.

5. The method according to claim 1, comprising: under the temperature of 20-25 ℃ and in a reaction system with the pH value of 4-4.5, the mass ratio of the oxidized dextrin-curcumin complex to the chitosan hydrochloride is 1: 5-5: 1, uniformly mixing for 30-45 min, and forming the oxidized dextrin-curcumin/chitosan hydrochloride composite nano-particles through electrostatic complexation.

6. Bifunctional starch-based composite nanoparticles prepared by the process of any one of claims 1-5; preferably, the bifunctional starch-based composite nanoparticle is spherical in shape and has a particle size of 285.3 nm-848.6 nm.

7. A method of preparing a double emulsion gel, comprising:

preparing bifunctional starch-based composite nanoparticles according to the method of any one of claims 1 to 5;

uniformly mixing chloride, gelatin or ethanol or glucose with water to form a first water phase solution, and uniformly mixing the first water phase solution with the oil phase component to form a primary emulsion;

uniformly mixing a second aqueous phase solution containing the bifunctional starch-based composite nanoparticles with the primary emulsion by adopting high-pressure homogenization and micro-jet technology to obtain a double emulsion containing curdlan; and the number of the first and second groups,

placing the double emulsion containing curdlan in water bath, adding Ca²⁺And cooling to obtain the double emulsion gel.

8. The production method according to claim 7, characterized by comprising: shearing the mixed solution of the primary emulsion and the second aqueous phase solution by adopting a high-pressure homogenization technology to form a coarse double emulsion, and then further homogenizing the coarse double emulsion for 3-5 times under 103.4-121 MPa by adopting a high-pressure microjet technology to obtain the double emulsion; preferably, the volume ratio of the primary emulsion to the second aqueous phase solution is 1: 9-5: 5; preferably, the concentration of the bifunctional starch-based composite nanoparticles in the second aqueous phase solution is 0.5-3 wt%; preferably, the gel polysaccharide in the double emulsion containing the gel polysaccharide is any one or the combination of more than two of gellan gum, konjac gum, sodium alginate and pectin; particularly preferably, the concentration of the gel polysaccharide in the double emulsion containing the gel polysaccharide is 2-8 wt%;

and/or, the chloride comprises any one or the combination of more than two of sodium chloride, potassium chloride and magnesium chloride;

and/or the volume ratio of the oil phase component to the first aqueous phase solution is 2: 8-5: 5;

and/or, the preparation method comprises the following steps: dissolving polyglycerol polyricinoleate or soybean lecithin in an oil phase solvent, and heating and stirring at 55-60 ℃ for 10-20min to prepare an oil phase component; preferably, the oil phase solvent comprises algal oil; preferably, the mass ratio of the polyglycerol polyricinoleate or the soybean lecithin to the oil phase solvent is 3-6: 100.

9. a double emulsion gel prepared by the method of any one of claims 7-8; preferably, the particle size of the liquid drop in the double emulsion gel is 25.96-73.33 μm; preferably, the double emulsion gel has viscoelasticity, self-supporting characteristics and a dense three-dimensional network structure.

10. Use of the double emulsion gel of claim 9 in the field of nutrient protection, drug delivery or cosmetic preparation.

Technical Field

The invention relates to a bifunctional starch-based composite nanoparticle and a preparation method thereof, and application of the bifunctional starch-based composite nanoparticle in preparation of stable W₁/O/W₂Application in double emulsion gel belongs to the technical field of starch deep processing.

Background

Modern food industry is focusing more and more on functional foods for improving human nutrition and health, and a large amount of bioactive substances are widely applied to various food systems. However, most of these materials have poor stability and the bioactive components are easily damaged, which limits their application in the food industry. Fat-soluble nutrients, including fat-soluble vitamins (V)_A、V_DAnd V_E) Polyunsaturated fatty acids (EPA, DHA and CLA), carotenoids and hydrophobic plant polyphenols (tea polyphenols, curcumin and isoflavones etc.), which are further limited in their application in food due to their poor solubility, easy oxidative degradation, low bioavailability and other characteristics. How to realize effective addition of bioactive substances in food and maintain the bioactivity of the bioactive substances is a great technical problem facing the food industry at present.

The construction of food-grade colloidal particles and stable Pickering emulsion (emulsion obtained by using ultrafine solid particles as an emulsifier) delivery system thereof is an important way for improving the stability and biological value of fat-soluble functional factors. However, unsaturated fatty acids and lipid-based bioactive substances in the emulsion are susceptible to oxidation during storage. This not only results in the loss of essential fatty acids and bioactive substances, but also produces more harmful substances such as peroxides, aldehydes, ketones, alcohols, hydrocarbons and acids, which not only change the organoleptic qualities such as flavor and color of the food, but also have genetic and cytotoxic properties. Ingestion of foods containing lipid oxidation products can cause damage to human tissues and organs, and seriously harm health. Numerous studies have shown that: the interface is the primary site for oxidation of the emulsion and the pro-oxidant in the continuous phase can interact with the hydroperoxide of the emulsion droplets. Therefore, designing and constructing an interface structure with oxidation defense properties is an effective way to improve the oxidative stability of emulsions.

Double emulsions are a multiple emulsion consisting of emulsion droplets of smaller droplets. The double emulsion has unique advantages in the development of micro-encapsulated, slow-release and low-fat foods due to the division of the inner region, compared to the conventional emulsion. W₁/O/W₂One major drawback of double emulsions is their poor stability, which limits their industrial applicability. The double emulsion is prepared by replacing at least one type of surfactant molecules with solid particles, a new strategy is provided for improving the stability of the double emulsion, and the application of the double emulsion in the industry is favorably expanded.

Emulsion gels are a new type of structured emulsion, fixing dispersed droplets in a tight gel network. The oil-water interface effect and the gel network structure provide better protection effect for the active ingredients. By changing the gel structure, the release and absorption of the active ingredient can be modulated.

The nano-particles with oxidation resistance and interface stability are constructed on the basis, and the nano-particles are applied to the preparation of the double emulsion gel, so that the nano-particles have important significance in improving the oxidation resistance of the lipid and the stability of the double emulsion.

Disclosure of Invention

The invention mainly aims to provide a bifunctional starch-based composite nanoparticle and a preparation method thereof, so as to overcome the defects of the prior art.

Another main object of the present invention is to provide W prepared based on the aforementioned bifunctional type starch-based composite nanoparticle₁/O/W₂Double emulsion gel and its preparation method are provided.

It is another main object of the present invention to provide the above W₁/O/W₂Use of double emulsion gels.

In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:

the embodiment of the invention provides a preparation method of bifunctional starch-based composite nanoparticles, which comprises the following steps:

hydrolyzing starch to form a starch hydrolysate to obtain linear dextrin;

grading the linear dextrin by adopting an alcohol-alcohol gradient precipitation method to obtain the linear dextrin with uniform molecular weight distribution;

oxidizing the linear dextrin by using a TEMPO/NaClO/NaBr oxidation system to obtain oxidized dextrin;

performing a complexation reaction on a first mixed system containing oxidized dextrin and curcumin to form an oxidized dextrin-curcumin complex; and the number of the first and second groups,

and (3) forming the oxidized dextrin-curcumin/chitosan hydrochloride composite nanoparticles by electrostatic complexation of the oxidized dextrin-curcumin complex and the chitosan hydrochloride to obtain the bifunctional starch-based composite nanoparticles.

In some embodiments, the preparation method specifically comprises:

providing a mixture comprising 2, 2, 6, 6-tetramethyl-1-piperidinyloxy (i.e., TEMPO), NaBr, and water;

and mixing the mixed solution with the linear dextrin, adjusting the pH value of the obtained second mixed system to 10-10.75, adding NaClO, keeping the pH value of the second mixed system unchanged, and precipitating the obtained oxidized dextrin when the oxidation degree of the linear dextrin is 30-90%.

In some embodiments, the preparation method specifically comprises:

providing an ethanol solution comprising curcumin;

providing an aqueous dispersion containing the oxidized dextrin, heating the aqueous dispersion at 90-100 ℃ for 30-45 min, and then cooling the aqueous dispersion to 65-80 ℃;

and uniformly mixing the ethanol solution containing the curcumin with the aqueous dispersion containing the oxidized dextrin to form the first mixed system, carrying out a complex reaction at 65-80 ℃ for 2-4 h, and carrying out post-treatment to obtain the oxidized dextrin-curcumin complex.

In some embodiments, the preparation method specifically comprises: under the temperature of 20-25 ℃ and in a reaction system with the pH value of 4-4.5, the mass ratio of the oxidized dextrin-curcumin complex to the chitosan hydrochloride is 1: 5-5: 1, uniformly mixing for 30-45 min, and forming the oxidized dextrin-curcumin/chitosan hydrochloride composite nano-particles through electrostatic complexation.

The embodiment of the invention also provides the bifunctional starch-based composite nano-particle prepared by the method.

The embodiment of the invention also provides a preparation method of the double emulsion gel, which comprises the following steps:

preparing bifunctional starch-based composite nanoparticles according to the method;

uniformly mixing chloride, gelatin or ethanol or glucose with water to form a first water phase solution, and uniformly mixing the first water phase solution with the oil phase component to form a primary emulsion;

uniformly mixing a second aqueous phase solution containing the bifunctional starch-based composite nanoparticles with the primary emulsion by adopting high-pressure homogenization and micro-jet technology to obtain a double emulsion containing curdlan; and the number of the first and second groups,

placing the double emulsion containing curdlan in water bath, adding Ca²⁺Inducing gel polysaccharide to generate cross-linking reaction, and cooling to obtain the double-emulsion gel.

Further, the preparation method comprises the following steps: and shearing the mixed solution of the primary emulsion and the second aqueous phase solution by adopting a high-pressure homogenization technology to form a coarse double emulsion, and then further homogenizing the coarse double emulsion for 3-5 times under 103.4-121 MPa by adopting a high-pressure microjet technology to obtain the double emulsion.

The embodiment of the invention also provides the double-emulsion gel prepared by the method.

The embodiment of the invention also provides application of the double emulsion gel in the fields of nutrient substance protection, drug delivery, cosmetic preparation and the like.

Compared with the prior art, the invention has the advantages that:

1) the invention takes renewable starch as raw material, carries out deep processing treatment on the starch, can enlarge the application range of the starch and enrich the academic content of the starch subject;

2) the linear dextrin with uniform polymerization degree is obtained by alcohol-alcohol gradient precipitation grading, the method is simple and easy to obtain, TEMPO fixed-point quantitative oxidation is adopted, the spiral cavity of the dextrin is reserved, and the complexation embedding effect of the dextrin on curcumin is facilitated;

3) the composite nano-particles are prepared by adopting an electrostatic interaction method, the reaction condition is mild, the method is simple, and the obtained nano-particles have proper wettability and are spherical and have good emulsibility and interface stability;

4) the preparation method adopts the composite nano particles to prepare the double emulsion gel, and the emulsion is stabilized through the interface layer formed by the particles and the gel network, so that the emulsion has higher stability, good oxidation resistance and long-term storage stability (180 days) compared with the emulsion stabilized by the surfactant;

5) the invention has mild reaction conditions and simple preparation method, is easy to realize large-scale production, and can be used in the fields of nutrient protection, drug delivery, cosmetic preparation and the like.

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 some embodiments described in the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIGS. 1 a-1 c are HPSEC-MALLS-RI spectra of fractionated dextrin fractions in an exemplary embodiment of the invention, respectively.

FIG. 2 is a graph illustrating particle sizes and potential levels of composite nanoparticles in various proportions according to an exemplary embodiment of the present invention.

Fig. 3 a-3 c are schematic diagrams of contact angle sizes of composite nanoparticles with different proportions according to an exemplary embodiment of the present invention.

FIG. 4a and FIG. 4b are each a W in an exemplary embodiment of the invention₁/O/W₂Lipid oxidation results for the double emulsion are shown schematically.

FIG. 5 shows W in an exemplary embodiment of the invention₁/O/W₂Storage stability results of the double emulsion are shown schematically.

Detailed Description

In view of the technical problems in the prior art, the inventors of the present invention have made extensive studies and extensive practices to provide a technical solution of the present invention, which mainly provides a method for preparing bifunctional starch-based composite nanoparticles and a method for stabilizing W using the same₁/O/W₂The application of the double emulsion gel in preparation can improve the oxidation resistance of the unsaturated algae oil and the stability of the double emulsion.

The linear dextrin prepared by the starch through the alpha-amylase and pullulanase limited hydrolysis, alcohol-alcohol gradient precipitation grading, 2, 2, 6, 6-tetramethyl-1-piperidinyloxy radical (hereinafter, referred to as TEMPO) mediated fixed-point quantitative oxidation technology has uniform polymerization degree and oxidation degree, the oxidized dextrin and the curcumin have high complexation effect, and the composite nano-particles with oxidation resistance and interface stability are constructed based on the electrostatic interaction between the oxidized dextrin and chitosan hydrochloride, and the double-emulsion gel is stabilized through the nano-particles. The method is simple and novel, the prepared double-emulsion gel has excellent oxidation resistance and stability, the preparation process related by the invention is simple, convenient, safe and pollution-free, and the industrial production is easy to realize.

In summary, the design principle of the present invention is mainly as follows: firstly, starch is subjected to limited hydrolysis by alpha-amylase and pullulanase, linear dextrin with uniform molecular weight distribution is prepared by adopting an alcohol-alcohol gradient precipitation method, and C is subjected to oxidation by a TEMPO/NaClO/NaBr-based oxidation system₆The site-directed quantitative oxidation technology is adopted to obtain oxidized dextrin with high anion property, and further the complexation embedding effect of the spiral cavity of dextrin on curcumin is utilized to prepare an oxidized dextrin-curcumin complex; based on the electrostatic interaction between the oxidized dextrin and the chitosan hydrochloride, the oxidized dextrin-curcumin/chitosan hydrochloride composite nano-particles are constructed. Taking composite nano-particle dispersion liquid containing curdlan as water phase (W)₂) Stabilization of the Water-in-oil Primary emulsion (W)₁O, wherein W₁Is mixed aqueous solution containing ethanol and NaCl, and O is algae oil containing polyglycerol polyricinoleate (PGPR) or soybean lecithin), and W with oxidation resistance and interface stability is prepared₁/O/W₂The double emulsion is formed, and the double emulsion gel with the interface stability and the gel network structure protection effect is further obtained by a calcium ion induction method.

The technical solution, its implementation and principles, etc. will be further explained as follows.

An aspect of an embodiment of the present invention provides a method for preparing bifunctional starch-based composite nanoparticles, comprising:

hydrolyzing starch to form a starch hydrolysate to obtain linear dextrin;

grading the linear dextrin by adopting an alcohol-alcohol gradient precipitation method to obtain the linear dextrin with uniform molecular weight distribution;

oxidizing the linear dextrin by using a TEMPO/NaClO/NaBr oxidation system to obtain oxidized dextrin;

performing a complexation reaction on a first mixed system containing oxidized dextrin and curcumin to form an oxidized dextrin-curcumin complex; and the number of the first and second groups,

and (3) forming the oxidized dextrin-curcumin/chitosan hydrochloride composite nanoparticles by electrostatic complexation of the oxidized dextrin-curcumin complex and the chitosan hydrochloride to obtain the bifunctional starch-based composite nanoparticles.

In some embodiments, the method of making comprises: and (3) performing hydrolysis treatment on the starch by adopting alpha-amylase and pullulanase, and performing alcohol-alcohol gradient precipitation grading to obtain the linear dextrin with uniform molecular weight distribution. The invention takes renewable starch as raw material, carries out deep processing treatment on the starch, can enlarge the application range of the starch and enrich the academic content of the starch subject.

Further, the preparation method specifically comprises the following steps: heating and gelatinizing corn starch (high-amylose corn starch, common corn starch and waxy corn starch), adding alpha-amylase in an acetate solution environment, carrying out hydrolysis treatment at 50-60 ℃ for 1-2 hours, heating to 100-110 ℃ for enzyme deactivation treatment for 10-20 minutes, cooling to 50-60 ℃, adding pullulanase for debranching treatment for 3-4 hours, finally carrying out enzyme deactivation treatment on the obtained starch hydrolysate (the hydrolysis degree is 18.2-25.3%), centrifuging, carrying out rotary steaming treatment, and carrying out vacuum freeze drying to obtain the linear dextrin.

Further, the addition amount of the alpha-amylase in each gram of the corn starch is 2U-6U of enzyme units, and the addition amount of the pullulanase is 20U-50U of enzyme units.

In some more preferred embodiments, the method for preparing the Linear Dextrin (LD) specifically comprises:

placing corn starch milk with the mass fraction of 5 wt% in a boiling water bath, stirring for 1h to completely gelatinize the starch, further placing the gelatinized starch in an acetate solution (0.02mol/L, pH value of 6), adding alpha-amylase, carrying out hydrolysis treatment for 1-2h at 50-60 ℃, heating to 100 ℃ for carrying out enzyme deactivation treatment, cooling to 50-60 ℃, adding pullulanase for carrying out debranching treatment for 3-4h, and after the reaction is finished, placing the reaction solution in the boiling water bath for carrying out enzyme deactivation treatment for 10-20 min. And centrifuging the reactant at 4500g for 20min, removing precipitates, performing rotary evaporation treatment on the supernatant, and performing vacuum freeze drying to obtain the linear dextrin.

In some embodiments, the method of making comprises: slowly adding ethanol into the linear dextrin dispersion liquid under continuous stirring to ensure that the final concentration of the ethanol is 10-60%, then storing for 24-28 h at 4-6 ℃, and then centrifuging to obtain the linear dextrin with uniform molecular weight distribution. The invention adopts alcohol-alcohol gradient precipitation grading to obtain linear dextrin with uniform polymerization degree, the method is simple and easy to obtain, TEMPO fixed-point quantitative oxidation is adopted, the spiral cavity of the dextrin is reserved, and the complexation embedding effect of the dextrin on curcumin is facilitated.

Further, the linear dextrin has a Degree of Polymerization (DP) of 20 to 68.

Further, the molecular weight range of the linear dextrin is 3.35-10.9 KDa.

In some more preferred embodiments, the method for fractionating Linear Dextrin (LD) specifically includes:

linear Dextrins (LD) were fractionated using an alcohol-alcohol gradient precipitation method. Briefly, anhydrous ethanol was slowly added to the LD dispersion under continuous stirring to give final ethanol concentrations of 10%, 20%, 30%, 40%, 50%, 60%, and the resulting precipitate fractions were centrifuged at 4500g and stored at 4 ℃ for 24h to obtain the precipitate fractions designated LD-10, LD-20, LD-30, LD-40, LD-50, LD-60.

In some embodiments, the preparation method specifically comprises:

providing a mixture comprising 2, 2, 6, 6-tetramethyl-1-piperidinyloxy radical (TEMPO), sodium bromide (NaBr), and water;

and mixing the mixed solution with the linear dextrin, adjusting the pH value of the obtained second mixed system to 10-10.75, adding NaClO, keeping the pH value of the second mixed system unchanged, and precipitating the obtained oxidized dextrin when the oxidation degree of the linear dextrin is 30-90%.

Further, the molar ratio of glucose units contained in the linear dextrin to TEMPO is 1: 0.01 to 0.02mol of TEMPO, namely, the adding amount of TEMPO is 0.01 to 0.02mol of TEMPO added per mol of linear dextrin glucose unit.

Further, the molar ratio of the glucose units contained in the linear dextrin to NaBr is 1: 0.1 to 0.3, that is, the amount of NaBr added is 0.1 to 0.3mol of NaBr per mol of linear dextrin glucose unit.

Further, the oxidation of the oxidized dextrin occurs only at C of the dextrin hydroxyl group₆On the bit.

Further, the mass ratio of the linear dextrin to the NaClO is 25-70: 100.

further, the oxidation degree of the oxidized dextrin is 30% -90%.

In some more preferred embodiments, the method for preparing oxidized dextrin specifically comprises:

a5 wt% dextrin solution was placed in an ice water bath at 5 ℃ and 2, 2, 6, 6-tetramethyl-1-piperidinyloxy free radical (TEMPO) and sodium bromide were dissolved in 100mL of distilled water. After the TEMPO was completely dissolved, the solution was added to a 5 ℃ dextrin solution and the pH of the solution was adjusted to 10.75 with 0.5mol/L NaOH. Adding a certain amount of NaClO into the dextrin solution, and simultaneously maintaining the pH of the solution unchanged by adopting a pH-stat method. When the appropriate degree of oxidation was reached, 75% ethanol was added to precipitate the desired product, and the sample was washed repeatedly with a water/acetone mixture until no Cl could be detected in the supernatant^-The precipitate obtained was washed with acetone and dried in an oven at 45 ℃.

In some embodiments, the preparation method specifically comprises:

providing an ethanol solution comprising curcumin;

providing an aqueous dispersion containing the oxidized dextrin, heating the aqueous dispersion at 90-100 ℃ for 30-45 min, and then cooling the aqueous dispersion to 65-80 ℃;

and uniformly mixing the ethanol solution containing the curcumin with the aqueous dispersion containing the oxidized dextrin to form the first mixed system, carrying out a complex reaction at 65-80 ℃ for 2-4 h, and carrying out post-treatment to obtain the oxidized dextrin-curcumin complex.

Further, the concentration of the curcumin in the ethanol solution containing the curcumin is 4-6 mg/mL.

Further, the concentration of the oxidized dextrin in the aqueous dispersion containing the oxidized dextrin is 8-12 mg/mL.

Furthermore, the load capacity of the curcumin in the oxidized dextrin-curcumin complex is 12-35 mu g/mg, and the complexing rate is 8-25%.

In some more preferred embodiments, the method for preparing the oxidized dextrin-curcumin complex specifically comprises:

the oxidized dextrin-curcumin complex is prepared by adopting a coprecipitation method. Dissolving curcumin in anhydrous ethanol (4mg/mL) as a raw solution; oxidized dextrin was dispersed in distilled water to a final concentration of 10 mg/mL. The resulting dispersion was heated at 100 ℃ for 30min and then cooled to 80 ℃. Adding curcumin with different volumes into the oxidized dextrin solution, and stirring gently at 80 ℃ for 2 h. The mixture was stored at 4 ℃ for 12h, centrifuged at 10000g for 15min to obtain a precipitate, washed 3 times with 50% absolute ethanol and dried in an oven at 40 ℃.

Further, the volumes of curcumin added to the oxidized dextrin solution were 1.5mL, 2.0mL, 3.0mL, 6mL, 9mL, and 12mL, respectively.

In some embodiments, the preparation method specifically comprises: under the temperature of 20-25 ℃ and in a reaction system with the pH value of 4-4.5, the mass ratio of the oxidized dextrin-curcumin complex to the chitosan hydrochloride is 1: 5-5: 1, uniformly mixing for 30-45 min, and forming the oxidized dextrin-curcumin/chitosan hydrochloride composite nano-particles through electrostatic complexation. The composite nano-particles are prepared by adopting an electrostatic interaction method, the reaction condition is mild, the method is simple, and the obtained nano-particles have proper wettability, are spherical and have good emulsibility and interface stability.

In some more preferred embodiments, the method for preparing the oxidized dextrin-curcumin/chitosan hydrochloride composite nanoparticle specifically comprises the following steps:

dissolving the oxidized dextrin-curcumin complex in distilled water, and stirring at 800rpm until the oxidized dextrin-curcumin complex is completely dissolved to obtain 0.5 wt% oxidized dextrin-curcumin solution; dissolving chitosan hydrochloride in distilled water to obtain 1.5 wt% chitosan hydrochloride solution; and adjusting the pH value of the two solutions by adopting 0.5mol/L HCl, further dropwise adding the oxidized dextrin-curcumin solution into the chitosan hydrochloride solution, and mixing and stirring the two solutions for 30min to promote the formation of the composite nano particles. And the obtained oxidized dextrin-curcumin/chitosan hydrochloride composite nano-particles are frozen and dried for further analysis.

Further, the pH value of the mixed solution of the oxidized dextrin-curcumin solution and the chitosan hydrochloride solution is 4-4.5.

Further, the mass ratio of the oxidized dextrin-curcumin complex to the chitosan hydrochloride may be 5: 1. 3: 1. 2: 1. 1: 1. 1: 2. 1: 3. 1:5, and the like.

Another aspect of the embodiments of the present invention also provides bifunctional type starch-based composite nanoparticles prepared by the foregoing method.

Furthermore, the grain diameter of the bifunctional starch-based composite nano-particle is 285.3-848.6 nm, the bifunctional starch-based composite nano-particle is spherical and is uniformly distributed in a spherical shape, and the bifunctional starch-based composite nano-particle has good oxidation resistance and emulsifying property.

It is yet another aspect of an embodiment of the present invention to provide a double emulsion gel (i.e., oxidized dextrin-curcumin/chitosan hydrochloride composite nanoparticle stabilized W)₁/O/W₂Type double emulsion gel) comprising:

preparing bifunctional starch-based composite nanoparticles according to the method;

uniformly mixing chlorides such as sodium chloride, potassium chloride or magnesium chloride, gelatin, ethanol or glucose with water to form a first water phase solution, and uniformly mixing the first water phase solution with the oil phase component to form a primary emulsion;

uniformly mixing a second aqueous phase solution containing the bifunctional starch-based composite nanoparticles with the primary emulsion by adopting high-pressure homogenization and micro-jet technology to obtain a double emulsion containing curdlan; and the number of the first and second groups,

treating the double emulsion containing curdlan in 80 deg.C water bath for 1 hr, adding 0.5mmol/L Ca²⁺Inducing the curdlan to generate a cross-linking reaction, and cooling to 30 to ℃The double emulsion gel with good stability is obtained at 35 ℃.

In some embodiments, the preparation method specifically comprises:

shearing the mixed solution of the primary emulsion and the second aqueous phase solution by adopting a high-pressure homogenization technology to form a coarse double emulsion, and then further homogenizing the coarse double emulsion for 3-5 times under 103.4-121 MPa by adopting a high-pressure microjet technology to obtain the W₁/O/W₂Forming double emulsion, treating the double emulsion containing curdlan in 80 deg.C water bath for 1 hr, adding 0.5mmol/L Ca²⁺Inducing gel polysaccharide to generate cross-linking reaction, and cooling to 30-35 ℃ to obtain the double-emulsion gel with good stability.

In some more preferred embodiments, said W₁/O/W₂The preparation method of the double emulsion gel specifically comprises the following steps:

a)W₁preparation of an/O emulsion

Adding PGPR into algae oil, heating and stirring at 60 deg.C for 20min to completely dissolve to prepare oil phase (O), dissolving 0.1M NaCl and 20% ethanol in distilled water to prepare water phase (W)₁) By mixing W₁Dropwise adding into oil phase, stirring at 800rpm for 30min to obtain W₁a/O macroemulsion; shearing the obtained crude emulsion at 20000rpm for 10min to obtain W₁Fine emulsion of the/O type.

b)W₁/O/W₂Preparation of double emulsion gel

W₁/O/W₂The double emulsion gel is prepared by mixing the primary emulsion W_1/O is dispersed in the water phase W in different volume ratios₂。W₂Is dispersion liquid containing curdlan with different concentrations and oxidized dextrin-curcumin/chitosan hydrochloride composite nano particles. Mixing the two, and carrying out high-pressure micro-jet treatment to obtain W₁/O/W₂The double emulsion is prepared by treating double emulsion containing curdlan in 80 deg.C water bath for 1 hr, adding 0.5mmol/L Ca²⁺And obtaining the double-emulsion gel with good stability when the temperature is cooled to 30-35 ℃.

Further, W₁/O/W₂In the preparation of the double emulsion, W₁The primary emulsion of the type/O and the second aqueous phase solution (i.e. aqueous phase W)₂) The volume ratio between 1: 9-5: 5.

further, the second aqueous phase solution (i.e., aqueous phase W)₂) The concentration of the medium-double-function starch-based composite nano-particles is 0.5 to 3 weight percent.

Further, the gel polysaccharide in the double emulsion containing gel polysaccharide is any one or a combination of more than two of gellan gum, konjac gum, sodium alginate, pectin and the like, but is not limited thereto.

Further, the concentration of the curdlan in the double emulsion containing the curdlan is 2-8 wt%.

Further, W₁In the preparation of the/O emulsion, the oil phase component is mixed with a first aqueous phase solution (i.e., aqueous phase W)₁) Is 2: 8-5: 5.

further, W₁The preparation method of the/O emulsion comprises the following steps: dissolving polyglycerol polyricinoleate or soybean lecithin in an oil phase solvent, and heating and stirring at 55-60 ℃ for 10-20min to obtain the oil phase component.

Further, the oil phase solvent includes algal oil, but is not limited thereto.

Further, the mass ratio of the polyglycerol polyricinoleate (PGPR) or the soybean lecithin to the oil phase solvent is 3-6: 100, namely the addition amount of PGPR is 3 to 6 weight percent of the algae oil.

Wherein, as one of the more preferable embodiments of the present invention, said W₁/O/W₂The preparation method of the double emulsion gel can more specifically comprise the following steps:

1) preparation of Linear Dextrin (LD)

Placing corn starch milk with the mass fraction of 5 wt% in a boiling water bath, stirring for 1h to completely gelatinize the starch, further placing the gelatinized starch in an acetate solution (0.02mol/L, pH value of 6), adding alpha-amylase, carrying out hydrolysis treatment for 1-2h at 50-60 ℃, heating to 100 ℃ for carrying out enzyme deactivation treatment, cooling to 50-60 ℃, adding pullulanase for carrying out debranching treatment for 3-4h, and after the reaction is finished, placing the reaction solution in the boiling water bath for carrying out enzyme deactivation treatment for 10 min. And centrifuging the reactant at 4500g for 20min, removing precipitates, performing rotary evaporation treatment on the supernatant, and performing vacuum freeze drying to obtain the linear dextrin.

2) Fractionation of Linear dextrins

Grading LD by adopting an alcohol-alcohol precipitation gradient precipitation method. Briefly, anhydrous ethanol was slowly added to the LD dispersion under continuous stirring to give final ethanol concentrations of 10%, 20%, 30%, 40%, 50%, 60%, and the resulting precipitate fractions were centrifuged at 4500g and stored at 4 ℃ for 24h to obtain the precipitate fractions designated LD-10, LD-20, LD-30, LD-40, LD-50, LD-60.

3) Preparation of oxidized dextrins

A5 wt% dextrin solution was placed in an ice water bath at 5 ℃ and 2, 2, 6, 6-tetramethyl-1-piperidinyloxy free radical (TEMPO) and sodium bromide were dissolved in 100mL of distilled water. After the TEMPO was completely dissolved, the solution was added to a 5 ℃ dextrin solution and the pH of the solution was adjusted to 10.75 with 0.5mol/L NaOH. Adding a certain amount of NaClO into the dextrin solution, and simultaneously maintaining the pH value of the solution unchanged by adopting a pH-stat method. When the appropriate degree of oxidation was reached, 75% ethanol was added to precipitate the desired product, and the sample was washed repeatedly with a water/acetone mixture until no Cl could be detected in the supernatant^-The precipitate obtained was washed with acetone and dried in an oven at 45 ℃.

4) Preparation of oxidized dextrin-curcumin complex

The oxidized dextrin-curcumin complex is prepared by adopting a coprecipitation method. Dissolving curcumin in anhydrous ethanol (4mg/mL) as a raw solution; oxidized dextrin was dispersed in distilled water to a final concentration of 10 mg/mL. The resulting dispersion was heated at 100 ℃ for 30min and then cooled to 80 ℃. Adding curcumin with different volumes into the oxidized dextrin solution, and stirring gently at 80 ℃ for 2 h. The mixture was kept at 4 ℃ for 12h, centrifuged at 10000g for 15min to obtain a precipitate, washed 3 times with 50% absolute ethanol and dried in an oven at 40 ℃.

5) Preparation of oxidized dextrin-curcumin/chitosan hydrochloride composite nanoparticles

Dissolving the oxidized dextrin-curcumin complex in distilled water, and stirring at 800rpm until the oxidized dextrin-curcumin complex is completely dissolved to obtain 0.5 wt% oxidized dextrin-curcumin solution; dissolving chitosan hydrochloride in distilled water to obtain 1.5 wt% chitosan hydrochloride solution; and adjusting the pH value of the two solutions by adopting 0.5mol/L HCl, further dropwise adding the oxidized dextrin-curcumin solution into the chitosan hydrochloride solution, and mixing and stirring the two solutions for 30min to promote the formation of the composite nano particles. And the obtained oxidized dextrin-curcumin/chitosan hydrochloride composite nano-particles are frozen and dried for further analysis.

The application of the oxidized dextrin-curcumin/chitosan hydrochloride composite nano-particles prepared by the invention is to replace W of double-emulsion gel₂The surfactant of the phase improves the stability of the double emulsion gel, and specifically comprises the following steps:

a)W₁preparation of an/O emulsion

Adding PGPR into algae oil, heating and stirring at 60 deg.C for 20min to completely dissolve to obtain oil phase (O), dissolving 0.1mol/L NaCl and 20% ethanol in distilled water to obtain water phase (W)₁) By mixing W₁Dropwise adding into oil phase, stirring at 800rpm for 30min to obtain W₁a/O macroemulsion; shearing the obtained crude emulsion at 20000rpm for 10min to obtain W₁Fine emulsion of the/O type.

b)W₁/O/W₂Preparation of double emulsion gel

W₁/O/W₂The double emulsion gel is prepared by mixing the primary emulsion W_1/O is dispersed in the water phase W in different volume ratios₂。W₂Is dispersion liquid containing curdlan with different concentrations and oxidized dextrin-curcumin/chitosan hydrochloride composite nano particles. Mixing the two, and carrying out high-pressure micro-jet treatment to obtain W₁/O/W₂The double emulsion is prepared by treating double emulsion containing curdlan in 80 deg.C water bath for 1 hr, adding 0.5mmol/L Ca²⁺And obtaining the double-emulsion gel with good stability when the temperature is cooled to 30-35 ℃.

Another aspect of an embodiment of the present invention also provides a double emulsion gel prepared by the foregoing method.

Furthermore, the particle size of the liquid drops in the double emulsion is 25.96-73.33 μm, and the double emulsion has good storage stability and excellent antioxidant activity.

Further, the double emulsion gel has good viscoelasticity, self-supporting characteristics and a compact three-dimensional network structure.

The invention adopts the composite nano particles to prepare the double emulsion gel, and the emulsion is stabilized by the interface layer formed by the particles and the gel network, and has higher stability, good oxidation resistance and long-term storage stability (180 days) compared with the emulsion stabilized by the surfactant.

Another aspect of the embodiments of the present invention also provides the use of the aforementioned double emulsion gel in the fields of nutrient protection, drug delivery, or cosmetic preparation.

The molecular weight of the graded dextrin is measured by adopting HPSEC-MALLS-RI; a zeta potential analyzer is adopted to measure the particle size and the potential of the composite nano particles, and the wettability of the composite nano particles is evaluated; the contents of hydroperoxide and malondialdehyde are measured by adopting an iron thiocyanate method and a thiobarbituric acid method, and the oxidation resistance of the double emulsion is evaluated; the stability of the double emulsion was evaluated by measuring the change in the particle size of the emulsion during storage using a laser particle size analyzer. The double emulsion gel stabilized by the composite nano particles has good oxidation resistance and interface stability.

In conclusion, the composite nanoparticles are prepared by adopting an electrostatic interaction method, the reaction conditions are mild, the method is simple, the obtained nanoparticles have proper wettability and spherical shape, and have good emulsibility and interface stability.

The technical solution of the present invention is further described in detail below with reference to several embodiments and the accompanying drawings. However, the examples are chosen only for the purpose of illustrating the invention and are not to be construed as limiting the scope of the invention.