Endoscopic marking hydrogel as well as preparation method and application thereof

Abstract

The invention discloses endoscope marking hydrogel as well as a preparation method and application thereof. The preparation method comprises the following steps: dissolving an alkaline compound in a solvent, and stirring until the alkaline compound is completely dissolved to obtain a uniform and stable solution; dissolving dopamine hydrochloride (DA.HCl) in the solution, and stirring until the dopamine hydrochloride is completely dissolved; and then adding a high polymer, and reacting completely to obtain the endoscope labeling hydrogel. The endoscopic marking hydrogel prepared by the invention has excellent adhesion performance and good biocompatibility, and can be applied to safe and efficient accurate positioning of pathological changes or specific parts in gastrointestinal tracts.

Description

Technical Field

[0001] The invention belongs to the field of biomedical materials and relates to a natural polysaccharide complex, specifically the preparation and application of an endoscope marking hydrogel. Background Art

[0002] Endoscopic technology plays an important role in the diagnosis and treatment of the digestive tract, and also in the diagnosis and treatment of tumors, such as injection of markers, tumor therapeutic drugs, etc. In addition, it also plays a vital role in helping oncologists to conduct regular follow-up observations of unresectable lesions, and assisting surgeons in locating difficult-to-detect lesions during laparoscopic surgery, such as small or flat tumors, diverticula, and arteriovenous malformations. However, endoscopic technology still has limitations in the implementation process, and lesion localization is difficult, which is often affected by changes in patient position or organ movement. The difference between colonoscopy results and intraoperative visualization results (especially intestinal lesions) ranges from 6.38% to 21.03%, which highlights the urgent need for accurate preoperative lesion localization in current clinical practice.

[0003] Currently, commonly used endoscopic marking dyes include India ink, indocyanine green (ICG), methylene blue, and sterile carbon compounds (such as SPOT), all of which have associated limitations. India ink has a complex composition, solvents that can easily cause inflammation or allergic reactions, and require meticulous dilution and sterilization, limiting its application. Although ICG is a safer alternative to India ink, it provides poor marking durability and cannot be used in patients who are allergic to iodine. Methylene blue is injected topically under the mucosa for positioning, a process that tends to dissipate and fade rapidly. Ideally, surgery should be started within 2 hours of staining. However, this method has a significant possibility of positioning failure and requires surgery to be completed in the presence of an open abdomen, resulting in the loss of effective positioning function. SPOT is the only FDA-approved drug that is considered safe and durable, but its high cost hinders widespread clinical use. Therefore, there is a clear need for an endoscopic marking dye that is both cost-effective, biosafe, and durable.

[0004] Endoscopic marker hydrogel is a method of marking gastrointestinal lesions with dyes under endoscopy (including endoscopic ultrasound), which can guide subsequent surgical resection of lesions or regular review of lesion diagnosis and treatment. Compared with another commonly used lesion localization method before surgery - endoscopic marker fluid, endoscopic marker hydrogel is less likely to be inaccurately positioned due to displacement. Summary of the invention

[0005] The technical problem to be solved by the present invention is that the materials in the prior art are poorly positioned inside the body, highly toxic and have a short retention time.

[0006] In order to solve the above problems, the present invention provides a method for preparing an endoscopic marking hydrogel, which is characterized by comprising the following steps:

[0007] The alkaline compound is dissolved in a solvent and stirred to completely dissolve it to obtain a uniform and stable solution; dopamine hydrochloride (DA·HCl) is dissolved in the above solution and stirred to completely dissolve it; and then a polymer is added, and after the reaction is complete, an endoscope marking hydrogel is obtained.

[0008] Preferably, the solvent is any one of distilled water, phosphate buffer solution (pH=7.4), and physiological saline (w / v=0.9%); the concentration of dopamine hydrochloride after dissolution is 0.1-10 mol / L; and the dissolution temperature of dopamine hydrochloride is 10-50°C.

[0009] Preferably, the alkaline compound is any one of sodium bicarbonate, sodium hydroxide, ammonia water, potassium hydroxide and calcium hydroxide; the concentration of the dissolved alkaline compound is 0.5-5 mol / L; and the dissolution temperature of the alkaline compound is 0-20°C.

[0010] Preferably, the reaction temperature is 0-50°C.

[0011] Preferably, the reaction time is 2 to 8 hours.

[0012] Preferably, the polymer is konjac glucomannan (KGM), guar gum (GG) and carrageenan (KC); the mass concentration or volume concentration of the polymer in the mixed solution is 1% to 10%.

[0013] The present invention also provides an endoscopic marking hydrogel prepared by the above method, and use of the endoscopic marking hydrogel in preparing a safe and efficient material for accurately positioning lesions or specific parts in the gastrointestinal tract.

[0014] The invention adds dopamine hydrochloride and a co-crosslinked polymer into an alkaline solution. Taking sodium bicarbonate as an alkaline compound and konjac glucomannan as a co-crosslinked polymer as an example, a method for preparing an endoscope marking hydrogel is provided: sodium bicarbonate is dissolved in a solvent, stirred evenly, dopamine hydrochloride is added to react completely, and konjac glucomannan is added to continue the reaction to obtain a conjugated polymer-based composite material.

[0015] The invention utilizes the property that dopamine can self-polymerize under alkaline conditions and provides a preparation method for synthesizing hydrogel by polydopamine and konjac glucomannan under the alkaline conditions of sodium bicarbonate.

[0016] The invention has a simple process, a short product preparation time, and the obtained product has good biocompatibility in both in vivo and in vitro simulation experiments. Different from the previous preparation method of directly dispersing carbon powder in a solvent, the invention selects KGM, GG and KC as stabilizers, and dopamine as a monomer, and uses alkaline conditions to polymerize dopamine.

[0017] KGM is a natural neutral polysaccharide with good biocompatibility, water solubility and excellent gel properties. When dissolved in an alkaline solution, the ester bonds of KGM will be hydrolyzed into hydroxyl groups, which can form intramolecular and intermolecular hydrogen bonds. In an alkaline solution, dopamine can be polymerized to form PDA, while KGM can be hydrolyzed and converted into thermally irreversible KGM hydrogel. Considering the biocompatibility of KGM, this multifunctional hydrogel system is expected to play a huge transformation potential in clinical therapeutic applications. Sodium bicarbonate, also known as baking soda, is weakly alkaline when dissolved in water and can be used as a leavening agent in the food production process. It has the advantage of being non-toxic compared to other alkaline compounds. In the present invention, no other organic solvents are required to participate in the dopamine polymerization process, which embodies the concept of "solvent-free" in green chemistry. Experiments show that the material prepared by the present invention has good adhesion, biosafety and long-term retention in the body.

[0018] Compared with the existing technology, the present invention has significant technical progress. The preparation process of the present invention is simple, the product is easy to obtain, has excellent in vivo lesion marking ability, good positioning ability and the ability to improve the retention time of the mark, can make up for the shortcomings of the existing marking materials such as low utilization efficiency and high toxicity, and is expected to be applied to the fields of safe and efficient accurate positioning of gastrointestinal lesions or specific parts, and has certain clinical application value.

[0019] The present invention also provides the above application as accurate positioning of gastrointestinal lesions or specific parts. The endoscopic marking hydrogel prepared by the present invention has excellent adhesion and good biocompatibility, and can be used for safe and efficient accurate positioning of gastrointestinal lesions or specific parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A is a FESEM image of the endoscopy-labeled hydrogel prepared in Example 1;

[0021] Figure 1 B is a FESEM image of the endoscopy-labeled hydrogel prepared in Example 2;

[0022] Figure 1 C is a FESEM image of the endoscopy-labeled hydrogel prepared in Example 3;

[0023] Figure 2 A is a schematic diagram of the swelling kinetics curves of the endoscope marking hydrogel prepared in Example 1 in physiological saline, simulated gastric fluid, and simulated intestinal fluid;

[0024] Figure 2 B is a schematic diagram of the degradation kinetics curve of the endoscopy marker hydrogel prepared in Example 1 in physiological saline, simulated gastric fluid, and simulated intestinal fluid;

[0025] Figure 3 A is a schematic diagram of the in vitro injectable endoscopic marker hydrogel prepared in Example 1;

[0026] Figure 3 B is a schematic diagram of the in vitro injectable endoscopic marker hydrogel prepared in Example 2;

[0027] Figure 3 C is a schematic diagram of the in vitro injectable endoscopic marker hydrogel prepared in Example 3;

[0028] Figure 3 D is a schematic diagram of the in vitro injectable endoscopic marker hydrogel prepared in Example 4;

[0029] Figure 3 E is a schematic diagram of the in vitro injectable endoscopy-labeled hydrogel prepared in Example 5;

[0030] Figure 3 F is a schematic diagram of the in vitro injectable endoscopic marker hydrogel prepared in Example 6;

[0031] Figure 4 A is the rheological properties of the endoscopy marking hydrogel prepared in Example 1;

[0032] Figure 4 B is the mechanical properties of the endoscope marking hydrogel prepared in Example 1;

[0033] Figure 5 A is a thermal imaging image of the endoscopic marker hydrogels with different concentrations prepared in Example 1;

[0034] Figure 5 B is the endoscopy marker hydrogels with different concentrations prepared in Example 1 (power 1 W / cm 2 Temperature variation curve of 808nm laser irradiation;

[0035] Figure 5 C is the thermal imaging picture of the endoscopic marker hydrogel prepared in Example 1 at different powers;

[0036] Figure 5 D is the temperature change curve of the endoscopic marking hydrogel prepared in Example 1 under 808 nm laser irradiation of different powers;

[0037] Figure 5 E is a photothermal cycle diagram of the endoscopic labeling hydrogel prepared in Example 1;

[0038] Figure 5F is a diagram of the photothermal conversion efficiency of the endoscope-labeled hydrogel prepared in Example 1;

[0039] Figure 6 A is ABTS treated with different concentrations of endoscopy-labeled hydrogel prepared in Example 1 + The UV-visible absorption spectrum after ;

[0040] Figure 6 B is the ABTS of the endoscopy-labeled hydrogel prepared in Example 1 + Clearance rate;

[0041] Figure 6 C is the UV-visible absorption spectra of the endoscopy-labeled hydrogels prepared in Example 1 after being treated with DPPH· at different concentrations;

[0042] Figure 6 D is the DPPH clearance rate of the endoscopy-labeled hydrogel prepared in Example 1;

[0043] Figure 7 A is the hemolysis test result of the endoscope marking hydrogel prepared in Example 1;

[0044] Figure 7 B is the survival rate of fibroblasts after co-culture with the endoscopy-labeled hydrogel prepared in Example 1;

[0045] Figure 7 C is the DEAD / LIVE staining result of fibroblasts after co-culture with the endoscopically labeled hydrogel prepared in Example 1;

[0046] Figure 8 H&E staining results of the biosafety of the endoscopically labeled hydrogel prepared in Example 1 in Kunming mice;

[0047] Fig. 9 A is the in vivo labeling result of the endoscopic labeling hydrogel prepared in Example 1, i.e., endoscopic images of the rectum, esophagus and stomach of a pig model at 0, 15 and 60 days after the use of the labeling hydrogel (red arrow);

[0048] Fig. 9 B is the H&E staining result of the endoscopic marking hydrogel prepared in Example 1 on the pig rectum, esophagus and stomach 60 days after endoscopic tattooing. DETAILED DESCRIPTION

[0049] In order to make the present invention more clearly understood, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0050] Example 1

[0051] Dissolve NaHCO3 (0.4 g) in 30 mL of deionized water, add DA·HCl (0.4 g), place at room temperature, and stir for 4 h. After the reaction is complete, add KGM (0.2 g) to continue the reaction to obtain PDA endoscopy marking hydrogel.

[0052] Example 2

[0053] Dissolve NaOH (0.4 g) in 30 mL of deionized water, add DA·HCl (0.4 g), place at room temperature, and stir for 4 h. After the reaction is complete, add KGM (0.2 g) to continue the reaction to obtain PDA endoscopy marking hydrogel.

[0054] Example 3

[0055] KOH (0.4 g) was dissolved in 30 mL of deionized water, and DA·HCl (0.4 g) was added, and the mixture was stirred at room temperature for 4 h. After the reaction was complete, KGM (0.2 g) was added to continue the reaction, and the PDA endoscope marking hydrogel was obtained.

[0056] Example 4

[0057] LiOH (0.4 g) was dissolved in 30 mL of deionized water, and DA·HCl (0.4 g) was added, and the mixture was stirred at room temperature for 4 h. After the reaction was complete, KGM (0.2 g) was added to continue the reaction, and the PDA endoscope marking hydrogel was obtained.

[0058] Example 5

[0059] Dissolve NaHCO3 (0.4 g) in 30 mL of deionized water, add DA·HCl (0.4 g), place at room temperature, and stir for 4 h. After the reaction is complete, add GG (0.2 g) to continue the reaction to obtain PDA endoscopy marking hydrogel.

[0060] Example 6

[0061] Dissolve NaHCO3 (0.4 g) in 30 mL of deionized water, add DA·HCl (0.4 g), place at room temperature, and stir for 4 h. After the reaction is complete, add KC (0.2 g) to continue the reaction to obtain PDA endoscopy marking hydrogel.

[0062] Example 7

[0063] The endoscopy marking hydrogels in Example 1, Example 2 and Example 3 were freeze-dried and their morphologies were analyzed. The samples were analyzed on a FEI Magellan 400 field emission scanning electron microscope.

[0064] From the electron microscope images, we can see that KGM( Figure 1 A) GG( Figure 1 B) KC( Figure 1 C) all show a porous structure.

[0065] Example 8

[0066] Weigh 40 mg of the freeze-dried endoscopy marker hydrogel in Example 1, and use a swelling test to determine the swelling rate of the hydrogel. Place the freeze-dried hydrogel in a centrifuge tube, pour 20 mL of saline, simulated solution, and simulated intestinal fluid (n=3) into each tube, and incubate at 37°C. When the predetermined time interval is reached, remove the hydrogel from the solution and use filter paper to absorb the surface moisture. Finally, weigh the hydrogel and draw the corresponding swelling kinetic curve. Figure 2 A It can be seen that the endoscopic marker hydrogel has a suitable swelling rate and reaches a balanced state after swelling for 12 hours in the simulated gastric fluid and simulated intestinal fluid environment. The above results prove that the hydrogel can effectively absorb tissue exudate and maintain a relatively moist wound environment. The degree of swelling of the hydrogel in simulated gastric fluid and simulated intestinal fluid is higher than that in physiological saline. Therefore, under physiological pH conditions, the hydrogel can avoid excessive compression and mechanical damage to the tissue.

[0067] Example 9

[0068] Weigh 40 mg of the freeze-dried endoscopy marker hydrogel in Example 1, and soak the freeze-dried hydrogel in 20 mL of physiological saline, simulated gastric fluid, and simulated intestinal fluid (n=3), respectively. Incubate at 37°C, take out the hydrogel samples at fixed time intervals, wash with deionized water to remove impurities, and use filter paper to absorb the surface moisture, then freeze-dry and weigh, and draw the corresponding in vitro degradation curve.

[0069] Depend on Figure 2 B It can be seen that the hydrogel degrades slowly in the simulated gastric fluid and simulated intestinal fluid environments, proving that it has suitable degradation properties under physiological pH conditions.

[0070] Example 10

[0071] 1 mL of the labeled hydrogel of Example 1 was taken and injected with an injection needle in vitro to simulate the injectable condition. Figure 3 As can be seen from A, the labeled hydrogel is darker in color and can be injected through a needle, making it suitable for labeling.

[0072] Embodiment 11

[0073] 1 mL of the labeled hydrogel of Example 2 was taken and injected in vitro using an injection needle to simulate the injectable condition. Figure 3 As can be seen from B, the labeled hydrogel is darker in color and can be injected through a needle, making it suitable for labeling.

[0074] Example 12

[0075] 1 mL of the labeled hydrogel of Example 3 was taken and injected with an injection needle in vitro to simulate the injectable condition. Figure 3 C It can be seen that the labeled hydrogel is darker in color and can be injected through a needle, which is suitable for labeling.

[0076] Example 13

[0077] 1 mL of the labeled hydrogel of Example 4 was taken and injected with an injection needle in vitro to simulate the injectable condition. Figure 3 D shows that the labeled hydrogel is darker in color and can be injected through a needle, making it suitable for labeling.

[0078] Embodiment 14

[0079] 1 mL of the labeled hydrogel of Example 5 was taken and injected in vitro using an injection needle to simulate the injectable condition. Figure 3 As can be seen from E, the labeled hydrogel is dark in color and can be injected through a needle, making it suitable for labeling.

[0080] Embodiment 15

[0081] 1 mL of the labeled hydrogel of Example 6 was taken and injected with an injection needle in vitro to simulate the injectable condition. Figure 3 As can be seen from F, the labeled hydrogel is darker in color and can be injected through a needle, making it suitable for labeling.

[0082] Example 16

[0083] Rheological properties of hydrogels The rheological properties of the endoscopic marker hydrogels were evaluated using a rotational rheometer (MARS III Haake). 200 μL of KGM hydrogel precursor solution was placed between parallel plates with a diameter of 20 mm and a gap of 1.0 mm. The storage modulus and loss modulus were analyzed by time sweep tests at 37 °C, a fixed frequency of 1 Hz, and a strain of 1%. Figure 4 AAfter adding KGM, the storage modulus and loss modulus separated at 10 seconds, and the storage modulus was greater than the loss modulus, indicating that the compound formed a hydrogel.

[0084] Embodiment 17

[0085] Mechanical properties of hydrogels The mechanical properties of hydrogels were evaluated using a universal material testing machine (Zwick Roell Z2.5TH with 2.5 kN sensor). In the experiment, hydrogels were prepared in cylindrical molds with a diameter of 8 mm and a height of 4 mm. The compressive properties of the hydrogels were measured at a predetermined compressive strain rate of 0.5 mm / min. Figure 4 As shown in B, the compressive strength of the hydrogel is 1338.16±68.31KPa).

[0086] Embodiment 18

[0087] Using distilled water as a control, 100 μL of Case 1 labeled hydrogel was dispersed in a 96-well cell culture plate, and the material in the well was irradiated with a near-infrared laser (808 nm) (5 min). The concentration (2.5 mg / mL, 5 mg / mL, 10 mg / mL and 20 mg / mL) and power (0.3 W / cm 2 , 0.6W / cm 2 , 0.8W / cm 2 and 1W / cm 2 ) on the temperature rise (△T) of the material. The photothermal conversion efficiency of the material is measured by using a laser (1W / cm 2 , 808nm) to continuously irradiate the material (20mg / mL, 5min), then cool naturally (5min), and calculate the photothermal efficiency of the material. The material was irradiated for 5 cycles using the on and off near-infrared laser (808nm, 1W / cm 2 , on and off for 5 minutes respectively) to study the photothermal stability of the material. The near-infrared laser used in this test is a high-power multi-mode pump laser produced by Shanghai Kangnei Fiber Optics Co., Ltd. The monitoring of material temperature changes and the shooting of infrared thermal imaging images are performed using FLIR TM E60 infrared camera (FLIR, USA).

[0088] like Figure 5 A and 5B, the materials have absorption in the near-infrared region and have photothermal conversion properties similar to those of pure polydopamine, and this light absorption has significant concentration dependence. Figure 5 As shown in C and 5D, as the laser power decreases, the heat generated gradually decreases, and the corresponding △T is 18℃, 21.8℃, 24.2℃, and 32.8℃, respectively. Figure 5 E. In the 5 illumination cycles (laser on for 5 min / laser off for 5 min), the △T of the material solution did not change significantly. Figure 5 As shown in F, under the irradiation of 808nm infrared laser, the photothermal conversion efficiency of the sample is 28.37%, which is higher than that of common metal photothermal conversion materials.

[0089] Embodiment 19

[0090] The in vitro antioxidant capacity of the endoscopy-labeled hydrogel was evaluated. First, 2,2'-azobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) powder was dissolved to obtain ABTS stock solution (7.4 mM), which was then mixed evenly with the prepared 2.6 mM potassium persulfate (K2S2O8) solution and allowed to react in the dark for 12 h to obtain dark green ABTS free radicals (ABTS + ) solution. Then, ABTS +The solution was diluted with anhydrous ethanol to form a mixture with an absorbance of 0.837 at 752 nm. Subsequently, 100 μL of different concentrations of labeled hydrogel (0, 1, 2, 5, 10, and 50 mg mL -1 ) and 1mL ABTS + The solutions were mixed and placed in a dark oven at 37°C for 6 minutes. Then, the absorbance at 400nm-1000nm was detected using a UV spectrophotometer, and the color changes of solutions of different concentrations after the reaction were recorded using a digital camera. After repeating the experiment three times, the labeled hydrogel was calculated based on the change in absorbance during the experiment. + The scavenging ability of the labeled hydrogel on RNS was evaluated by taking 1,1-diphenyl-2-trinitrophenylhydrazine (DPPH) free radical as a representative of nitrogen free radicals. In the specific operation, 1 mL of DPPH (1 mg dissolved in 24 mL of anhydrous ethanol) solution, 1.5 mL of anhydrous ethanol and 300 μL of labeled hydrogels with different concentrations (0, 1, 2, 5, 10 and 50 mg mL -1 ) were mixed evenly and incubated at 37°C in the dark for 25 min. Subsequently, the absorbance change curve of DPPH was recorded using a UV-visible-near infrared spectrometer, and the DPPH clearance rate was calculated after the experiment was repeated three times in parallel.

[0091] Figure 6 A and 6B show the endoscopy-labeled hydrogels for ABTS + The clearance activity of ABTS + The removal efficiency of ABTS is continuously improved. + The antioxidant activity of the endoscopy-labeled hydrogel was verified by the change of the characteristic absorption peak at 752 nm. The characteristic absorption peak of the reaction system gradually decreased with the introduction of the endoscopy-labeled hydrogel. When the concentration of the endoscopy-labeled hydrogel was 50 g mL -1 The characteristic absorption peak is difficult to detect. Figure 6 C and 6D, the UV absorption curves confirmed that the clearance effect of the endoscopy-labeled hydrogel on RNS was concentration-dependent.

[0092] Embodiment 20

[0093] The blood compatibility of the endoscopic labeled hydrogel was studied. 2 mL of whole blood was centrifuged (5000 rpm, 5 minutes) and rinsed three times with phosphate buffer solution to obtain red blood cells. The obtained red blood cells were stored in 50 mL of phosphate buffer solution for further use. In the hemolysis test, 0.5 mL of the above mouse red blood cells were placed in a 5.0 mL centrifuge tube and incubated with (1) 2.5 mL of phosphate buffer solution (negative control), (2) 2.5 mL of deionized water (positive control) and (3) different concentrations of the labeled hydrogel prepared in Example 1 (1, 2, 5, 10, 50 mg / mL, in 2.5 mL of phosphate buffer solution) in a 37°C water bath for 2 hours. The absorbance of the supernatant at 541 nm (Shimadzu UV-3600 ultraviolet-visible near-infrared spectrometer, Japan) was collected, and the hemolysis rate of the red blood cells was calculated. Figure 7 As shown in A, the calculated hemolysis rates of the labeled hydrogels were all less than 5%. The results showed that the labeled hydrogels had good blood compatibility.

[0094] Embodiment 21

[0095] Fibroblasts were seeded in a 96-well plate and 100 μL of cell culture medium was added for overnight culture. The above culture medium was discarded, and different weights of the endoscopy-labeled hydrogel obtained in Example 1 (1, 2, 5, 10, 50 mg / mL) and 100 μL of new cell culture medium were added. The control group only added 100 μL of cell culture medium (the survival rate was set to 100%). The above cells were placed in a CO2 constant temperature incubator and incubated for 24 hours. CCK-8 and LIVE / DEAD cell activity detection kits were used to quantitatively and qualitatively detect cell survival. Figure 7 As shown in B, the labeled hydrogel does not affect the survival of cells. Similar to the control group, the cells treated with the labeled hydrogel can be stained green by the LIVE / DEAD reagent (live cells are stained green), and almost no cells are stained red (dead cells are stained red) ( Figure 7 C). The results of CCK-8 and LIVE / DEAD cell staining showed that the prepared labeled hydrogels had good cell compatibility.

[0096] Embodiment 22

[0097] The endoscopic marking hydrogel obtained in Example 1 was injected into the stomach and rectum of Kunming rats. Three weeks later, the rats were killed, the marking conditions were observed, and the heart, liver, spleen, lung, and kidney of the Kunming rats were taken for H&E staining. Figure 8 As shown, compared with the control group, the endoscopic labeling hydrogel had no effect on the important organs of the mice, indicating that the endoscopic labeling hydrogel has good in vivo safety.

[0098] Embodiment 23

[0099] Bama pigs were subjected to endoscopic marking surgery of the endoscopic marking hydrogel obtained in Example 1 in the esophagus, stomach and rectum under anesthesia. Ketamine, atropine and azaperidone were injected intramuscularly before anesthesia. Anesthesia was then induced with isoproterenol and maintained with isoflurane. After general anesthesia, the pigs were kept in a lateral position. The injection needle was then inserted at a 45° angle into the submucosal layer of the middle esophagus, the greater curvature of the stomach and the rectum 3 cm from the anus of the three pigs, and 0.5 mL of normal saline was injected into the submucosal layer to raise the mucosa. Subsequently, 0.1 mL of endoscopic marking hydrogel was injected. Endoscopic examinations were performed again on the 15th and 60th days after the injection of the endoscopic marking hydrogel to observe the marking conditions. The pigs were killed after the last endoscopic examination, and the esophageal, stomach and rectal markers were taken for H&E staining.

[0100] like Fig. 9 As shown in A, after the labeled hydrogel was injected into the submucosal layer of the digestive tract through endoscopy, it can be clearly observed that the injection site was black (red arrow). On the 15th day after marking, obvious markings were still observable through endoscopy. 60 days after tattooing, the black color of the mark faded slightly, but we could still find the mark through endoscopy. It is worth noting that in the endoscopic follow-up of the markers, we did not observe any inflammatory changes in the mucosa, which indicates that the use of the endoscopic labeled hydrogel obtained in Example 1 has basically no adverse reactions in the pig digestive tract.

[0101] At the end of the 60-day endoscopic follow-up, the pigs were sacrificed and the marked areas were taken for H&E staining. Fig. 9 As shown in B, 60 days after labeling, black substances were deposited under the mucosa of the esophagus, stomach, and rectum, indicating that 60 days after staining, the endoscopic labeling hydrogel still existed under the mucosa of the labeled site, further proving the stability of PDA / PVP as a dye. It is worth noting that in the H&E results of the stomach, we can observe a small amount of inflammatory cell infiltration around the endoscopic labeling hydrogel, which was not observed in the H&E results of the esophagus and rectum. This may be due to the fact that the adverse reactions of the endoscopic labeling hydrogel in the esophagus and rectum are relatively small, or it may be due to the inflammation caused by the long-term friction of the food stored in the pig stomach at the labeling site.

[0102] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for preparing an endoscopic marking hydrogel, characterized in that: The following steps are involved: The alkaline compound is dissolved in a solvent and stirred to completely dissolve it to obtain a uniform and stable solution; dopamine hydrochloride (DA·HCl) is dissolved in the solution and stirred to completely dissolve it; and then a polymer is added, and after the reaction is complete, an endoscope marking hydrogel is obtained.

2. The method for preparing the endoscopic marking hydrogel according to claim 1, characterized in that: The solvent is any one of distilled water, phosphate buffer solution and physiological saline, the pH of the phosphate buffer solution is 7.4, the w / v concentration of the physiological saline is 0.9%; the concentration of dopamine hydrochloride in the solution is 0.1-10 mol / L; the dissolution temperature of the dopamine hydrochloride is 10-50°C.

3. The method for preparing the endoscopic marking hydrogel according to claim 1, characterized in that: The alkaline compound is any one of sodium bicarbonate, sodium hydroxide, ammonia, potassium hydroxide and lithium hydroxide; the concentration of the alkaline compound is 0.5-5 mol / L; the dissolution temperature of the alkaline compound is 0-30°C.

4. The method for preparing the endoscopic marking hydrogel according to claim 1, characterized in that: The polymer is any one of konjac glucomannan, guar gum and carrageenan; the mass concentration or volume concentration of the polymer in the mixed solution is 1% to 10%.

5. The method for preparing the endoscopic marking hydrogel according to claim 1, characterized in that: The reaction temperature is 0 to 50° C., and the reaction time is 2 to 8 hours.

6. An endoscopic marking hydrogel obtained according to the method described in any one of claims 1 to 5.

7. Use of the endoscopic marking hydrogel as claimed in claim 6 in preparing positioning materials for lesions or specific parts in the gastrointestinal tract.

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