An alginate-sodium poly(ethylene glycol) composite hydrogel and its preparation method

Abstract

The present invention discloses a preparation method of sodium alginate - polyethylene glycol hydrogel. By preparing sodium alginate - polyethylene glycol double - network hydrogel with sodium alginate, polyethylene glycol derivatives and their cross - linker, the mechanical properties of polyethylene glycol hydrogel are significantly improved, and it can be used clinically as a tissue filler, tissue engineering scaffold, drug carrier, sealant or embolization agent.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomedicine, and particularly relates to a sodium alginate - polyethylene glycol composite hydrogel, which can be widely used clinically as a tissue filler, tissue engineering scaffold, drug carrier, sealant or embolization agent. Background Art

[0002] Except for bones, teeth, and nails, the human body is mainly composed of soft tissues, such as muscles, cartilage, tendons, etc. These soft tissues also bear various forces, so they must have excellent mechanical properties, such as high strength, high toughness, and high elongation rate. Developing materials that can replace damaged human soft tissues is a task of great significance and challenge.

[0003] Hydrogels are polymer materials that can swell in water but are insoluble in water, forming a complex three - dimensional network structure through intermolecular interactions. Polyethylene glycol is a class of water-soluble synthetic polymers with great application value in the biomedical field. This benefits from its several unique advantages, including good biocompatibility, easy chemical modification, and good performance controllability. However, how to regulate its mechanical properties still needs to be explored. Sodium alginate is a polysaccharide natural polymer, and its molecules are composed of β - D - mannuronic acid (β - D - mannuronic, M) and α - L - guluronic acid (α - L - guluronic, G) connected by (1→4) bonds. It is a natural polysaccharide with the characteristics of non-toxic, non-irritating, good bioadhesion, biocompatibility, and biodegradability. Sodium alginate has been widely used in the food industry, cosmetics, and pharmaceutical fields.

[0004] The preparation of composite gel systems using sodium alginate has been reported. Patent CN103087334B reported a preparation method of a sodium alginate - Artemisia sphaerocephala gum composite hydrogel. By adding microporous calcium carbonate as a crosslinking agent, a hydrogel with good uniformity and high swelling rate can be obtained. Patent CN102417734A disclosed a preparation method of an oxidized sodium alginate - chitosan composite hydrogel. After blending human absorbable fibers with oxidized sodium alginate and gelatin, Ca 2+ is formed. However, the mechanical properties of hydrogels formed by crosslinking natural polymers are limited and cannot achieve ideal use effects in practical applications. Summary of the Invention

[0005] Aiming at the disadvantages of existing polyethylene glycol hydrogels in the prior art, the present invention provides a sodium alginate - polyethylene glycol composite hydrogel with good mechanical properties, which can be used clinically as a tissue filler, tissue engineering scaffold, drug carrier, sealant or embolization agent.

[0006] The specific technical solution of the present invention is as follows:

[0007] A sodium alginate - polyethylene glycol composite hydrogel is formed by in - situ cross - linking of aldehyde - terminated star - shaped multi - arm polyethylene glycol, polylysine and sodium alginate.

[0008] Preferably, the mass percentage concentration of aldehyde - terminated star - shaped multi - arm polyethylene glycol in the gel is 2 - 30%, more preferably 5 - 10%. The mass percentage concentration of polylysine is 0.2 - 10%, more preferably 0.5 - 5%. The mass percentage concentration of sodium alginate is 0.25 - 10%, more preferably 1 - 5%.

[0009] Preferably, the viscosity of sodium alginate is 2.9 - 200 cps. More preferably, it is 20 - 100 cps.

[0010] Preferably, the aldehyde group and the star - shaped multi - arm polyethylene glycol are chemically bonded by an ester bond, an ether bond, an amide bond, a urethane bond, an imine bond or a urea bond. More preferably, the aldehyde group and the star - shaped multi - arm polyethylene glycol are connected by an amide bond or an ester bond.

[0011] Preferably, the number of arms of the star - shaped multi - arm polyethylene glycol is 2 - 8, and the molecular weight of a single arm is 1000 - 5000 Da. More preferably, the number of arms is 4 - 8, and the molecular weight of a single arm is 1250 - 2500 Da.

[0012] For the composite hydrogel of the present invention, the aldehyde group is selected from one or more of aromatic aldehyde groups and alkyl aldehyde groups.

[0013] The composite hydrogel of the present invention can be further cross - linked with Ca 2+ . Ca 2+ A solution of a soluble calcium salt can be used, which can be one or more of calcium chloride, calcium bromide, calcium nitrate, calcium sulfate, calcium hydrogen phosphate, calcium acetate, and calcium hydroxide.

[0014] Preferably, the concentration of the soluble calcium salt solution is 0.5% - 30% (w / v).

[0015] Another object of the present invention is to provide the application of the composite hydrogel of the present invention in the preparation of radiotherapy pads, tissue engineering scaffolds, sealants, embolization agents, postoperative tissue sealing and anti - leakage, preventing tissue adhesion, tissue fillers, tissue repair, skin dressings or drug carrier materials.

[0016] The composite hydrogel of the present invention can be prepared by the following method:

[0017] 1. Dissolve aldehyde - terminated star - shaped multi - arm polyethylene glycol in a pH 4 - 10 buffer solution, stir to dissolve to obtain an aldehyde - terminated star - shaped multi - arm polyethylene glycol solution, and then continue to add sodium alginate and stir to obtain a mixture A;

[0018] 2. Add polylysine to physiological saline and adjust the pH to 8 - 10 to obtain polylysine solution B;

[0019] 3. Take equal volumes of solution A and solution B, mix them, pour the mixture into a mold after shaking, and remove the mold after the gel is formed (1 - 3 hours) to obtain the sodium alginate - polyethylene glycol composite hydrogel.

[0020] In the above solution A, the concentration of star - shaped multi - arm polyethylene glycol capped with benzaldehyde groups is 10 - 20%, w / v, and the concentration of sodium alginate is 2 - 10%, w / v. In solution B, the concentration of polylysine is 1 - 10%, w / v.

[0021] Preferably, the sodium alginate - polyethylene glycol composite hydrogel can also be soaked in a Ca 2+ (soluble calcium salt) solution for fixation.

[0022] Advantages of the present invention:

[0023] The sodium alginate - polyethylene glycol double - network hydrogel is prepared by using sodium alginate, polyethylene glycol derivatives and their cross - linking agents, significantly improving the mechanical properties of the polyethylene glycol hydrogel. The mechanical properties of the hydrogel can be further adjusted to meet different clinical needs by adjusting the contents of polyethylene glycol and sodium alginate, or by selecting sodium alginate with different viscosities, and by adjusting the content of the cross - linking agent. Specific embodiments

[0024] The following illustrates the specific steps of the present invention through examples, but is not limited by the examples.

[0025] The terms used in the present invention generally have the meanings commonly understood by those of ordinary skill in the art unless otherwise specified.

[0026] The present invention will be further described in detail below with reference to specific examples and data. It should be understood that the examples are only for illustrative purposes and do not limit the scope of the present invention in any way.

[0027] Example 1 Preparation of sodium alginate - polyethylene glycol composite hydrogel

[0028] Sodium alginate gel: Dissolve 0.4 g of sodium alginate with a viscosity of 20 cp in 20 mL of deionized water, stir evenly to make it viscous. After adding 4 g of CaCl2, massive precipitates appear and a complete material form cannot be formed, so mechanical property testing cannot be carried out.

[0029] Composite hydrogel 1: Dissolve 3 g of 4-arm phenylaldehyde-terminated polyethylene glycol (molecular weight 10 kDa) in 20 mL of 0.02 M phosphate buffer solution (pH 5.6) as solution A; prepare a phosphate buffer solution (pH 8.9) containing polylysine (the molar ratio of aldehyde groups of polyethylene glycol to amino groups of polylysine is 1:1.2) as solution B. Equally mix solutions A and B into a mold through a double syringe, and take it out after waiting for 2 hours to obtain composite hydrogel 1.

[0030] Composite hydrogel 2: Dissolve 3 g of 4-arm phenylaldehyde-terminated polyethylene glycol (molecular weight 10 kDa) in 20 mL of 0.02 M phosphate buffer solution (pH 5.6), add 0.4 g of sodium alginate with a viscosity of 20 cp to it, and stir evenly as solution A; prepare a phosphate buffer solution (pH 8.9) containing polylysine (the molar ratio of aldehyde groups of polyethylene glycol to amino groups of polylysine is 1:1.2) as solution B. Equally mix solutions A and B into a mold through a double syringe, and take it out after waiting for 2 hours to obtain composite hydrogel 2.

[0031] Composite hydrogel 3: Dissolve 3 g of 4-arm phenylaldehyde-terminated polyethylene glycol (molecular weight 10 kDa) in 20 mL of 0.02 M phosphate buffer solution (pH 5.6), add 0.4 g of sodium alginate with a viscosity of 20 cp to it, and stir evenly as solution A; prepare a phosphate buffer solution (pH 8.9) containing polylysine (the molar ratio of aldehyde groups of polyethylene glycol to amino groups of polylysine is 1:1.2) as solution B. Equally mix solutions A and B into a mold through a double syringe, take it out after waiting for 2 hours, soak it in 20 wt% CaCl2 solution for 1 hour and then take it out to obtain composite hydrogel 3.

[0032] Composite hydrogel 4: Dissolve 3 g of 4-arm phenylaldehyde-terminated polyethylene glycol (molecular weight 10 kDa) in 20 mL of 0.02 M phosphate buffer solution (pH 5.6), add 0.4 g of carboxymethyl cellulose with a molecular weight of 7 million Da and a substitution rate of 0.9 to it, and stir evenly as solution A; prepare a phosphate buffer solution (pH 8.9) containing polylysine (the molar ratio of aldehyde groups of polyethylene glycol to amino groups of polylysine is 1:1.2) as solution B. Equally mix solutions A and B into a mold through a double syringe, take it out after waiting for 2 hours, soak it in 20 wt% CaCl2 solution for 1 hour and then take it out to obtain composite hydrogel 4. Composite hydrogel 4 is granular and does not form a complete material morphology, so mechanical property testing cannot be carried out.

[0033] The upper and lower ends of the composite hydrogels 1-3 were fixed with the clamps of a mechanical universal testing machine respectively, and the hydrogels were stretched to break at a speed of 0.6 mm / min. The stress at break was the tensile fracture strength, and the strain at break was the tensile fracture elongation. The results are shown in Table 1.

[0034] Table 1

[0035]

[0036] Comparing hydrogels 1, 2, and 3, it can be seen that the tensile fracture elongation of the sodium alginate-polyethylene glycol composite hydrogel 3 has been significantly improved. This hydrogel can be used in applications such as tissue fillers and tissue engineering scaffolds (for example, the fracture elongation of human venous tissue is 89%, and the fracture elongation of the human bladder is 226%). The single sodium alginate hydrogel is viscous, and due to the lack of a continuous double-network structure, its mechanical properties are poor. In composite hydrogel 4, sodium alginate was replaced by carboxymethyl cellulose, which is also a common polysaccharide natural polymer, but a continuous double-network was not actually formed, indicating that the structure of polysaccharide natural polymers has an important impact on the formation of hydrogels.

[0037] Effect of the preparation method of the solution on the composite hydrogel in Example 2

[0038] Based on the composition and preparation method of composite hydrogel 3 in Example 1, the effects of the preparation method and addition order on the hydrogel were investigated.

[0039] Method 1: 3 g of 4-armed phenylaldehyde-terminated polyethylene glycol (molecular weight 10 kDa) and 0.4 g of sodium alginate with a viscosity of 20 cp were simultaneously dissolved in 20 mL of a 0.02 M phosphate buffer solution (pH 5.6). After stirring, the solution was turbid and difficult to flow, and it was impossible to continue preparing the hydrogel.

[0040] Method 2: 3 g of 4-armed phenylaldehyde-terminated polyethylene glycol (molecular weight 10 kDa) was dissolved in 20 mL of a 0.02 M phosphate buffer solution (pH 5.6). CaCl2 was added to it to form a 20 wt% CaCl2 solution. After stirring, a precipitate was formed, and it was impossible to continue preparing the hydrogel.

[0041] Method 3: Dissolve 3 g of 4-arm phenylaldehyde-terminated polyethylene glycol (molecular weight 10 kDa) in 20 mL of 0.02 M phosphate buffer solution (pH 5.6). Add 0.4 g of sodium alginate with a viscosity of 20 cp to it and stir evenly to obtain Solution A. Prepare a phosphate buffer solution (pH 8.9) containing polylysine (the molar ratio of the phenylaldehyde group of polyethylene glycol to the amino group of polylysine is 1:1.2), and add CaCl2 to form a 20 wt% CaCl2 solution as Solution B. Mix Solutions A and B in equal amounts into a mold through a double syringe, but it cannot be cured to form a hydrogel.

[0042] The above research shows that the preparation method and addition order of each component solution have an important impact on the formation of the hydrogel.

[0043] Example 3 Regulation of the mechanical properties of the composite hydrogel by the viscosity of sodium alginate

[0044] Dissolve 3 g of 4-arm phenylaldehyde-terminated polyethylene glycol (molecular weight 10 kDa) in 20 mL of 0.02 M phosphate buffer solution (pH 5.6). Add 0.4 g of sodium alginate with viscosities of 2.9 cp and 200 cp to it respectively and stir evenly to obtain Solution A. Prepare a phosphate buffer solution (pH 8.9) containing polylysine (the molar ratio of the aldehyde group of polyethylene glycol to the amino group of polylysine is 1:1.2) as Solution B. Mix Solutions A and B in equal amounts into a mold through a double syringe, take it out after waiting for 2 hours, soak it in a 20 wt% CaCl2 solution for 1 hour and then take it out to obtain composite hydrogels 5 and 6. Detect the tensile fracture strength and tensile fracture elongation of composite hydrogels 5 and 6, and the results are shown in Table 2.

[0045] Table 2

[0046] Sodium alginate viscosity Tensile fracture strength Tensile fracture elongation Composite hydrogel 3 20 cp 2.36 kPa 248.9％ Composite hydrogel 5 2.9 cp 5.77 kPa 154.2％ Composite hydrogel 6 200 cp 2.07 kPa 170.5％

[0047] Comparing hydrogels 3, 5, and 6, it can be seen that sodium alginate with a viscosity between 2.9 - 200 cp can be used to regulate the mechanical properties of the sodium alginate-polyethylene glycol composite hydrogel to meet different applications such as tissue fillers, tissue engineering scaffolds, drug carriers, sealants or embolization agents.

[0048] Example 4 Regulation of the mechanical properties of the composite hydrogel by the concentration of sodium alginate

[0049] Dissolve 3 g of 4-arm phenylaldehyde-terminated polyethylene glycol (molecular weight 10 kDa) in 20 mL of 0.02 M phosphate buffer solution (pH 5.6). Add 0.1 g, 0.2 g, and 1 g of sodium alginate with a viscosity of 20 cp to it respectively, and stir evenly to obtain Solution A; prepare a phosphate buffer solution (pH 8.9) containing polylysine (the molar ratio of the aldehyde group of polyethylene glycol to the amino group of polylysine is 1:1.2) as Solution B. Mix Solutions A and B equally into a mold through a double syringe, take it out after waiting for 2 hours, soak it in 20 wt% CaCl2 solution for 1 hour and then take it out to obtain composite hydrogels 7, 8, and 9. Detect the tensile fracture strength and tensile fracture elongation of composite hydrogels 7 - 9, and the results are shown in Table 3.

[0050] Table 3

[0051] Sodium alginate concentration (w / v, %) Tensile fracture strength Tensile fracture elongation Composite hydrogel 3 2％ 2.36 kPa 248.9％ Composite hydrogel 7 0.5％ 4.12 kPa 80.2％ Composite hydrogel 8 1％ 12.32 kPa 139.4％ Composite hydrogel 9 5％ 0.81 kPa 224.5％

[0052] Comparing hydrogels 3, 7, 8, and 9, it can be seen that the mechanical properties of sodium alginate - polyethylene glycol composite hydrogels can be adjusted by using the concentration of sodium alginate to meet different applications such as tissue fillers, tissue engineering scaffolds, drug carriers, sealants, or embolization agents.

[0053] Example 5 Regulation of the Mechanical Properties of Composite Hydrogels by the Concentration of Calcium Chloride

[0054] Dissolve 3 g of 4-arm phenylaldehyde-terminated polyethylene glycol (molecular weight 10 kDa) in 20 mL of 0.02 M phosphate buffer solution (pH 5.6). Add 0.4 g of sodium alginate with a viscosity of 20 cp to it, and stir evenly to obtain Solution A; prepare a phosphate buffer solution (pH 8.9) containing polylysine (the molar ratio of the aldehyde group of polyethylene glycol to the amino group of polylysine is 1:1.2) as Solution B. Mix Solutions A and B equally into a mold through a double syringe, take it out after waiting for 2 hours, soak it in 5, 10, and 30 wt% CaCl2 solutions for 1 hour and then take it out to obtain composite hydrogels 10 - 12. Detect the tensile fracture strength and tensile fracture elongation of composite hydrogels 10 - 12, and the results are shown in Table 4.

[0055] Table 4

[0056] <![CDATA[CaCl2 concentration (w / v, %)]]> Tensile fracture strength Tensile fracture elongation Composite hydrogel 3 20％ 2.36 kPa 248.9％ Composite hydrogel 10 0.5％ 5.26 kPa 68.2％ Composite hydrogel 11 10％ 2.56 kPa 140.5％ Composite hydrogel 12 30％ 2.0 kPa 239％

[0057] Comparing hydrogels 3, 10, 11, and 12, it can be seen that the mechanical properties of sodium alginate - polyethylene glycol composite hydrogels can be adjusted by using the concentration of calcium chloride to meet different applications such as tissue fillers, tissue engineering scaffolds, drug carriers, sealants, or embolization agents.

Claims

1. A sodium alginate-polyethylene glycol composite hydrogel, characterized in that The composite hydrogel is formed by in-situ cross-linking of aldehyde-terminated star-shaped multi-arm polyethylene glycol, polylysine, and sodium alginate. The mass percentage concentration of the aldehyde-terminated star-shaped multi-arm polyethylene glycol in the gel is 5-15%, the mass percentage concentration of polylysine is 0.2-3%, and the mass percentage concentration of sodium alginate is 0.25-10%. The composite hydrogel is prepared by the following method: dissolving the aldehyde-terminated star-shaped multi-arm polyethylene glycol in a pH 4-10 buffer solution, stirring to dissolve the aldehyde-terminated star-shaped multi-arm polyethylene glycol solution, and then adding sodium alginate and stirring to obtain a mixed solution A; adding polylysine to physiological saline and adjusting the pH to 8-10 to obtain a polylysine solution B; taking equal volumes of solution A and solution B, mixing, shaking, and pouring into a mold; after the gel is formed, removing the mold to obtain a sodium alginate-polyethylene glycol composite hydrogel.

2. The composite hydrogel according to claim 1, characterized in that The viscosity of the sodium alginate is 2.9-200 cps.

3. The composite hydrogel according to claim 1, characterized in that The aldehyde group and the star-shaped multi-arm polyethylene glycol are connected by an ester bond, an ether bond, an amide bond, a urethane bond, an imine bond or a urea bond.

4. The composite hydrogel according to claim 3, characterized in that The aldehyde group and the star-shaped multi-arm polyethylene glycol are connected via an amide bond or an ester bond.

5. The composite hydrogel according to claim 1, characterized in that The number of arms of the star-shaped multi-arm polyethylene glycol is 2-8, the molecular weight of a single arm is 1000-5000 Da, and the aldehyde group is selected from one or more of aromatic aldehyde groups and alkyl aldehyde groups.

6. The composite hydrogel according to any one of claims 1 to 5, characterized in that The composite hydrogel is further treated with Ca 2+ Cross-linking.

7. Use of the composite hydrogel according to any one of claims 1 to 6 in the preparation of radiotherapy gaskets, tissue engineering scaffolds, sealants, embolic agents, postoperative tissue sealing and anti-leakage, anti-tissue adhesion, tissue fillers, tissue repair, skin dressings or drug carrier materials.

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