Preparation method of intestinal canal filling temperature-sensitive gel injection for gastrointestinal anastomosis guided by ultrasonic endoscope

Abstract

The invention discloses a preparation method of an intestinal canal filling temperature-sensitive gel injection for gastrointestinal anastomosis guided by an ultrasonic endoscope, and belongs to the technical field of regenerative medicine. According to the specific method, poloxamer, chitosan, polycarbophil, polyvinylpyrrolidone, iohexol and methylene blue are utilized to construct the novel intestinal canal filling temperature-sensitive gel injection. The injection can be injected into the anastomotic intestinal segment of the small intestine by using a conventional nasobiliary drainage tube which is clinically used at present, and the injection becomes viscous immediately under the action of the pH value of the small intestine after injection, so that the injection is inhibited from spreading all around. Meanwhile, the injection is quickly converted into high-strength hydrogel under the action of body temperature, and the hydrogel is adhered to small intestine mucosa to inhibit gel sliding. Therefore, the injection can form a section of gel on a target small intestine section, local immobilization filling and supporting of the target small intestine section are achieved, development can be achieved, the operation difficulty of intestinal tube puncture and stent placement in gastrointestinal anastomosis guided by an ultrasonic endoscope can be greatly reduced, the operation efficiency and the success rate are improved, and the operation cost is reduced. The dosage is less than that of normal saline which is conventionally used clinically, and the effect is better. Moreover, the gel temperature can be reduced by injecting low-temperature normal saline after the operation, so that the gel is thoroughly dissolved into a solution and discharged out of the body, and the phenomenon that the gel remains in the intestinal canal after the operation to cause obstruction is avoided. Therefore, the novel intestinal canal filling temperature-sensitive gel injection has very important clinical practical application value for gastrointestinal anastomosis guided by an ultrasonic endoscope.

Description

Technical Field

[0001] This invention belongs to the field of regenerative medicine technology, and in particular relates to a method for preparing and applying a thermosensitive gel injection solution for intestinal filling in endoscopic ultrasound-guided gastrointestinal anastomosis. Background Technology

[0002] Endoscopic ultrasound-guided gastrointestinal anastomosis (EUS-GE) is a novel interventional treatment technique that combines precise ultrasound localization with minimally invasive endoscopic manipulation. Its core principle involves using real-time imaging guidance from a linear array endoscopic ultrasound system to puncture the distal duodenum or proximal jejunum through the gastric wall. By placing a LAMS (Laminated Endoscopic Mass System) stent, an artificial passage is created between the stomach and jejunum, bypassing the pylorus or duodenal obstruction site, thus restoring the patient's digestive tract patency and oral feeding function. With its significant advantages of minimal trauma, precise operation, rapid recovery, and few complications, this technique has become the optimal treatment option for patients with advanced cancer complicated by gastric outflow tract obstruction, elderly and frail patients, or those with multiple underlying diseases who cannot tolerate traditional open surgery. It opens up a new survival path for these critically ill patients and holds an irreplaceable and important position in the palliative treatment of gastrointestinal obstruction.

[0003] However, the successful implementation of EUS-GE surgery highly depends on the precise puncture of the target intestinal segment during the procedure, and the intestinal puncture operation itself is extremely technically challenging. On the one hand, target intestinal segments such as the jejunum are free-floating segments with active peristalsis and unfixed positions, which can easily shift or spasm due to instrument stimulation during the operation, leading to loss of the puncture target. On the other hand, the intestinal segment is in a collapsed state in its natural state, resulting in poor contrast with the surrounding tissues under ultrasound imaging, making it difficult to clearly distinguish the layers of the intestinal wall and the boundaries of the lumen, further increasing the difficulty of puncture localization. Slight carelessness can lead to serious complications such as puncture failure, intestinal wall perforation, and abdominal infection, significantly affecting the safety and success rate of the operation.

[0004] Therefore, the effectiveness of bowel filling during the procedure is a crucial factor determining the success of bowel puncture. Ideal bowel filling achieves two core objectives: first, it expands and reshapes the collapsed bowel, clearly outlining the lumen boundaries and intestinal wall structure, improving ultrasound image contrast, and helping the surgeon accurately identify the target bowel segment and plan a safe puncture path; second, it maintains the stability of the bowel filling shape, resisting interference from bowel peristalsis and instrument manipulation, and providing a stable operating space for the puncture procedure. Therefore, selecting a suitable bowel filling injection solution and optimizing the filling effect are core technical aspects for improving the success rate of EUS-GE surgery and reducing the incidence of complications.

[0005] Currently, normal saline is routinely used as the intestinal filling injection solution in clinical practice. However, this solution has insurmountable drawbacks that severely restrict the improvement of surgical outcomes. Normal saline has extremely low viscosity and cannot remain in the intestine for extended periods. It is easily lost rapidly due to intestinal peristalsis, requiring repeated injections and very large volumes. This results in poor intestinal filling and stability, not only prolonging surgical time and increasing the risk of intestinal over-distension and injury, but also leading to fluid accumulation in the abdominal cavity, increasing the risk of infection. These shortcomings make normal saline unsuitable for the precise and stable intestinal filling injection requirements of EUS-GE surgery, becoming a bottleneck restricting the further promotion and application of EUS-GE.

[0006] Based on the aforementioned pain points in the intestinal filling process during EUS-GE, developing novel intestinal filling injection solutions has become an urgent technical challenge. Thermosensitive gel, as a type of intelligent polymer material with temperature-responsive properties, exists as a low-viscosity liquid at low temperatures, exhibiting good fluidity and injectability, and can be smoothly injected through the working channel of an endoscopic ultrasound system. Upon entering the body, it rapidly undergoes a sol-gel phase transition at body temperature, forming a gel with a certain strength and adhesion. This characteristic makes it a promising candidate to overcome the inherent limitations of physiological saline. After in vivo injection, the gel can remain in the intestinal tract for an extended period during surgery, more stably maintaining adequate intestinal filling, requiring only a small injection volume and eliminating the need for repeated injections. Furthermore, by loading an ultrasound contrast agent, the gel can achieve high ultrasound contrast, clearly outlining intestinal boundaries. In addition, the gel provides higher intestinal support strength, improving the success rate of intestinal puncture and providing better mechanical support during stent placement, thus better ensuring surgical success. Therefore, developing a thermosensitive gel injection solution for bowel filling in EUS-GE surgery, and improving surgical precision and safety by optimizing its components and ratios, is of great clinical significance and application value in promoting the development of EUS-GE. Summary of the Invention

[0007] To address the aforementioned issues, this invention provides a method for preparing and applying a thermosensitive hydrogel injection solution for intestinal filling in endoscopic ultrasound-guided gastrointestinal anastomosis. The aim is to rapidly form a high-strength hydrogel in the target small intestinal segment after injection, achieving stable and sufficient filling of the target intestinal segment, enabling clear visualization, reducing the difficulty of intestinal puncture and stent placement, and dissolving the gel postoperatively to prevent gel residue from causing obstruction.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solutions.

[0009] This invention discloses a thermosensitive gel injection solution for intestinal filling in endoscopic ultrasound-guided gastrointestinal anastomosis, characterized in that it comprises the following components: poloxamer, chitosan, polycarboxylic acid, polyvinylpyrrolidone, iohexol, and methylene blue.

[0010] Further, the components of the injection solution are: poloxamer, concentration of 22%~30% (w / v); chitosan, concentration of 0.2%~0.6% (w / v); polycarboflavone, concentration of 0.1%~0.5% (w / v); polyvinylpyrrolidone, concentration of 0.4%~2% (w / v); iohexol, concentration of 2%~8% (w / v); and methylene blue, concentration of 0.002%~0.1% (w / v).

[0011] Furthermore, the poloxamer is poloxamer 407, or a mixture of poloxamer 407 and poloxamer 188, with a ratio ranging from 4:1 to 8:1.

[0012] Furthermore, the degree of deacetylation of the chitosan is 95%~99%, and the molecular weight is 10,000~300,000 Da.

[0013] Furthermore, the molecular weight of the polycarboxymethyl methacrylate (PCM) is 2,000,000 to 3,000,000 Da.

[0014] Furthermore, the molecular weight of the polyvinylpyrrolidone is 20,000 to 50,000 Da.

[0015] The present invention also discloses a method for preparing the injection solution described in any one of the above claims, characterized by comprising the following steps: S1. Chitosan solution was added to poloxamer solution under ice bath and stirring conditions, and the mixture was stirred until homogeneous to obtain mixture A; S2. Add the polycarboxymethyl methacrylate solution to mixture A in S1 and stir to mix evenly to obtain mixture B; S3. Add polyvinylpyrrolidone to the mixture B obtained in S2, and stir to mix evenly to obtain mixture C; S4. Add iohexol to the mixture C prepared in S3, and stir to mix evenly to obtain mixture D; S5. Add methylene blue to the mixture D prepared in S4, stir and mix evenly to obtain a thermosensitive gel injection solution for intestinal filling.

[0016] Furthermore, the pH value of the chitosan solution in step S1 is 4.7~6.1.

[0017] The present invention also provides the application of the above-described injection solution as an intestinal filling injection in the preparation of endoscopic ultrasound-guided gastrointestinal anastomosis (EUS-GE).

[0018] The present invention also provides a method for lowering the gel temperature and dissolving it into a liquid by re-injecting low-temperature saline after endoscopic ultrasound-guided gastrointestinal anastomosis (EUS-GE) of any of the above-mentioned injection solutions, thereby avoiding postoperative gel residue in the intestinal tract that could cause obstruction.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows.

[0020] 1. Possesses precise temperature-sensitive and reversible properties, adaptable to surgical procedures and postoperative drainage needs. This injection solution uses poloxamer as its core temperature-sensitive component. At low temperatures, it is a low-viscosity injectable solution that can be smoothly injected through routine nasobiliary drainage tubes. After injection, it rapidly forms a hydrogel in the target small intestine at body temperature, achieving localized stability and fixation of the target intestinal segment. This provides reliable support for puncture positioning and stent placement, reducing surgical difficulty, shortening operation time, and minimizing the risk of intestinal over-distension and injury. Furthermore, the temperature-sensitive properties of poloxamer are reversible. Postoperative injection of low-temperature saline can lower the gel temperature, dissolving it into a solution that facilitates natural drainage from the intestine, effectively avoiding the risk of intestinal obstruction caused by postoperative gel residue and improving surgical safety.

[0021] 2. pH-responsive, inhibiting post-injection diffusion, with significant local gelation and filling effects. This invention introduces chitosan, which can interact with poloxamer intermolecularly, synergistically promoting the temperature-sensitive gelation process. In particular, when the injection solution comes into contact with the weakly alkaline intestinal fluid of the small intestine, chitosan undergoes a deprotonation reaction, further enhancing intermolecular interactions and rapidly increasing the viscosity of the injection solution. This effectively inhibits the diffusion of the injection solution to the surrounding area, precisely focusing on the target small intestinal segment to form a gel, achieving localized immobilization and filling, and significantly improving the support strength for the target small intestinal segment. This provides a more stable space and operating environment for intestinal puncture and stent placement, overcoming the defects of easy diffusion and loss and unstable filling morphology after injection of physiological saline.

[0022] 3. Strong bioadhesion, inhibiting gel slippage and improving the filling stability of the target intestinal segment. The polycarbamide added to the injection solution in this invention can synergistically interact with poloxamer and chitosan, significantly enhancing the bioadhesion of the gel to the small intestinal mucosa. This effectively reduces the relative slippage of the gel during intestinal peristalsis, maintaining the filling shape of the target small intestinal segment for a longer period. It prevents gel slippage due to intestinal peristalsis, thus avoiding weakened filling effect and eliminating the need for supplementary injections.

[0023] 4. The gel network is stable and intact, improving the reliability of intestinal support. The polyvinylpyrrolidone used in this invention can form multi-component intermolecular interactions with poloxamer, chitosan, and polycarboflavone, further optimizing the gel network structure, improving the stability and integrity of the gel network, and enhancing the strength of the gel. This ensures that it can maintain morphological stability under the mechanical stimulation of puncture and stent placement procedures, continuously providing reliable mechanical support for the intestinal tract. This solves the problem that physiological saline has no supporting effect and cannot resist intestinal peristalsis interference.

[0024] 5. The injection solution provides clear and precise imaging, aiding in accurate surgical procedures. The iohexol added to the injection solution of this invention can combine with other components through intermolecular interactions, increasing gel strength and immobilizing the contrast agent on the target small intestinal segment. This prevents the contrast agent from diffusing with the liquid, resulting in blurred imaging. It significantly improves the ultrasound contrast between the target intestinal segment and surrounding tissues, clearly outlining intestinal boundaries, intestinal wall layers, and adjacent vascular structures. This helps surgeons accurately plan the puncture path, avoid risks such as blood vessels and adhesions, and improve the success rate of puncture, overcoming the poor imaging effect of saline.

[0025] 6. The injection solution exhibits excellent biocompatibility and low irritation to the intestinal mucosa. The poloxamer, chitosan, polycarbofil, and polyvinylpyrrolidone used in this invention are all medical-grade biocompatible materials, and the amount of methylene blue is controlled within a safe range. Furthermore, the adhesive properties of chitosan and polycarbofil can form a gentle protective film on the intestinal mucosa surface, reducing the irritation to the intestinal mucosa caused by instrument manipulation and the injection solution. This avoids the problem of physiological saline lacking adhesive protection and easily causing intestinal mucosal inflammation or damage, making it particularly suitable for critically ill patients with fragile intestinal mucosa.

[0026] In summary, this invention, through the synergistic effect of multiple components, comprehensively overcomes the inherent defects of existing saline bowel filling techniques, and has significant advantages in improving the precision, stability, and safety of EUS-GE surgery. It has important clinical significance and application value in promoting the standardization and precision of EUS-GE surgery. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to specific embodiments. However, this should not be construed as limiting the scope of the above-described subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0028] Unless otherwise specified, all reagents and materials used in this invention are commercially available.

[0029] A novel thermosensitive intestinal filling gel injection solution was constructed using poloxamer, chitosan, polycarboflavone, polyvinylpyrrolidone, iohexol, and methylene blue. This injection solution can be injected into the anastomosed segment of the small intestine using a conventional nasobiliary drainage tube. After injection, the solution immediately becomes viscous under the influence of the small intestinal pH, inhibiting its diffusion. Simultaneously, under body temperature, the solution rapidly transforms into a high-strength hydrogel, adhering to the small intestinal mucosa and inhibiting gel slippage. Thus, this injection solution can form a gel segment in the target small intestinal segment, achieving localized fixation, filling, and support of the target intestinal segment, and is visualized. This significantly reduces the difficulty of puncturing the intestinal tract and placing stents during endoscopic ultrasound-guided gastrointestinal anastomosis, improving surgical efficiency and success rate. It requires less volume and achieves better results than conventionally used saline. Furthermore, the gel temperature can be lowered postoperatively by injecting low-temperature saline, allowing the gel to completely dissolve and be excreted, thus preventing postoperative gel residue in the intestinal tract and potential obstruction.

[0030] Example 1.

[0031] Chitosan solution (95% deacetylation, 10000 Da molecular weight) was added to poloxamer (poloxamer 407) solution under ice bath and stirring conditions. The pH of the chitosan solution was 4.7. The mixture was stirred until homogeneous. Then, polycarboflavone (2000000 Da molecular weight) solution was added to the above mixture and stirred until homogeneous. Next, polyvinylpyrrolidone (20000 Da molecular weight) was added and stirred until homogeneous. Then, iohexol was added and stirred until homogeneous. Finally, methylene blue was added and stirred until homogeneous to obtain intestinal filling thermosensitive gel injection solution #1.

[0032] The concentration of poloxamer in this intestinal filling thermosensitive gel injection No. 1 is 22% (w / v), the concentration of chitosan is 0.2% (w / v), the concentration of polycarboflavone is 0.1% (w / v), the concentration of polyvinylpyrrolidone is 0.4% (w / v), the concentration of iohexol is 2% (w / v), and the concentration of methylene blue is 0.002% (w / v).

[0033] In addition, injection solutions with poloxamer concentrations of 21% (w / v), 30% (w / v), and 31% (w / v) were prepared, with other conditions remaining unchanged, thus obtaining three control group solutions, namely #2-#4. First, the injectability of the four injection solutions through the nasobiliary drainage tube was compared. It was found that injection solution #4 had high viscosity and could not be injected, while the other three injection solutions could be injected. Then, injection solutions #1, #2, and #3 were placed in a 37°C water bath. It was found that #2 could not form a gel, while the other two injection solutions could form a gel at body temperature. The gelation time for injection solution #1 was 2 minutes, and the gelation time for injection solution #3 was 1 minute. These experimental results indicate that injection solutions containing 22%–30% (w / v) poloxamer can be injected internally through the nasobiliary drainage tube and can rapidly form a hydrogel at body temperature. Therefore, the optimal concentration of poloxamer is 22%–30% (w / v).

[0034] Example 2.

[0035] Chitosan solution (99% deacetylation, molecular weight 300,000 Da) was added to poloxamer solution (a mixture of poloxamer 407 and poloxamer 188 in a 4:1 ratio) under ice bath and stirring conditions. The pH of the chitosan solution was 6.1. The mixture was stirred until homogeneous. Then, polycarboflavone solution (3,000,000 Da) was added to the mixture and stirred until homogeneous. Next, polyvinylpyrrolidone (50,000 Da) was added and stirred until homogeneous. Then, iohexol was added and stirred until homogeneous. Finally, methylene blue was added and stirred until homogeneous to obtain intestinal filling thermosensitive gel injection solution #1.

[0036] The total concentration of poloxamer in this intestinal filling thermosensitive gel injection No. 1 is 30% (w / v), the concentration of chitosan is 0.6% (w / v), the concentration of polycarboflavone is 0.5% (w / v), the concentration of polyvinylpyrrolidone is 2% (w / v), the concentration of iohexol is 8% (w / v), and the concentration of methylene blue is 0.1% (w / v).

[0037] In addition, chitosan injection solutions with concentrations of 0% (w / v), 0.1% (w / v), 0.2% (w / v), and 0.7% (w / v) were prepared, with other conditions remaining unchanged, thus obtaining four control group solutions, numbered 2-5. First, the injectability of the five injection solutions through the nasobiliary drainage tube was compared. It was found that injection solution 5 had high viscosity and could not be injected, while the other four injection solutions could be injected. Next, injection solutions 1-4 were placed in a 37°C water bath. It was found that all four injection solutions could form a gel at a temperature-sensitive rate. The gelation time for injection solutions 2 and 3 was 1.5 min, for injection solution 4 it was 1 min, and for injection solution 1 it was 0.5 min. This indicates that the gelation rate of the 0.1% (w / v) chitosan injection solution was the same as that of the chitosan-free injection solution. Only chitosan concentrations of 0.2% (w / v) and above have a promoting effect on gelation, and the higher the chitosan concentration, the faster the gelation. Then, a 20cm section of small intestine from a Bama miniature pig was taken, longitudinally dissected, spread out on a 45° inclined surface, and fixed. 1mL of each of the above-mentioned low-temperature injection solutions (1#, 2#, 3#, and 4#) was added dropwise to the surface of the small intestine at the top of the slope using the same procedure. The distances the four injection solutions traveled across the intestinal surface were compared. Since the intestinal surface contains weakly alkaline intestinal fluid, this method was used to assess the degree to which injection solutions containing different chitosan concentrations inhibited diffusion at the pH value of the small intestine, thus determining the local immobilization ability of the injection solutions; a shorter flow distance was better. The experiment showed that at 10 seconds after addition, injection solutions 2# and 3# both flowed to the bottom of the slope with no difference between them. Injection solution 4# flowed 15cm across the slope, while injection solution 1# flowed 4cm. This inclined flow experiment demonstrates that the pH response of 0.1% (w / v) chitosan injection is the same as that of chitosan-free injection. At concentrations too low, it cannot inhibit the diffusion of the injection solution in the small intestine's pH environment after injection. Only chitosan concentrations of 0.2% (w / v) and above significantly increase the viscosity upon contact with intestinal fluid, thus inhibiting the diffusion of the injection solution. Furthermore, the higher the chitosan concentration, the more pronounced the diffusion-inhibiting effect. Based on the above experiments, the optimal concentration of chitosan is 0.2%–0.6% (w / v).

[0038] Example 3.

[0039] Chitosan solution (97% deacetylation, molecular weight 150,000 Da) was added to poloxamer solution (a mixture of poloxamer 407 and poloxamer 188 in an 8:1 ratio) under ice bath and stirring conditions. The pH of the chitosan solution was 5.4. The mixture was stirred until homogeneous. Then, polycarboflavone solution (molecular weight 2,500,000 Da) was added to the mixture and stirred until homogeneous. Next, polyvinylpyrrolidone (molecular weight 35,000 Da) was added and stirred until homogeneous. Then, iohexol was added and stirred until homogeneous. Finally, methylene blue was added and stirred until homogeneous to obtain intestinal filling thermosensitive gel injection solution #1.

[0040] The total concentration of poloxamer in this intestinal filling thermosensitive gel injection No. 1 is 26% (w / v), the concentration of chitosan is 0.4% (w / v), the concentration of polycarboflavone is 0.3% (w / v), the concentration of polyvinylpyrrolidone is 1.2% (w / v), the concentration of iohexol is 5% (w / v), and the concentration of methylene blue is 0.05% (w / v).

[0041] In addition, injection solutions of polycarboxymethyl methacrylate (PCBM) at concentrations of 0% (w / v), 0.1% (w / v), 0.5% (w / v), and 0.6% (w / v) were prepared, with other conditions remaining unchanged, thus obtaining four control group solutions, namely #2-#5. First, the injectability of the above five injection solutions through the nasobiliary drainage tube was compared. It was found that injection solution #5 had high viscosity and could not be injected, while the other four injection solutions could be injected. Next, 40 cm of small intestine from a Bama miniature pig was taken, fixed to a 45° inclined surface, and the intestinal tube and slope were placed in a 37°C water bath. 20 mL of the above-mentioned low-temperature injection solutions #1, #2, #3, and #4 were injected into the small intestinal lumen at the top of the slope using the same procedure. The distance from the gel formed by these four injection solutions in the small intestine to the bottom of the intestinal lumen was compared. A longer distance indicates greater adhesion of the gel to the intestinal wall, making it less likely to slide downwards, which is beneficial for fixing the filled intestinal segment. The experiment showed that at 10 minutes after addition, injection solution #2 flowed to the bottom of the slope, injection solution #3 flowed to 1 / 4 of the way from the bottom, injection solution #1 flowed to 1 / 3 of the way from the bottom, and injection solution #4 flowed to 1 / 2 of the way from the bottom. This slope flow experiment indicates that the adhesiveness of the polycarboxylic acid-free gel is very low and cannot inhibit its sliding in the intestinal tract. Only polycarboxylic acid concentrations of 0.1% (w / v) and above have a significant inhibitory effect on gel sliding in the intestinal tract, and the higher the concentration of polycarboxylic acid, the more obvious the inhibitory effect on gel sliding. Based on the above experiment, the optimal concentration of polycarboxylic acid is 0.1%~0.5% (w / v).

[0042] Example 4.

[0043] Chitosan solution (96% deacetylation, molecular weight 50,000 Da) was added to poloxamer solution (a mixture of poloxamer 407 and poloxamer 188 in a 6:1 ratio) under ice bath and stirring conditions. The pH of the chitosan solution was 5.8. The mixture was stirred until homogeneous. Then, polycarboflavone solution (molecular weight 2,800,000 Da) was added to the mixture and stirred until homogeneous. Next, polyvinylpyrrolidone (molecular weight 28,000 Da) was added and stirred until homogeneous. Then, iohexol was added and stirred until homogeneous. Finally, methylene blue was added and stirred until homogeneous to obtain intestinal filling thermosensitive gel injection solution #1.

[0044] The total concentration of poloxamer in this intestinal filling thermosensitive gel injection No. 1 is 24% (w / v), the concentration of chitosan is 0.5% (w / v), the concentration of polycarboflavone is 0.2% (w / v), the concentration of polyvinylpyrrolidone is 1.6% (w / v), the concentration of iohexol is 3% (w / v), and the concentration of methylene blue is 0.01% (w / v).

[0045] In addition, injection solutions with polyvinylpyrrolidone concentrations of 0% (w / v), 0.3% (w / v), 0.4% (w / v), 2% (w / v), and 2.1% (w / v) were prepared, with other conditions remaining unchanged, thus obtaining five control group solutions, numbered 2-6. First, the injectability of the six injection solutions through the nasobiliary drainage tube was compared. It was found that injection solution 6 had high viscosity and could not be injected, while the other five injection solutions could be injected. Next, the compressive stress of the hydrogels formed by injection solutions 1-5 at 37°C was tested using a universal testing machine. The experiment showed that the compressive stress of gels 2 and 3 was the same, 3N, indicating that the compressive stress of 0.3% (w / v) polyvinylpyrrolidone was the same as that of 0% (w / v), indicating that the concentration was too low. However, the compressive stress of gel 4 was 5N, gel 1 was 8N, and gel 5 was 9N, indicating that the gel strength increased with increasing polyvinylpyrrolidone concentration. Furthermore, 30 mL of solutions 1-5 were injected into the target duodenum of Bama miniature pigs. It was found that the intestinal segments supported by gels 2 and 3 experienced local collapse during puncture and stent placement, affecting the procedure. In contrast, gels 4, 1, and 5 provided greater support, preventing intestinal collapse during puncture and stent placement, thus completing the anastomosis. Additionally, postoperative injection of 150 mL of low-temperature saline into the gel sites revealed that gels 4, 1, and 5 were dissolved by ultrasound, with no gel residue remaining. Therefore, these experiments demonstrate that the optimal concentration of polyvinylpyrrolidone is 0.4%–2% (w / v), and the injection solution is beneficial for EUS-GE procedures.

[0046] Example 5.

[0047] Chitosan solution (98% deacetylation, molecular weight 270,000 Da) was added to poloxamer solution (a mixture of poloxamer 407 and poloxamer 188 in a 5:1 ratio) under ice bath and stirring conditions. The pH of the chitosan solution was 5.0. The mixture was stirred until homogeneous. Then, polycarboflavone solution (molecular weight 2,200,000 Da) was added to the mixture and stirred until homogeneous. Next, polyvinylpyrrolidone (molecular weight 45,000 Da) was added and stirred until homogeneous. Then, iohexol was added and stirred until homogeneous. Finally, methylene blue was added and stirred until homogeneous to obtain intestinal filling thermosensitive gel injection solution #1.

[0048] The total concentration of poloxamer in this intestinal filling thermosensitive gel injection No. 1 is 28% (w / v), the concentration of chitosan is 0.3% (w / v), the concentration of polycarboflavone is 0.4% (w / v), the concentration of polyvinylpyrrolidone is 0.6% (w / v), the concentration of iohexol is 7% (w / v), and the concentration of methylene blue is 0.08% (w / v).

[0049] In addition, injection solutions with concentrations of 0% (w / v), 1% (w / v), 2% (w / v), 8% (w / v), and 9% (w / v) of iohexol were prepared, with other conditions remaining unchanged, thus obtaining five control group solutions, numbered 2-6. First, the injectability of the six injection solutions through the nasobiliary drainage tube was compared. It was found that injection solution 6# had high viscosity and could not be injected, while the other five injection solutions could be injected. Next, the compressive stress of the hydrogels formed by injection solutions 1-5# at 37°C was tested using a universal testing machine. The experiment showed that the compressive stress of gels 2# and 3# was the same, at 4N, indicating that the compressive stress of 1% (w / v) iohexol was the same as that of 0% (w / v), indicating that the concentration was too low. However, the compressive stress of gel 4# was 6N, gel 1# was 11N, and gel 5# was 12N, indicating that the gel strength increased with increasing iohexol concentration. Furthermore, 40 mL of solutions 1-5 were injected into the target jejunum of Bama miniature pigs. It was found that the intestinal segments supported by gels 2 and 3 experienced local collapse during puncture and stent placement, affecting the surgical procedure. Additionally, the contrast between the gels and surrounding tissues was low, resulting in weak imaging ability. However, gels 4, 1, and 5 provided greater intestinal support; puncture and stent placement did not cause intestinal collapse, the anastomosis was completed, and the gel imaging ability was significantly enhanced, with a clear difference in contrast with surrounding tissues. Subsequently, 200 mL of low-temperature saline was injected into the gel sites postoperatively. Ultrasound revealed that gels 4, 1, and 5 were dissolved, with no gel residue. Therefore, the above experiments indicate that the optimal concentration of iohexol is 0.4%–2% (w / v). With increasing concentration, the gel strength increases, the support for the intestinal segment is enhanced, and the imaging ability is significantly improved, which is beneficial for EUS-GE procedures.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A thermosensitive gel injection solution for intestinal filling in endoscopic ultrasound-guided gastrointestinal anastomosis, characterized in that, It includes the following components: poloxamer, chitosan, polycarbofibril, polyvinylpyrrolidone, iohexol, and methylene blue.

2. The injection solution as described in claim 1, characterized in that, The components of the injection solution are: poloxamer, concentration 22%~30% (w / v); chitosan, concentration 0.2%~0.6% (w / v); polycarbofi, concentration 0.1%~0.5% (w / v); polyvinylpyrrolidone, concentration 0.4%~2% (w / v); iohexol, concentration 2%~8% (w / v); and methylene blue, concentration 0.002%~0.1% (w / v).

3. The injection solution as described in claim 1, characterized in that, The poloxamer is poloxamer 407, or a mixture of poloxamer 407 and poloxamer 188, with a ratio ranging from 4:1 to 8:

1.

4. The injection solution as described in claim 1, characterized in that, The degree of deacetylation of the chitosan is 95%~99%, and the molecular weight is 10,000~300,000 Da.

5. The injection solution as described in claim 1, characterized in that, The molecular weight of the polycarboxymethyl methacrylate (PCM) is 2,000,000 to 3,000,000 Da.

6. The injection solution as described in claim 1, characterized in that, The molecular weight of the polyvinylpyrrolidone is 20,000 to 50,000 Da.

7. A method for preparing the injection solution according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Chitosan solution was added to poloxamer solution under ice bath and stirring conditions, and the mixture was stirred until homogeneous to obtain mixture A; S2. Add the polycarboxymethyl methacrylate solution to mixture A in S1 and stir to mix evenly to obtain mixture B; S3. Add polyvinylpyrrolidone to the mixture B obtained in S2, and stir to mix evenly to obtain mixture C; S4. Add iohexol to the mixture C prepared in S3, and stir to mix evenly to obtain mixture D; S5. Add methylene blue to the mixture D prepared in S4, stir and mix evenly to obtain a thermosensitive gel injection solution for intestinal filling.

8. The method as described in claim 7, characterized in that, The pH value of the chitosan solution in step S1 is 4.7~6.

1.

9. The use of the injection solution according to any one of claims 1 to 6 as an intestinal filling injection in the preparation of endoscopic ultrasound-guided gastrointestinal anastomosis (EUS-GE).

10. The injection solution according to any one of claims 1 to 6 is used to lower the gel temperature and dissolve it into a liquid by re-injecting low-temperature saline after endoscopic ultrasound-guided gastrointestinal anastomosis (EUS-GE), so as to avoid postoperative gel residue in the intestinal tract causing obstruction.