Hydrophobic short-chain starch nanoparticles as well as preparation method and application thereof

Abstract

The invention relates to hydrophobic short-chain starch nanoparticles as well as a preparation method and application thereof, and belongs to the technical field of natural products. The invention provides a preparation method of hydrophobic short-chain starch nanoparticles, which comprises the following steps: mixing starch subjected to heat-moisture treatment with alpha-amylase, reacting at 30-40 DEG C and 180-220 rpm for 1-5 hours, and performing enzyme deactivation treatment to obtain starch subjected to enzymolysis; carrying out gelatinization treatment on the starch subjected to enzymolysis to obtain paste, carrying out reaction on the paste and pullulanase at 55-60 DEG C for 4-8 hours, and carrying out enzyme deactivation treatment to obtain short-chain starch; preparing the short-chain starch into short-chain starch nanoparticles by using an anti-solvent precipitation method; and esterifying the cross-linked short-chain starch nano-particles by using citric acid to obtain the hydrophobic short-chain starch nano-particles. Starch subjected to heat-moisture treatment is subjected to two-step enzymolysis to prepare short-chain starch, and the short-chain starch and citric acid are esterified and crosslinked through an anti-solvent precipitation method to prepare the short-chain starch nanoparticles with high hydrophobicity.

Description

Technical Field

[0001] This invention relates to the field of nanomaterials technology, and in particular to a hydrophobic short-chain starch nanoparticle, its preparation method, and its application. Background Technology

[0002] Starch, as a widely available, inexpensive, renewable, and biocompatible natural polymer, has broad application potential in food, medicine, chemical industry, and materials science. However, natural starch has limitations such as poor solubility, easy retrogradation, weak mechanical properties, and poor dispersibility in non-aqueous systems, which restrict its direct application in high-value-added fields.

[0003] To improve the functional properties of starch, nanotechnology has become an important research direction. Starch nanoparticles (SNPs) exhibit significant advantages in drug delivery systems, active ingredient encapsulation, composite material reinforcement, and biodegradable packaging due to their size effect, high specific surface area, and modifiability. Currently, the main methods for preparing starch nanoparticles include acid hydrolysis, enzymatic hydrolysis, mechanical fragmentation, and self-assembly.

[0004] Acid hydrolysis utilizes strong inorganic acids (such as hydrochloric acid and sulfuric acid) to hydrolyze starch below gelatinization temperature, destroying its amorphous regions to obtain nanoscale starch particles. This is a common preparation route. While widely used, traditional acid hydrolysis has inherent limitations that severely restrict the green and large-scale production of starch nanoparticles. The primary problem lies in its long reaction cycle, typically requiring several days of continuous heating. This not only leads to low production efficiency and significant energy consumption but also greatly increases production time and economic costs. More importantly, this method is extremely environmentally unfriendly, as the entire reaction system heavily relies on the use of large amounts of highly corrosive inorganic acids such as concentrated sulfuric acid and hydrochloric acid. These acids are difficult to recover effectively after the reaction and are ultimately discharged as high-salinity, high-acid wastewater, posing a severe pollution burden if not properly treated. Simultaneously, the harsh acidic conditions and prolonged reaction time easily lead to excessive degradation of starch molecular chains and unnecessary side reactions, affecting product quality stability. The harsh acid hydrolysis process excessively degrades starch molecular chains, resulting in insufficient strength in the formed nanoparticle structure. During encapsulation, storage, or digestion, this fragile structure is prone to disintegration, causing premature leakage of active substances.

[0005] The self-assembly method involves dissolving starch in a good solvent (such as DMSO or an alkaline solution), and then using an antisolvent (such as methanol or ethanol) to utilize the change in solubility to cause the starch molecular chains to re-aggregate and self-assemble into nanoparticles. After gelatinization, the linear and branched molecules of natural starch (especially common cereal starches) are fully hydrated and extended, forming a high-viscosity gel system. When this system undergoes antisolvent nano-sizing processes such as alcohol precipitation, the extremely high viscosity leads to the following problems: First, mass transfer efficiency is severely limited. The antisolvent cannot diffuse quickly and uniformly throughout the starch solution system, easily causing local concentrations that are too high or too low, resulting in nanoparticle aggregation or uneven formation. Second, to overcome the high viscosity and achieve uniform mixing, high-power, high-shear-force mechanical stirring equipment is required. This not only significantly increases the energy consumption per unit product but also directly drives up production costs due to increased equipment investment and maintenance costs, posing a major obstacle to the large-scale industrialization of the technology. The nanoparticle formation process based on the self-assembly principle is driven by the hydrogen bonding interactions between starch molecular chains, and the strength of this force is directly related to the molecular chain length. However, natural starch is a mixture of molecules with different chain lengths. Its broad and non-uniform chain length distribution leads to significant differences in the nucleation and growth kinetics of different molecules in the antisolvent. Specifically, short-chain molecules are highly mobile and tend to form small nuclei, while long-chain molecules easily entangle or randomly incorporate into crystal nuclei at different stages, resulting in nanoparticles with a wide particle size distribution, i.e., a high polydispersity index. This inherent structural inhomogeneity makes it difficult to achieve precise and repeatable control over the size and morphology of nanoparticles simply by adjusting process parameters, ultimately affecting batch-to-batch consistency and the stability of application performance. Due to the polydispersity of the product's particle size and internal structure, the encapsulation sites and interaction forces between different particles vary in strength. This leads to the non-specific release of encapsulated active substances at different rates during storage or digestion.

[0006] The starch nanoparticles prepared by the above method have a surface rich in hydroxyl groups, making them inherently highly hydrophilic. This characteristic results in extremely low affinity for hydrophobic active substances, leading to small loading capacity and poor encapsulation efficiency, which severely limits their application potential in the field of efficient delivery of hydrophobic active substances.

[0007] Therefore, there is an urgent need to develop starch nanoparticles with high encapsulation efficiency and high affinity for hydrophobic active substances. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide hydrophobic short-chain starch nanoparticles with strong loading capacity and high encapsulation efficiency for hydrophobic active substances, as well as their preparation method and application.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a method for preparing hydrophobic short-chain starch nanoparticles, comprising the following steps: S1. Mix the starch that has been treated with wet heat with α-amylase and react at 30-40℃ and 180-220rpm for 1-5h. After enzyme inactivation treatment, the enzymatically hydrolyzed starch is obtained. S2. The starch obtained from enzymatic hydrolysis in step S1 is gelatinized to obtain a paste. The paste is reacted with pullulanase at 55-60℃ for 4-8 hours. After enzyme inactivation treatment, short-chain starch is obtained. S3. The short-chain starch obtained in step S2 is prepared into short-chain starch nanoparticles by antisolvent precipitation. S4. Hydrophobic short-chain starch nanoparticles are obtained by using the short-chain starch nanoparticles obtained by citric acid esterification crosslinking step S3.

[0010] This invention prepares short-chain starch by two-step enzymatic hydrolysis of starch treated with wet heat, and obtains highly hydrophobic short-chain starch nanoparticles by cross-linking with citric acid esterification via antisolvent precipitation.

[0011] Compared to traditional methods for preparing starch nanoparticles, the enzymatic treatment of this invention avoids extreme conditions such as high temperature and high pressure, which typically require complex equipment, increasing production costs and operational difficulty. Simultaneously, enzymatic treatment also avoids the environmental pollution problems associated with acid hydrolysis in starch nanoparticle production. Acid hydrolysis not only requires large amounts of acidic reagents but also generates significant amounts of acidic wastewater, causing severe environmental pollution. Enzymatic treatment, on the other hand, uses biological enzymes as catalysts, conducting the reaction under mild conditions. This not only improves reaction selectivity and efficiency but also reduces the use of chemical reagents, lowering environmental risks during production and aligning with the requirements of green chemistry and sustainable development. Furthermore, this invention introduces a mild moist heat treatment step before enzymatic hydrolysis. This treatment, conducted below the gelatinization temperature, creates micropores within the starch granules without initiating gelatinization. These pores provide channels for α-amylase to enter the starch granules, enabling efficient enzymatic hydrolysis even in the ungelatinized state. This results in a more uniform and thorough hydrolysis process, further improving process efficiency and product consistency.

[0012] This invention uses citric acid, which has high biosafety, as a modifier, overcoming the residual risks and poor biocompatibility problems caused by the use of toxic reagents (such as acetic anhydride and long-chain acyl chlorides) in traditional hydrophobic modification, making the product more suitable for the food and pharmaceutical fields. Secondly, through the esterification and cross-linking effect of citric acid, while imparting good hydrophobicity to starch nanoparticles, their structural stability is enhanced, achieving a synergistic improvement in the encapsulation efficiency and loading capacity of hydrophobic active ingredients.

[0013] Furthermore, this invention solves the energy efficiency problem caused by high viscosity in traditional processes. By introducing non-gelatinized starch that has undergone wet heat treatment, the crystalline structure of starch granules is destroyed in advance without causing complete starch gelatinization and the accompanying high viscosity problem. This enhances the accessibility of enzyme reactions, thereby significantly reducing the mass transfer resistance and mechanical energy consumption in the subsequent enzymatic hydrolysis process, creating conditions for industrial low-energy production.

[0014] As a preferred embodiment of the preparation method of the present invention, in step S1, the wet heat treatment of the starch is specifically carried out as follows: the starch is mixed with water and then balanced to achieve a starch moisture content of 20-30%. The starch with a moisture content of 20-30% is heat-treated at 40-60℃ for 1.5-3 hours, dried until the moisture content is ≤10%, pulverized and sieved to obtain the wet heat-treated starch.

[0015] As a preferred embodiment of the preparation method of the present invention, in step S1, the wet heat treatment of the starch is specifically carried out as follows: the starch and water are mixed and balanced to make the moisture content of the starch reach 25%, the starch with a moisture content of 25% is heat-treated at 45-55℃ for 2 hours, dried to a moisture content of ≤10%, pulverized and sieved to obtain the wet heat-treated starch.

[0016] In a preferred embodiment of the preparation method of the present invention, in step S1, the starch treated with wet heat is mixed with 0.01 mM phosphate buffer to prepare a starch suspension, which is then mixed with α-amylase. The pH of the phosphate buffer is 5.0-6.5. Preferably, the pH of the phosphate buffer is 6.0.

[0017] As a preferred embodiment of the preparation method of the present invention, in step S1, the ratio of the heat-treated starch to the phosphate buffer is heat-treated starch: phosphate buffer = (15-25) g: 100 mL.

[0018] As a preferred embodiment of the preparation method of the present invention, in step S1, the ratio of the heat-treated starch to the phosphate buffer is heat-treated starch: phosphate buffer = 20g: 100mL.

[0019] In a preferred embodiment of the preparation method described in this invention, in step S1, the ratio of the hydrothermally treated starch to α-amylase is: hydrothermally treated starch : α-amylase = 1g dry weight : (15-35)U. This invention achieves precise control of starch molecular chain length by pretreating starch granules with α-amylase. This step effectively breaks down long chains, causing the starch nanoparticle chain length to be concentrated within a narrow range of polymerization degree 10-30. The resulting short-chain starch solution has a uniform structure, which fundamentally ensures that the nucleation and growth of the obtained nanoparticles tend to be consistent during the antisolvent precipitation process, ultimately producing short-chain starch nanoparticles with a highly concentrated size distribution (50-200 nm). This technical approach significantly improves the particle uniformity and batch-to-batch stability of the product, providing a structurally consistent and reliable basic material for encapsulating and delivering active substances.

[0020] In a preferred embodiment of the preparation method of the present invention, the ratio of the hydrothermally treated starch to α-amylase is 1 g dry weight: 20 U. The ratio of starch to α-amylase can also be at least one of 1 g dry weight: 25 U or 1 g dry weight: 30 U.

[0021] In a preferred embodiment of the preparation method of the present invention, in step S1, the enzyme inactivation treatment includes the following operations: the product obtained by reacting the moist heat-treated starch with α-amylase is transferred to a 100°C water bath and heated for 30 min for enzyme inactivation treatment. After cooling to 23-27°C, it is centrifuged at 8000×g for 15 min, the precipitate is collected, washed twice with deionized water, washed once with ethanol, dried, and ground to obtain the enzymatically hydrolyzed starch. Alternatively, the product obtained by reacting the moist heat-treated starch with α-amylase can also be subjected to enzyme inactivation treatment with a 70% v / v ethanol solution.

[0022] As a preferred embodiment of the preparation method of the present invention, in step S1, the reaction conditions are 35°C and 200 rpm for 2-4 hours.

[0023] In a preferred embodiment of the preparation method described in this invention, step S2 includes the following gelatinization process: the enzymatically hydrolyzed starch obtained in step S1 is mixed with 20 mM phosphate buffer and heated at 90-95°C for 30 min to obtain a paste; the pH value of the phosphate buffer is 5.5. The gelatinized starch (i.e., the paste) is generally transparent.

[0024] In a preferred embodiment of the preparation method of the present invention, the ratio of the enzymatically hydrolyzed starch to the phosphate buffer obtained in step S1 is 10g:90mL.

[0025] In a preferred embodiment of the preparation method of the present invention, in step S2, the ratio of enzymatically hydrolyzed starch to pullulanase obtained in step S1 is enzymatically hydrolyzed starch: pullulanase = 1g dry weight: (150-170) NPUN. The unit of pullulanase is NPUN, which refers to the amount of enzyme required to hydrolyze limit dextrin to produce 1 μmol of glucose per minute under the conditions of pH=6.5 and 60℃; the limit dextrin is the core structural fragment with branches remaining after amylopectin or glycogen is partially decomposed by a specific enzyme (i.e., containing α-(1-6) glycosidic bonds and / or β-(1-6) glycosidic bonds that cannot be cleaved by ordinary amylase).

[0026] This invention employs a synergistic enzymatic hydrolysis pretreatment process using α-amylase and pullulanase, which can efficiently and thoroughly decompose starch into the target short-chain structure. This treatment not only significantly increases the yield of short-chain starch nanoparticles from 20%-30% using traditional acid hydrolysis and alcohol precipitation methods to 40%-50%, greatly improving preparation efficiency, but also simultaneously optimizes the functional components of the product, increasing the proportion of resistant starch to 20%-30% (compared to 10-15% in traditional products) and increasing the content of slowly digestible starch.

[0027] As a preferred embodiment of the preparation method of the present invention, in step S2, the ratio of the enzymatically hydrolyzed starch to pullulanase obtained in step S1 is enzymatically hydrolyzed starch: pullulanase = 1g dry weight: 160NPUN.

[0028] In a preferred embodiment of the preparation method described in this invention, step S2 includes the following operation: the product obtained by reacting the paste with pullulanase is transferred to a 100°C water bath and heated for 30 min for enzyme inactivation. The supernatant obtained by centrifugation is the short-chain starch. To avoid impurity residue, the supernatant obtained by centrifugation can be filtered through a 0.45 μm pore size filter membrane. The preferred centrifugation conditions are 10000 × g for 10 min.

[0029] In a preferred embodiment of the preparation method described in this invention, step S3 includes the following steps: A1. Add the short-chain starch obtained in step S2 at 55-65℃ dropwise to anhydrous ethanol at a flow rate of 1-3 mL / min and a stirring speed of 180-220 rpm. After the addition is complete, stir at 180-220 rpm for 10 min, centrifuge at 10000×g for 10 min, and collect the precipitate. A2. The precipitate obtained in step A1 was washed twice with 70% v / v ethanol solution, resuspended in deionized water, and freeze-dried to obtain short-chain starch nanoparticles.

[0030] In a preferred embodiment of the preparation method described in this invention, in step A1, the volume ratio of short-chain starch to anhydrous ethanol is short-chain starch: anhydrous ethanol = 1:(1-5). To facilitate better precipitation of the short-chain starch nanoparticles, the volume of anhydrous ethanol is at least one times the volume of the short-chain starch.

[0031] In a preferred embodiment of the preparation method of the present invention, in step A1, the volume ratio of short-chain starch to anhydrous ethanol is short-chain starch: anhydrous ethanol = 1:3. Preferably, the volume ratio of short-chain starch to anhydrous ethanol can also be at least one of 1:2 and 1:4.

[0032] In a preferred embodiment of the preparation method of the present invention, in step S4, the citric acid esterification crosslinking includes the following steps: B1. Mix the citric acid alcohol solution with the short-chain starch nanoparticles obtained in step S3, and react at 23-27℃ for 10-14h. After the reaction is completed, remove the solvent to obtain product a. B2. Wash the product a obtained in step B1 with 55-65% v / v ethanol solution, centrifuge, take the supernatant, dry and grind it to obtain ground product a. React ground product a at 120-140℃ for 1.5-3h to obtain product b. B3. Wash the product b obtained in step B3 2-4 times with 90-100% v / v ethanol solution, dry it and pass it through a mesh sieve to obtain hydrophobic short-chain starch nanoparticles.

[0033] As a preferred embodiment of the preparation method of the present invention, in step B1, the ratio of citric acid in the citric acid alcohol solution to the short-chain starch nanoparticles obtained in step S3 is citric acid: short-chain starch nanoparticles = 1M: (1.5-2.5)g.

[0034] As a preferred embodiment of the preparation method of the present invention, in step B1, the ratio of citric acid in the citric acid alcohol solution to the short-chain starch nanoparticles obtained in step S3 is citric acid: short-chain starch nanoparticles = 1M: 2g.

[0035] In a preferred embodiment of the preparation method of the present invention, in step B1, the reaction conditions are a reaction at 25°C for 12 hours.

[0036] In a preferred embodiment of the preparation method described in this invention, in step B2, the concentration of the ethanol solution is 60% v / v.

[0037] In a preferred embodiment of the preparation method of the present invention, in step B2, the ground product a is reacted at 130°C for 2 hours.

[0038] In a preferred embodiment of the preparation method of the present invention, in step B3, the concentration of the ethanol solution is 95% v / v, and the number of washing cycles is 3.

[0039] In a preferred embodiment of the preparation method described in this invention, in step B3, the mesh size of the sieve is 380-420 mesh.

[0040] Secondly, the present invention provides hydrophobic short-chain starch nanoparticles, which are mainly prepared by the above-mentioned preparation method.

[0041] The hydrophobic short-chain starch nanoparticles obtained in this invention have been experimentally verified to have good hydrophobic properties and can effectively encapsulate hydrophobic active ingredients, thus serving as carriers for hydrophobic active ingredients.

[0042] In a preferred embodiment of the hydrophobic short-chain starch nanoparticles of the present invention, the number of short-chain molecules with a degree of polymerization of 6-36 accounts for 70-90% of the total number of molecular chains in the hydrophobic short-chain starch nanoparticles. That is, in the molecular chain population constituting the hydrophobic short-chain starch nanoparticles, 70-90% of the chain molecules (by number) have a degree of polymerization in the short-chain range of 6-36.

[0043] In a preferred embodiment of the hydrophobic short-chain starch nanoparticles of the present invention, the short-chain molecules with a degree of polymerization of 10-30 account for 40-100% of the short-chain molecules with a degree of polymerization of 6-36.

[0044] In a preferred embodiment of the hydrophobic short-chain starch nanoparticles of the present invention, the mass of resistant starch in the hydrophobic short-chain starch nanoparticles accounts for 10-30% of the total mass of the hydrophobic short-chain starch nanoparticles.

[0045] Thirdly, the present invention provides the application of the above-mentioned hydrophobic short-chain starch nanoparticles in the preparation of hydrophobic active substance encapsulation materials.

[0046] This invention encapsulates active substances with hydrophobic short-chain starch nanoparticles, significantly improving the stability and bioavailability of these substances. The encapsulated active substances experience less loss during storage and are better resistant to gastric acid in the digestive tract, ensuring their successful arrival in the intestines and effective absorption. This process not only extends the shelf life of the active substances but also improves their bioavailability in the human body, providing a new technological means for their widespread application in the pharmaceutical and healthcare fields.

[0047] Fourthly, this invention provides the application of the aforementioned hydrophobic short-chain starch nanoparticles in the preparation of a hydrophobic active substance delivery system. Experiments demonstrate that the active substance encapsulated by the hydrophobic short-chain starch nanoparticles maintains structural stability in an environment with pH < 7.0, and cleaves to release its contents in an environment with pH ≥ 7.0. This indicates that the delivery system prepared from the hydrophobic short-chain starch nanoparticles and the hydrophobic active substance can effectively penetrate the stomach, reach the intestines, and then release the hydrophobic active substance, targeting the intestines to exert its effects.

[0048] As a preferred embodiment of the application described in this invention, the hydrophobic active substance includes, but is not limited to, at least one of forsythoside, curcumin, magnolol, cannabidiol, succinate, quercetin, vitamin E, retinol, squalane, and jojoba seed oil.

[0049] Fifthly, the present invention provides a dermazone encapsulation compound comprising dermazone and the aforementioned hydrophobic short-chain starch nanoparticles, wherein the surface of the dermazone is coated with hydrophobic short-chain starch nanoparticles. By using hydrophobic short-chain starch nanoparticles as an encapsulation material, the present invention significantly improves the stability and bioavailability of dermazone.

[0050] In a preferred embodiment of the dermatin-encapsulated material of the present invention, the mass ratio of dermatin to hydrophobic short-chain starch nanoparticles is dermatin: hydrophobic short-chain starch nanoparticles = (1.2-6): 100.

[0051] Sixthly, the present invention provides a process for preparing the above-mentioned dermaton embedding material, comprising the following steps: (1) The above hydrophobic short-chain starch nanoparticles were dispersed in water to prepare a dispersion; (2) Prepare a dermatin alcohol solution by reacting dermatin with ethanol; (3) Add the quercetin alcohol solution obtained in step (2) to the dispersion obtained in step (1), stir for 0.5-1.5h, remove ethanol, dry, and obtain quercetin embedding material.

[0052] This invention fundamentally solves the bottlenecks of low loading and poor stability in physical embedding by enhancing the interfacial affinity with hydrophobic active substances.

[0053] As a preferred embodiment of the preparation process described in this invention, the mass ratio of hydrophobic short-chain starch nanoparticles in the dispersion to quercetin in the quercetin alcohol solution is quercetin: hydrophobic short-chain starch nanoparticles = (1.2-6): 100.

[0054] In a preferred embodiment of the preparation method of the present invention, in step (1), the stirring speed is 400-600 rpm and the stirring time is 1 hour. Preferably, stirring is carried out under light-protected conditions to avoid decomposition of dermatin.

[0055] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention prepares short-chain starch by two-step enzymatic hydrolysis of starch treated with wet heat, and then prepares highly hydrophobic short-chain starch nanoparticles by antisolvent precipitation and citric acid esterification crosslinking. This preparation method solves the key problems of poor loading capacity and low encapsulation efficiency of hydrophobic active substances due to strong hydrophilicity by synergistically regulating the surface and bulk structure of starch nanoparticles; and at the same time overcomes the defects of fragile particle structure and insufficient stability of particles prepared by acid hydrolysis, and the defects of non-specific burst release of active substances caused by uneven particle size of particles prepared by self-assembly method.

[0056] (2) This invention employs a synergistic enzymatic hydrolysis pretreatment process using α-amylase and pullulanase, which can efficiently and thoroughly decompose starch into the target short-chain structure. First, α-amylase is used to cleave α-1,4 glycosidic bonds to reduce the degree of polymerization, and then pullulanase is used to further regulate the chain length distribution by α-1,6 glycosidic bonds, thereby obtaining short-chain components with a concentrated degree of polymerization (DP 10-30), providing precursor materials for the self-assembly preparation of nanoparticles with uniform particle size and consistent batch-to-batch consistency.

[0057] (3) This invention encapsulates active substances with hydrophobic short-chain starch nanoparticles, significantly improving the stability and bioavailability of the active substances. The encapsulated active substances experience less loss during storage and are better resistant to gastric acid in the digestive tract, ensuring their smooth arrival in the intestines and effective absorption. This process not only extends the shelf life of the active substances but also improves their bioavailability in the human body, providing a new technical means for their widespread application in the pharmaceutical and healthcare fields.

[0058] (4) The present invention uses hydrophobic short-chain starch nanoparticles as encapsulation material to encapsulate dermatin, thereby significantly improving the stability and bioavailability of dermatin. Attached Figure Description

[0059] Figure 1 Scanning electron microscope images of different short-chain starch nanoparticles in Example 1 of the present invention; Figure 2 The percentage of short-chain molecules with a degree of polymerization of 10-30 in different short-chain starch nanoparticles in Example 1 of the present invention; Figure 3 The results of the ratio determination of resistant starch, slow-digesting starch and fast-digesting starch in different starches and short-chain starch nanoparticles in Example 1 of the present invention; Figure 4 The results of hydrophilicity and hydrophobicity tests on different short-chain starch nanoparticles and hydrophobic short-chain starch nanoparticles in Example 1 of the present invention are shown. Figure 5 The above are the statistical results of starch yield after different enzymatic hydrolysis in Example 1 of the present invention; Figure 6 The statistical results of the degree of substitution of different hydrophobic short-chain starch nanoparticles in Example 1 of the present invention; Figure 7 The test results show the effect of different substrates on the recovery rate of hydrophobic active substances in Example 2 of the present invention. Figure 8 The results of measuring the release of quercetin from different quercetin-encapsulated materials in vitro under simulated digestion in Example 3 of the present invention; Figure 9 The results of the determination of the antioxidant activity of free quercetin after simulated digestion in vitro for different quercetin embeddings in Effect 3 of the present invention; Figure 10 The results of the antioxidant assay of free quercetin after simulated digestion in vitro for different quercetin embeddings in Effect 3 of the present invention; In the above figure, the appearance of different lowercase letters between the two groups within the same indicator indicates that there is a significant difference between the two groups (p < 0.05). Detailed Implementation

[0060] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0061] Unless otherwise specified, all other materials and reagents used in the examples, comparative examples, and effect examples are commercially available.

[0062] The CAS number of the dermatin used in the following examples, comparative examples, and effect examples is 520-33-2, and its structural formula is [insert structural formula here]. .

[0063] In the following examples, comparative examples, and effect examples, the phosphate buffer (hereinafter referred to as PBS) mainly consists of Na2HPO4, KH2PO4, NaCl, and KCl, and the corresponding finished products can be purchased from commercial channels.

[0064] In the following examples, comparative examples, and effect examples, the α-amylase is an α-amylase derived from Bacillus amyloliquefaciens.

[0065] The unit of pullulanase described below is NPUN, which refers to the amount of enzyme required to hydrolyze limit dextrin to produce 1 μmol of glucose per minute under the conditions of pH=6.5 and 60℃; the limit dextrin is the core structural fragment with branches remaining after amylopectin or glycogen is partially decomposed by a specific enzyme (i.e., containing α-(1-6) glycosidic bonds and / or β-(1-6) glycosidic bonds that cannot be cut by ordinary amylase).

[0066] Example 1 This embodiment provides hydrophobic short-chain starch nanoparticles and their preparation method, the preparation method comprising the following steps: 1.1 Place 20g of glutinous rice starch in a sealed container, mix it with water and equilibrate it so that the starch moisture content reaches 25%. Heat treat it at 60℃ for 2 hours, dry it in an oven at 40℃ for 24 hours (at this time, the starch moisture content is ≤10%), pulverize it and pass it through a 100-mesh sieve to obtain starch that has undergone wet heat treatment. 1.2 Disperse 20g of the hydrothermally treated starch obtained in step 1.1 in 100mL of 0.01mM PBS with pH=6.0 to obtain a starch suspension; 1.3 The starch suspension obtained in step 1.2 was mixed with 400U of α-amylase (at this time, the ratio of starch to α-amylase in the starch suspension was starch: α-amylase = 1g dry weight: 20U). The mixture was reacted at 35℃ and 200rpm for 4h. After cooling to 25℃, the mixture was centrifuged at 8000×g for 15min. The precipitate was collected, and the enzyme was inactivated with 70% v / v ethanol solution. The precipitate was washed twice with deionized water and once with anhydrous ethanol. The mixture was dried in an oven at 40℃ for 24h and ground into powder to obtain the enzymatically hydrolyzed starch. 1.4 Mix 10g of the enzymatically hydrolyzed starch obtained in step 1.3 with 90mL of 20mM PBS (pH=5.5) and heat in a 90℃ water bath for 30min to obtain a paste. 1.5 Following the ratio of starch to pullulanase in the paste as starch:pullulanase = 1g dry weight: 160NPUN, the paste obtained in step 1.4 was mixed with pullulanase and enzymatically hydrolyzed at 60℃ and 200rpm for 8h. The resulting product was then transferred to a 100℃ water bath and heated for 30min to inactivate the enzyme. After cooling to 25℃, it was centrifuged at 10000×g for 10min. The supernatant was then filtered through a 0.45μm filter membrane to obtain short-chain starch. 1.6 Following the volume ratio of short-chain starch obtained in step 1.5 to anhydrous ethanol of 1:1, the short-chain starch obtained in step 1.5 at 60℃ was added dropwise to anhydrous ethanol at a flow rate of 2 mL / min and a stirring speed of 200 rpm. After the addition was complete, the mixture was stirred at 200 rpm for 10 min and centrifuged at 10000×g for 10 min to collect the precipitate. 1.7 The precipitate obtained in step 1.6 was washed twice with 70% v / v ethanol solution, resuspended in deionized water, and freeze-dried to obtain short-chain starch nanoparticles. 1.8 The citric acid ethanol solution was mixed with the short-chain starch nanoparticles obtained in step 1.7 according to the ratio of citric acid to short-chain starch nanoparticles in the citric acid ethanol solution as citric acid: short-chain starch nanoparticles = 1M: 2.5g. The mixture was reacted at 25℃ for 12h. After the reaction was completed, the ethanol was removed by vacuum concentration at 45℃ to obtain product a. 1.9 Wash the product a obtained in step 1.8 with 60% v / v ethanol solution, centrifuge to collect the precipitate, dry and grind it to obtain ground product a, and react the ground product a at 130℃ for 2h to obtain product b; 1.10 The product b obtained in step 1.9 was washed three times with 95% v / v ethanol solution, dried, and passed through a 400-mesh sieve to obtain hydrophobic short-chain starch nanoparticles.

[0067] The short-chain starch nanoparticles obtained in step 1.7 are designated as SCSNP-4h, and the hydrophobic short-chain starch nanoparticles obtained in step 1.10 are designated as M. SCSNP-4h.

[0068] Example 2 This embodiment provides hydrophobic short-chain starch nanoparticles and their preparation method. The preparation method is similar to that of Example 1, except that in step 1.3, the α-amylase reaction time is adjusted to 2 hours, while the remaining steps and parameters remain unchanged. The short-chain starch nanoparticles obtained in step 1.7 are designated as SCSNP-2h, and the hydrophobic short-chain starch nanoparticles obtained in step 1.10 are designated as M. SCSNP-2h.

[0069] Example 3 This embodiment provides hydrophobic short-chain starch nanoparticles and their preparation method. The preparation method is similar to that in Example 1, except that: In step 1.3, the amount of α-amylase used is 300U. At this time, the ratio of starch to α-amylase in the starch suspension is starch: α-amylase = 1g dry weight: 15U. The reaction is carried out at 30℃ and 220rpm for 2h. The remaining steps and parameters remain unchanged.

[0070] Example 4 This embodiment provides hydrophobic short-chain starch nanoparticles and their preparation method. The preparation method is similar to that in Example 1, except that: In step 1.3, the amount of α-amylase used is 700U. At this time, the ratio of starch to α-amylase in the starch suspension is starch: α-amylase = 1g dry weight: 35U. The reaction is carried out at 40℃ and 180rpm for 2h. The remaining steps and parameters remain unchanged.

[0071] Example 5 This embodiment provides hydrophobic short-chain starch nanoparticles and their preparation method. The preparation method is similar to that in Example 1, except that: In step 1.5, the starch:pullulanase = 1g dry weight: 150NPUN, and the enzyme is hydrolyzed at 55℃ and 200rpm for 8h. The remaining steps and parameters remain unchanged.

[0072] Example 6 This embodiment provides hydrophobic short-chain starch nanoparticles and their preparation method. The preparation method is similar to that in Example 1, except that: In step 1.5, the starch:pullulanase = 1g dry weight: 170NPUN, and the enzyme is hydrolyzed at 58℃ and 200rpm for 8h. The remaining steps and parameters remain unchanged.

[0073] Example 7 This embodiment provides hydrophobic short-chain starch nanoparticles and their preparation method. The preparation method is similar to that in Example 1, except that: In step 1.8, the ratio of citric acid to short-chain starch nanoparticles in the citric acid ethanol solution is citric acid: short-chain starch nanoparticles = 1M: 1.5g. The reaction is carried out at 27°C for 10h, and the remaining steps and parameters remain unchanged.

[0074] Example 8 This embodiment provides hydrophobic short-chain starch nanoparticles and their preparation method. The preparation method is similar to that in Example 1, except that: In step 1.8, the ratio of citric acid to short-chain starch nanoparticles in the citric acid ethanol solution is citric acid: short-chain starch nanoparticles = 1M: 1g. The reaction is carried out at 23°C for 14 hours, and the remaining steps and parameters remain unchanged.

[0075] Example 9 This embodiment provides hydrophobic short-chain starch nanoparticles and their preparation method. The preparation method is similar to that in Example 1, except that: In step 1.1, the starch has a moisture content of 20% before heat treatment and is heat-treated at 40°C for 3 hours; In step 1.2, the amount of starch obtained in step 1.1 after wet heat treatment is adjusted to 15g; In step 1.6, the volume ratio of short-chain starch obtained in step 1.5 to anhydrous ethanol is short-chain starch: anhydrous ethanol = 1:5. The temperature of the short-chain starch obtained in step 1.5 is 55℃, the flow rate is 1mL / min, the stirring speed is 180rpm, and the stirring speed after the addition is complete is 180rpm. In step 1.9, the ground product a is reacted at 120°C for 3 hours; The remaining steps and their parameters remain unchanged.

[0076] Example 10 This embodiment provides hydrophobic short-chain starch nanoparticles and their preparation method. The preparation method is similar to that in Example 1, except that: In step 1.1, the starch has a moisture content of 30% before heat treatment and is heat-treated at 60°C for 1.5 hours; In step 1.2, the amount of starch obtained in step 1.1 after wet heat treatment is adjusted to 25g; In step 1.6, the volume ratio of short-chain starch obtained in step 1.5 to anhydrous ethanol is short-chain starch: anhydrous ethanol = 1:3. The temperature of the short-chain starch obtained in step 1.5 is 65℃, the flow rate is 3mL / min, the stirring speed is 220rpm, and the stirring speed after the addition is complete is 220rpm. In step 1.9, the ground product a is reacted at 140°C for 1.5 h; The remaining steps and their parameters remain unchanged.

[0077] Example 11 This embodiment provides a dermosiderin embedding material and its preparation process, which includes the following steps: 2.1 Disperse 5 mg of the hydrophobic short-chain starch nanoparticles (M.SCSNP-4h) obtained in Example 1 in water to prepare a dispersion; 2.2 Prepare a 300 μg / mL quercetin alcohol solution by mixing quercetin with ethanol; 2.3 The quercetin alcohol solution obtained in step 2.2 was added dropwise to the dispersion obtained in step 2.1 (at this time, quercetin: hydrophobic short-chain starch nanoparticles = 6:100, mass ratio), stirred at 200 rpm for 0.5 h, ethanol was removed using a nitrogen concentrator, freeze-dried for 48 h, and ground to obtain quercetin encapsulated material.

[0078] Example 12 This embodiment provides a dermosin embedding material and its preparation process. The preparation process is similar to that of Example 11, except that: In step 2.1, the hydrophobic short-chain starch nanoparticles (M.SCSNP-4h) obtained in Example 1 are replaced with the hydrophobic short-chain starch nanoparticles (M.SCSNP-2h) obtained in Example 2, while the remaining steps and parameters remain unchanged.

[0079] Example 13 This embodiment provides a dermosin embedding material and its preparation process. The preparation process is similar to that of Example 11, except that: In step 2.1, the amount of hydrophobic short-chain starch nanoparticles (M.SCSNP-4h) obtained in Example 1 is 25 mg, and the ratio of dermatin to hydrophobic short-chain starch nanoparticles is 1.2:100 (mass ratio), while the remaining steps and parameters remain unchanged.

[0080] Comparative Example 1 This comparative example provides hydrophobic short-chain starch nanoparticles and their preparation method. The preparation method is similar to that of Example 1, except that α-amylase hydrolysis is not performed. The details are as follows: 3.1 The starch that has undergone hydrothermal treatment was prepared according to step 1.1 of Example 1; 3.2 Mix 10g of the hydrothermally treated starch obtained in step 3.1 with 90mL of 20mM PBS (pH=5.5) and heat in a 90℃ water bath for 30min to obtain a paste. 3.3 The starch and pullulanase obtained in step 1.4 were mixed with pullulanase according to the ratio of starch to pullulanase in the paste after wet heat treatment as starch: pullulanase = 1g dry weight: 160 NPUN. The mixture was enzymatically hydrolyzed at 60℃ and 200rpm for 8h. The product was then transferred to a 100℃ water bath and heated for 30min to inactivate the enzyme. After cooling to 25℃, the mixture was centrifuged at 10000×g for 10min. The supernatant was then filtered through a filter membrane with a pore size of 0.45μm to obtain short-chain starch. 3.4 Short-chain starch nanoparticles were prepared according to steps 1.6-1.7 of Example 1; 3.5 Hydrophobic short-chain starch nanoparticles were prepared according to steps 1.8-1.10 of Example 1.

[0081] The short-chain starch nanoparticles obtained in step 3.4 are denoted as SCSNP, and the hydrophobic short-chain starch nanoparticles obtained in step 3.5 are denoted as M.SCSNP.

[0082] Comparative Examples 2-5 Comparative Examples 2-5 provide a dermal filler and its preparation process, respectively. The preparation process is similar to that of Example 11, except that the hydrophobic short-chain starch nanoparticles in the dispersion obtained in step 2.1 are different, as shown in Table 1. The remaining steps and parameters remain unchanged.

[0083] Table 1. Types of short-chain starch nanoparticles in different dispersions Comparative Example 6 This comparative example provides hydrophobic short-chain starch nanoparticles and their preparation method. The preparation method is similar to that in Example 1, except that: In step 1.3, the amount of α-amylase used is 1000U. At this time, the ratio of starch to α-amylase in the starch suspension is starch: α-amylase = 1g dry weight: 50U. The remaining steps and their parameters remain unchanged.

[0084] Comparative Example 7 This comparative example provides hydrophobic short-chain starch nanoparticles and their preparation method. The preparation method is similar to that in Example 1, except that: In step 1.5, the starch:pullulanase = 1g dry weight: 50NPUN, and the remaining steps and parameters remain unchanged.

[0085] Comparative Example 8 This comparative example provides hydrophobic short-chain starch nanoparticles and their preparation method. The preparation method is similar to that in Example 1, except that: In step 1.8, the ratio of citric acid to short-chain starch nanoparticles in the citric acid ethanol solution is citric acid: short-chain starch nanoparticles = 1M: 5g, and the remaining steps and parameters remain unchanged.

[0086] Example 1 The short-chain starch nanoparticles were characterized using the following specific method: 1. The morphology of short-chain starch nanoparticles (SCSNP of Comparative Example 1, SCSNP-4h of Example 1, SCSNP-2h of Example 2, and hydrophobic short-chain starch nanoparticles of Comparative Example 7) was analyzed using scanning electron microscopy. The short-chain starch nanoparticles were fixed on the sample stage with double-sided conductive adhesive and a thin gold film was deposited on the surface. The accelerating voltage was set to 3 kV. The results are as follows: Figure 1 As shown, after treatment with α-amylase, the short-chain starch nanoparticles SCSNP, SCSNP-2H, SCSNP-4h, and those from Examples 5 and 6 exhibited more uniform morphology and smaller size. The nanoparticles obtained in Comparative Example 7, due to insufficient α-(1-6) glycosidic bond scission, could not form short-chain starch nanoparticles after antisolvent precipitation. This indicates that only with a specific pullulanase dosage can the α-(1-6) glycosidic bonds of starch be completely broken, yielding more short-chain starch nanoparticles.

[0087] 2. The chain length distribution of glutinous rice starch and short-chain starch nanoparticles (SCSNP of Comparative Example 1, SCSNP-4h of Example 1, and SCSNP-2h of Example 2) was determined by high-performance anion exchange chromatography (HPAEC, Dionex ICS-6000 SP, Thermo Fisher Scientific). Chromatographic separation was performed using a CarboPac PA-100 column (250 mm × 4 mm) at a flow rate of 1 mL / min with 150 mmol / L NaOH (elution A) and 150 mmol / L NaOH containing 1 mol / L sodium acetate (elution buffer B). The results are as follows: Figure 2 As shown, the chain lengths of glutinous rice starch and SCSNPs are mainly concentrated between the degree of polymerization (DP) of 10-30, accounting for more than 60%. After hydrolysis by α-amylase, the proportion of short chains in this range (DP 10-30) further increases, indicating that α-amylase hydrolysis can effectively increase the content of short-chain starch, thereby increasing the yield of short-chain starch nanoparticles.

[0088] 3. Determination of the contents of rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) in glutinous rice starch, the enzymatically hydrolyzed starch obtained in step 1.3 of Examples 1-2, SCSNP of Comparative Example 1, SCSNP-4h of Example 1, and SCSNP-2h of Example 2. 200 mg of sample was dispersed in 15 mL of sodium acetate buffer (0.1 M, pH=5.2), and 5 mL of enzyme mixture (containing porcine pancreatic α-amylase and amyloglucosidase) was added. The mixture was hydrolyzed by shaking in a 37°C water bath. 1 mL of the hydrolysate was collected at 20 min and 120 min, respectively, and the enzymes were inactivated by boiling in a water bath for 10 min. After centrifugation, the supernatant was collected, and the reducing sugar content was determined using the 3,5-dinitrosalicylic acid (DNS) method. The results are shown in [Figure 1]. Figure 3 Calculate the content of each component using the following formulas 1-3: Equation 1 Equation 2 Equation 3 In Equations 1 and 2, G20 and G120 represent the glucose mass (mg) released after hydrolysis for 20 min and 120 min, respectively, TS represents the total starch mass in the sample, and 0.9 is the conversion factor from glucose to starch.

[0089] like Figure 3 As shown, compared with glutinous rice starch and starch treated with α-amylase, the contents of resistant starch (RS) and slow-digesting starch (SDS) in short-chain starch nanoparticles (SCSNP, SCSNP-2h, and SCSNP-4h) were significantly increased (p < 0.05). Furthermore, the content of slow-digesting starch (SDS) in short-chain starch nanoparticles treated with α-amylase also showed a further increasing trend. These results indicate that short-chain starch nanoparticles treated with α-amylase have higher stability.

[0090] 4. The surface polarity of short-chain starch nanoparticles and citric acid-modified short-chain starch nanoparticles was determined using a two-phase partition method: 1 g of sample was dispersed in a mixture of 2 mL water (polar phase) and 2 mL dichloromethane (non-polar phase, density 1.335 g / mL), vortexed for 3 minutes, and then allowed to stand at 25 °C to separate into layers. Solvent affinity was determined by observing the distribution behavior of SCSNP, SCSNP-2h, SCSNP-4h, M.SCSNP-2h, and M.SCSNP-4h after phase separation. Figure 4As shown, the short-chain starch nanoparticles modified with citric acid exhibit obvious amphiphilicity, and this amphiphilic characteristic is further enhanced with the extension of α-amylase pretreatment time, indicating that the hydrophobic short-chain starch nanoparticles of the present invention have stronger hydrophobicity, providing a basis for encapsulating hydrophobic active substances.

[0091] 5. The hydrophobic short-chain starch nanoparticles obtained in Examples 1 and 3-4 and the hydrophobic short-chain starch nanoparticles obtained in Comparative Example 6 were respectively subjected to freeze-drying treatment. After weighing, the yield was calculated according to Formula 4 below. The results are shown in [Figure 4]. Figure 5 : Yield (%) = W_SCSNP / W × 100%…………………………………………Equation 4 In Equation 4, W_SNP is the mass of the obtained SCSNP, and W is the mass of the raw material.

[0092] like Figure 5 As shown, excessive α-amylase will cause the starch molecule backbone to be over-degraded, destroying the short-chain molecular chains necessary for the formation of nanoparticles and forming too much soluble oligosaccharide, thus leading to a significant decrease in the yield of starch nanoparticles. This indicates that starch treated with wet heat must be processed within a specific range of α-amylase dosage in order to obtain ideal short-chain starch particles.

[0093] 6. The degree of substitution of the hydrophobic short-chain starch nanoparticles obtained in Example 1 and the hydrophobic short-chain starch nanoparticles obtained in Comparative Example 8 was measured. Specifically, 0.5 g of hydrophobic short-chain starch nanoparticles or the short-chain starch nanoparticles obtained in step 1.7 were weighed into a 250 mL Erlenmeyer flask, 20 mL of deionized water and a few drops of phenolphthalein indicator were added, and the free citric acid was titrated with 0.1 M NaOH until a faint red color was obtained. Then 25 mL of 0.5 M NaOH was added, and the reaction was carried out at room temperature for 60 min. The excess alkali was back-titrated with 0.5 M HCl, and the degree of substitution (DS) was calculated according to the following formulas 5-6. The results are shown in [Figure 1]. Figure 6 : Equation 5 Equation 6 In Formulas 5 and 6, A is the percentage of esterified carboxyl groups (%), M is the molar mass of citric acid substituents (175 g / mol), m is the sample mass (mg), c is the HCl concentration (0.5M), V0 is the volume of HCl consumed by the blank sample (short-chain starch nanoparticles) (mL), and V1 is the volume of HCl consumed by the modified sample (hydrophobic short-chain starch nanoparticles) (mL).

[0094] like Figure 6As shown, the addition of 2M citric acid can significantly increase the degree of substitution of short-chain starch nanoparticles, thereby improving the hydrophobic properties of short-chain starch nanoparticles and enabling them to better combine with hydrophobic active substances to obtain short-chain starch nanoparticles with higher hydrophobicity.

[0095] Example 2 The effect of different types and amounts of short-chain starch nanoparticles on the recovery rate of quercetin in quercetin-encapsulated materials was evaluated by setting the same content of quercetin.

[0096] First, SCSNP, SCSNP-2h, SCSNP-4h, M.SCSNP-2h, and M.SCSNP-4h were used as substrates, and dermosin embeddings with a content of 300 μg were prepared by adjusting the amount of substrates (5 mg, 10 mg, 15 mg, 20 mg, and 25 mg). The preparation process was carried out in accordance with Example 11.

[0097] Next, 5 mg of the above-mentioned quercetin-embedded sample was taken and dispersed in 1 mL of ethanol, vortexed for 5 min, and then centrifuged at 2000×g for 10 min. The remaining precipitate was resuspended in 1 mL of ethanol, sonicated at 50℃ for 30 min, and centrifuged again. The supernatant from the second treatment was used to determine the content of quercetin embedded in the matrix.

[0098] The concentration of dermaclofen was determined by high-performance liquid chromatography (HPLC). Chromatographic analysis was performed using an Agilent 1220 Infinity II system equipped with a diode array detector. The chromatographic column was a Shim-pack GIS C18 column (4.6 × 250 mm, 5 μm), and the column temperature was 25 °C. The mobile phase was methanol-water (80:20, v / v). The content was determined according to the external standard method, and the results are shown in the table below. Figure 7 .

[0099] The recovery rate of quercetin in short-chain starch nanoparticles was calculated using the following formula 7: Recovery rate (%) = ………………………Equation 7 like Figure 7 As shown, the recovery rate of quercetin in the matrix of short-chain starch nanoparticles (M.SCSNP, M.SCSNP-2h, M.SCSNP-4h) modified with citric acid was significantly higher than that of the unmodified samples (p < 0.05). After pretreatment with α-amylase, the starch nanoparticles, due to their higher specific surface area, underwent more thorough modification, thereby further improving the binding capacity of the matrix to quercetin.

[0100] Example 3 To evaluate the quercetin release effect of the quercetin embeddings obtained in Examples 11-12 and Comparative Examples 2-5 in animals, the release effect of quercetin was detected by establishing an INFOGEST static in vitro gastrointestinal digestion model. The specific scheme is as follows: The dermosin-encapsulated materials obtained in Examples 11-12 and Comparative Examples 2-5 were used as test samples.

[0101] 1. An INFOGEST static in vitro gastrointestinal digestion model was constructed based on the following references. The quercetin content after each digestion stage was determined by high-performance liquid chromatography (HPLC) using quercetin concentration. The results are shown below. Figure 8 .

[0102] Reference: INFOGEST static in vitro simulation of gastrointestinal fooddigestion[J].Nature Protocols, 2019.DOI:10.1038 / s41596-018-0119-1. like Figure 8 As shown, citric acid-modified short-chain starch nanoparticles can effectively protect hesperidin during gastric acid digestion and deliver it to the intestinal environment for release. Furthermore, samples pretreated with α-amylase exhibit a higher hesperidin binding rate, resulting in a further increase in the amount of hesperidin released during digestion.

[0103] 2. The antioxidant activity of free quercetin after in vitro digestion was analyzed using the DPPH (1,1-diphenyl-2-trinitrophenylhydrazine) and ABTS (2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)) free radical scavenging capacity assay. A standard curve was constructed using water-soluble vitamin E as a standard. The results are expressed as the equivalent amount of water-soluble vitamin E (μg TE / mg quercetin) per mg of embedded quercetin, i.e., how many μg of water-soluble vitamin E has the antioxidant effect equivalent to each mg of embedded quercetin. For example, a value of 40 is assumed to mean that each mg of embedded quercetin has the antioxidant effect equivalent to 40 μg of water-soluble vitamin E after simulated digestion. The above results are shown in […]. Figure 9-10 And Table 2.

[0104] Table 2. Results of antioxidant activity determination of free quercetin after different quercetin embeddings in an in vitro gastrointestinal digestion model (x̅±SD). like Figure 9-10As shown in Table 2, the synergistic effect of α-amylase pretreatment and citric acid modification significantly improved the retention and delivery efficiency of the antioxidant activity of the encapsulated quercetin after digestion. Specifically, the citric acid-modified carrier group (M.SCSNP-4h) pretreated with α-amylase for 4 hours showed the highest free radical scavenging rate after digestion, and its antioxidant activity recovery level was significantly better than that of the unmodified carrier (SCSNP-4h), the unmodified carrier (M.SCSNP), and other combinations with shorter treatment times (such as M.SCSNP-2h). This data directly demonstrates that α-amylase pretreatment optimizes the carrier structure, laying the foundation for the subsequent construction of a stable, pH-responsive cross-linked network using citric acid. This synergistic system not only more effectively protects quercetin from degradation during digestion but also ensures that it functions in a highly active form during targeted release into the intestine.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing hydrophobic short-chain starch nanoparticles, characterized in that, Includes the following steps: S1. Mix the starch that has been treated with wet heat with α-amylase and react at 30-40℃ and 180-220rpm for 1-5h. After enzyme inactivation treatment, the enzymatically hydrolyzed starch is obtained. S2. The starch obtained from enzymatic hydrolysis in step S1 is gelatinized to obtain a paste. The paste is reacted with pullulanase at 55-60℃ for 4-8 hours. After enzyme inactivation treatment, short-chain starch is obtained. S3. The short-chain starch obtained in step S2 is prepared into short-chain starch nanoparticles by antisolvent precipitation. S4. Hydrophobic short-chain starch nanoparticles are obtained by using the short-chain starch nanoparticles obtained by citric acid esterification crosslinking step S3.

2. The preparation method according to claim 1, characterized in that, Includes at least one of (I)-(II): (I) In step S1, the ratio of the wet-heat treated starch to α-amylase is wet-heat treated starch: α-amylase = 1g dry weight: (15-35)U; (II) In step S2, the ratio of the enzymatically hydrolyzed starch to pullulanase obtained in step S1 is: enzymatically hydrolyzed starch: pullulanase = 1g dry weight: (150-170) NPUN.

3. The preparation method according to claim 1, characterized in that, In step S4, the citric acid esterification crosslinking includes the following steps: B1. Mix the citric acid alcohol solution with the short-chain starch nanoparticles obtained in step S3, and react at 23-27℃ for 10-14h. After the reaction is completed, remove the solvent to obtain product a. B2. Wash the product a obtained in step B1 with 55-65% v / v ethanol solution, centrifuge, take the supernatant, dry and grind it to obtain ground product a. React ground product a at 120-140℃ for 1.5-3h to obtain product b. B3. Wash the product b obtained in step B3 2-4 times with 90-100% v / v ethanol solution, dry it and pass it through a 380-420 mesh sieve to obtain hydrophobic short-chain starch nanoparticles.

4. The preparation method according to claim 3, characterized in that, In step B1, the ratio of citric acid in the citric acid alcohol solution to the short-chain starch nanoparticles obtained in step S3 is citric acid: short-chain starch nanoparticles = 1M: (1.5-2.5)g.

5. A hydrophobic short-chain starch nanoparticle, characterized in that, It is mainly prepared by the preparation method described in any one of claims 1-4.

6. The application of the hydrophobic short-chain starch nanoparticles as described in claim 5 in the preparation of hydrophobic active substance encapsulation materials.

7. The application of the hydrophobic short-chain starch nanoparticles as described in claim 5 in the preparation of a hydrophobic active substance delivery system.

8. A dermatin embedding material, characterized in that, It includes quercetin and the aforementioned hydrophobic short-chain starch nanoparticles, wherein the surface of the quercetin is coated with hydrophobic short-chain starch nanoparticles.

9. The dermatin embedding material as described in claim 8, characterized in that, The mass ratio of dermatin to hydrophobic short-chain starch nanoparticles is dermatin:hydrophobic short-chain starch nanoparticles = (1.2-6):

100.

10. A process for preparing a dermosiderin embedding material, characterized in that, Includes the following steps: (1) The above hydrophobic short-chain starch nanoparticles were dispersed in water to prepare a dispersion; (2) Prepare a dermatin alcohol solution by reacting dermatin with ethanol; (3) Add the quercetin alcohol solution obtained in step (2) to the dispersion obtained in step (1), stir for 0.5-1.5h, remove ethanol, dry, and obtain quercetin embedding material.

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