Polysaccharide fluid hydrogel for digestive tract submucous injection and preparation method thereof

Abstract

The invention discloses polysaccharide fluid hydrogel for digestive tract submucous injection and a preparation method of the polysaccharide fluid hydrogel, and belongs to the field of medical biological materials. According to the invention, carboxylated chitin or a carboxylated chitosan derivative with a mass percentage of 0.1-6%, or hydroxyalkylated chitin or a hydroxyalkylated chitosan derivative and collagen or gelatin are subjected to micro-crosslinking to form a low-crosslinking-degree supramolecular derivative as a solute; the polysaccharide fluid hydrogel is formed by taking water, normal saline, a physiological equilibrium solution, a phosphate buffer solution or a Green's solution as a solvent. By controlling the molar ratio of the raw materials to the cross-linking agent and performing micro-crosslinking with a small amount of the cross-linking agent, the prepared low-crosslinking-degree supramolecular derivative can form hydrogel in an aqueous solvent, has shear thinning and self-repairing characteristics, has certain viscosity, is easy to push and inject, and can be applied to the field of water treatment. The lifting height of the mucous membrane can be effectively kept, the height keeping time can be effectively prolonged, the mucous membrane is not prone to overflowing under the condition that the mucous membrane is damaged, an endoscope injection device is not blocked, and the material is an ideal material for forming a safe liquid pad through digestive tract submucous injection.

Description

Technical Field

[0001] The invention relates to a medical biomaterial, in particular to a fluid hydrogel for submucosal injection of the digestive tract and a preparation method and application thereof. Background Art

[0002] Endoscopic submucosal dissection (ESD) is an effective and widely performed minimally invasive method for removing early-stage tumor lesions in the digestive tract. It has the characteristics of small surgical trauma, overall resection of the lesion, and low local recurrence rate. However, it has technical risks such as perforation, positive margin, and intraoperative and postoperative bleeding. Therefore, before ESD, liquid needs to be injected between the mucosal layer and the muscularis propria at the lesion site to physically separate the mucosal layer and the submucosal muscularis layer, forming a submucosal liquid cushion buffer, effectively separating and lifting the mucosal layer from the underlying muscularis layer, and providing a "safety liquid cushion" for the underlying muscularis layer. It also improves the visibility of the lesion edge, making the operation easier to perform, and avoiding damage to the submucosal muscularis layer during mucosal dissection, which can cause serious complications such as bleeding and perforation.

[0003] At present, the most commonly used submucosal injection liquid in clinical practice is normal saline, which has the advantages of easy injection, low price and good safety. However, normal saline is a small molecule solution, which is quickly absorbed and diffused in the submucosal layer. The submucosal liquid cushion formed has weak support and short duration. Multiple injections are required during surgery to maintain the height of the lesion, which may increase the difficulty of surgery and increase the potential surgical risks. Therefore, it is necessary to develop a new submucosal injection liquid that can effectively increase the height of the lesion and prolong the support time to provide a long-lasting and safe liquid cushion protection for ESD. The ideal submucosal injection liquid needs to have good submucosal lifting, long duration, good biocompatibility, hemostatic performance, easy injection, and low cost. There are many studies on macromolecular viscous solutions such as sodium hyaluronate, carboxymethyl chitosan, sodium carboxymethyl cellulose, and sodium alginate. When used as a submucosal injection liquid material, the viscous solution of sodium hyaluronate has the characteristics of good submucosal injection lifting and long duration, but the viscous solution of sodium hyaluronate has high viscosity and high injection pressure, which is not conducive to injection. In the invention patent application CN111991620 A, a viscous liquid composed of hyaluronic acid, carboxymethyl chitosan, etc. is used as a submucosal injection liquid. By reducing the concentration of hyaluronic acid and adding carboxymethyl chitosan, the injectability of the liquid is improved, and a thick submucosal liquid cushion can be provided. However, the liquid cushion formed by the viscous liquid is easy to overflow in the case of mucosal damage, and the supporting capacity is greatly reduced. Generally, high-viscosity liquids have better submucosal lifting effects and prolong the duration of lifting, but high-viscosity liquids also increase the injection pressure, causing injection difficulties. There are also reports on the study of thermosensitive hydrogels providing long-lasting liquid cushion protection for ESD during submucosal injection. The master's thesis "Preliminary Study on Thermosensitive Repair Gel for ESD Surgery" reported that the prepared chitosan / collagen / sodium glycerophosphate hydrogel has temperature-sensitive properties, can flow at low temperatures (0~4℃), can be injected at room temperature, and can gel in situ 2~12min after heating to 37℃. However, as mentioned above, the thermosensitive hydrogel is injected at room temperature and gels in situ at 37°C human body temperature for 2 to 12 minutes. It can be foreseen that if the operation time is slightly extended, the thermosensitive gel will gel in the push tube, which may block the endoscopic injection device, limiting its actual clinical operation application. Therefore, as a submucosal injection material, it is necessary to be free from the restrictions of the clinician's operation time, not block the push tube, and maintain good mucosal lifting performance. The injection material also needs to have self-healing properties so that it does not overflow due to mucosal damage during ESD surgery, thereby reducing its mucosal support capacity. Summary of the invention

[0004] In view of the above problems, the first object of the present invention is to provide a polysaccharide fluid hydrogel for submucosal injection of the digestive tract that has good viscosity, is easy to push, has self-healing properties, effectively maintains the mucosal lifting height and lifting time, and does not block the endoscopic injection device, so as to make up for the shortcomings of the prior art.

[0005] Another object of the present invention is to provide a method for preparing a polysaccharide fluid hydrogel for submucosal injection into the digestive tract, and the use of the polysaccharide fluid hydrogel in preparing a biomaterial for submucosal injection into the digestive tract to form a liquid cushion buffer zone.

[0006] The technical solution of the present invention, while taking into account the safety and non-toxicity of the polysaccharide fluid hydrogel for submucosal injection of the digestive tract, focuses on solving the performance balance problems of the hydrogel's viscosity, injection resistance, mucosal lifting retention time, and non-overflow in the event of mucosal damage through micro-cross-linking technology, so as to obtain a polysaccharide fluid hydrogel for submucosal injection of the digestive tract that has good viscosity, is easy to push, effectively maintains the mucosal lifting height and lifting time, is not prone to overflow in the event of mucosal damage, and does not block the endoscopic injection device.

[0007] The polysaccharide fluid hydrogel for tissue separation for submucosal injection of the digestive tract of the present invention is a polysaccharide fluid hydrogel using carboxylated chitosan derivatives or carboxylated chitosan derivatives as raw materials, or using hydroxyalkylated chitosan derivatives or hydroxyalkylated chitosan derivatives and collagen or gelatin as raw materials, and forming low cross-linking degree supramolecular derivatives through micro-crosslinking. The carboxylated chitosan derivatives or carboxylated chitosan derivatives form supramolecular derivatives through hydrogen bonds or ionic interactions between molecules, and the hydroxyalkylated chitosan or hydroxyalkylated chitosan derivatives can also form supramolecular derivatives through intermolecular hydrogen bond interactions between molecules of collagen or gelatin. The supramolecular derivatives are further controlled by micro-crosslinking of a crosslinking agent to form a chemical crosslinking network with a low crosslinking degree, which is the main component of the hydrogel. The polysaccharide fluid hydrogel forms supramolecular derivatives through intermolecular interactions, and then the low cross-linking degree of the polymer chemical cross-linked network formed by micro-cross-linking control, the two are combined with each other, and can be dissolved in the water system solvent to form a fluid hydrogel with viscosity, and has good water retention capacity, and because its hydrophilicity is lower than that of the uncross-linked raw material, it has a certain viscosity and fluidity. Due to the existence of hydrogen bond interactions between molecules, the fluid hydrogel has fluidity and self-repairability, and also has the shear thinning characteristics due to external forces, so the resistance of the polysaccharide fluid hydrogel during the push injection process is reduced, and it is easy to push. The low cross-linking degree of the polymer chemical cross-linked network superimposes the hydrogen bond interactions between molecules, and the low cross-linking degree supramolecular derivatives can also form hydrogen bonds and self-repairing effects with biological macromolecules such as body tissue proteins, so that there is good adhesion between body tissues, and it is not easy to overflow due to mucosal damage. The low cross-linking supramolecular derivative in the polysaccharide fluid hydrogel is controlled by micro-crosslinking, and its absorption speed in the body tissue is slow, and the micro-crosslinking grid has a strong ability to retain water molecules. Therefore, as a submucosal injection material, it can effectively maintain the lifting height of the mucosa and prolong the height retention time, effectively play the role of the liquid cushion, and separate the tissue. Therefore, the carboxylated chitosan derivative or carboxylated chitosan derivative molecules form supramolecular derivatives through hydrogen bonds or ionic interactions, or the hydroxyalkylated chitosan or hydroxyalkylated chitosan derivative can also form supramolecular derivatives with collagen or gelatin through intermolecular hydrogen bond interactions, and further micro-crosslinking with a cross-linking agent can obtain a polysaccharide fluid hydrogel for submucosal injection of the digestive tract that has good viscosity, is easy to push, effectively maintains the mucosal lifting height and lifting time, is not easy to overflow in the case of mucosal damage, and does not block the endoscopic injection device, thereby solving the shortcomings of the prior art.

[0008] The specific technical solutions of the present invention are as follows: A polysaccharide fluid hydrogel for submucosal injection of the digestive tract, characterized in that it is a polysaccharide fluid hydrogel formed by using 0.1-6% by mass of carboxylated chitosan or carboxylated chitosan derivatives, or hydroxyalkylated chitosan or hydroxyalkylated chitosan derivatives and collagen or gelatin, a low cross-linking degree supramolecular derivative formed by micro-crosslinking as a solute, and water, physiological saline, physiological equilibrium solution, phosphate buffer or Ringer's solution as a solvent, wherein the cross-linking degree of the low cross-linking degree supramolecular derivative is 0.1-6% by mole percentage based on the mole number of the polysaccharide raw material.

[0009] The carboxylated chitosan or carboxylated chitosan derivatives include but are not limited to carboxymethyl chitosan, carboxyethyl chitosan, carboxymethyl chitosan, carboxyethyl chitosan, succinyl chitosan, carboxymethyl succinyl chitosan, carboxyethyl succinyl chitosan; the hydroxyalkylated chitosan or hydroxyalkylated chitosan derivatives include one or more of hydroxyethyl chitosan, hydroxypropyl chitosan, hydroxybutyl chitosan, hydroxyethyl chitosan, hydroxypropyl chitosan, and hydroxybutyl chitosan. The low cross-linked supramolecular derivative is a low cross-linked supramolecular derivative prepared by micro-crosslinking of the above-mentioned carboxylated chitosan or chitosan derivatives, or hydroxyalkylated chitosan or chitosan derivatives with collagen or gelatin through a cross-linking agent.

[0010] The polysaccharide fluid hydrogel for submucosal injection in the digestive tract has shear thinning and self-repairing properties.

[0011] The method for preparing the polysaccharide fluid hydrogel for submucosal injection of the digestive tract includes the preparation of a low-crosslinking supramolecular derivative and the preparation of a fluid hydrogel, and specifically includes the following steps: (1) Preparation of low cross-linking supramolecular derivatives: weigh raw materials carboxylated chitin or carboxylated chitosan derivatives, or hydroxyalkylated chitin or hydroxyalkylated chitosan derivatives and collagen or gelatin, wherein the mass ratio of hydroxyalkylated chitin or hydroxyalkylated chitosan derivatives to collagen or gelatin is 1:0.05-0.5, add water and stir to dissolve; calculate the molar number of the polysaccharide raw material, according to the molar ratio of the polysaccharide raw material to the cross-linking agent of 100:0.1-6, add the cross-linking agent, adjust the pH of the solution, and stir to react for 12-24 hours; after the reaction, ethanol precipitation, washing, dehydration with anhydrous ethanol, and drying are performed to obtain a low cross-linking supramolecular derivative; (2) Weigh a low-crosslinking supramolecular derivative, dissolve it in water, physiological saline, physiological equilibrium solution, phosphate buffer or Ringer's solution, and prepare a hydrogel with a mass percentage concentration of 0.1-6%. Control the dynamic viscosity of the hydrogel to be 1-400 Pa.s, put it into an injection bottle or syringe, and sterilize it by wet heat or irradiation to obtain a polysaccharide fluid hydrogel.

[0012] In the above-mentioned method for preparing the polysaccharide fluid hydrogel for submucosal injection of the digestive tract, the cross-linking agent includes but is not limited to one of glycidyl ethers (butylene glycol diglycidyl ether, polyethylene glycol glycidyl ether, ethylene glycol diglycidyl ether, glycerol triglycidyl ether, hexanediol diglycidyl ether, etc.), carbodiimide (EDAC, EDC, EDCI or DCC used in combination with NHS, HOBt or HOAt), and DMTMM.

[0013] The polysaccharide fluid hydrogel for submucosal injection in the digestive tract is used in the preparation of biomaterials for forming a liquid cushion buffer zone for submucosal injection.

[0014] The raw materials selected by the present invention have excellent biosafety and degradation absorbability, and have no toxic side effects on the human body. By controlling the molar ratio of the raw material to the cross-linking agent, a small amount of cross-linking agent is used for micro-cross-linking, and the prepared low-cross-linking supramolecular derivative can form a hydrogel in an aqueous solvent. The dynamic viscosity of the hydrogel liquid is controlled at 1~400 Pa.s, and there is a polymer chemical cross-linking network with a low cross-linking degree formed by micro-cross-linking control, and a supramolecular structure composed of dynamic reversible interactions of intermolecular hydrogen bonds. Therefore, the hydrogel has shear thinning and self-repairing properties, has a certain viscosity, is easy to push, and can effectively maintain the lifting height of the mucosa and extend the height retention time, and is not easy to overflow in the case of mucosal damage, does not block the endoscopic injection device, and is an ideal fluid hydrogel material for submucosal injection of the digestive tract to form a safe liquid pad. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a graph showing the viscosity of the polysaccharide fluid hydrogel 4 of the present invention as a function of shear rate.

[0016] Figure 2 This is a self-healing test diagram of the polysaccharide fluid hydrogel 2 of the present invention.

[0017] Among them, the left picture is an orange-dyed hydrogel; the middle picture is an undyed hydrogel; and the right picture shows two parts of hydrogel of different colors healed into a whole.

[0018] Figure 3 This is a self-healing test diagram of the polysaccharide fluid hydrogel 4 of the present invention.

[0019] Among them, the left picture is an undyed hydrogel; the middle picture is a blue-dyed hydrogel; and the right picture shows two parts of hydrogel of different colors healed into a whole.

[0020] Figure 4 This is a test chart of the mucosal lifting ability of the polysaccharide fluid hydrogel injected submucosally. DETAILED DESCRIPTION

[0021] The present invention will be further described in detail below through specific embodiments.

[0022] Example 1: Preparation of carboxylated chitosan derivatives with low cross-linking degree supramolecular derivative 1 Weigh 9.6 g of carboxymethyl chitosan, stir and dissolve in 400 mL of deionized water, add 0.062 g of carbodiimide crosslinker EDC and 0.046 g of NHS at a molar ratio of carboxymethyl chitosan to crosslinker of 100:1, stir and dissolve, adjust the pH to 5.0, and react at room temperature for 24 h. Add about 4 times the volume of anhydrous ethanol to the reaction system to precipitate the reactant, filter, wash with 75% ethanol, dehydrate with anhydrous ethanol, and heat to dry at 60°C to obtain a carboxylated chitosan derivative with a low crosslinking degree supramolecular derivative 1.

[0023] Example 2: Preparation of carboxylated chitosan derivative with low cross-linking degree supramolecular derivative 2 Weigh 11 g of carboxymethyl chitosan, stir and dissolve it in 400 mL of deionized water, add 0.248 g of carbodiimide crosslinker EDC and 0.184 g of NHS at a molar ratio of carboxymethyl chitosan to crosslinker of 100:4, stir and dissolve, adjust the pH to 6.0, and react at room temperature with stirring for 18 h; add about 4 times the volume of anhydrous ethanol to the reaction system to precipitate the reactant, filter, wash with 75% ethanol, dehydrate with anhydrous ethanol, and heat and dry at 60°C to obtain a carboxylated chitosan derivative with a low crosslinking degree supramolecular derivative 2.

[0024] Example 3: Preparation of Hydroxypropylated Chitosan Derivative-Gelatin Low Crosslinking Degree Supramolecular Derivative 3 Weigh 5.2 g of hydroxypropyl chitosan and 2 g of gelatin, stir and dissolve in 400 mL of deionized water, add 0.004 ml of cross-linking agent 1, 4-butanediol glycidyl ether at a molar ratio of hydroxypropyl chitosan to cross-linking agent of 100:0.1, stir and dissolve, adjust the pH to 9.0, and react at room temperature for 24 h; add about 4 times the volume of anhydrous ethanol to the reaction system to precipitate the reactant, filter, wash with 75% ethanol, dehydrate with anhydrous ethanol, and heat to dry at 60°C to obtain hydroxypropyl chitosan derivative-gelatin low cross-linking supramolecular derivative 3.

[0025] Example 4: Preparation of hydroxyethylated chitosan derivative-collagen low cross-linking supramolecular derivative 4 Weigh 6.3 g of hydroxyethyl chitosan and 0.4 g of collagen, stir and dissolve in 400 mL of deionized water, add 0.28 g of carbodiimide crosslinker EDC and 0.21 g of NHS at a molar ratio of hydroxyethyl chitosan to crosslinker of 100:6, stir and dissolve, adjust the pH to 5.0, and react at room temperature for 12 h; add about 4 times the volume of anhydrous ethanol to the reaction system to precipitate the reactant, filter, wash with 80% ethanol, dehydrate with anhydrous ethanol, and heat to dry at 60°C to obtain hydroxyethylated chitosan derivative-collagen low crosslinking supramolecular derivative 4.

[0026] In the above embodiments 1 to 4, the carboxylated chitosan or carboxylated chitosan derivatives include but are not limited to carboxymethyl chitosan, carboxyethyl chitosan, carboxymethyl chitosan, carboxyethyl chitosan, succinyl chitosan, carboxymethyl succinyl chitosan, and carboxyethyl succinyl chitosan; the hydroxyalkylated chitosan or hydroxyalkylated chitosan derivatives include one or more of hydroxyethyl chitosan, hydroxypropyl chitosan, hydroxybutyl chitosan, hydroxyethyl chitosan, hydroxypropyl chitosan, and hydroxybutyl chitosan. The carboxylated chitosan / chitosan derivative has carboxyl, amino and hydroxyl groups in its molecular structure; the hydroxyalkylated chitosan or carboxylated chitosan derivative has amino and hydroxyl groups in its molecular structure; the composition of the hydroxyalkylated chitosan or hydroxyalkylated chitosan derivative and collagen or gelatin has amino, hydroxyl and carboxyl groups, wherein the hydroxyalkylated chitosan or hydroxyalkylated chitosan derivative is the main component, and the mass ratio of the hydroxyalkylated chitosan or hydroxyalkylated chitosan derivative to the collagen or gelatin is 1:0.05~0.5; the above chemical structure can undergo cross-linking reaction with a glycidyl ether cross-linking agent, and can also undergo cross-linking reaction with a carbodiimide carboxyl or amino condensation agent to prepare a low cross-linking degree supramolecular derivative.

[0027] In the above embodiments 1 to 4, the crosslinking agent includes but is not limited to one of glycidyl ether (butylene glycol diglycidyl ether, polyethylene glycol glycidyl ether, ethylene glycol diglycidyl ether, glycerol triglycidyl ether, hexanediol diglycidyl ether, etc.), carbodiimide (EDAC, EDC, EDCI or DCC used in combination with NHS, HOBt or HOAt), and DMTMM. The molar ratio of the polysaccharide raw material to the crosslinking agent is 100:0.1-6, forming a polymer chemical crosslinking network with a low degree of crosslinking.

[0028] Example 5: Preparation of polysaccharide fluid hydrogel Weigh 1.5 g of the low-crosslinked supramolecular derivative 1 of the carboxylated chitosan derivative prepared in Example 1, dissolve it in 150 ml of physiological saline, adjust the pH to 7.0, prepare a hydrogel with a percentage concentration of 1%, and sterilize it with wet heat. The sterilized hydrogel is divided into two parts, one part is measured by a rotational viscometer to have a dynamic viscosity of 8.5 Pa.s, and the other part is loaded into a syringe to obtain a polysaccharide fluid hydrogel 1.

[0029] Weigh 3 g of the low-crosslinked supramolecular derivative 2 of the carboxylated chitosan derivative prepared in Example 2, dissolve it in 150 ml of physiological saline, adjust the pH to 6.5, prepare a hydrogel with a concentration of 2%, and sterilize it with wet heat. The sterilized hydrogel is divided into two parts, one part is measured by a rotational viscometer to have a dynamic viscosity of 48.9 Pa.s, and the other part is loaded into a syringe to obtain a polysaccharide fluid hydrogel 2.

[0030] Weigh 0.5 g of the hydroxypropylated chitosan derivative-gelatin low cross-linking supramolecular derivative 3 prepared in Example 3, dissolve it in 150 ml of water, adjust the pH to 8.0, prepare a hydrogel with a concentration of 0.33%, sterilize it with wet heat, and divide the sterilized hydrogel into two parts. One part has a dynamic viscosity of 1.5 Pa.s as measured by a rotational viscometer, and is loaded into a syringe to obtain a fluid hydrogel 3.

[0031] 6 g of the hydroxyethylated chitosan derivative-collagen low cross-linking supramolecular derivative 4 prepared in Example 4 was weighed and dissolved in 150 ml of phosphate buffer (0.2 M), the pH was adjusted to 7.6, and a hydrogel with a percentage concentration of 4% was prepared. The hydrogel was sterilized by wet heat. The sterilized hydrogel was divided into two parts. One part had a dynamic viscosity of 336 Pa.s as measured by a rotational viscometer and was loaded into a syringe to obtain a fluid hydrogel 4.

[0032] Example 6: Shear-thinning property test of polysaccharide fluid hydrogel Take polysaccharide fluid hydrogel 4 and measure its shear thinning properties on a rheometer. Figure 1 It can be observed that with the increase of the shear rate of the rheometer, the viscosity of the hydrogel shows a significant and rapid downward trend. This phenomenon reflects that the hydrogel has typical shear thinning properties. Due to the shear thinning properties, when the polysaccharide fluid hydrogel is loaded into a syringe and the gel is pushed out of the syringe, it can be observed that the pushing process is smooth and there is no great push resistance.

[0033] Example 7: Self-healing test of polysaccharide fluid hydrogel (1) Self-healing test of polysaccharide fluid hydrogel 2: Take 2 portions of polysaccharide fluid hydrogel 2, each with 4 ml, add 2 drops of orange neutral pen ink to one portion, stir evenly, and dye the hydrogel orange. Inject 2 portions of polysaccharide fluid hydrogel 2 of different colors into two five-pointed star-shaped molds respectively. After removing the molds, cut the two five-pointed stars of different colors into two parts from the midline position, and then put the two parts of different colors side by side. It can be observed that the two parts of different colors heal into a whole, indicating that polysaccharide fluid hydrogel 2 has self-healing properties, see Figure 2 .

[0034] (2) Self-healing test of polysaccharide fluid hydrogel 4: Take 2 portions of 4 ml each of fluid hydrogel 4, add 2 drops of dark blue gel pen ink to one portion, stir evenly, and dye the hydrogel blue. Inject 2 portions of fluid hydrogel 4 of different colors into two heart-shaped molds respectively. After removing the molds, cut the two hearts of different colors into two parts from the midline position, and then put the two parts of different colors side by side. It can be observed that the two parts of different colors heal into a whole, indicating that polysaccharide fluid hydrogel 4 has self-healing properties, see Figure 3 .

[0035] Example 8: Testing of mucosal lifting ability of polysaccharide fluid hydrogel submucosal injection The upper third of the pig stomach is similar in thickness to the human stomach and is often used to evaluate the ability of submucosal injection to lift the mucosa. The upper third of fresh pig stomach was cut into 5 × 5 cm squares and randomly divided into a normal saline control group, a polysaccharide fluid hydrogel 2 test group, a polysaccharide fluid hydrogel 3 test group, and a polysaccharide fluid hydrogel 4 test group. 2 mL of normal saline, polysaccharide fluid hydrogel 2, polysaccharide fluid hydrogel 3, and polysaccharide fluid hydrogel 4 were injected into the gastric submucosal layer with a syringe to form a raised liquid cushion. The submucosal injection of the hydrogels in each group was smooth and easy to push out. The initial height of the liquid cushion (0 h) and the height of the liquid cushion after being kept at 37 ° C for 2 h were measured. The results are shown in Figure 2. Figure 1 . It can be seen that physiological saline, fluid hydrogel 2, fluid hydrogel 3, and fluid hydrogel 4 can all form a raised liquid cushion when initially injected into the gastric submucosal layer (0h); but 2h after injection, the physiological saline absorption block, the liquid cushion is absorbed and becomes flat; while fluid hydrogel 2, fluid hydrogel 3, and fluid hydrogel 4 can still maintain a raised liquid cushion 2h after submucosal injection, so that the mucosa and the submucosal muscle layer are clearly separated. At 2h after injection, the liquid cushion height of the physiological saline group was only 12.5% ​​of the initial height, and the liquid cushion heights of fluid hydrogels 2, 3, and 4 were 80.1%, 75.2%, and 89.2% of the initial height, respectively. Figure 4 .

[0036] The above embodiments show that the present invention uses the carboxylated chitin or carboxylated chitosan derivatives, or hydroxyalkylated chitosan or hydroxyalkylated chitosan derivatives and collagen or gelatin, and is micro-crosslinked by the crosslinking reaction of a crosslinking agent to prepare a low crosslinking supramolecular derivative, and the prepared low crosslinking supramolecular derivative is dissolved in an aqueous solvent to form a polysaccharide fluid hydrogel, and the polysaccharide fluid hydrogel is injected into the submucosal to form a liquid pad, wherein the low crosslinking supramolecular derivative has a slow absorption rate in the mucosal tissue and a strong ability to retain water molecules, so the polysaccharide fluid hydrogel can effectively maintain the lifting height of the mucosa and extend the height retention time. Due to micro-crosslinking, the polysaccharide fluid hydrogel has viscosity, is easy to push, effectively maintains the mucosal lifting height and lifting time, has self-repairability, and the mucosal damage is not easy to overflow and does not block the endoscopic injection device. Therefore, the polysaccharide fluid hydrogel of the present invention can be used in the preparation of biomaterials for submucosal injection to form a liquid pad buffer for digestive tract tissue separation, and has great application potential.

Claims

1. A polysaccharide fluid hydrogel for submucosal injection in the digestive tract, characterized in that: The polysaccharide fluid hydrogel is formed by using 0.1-6% by mass of carboxylated chitosan derivatives or carboxylated chitosan derivatives, or hydroxyalkylated chitosan derivatives and collagen or gelatin, a low cross-linking supramolecular derivative formed by micro-crosslinking as a solute, and water, physiological saline, physiological equilibrium solution, phosphate buffer or Ringer's solution as a solvent. The cross-linking degree of the low cross-linking supramolecular derivative is 0.1-6% by mole percentage based on the mole number of the polysaccharide raw material.

2. The polysaccharide fluid hydrogel according to claim 1, characterized in that The carboxylated chitosan derivative or carboxylated chitosan derivative includes carboxymethyl chitosan, carboxyethyl chitosan, carboxymethyl chitosan, carboxyethyl chitosan, succinyl chitosan, carboxymethyl succinyl chitosan or carboxyethyl succinyl chitosan.

3. The polysaccharide fluid hydrogel according to claim 1, characterized in that The hydroxyalkylated chitosan derivative or hydroxyalkylated chitosan derivative includes one or more of hydroxyethyl chitosan, hydroxypropyl chitosan, hydroxybutyl chitosan, hydroxyethyl chitosan, hydroxypropyl chitosan and hydroxybutyl chitosan.

4. A method for preparing a polysaccharide fluid hydrogel for submucosal injection in the digestive tract, characterized in that: The following steps are involved: (1) Preparation of low cross-linking supramolecular derivatives: weigh raw materials carboxylated chitosan derivatives or carboxylated chitosan derivatives, or hydroxyalkylated chitosan derivatives or hydroxyalkylated chitosan derivatives and collagen or gelatin, wherein the mass ratio of the hydroxyalkylated chitosan derivatives or hydroxyalkylated chitosan derivatives to collagen or gelatin is 1:0.05-0.5, add water and stir to dissolve; calculate the molar number of the polysaccharide raw material, according to the molar ratio of the polysaccharide raw material to the cross-linking agent of 100:0.1-6, add the cross-linking agent, adjust the pH of the solution, and stir to react for 12-24 hours; after the reaction, ethanol precipitation, washing, dehydration with anhydrous ethanol, and drying are performed to obtain low cross-linking supramolecular derivatives; (2) Weigh a low-crosslinking supramolecular derivative, dissolve it in water, physiological saline, physiological equilibrium solution, phosphate buffer or Ringer's solution, and prepare a hydrogel with a mass percentage concentration of 0.1-6%. Control the dynamic viscosity of the hydrogel to be 1-400 Pa.s, put it into an injection bottle or syringe, and sterilize it by wet heat or irradiation to obtain a polysaccharide fluid hydrogel.

5. The method for preparing the polysaccharide fluid hydrogel according to claim 4, characterized in that: The cross-linking agent is one of glycidyl ether, carbodiimide and DMTMM.

6. The method for preparing the polysaccharide fluid hydrogel according to claim 5, characterized in that: The glycidyl ether is one of butanediol diglycidyl ether, polyethylene glycol glycidyl ether, ethylene glycol diglycidyl ether, glycerol triglycidyl ether and hexanediol diglycidyl ether.

7. The method for preparing the polysaccharide fluid hydrogel according to claim 5, characterized in that: The carbodiimide is EDAC, EDC, EDCI or DCC used in combination with NHS, HOBt or HOAt.

8. Use of the polysaccharide fluid hydrogel for submucosal injection of the digestive tract according to claim 1 in the preparation of a biomaterial for forming a liquid pad for submucosal injection.

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