Intragastric balloon

Abstract

The invention relates to the field of medical instruments, and discloses an intragastric balloon which comprises an inner balloon and an outer balloon sleeved outside the inner balloon, and the inner side of the balloon wall of the inner balloon and the inner side of the balloon wall of the outer balloon are respectively provided with a first self-sealing valve and a second self-sealing valve which are located in the same straight line direction; a degradable release valve is arranged on the wall of the inner balloon; a breathable bag is arranged between the inner balloon and the outer balloon, two degradable bags are arranged in the breathable bag, and bicarbonate and citric acid are contained in the two degradable bags respectively; the outer balloon is made of a disulfide bond cross-linked polyester film; the degradation time of the degradable release valve is a, the degradation time of the degradable bag is b, and a is greater than b; the bicarbonate is at least one of sodium bicarbonate and potassium bicarbonate. The intragastric balloon provided by the invention has the characteristics that the size is automatically adjusted, and the mode of being discharged out of a body is convenient and controllable.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and more specifically, to an intragastric balloon. Background Technology

[0002] Currently, intragastric balloon weight loss therapy has two common problems: First, after about three months of balloon placement, patients adapt to the balloon's volume, and weight loss essentially stops; second, when patients experience discomfort, endoscopic intervention is necessary to remove the balloon or adjust its volume. These two points limit the application of intragastric balloons.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] The object of the present invention is to provide an intragastric balloon that aims to improve at least one of the problems mentioned in the background art.

[0005] This invention is implemented as follows: In a first aspect, the present invention provides an intragastric balloon, comprising an inner balloon and an outer balloon sleeved outside the inner balloon, wherein a first self-sealing valve and a second self-sealing valve in the same straight direction are respectively provided on the inner wall of the inner balloon and the inner wall of the outer balloon. The inner balloon is equipped with a biodegradable release valve on its wall; A breathable bag is placed between the inner and outer balloons. Inside the breathable bag are two biodegradable bags, which contain bicarbonate and citric acid, respectively. The external balloon is made of disulfide-crosslinked polyester membrane; The degradation time of the biodegradable release valve is a, and the degradation time of the biodegradable bag is b, where a is greater than b. The bicarbonate is at least one of sodium bicarbonate and potassium bicarbonate.

[0006] In an optional embodiment, the two biodegradable bags are respectively filled with solid bicarbonate and an aqueous solution of citric acid with a mass concentration of 55-65%. Optionally, the ratio of bicarbonate to citric acid aqueous solution is 4g:2.5~3.5mL.

[0007] In an optional implementation, a is 4 to 12 months, and b is 2 to 4 months.

[0008] In an optional embodiment, the disulfide-crosslinked polyester is a disulfide-crosslinked polyvinyl alcohol.

[0009] In an optional embodiment, the biodegradable release valve includes a valve body and a biodegradable rope; The valve body has a channel that connects the inner and outer balloons. The valve body is located on the wall of the inner balloon, and a biodegradable rope is tied to the valve body.

[0010] In an optional embodiment, the inner balloon wall and the valve body are made of the same material, namely polyurethane or silicone. Optionally, the polyurethane hardness is 30A-95A or 40D-70D; Optionally, the silicone hardness is 30A-80A; Optionally, the thickness of the inner balloon wall and / or the valve body wall is 30 μm to 100 μm.

[0011] In an optional embodiment, the inner diameter of the valve body channel is 1~10nn; Optionally, the biodegradable rope is made of one or a mixture of poly(p-dioxanone) and poly(ethylene lactide); Optionally, the LA:GA ratio of the polyethylene glycol is 30~90:10~70.

[0012] In an optional embodiment, the biodegradable bag is made of one or more of polyethylene glycol, polydioxanone, and polyethylene lactide. Optionally, the LA:GA ratio of polyethylene glycol is 50~70:30~50; Optionally, the breathable bag is made of ePTFE breathable membrane.

[0013] In an optional embodiment, the volume of the inner balloon after inflation is 250-750 mL, and the volume of the outer balloon after inflation is 450-1050 mL.

[0014] In an optional embodiment, the method for preparing the disulfide-crosslinked polyester film includes: A mixed solution was obtained by mixing and stirring polyvinyl alcohol solution and 4,4"-dithiodiphenylamine solution evenly, wherein the mass ratio of 4,4"-dithiodiphenylamine to polyvinyl alcohol was 2~50:100. The mixed solution was coated on the surface of the mold, dried, and then heat-treated to obtain a disulfide crosslinked polyester film. Optionally, the polyvinyl alcohol solution is obtained by dissolving polyvinyl alcohol with a degree of alcoholysis of 88%-99% in water to obtain an aqueous solution with a mass concentration of 3% to 15%. Optionally, the 4,4"-dithiodiphenylamine solution is a solution obtained by adding 4,4"-dithiodiphenylamine to a mixed solvent, wherein the mixed solvent includes dimethyl sulfoxide and deionized water in a volume ratio of 1:3~5; Optionally, 4,4"-dithiodiphenylamine is added to a mixed solvent and dissolved by ultrasonication or stirring at 50-60°C to obtain a 4,4"-dithiodiphenylamine solution. Optionally, the mixing and stirring can be carried out at a temperature of 55~65℃ for 1~6 hours; Optionally, the drying method is to dry in a forced-air drying oven at 40-50℃ for 12-24 hours; the heat treatment method is to place the dried film in a vacuum drying oven at 80-100℃ for 1-2 hours.

[0015] The present invention has the following beneficial effects: The gastric balloon provided in this invention can automatically increase in volume after implantation for a period of time, better assisting patients in weight loss. When the patient experiences discomfort or needs to expel the balloon, oral administration of glutathione can cause the balloon to rupture and be expelled through the intestines. This gastric balloon features automatic size adjustment and a convenient and controllable expulsion method. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of the gastric balloon provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the internal structure of the breathable bag.

[0018] Icons: 100-Intragastric balloon; 110-Inner balloon; 111-First self-sealing valve; 112-Degradable release valve; 112a-Valve body; 112b-Degradable cord; 120-Outer balloon; 121-Second self-sealing valve; 130-Ventilating bag; 131-Degradable bag; 132-Bicarbonate; 133-Citrate. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0020] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0021] like Figure 1 and Figure 2As shown, an intragastric balloon 100 provided in this embodiment of the invention includes an inner balloon 110 and an outer balloon 120 sleeved outside the inner balloon 110. A first self-sealing valve 111 and a second self-sealing valve 121 in the same straight direction are respectively provided on the inner wall of the inner balloon 110 and the inner wall of the outer balloon 120. A biodegradable release valve 112 is provided on the wall of the inner balloon 110; A breathable bag 130 is provided between the inner balloon 110 and the outer balloon 120. Two biodegradable bags 131 are provided inside the breathable bag 130. The two biodegradable bags 131 are respectively filled with bicarbonate 132 and citric acid 133. The external balloon 120 is made of disulfide-crosslinked polyester membrane; The degradation time of the biodegradable release valve 112 is a, and the degradation time of the biodegradable bag 131 is b, where a is greater than b. Bicarbonate 132 is at least one of sodium bicarbonate and potassium bicarbonate.

[0022] The gastric balloon 100 provided in this embodiment of the invention is used for weight loss treatment in obese patients, and the method of use is as follows: The injection tube is pre-connected to the inner balloon 110 by passing through the second self-sealing valve 121 and the first self-sealing valve 111 in sequence. The balloon is then implanted into the stomach. Physiological saline is injected into the inner balloon 110 through the injection tube to inflate the inner balloon 110. At this time, the overall volume occupied by the inner balloon 100 in the stomach is V1. The balloon occupies a certain space in the stomach, which is equivalent to reducing the stomach capacity. The patient can feel full after eating a small amount of food, thus achieving weight loss treatment. After time b, once the patient has adapted to volume V1, their weight loss stops or becomes minimal. At this point, the biodegradable bag 131 degrades, and bicarbonate 132 and citric acid 133 react to produce carbon dioxide. The carbon dioxide overflows from the breathable bag 130 and fills the space between the inner balloon 110 and the outer balloon 120, increasing the volume of the gastric balloon 100. After the bicarbonate 132 and citric acid 133 have completely reacted, the overall volume occupied by the gastric balloon 100 in the stomach is V2. The increased proportion of the gastric balloon 100 in the stomach further reduces the stomach capacity, thus better achieving weight loss treatment. For some patients, the increase in balloon volume may cause discomfort. In this case, the patient only needs to take glutathione orally. Glutathione, as a reducing agent, can specifically break disulfide bonds, causing the outermost membrane to degrade and rupture rapidly. The ruptured balloon can then be excreted from the body through the intestines. For some patients who can adapt to the increased balloon volume, after time a, the degradable release valve 112 degrades, and the saline in the inner balloon 110 is released into the outer balloon 120. At this time, the patient takes glutathione orally, which causes the outermost membrane to degrade and rupture rapidly. The ruptured balloon can then be excreted from the body through the intestines.

[0023] The gastric balloon 100 provided by this invention can automatically increase in volume after implantation for a period of time, better assisting patients in weight loss. When the patient experiences discomfort or needs to expel the balloon, oral administration of glutathione can cause the balloon to rupture and be expelled through the intestines. This gastric balloon 100 features automatic size adjustment and a convenient and controllable expulsion method.

[0024] The first self-sealing valve 111 and the second self-sealing valve 121 are existing technologies, and their structures are, for example, composed of two pieces of polyurethane or silicone film to be attached, which will not be described in detail here.

[0025] Optionally, a is 4-12 months, and b is 2-4 months. Experimental studies have shown that patients adapt to the balloon's volume approximately 3 months after implantation in the stomach. Therefore, time b is set to 2-4 months, allowing the biodegradable bag 131 to degrade after the patient adapts, thus increasing the balloon's volume for better weight loss. Depending on the severity of obesity, the treatment time via intragastric balloon implantation is typically 4-12 months; therefore, a is set to 4-12 months.

[0026] Optionally, the volume of the inner balloon 110 after inflation is 250~750 mL, and the volume of the outer balloon 120 after inflation is 450~1050 mL.

[0027] The size of the inner balloon 110 is determined by the solvent in the inner balloon 110 and the amount of physiological saline injected, while the size of the outer balloon 120 is determined by the amount of bicarbonate 132 and citric acid 133 involved in the reaction and the solvent in the outer balloon 120. Therefore, the inflated volumes of the inner balloon 110 and the outer balloon 120 can be adjusted according to actual usage requirements.

[0028] The specific release time can be achieved by selecting biodegradable materials and adjusting their composition.

[0029] Optionally, the biodegradable release valve 112 includes a valve body 112a and a biodegradable rope 112b; The valve body 112a has a channel that connects the inner balloon 110 and the outer balloon 120. The valve body 112a is disposed on the balloon wall of the inner balloon 110, and a biodegradable rope 112b is tied to the valve body 112a. After the biodegradable rope 112b degrades, the channel of the valve body 112a opens, and the saline solution in the inner balloon 110 is released.

[0030] Optionally, the biodegradable rope 112b is made of one or a mixture of poly(p-dioxanone) and poly(ethylene lactide). The choice of one or a mixture of these two materials depends on the required degradation time of the biodegradable rope 112b.

[0031] Optionally, the LA:GA ratio of the polyethylene glycol lactide is 30~90:10~70. Based on the degradation time requirements of biodegradable rope 112b, a polyethylene glycol lactide with a specific molar ratio of the two monomers in the molecular chain within the above range is selected.

[0032] Optionally, the inner balloon 110 and the valve body 112a are made of the same material, namely polyurethane or silicone.

[0033] Optionally, the polyurethane hardness is 30A-95A or 40D-70D; Optionally, the silicone hardness is 30A-80A.

[0034] Choosing polyurethane and silicone within the aforementioned hardness range ensures that the balloon has better mechanical strength and flexibility, avoiding easy rupture and foreign body sensation after implantation in the stomach.

[0035] Optionally, the thickness of the balloon wall of the inner balloon 110 and / or the valve wall of the valve body 112a is 30 μm to 100 μm. This thickness of the balloon wall and valve wall can prevent easy rupture and foreign body sensation after implantation in the stomach.

[0036] Optionally, the inner diameter of the passage in the valve body 112a is 1~10mm.

[0037] The channel of this size ensures that the saline solution in the inner balloon 110 flows into the outer balloon 120 at an appropriate rate.

[0038] Optionally, the biodegradable bag 131 is made of one or more of polyethylene glycol, poly(p-dioxanone), and polyethylene lactide. The choice of one or more of these materials or a mixture thereof depends on the required degradation time of the biodegradable bag 131.

[0039] Optionally, the LA:GA ratio of the polyethylene glycol (PEG) is 50~70:30~50. Based on the required degradation time of the biodegradable bag 131, a PEG with a specific molar ratio of the two monomers in the molecular chain within the above range is selected.

[0040] Optionally, the breathable bag 130 is made of ePTFE (expanded polytetrafluoroethylene) breathable membrane.

[0041] ePTFE breathable membranes are breathable yet waterproof, allowing gases produced by the reaction of bicarbonate 132 and citric acid 133 to escape.

[0042] Optionally, the two biodegradable bags 131 contain solid bicarbonate 132 and an aqueous solution of citric acid 133 with a mass concentration of 55-65%, respectively.

[0043] Optionally, the ratio of aqueous solution of bicarbonate 132 to citric acid 133 is 4g:2.5~3.5mL. Under these dosage and ratio conditions, the amount of carbon dioxide produced by the reaction is about 200~300mL. For example, a 60% (w / w) aqueous solution of citric acid 133 in a ratio of 3mL:4g of potassium bicarbonate can produce 250mL of carbon dioxide gas.

[0044] Optionally, the disulfide-crosslinked polyester is a disulfide-crosslinked polyvinyl alcohol.

[0045] Optionally, the preparation method of the disulfide-crosslinked polyester film includes: A mixed solution was obtained by mixing and stirring polyvinyl alcohol solution and 4,4'-dithiodiphenylamine solution evenly, wherein the mass ratio of 4,4'-dithiodiphenylamine to polyvinyl alcohol was 2~50:100. The mixed solution was coated onto the surface of the mold, dried, and then heat-treated to obtain a disulfide-crosslinked polyester film.

[0046] Specifically, the preparation method of this disulfide-crosslinked polyester film is as follows: Polyvinyl alcohol (PVA) with a degree of alcoholysis of 88% to 99% is dissolved in water to prepare a polyvinyl alcohol solution with a mass concentration of 3% to 15%. Weigh 4,4'-dithiodiphenylamine and add it to a mixed solvent of dimethyl sulfoxide and deionized water (V / V = 1:3~5, for example 1:3, 1:4 or 1:5). Dissolve the solution by sonication or stirring at 50~60℃ to obtain a 4,4'-dithiodiphenylamine solution.

[0047] A polyvinyl alcohol solution and a 4,4'-dithiodiphenylamine solution are stirred at a mass ratio of 4,4'-dithiodiphenylamine to polyvinyl alcohol of 2-50:100 for 1-6 hours at 55-65°C until a homogeneous mixture is obtained. In this step, glycerol plasticizer at a mass ratio of 10%-500% of polyvinyl alcohol may also be selectively added.

[0048] After obtaining the mixed solution, the mixed solution is coated onto the surface of the mold to form a thin film with a thickness of 30~100μm, and dried in a forced-air drying oven at 40~50℃ for 12~24h. After the film is dried, it is then heat-treated in a vacuum drying oven at 80~100℃ for 1~2h to obtain a PVA film containing disulfide bonds.

[0049] In addition to the methods mentioned above, PVA films containing disulfide bonds can also be prepared by other methods such as cystamine dihydrochloride.

[0050] The preparation and assembly method of the entire intragastric balloon 100 is as follows: 1. Valve body preparation Valve body 112a was prepared by negative pressure thermoforming. 2. Preparation of the inner balloon The first self-sealing valve 111 is prepared by hot welding, high-frequency welding or ultrasonic welding; then the first self-sealing valve 111, valve body 112a and inner balloon diaphragm are welded together by the same welding method to form inner balloon 110.

[0051] 3. Preparation of breathable bags A biodegradable material is dissolved in dichloromethane, trichloromethane, or hexafluoroisopropanol to prepare a solution. This solution is then coated to obtain a biodegradable bag 131. The biodegradable bag 131 is filled with a reaction medium and then sealed with the same solvent. Finally, two biodegradable bags 131 are placed inside an ePTFE film and heat-welded to obtain a breathable bag 130.

[0052] 4. Preparation of intragastric balloon First, a second self-sealing valve 121 is prepared by heat welding of a PVA membrane. Then, an inner balloon 110 and a breathable bag 130 are placed in the PVA membrane. Finally, the second self-sealing valve 121 and the PVA membrane are welded together by heat welding to form an outer balloon 120 and the final gastric balloon 100.

[0053] Experimental Example (1) Provide 100 intragastric balloons The valve body 112a of the biodegradable valve has an inner channel diameter of 10nn. The valve body 112a and the inner balloon 110 are made of polyurethane with a hardness of 50A and a thickness of 50μm. The biodegradable rope 112b is made of poly(lactic acid) (LA:GA is 60:40). The expected degradation time is 5 months. The inner balloon 110 has a volume greater than 500mL after full expansion.

[0054] The biodegradable bag 131 is made of lactide (LA:GA ratio 50:50), with an expected degradation time of 5 months. Two biodegradable bags 131 contain 4g of potassium bicarbonate and 3mL of 60% citric acid 133, respectively. A complete reaction will produce approximately 250mL of carbon dioxide gas. Therefore, the inner balloon 110, after full inflation, will have a volume of 750mL.

[0055] The breathable bag 130 is made of ePTFE.

[0056] The external balloon 120 is made of a PVA membrane containing disulfide bonds, with a thickness of 50 μm. The preparation method of the PVA membrane containing disulfide bonds is as follows: Polyvinyl alcohol (PVA) with a degree of alcoholysis of 90% was dissolved in water to prepare a 10% (w / w) polyvinyl alcohol solution. Weigh 4,4'-dithiodiphenylamine and add it to a mixed solvent of dimethyl sulfoxide and deionized water (V / V=1:4). Dissolve the solution by sonication or stirring at 50~60℃ to obtain a 4,4'-dithiodiphenylamine solution.

[0057] A polyvinyl alcohol solution and a 4,4'-dithiodiphenylamine solution were stirred at 60°C for 3 hours at a mass ratio of 30:100 to 30 to obtain a homogeneous mixed solution.

[0058] The mixed solution was coated onto the mold surface to form a 50 μm thick film, which was then dried in a 45°C forced-air drying oven for 20 h. After the film was dried, it was then heat-treated in a 90°C vacuum drying oven for 1 h to obtain a PVA film containing disulfide bonds.

[0059] The first self-sealing valve 111 and the second self-sealing valve 121 are both composed of two polyurethane films with a thickness of 50μm and a hardness of 50A. The two films are attached to each other and the edges of the films are connected.

[0060] (2) Experiment One hundred identical gastric balloons were implanted into the stomachs of three pigs. Physiological saline was injected into each balloon, with V1 being 500 mL and V2 expected to be 750 mL. Starting from day 80, the volume of the gastric balloons was observed every 7 days via gastroscopy to check for any increase in balloon volume, and the number of days on which this increase was observed was recorded. On day 130, the pigs were fed glutathione, and the time it took for the balloons to be expelled after feeding was observed. The results are recorded in Table 1.

[0061] Table 1. Status of the gastric balloon 100 in the pig stomach.

[0062] As can be seen from Table 1, the time for the volume change of the gastric balloon 100 provided by the present invention in the pig's stomach is basically consistent with the expected time. After the expected degradation of the degradable rope 112b, glutathione was fed, and the balloon 110 was expelled within 24 hours. This shows that the actual degradation time of the degradable rope 112b is basically consistent with the expected time, and the balloon can be expelled from the body in a timely manner after feeding glutathione.

[0063] In summary, the gastric balloon 100 provided in this embodiment of the invention can automatically increase in volume after implantation for a period of time, better assisting patients in weight loss. When patients experience discomfort, oral administration of glutathione can cause the balloon to rupture and be expelled from the body through the intestines. This gastric balloon 100 features automatic size adjustment and a convenient and controllable method of expulsion.

[0064] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An intragastric balloon, comprising: The inner balloon and the outer balloon are provided with first and second self-sealing valves on the inner side of the balloon wall of the inner balloon and the inner side of the balloon wall of the outer balloon, respectively, and the first and second self-sealing valves are in the same straight line direction; The balloon wall of the inner balloon is provided with a degradable release valve; The inner balloon and the outer balloon are provided with a gas-permeable bag, and the gas-permeable bag is provided with two degradable bags, and the two degradable bags contain bicarbonate and citric acid, respectively; The material of the outer balloon is a disulfide bond cross-linked polyester film; The degradation time of the degradable release valve is a, and the degradation time of the degradable bag is b, and a is greater than b; The bicarbonate is at least one of sodium bicarbonate and potassium bicarbonate.

2. The intragastric balloon of claim 1, wherein, The two degradable bags contain bicarbonate solid and citric acid aqueous solution with a mass concentration of 55-65%, respectively. Optionally, the ratio of the bicarbonate and the citric acid aqueous solution is 4g:2.5-3.5mL.

3. The intragastric balloon of claim 1, wherein, a is 4-12 months, and b is 2-4 months.

4. The intragastric balloon of claim 1, wherein, The disulfide bond cross-linked polyester is a disulfide bond cross-linked polyvinyl alcohol.

5. The intragastric balloon of claim 1, wherein, The degradable release valve includes a valve body and a degradable rope; The valve body has a channel for connecting the inner balloon and the outer balloon, the valve body is arranged on the balloon wall of the inner balloon, and the degradable rope is tied on the valve body.

6. The intragastric balloon of claim 5, wherein, The material of the balloon wall of the inner balloon and the valve body is the same, which is polyurethane or silica gel; Optionally, the hardness of the polyurethane is 30A-95A or 40D-70D; Optionally, the hardness of the silica gel is 30A-80A; Optionally, the thickness of the balloon wall of the inner balloon and / or the valve wall of the valve body is 30-100μm.

7. The intragastric balloon of claim 5, wherein the balloon is formed of a material that is substantially non-absorbent in the stomach. The inner diameter of the channel of the valve body is 1-10mm; Optionally, the material of the degradable rope is one of poly-p-dioxanone and poly-lactide-co-glycolide or a mixture of the two; Optionally, the LA:GA of the poly-lactide-co-glycolide is 30-90:10-70.

8. The intragastric balloon of claim 5, wherein, The material of the degradable bag is a mixture of one or more of poly-glycolide, poly-p-dioxanone and poly-lactide-co-glycolide; Optionally, the LA:GA of the poly-lactide-co-glycolide is 50-70:30-50; Optionally, the material of the gas-permeable bag is ePTFE gas-permeable film.

9. The intragastric balloon of claim 1, wherein, The volume of the inner balloon after inflation is 250-750mL, and the volume of the outer balloon after inflation is 450-1050mL.

10. The intragastric balloon of claim 1, wherein, The preparation method of the disulfide bond cross-linked polyester film comprises: Mixing and stirring a polyvinyl alcohol solution and a 4,4'-dithiodianiline solution to obtain a mixed solution, wherein the mass ratio of 4,4'-dithiodianiline to the polyvinyl alcohol is 2-50:100; Coating the mixed solution on the surface of a mold, drying and then heat treating to obtain a disulfide bond cross-linked polyester film; Optionally, the polyvinyl alcohol solution is obtained by dissolving polyvinyl alcohol with an alcoholysis degree of 88%-99% in water to obtain an aqueous solution with a mass concentration of 3%-15%; Optionally, the 4,4'-dithiodianiline solution is obtained by adding 4,4'-dithiodianiline to a mixed solvent, and the mixed solvent comprises dimethyl sulfoxide and deionized water in a volume ratio of 1:3-5; Optionally, 4,4'-dithiodianiline is added to the mixed solvent, and is dissolved by ultrasonic or stirring at 50-60°C to obtain the 4,4'-dithiodianiline solution; Optionally, the uniform mixing and stirring manner is stirring at 55-65°C for 1-6h; Optionally, the drying manner is drying in a blast drying oven at 40-50°C for 12-24h, and the heat treatment is heat treating the dried film in a vacuum drying oven at 80-100°C for 1-2h.

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