Degradable drug-loaded hemostatic cotton with double-layer structure

Abstract

The utility model relates to the technical field of medical supplies, in particular to degradable medicine-carrying hemostatic cotton with a double-layer structure, which comprises an internal hemostatic layer and an external functional layer wrapping the hemostatic layer, and the hemostatic layer and the functional layer are respectively formed by freeze-drying same polymer solutions with relatively high mass concentration and relatively low mass concentration. The functional layer is loaded with drugs, the porosity of the hemostatic layer is 60%-80%, and the porosity of the functional layer is 80%-90%. The high-concentration and low-porosity inner hemostatic layer provides mechanical compression force to play a role in rapid hemostasis in the initial stage, the low-concentration and high-porosity outer functional layer can be rapidly degraded, both compression strength and degradation speed are considered and balanced, meanwhile, the outer functional layer is used for loading drugs, and the outer functional layer has the characteristics of high porosity and rapid degradation, so that the effect of rapid hemostasis in the initial stage is achieved. The effect of rapidly releasing the medicine is achieved, it can be ensured that the medicine can be rapidly released to the bleeding part, and wound healing is promoted.

Description

A double-layer biodegradable drug-loaded hemostatic cotton Technical Field

[0001] This utility model relates to the field of medical supplies technology, and in particular to a double-layered biodegradable drug-loaded hemostatic cotton. Background Technology

[0002] Following ear, nose, and throat surgeries (such as sinus surgery and tonsillectomy), hemostasis and infection control are crucial aspects of postoperative recovery. However, existing hemostatic materials and techniques are significantly inadequate in terms of hemostatic efficacy and postoperative treatment, failing to meet clinical needs for highly effective hemostasis and long-lasting therapeutic effects.

[0003] Traditional hemostatic materials (such as gauze, gelatin sponges, and cellulose sponges) are widely used in clinical practice, but their hemostatic effect is limited, and these materials are non-degradable, often requiring secondary removal, which can cause secondary damage and, in severe cases, complications such as infection. Traditional hemostatic materials primarily achieve hemostasis through physical compression or blood absorption, failing to provide sustained and efficient hemostasis. For example, while gelatin sponges have some absorbency, their rapid degradation means they cannot maintain hemostasis for an extended period post-surgery, leading to a higher risk of postoperative bleeding. Gauze and similar materials can achieve hemostasis through compression, but the pressure is uncontrollable, easily causing tissue damage, and may trigger secondary bleeding upon removal. Furthermore, traditional hemostatic materials are mainly used for physical hemostasis and cannot provide adjunctive therapeutic functions such as antibacterial and anti-inflammatory effects. Postoperative infection is a common complication of ENT surgery, and traditional materials cannot effectively prevent or treat infection, leading to prolonged postoperative recovery time and even the need for secondary surgery. For example, after sinus surgery, bacteria easily proliferate in the nasal cavity; traditional hemostatic materials cannot release antibacterial drugs, increasing the risk of postoperative infection. Traditional hemostatic materials only provide hemostasis and cannot simultaneously offer anti-inflammatory or antibacterial therapeutic effects, often leading to complications such as infection and inflammation during postoperative recovery. Some hemostatic materials (such as gauze) need to be removed postoperatively, which not only increases patient discomfort but may also cause secondary bleeding or tissue adhesions. Traditional drug delivery systems (such as microspheres and hydrogels) are typically used independently and cannot be effectively combined with hemostatic materials to achieve the dual functions of hemostasis and treatment.

[0004] Based on this, biodegradable drug-loaded hemostatic cotton has become an indispensable material in the medical field due to its unique advantages. However, there are still many problems to be solved in the current market for biodegradable drug-loaded hemostatic cotton, the most prominent of which is the difficulty in simultaneously achieving degradation rate and compressive strength, resulting in slow drug release. From a materials science perspective, the performance of biodegradable drug-loaded hemostatic cotton mainly depends on its internal microstructure and the characteristics of the polymer materials used. Generally, in order to enhance the compressive strength of the hemostatic cotton and enable it to apply sufficient pressure to the bleeding site for rapid hemostasis, the polymer concentration is usually increased and the porosity of the material is reduced. However, this design significantly slows down the degradation rate of the material because the degradation process depends on the interaction between water molecules and polymer chains and the decomposition by microorganisms in the environment. The dense structure hinders the penetration of water molecules and the contact of microorganisms, making the drug release process extremely slow. The degradation cycle in the human body may take weeks or even months, by which time the wound may have passed the critical period when drug intervention is most needed, resulting in the drug not being able to fully exert its therapeutic effect. In clinical applications, injured patients often need rapid hemostasis and timely drug treatment to prevent infection and promote tissue repair. However, existing hemostatic cotton, due to its slow drug release, cannot provide effective drug protection to the wound in the immediate future, increasing the risk of infection, prolonging the patient's recovery period, and potentially causing serious complications, thus increasing the difficulty of treatment. Furthermore, from a pharmacokinetic perspective, effective drug release needs to match the body's physiological processes. Different drugs have different optimal action windows, which existing biodegradable drug-loaded hemostatic cotton cannot meet. For some antibiotics that require rapid onset of action, if they cannot be rapidly released to the bleeding site in the early stages of wound infection, bacteria may multiply rapidly during this period, developing drug resistance and making subsequent treatment more difficult. Simultaneously, the slow degradation rate may also lead to prolonged drug residue time in the body, increasing the probability of adverse drug reactions and posing a potential threat to the patient's health.

[0005] Furthermore, existing biodegradable drug-loaded hemostatic cotton also has certain limitations during implantation. Due to its lack of good surface properties, it can easily damage tissue when applied to the bleeding site, especially during surgery in sensitive areas, where such damage may lead to serious consequences. Moreover, because the implantation location and wound healing cannot be directly observed, doctors find it difficult to accurately assess the treatment effect during the procedure, which may result in untimely adjustments to the treatment plan and affect the patient's recovery process.

[0006] In summary, existing biodegradable drug-loaded hemostatic cotton has problems in terms of degradation rate, compressive strength, drug release, and implantation safety, which seriously limit its application effect and scope of promotion in clinical treatment. Summary of the Invention

[0007] In view of the above-mentioned defects of the prior art, the technical problem to be solved by this utility model is to provide a double-layer structure biodegradable drug-loaded hemostatic cotton that can achieve a good balance between degradation rate and compression intensity and rapid drug release.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0009] This invention provides a double-layer biodegradable drug-loaded hemostatic cotton, comprising an inner hemostatic layer and an outer functional layer that wraps around the hemostatic layer. The hemostatic layer and the functional layer are formed by freeze-drying the same polymer solution with relatively high and relatively low mass concentrations, respectively. The functional layer is loaded with drug. The porosity of the hemostatic layer is 60%-80%, and the porosity of the functional layer is 80%-90%.

[0010] Preferably, the polymer solution used in the hemostatic layer has a mass concentration of 4%-8%, and the polymer solution used in the functional layer has a mass concentration of 1%-3%.

[0011] Preferably, the compressive modulus of the hemostatic layer is not less than 10 kPa, and the compressive modulus of the functional layer is not greater than 3 kPa.

[0012] Preferably, the degradation cycle of the hemostatic layer is 3-7 days, and the degradation cycle of the functional layer is within 24 hours.

[0013] Preferably, an interface layer with interpenetrating molecular chains of the hemostatic layer and the functional layer is formed between them through an integrated freeze-drying molding process.

[0014] Preferably, the drug loaded in the functional layer is a glucocorticoid, an anti-inflammatory drug, or an antibacterial drug.

[0015] Preferably, the functional layer is loaded with a pH colorimetric agent.

[0016] Preferably, the surface of the functional layer is coated with a lubricant.

[0017] Preferably, the thickness ratio of the functional layer to the hemostatic layer is 1:2 to 1:9.

[0018] Compared with the prior art, this utility model has significant progress:

[0019] This invention relates to a double-layer biodegradable drug-loaded hemostatic cotton, employing a gradient structure design with an inner hemostatic layer of high concentration and low porosity and an outer functional layer of low concentration and high porosity. The high-concentration, low-porosity inner hemostatic layer provides mechanical support and sufficient pressure to achieve effective hemostasis in a short time, playing a role in initial rapid hemostasis. The low-concentration, high-porosity outer functional layer can degrade rapidly, thus achieving a dynamic match of "hemostasis first, degradation later" from the same polymer material. This satisfies both the requirements of high pressure strength (hemostasis requirement) and rapid degradation (avoiding long-term retention), achieving a balance between pressure strength and degradation rate. At the same time, the outer functional layer loads the drug, and its high porosity and rapid degradation characteristics enable rapid drug release, ensuring that the drug can be quickly released to the bleeding site and promote wound healing. Attached Figure Description

[0020] Figure 1 is a schematic diagram of the structure of the double-layer biodegradable drug-loaded hemostatic cotton according to an embodiment of the present invention.

[0021] Figure 2 is a top / front view schematic diagram of the double-layer biodegradable drug-loaded hemostatic cotton shown in Figure 1.

[0022] Figure 3 is a cross-sectional view along direction AA in Figure 2.

[0023] Figure 4 is a cross-sectional view along the BB direction in Figure 2.

[0024] The reference numerals in the attached figures are explained as follows:

[0025] 1. Hemostatic layer

[0026] 2. Functional Layer

[0027] 3 Interface Layer Detailed Implementation

[0028] The specific embodiments of this utility model will be further described in detail below with reference to the accompanying drawings. These embodiments are only used to illustrate this utility model and are not intended to limit it.

[0029] In the description of this utility model, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this utility model. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0030] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0031] Furthermore, in the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0032] Figures 1 to 4 show an embodiment of the double-layer biodegradable drug-loaded hemostatic cotton provided by this utility model.

[0033] This embodiment of a double-layer biodegradable drug-loaded hemostatic cotton includes an inner hemostatic layer 1 and an outer functional layer 2. The functional layer 2 completely encapsulates the hemostatic layer 1, forming an inner and outer double-layer structure where only the functional layer 2 is visible on the outside. The hemostatic layer 1 and the functional layer 2 are formed by freeze-drying the same polymer solution with relatively high and relatively low mass concentrations, respectively. Preferably, the mass concentration of the polymer solution used in the hemostatic layer 1 is 4%-8%, and the mass concentration of the polymer solution used in the functional layer 2 is 1%-3%. The molecular weight of the polymer used in the hemostatic layer 1 is higher than that of the polymer used in the functional layer 2. Both the hemostatic layer 1 and the functional layer 2 are biodegradable, and the functional layer 2 is loaded with a drug. The porosity of the hemostatic layer 1 is 60%-80%, and the porosity of the functional layer 2 is 80%-90%. Preferably, the compressive modulus of the hemostatic layer 1 is not less than 10 kPa, and the compressive modulus of the functional layer 2 is not greater than 3 kPa. Preferably, the degradation cycle of the hemostatic layer 1 is 3-7 days, and the degradation cycle of the functional layer 2 is within 24 hours.

[0034] This embodiment of the biodegradable drug-loaded hemostatic cotton adopts an inner and outer gradient structure design with a high-concentration, low-porosity inner hemostatic layer 1 and a low-concentration, high-porosity outer functional layer 2. The high-concentration, low-porosity inner hemostatic layer 1 provides mechanical support and sufficient pressure to achieve effective hemostasis in a short time, playing a role in initial rapid hemostasis. The low-concentration, high-porosity outer functional layer 2 can degrade rapidly, thus achieving a dynamic match of "hemostasis first, degradation later" with the same polymer material. It simultaneously meets the requirements of high pressure strength (hemostasis requirement) and rapid degradation (avoiding long-term retention), achieving a balance between pressure strength and degradation rate. At the same time, the outer functional layer 2 loads the drug, and its high porosity and rapid degradation characteristics enable rapid drug release, ensuring that the drug can be quickly released to the bleeding site and promote wound healing.

[0035] In this embodiment, the polymers used for the hemostatic layer 1 and the functional layer 2 are preferably polyurethanes, including but not limited to polyester polyurethanes, polyether ester polyurethanes, etc.

[0036] In this embodiment, the drug loaded on functional layer 2 is a glucocorticoid, anti-inflammatory, or antibacterial drug, such as mometasone furoate, budesonide, amoxicillin, cefepime, azithromycin, etc.

[0037] In this embodiment, preferably, an interface layer 3 is formed between the hemostatic layer 1 and the functional layer 2 through an integrated freeze-drying molding process, in which the molecular chains of the hemostatic layer 1 and the functional layer 2 interpenetrate. By using a gradient freeze-drying molding process to form an interpenetrating network of polymer molecular chains of the hemostatic layer 1 and the functional layer 2 in the interface layer 3 region, the peel strength between the hemostatic layer 1 and the functional layer 2 can be increased, effectively preventing detachment between the hemostatic layer 1 and the functional layer 2, and ensuring that the hemostatic layer 1 and the functional layer 2 will not separate during clinical use.

[0038] In this embodiment, preferably, functional layer 2 is loaded with a pH-responsive dye. The pH-responsive dye can be a pH-responsive dye, such as bromophenol blue, phenolphthalein, Congo red, neutral red, or litmus. The pH-responsive dye loaded in functional layer 2 serves to provide real-time feedback on hemostasis status through color changes (e.g., a change from yellow to red when pH increases indicates inflammation), which can intuitively reflect the accuracy of implantation location and the recovery status of the damaged area, enabling visual monitoring and facilitating treatment assessment. The specific binding of the pH-responsive dye to the polyurethane substrate improves the positioning accuracy from 60% to over 95%.

[0039] In this embodiment, preferably, the surface of functional layer 2 is coated with a lubricant. The lubricant can be polyvinylpyrrolidone, polyethylene glycol, sodium hyaluronate, etc. After being modified with the lubricant, the surface of functional layer 2 possesses good lubricity, which helps to adhere to the tissue and reduce frictional damage, thereby reducing tissue damage, improving implantation safety, and demonstrating significant advantages in implantation performance. The coefficient of friction of untreated polyurethane surfaces is as high as 0.3-0.4, which can easily cause mucosal scratches during vascular / gastrointestinal interventions. The lubricant coating can reduce the coefficient of friction to 0.15±0.03.

[0040] In this embodiment, the thickness of functional layer 2 should not be too thick, otherwise it will affect the hemostatic effect. The thickness of functional layer 2 should also not be too thin, otherwise it will not be able to load the drug and pH colorimetric agent. Therefore, preferably, the thickness ratio of functional layer 2 to hemostatic layer 1 is 1:2-1:9.

[0041] The preparation method of the double-layer biodegradable drug-loaded hemostatic cotton in this embodiment includes the following steps.

[0042] Step 1: Prepare the pre-frozen block of hemostatic layer 1: Dissolve a high molecular weight polymer (e.g., polyester urethane with a weight average molecular weight Mw of 100,000 to 110,000) in water or an organic solvent (e.g., dioxane) to prepare a high-concentration (e.g., 4% mass concentration) polymer solution. Pour the solution into a small-sized mold (e.g., a cube or cuboid groove mold) and place it in a freezer or a special freezing device for pre-freezing to obtain the pre-frozen block of hemostatic layer 1.

[0043] Step 2: Preparation of the bottom layer of functional layer 2: Dissolve a low molecular weight polymer (such as polyester polyurethane with a weight average molecular weight Mw of 70,000 to 80,000), a drug (such as mometasone furoate, budesonide, etc.), and a pH colorimetric agent (such as Congo red, bromophenol blue, etc.) in water or an organic solvent to prepare a low concentration (such as 1% by mass) polymer solution, wherein the mass of the drug is 0.2‰ of the polymer mass and the mass of the pH colorimetric agent is 0.5‰ of the polymer mass. Pour the solution into a large-scale mold (such as a cube or cuboid groove mold) and freeze it in a refrigerator freezer or freezing equipment to form the bottom layer of functional layer 2.

[0044] Step 3, Assembly and Secondary Freeze-drying: Place the prepared pre-frozen block of hemostatic layer 1 on top of the bottom layer of functional layer 2 in a large-size mold and center it. Then continue to add the polymer solution from step 2 into the mold until it completely covers the pre-frozen block of hemostatic layer 1. Then put the mold into a freeze dryer and freeze-dry it to obtain a biodegradable hemostatic cotton with inner and outer layers, with the outer functional layer 2 wrapping the inner hemostatic layer 1. Through this integrated freeze-drying molding process, an interface layer 3 is formed between the hemostatic layer 1 and the functional layer 2, where the molecular chains of the hemostatic layer 1 and the functional layer 2 interpenetrate.

[0045] Step 4, Surface Modification: A lubricant (such as polyethylene glycol with a weight-average molecular weight Mw of 300) is sprayed onto the surface of the functional layer 2 of the finished hemostatic cotton to achieve surface modification. This completes the preparation of the bilayer biodegradable drug-loaded hemostatic cotton of this embodiment.

[0046] It should be noted that the drug and pH colorimetric agent can also be added to the surface of functional layer 2 by spraying in step 4, instead of adding them to the polymer solution of functional layer 2 in step 2.

[0047] In a specific embodiment, during a simulated surgical bleeding scenario experiment, the average compressive force applied by traditional hemostatic cotton (using a single polyester polyurethane material, concentration 2.3%, porosity 70% as an example) was 1.2 N / cm. 2 Complete degradation takes 5 days, and the drug release rate is only 30% within 24 hours. In contrast, the bilayer biodegradable drug-loaded hemostatic cotton of this embodiment (hemostatic layer 1 has a 4% PVC concentration and 80% porosity, while functional layer 2 has a 1% PVC concentration and 90% porosity) provides an average of 2.8 N / cm² for hemostatic layer 1. 2 The pressure can achieve effective hemostasis within 3 minutes. The degradation rate of functional layer 2 reaches 60% within 12 hours and is completely degraded within 24 hours. The drug release rate can reach 75% within 24 hours and is close to complete release (98%) within 72 hours, which greatly improves the hemostasis efficiency and the timeliness of drug treatment.

[0048] Taking the treatment of infected wounds as an example, in a simulated wound infection experiment, the control group using traditional hemostatic cotton had a wound bacterial count of 5.2 × 10⁻⁶ after 72 hours. 5 CFU / cm 2 In the experimental group using the bilayer biodegradable drug-loaded hemostatic cotton (functional layer 2 loaded with mometasone furoate) of this embodiment, the number of bacteria in the wound decreased to 1.5 × 10⁻⁶ after 24 hours. 3 CFU / cm 2 After 72 hours, the number of bacteria was almost undetectable (<10). 2 CFU / cm 2 The wound healing time was shortened by 40%-50% compared with the control group, effectively verifying the significant effect of rapid drug release on promoting wound healing.

[0049] In simulated oral surgery experiments, using the bilayer biodegradable drug-loaded hemostatic cotton (functional layer 2 loaded with phenolphthalein chromogenic agent) of this embodiment, doctors can clearly determine whether the hemostatic cotton completely covers the bleeding wound based on the chromogenic area. As the wound heals, the change in the pH value of the wound causes the color of the chromogenic agent to change, gradually fading from the initial red to light pink on the first day after surgery, and becoming almost colorless on the third day. This closely matches the wound healing process, providing doctors with an intuitive and accurate basis for evaluating the treatment effect. Compared with traditional hemostatic cotton, which cannot be monitored in real time, this method has significant advantages.

[0050] Ten experimental rabbits underwent partial hepatectomy. Traditional hemostatic cotton and the biodegradable drug-loaded hemostatic cotton of this embodiment were used, respectively. Postoperative pathological examination showed that the average tissue damage area at the implantation site of the traditional hemostatic cotton was 1.2 cm². 2 The tissue damage was accompanied by obvious tissue tearing and inflammatory reaction; however, in this embodiment, the average tissue damage area at the implantation site of the double-layered biodegradable drug-loaded hemostatic cotton was only 0.3 cm². 2 The tissue morphology is intact with minimal inflammatory cell infiltration, fully demonstrating that it can effectively reduce tissue damage during implantation and improve surgical safety.

[0051] In addition, the double-layer biodegradable drug-loaded hemostatic cotton of this embodiment has the following advantages.

[0052] (1) The product has a simple structure and high functional integration. It adopts an inner and outer double-layer structure design, which is simpler in composition compared to some existing complex multi-layer composite hemostatic cotton structures (such as structures containing 5 or more layers, including hemostatic layer, sustained-release layer, and isolation layer). However, through reasonable material and performance design, it integrates multiple functions such as compression hemostasis, rapid drug release, tissue-friendly implantation, and treatment monitoring. While ensuring comprehensive functionality, it reduces the complexity of product design and production, making it easier for large-scale production and clinical application.

[0053] (2) Flexible and controllable production process, resulting in reduced costs. The addition of drugs and color developers during the preparation process is flexible, allowing for addition either in the polymer solution or in the final spraying step. Companies can adjust this according to actual production needs and cost control. While the freeze-drying process requires precise parameter control, compared to some hemostatic cotton production methods that employ complex processing technologies (such as 3D printing combined with special cross-linking processes), the freeze-drying process has lower equipment requirements and is relatively simpler to operate. Production costs are reduced by 37.5%, resulting in good economic benefits and market competitiveness.

[0054] (3) The material is highly adaptable and has a wide range of applications. In terms of material selection, the hemostatic layer 1 and functional layer 2 can be made from a variety of biodegradable polymers depending on the application scenario and treatment needs. For example, in ophthalmic surgery, a combination of gelatin and polyethylene oxide (PEO) can be used, leveraging the mildness of gelatin and the high lubricity of PEO; in orthopedic surgery, a combination of chitosan and polyvinyl alcohol (PVA) can be used, utilizing the antibacterial properties of chitosan and the high strength of PVA. This flexible selection and combination of materials allows the double-layer biodegradable drug-loaded hemostatic cotton of this embodiment to be widely used in multiple medical fields such as surgery, dentistry, ophthalmology, and orthopedics, meeting diverse clinical needs.

[0055] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present utility model, and these improvements and substitutions should also be considered within the protection scope of the present utility model.

Claims

1. A double-layered biodegradable drug-loaded hemostatic cotton, characterized in that, The product comprises an inner hemostatic layer (1) and an outer functional layer (2) that surrounds the hemostatic layer (1). The hemostatic layer (1) and the functional layer (2) are formed by freeze-drying the same polymer solution with relatively high and relatively low mass concentrations, respectively. The functional layer (2) is loaded with a drug. The porosity of the hemostatic layer (1) is 60%-80%, and the porosity of the functional layer (2) is 80%-90%.

2. The double-layer biodegradable drug-loaded hemostatic cotton according to claim 1, characterized in that, The polymer solution used in the hemostatic layer (1) has a mass concentration of 4%-8%, and the polymer solution used in the functional layer (2) has a mass concentration of 1%-3%.

3. The double-layer biodegradable drug-loaded hemostatic cotton according to claim 1, characterized in that, The compressive modulus of the hemostatic layer (1) is not less than 10 kPa, and the compressive modulus of the functional layer (2) is not greater than 3 kPa.

4. The double-layer biodegradable drug-loaded hemostatic cotton according to claim 1, characterized in that, The degradation cycle of the hemostatic layer (1) is 3-7 days, and the degradation cycle of the functional layer (2) is within 24 hours.

5. The double-layer biodegradable drug-loaded hemostatic cotton according to claim 1, characterized in that, An interface layer (3) is formed between the hemostatic layer (1) and the functional layer (2) through an integrated freeze-drying molding process, in which the molecular chains of the hemostatic layer (1) and the functional layer (2) interpenetrate.

6. The double-layer biodegradable drug-loaded hemostatic cotton according to claim 1, characterized in that, The drug loaded in the functional layer (2) is a glucocorticoid, an anti-inflammatory drug, or an antibacterial drug.

7. The double-layer biodegradable drug-loaded hemostatic cotton according to claim 1, characterized in that, The functional layer (2) is loaded with a pH colorimetric agent.

8. The double-layer biodegradable drug-loaded hemostatic cotton according to claim 1, characterized in that, The surface of the functional layer (2) is coated with a lubricant.

9. The double-layer biodegradable drug-loaded hemostatic cotton according to claim 1, characterized in that, The thickness ratio of the functional layer (2) to the hemostatic layer (1) is 1:2 to 1:9.

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