A hydrogel occluding umbrella for gastric perforation and its preparation method

Abstract

The present invention discloses a hydrogel occluding umbrella for gastric perforation and a preparation method thereof, comprising a occluding portion, wherein both ends of the occluding portion are integrally formed with a fixing portion. The present invention achieves an excellent occluding effect through triple synergy. The spatial mechanical interlocking effect brought about by the double umbrella design provides immediate occlusion, continuous self-expansion and compaction, and the physicochemical adhesion at the tissue-gel interface ensures that a safe and long-lasting gastric perforation sealing effect can be provided under a corrosive gastric fluid environment and dynamic mechanical load. The caffeic acid-modified chitosan component has unique proton adsorption and biomolecule capture properties, which can effectively block the infiltration of digestive enzymes such as gastric acid and pepsin. This protective effect not only maintains the activity of endogenous growth factors in the wound microenvironment, but also creates conditions conducive to tissue regeneration, thereby significantly promoting the healing and repair of gastric perforation.

Description

Technical Field

[0001] The present invention relates to the field of medical technology, in particular to a hydrogel occluding umbrella for gastric perforation and a preparation method thereof. Background Art

[0002] Gastric perforation refers to a full-thickness defect in the gastric wall caused by a variety of causes, including severe peptic ulcers, trauma, malignant tumors, iatrogenic injury, and active perforation during endoscopic surgery. Without timely medical intervention, gastric contents can leak into the abdominal cavity through the perforation, causing acute and severe abdominal pain and systemic inflammation, and even potentially fatal sepsis. Traditional surgical procedures are often highly invasive and carry the risk of serious complications such as anastomotic leakage, wound infection, and postoperative bleeding. In contrast, endoscopic metal clip treatment is a less invasive alternative, but it is difficult to perform, requires extremely high professional skills, and is prone to failure when dealing with inflamed or edematous tissue.

[0003] Over the past few decades, hydrogel-based bioadhesives have become potential materials for gastric perforation repair due to their excellent biocompatibility, tissue adhesion, and biodegradability. These hydrogel formulations include injectable, powder assembly, and preformed types, designed to repair gastric perforations by adhering to the wound site. However, in clinical applications, the mechanical and chemical digestive environments of the stomach pose significant challenges to the performance of hydrogels. Mechanical digestion in the stomach requires that the hydrogel possess structural stability and resistance to mechanical fatigue under the frequent contraction and relaxation of the circular and longitudinal muscles of the gastric wall. Chemical digestion in the stomach requires that the hydrogel maintain adhesion and strength after long-term exposure to gastric acid and digestive enzymes. At the same time, gastric acid, as a strong acid, irritates the wound surface and aggravates inflammation. Digestive enzymes can decompose endogenous growth factors and delay the healing process. Currently, most hydrogels are difficult to effectively protect the wound surface and promote wound healing in the harsh gastric environment.

[0004] The atrial septal occluder, commonly used in cardiology, has been innovatively applied in recent years to treat gastrointestinal perforations and fistulas due to its unique structural design. While its metal structure effectively resists mechanical and chemical digestion in the stomach, its non-degradability requires subsequent surgical removal, which inevitably leads to secondary damage. We have developed a novel biodegradable hydrogel occluder that can be precisely delivered to the lesion site through endoscopy and exhibits excellent biocompatibility and controllable degradation, effectively sealing the defect while promoting tissue healing. Summary of the Invention

[0005] The purpose of the present invention is to provide a hydrogel occluding umbrella for gastric perforation and a preparation method thereof, which solves the problems raised in the background technology.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a hydrogel occluding umbrella for gastric perforation, comprising an occluding part, wherein both ends of the occluding part are integrally formed with a fixing part, the diameter and height of the occluding part are both 5 mm, and the diameter and height of the fixing part are 10 mm and 3 mm, respectively.

[0007] The present invention also relates to a method for preparing a hydrogel occluding umbrella for gastric perforation, comprising the following steps:

[0008] Step 1: dissolving chitosan in deionized water at room temperature and continuously stirring, then dissolving caffeic acid in anhydrous ethanol by ultrasonic treatment to obtain a uniform solution, dissolving 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide in a small amount of deionized water and mixing with the caffeic acid ethanol solution, then adding the activated caffeic acid solution dropwise to the chitosan solution and stirring at room temperature. After the stirring is completed, the obtained solution is dialyzed in deionized water for three days for purification, and then freeze-dried to obtain a caffeic acid-grafted chitosan product, i.e., caffeic acid-modified chitosan;

[0009] Step 2: Add polyacrylamide, caffeic acid-modified chitosan, photoinitiator and N,N'-cystamine bisacrylamide solution to deionized water, then heat to prepare a mixture, and shake the mixture on an oscillator to obtain a transparent caffeic acid-modified chitosan / polyacrylamide solution:

[0010] Step 3: Inject the prepared caffeic acid modified chitosan / polyacrylamide solution into the mold and cure it under ultraviolet light overnight. Finally, take out the prepared hydrogel occluding umbrella and store it in a sterile sealed container.

[0011] As a preferred embodiment of the present invention, the stirring time in step 1 is 48 hours.

[0012] As a preferred embodiment of the present invention, the heating temperature in step 2 is 60° C. and the heating time is 20 minutes.

[0013] As a preferred embodiment of the present invention, the sterile sealed storage temperature condition in step three is 10°C-20°C.

[0014] As a preferred embodiment of the present invention, the photoinitiator is Irgacure 2959.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. The hydrogel occluder adopts a unique double-umbrella design, achieving excellent sealing effect through triple synergy: the rapid spatial mechanical interlocking effect brought by the double-umbrella design, the continuous self-expansion and compaction effect, and the physical and chemical adhesion at the tissue-gel interface. This multiple mechanism ensures that it can still provide a fast, safe and long-lasting gastric perforation sealing effect under the corrosive gastric fluid environment and dynamic mechanical load.

[0017] 2. The caffeic acid-modified chitosan / polyacrylamide component has unique proton adsorption and biomolecule capture properties, which can effectively block the penetration of digestive enzymes such as gastric acid and pepsin. This protective effect not only maintains the activity of endogenous growth factors in the wound microenvironment, but also creates conditions conducive to tissue regeneration, thereby significantly promoting the healing and repair of gastric perforation.

[0018] 3. The mold casting technology can accurately and customizablely prepare hydrogel occluders of various shapes and sizes with good biocompatibility and biodegradability, and is adapted to endoscopic delivery, which helps to repair gastric perforation in various clinical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0020] Figure 1 This is a schematic structural diagram of a hydrogel occluding umbrella for gastric perforation according to the present invention;

[0021] Figure 2 This is a cross-sectional view of a mold for a hydrogel occluding umbrella for gastric perforation according to the present invention;

[0022] Figure 3 is the hydrogen nuclear magnetic resonance spectrum of the present invention;

[0023] Figure 4 is the Fourier transform infrared spectrum of the present invention;

[0024] Figure 5 It is the mechanical performance diagram of the present invention;

[0025] Figure 6 This is the cyclic tension and cyclic compression diagram of the present invention;

[0026] Figure 7 This is the electron microscope structure diagram of the present invention;

[0027] Figure 8 This is the swelling performance diagram of the present invention;

[0028] Figure 9 This is a diagram of the barrier protection and cell migration in vitro of the present invention;

[0029] Figure 10is the in vitro biocompatibility diagram of the present invention;

[0030] Figure 11 The in vivo degradability and blood biochemical profile of the present invention;

[0031] Figure 12 This is a diagram of surgical treatment and endoscopic tracking of rabbit gastric perforation according to the present invention;

[0032] Figure 13 This is a gross image of the rabbit stomach wall tissue after 28 days of treatment with the present invention.

[0033] Figure 14 This is the in vivo X-ray tracing diagram of the present invention;

[0034] Figure 15 This is an immunofluorescence staining image of rabbit stomach wall tissue after 7 days of treatment with the present invention;

[0035] Figure 16 This is an immunohistochemical staining image of rabbit stomach wall tissue after 7 days of treatment with the present invention;

[0036] Figure 17 This is an endoscopic tracking image of the pig stomach wound healing according to the present invention;

[0037] Figure 18 This is the gross tissue and HE section of pig stomach after 28 days of treatment with the present invention;

[0038] Figure 19 This is the biochemical analysis diagram of pig blood and HE slices of important organs of the present invention.

[0039] In the figure: 1, blocking part; 11, fixing part. DETAILED DESCRIPTION

[0040] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0041] A hydrogel occluding umbrella for gastric perforation comprises an occluding portion 1, with fixing portions 11 integrally formed at both ends of the occluding portion 1.

[0042] It should be noted that the diameter and height of the blocking portion 1 are both 5 mm, and the diameter and height of the fixing portion 11 are respectively 10 mm and 3 mm.

[0043] A preparation method of a hydrogel occluding umbrella for gastric perforation is as follows:

[0044] 5 g of chitosan (CS) was dissolved in deionized water at room temperature with continuous stirring. Then, 1.22 g of caffeic acid (CA) was dissolved in anhydrous ethanol by ultrasonic treatment to obtain a homogeneous solution. To activate the carboxyl groups on the caffeic acid, 1.30 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (hereinafter referred to as EDCI) and 0.78 g of N-hydroxysuccinimide were dissolved in a small amount of deionized water and mixed with the caffeic acid ethanol solution. The activated CA solution was then added dropwise to the CS solution and stirred at room temperature for 48 hours. The resulting solution was dialyzed in deionized water for three days for purification and then freeze-dried to obtain the caffeic acid-modified chitosan (CA-CS) product.

[0045] Polyacrylamide PAM (1.8 g), CA-CS (200 mg), photoinitiator Irgacure 2959 (22.4 mg) and N,N'-cystamine bisacrylamide solution (46 μL, 10 mg / mL) were added to 8 mL of deionized water. After heating at 60 °C for about 20 min, the mixture was shaken on a shaker to obtain a transparent CA-CS / PAM solution.

[0046] The polymethyl methacrylate (PMMA) cavity mold was made by injection molding. Its design was inspired by the cardiac atrial septum / ventricular septum occlusion device. The design scheme includes two umbrella-shaped fixing parts and a central occlusion part. The diameter and height of the central part are both 5 mm, and the diameter and height of the end part are 10 mm and 3 mm respectively. The prepared CA-CS / PAM solution was injected into the mold and cured overnight under ultraviolet light (150W). Finally, the prepared hydrogel occlusion umbrella was taken out and placed in a sterile sealed container for storage at 10℃-20℃.

[0047] What needs to be said further is:

[0048] 1. Design and characterization of CA-CS / PAM composite hydrogels

[0049] like Figure 3 As shown, 1H-NMR spectrum suggested that CA was successfully grafted onto CS;

[0050] like Figure 4 As shown in Figure 3, Fourier transform infrared spectroscopy (FTIR) spectrum shows that CA-CS / PAM hydrogel has a new characteristic absorption peak at 1407 cm-1, which is attributed to the aromatic C=C peak of the catechol group rich in phenolic hydroxyl groups in CA-CS. The CA-CS skeleton can effectively dissipate energy, while the soft and ductile PAM network maintains the integrity of the hydrogel during deformation, giving it excellent mechanical properties.

[0051] like Figure 5As shown in Figure 2, CA-CS / PAM hydrogel exhibits significant tensile properties, can be stretched to 20 times its original length, has a breaking strength of 77.18 kPa, and a toughness of 0.62 MJ / m 3 The highest value is the compressive strength of 287.80kPa.

[0052] like Figure 6 As shown in the cyclic tensile and cyclic compression tests, CA-CS / PAM hydrogel exhibited excellent mechanical stability and fatigue resistance, laying a solid foundation for CA-CS / PAM hydrogel to resist fracture or external deformation during dynamic movement of gastric tissue.

[0053] like Figure 7 As shown, it can be seen under an electron microscope that the present invention has a dense microstructure.

[0054] like Figure 8 As shown in the results, CA-CS / PAM hydrogel exhibited rapid swelling behavior, enabling it to quickly fill gastric perforation and exert a self-expansion compaction effect to achieve effective and durable closure. In PBS and SGF solutions, CA-CS / PAM hydrogel swelled rapidly within the first hour, and the swelling ratios after 24 hours reached 500.14% and 580.60%, respectively.

[0055] 2. Wound protection function, biocompatibility and degradability of CA-CS / PAM composite hydrogel

[0056] Gastric acid and digestive proteases can hinder the gastric wound healing process by aggravating tissue damage and degrading factors that promote regeneration, especially basic fibroblast growth factor and vascular endothelial growth factor, which are crucial for angiogenesis and tissue repair. CS has proton adsorption capacity, and the catechol groups in CA have a molecular retention effect on biomacromolecules. CA-CS / PAM hydrogel can protect wounds from gastric juice penetration, thereby retaining endogenous growth factors in the wound bed to promote perforation repair.

[0057] like Figure 9 As shown, a simple transwel l system was developed, in which the hydrogel in the upper chamber blocked the simulated gastric fluid to evaluate the wound protection effect of CA-CS / PAM hydrogel. The cell migration results in the lower chamber showed that after 48 hours, the CA-CS / PAM hydrogel group showed more significant cell migration (67.3±3.4%), compared with the PAM hydrogel group (28.2±2.3%), confirming its ability to effectively prevent gastric acid and pepsin penetration and promote wound healing. These results indicate that CA-CS / PAM hydrogel has unique H+ ion adsorption and biomacromolecule chelation capabilities, which are beneficial for preventing wounds from being exposed to acidic conditions and external decomposition factors (such as pepsin), increasing local growth factor accumulation, and promoting gastric wound healing.

[0058] To further evaluate the long-term protective effect of CA-CS / PAM hydrogel in simulated gastric fluid, a transwell device was used to monitor the permeation of H+ ions and pepsin through the hydrogel barrier. Specifically, pure PAM hydrogel and CA-CS / PAM hydrogel were placed at the bottom of the upper chamber, and an acidic solution (pH = 2.0) and a pepsin solution (2 mg / mL) were added. The pH and pepsin concentration in the lower chamber were systematically monitored every 24 hours. The results showed that as H+ ions freely permeated into the lower chamber, the pH value in the PAM hydrogel steadily decreased, reaching 4.98±0.4 on the third day. In contrast, the CA-CS / PAM hydrogel effectively prevented PBS acidification for at least 7 days, and the acid resistance was proportional to the CS content. Similarly, the CA-CS / PAM hydrogel significantly reduced the diffusion of pepsin, with only 14.32% permeability after 7 days, compared with 83.33% in the PAM hydrogel group. The permeability of pepsin decreased with increasing modified caffeic acid content. These results collectively indicate that the CA-CS / PAM hydrogel can maintain its chemical properties for a long time and withstand long-term exposure to acidic conditions and decomposing enzymes, thereby providing a protective barrier for gastric wounds.

[0059] like Figure 10 As shown, in vitro biocompatibility studies using live / dead cell staining and cell counting kit-8 (CCK-8) assays showed that CA-CS / PAM hydrogel had no significant effect on cell viability compared with the control group.

[0060] like Figure 11 As shown, in vivo degradability and biocompatibility are crucial for effective tissue repair, minimizing complications, and avoiding secondary surgical removal. To this end, we subcutaneously implanted CA-CS / PAM hydrogels (diameter: 1 cm) into rats and collected samples for further evaluation to explore the biodegradability of the hydrogels. The remaining weight of the CA-CS / PAM hydrogels after 12 weeks was significantly reduced to one-fifth of that at week 1. In addition, hematological and biochemical analyses showed that there were no significant differences in complete blood cell counts (CBCs) and biochemical indices between hydrogel-implanted rats and healthy controls for up to 12 weeks, indicating that it has excellent in vivo biocompatibility and that the hydrogel degradation products have no potential systemic toxicity.

[0061] Example 1

[0062] A full-thickness perforation with a diameter of 5 mm was created in the anterior wall of the rabbit stomach by surgical means (e.g. Figure 12 A), and then the perforation was sealed with a hydrogel occluder;

[0063] During the wound healing process, endoscopic examinations were performed on the wounds of the two groups on days 3, 7, 14, and 28. After surgery, the hydrogel occluder rapidly expanded and remained stably fixed at the perforation site for at least three days, effectively blocking the rabbit gastric perforation. Endoscopic follow-up on day 14 showed that the healing effect of the occluder group was better than that of the traditional suture group, which still had mild inflammation ( Figure 12 B), on day 28, there were no obvious unhealed wounds in both groups;

[0064] Examination of gastric tissue collected on day 28 confirmed that the mucosal and serosal surfaces of gastric perforations in both groups had completely healed. H&E staining further showed that the perforated area was completely bridged, indicating that the gastric wall had been fully repaired in both groups on day 28. Figure 13 As shown;

[0065] In order to track the shedding of the hydrogel occluder, we added three metal beads to each of the double umbrella-shaped ends of the hydrogel occluder and observed the position of the hydrogel occluder by X-ray. The hydrogel occluder group remained at the perforation site for the first 5 days and gradually fell off on the 7th day. The gastric part was discharged through the gastrointestinal tract, while the abdominal part remained firmly attached to the original site, as shown in Figure 2. Figure 14 As shown;

[0066] Immunofluorescence staining of the wound site was performed on the 7th day, and the results of CD86 (M1 macrophages) and CD206 (M2 macrophages) immunofluorescence staining showed that compared with the suture group, the hydrogel occlusion umbrella group had the lowest level of M1 macrophages and the highest level of M2 macrophages in the wound on the 7th day, indicating that the wound shifted to an anti-inflammatory phenotype. Figure 15 As shown;

[0067] On the 7th day, the wound site was subjected to immunohistochemistry (IHC) staining to study its efficacy in retaining endogenous growth factors in vivo. The results showed that compared with the suture group, the hydrogel occluder had significantly enhanced expression of bFGF and angiogenesis-promoting VEGF growth factors on the 7th day, and the number of new blood vessels also increased. This was due to the proton adsorption capacity of the chitosan component and the sealing effect of the catechol group in the caffeic acid on the biomacromolecules through nucleophilic reaction, which gave the hydrogel occluder a barrier protection effect on the wound surface, protecting it from the invasion of gastric acid and digestive enzymes, and promoting the repair of gastric perforation. Figure 16 shown.

[0068] Example 2

[0069] A 10 mm diameter perforation was created in the anterior wall of the pig stomach using a Dual knife. Pneumoperitoneum was then created, and the perforation was immediately sealed with a hydrogel occluder. The hydrogel occluder effectively treated the artificial peritoneal gas caused by gastric perforation surgery, demonstrating the occluder's superior sealing effect.

[0070] During the wound healing process, endoscopic examinations were performed on the wounds of the two groups on days 3, 7, 14, and 28. The hydrogel occluder effectively blocked the pig stomach perforation. On day 28, there were no obvious unhealed wounds in both groups. Figure 17 As shown;

[0071] Examination of gastric tissues collected on day 28 confirmed that the mucosal and serosal surfaces of gastric perforations in both groups had completely healed, and H&E staining further showed that the perforated area was completely bridged, indicating that the gastric wall had been fully repaired in both groups on day 28. Figure 18 As shown;

[0072] Blood analysis results on day 28 after treatment were unremarkable, and H&E staining of major organs (heart, liver, spleen, lungs, and kidneys) showed normal tissues with no evidence of inflammation or systemic inflammatory damage secondary to gastric perforation, e.g. Figure 19 shown.

[0073] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be regarded as illustrative and non-restrictive in all respects. The scope of the present invention is defined by the appended claims rather than the foregoing description, and all changes that come within the meaning and range of equivalents of the claims are intended to be included therein.

[0074] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A hydrogel occluding umbrella for gastric perforation, characterized in that: It comprises a blocking portion (1), wherein both ends of the blocking portion (1) are integrally formed with fixing portions (11); The diameter and height of the blocking portion (1) are both 5 mm, and the diameter and height of the fixing portion (11) are respectively 10 mm and 3 mm; The preparation method of the hydrogel occluding umbrella is as follows: Step 1: Chitosan is dissolved in deionized water at room temperature with continuous stirring. Then, caffeic acid is dissolved in anhydrous ethanol by ultrasonic treatment to obtain a uniform solution. 1-Ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide are dissolved in a small amount of deionized water and mixed with the caffeic acid ethanol solution. Subsequently, the activated caffeic acid solution is added dropwise to the chitosan solution and stirred at room temperature. After stirring, the resulting solution is dialyzed in deionized water for three days for purification, and then freeze-dried to obtain a caffeic acid-grafted chitosan product, i.e., caffeic acid-modified chitosan. Step 2: Add polyacrylamide, caffeic acid-modified chitosan, photoinitiator and N,N'-cystamine bisacrylamide solution to deionized water, then heat to prepare a mixture, and shake the mixture on an oscillator to obtain a transparent caffeic acid-modified chitosan / polyacrylamide solution: Step 3: Inject the prepared caffeic acid modified chitosan / polyacrylamide solution into the mold and cure it under ultraviolet light overnight. Finally, take out the prepared hydrogel occluding umbrella and store it in a sterile sealed container.

2. The hydrogel occluder for gastric perforation according to claim 1, characterized in that: The stirring time described in step 1 is 48 hours.

3. The hydrogel occluder for gastric perforation according to claim 1, characterized in that: The heating temperature in step 2 is 60° C. and the heating time is 20 min.

4. The hydrogel occluder for gastric perforation according to claim 1, characterized in that: The sterile sealed storage temperature condition described in step 3 is 10°C-20°C.

5. The hydrogel occluder for gastric perforation according to claim 1, characterized in that: The photoinitiator is Irgacure 2959.

6. The hydrogel occluder for gastric perforation according to claim 1, characterized in that: The mold described in step 3 is a polymethyl methacrylate cavity mold made by injection molding.

7. The hydrogel occluder for gastric perforation according to claim 1, characterized in that: The power of the ultraviolet lamp is 150W.

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