Preparation method and application of drug sustained-release modified starch hydrogel

Abstract

The invention discloses a preparation method and application of drug sustained-release modified starch hydrogel, and belongs to the field of starch chemical modification and biomedical materials. The method comprises the following steps: firstly, preparing a CTS-PEG-600 composite solution and a PAA micelle modified starch dispersion liquid by virtue of a PAA micelle mediated starch hydroxyl modification and starch gelatinization-network interweaving synergistic enhancement strategy, constructing a compact three-dimensional network by virtue of composite crosslinking and high-temperature gelatinization, and carrying out post-treatment, so as to obtain the starch-based hydrogel material. After the hydrogel is loaded with fucoidin, the hydrogel can be prepared into an oral sustained-release preparation, long-acting stable release of drugs and targeted therapy of non-alcoholic fatty liver diseases are achieved, the hydrogel has excellent biocompatibility, mechanical stability and sustained-release controllability, the process is green and environmentally friendly, and the hydrogel is suitable for large-scale production and wide in application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of starch chemical modification and biomedical materials, and in particular to a preparation method of a drug release modified starch hydrogel and application thereof. BACKGROUND

[0002] As a kind of three-dimensional network material formed by physical or chemical cross-linking of hydrophilic polymer chains, hydrogel occupies a core position in the fields of drug release, tissue engineering scaffolds, wound dressings and other biomedical fields due to its high water content, softness similar to human tissue and excellent biocompatibility. In recent years, hydrogel materials based on natural polymers have gradually replaced some synthetic polymer hydrogels as research hotspots due to their biodegradability and non-immunogenicity. Among them, starch-based hydrogels have attracted the attention of academia and industry due to their wide raw material sources, low cost and high biological safety.

[0003] However, the existing starch-based drug release hydrogel still faces many technical problems to be solved in practical application. On the one hand, the starch molecular chain is rich in a large number of hydroxyl groups, and strong hydrogen bonding easily occurs between molecules, which causes serious aggregation of starch particles in the hydrogel matrix, and cannot achieve uniform dispersion, thereby causing large fluctuations in drug loading, local drug concentration being too high or too low, which not only affects the treatment effect, but also may cause toxic side effects. At the same time, the aggregation phenomenon will destroy the continuity of the hydrogel network, further reducing the mechanical stability of the material. On the other hand, the cross-linking method of traditional starch-based hydrogel mainly depends on single physical cross-linking or weak chemical cross-linking, and the network structure formed has the defects of high porosity and uneven pore size distribution, which not only leads to insufficient mechanical strength of the hydrogel, easy swelling and rupture in physiological environment, and difficulty in maintaining long-term stable carrier form, but also makes the encapsulated drug diffuse rapidly through the large pore size, resulting in obvious burst effect, the drug release amount in the early stage of drug delivery is far beyond the therapeutic window, and the subsequent release rate drops sharply, which cannot meet the clinical needs of long-term and stable drug delivery for chronic diseases.

[0004] In addition, the existing methods for improving the dispersion of starch are mainly chemical modification, such as esterification and etherification, which can reduce the hydrogen bonding between starch molecules, but the modification process needs to use toxic chemical reagents, which not only increases the process complexity and production cost, but also leaves harmful impurities, damaging the biocompatibility of the hydrogel. While the method of increasing the amount of cross-linking agent to improve the mechanical properties will lead to excessive densification of the hydrogel network, reducing the drug loading capacity and swelling performance, which in turn restricts its application in drug release. Therefore, it is of great significance to develop a preparation technology that can selectively modify the hydroxyl groups of starch under mild conditions and simultaneously solve the problems of starch aggregation and network enhancement of hydrogel, which can promote the clinical transformation of starch-based drug release hydrogel. SUMMARY

[0005] The present application aims to overcome the deficiencies of the prior art, and provides a preparation method of a drug sustained-release modified starch hydrogel and application thereof. The present application realizes the mild modification and uniform dispersion of the hydroxyl groups of starch molecular chains through a PAA micelle-mediated starch hydroxyl modification technology and a starch gelatinization-network interweaving synergistic enhancement strategy, solves the technical problems of starch aggregation, poor mechanical properties and drug burst in traditional starch-based hydrogels, and the prepared starch-based network-enhanced sustained-release hydrogel has excellent biocompatibility, mechanical stability and drug sustained-release controllability, and can be effectively applied to oral sustained-release treatment of non-alcoholic fatty liver and other chronic liver diseases.

[0006] To achieve the above object, the present application provides the following technical scheme:

[0007] A preparation method of a drug sustained-release modified starch hydrogel, comprising the following steps:

[0008] S1: preparation of a composite solution:

[0009] 3-5g of chitosan (CTS) and 2-6g of polyethylene glycol 600 (PEG-600) are weighed and added into a mixed solvent composed of 40-60mL of a 1%-2% acetic acid aqueous solution and 20-30mL of anhydrous ethanol, the system is placed in a 30-50℃ constant temperature water bath, and stirred at a speed of 400-600r / min for 1-3h until the CTS and PEG-600 are completely dissolved to form a composite solution.

[0010] S2: preparation of a PAA micelle modified starch dispersion:

[0011] 5-7g of corn starch is weighed according to the mass fraction, added into 40-60mL of deionized water, and ultrasonically dispersed to form a starch suspension; 2-3g of polyacrylic acid (PAA, molecular weight 5000) is added into the starch suspension, and stirred until the PAA is completely dissolved; then 20-30mL of anhydrous ethanol is slowly added dropwise at a rate of 1-2mL / min, and stirred (at a speed of 300-400r / min) while adding; after stirring for 30-60min, the PAA forms micelles under the induction of ethanol and completes the modification of the starch to obtain a PAA micelle modified starch dispersion.

[0012] S3: composite crosslinking and starch gelatinization:

[0013] The PAA micelle modified starch dispersion solution in step S2 is slowly dripped into the composite solution prepared in step S1, and after the dripping is completed, stirring is carried out at a speed of 300-400 r / min for 30-40 min to ensure uniform dispersion; then 0.8-2.5 g of sodium alginate (crosslinking agent) and 0.05-0.3 g of calcium chloride (sodium alginate crosslinking accelerator) are added, and primary crosslinking is carried out at a constant temperature of 30-40℃ for 0.5-1 h; then the system is warmed to 80-85℃, and low-speed stirring is continuously carried out at 100-200 r / min for 2-3 h, so that the anhydrous ethanol is fully volatilized, and the PAA is gradually dissolved with the volatilization of the ethanol; the PAA micelle modified starch is absorbed and swelled at high temperature, and the starch molecular chain is uniformly dispersed in the sol, interweaves with the CTS-PEG network, and fills the pores to form a CTS-PEG-600-starch three-dimensional cross network structure.

[0014] S4: Post-treatment:

[0015] The hydrogel precursor of step S3 is cooled to room temperature, soaked in deionized water, and the deionized water is replaced every 4-5 h, and the replacement is carried out 4-6 times to completely remove the unreacted crosslinking agent, PAA and free drugs; the soaked hydrogel is taken out to obtain a drug release modified starch hydrogel.

[0016] The application of the drug release modified starch hydrogel in the treatment of non-alcoholic fatty liver disease, specifically includes the following operations:

[0017] S21. Drug loading:

[0018] Fucoidan is selected as a specific drug for treating non-alcoholic fatty liver disease, and a fucoidan aqueous solution with a mass concentration of 2 mg / mL is prepared; the starch-based sustained-release hydrogel prepared in step S4 is cut into small pieces with a size of 1-2 mm, and the above-mentioned aqueous solution is added according to a solid-liquid ratio of 1:20 (g / mL), and the hydrogel is soaked in the aqueous solution at 25℃ in the dark for 18 h to allow the hydrogel to fully swell and adsorb the drug; after the soaking is completed, the hydrogel is taken out, and the surface residual liquid is absorbed with sterile filter paper to obtain a fucoidan-loaded starch-based sustained-release hydrogel.

[0019] S22. Preparation and administration of oral sustained-release preparation

[0020] The drug-loaded hydrogel is placed in a freeze-drying machine and vacuum freeze-dried at -45℃ for 15 h, then crushed and sieved through a 250-mesh sieve, and the drug-loaded hydrogel particles are collected; the administration scheme is 0.5 g once a day, and after the capsule enters the stomach, the microspheres are stable in the gastric acid environment and do not release the drug; after entering the intestine, the microspheres swell by absorbing water, and the drug is slowly released relying on the dense and loose composite network of the hydrogel, and is absorbed through the intestinal tract to target the liver, thereby playing a role in regulating lipid metabolism and protecting liver cells.

[0021] Beneficial effects

[0022] (1) Adopting PAA micelle mediated starch hydroxyl modification strategy, without complex chemical modification of starch: PAA forms micelles under ethanol induction and completes modification of starch, blocking the hydrogen bonding between starch molecules and avoiding aggregation; subsequent removal of PAA by ethanol evaporation ensures uniform dispersion of starch and does not introduce residual impurities, simplifying the process and reducing costs.

[0023] (2) Synergistic enhancement of starch gelatinization and network construction: high-temperature gelatinization breaks the PAA micelle modified starch particles into molecular chains, which interweave with the CTS-PEG network, filling the original pores and constructing a dense and loose composite network structure, solving the problem of insufficient mechanical strength of traditional hydrogels and delaying drug diffusion through dense network to avoid burst release and achieve long-term sustained release.

[0024] (3) Excellent biocompatibility and environmental friendliness: all raw materials are biocompatible materials, starch and chitosan are completely biodegradable without toxic residues, and cell survival rate is ≥93%; the preparation process does not require high temperature and pressure or toxic solvents, only uses deionized water and anhydrous ethanol, which is green and environmentally friendly, suitable for large-scale production.

[0025] (4) Simple and controllable process: the parameters of each step are easy to adjust, and the PAA micelle modified starch, crosslinking and gelatinization processes are sequentially connected, which can be flexibly adjusted by adjusting the starch dosage, gelatinization temperature and other parameters to adapt to different medical scene needs. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a scanning electron microscope (SEM) photo of the hydrogel prepared in Example 1;

[0027] Figure 2 (a)-(b) are SEM pictures of the hydrogels prepared in Comparative Example 1 and Comparative Example 2, respectively;

[0028] Figure 3 is a Fourier infrared spectrum of the hydrogels in Examples 1-3 and Comparative Example 1;

[0029] Figure 4 is a photo of the hydrogel prepared in Example 1;

[0030] Figure 5 is a strain curve of Example 1, Comparative Example 1 and Comparative Example 2;

[0031] Figure 6 (a)-(c) are photos of solutions of PAA dissolved in water, then anhydrous ethanol is added, and then the anhydrous ethanol is volatilized, respectively;

[0032] Figure 7are the sustained release curves of Example 1, Comparative Example 1 and Comparative Example 2;

[0033] Figure 8 (a)-(c) are the pictures of mouse liver after application of Example 1, Comparative Example 1 and Comparative Example 2, respectively;

[0034] Figure 9 (a)-(c) are the oil red O staining pictures of mouse liver after application of Example 1, Comparative Example 1 and Comparative Example 2, respectively;

[0035] Figure 10 (a)-(c) are the hematoxylin & eosin (H&E) staining pictures of mouse liver after application of Example 1, Comparative Example 1 and Comparative Example 2, respectively;

[0036] Figure 11 are the cell survival experiment column charts of hydrogels prepared by Example 1-3 and Comparative Example 1. DETAILED DESCRIPTION

[0037] In order to make the above objectives, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below. The following content is only an example and description of the concept of the present application, and those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar ways instead, as long as they do not deviate from the concept of the present application, which shall belong to the protection scope of the present application.

[0038] The above preparation method of the present application will be described below through specific examples and comparative examples.

[0039] Example 1

[0040] A preparation method of a drug sustained-release modified starch hydrogel, comprising the following steps:

[0041] S1: Preparation of a composite solution:

[0042] 3g of CTS and 2g of PEG-600 were weighed and added into a mixed solvent composed of 40 mL of 1% acetic acid aqueous solution and 20 mL of anhydrous ethanol, and the system was placed in a 30℃ constant temperature water bath and stirred at a speed of 400r / min for 1h to form a composite solution.

[0043] S2: Preparation of a PAA micelle modified starch dispersion:

[0044] 5g corn starch was taken by mass fraction, added into 40mL deionized water, ultrasonic dispersion, forming starch suspension; 2g PAA (molecular weight 5000) was added into the starch suspension, stirring to make PAA completely dissolved; then 20mL anhydrous ethanol was slowly added, the dropwise rate was 1mL / min, stirring (speed 300r / min) while adding, after stirring for 30min, PAA micelle modified starch dispersion was obtained;

[0045] S3: composite crosslinking and starch gelatinization:

[0046] The PAA micelle modified starch dispersion in step S2 was slowly added into the composite solution prepared in step S1, after the addition was completed, stirring at 300r / min for 30min to ensure uniform dispersion; then 0.8g sodium alginate and 0.05g calcium chloride were added, and the system was crosslinked at 30℃ for 0.5h, preliminary crosslinking; then the system was heated to 80℃, and low-speed stirring was continued at 100r / min for 2h, and the three-dimensional cross network structure of "CTS-PEG-600-starch" was formed.

[0047] S4: post-treatment:

[0048] The hydrogel precursor in step S3 was cooled to room temperature, soaked in deionized water, and the deionized water was replaced every 4h, and the replacement was repeated 4 times, to obtain a drug release modified starch hydrogel.

[0049] Example 2

[0050] A method for preparing a drug release modified starch hydrogel, comprising the following steps:

[0051] S1: preparation of composite solution:

[0052] 4g CTS and 4g PEG-600 were weighed and added into 30mL mixed solvent of 1.5% acetic acid aqueous solution and 25mL anhydrous ethanol, the system was placed in a 40℃ constant temperature water bath, and stirred at 500r / min for 2h to form a composite solution.

[0053] S2: preparation of PAA micelle modified starch dispersion:

[0054] 6g corn starch was taken by mass fraction, added into 50mL deionized water, ultrasonic dispersion, forming starch suspension; 2.5g PAA (molecular weight 5000) was added into the starch suspension, stirring to make PAA completely dissolved; then 25mL anhydrous ethanol was slowly added, the dropwise rate was 1.5mL / min, stirring (speed 350r / min) while adding, after stirring for 45min, PAA micelle modified starch dispersion was obtained;

[0055] S3: composite crosslinking and starch gelatinization:

[0056] The PAA micelle modified starch dispersion solution in step S2 is slowly added into the composite solution prepared in step S1, and after the addition is completed, stirring is performed at a speed of 350 r / min for 35 min to ensure uniform dispersion; then 1.5 g of sodium alginate and 0.18 g of calcium chloride are added, and preliminary crosslinking is performed at a constant temperature of 35°C for 0.7 h; then the system is heated to 82°C, and low-speed stirring is continuously performed at 150 r / min for 2.5 h, and a "CTS-PEG-600-starch" three-dimensional cross network structure is formed.

[0057] S4: Post-processing:

[0058] The hydrogel precursor in step S3 is cooled to room temperature, soaked in deionized water, and the deionized water is replaced every 4.5 h during the soaking, and the replacement is performed 5 times to obtain a drug release modified starch hydrogel.

[0059] Example 3

[0060] A method for preparing a drug release modified starch hydrogel, comprising the following steps:

[0061] S1: Preparation of a composite solution:

[0062] 5 g of CTS and 6 g of PEG-600 are weighed and added into a mixed solvent composed of 60 mL of a 2% acetic acid aqueous solution and 30 mL of anhydrous ethanol, and the system is placed in a 50°C constant temperature water bath and stirred at a speed of 600 r / min for 3 h to form a composite solution;

[0063] S2: Preparation of a PAA micelle modified starch dispersion solution:

[0064] 7 g of corn starch is weighed according to the mass fraction, added into 60 mL of deionized water, and ultrasonically dispersed to form a starch suspension; 3 g of PAA (molecular weight 5000) is added to the starch suspension, and stirring is performed to completely dissolve the PAA; then 30 mL of anhydrous ethanol is slowly added at a rate of 2 mL / min, and stirring is performed (at a speed of 400 r / min) during the addition; after stirring for 60 min, PAA micelles are formed under the induction of ethanol and the modification of starch is completed, and a PAA micelle modified starch dispersion solution is obtained.

[0065] S3: Composite crosslinking and starch gelatinization:

[0066] The PAA micelle modified starch dispersion solution in step S2 is slowly dripped into the composite solution prepared in step S1, and after the dripping is completed, stirring is performed at a speed of 400 r / min for 40 min to ensure uniform dispersion; then 2.5 g of sodium alginate and 0.3 g of calcium chloride are added, and crosslinking is performed at a constant temperature of 40°C for 1 h to preliminarily crosslink, and then the system is warmed to 85°C, and low-speed stirring is continuously performed at 200 r / min for 3 h to form a “CTS-PEG-600-starch” three-dimensional cross network structure.

[0067] S4: Post-processing:

[0068] The hydrogel precursor of step S3 is cooled to room temperature, soaked in deionized water, and the deionized water is replaced every 5 h, and the replacement is performed 6 times to completely remove the unreacted crosslinking agent, PAA and free drug; the soaked hydrogel is taken out to obtain a drug release modified starch hydrogel.

[0069] Comparative Example 1

[0070] Preparation of a common hydrogel without PAA micelle modified starch dispersion solution

[0071] S1 Preparation of a composite solution

[0072] 3 g of CTS and 2 g of PEG-600 are weighed and added to 40 mL of a mixed solvent of 1% acetic acid aqueous solution and 20 mL of anhydrous ethanol, and stirring is performed at a constant temperature of 30°C at a speed of 400 r / min for 1 h until complete dissolution to obtain a uniform transparent composite solution.

[0073] S3 Crosslinking reaction (without starch gelatinization step)

[0074] 0.8 g of sodium alginate and 0.05 g of calcium chloride are directly added to the above-mentioned composite solution, stirring is performed at a speed of 300 r / min for 30 min, and then crosslinking is performed at a constant temperature of 30°C for 0.5 h to form a hydrogel precursor; the system is warmed to 80°C, and low-speed stirring is performed at 100 r / min for 0.8 h to fully volatilize the anhydrous ethanol to obtain a common CTS-PEG-600-sodium alginate hydrogel precursor.

[0075] S4 Post-processing

[0076] The hydrogel precursor is cooled to room temperature, soaked in deionized water, and the deionized water is replaced every 4 h, and the replacement is performed 4 times; after taking out, the water is drained to obtain a common hydrogel material without starch.

[0077] Comparative Example 2

[0078] Preparation of a common starch hydrogel without PAA micelle modified starch

[0079] The rest of the operations are exactly the same as those in Example 1, except that no PAA is added in the S2 step, and the PAA micelle modified starch cannot be achieved.

[0080] Application

[0081] Therapeutic effect of drug sustained-release modified starch hydrogel on non-alcoholic fatty liver mice

[0082] (1) Construction of non-alcoholic fatty liver mouse model

[0083] The mice were randomly divided into a normal control group and a modeling group; the normal control group was fed with ordinary feed, and the modeling group was fed with high-sugar and high-fat feed for 12 weeks. After the modeling was completed, the mice in the modeling group were randomly selected, and the liver tissue was taken for H&E staining to observe the pathological morphology of the liver tissue. If typical fatty liver characteristics such as hepatocyte steatosis and ballooning degeneration appear, the model is determined to be successfully constructed.

[0084] (2) Grouping and administration

[0085] The successfully modeled mice were randomly divided into five groups, namely Example 1 group, Example 2 group, Example 3 group, Comparative Example 1 group, and Comparative Example 2 group, and a normal control group (not modeled) and a model control group (modeled without administration) were also set.

[0086] Normal control group and model control group: 0.2 mL of normal saline per mouse per day by gavage;

[0087] Example 1-3 groups and Comparative Examples 1-2 groups: 0.2 mL of the corresponding fucoidan-loaded hydrogel microsphere suspension per mouse per day by gavage (50 mg / kg / d of fucoidan dose);

[0088] All groups were administered continuously for 8 weeks, during which the normal control group was maintained on ordinary feed, and the other groups were maintained on high-sugar and high-fat feed.

[0089] The following further demonstrates the innovative points of the present application in combination with the accompanying drawings:

[0090] The accompanying drawings of the present application directly verify the advancement of the PAA micelle modified starch technology and the starch gelatinization-network interweaving synergistic enhancement strategy from five dimensions of microstructure, chemical characterization, mechanical properties, sustained-release behavior, and biological effects, and support the core innovative points of the present application.

[0091] Figure 1 Scanning electron microscope (SEM) photograph of the hydrogel of Example 1; Figure 1 It is shown that the hydrogel prepared in Example 1 presents a uniform, dense and interconnected three-dimensional network structure without obvious starch agglomerates.

[0092] Original explanation: PAA forms micelles under the induction of ethanol and modifies starch, blocking the hydrogen bond interaction between starch molecules and avoiding starch aggregation; subsequent high-temperature gelatinization makes the starch molecular chains modified by PAA micelles fully stretch and tightly interweave with the CTS-PEG-600 network, filling the network pores and forming a uniform and dense crosslinked structure. Directly prove that the PAA micelle modified starch strategy of the application can effectively solve the problem of starch aggregation and break through the network uneven defect of traditional starch-based hydrogel caused by aggregation.

[0093] Figure 2 The SEM photos of the hydrogels of Comparative Example 1 and Comparative Example 2; Figure 2 In the hydrogel network of Comparative Example 1 (PAA micelle modified starch dispersion-free), the network structure is loose; in the hydrogel of Comparative Example 2 (PAA micelle modified starch-free), a large number of starch aggregates with a diameter of more than 20 μm can be seen, and the network around the aggregates is broken and the pore distribution is disorderly. In Comparative Example 1, the single network structure of CTS-PEG-sodium alginate is loose due to the lack of starch molecular chain filling; in Comparative Example 2, the network continuity is destroyed due to the aggregation of starch molecules through strong hydrogen bonds without PAA micelle modified starch treatment. Through comparison with Example 1, the synergistic effect of PAA micelle modified starch + starch gelatinization interweaving is highlighted, which is the key to building a uniform and dense hydrogel network.

[0094] Figure 3 The Fourier infrared spectra (FT-IR) of the hydrogels of Example 1-3 and Comparative Example 1, Figure 3 In the hydrogel network of Comparative Example 1 (PAA micelle modified starch dispersion-free), the network structure is loose; in the hydrogel of Comparative Example 2 (PAA micelle modified starch-free), a large number of starch aggregates with a diameter of more than 20 μm can be seen, and the network around the aggregates is broken and the pore distribution is disorderly. In Comparative Example 1, the single network structure of CTS-PEG-sodium alginate is loose due to the lack of starch molecular chain filling; in Comparative Example 2, the network continuity is destroyed due to the aggregation of starch molecules through strong hydrogen bonds without PAA micelle modified starch treatment. Through comparison with Example 1, the synergistic effect of PAA micelle modified starch + starch gelatinization interweaving is highlighted, which is the key to building a uniform and dense hydrogel network.

[0095] Figure 4 The actual photos of the hydrogels prepared in Example 1; Figure 4 In the hydrogel network of Comparative Example 1 (PAA micelle modified starch dispersion-free), the network structure is loose; in the hydrogel of Comparative Example 2 (PAA micelle modified starch-free), a large number of starch aggregates with a diameter of more than 20 μm can be seen, and the network around the aggregates is broken and the pore distribution is disorderly. In Comparative Example 1, the single network structure of CTS-PEG-sodium alginate is loose due to the lack of starch molecular chain filling; in Comparative Example 2, the network continuity is destroyed due to the aggregation of starch molecules through strong hydrogen bonds without PAA micelle modified starch treatment. Through comparison with Example 1, the synergistic effect of PAA micelle modified starch + starch gelatinization interweaving is highlighted, which is the key to building a uniform and dense hydrogel network.

[0096] Figure 5 The strain curves of the hydrogels of Example 1, Comparative Example 1 and Comparative Example 2; Figure 5In the present application, the breaking strain of the hydrogel of Example 1 can reach 350%, and the elastic modulus is 12 kPa; the breaking strain of Comparative Example 1 is only 120%, and the elastic modulus is 5 kPa; the breaking strain of Comparative Example 2 is about 180%, and the strain curve shows obvious stress mutation (corresponding to the fracture of starch aggregates).

[0097] The original explanation is as follows: the hydrogel of Example 1 is uniformly dispersed due to the PAA micelle modified starch, and the formed cross-linked network can uniformly bear external force, so the breaking strain is high and the elastic modulus is moderate; the loose network of Comparative Example 1 has weak anti-deformation ability; and in Comparative Example 2, the starch aggregates become stress concentration points due to the non-treatment of PAA micelle modified starch, resulting in stress mutation.

[0098] The quantitative proof shows that the mechanical stability of the hydrogel of the present application is significantly better than that of traditional hydrogels, and verifies the enhancing effect of the PAA micelle modified starch + starch gelatinization interweaving strategy on the mechanical properties.

[0099] Figure 6 (a)-(c) are photos of PAA solution in water, addition of anhydrous ethanol, and volatilization of anhydrous ethanol solution; Figure 6 (a) The PAA aqueous solution is completely transparent at the beginning; 6(b) After adding ethanol, the solution shows a Tyndall effect (visible to light path), indicating that PAA micelles are formed; 6(c) After volatilization of ethanol, the solution becomes transparent again, and the micelles are dissociated. This is because PAA is a water-soluble polymer, which is molecularly dispersed in water; ethanol as a poor solvent reduces the solubility of PAA, promotes the aggregation of PAA molecules to form micelles, and provides a structural basis for PAA micelle modified starch; after volatilization of ethanol, the proportion of water in the system rises, and PAA micelles are re-dissociated into molecular state. The principle of PAA micelle modified starch of the present application is proved, and the micelles complete the modification and dispersion of starch, and the micelles are dissociated after volatilization of ethanol without leaving impurities.

[0100] Figure 7 are the sustained-release curves of Example 1, Comparative Example 1 and Comparative Example 2; the cumulative release rate of the hydrogel of Example 1 reaches 16% within 160 min, and the release curve is a smooth curve without obvious burst release; the cumulative release rate of the hydrogel of Comparative Example 1 reaches 27% within 160 min, and the cumulative release rate of the hydrogel of Comparative Example 2 reaches 39% within 160 min. This shows that the PAA micelle modification-starch gelatinization interweaving strategy can effectively regulate the pore size distribution of the hydrogel network, solve the technical pain point of the burst release of traditional starch-based hydrogels, and realize long-acting and stable sustained release.

[0101] Figure 8(a)-(c) are the pictures of mouse liver after application of Example 1, Comparative Example 1 and Comparative Example 2, respectively; the liver morphology of the mice in the Example 1 group is close to normal, without obvious inflammatory cell infiltration; the livers of the mice in the Comparative Example 1 group and the Comparative Example 2 group show steatosis, accompanied by mild inflammatory cell infiltration. This shows that the hydrogel prepared in the application has excellent drug release targeting property, and can improve the treatment effect by stable drug delivery, reduce drug side effects, and break through the limitation of traditional preparations that the treatment effect is not good due to unstable drug delivery concentration.

[0102] Figure 9 (a)-(c) are the oil red O staining pictures after application of Example 1, Comparative Example 1 and Comparative Example 2, respectively; the red lipid droplet staining area of the liver tissue of the mice in the Example 1 group is the smallest, close to the normal control group; the lipid droplet staining area of the liver tissue of the mice in the Comparative Example 1 group and the Comparative Example 2 group is larger. This further verifies the drug delivery effectiveness of the hydrogel of the application, and in combination with the uniform network structure brought by the PAA micelle modification, realizes the precise and long-acting effect of the drug on the target, which is significantly better than the treatment effect of traditional preparations.

[0103] Figure 10 (a)-(c) are the H&E staining pictures after application of Example 1, Comparative Example 1 and Comparative Example 2, respectively; the liver tissue cells of the mice in the Example 1 group are arranged in order, without obvious pathological damage; the liver tissue of the mice in the Comparative Example 1 group and the Comparative Example 2 group shows typical fatty liver pathological features such as hepatocyte edema and ballooning degeneration. This verifies the clinical application value of the hydrogel of the application from the aspect of histopathology, realizes effective treatment of non-alcoholic fatty liver through controllable sustained-release technology, and provides technical support for clinical transformation of natural high molecular weight drug sustained-release preparations.

[0104] Figure 11 is the cell survival experiment column chart of the hydrogels prepared in Example 1-3 and Comparative Example 1. The chart shows that after the hydrogel extracts of Example 1-3 act on liver cells, the cell survival rate is all ≥93%, and the survival rate is higher than that of Comparative Example 1, which shows that the modified starch ratio can have better biocompatibility, and as the PAA micelle modified starch content increases, the cell survival rate does not decrease obviously. This proves that the physical modification strategy mediated by PAA micelles does not need to use toxic chemical reagents, solves the problem of poor biocompatibility of traditional chemical modified starch-based hydrogels due to reagent residues, and takes into account the safety and functionality of the material.

Claims

1. A method for the preparation of a pharmaceutical sustained release modified starch hydrogel, characterized by, The method comprises the following steps: S1: composite solution preparation: CTS and PEG-600 are weighed and added into a mixed solvent composed of 1%-2% acetic acid aqueous solution and anhydrous ethanol, and the system is stirred in a constant temperature water bath until CTS and PEG-600 are completely dissolved to form a composite solution; S2: PAA micelle modified starch dispersion preparation: corn starch is weighed and dispersed in deionized water to form a starch suspension; PAA is added into the starch suspension and stirred until PAA is completely dissolved; then anhydrous ethanol is slowly added dropwise while stirring to obtain a stable PAA micelle modified starch dispersion; S3: composite crosslinking and starch gelatinization: the PAA micelle modified starch dispersion obtained in step S2 is slowly added dropwise into the composite solution prepared in step S1, and stirring is performed after the dropwise addition is completed; sodium alginate and calcium chloride are added, constant temperature crosslinking is performed, then the system is heated and stirred at a low speed to obtain a hydrogel precursor; S4: post-treatment: the hydrogel precursor obtained in step S3 is cooled to room temperature, soaked in deionized water and replaced with deionized water, and then the drug release modified starch hydrogel is obtained.

2. The production method according to claim 1, characterized by, In step S1, the amount of CTS is 3-5 g, and the amount of PEG-600 is 2-6 g; the mixed solvent is composed of 40-60 mL of 1%-2% acetic acid aqueous solution and 20-30 mL of anhydrous ethanol.

3. The preparation method according to claim 1, characterized in that, In step S1, the temperature of the constant temperature water bath is 30-50℃, the stirring speed is 400-600 r / min, and the stirring time is 1-3 h.

4. The method of claim 1, wherein, In step S2, the amount of corn starch is 5-7 g, the amount of deionized water is 40-60 mL, and ultrasonic dispersion is used.

5. The preparation method according to claim 1, characterized in that, In step S2, the amount of PAA is 2-3 g, the molecular weight is 5000, the amount of anhydrous ethanol is 20-30 mL, the dropwise addition rate is 1-2 mL / min, the stirring speed is 300-400 r / min, and the stirring time is 30-60 min.

6. The method of claim 1, wherein, In step S3, the stirring speed after dropwise addition is 300-400 r / min, and the stirring time is 30-40 min.

7. The preparation method according to claim 1, characterized in that, In step S3, the amount of sodium alginate is 0.8-2.5 g, the amount of calcium chloride is 0.05-0.3 g, the constant temperature crosslinking temperature is 30-40℃, and the crosslinking time is 0.5-1 h.

8. The method of claim 1, wherein, In step S3, the temperature after heating is 80-85℃, the low-speed stirring speed is 100-200 r / min, and the stirring time is 2-3 h.

9. The method of claim 1, wherein, In step S4, the deionized water is replaced every 4-5 h, and the replacement time is 4-6 times.

10. The drug release modified starch hydrogel prepared by the preparation method of any one of claims 1-9 is used in the treatment of non-alcoholic fatty liver.

Images