CN117777489A - Natural polysaccharide hydrogel for bone repair and preparation method and application method thereof - Google Patents

Abstract

The invention provides a natural polysaccharide hydrogel for bone repair, a preparation method and a use method thereof. The natural polysaccharide is modified to prepare aldehyde modified xyloglucan and double bond modified chitosan, and the Schiff base reaction between aldehyde and amino groups of the chitosan is utilized to construct hydrogel based on a dynamic covalent cross-linked network, so that the hydrogel can be directly injected into irregular bone defect positions for filling. Under the photoinitiation condition, double bonds in the hydrogel undergo addition reaction to form a second cross-linked network structure based on covalent bonds, so that the elastic modulus of the material is improved. The active substances strontium ions and phosphate are loaded in the hydrogel, the microelement strontium ions play an important role in maintaining the health of natural bones, and can promote the proliferation and differentiation of osteoblasts and the formation of blood vessels, and the phosphate is the main component of bone tissues, so that the phosphate is matched with the strontium ions to jointly promote the bone repair.

Description

Natural polysaccharide hydrogel for bone repair and preparation method and use method thereof

Technical Field

The invention belongs to the field of biomedical polymer materials, and particularly relates to a natural polysaccharide hydrogel for bone repair and a preparation method and a use method thereof.

Background technique

Bones are an important supporting structure of the human body. For mild and small-scale bone injuries, bone tissue can restore health through self-repair ability. However, in more cases due to trauma, infection, tumor, osteomyelitis, surgical debridement and some congenital diseases, etc. Bone trauma caused by the disease cannot repair itself, resulting in an increasing incidence of bone injuries, which brings huge economic pressure and psychological burden to patients.

With the development of tissue engineering technology, bone tissue engineering has played an important role in bone defect repair. It can promote bone tissue growth, repair bone defects, and present bioactive substances. Hydrogel, as a water-containing three-dimensional network polymer, is composed of natural or synthetic polymers and has good toughness. In particular, natural polysaccharide hydrogels exhibit high water retention capacity, good biocompatibility, biodegradability and non-toxicity, and are excellent materials for bone repair. Therefore, natural polysaccharide hydrogels can simulate the natural tissue environment, provide structural support for the defect site, and promote the repair of bone defect sites. In particular, injectable hydrogels can adapt to the different shapes of bone defect sites and solidify in situ by photocrosslinking, which has unique advantages.

Xyloglucan (XG) extracted from tamarind seeds is a hemicellulose and the main component of higher plant cell walls. It is a natural branched polysaccharide with a main chain composed of glucose rings and side chains. It has a xylose sugar ring and a galactose ring with biologically active functions. Chitosan (CS) is a cationic polysaccharide containing a large number of amino groups with biodegradability, biocompatibility, antibacterial activity and hemostatic ability, and has been widely used in tissue engineering, drug delivery and injectable hydrogels .

The trace element strontium ions play an important role in maintaining natural bone health and can promote osteoblast proliferation and differentiation as well as blood vessel formation. Its physiological functions are also closely related to bone formation. Phosphate is the main component of bone tissue. Phosphate and strontium ions are combined to promote bone repair.

Contents of the invention

This application provides a natural polysaccharide hydrogel for bone repair, which can meet the needs of bone defects of different shapes. The loaded strontium ions and phosphate can promote the proliferation and differentiation of osteoblasts and the formation of blood vessels. Two natural polysaccharides, xyloglucan and chitosan, were selected as raw materials, and were subjected to aldehyde modification and methacrylamide modification respectively. The Schiff base reaction between the aldehyde group and the amino group is used to construct a dynamic covalent network, and then the covalent network is constructed in situ through photoinitiated double bond polymerization to prepare an injectable hydrogel with flexible control of rheological and mechanical properties. The good injectable performance also provides application prospects for 3D bioprinting.

According to the first aspect of the present application, a preparation method of natural polysaccharide hydrogel for bone repair is provided, including:

(1) Mix solution A containing aldehylated natural polysaccharides and solution B containing double bond modified chitosan derivatives. The aldehyde groups in the aldehylated natural polysaccharides are mixed with the double bond modified chitosan derivatives. The amino groups in the polysaccharide hydrogel react through Schiff base reaction I to obtain a dynamic covalent network of the polysaccharide hydrogel;

(2) Addition reaction occurs to the dynamic covalent network of the polysaccharide hydrogel obtained in step (1) under ultraviolet irradiation to obtain a natural polysaccharide hydrogel containing a double cross-linked network for bone repair;

The solution A includes any one of a bone repair promoter and a mixture E;

The solution B includes a bone repair accelerator and another one of the mixture E;

The mixture E includes strontium ions and photoinitiator.

Specifically, in step (1), strontium ions combine with phosphate ions in the bone repair agent to form strontium phosphate.

Optionally, the bone repairing agent is selected from at least one of polyphosphate and phosphate.

Optionally, the aldehylated natural polysaccharide is selected from at least one of aldehyde-modified xylglucose and aldehyde-modified hyaluronic acid;

The strontium ions are selected from strontium chloride hexahydrate;

The double bond modified chitosan derivative is methacrylated chitosan.

Optionally, in the added raw materials (double-bond-modified chitosan derivative, aldehyde-modified xyloglucan, strontium chloride hexahydrate, sodium polyphosphate, initiator), the mass content of the initiator is 0.1-1.0%.

Optionally, the polyphosphate is selected from sodium polyphosphate; the phosphate is selected from sodium phosphate.

Optionally, the mass ratio of the double bond modified chitosan derivative, the aldehylated natural polysaccharide, the strontium ion and the bone promoter is 0.5-2:1-2:0.1-1.5: 0.1-2.

Optionally, the photoinitiator is selected from phenyl-2,4,6-trimethylbenzoyl lithium phosphate, 2-hydroxy-2-methyl-1-phenyl acetone, 2-hydroxy-2 -Methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone, 2,2'-azo(2-methyl-N-(2-hydroxyethyl)propionamide) at least one of them.

As an embodiment of the present application, the preparation method comprises:

Step 1) subjecting xyloglucan to oxidation reaction to obtain aldehyde-modified xyloglucan; dissolving the aldehyde-modified xyloglucan in water to obtain an aldehyde-modified xyloglucan aqueous solution; and adding sodium polyphosphate and stirring to obtain a uniform solution;

Step 2) React chitosan with methacrylic anhydride to obtain a double bond modified chitosan derivative; dissolve the double bond modified chitosan derivative in water to obtain a double bond modified chitosan derivative aqueous solution ;Add strontium chloride hexahydrate and photoinitiator, stir to obtain a uniform solution;

Step 3) Mix the aldehyde-modified xyloglucan aqueous solution in step 1) and the double-bond modified chitosan derivative aqueous solution in step 2) to generate a dynamic covalent network through Schiff base reaction to obtain an injectable Natural polysaccharide hydrogels for bone repair.

Optionally, the mass ratio of the double-bond modified chitosan derivative to the aldehylated natural polysaccharide is 1:0.5-2.0.

Optionally, the preparation method of the aldehylated natural polysaccharide includes:

The aqueous solution containing natural polysaccharides and oxidizing agent is reacted to obtain aldehylated natural polysaccharides.

Preferably, the oxidizing agent is selected from sodium periodate.

Optionally, in the aqueous solution containing natural polysaccharides and oxidizing agents, the concentration of natural polysaccharides is 0.5-2.0wt%; the concentration of oxidizing agents is 0.1-3wt%.

Optionally, the reaction conditions are: react in the dark for 2 to 12 hours.

Optionally, the preparation method of the aldehylated natural polysaccharide includes:

Xyloglucan and sodium periodate react in aqueous solution in the dark for 2 to 12 hours, and then add ethylene glycol to terminate the reaction.

As an embodiment of the present application, the preparation method of the double bond modified chitosan derivative includes:

The aqueous solution containing chitosan derivative, glacial acetic acid and methacrylic anhydride is reacted at 60-70° C. for 2-6 hours, and then the pH is adjusted to 6.0-7.0.

Optionally, the preparation method of the aqueous solution containing chitosan, glacial acetic acid, and methacrylic anhydride is: adding 2 to 6 parts by volume of ice to 200 to 400 parts by volume of an aqueous solution of 0.5 to 2.0 wt% chitosan. Mix acetic acid and 1 to 4 parts by volume of methacrylic anhydride evenly.

In this application, the natural polysaccharide hydrogel containing a double cross-linked network for bone repair is solid and has no fluidity. For convenience of use, step (2) can be carried out under light-proof conditions to obtain no A hydrogel that undergoes double bond polymerization. This hydrogel without double bond polymerization is fluid and can adapt to the shape of the defect, which is beneficial to filling irregularly shaped bone defects. Then it is irradiated with external light to increase its modulus and stop flowing.

According to the second aspect of the present application, a natural polysaccharide hydrogel for bone repair is provided. The natural polysaccharide hydrogel for bone repair is selected from the natural polysaccharide hydrogel for bone repair prepared according to the above method. Any of the sugar hydrogels.

According to the third aspect of the present application, a method for using the above-mentioned natural polysaccharide hydrogel for bone repair is provided, and the step (2) of preparing the above-mentioned natural polysaccharide hydrogel for bone repair is performed under light-proof conditions. Proceed as follows to obtain material G without addition reaction;

Inject the material G without addition reaction into the bone defect location, and then irradiate it with ultraviolet light to promote wound healing; or,

The material G is used as a biological 3D printing raw material, and the material G is irradiated with ultraviolet light for 3D printing and manufacturing, and is placed at the bone defect location.

Compared with the prior art, the present invention has the following beneficial effects:

The invention relates to a biologically active natural polysaccharide hydrogel for bone repair, which is based on natural polysaccharides and is rich in content and easy to obtain. Aldehyde-modified xyloglucan was prepared by modifying natural polysaccharides. The Schiff base reaction between the aldehyde group and the amino group of chitosan is used to construct a cross-linked network based on dynamic covalent bonds. It has good injectability and self-healing properties and can match the needs of different bone defects. In-situ light After curing, it provides structural support to the defective area and promotes the repair of the bone defective area. The trace element strontium ions play an important role in maintaining natural bone health and can promote osteoblast proliferation and differentiation as well as blood vessel formation. Its physiological functions are also closely related to bone formation. Phosphate is the main component of bones. Phosphate and strontium ions are combined to promote bone repair.

Description of the drawings

Figure 1 is a schematic structural diagram of methacrylated chitosan;

FIG2 is a schematic diagram of the structure of oxidized xyloglucan;

Figure 3 is an EDS energy spectrum test chart of the hydrogel prepared in Example 1. (a) is the microstructure of the hydrogel; (b) is the distribution of element C; (c) is the distribution of element O; (d) is the distribution of element N; (e) is the distribution of element Sr; ( f) is the distribution of element P.

Detailed ways

The present application will be described in detail below with reference to examples, but the present application is not limited to these examples.

Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

Figure 1 is a schematic structural diagram of methacrylated chitosan in this application; Figure 2 is a schematic structural diagram of oxidized xyloglucan.

The initiators used in the examples are phenyl-2,4,6-trimethylbenzoyl lithium phosphate.

Example 1

Step 1: Preparation of tamarind xyloglucan

(1) Weigh 10g of tamarind powder and dissolve it in 1000mL of deionized water, stir at 40°C for 24h until a viscous solution is formed;

(2) Centrifuge the above viscous solution and take the supernatant to remove insoluble impurities and proteins;

(3) Slowly adding the supernatant into excess ethanol to obtain xyloglucan precipitate, and drying after three precipitation processes to obtain the purified xyloglucan raw material.

Step 2: Preparation of aldehylated xyloglucan

(1) Weigh 3.0g xyloglucan and dissolve it in 300mL deionized water to obtain a 1.0wt% xyloglucan solution;

(2) Weigh 0.3g of sodium periodate, add it to the above solution, and stir for 2 hours in the dark to perform the oxidation reaction;

(3) Add 0.5 mL of ethylene glycol to the above solution, react for 6 hours, and remove unreacted sodium periodate;

(4) Put the above reacted solution into an 8000D dialysis bag and dialyze it for 3 to 5 days to remove impurities, and freeze-dry to obtain aldehyde-modified xyloglucan.

Step 3: Preparation of methacrylylated chitosan

(1) Weigh 3g of chitosan (deacetylation degree 95%) and place it in 300mL of deionized water, add 4mL of acetic acid dropwise to help dissolve, stir until the chitosan is completely dissolved, and raise the temperature to 60°C;

(2) Add 2 mL of methacrylic anhydride dropwise to the above solution, and react at 60°C for 3 hours;

(3) Add 10wt% sodium bicarbonate aqueous solution dropwise to neutralize excess acid, adjust the pH to 6.5, and stir overnight to reduce the generation of bubbles;

(4) Put the above reacted solution into an 8000D dialysis bag and dialyze for 4 days, then freeze-dry to obtain methacrylated chitosan.

Step 4: Preparation of polysaccharide hydrogel

(1) Dissolve 0.2g of aldehyde-modified xyloglucan in 10 mL of deionized water, stir to form a uniform solution with a mass fraction of 6.0 wt%, and obtain an aqueous solution of aldehyde-modified xyloglucan; on this basis, add 0.1g sodium polyphosphate, stir to obtain a uniform solution.

(2) Dissolve 0.3g methacryloyl chitosan derivative in 10mL deionized water, stir to form a uniform solution with a mass fraction of 1.5wt%, and obtain a double bond modified chitosan derivative aqueous solution; on this basis On top, add 0.1g strontium chloride hexahydrate and 5mg photoinitiator, and stir to obtain a uniform solution.

(3) Mix the two obtained solutions at a volume ratio of 1:1. The amino groups on chitosan and the aldehyde groups on xyloglucan react quickly to form Schiff base bonds, obtaining dynamic interactions based on non-covalent interactions. Covalently bonded injectable hydrogels. After the gel is injected into the target position, the double bond polymerization on chitosan is initiated in situ under 405nm blue light irradiation to form a covalent network, thereby constructing a bioactive injectable product based on the double network with easily adjustable modulus. Natural polysaccharide hydrogel for bone repair.

Figure 3 is an EDS spectrum test diagram of the hydrogel prepared in this embodiment. (a) is the microstructure diagram of the hydrogel; (b) is the distribution of element C; (c) is the distribution of element O; (d) is the distribution of element N; (e) is the distribution of element Sr; (f) is the distribution of element P.

Example 2

Step 1: Preparation of tamarind xyloglucan

(1) Weigh 10g of tamarind powder and dissolve it in 1000mL of deionized water, stir at 40°C for 24h until a viscous solution is formed;

(2) Centrifuge the above viscous solution and take the supernatant to remove insoluble impurities and proteins;

(3) Slowly add the supernatant to excess ethanol to obtain xyloglucan precipitation. After three precipitation processes, the purified xyloglucan raw material can be obtained by drying.

Step 2: Preparation of aldehylated xyloglucan

(1) Weigh 3.0g xyloglucan and dissolve it in 300mL deionized water to obtain a 1.0wt% xyloglucan solution;

(2) Weigh 0.3g of sodium periodate, add it to the above solution, and stir for 2 hours in the dark to perform the oxidation reaction;

(3) Add 0.5 mL of ethylene glycol to the above solution, react for 6 hours, and remove unreacted sodium periodate;

(4) Put the above reacted solution into an 8000D dialysis bag and dialyze it for 3 to 5 days to remove impurities, and freeze-dry to obtain aldehyde-modified xyloglucan.

Step 3: Preparation of methacryloyl chitosan

(1) Weigh 3g of chitosan (deacetylation degree 95%) and place it in 300mL of deionized water, add 4mL of acetic acid dropwise to help dissolve, stir until the chitosan is completely dissolved, and raise the temperature to 60°C;

(2) 2 mL of methacrylic anhydride was added dropwise to the above solution and reacted at 60° C. for 3 h;

(3) adding 10 wt % sodium bicarbonate aqueous solution dropwise to neutralize the excess acid, adjusting the pH to 6.5, and stirring overnight to reduce bubble generation;

(4) The above-reacted solution was placed in a 8000D dialysis bag and dialyzed for 4 days, and then freeze-dried to obtain methacryloyl chitosan.

Step 4: Preparation of polysaccharide hydrogel

(1) 0.3 g of aldehyde-modified xyloglucan was dissolved in 10 mL of deionized water, and stirred to form a uniform solution with a mass fraction of 6.0 wt %, thereby obtaining an aldehyde-modified xyloglucan aqueous solution; on this basis, 0.2 g of sodium polyphosphate was added, and stirred to obtain a uniform solution.

(2) Dissolve 0.2g methacryloyl chitosan derivative in 10mL deionized water, stir to form a uniform solution with a mass fraction of 1.5wt%, and obtain a double bond modified chitosan derivative aqueous solution; on this basis On top, add 0.2g strontium chloride hexahydrate and 5mg photoinitiator, and stir to obtain a uniform solution.

(3) The two solutions were mixed in a volume ratio of 1:1, and the amino groups on chitosan reacted rapidly with the aldehyde groups on xyloglucan to form Schiff base bonds, thereby obtaining a dynamic covalent bond injectable hydrogel based on non-covalent interactions. After the gel was injected into the target location, the double bonds on the chitosan were polymerized in situ under 405 nm blue light irradiation to form a covalent network, thereby constructing a bioactive injectable natural polysaccharide hydrogel for bone repair with a double network and easily adjustable modulus.

Example 3

Step 1: Preparation of tamarind xyloglucan

(1) Weigh 10g of tamarind powder and dissolve it in 1000mL of deionized water, stir at 40°C for 24h until a viscous solution is formed;

(2) Centrifuge the above viscous solution and take the supernatant to remove insoluble impurities and proteins;

(3) Slowly adding the supernatant into excess ethanol to obtain xyloglucan precipitate, and drying after three precipitation processes to obtain the purified xyloglucan raw material.

Step 2: Preparation of aldehylated xyloglucan

(1) Weigh 3.0g xyloglucan and dissolve it in 300mL deionized water to obtain a 1.0wt% xyloglucan solution;

(2) Weigh 0.3g of sodium periodate, add it to the above solution, and stir for 2 hours in the dark to perform the oxidation reaction;

(3) Add 0.5 mL of ethylene glycol to the above solution, react for 6 hours, and remove unreacted sodium periodate;

(4) Put the above reacted solution into an 8000D dialysis bag and dialyze for 3 to 5 days to remove impurities, and then freeze-dry to obtain aldehyde-modified xyloglucan.

Step 3: Preparation of methacrylylated chitosan

(1) Weigh 3g of chitosan (deacetylation degree 95%) and place it in 300mL of deionized water, add 4mL of acetic acid dropwise to help dissolve, stir until the chitosan is completely dissolved, and raise the temperature to 60°C;

(2) 2 mL of methacrylic anhydride was added dropwise to the above solution and reacted at 60° C. for 3 h;

(3) Add 10wt% sodium bicarbonate aqueous solution dropwise to neutralize excess acid, adjust the pH to 6.5, and stir overnight to reduce the generation of bubbles;

(4) Put the above reacted solution into an 8000D dialysis bag and dialyze for 4 days, then freeze-dry to obtain methacrylated chitosan.

Step 4: Preparation of polysaccharide hydrogel

(1) Dissolve 0.3g of aldehyde-modified xyloglucan in 10 mL of deionized water, stir to form a uniform solution with a mass fraction of 6.0wt%, and obtain an aqueous solution of aldehyde-modified xyloglucan; on this basis, add 0.2g sodium polyphosphate, stir to obtain a uniform solution.

(2) Dissolve 0.3g methacryloyl chitosan derivative in 10mL deionized water, stir to form a uniform solution with a mass fraction of 1.5wt%, and obtain a double bond modified chitosan derivative aqueous solution; on this basis On top, add 0.1g strontium chloride hexahydrate and 5mg photoinitiator, and stir to obtain a uniform solution.

(3) Mix the two obtained solutions at a volume ratio of 1:1. The amino groups on chitosan and the aldehyde groups on xyloglucan react quickly to form Schiff base bonds, obtaining dynamic interactions based on non-covalent interactions. Covalently bonded injectable hydrogels. After the gel is injected into the target position, the double bond polymerization on chitosan is initiated in situ under 405nm blue light irradiation to form a covalent network, thereby constructing a bioactive injectable product based on the double network with easily adjustable modulus. Natural polysaccharide hydrogel for bone repair.

Example 4

Step 1: Preparation of tamarind xyloglucan

(1) Weigh 10g of tamarind powder and dissolve it in 1000mL of deionized water, stir at 40°C for 24h until a viscous solution is formed;

(2) Centrifuge the above viscous solution and take the supernatant to remove insoluble impurities and proteins;

(3) Slowly add the supernatant to excess ethanol to obtain xyloglucan precipitation. After three precipitation processes, the purified xyloglucan raw material can be obtained by drying.

Step 2: Preparation of aldehyde-modified xyloglucan

(1) Weigh 3.0g xyloglucan and dissolve it in 300mL deionized water to obtain a 1.0wt% xyloglucan solution;

(2) Weigh 0.45g of sodium periodate, add it to the above solution, and stir for 2 hours in the dark to perform the oxidation reaction;

(3) Add 0.5 mL of ethylene glycol to the above solution and react for 6 h to remove unreacted sodium periodate;

(4) Put the above reacted solution into an 8000D dialysis bag and dialyze it for 3 to 5 days to remove impurities, and freeze-dry to obtain aldehyde-modified xyloglucan.

Step 3: Preparation of methacryloyl chitosan

(1) Weigh 3g of chitosan (deacetylation degree 95%) and place it in 300mL of deionized water, add 4mL of acetic acid dropwise to help dissolve, stir until the chitosan is completely dissolved, and raise the temperature to 60°C;

(2) Add 2 mL of methacrylic anhydride dropwise to the above solution, and react at 60°C for 3 hours;

(3) Add 10wt% sodium bicarbonate aqueous solution dropwise to neutralize excess acid, adjust the pH to 6.5, and stir overnight to reduce the generation of bubbles;

(4) Put the above reacted solution into an 8000D dialysis bag and dialyze for 4 days, then freeze-dry to obtain methacrylated chitosan.

Step 4: Preparation of polysaccharide hydrogel

(1) Dissolve 0.2g of aldehyde-modified xyloglucan in 10 mL of deionized water, stir to form a uniform solution with a mass fraction of 6.0 wt%, and obtain an aqueous solution of aldehyde-modified xyloglucan; on this basis, add 0.25g sodium polyphosphate, stir to obtain a uniform solution.

(2) Dissolve 0.3g methacryloyl chitosan derivative in 10mL deionized water, stir to form a uniform solution with a mass fraction of 1.5wt%, and obtain a double bond modified chitosan derivative aqueous solution; on this basis On top, add 0.15g strontium chloride hexahydrate and 5mg photoinitiator, and stir to obtain a uniform solution.

(3) The two solutions were mixed in a volume ratio of 1:1, and the amino groups on chitosan reacted rapidly with the aldehyde groups on xyloglucan to form Schiff base bonds, thereby obtaining a dynamic covalent bond injectable hydrogel based on non-covalent interactions. After the gel was injected into the target location, the double bonds on the chitosan were polymerized in situ under 405 nm blue light irradiation to form a covalent network, thereby constructing a bioactive injectable natural polysaccharide hydrogel for bone repair with a double network and easily adjustable modulus.

Example 5

Step 1: Preparation of tamarind xyloglucan

(1) Weigh 10g of tamarind powder and dissolve it in 1000mL of deionized water, stir at 40°C for 24h until a viscous solution is formed;

(2) Centrifuge the above viscous solution and take the supernatant to remove insoluble impurities and proteins;

(3) Slowly add the supernatant to excess ethanol to obtain xyloglucan precipitation. After three precipitation processes, the purified xyloglucan raw material can be obtained by drying.

Step 2: Preparation of aldehylated xyloglucan

(1) Weigh 3.0g xyloglucan and dissolve it in 300mL deionized water to obtain a 1.0wt% xyloglucan solution;

(2) Weigh 0.45g of sodium periodate, add it to the above solution, and stir for 2 hours in the dark to perform the oxidation reaction;

(3) Add 0.5 mL of ethylene glycol to the above solution, react for 6 hours, and remove unreacted sodium periodate;

(4) Put the above reacted solution into an 8000D dialysis bag and dialyze it for 3 to 5 days to remove impurities, and freeze-dry to obtain aldehyde-modified xyloglucan.

Step 3: Preparation of methacrylylated chitosan

(1) Weigh 3g of chitosan (deacetylation degree 95%) and place it in 300mL of deionized water, add 4mL of acetic acid dropwise to help dissolve, stir until the chitosan is completely dissolved, and raise the temperature to 60°C;

(2) 4 mL of methacrylic anhydride was added dropwise to the above solution and reacted at 60° C. for 3 h;

(3) Add 10wt% sodium bicarbonate aqueous solution dropwise to neutralize excess acid, adjust the pH to 6.5, and stir overnight to reduce the generation of bubbles;

(4) The above-reacted solution was placed in a 8000D dialysis bag and dialyzed for 4 days, and then freeze-dried to obtain methacryloyl chitosan.

Step 4: Preparation of polysaccharide hydrogel

(1) Dissolve 0.2g of aldehyde-modified xyloglucan in 10 mL of deionized water, stir to form a uniform solution with a mass fraction of 6.0 wt%, and obtain an aqueous solution of aldehyde-modified xyloglucan; on this basis, add 0.3g sodium polyphosphate, stir to obtain a uniform solution.

(2) Dissolve 0.3g methacryloyl chitosan derivative in 10mL deionized water, stir to form a uniform solution with a mass fraction of 1.5wt%, and obtain a double bond modified chitosan derivative aqueous solution; on this basis On top, add 0.2g strontium chloride hexahydrate and 5mg photoinitiator, and stir to obtain a uniform solution.

(3) Mix the two obtained solutions at a volume ratio of 1:1. The amino groups on chitosan and the aldehyde groups on xyloglucan react quickly to form Schiff base bonds, obtaining dynamic interactions based on non-covalent interactions. Covalently bonded injectable hydrogels. After the gel is injected into the target position, the double bond polymerization on chitosan is initiated in situ under 405nm blue light irradiation to form a covalent network, thereby constructing a bioactive injectable product based on the double network with easily adjustable modulus. Natural polysaccharide hydrogel for bone repair.

Example 6

Step 1: Preparation of tamarind xyloglucan

(1) Weigh 10g of tamarind powder and dissolve it in 1000mL of deionized water, stir at 40°C for 24h until a viscous solution is formed;

(2) Centrifuge the above viscous solution and take the supernatant to remove insoluble impurities and proteins;

(3) Slowly add the supernatant to excess ethanol to obtain xyloglucan precipitation. After three precipitation processes, the purified xyloglucan raw material can be obtained by drying.

Step 2: Preparation of aldehylated xyloglucan

(1) Weigh 3.0g xyloglucan and dissolve it in 300mL deionized water to obtain a 1.0wt% xyloglucan solution;

(2) Weigh 0.3g of sodium periodate, add it to the above solution, and stir for 2 hours in the dark to perform the oxidation reaction;

(3) Add 0.5 mL of ethylene glycol to the above solution, react for 6 hours, and remove unreacted sodium periodate;

(4) Put the above reacted solution into an 8000D dialysis bag and dialyze it for 3 to 5 days to remove impurities, and freeze-dry to obtain aldehyde-modified xyloglucan.

Step 3: Preparation of methacryloyl chitosan

(1) Weigh 3g of chitosan (deacetylation degree 95%) and place it in 300mL of deionized water, add 4mL of acetic acid dropwise to help dissolve, stir until the chitosan is completely dissolved, and raise the temperature to 60°C;

(2) Add 2 mL of methacrylic anhydride dropwise to the above solution, and react at 60°C for 3 hours;

(3) Add 10wt% sodium bicarbonate aqueous solution dropwise to neutralize excess acid, adjust the pH to 6.5, and stir overnight to reduce the generation of bubbles;

(4) The above-reacted solution was placed in a 8000D dialysis bag and dialyzed for 4 days, and then freeze-dried to obtain methacryloyl chitosan.

Step 4: Preparation of polysaccharide hydrogel

(1) Dissolve 0.2g of aldehyde-modified xyloglucan in 10 mL of deionized water, stir to form a uniform solution with a mass fraction of 6.0 wt%, and obtain an aqueous solution of aldehyde-modified xyloglucan; on this basis, add 0.25g sodium polyphosphate, stir to obtain a uniform solution.

(2) Dissolve 0.3g methacryloyl chitosan derivative in 10mL deionized water, stir to form a uniform solution with a mass fraction of 1.5wt%, and obtain a double bond modified chitosan derivative aqueous solution; on this basis On top, add 0.15g strontium chloride hexahydrate and 5mg photoinitiator, and stir to obtain a uniform solution.

(3) Mix the two obtained solutions at a volume ratio of 1:1. The amino groups on chitosan and the aldehyde groups on xyloglucan react quickly to form Schiff base bonds, obtaining dynamic interactions based on non-covalent interactions. Covalently bonded injectable hydrogels. After the gel is injected into the target position, the double bond polymerization on chitosan is initiated in situ under 405nm blue light irradiation to form a covalent network, thereby constructing a bioactive injectable product based on the double network with easily adjustable modulus. Natural polysaccharide hydrogel for bone repair.

The above are only a few embodiments of the present application, and are not intended to limit the present application in any way. Although the present application is disclosed as above with preferred embodiments, they are not intended to limit the present application. Any skilled person familiar with this field, Without departing from the scope of the technical solution of this application, slight changes or modifications made using the technical content disclosed above are equivalent to equivalent implementation examples and fall within the scope of the technical solution.

Claims (10)

1. A method for preparing a natural polysaccharide hydrogel for bone repair, comprising:

(1) Mixing a solution A containing an aldehyde natural polysaccharide and a solution B containing a double-bond modified chitosan derivative, wherein aldehyde groups in the aldehyde natural polysaccharide and amino groups in the double-bond modified chitosan derivative react with each other through Schiff base to obtain a dynamic covalent network of the polysaccharide hydrogel;

(2) Carrying out addition reaction on the dynamic covalent network of the polysaccharide hydrogel obtained in the step (1) under the irradiation of ultraviolet light to obtain natural polysaccharide hydrogel containing double cross-linked networks and used for bone repair;

the solution A comprises any one of a bone repair promoter and a mixture E;

the solution B comprises the other one of a bone repair accelerant and the mixture E;

the mixture E comprises strontium ions and a photoinitiator.

2. The method according to claim 1, wherein the bone repair agent is at least one selected from the group consisting of polyphosphate and phosphate.

3. The method according to claim 1, wherein the aldehyde-modified natural polysaccharide is at least one selected from aldehyde-modified xyloglucose and aldehyde-modified hyaluronic acid;

the strontium ion is selected from strontium chloride hexahydrate;

the double bond modified chitosan derivative is methacrylated chitosan.

4. The method according to claim 1, wherein the mass ratio of the double bond modified chitosan derivative, the aldehyde-modified natural polysaccharide, the strontium ion and the bone accelerator is 0.5 to 2:1-2:0.1-1.5:0.1-2.

5. The method of claim 1, wherein the method of preparing the aldehyde-modified natural polysaccharide comprises:

and (3) reacting the aqueous solution containing the natural polysaccharide with an oxidant to obtain the aldehyde natural polysaccharide.

6. The method of claim 5, wherein the oxidizing agent is selected from sodium periodate.

7. The method according to claim 5, wherein the concentration of the natural polysaccharide in the aqueous solution containing the natural polysaccharide and the oxidizing agent is 0.5 to 2.0wt%; the concentration of the oxidant is 0.1-3 wt%.

8. The method according to claim 5, wherein the reaction conditions are: and (3) carrying out light-shielding reaction for 2-12 h.

9. A natural polysaccharide hydrogel for bone repair, wherein the natural polysaccharide hydrogel for bone repair is selected from any one of the natural polysaccharide hydrogels for bone repair prepared according to the method of any one of claims 1 to 8.

10. The method of using the natural polysaccharide hydrogel for bone repair according to claim 9, wherein the step (2) of claim 1 is performed under a dark condition to obtain a material G which is not subjected to addition reaction;

injecting the material G which does not undergo addition reaction to a bone defect position, and then adopting ultraviolet irradiation to promote wound healing; or,

and taking the material G as a biological 3D printing raw material, carrying out 3D printing manufacturing by irradiating the material G with ultraviolet light, and placing the material G at a bone defect position.