Hydration-induced shrinkage medical dressing as well as preparation method and application thereof

Abstract

The invention discloses a hydration-induced shrinkage medical dressing and a preparation method and application thereof, the design is ingenious, a hydration-induced shrinkage film is adopted as a composite framework of a driving layer and a polyacrylic acid-N-hydroxysuccinimide ester (PAA-NHS ester) adhesion layer, functional modularization and synergism are achieved, and the application range is wide. The hydration-induced shrinkage medical dressing has excellent mechanical properties, intelligent fluid responsiveness and strong wet tissue adhesion, can intelligently respond to wound exudate and spontaneously generate physical shrinkage, can actively promote wound closure, remarkably improves the wound repair effect, and has a good application prospect. And active mechanical closing of the wound surface is realized without external source energy driving.

Description

Technical Field

[0001] This invention relates to the field of biomedical materials technology, specifically to a hydration-induced contraction medical dressing, its preparation method, and its application. Background Technology

[0002] Wound repair, especially complex wound repair with exudation, swelling or cavities, is a common challenge in clinical practice. Ideal medical dressings not only need to provide a moist healing environment and block microbial invasion, but also need to actively participate in and promote the repair process. At present, traditional dressings such as gauze and foam dressings cannot respond to the dynamic changes of the wound and have the following significant limitations: (1) They cannot actively close the wound: For surgical incisions or lacerations, they can only cover rather than actively reduce the wound area and reduce tissue tension; (2) They lack dynamic adaptability: In the early stage of healing, the wound has edema and a lot of exudate. After the traditional dressing is saturated, it cannot further manage the exudate, resulting in excessive exudate accumulation and soaking the healthy tissue around the wound; in the middle and late stages of healing, the wound shrinks and the volume decreases, and the dressing may form a cavity and lose effective protection; (3) Dressing change is complicated and damaging: The dressing often adheres to the newly formed granulation tissue, and changing it can easily cause secondary damage and patient pain.

[0003] To overcome these shortcomings, existing technologies have developed improved products such as silicone dressings and polyurethane films, focusing on moisturizing and comfort. While their performance has improved, they still lack the ability to actively promote wound closure. In recent years, some stimulus-responsive smart hydrogel dressings have been developed, capable of responding to external stimuli such as temperature, pH, or light. However, these systems often rely on external devices (such as light sources or heat sources) for activation, increasing the complexity, cost, and potential risks of use; or their response conditions are not always stable in the highly variable and dynamically changing wound microenvironment, leading to uncertain clinical efficacy.

[0004] The hydration environment manifested by wound exudate is a persistent and most direct physicochemical characteristic of the healing process. Therefore, developing a dressing that can directly and specifically respond to this natural signal of wound exudate and convert hydration into beneficial mechanical forces (such as contractile force) has become a clear but unresolved urgent need in this field. Thus, there is an urgent need in this field for a novel medical dressing that can intelligently respond to the wound hydration environment, possesses autonomous contractile ability, adheres firmly to moist tissue, has good biocompatibility, and is easy to prepare. Summary of the Invention

[0005] The purpose of this invention is to provide a hydration-induced contraction medical dressing, its preparation method, and its application. This dressing has an ingenious structural design that can intelligently respond to wound exudate and spontaneously generate physical contraction, which can actively promote wound closure and significantly improve the wound repair effect. It solves the problem that existing wound dressings cannot intelligently respond to the wound hydration environment.

[0006] This invention is achieved through the following technical solutions:

[0007] A hydration-induced shrinkage medical dressing comprises a hydration-induced shrinkage film and a polyacrylate-N-hydroxysuccinimide (PAA-NHS ester) adhesive coating fixed to its surface by covalent bonds. The hydration-induced shrinkage film is prepared by immersing a dry film formed of polyvinyl alcohol (PVA) and phytic acid (PA) in a glycerol-water mixed solution to obtain a polyvinyl alcohol / phytic acid / glycerol film, and then activating it by pre-stretching. The polyacrylate-N-hydroxysuccinimide (PAA-NHS ester) adhesive coating is formed by immersing the hydration-induced shrinkage film in a polyacrylate-N-hydroxysuccinimide (PAA-NHS ester) solution and then drying and curing it.

[0008] Preferably, the pre-stretch activation process is as follows: the polyvinyl alcohol / phytic acid / glycerol film is dehydrated at room temperature for 1-24 hours, and then subjected to 1-20 stretching cycles under a constant stress of 5-25 MPa.

[0009] Preferably, the thickness of the hydration-induced shrinkage film is 5 ~ 200 μm, the tensile strength is 17 ~ 40 MPa, and the elongation at break is 200% ~ 900%; it generates initial adhesion within 10 seconds after contact with simulated wound exudate, with an adhesion strength ≥ 90 kPa; and the shrinkage rate is 5% ~ 60% within 2 minutes in a humid environment at 37 ℃.

[0010] The preparation method of the hydration-induced shrinkage film is as follows: polyvinyl alcohol (PVA) and phytic acid (PA) are mixed with water and heated and stirred at 80~95 ℃ to form a uniform casting solution. The solution is cast into a film and dried to obtain a dry film. The dry film is immersed in a glycerol-water mixed solution to obtain a polyvinyl alcohol / phytic acid / glycerol film, which is then pre-stretched and activated to obtain a hydration-induced shrinkage film.

[0011] Preferably, the mass ratio of polyvinyl alcohol (PVA) to phytic acid (PA) is 1-20:1.

[0012] The polyacrylic acid-N-hydroxysuccinimide ester (PAA-NHS ester) solution is prepared by esterification of polyacrylic acid (PAA) with a weight average molecular weight of 100,000~500,000 Da with N-hydroxysuccinimide (NHS). The specific steps are as follows: polyacrylic acid (PAA) is dissolved in sodium 2-mercaptoethanesulfonate (MES) buffer at pH 5.0~6.0, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS) are added, and the carboxyl groups are activated at room temperature. After purification, the polyacrylic acid-N-hydroxysuccinimide ester (PAA-NHS ester) solution is obtained.

[0013] Preferably, the concentration of polyacrylic acid (PAA) is 0.5 ~ 80 mg / mL; the molar ratio of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) to the carboxyl group of polyacrylic acid (PAA) is 0.5 ~ 2, and the molar ratio of NHS to EDC is 1 ~ 2.

[0014] The preparation method of the hydration-induced contraction medical dressing is as follows:

[0015] (1) Preparation of hydration-induced shrinkage film: Polyvinyl alcohol (PVA) and phytic acid (PA) are mixed with water and heated and stirred at 80-95°C to form a uniform casting solution. The solution is cast into a film and dried to obtain a dry film. The dry film is then immersed in a glycerol-water mixed solution with an arbitrary glycerol volume concentration for 1-24 hours to obtain a polyvinyl alcohol / phytic acid / glycerol film. Subsequently, the film is pre-stretched and activated to obtain a hydration-induced shrinkage film.

[0016] (2) Preparation of polyacrylic acid-N-hydroxysuccinimide ester (PAA-NHS ester) solution: Dissolve PAA-NHS ester in MES buffer at pH 5.0 ~ 6.0 to prepare a solution with a concentration of 10 ~ 80 mg / mL;

[0017] (3) Integrated composite dressing: The PAA-NHS ester solution obtained in step (2) is applied to both sides of the hydration-induced shrinkage film obtained in step (1) by spraying, spin coating or soaking, and then dried and cured at room temperature or low temperature vacuum at ≤ 60 ℃ to obtain the hydration-induced shrinkage medical dressing.

[0018] Preferably, the pre-stretch activation process is as follows: the polyvinyl alcohol / phytic acid / glycerol film is dehydrated at room temperature for 1-24 hours, and then subjected to 1-10 stretching cycles under a constant stress of 5-25 MPa.

[0019] This invention relates to a hydration-induced contraction film using PVA and PA as basic components. These components, through a casting and drying process, form a cross-linked network dominated by dynamic hydrogen bonds. The unique feature of this network is its dynamic reversibility: in the dry state, the hydrogen bonds are locked, endowing the film with excellent mechanical properties and storing elastic potential energy. To activate its contraction function, the aforementioned PVA / PA dry film is immersed in a glycerol-water solution to obtain a polyvinyl alcohol / phytic acid / glycerol film. Subsequently, it undergoes a crucial pre-stretching treatment. During this process, glycerol molecules act as plasticizers, embedding themselves into the polymer's dynamic hydrogen bond network. This not only regulates the film's hydrophilicity and flexibility but also lays the foundation for controllable hydration-triggered contraction performance. The hydration triggering mechanism is as follows: when the activated and pre-stretched film comes into contact with wound exudate, water molecules, as a competing component, enter the network, disrupting some of the original hydrogen bonds, causing the film to rapidly swell and soften. Subsequently, with the migration of water, the dynamic hydrogen bond network is reconstructed and restored, thereby generating macroscopic active contraction stress and achieving continuous mechanical traction on the wound edges.

[0020] The PAA-NHS ester bioadhesive coating possesses a dual adhesion mechanism. First, physical adhesion: the long PAA chains provide rapid, initial wet adhesion through segment diffusion, physical entanglement, and hydrogen bonding. Second, covalent anchoring: the highly reactive NHS ester groups can undergo amidation reactions with the free amino groups of wound tissue proteins, forming strong covalent bonds and achieving a durable and stable interfacial bond.

[0021] Furthermore, the hydration-induced shrinkage film of the present invention and the polyacrylic acid-N-hydroxysuccinimide ester (PAA-NHS ester) adhesive coating fixed to its surface by covalent bonds also have temporal and synergistic effects, which is the essence of the present invention.

[0022] The timing sequence is as follows: First step: Interface anchoring. After the hydration-induced contraction medical dressing is applied to the wound, the PAA-NHS ester bioadhesive layer plays its role first, forming a firm and high-strength anchor with the tissue within minutes through both physical and covalent mechanisms. Second step: Hydration triggering and active driving. Wound exudate triggers the hydration-induced contraction film to undergo "hydration-contraction," generating a continuous, inward contractile force.

[0023] Synergistic Effect: This invention achieves its function through a synergistic mechanism of constructing a "dynamic cross-linked network-covalent adhesion interface." The core of this mechanism lies in the formation of a "rigid-reversible" cross-linked network by PVA, PA, and glycerol through high-density dynamic hydrogen bonds. In a dry state, this network is in an energy-locked contractile state; upon contact with water, water molecules competitively break the hydrogen bonds, causing the network to swell and release potential energy. As water migrates, the hydrogen bond network is reconstructed, generating a strong hydration-induced contractile force. Simultaneously, the surface PAA-NHS adhesion layer establishes a strong "bio-anchoring" between the dressing and the wound surface through the physical penetration of PAA chains and the covalent bonding of NHS ester groups with the amino groups of tissue proteins. This design allows the hydration contractile force to be efficiently transferred to the wound edge tissue, actively closing the wound and mimicking and enhancing physiological wound contraction, thereby providing a favorable microenvironment for cell migration and proliferation, and significantly accelerating healing.

[0024] The hydration-induced contraction medical dressing of this invention, upon contact with wound exudate, achieves a firm adhesion with a wet adhesion strength ≥90 kPa through covalent cross-linking of the active ester groups of PAA-NHS with tissue proteins. Simultaneously, the dynamic hydrogen bond network within the film undergoes reconstruction under hydration, resulting in an active contraction rate of 5% to 60%. Through the synergistic mechanism of "covalent adhesion-hydration contraction," this dressing can achieve active mechanical closure of the wound without external energy. Animal experiments show that it significantly promotes wound healing; in a rat full-thickness skin defect model, the wound area reduction rate reached over 65% within 5 days, and the epithelialization rate and collagen deposition were significantly better than the control group.

[0025] The beneficial effects of this invention are as follows:

[0026] 1) Highly intelligent and self-driven: The hydration-induced contraction film directly utilizes the natural biochemical signal of wound exudate as the sole trigger source, converting chemical energy (hydration) into mechanical work (contraction force). No external energy or equipment is required, achieving a truly "on-demand" intelligent response.

[0027] 2) Actively promote healing: Breaking through the passive covering role of traditional dressings, the hydration-induced contraction medical dressing of this invention can actively contract in a moist environment and transmit the contraction force to the wound through a firm interface. By providing continuous and gentle mechanical stimulation, it actively participates in and drives the healing process, which is expected to significantly shorten the healing time and improve the appearance of scars.

[0028] 3) The dressing structure of this invention is ingeniously designed, employing a composite architecture of a hydration-induced shrinkage film as the driving layer and a polyacrylic acid-N-hydroxysuccinimide ester (PAA-NHS ester) adhesion layer. This achieves functional modularity and synergy. The hydration-induced shrinkage medical dressing possesses excellent mechanical properties, intelligent fluid responsiveness, and strong wet tissue adhesion. It can intelligently respond to wound exudate and spontaneously generate physical contraction, actively promoting wound closure and significantly improving wound repair effects. After contacting wound exudate, the hydration-induced shrinkage medical dressing of this invention can covalently cross-link with tissue proteins through the active ester groups of PAA-NHS, achieving a firm adhesion with a wet adhesion strength ≥90 kPa. Simultaneously, the dynamic hydrogen bond network inside the film is reconstructed under hydration, generating an active shrinkage rate of 5% to 60%. Through the synergistic mechanism of "covalent adhesion-hydration shrinkage," this dressing can achieve active mechanical closure of the wound without external energy.

[0029] 4) High biocompatibility and easy to produce: All raw materials have good biocompatibility, and the preparation process is simple and mild, making them very suitable for large-scale industrial production and clinical translation. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the hydration-shrinkage process of the hydration-induced shrinkage film obtained in Embodiment 1 of the present invention, specifically showing the complete dynamic process of the film from the dry pre-stretched state to swelling upon contact with water and then to network reconstruction shrinkage; wherein, (i) initial dry state: showing the polyvinyl alcohol / phytic acid / glycerol film in the pre-stretched state, with an initial length of 4.3 cm and an initial width of 0.3 cm; (ii) hydration shrinkage process: showing the intermediate state of the pre-stretched film shrinking after being immersed in water (e.g., within 2 seconds); (iii) final stable state: showing the stable form reached by the film after hydration shrinkage, with a final length of approximately 1.9 cm and a final width of approximately 0.6 cm.

[0031] Figure 2 This is a comparison of the hydration-induced contraction and closure performance of the dressing of the present invention in an isolated mouse skin wound model in Example 3. (i) An isolated mouse skin wound model with a diameter of 12 cm was prepared; (ii) the dressing was applied to the wound surface; (iii) PBS solution was added to the surface of the dressing to induce a hydration response; (iv) after 30 seconds of triggering the response, the dressing drove the wound area to a stable state of approximately 48% contraction. The initial wound state before dressing application and the wound closure within 1 minute of applying the dressing of the present invention show significant wound edge closure and area reduction.

[0032] Figure 3This is the histological evaluation result of Example 4 applied to a rat full-thickness skin defect model to promote collagen deposition and remodeling in wounds. Masson's trichrome staining was used to show: (i) the blank control group without dressing treatment, (ii) the wound treated with ordinary dressing, and (iii) the bed wound treated with experimental dressing; each group of images includes two time points, day 5 and day 10. Red arrows indicate the wound edge, and blue arrows indicate collagen fibers. Collagen deposition at day 5 post-surgery (left) shows the beginning of new collagen fiber formation (blue); collagen deposition at day 10 post-surgery (right) shows a dense, regularly arranged mature collagen network.

[0033] Figure 4 This is a comparison chart of the shrinkage rates of polyvinyl alcohol-phytic acid films in Example 1 (containing glycerol) and Comparative Example 1 (without glycerol) under hydration conditions. Detailed Implementation

[0034] The following is a further description of the invention, but not a limitation thereof.

[0035] Example 1: Preparation of hydration-induced shrinkage film

[0036] Preparation of casting solution: 30 g of PVA powder (1799, average viscosity-average molecular weight ~77,000, Shanghai Aladdin Biochemical Technology Co., Ltd.) and 30 g of phytic acid (70 wt% in H2O, Shanghai Aladdin Biochemical Technology Co., Ltd.) were slowly added to 60 mL of deionized water. The mixture was mechanically stirred at 300 rpm for 1 hour in an oil bath at 80 ℃ until the PVA was completely dissolved, resulting in a clear and transparent PVA / PA mixed solution.

[0037] Film formation and drying: The casting solution is poured into the substrate film and dried for 24 hours to form a uniform transparent dry film with a thickness of about 50 μm.

[0038] Post-treatment and activation: The obtained PVA / PA dry film was immersed in a deionized aqueous solution containing 70 vol.% glycerol (glycerol-water mixture) for 3 hours to obtain a polyvinyl alcohol / phytic acid / glycerol film. Subsequently, the film underwent pre-stretching activation: dehydration at room temperature for 24 hours, followed by 10 stretching cycles under a constant stress of 25 MPa. During this process, an oriented fibrous structure formed within the film. The final result was a flexible, hydration-responsive shrinkable film. Figure 1 As shown, when the pre-stretched film is immersed in water, it rapidly undergoes driven shrinkage. Video analysis determined that its length shrinkage rate can reach approximately 56% within 2 seconds.

[0039] Example 2: Construction of PAA-NHS ester adhesive coating and integration with composite dressing

[0040] Synthesis of PAA-NHS ester solution: 1 g of PAA (average viscosity-average molecular weight 450,000, Shanghai Aladdin Biochemical Technology Co., Ltd.) was dissolved in 3 mL of MES buffer at pH 5.5 and stirred at room temperature until completely dissolved. Then, 0.5 g of EDC·HCl and 0.25 g of NHS were added sequentially, and the reaction was carried out at 25 ℃ and pH 5.5 (adjusted with 0.1 M HCl) in the dark for 3 hours to obtain the PAA-NHS ester solution.

[0041] Composite dressing integration:

[0042] The hydration-induced shrinkage film obtained in Example 1 was immersed in the above-mentioned PAA-NHS ester solution for 30 minutes, and then dried at 25 °C for 24 hours to form a PAA-NHS ester adhesive coating on both sides of the film, thus obtaining the final composite dressing.

[0043] Example 3: Characterization of Dressing Performance

[0044] Mechanical properties: The mechanical properties of the composite dressing obtained in Example 2 were tested using a universal testing machine according to ASTM D882 standard. The tensile strength was 34.83 MPa, the elongation at break was 210%, and the Young's modulus was 258.42 MPa.

[0045] Wet adhesion strength: The dressing was adhered to a moist pigskin surface using the lap shear method, and its adhesion strength was measured using a universal tensile testing machine. The results showed that the initial wet adhesion strength was 98.33 kPa, and it did not detach even after soaking in PBS for 24 hours, demonstrating the durability of PAA-NHS covalent adhesion.

[0046] Hydration-induced shrinkage rate: Pre-stretched and dried dressings were cut to standard sizes and applied to circular detached mouse skin wounds with a diameter of 12 mm. Phosphate-buffered saline (PBS) was then dropped onto the dressing surface to trigger its hydration response. Dimensional changes in the dressing and the underlying mouse skin were analyzed via video recording. Figure 2 As shown, after hydration is triggered, the dressing actively contracts within 30 seconds, causing the edge of the mouse skin wound to move towards the center, reducing the wound area by approximately 48% (compared to the original wound area).

[0047] Example 4: Verification of in vivo wound closure effect

[0048] To evaluate its healing-promoting effect, an in vivo mouse full-thickness skin defect model experiment was conducted.

[0049] Create a full-thickness skin defect with a diameter of 1.2 cm on fresh mice.

[0050] The dressing of the present invention (experimental group) and the ordinary dressing (control group) were respectively applied to the wound.

[0051] In an environment of 37 ℃ and 80% ~ 90% humidity, the wound area was photographed and recorded at 0 hours, 5 days and 10 days.

[0052] The results showed that the experimental dressing spontaneously contracted upon contact with wound exudate, actively promoting wound closure. By day 5, the wound area reduction rate in the experimental group reached approximately 65%, significantly higher than that in the blank control group (approximately 26%) and the ordinary dressing group (approximately 45%). By day 10, the wounds in the experimental group were almost completely healed, with a closure rate exceeding 96%. Histological analysis further demonstrated (see...) Figure 3 The experimental dressing, through the moderate mechanical force it generates, can accelerate the re-epithelialization of the wound and induce repair cells to arrange themselves in an orderly manner. At the same time, the newly formed epidermal structure of the experimental wound is closer to that of normal skin, accompanied by more orderly and mature collagen deposition and richer angiogenesis.

[0053] Comparative Example 1

[0054] The difference from Example 1 is that the post-treatment activation step of "immersion in a glycerol-water mixture" was omitted. The resulting polyvinyl alcohol / phytic acid film had a hydration shrinkage rate of 10% (see Example 1). Figure 4 Uneven contraction can hinder the smooth closure of the wound.

[0055] Comparative Example 2

[0056] The difference from Example 2 is that an unactivated plain PAA solution (without NHS esters) was used as the adhesive coating. This dressing has some tackiness in the dry state, but its initial adhesion strength on wet pigskin is only 65 kPa, and it completely detaches after soaking in PBS for 10 minutes, failing to provide effective anchoring in a moist wound environment.

[0057] Conclusion: Example 2 and Comparative Example 1 confirm that the present invention can moderately hydrate the PVA / PA dry film by immersing it in a glycerol-water mixed solution, allowing the glycerol to penetrate evenly into the film network, thereby "activating" the film and regulating its hydrophilicity and flexibility. This lays the foundation for achieving controllable hydration-triggered contraction performance and is beneficial for the smooth closure of wounds.

[0058] Example 2 and Comparative Example 2 fully demonstrate that the highly reactive NHS ester groups can undergo amidation reactions with the free amino groups of wound tissue proteins to form strong covalent bonds, achieving a durable and stable interfacial bond.

[0059] The above description is merely a preferred embodiment of the present invention and does not limit its patent scope. Any equivalent structural or procedural transformations made using the content of the present invention's specification and embodiments, whether directly or indirectly applied to other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A hydration-induced shrinkage medical dressing, characterized in that, It consists of a hydration-induced shrinkage film and a polyacrylate-N-hydroxysuccinimide ester adhesive coating fixed to its surface by covalent bonds; the hydration-induced shrinkage film is obtained by immersing a dry film formed of polyvinyl alcohol and phytic acid in a glycerol-water mixed solution to obtain a polyvinyl alcohol / phytic acid / glycerol film, and then activating it by pre-stretching; the polyacrylate-N-hydroxysuccinimide ester adhesive coating is formed by immersing the hydration-induced shrinkage film in a polyacrylate-N-hydroxysuccinimide ester solution and then drying and curing it.

2. The hydration-induced shrinkage medical dressing according to claim 1, characterized in that, The specific operation for pre-stretching activation is as follows: the polyvinyl alcohol / phytic acid / glycerol film is dehydrated at room temperature for 1-24 hours, and then subjected to 1-20 stretching cycles under a constant stress of 5-25 MPa.

3. The hydration-induced shrinkage medical dressing according to claim 1, characterized in that, The hydration-induced shrinkage film has a thickness of 5 ~ 200 μm, a tensile strength of 17 ~ 40 MPa, and an elongation at break of 200% ~ 900%; it generates initial adhesion within 10 seconds after contact with simulated wound exudate, with an adhesion strength ≥ 90 kPa; and its shrinkage rate is 5% ~ 60% within 2 minutes in a humid environment at 37 ℃.

4. The hydration-induced shrinkage medical dressing according to claim 1, characterized in that, The preparation method of hydration-induced shrinkage film is as follows: Polyvinyl alcohol, phytic acid and water are mixed and heated and stirred at 80~95℃ to form a uniform casting solution, which is then cast into a film and dried to obtain a dry film; the dry film is immersed in a glycerol-water mixed solution to obtain a polyvinyl alcohol / phytic acid / glycerol film, which is then pre-stretched and activated to obtain a hydration-induced shrinkage film.

5. The hydration-induced shrinkage medical dressing according to claim 4, characterized in that, The mass ratio of polyvinyl alcohol to phytic acid is 1-20:

1.

6. The hydration-induced shrinkage medical dressing according to claim 1, characterized in that, The polyacrylic acid–N-hydroxysuccinimide ester solution is prepared by esterification of polyacrylic acid with a weight average molecular weight of 100,000 to 500,000 Da with N-hydroxysuccinimide. The specific steps are as follows: polyacrylic acid is dissolved in sodium 2-mercaptoethanesulfonate buffer at pH 5.0 to 6.0, and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide are added for carboxyl activation at room temperature. After purification, the polyacrylic acid–N-hydroxysuccinimide ester solution is obtained.

7. The hydration-induced shrinkage medical dressing according to claim 6, characterized in that, The concentration of polyacrylic acid is 0.5~80 mg / mL; the molar ratio of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide to polyacrylic acid carboxyl group is 0.5~2, and the molar ratio of NHS to EDC is 1~2.

8. The method for preparing the hydration-induced contraction medical dressing according to claim 1, characterized in that, The steps are as follows: (1) Preparation of hydration-induced shrinkage film: Polyvinyl alcohol, phytic acid and water are mixed and heated and stirred at 80 ~ 95 ℃ to form a uniform casting solution, which is then cast into a film and dried to obtain a dry film; the dry film is immersed in a glycerol-water mixed solution with an arbitrary glycerol volume concentration for 1-24 hours to obtain a polyvinyl alcohol / phytic acid / glycerol film, which is then pre-stretched and activated to obtain a hydration-induced shrinkage film; (2) Preparation of polyacrylic acid-N-hydroxysuccinimide ester solution: Dissolve PAA-NHS ester in MES buffer at pH 5.0 ~ 6.0 to prepare a solution with a concentration of 10 ~ 80 mg / mL; (3) Integrated composite dressing: The PAA-NHS ester solution obtained in step (2) is applied to both sides of the hydration-induced shrinkage film obtained in step (1) by spraying, spin coating or immersion, and then dried and cured at room temperature or low temperature vacuum at ≤ 60 ℃ to obtain the hydration-induced shrinkage medical dressing.

9. The preparation method according to claim 8, characterized in that, The mass ratio of polyvinyl alcohol to phytic acid is 1-20:

1.

10. The preparation method according to claim 8, characterized in that, The specific operation for pre-stretching activation is as follows: the polyvinyl alcohol / phytic acid / glycerol film is dehydrated at room temperature for 1-24 hours, and then subjected to 1-20 stretching cycles under a constant stress of 5-25 MPa.

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