Hydrogel capable of responding to ROS (reactive oxygen species), controlling drug release and having high tensile strength and high viscosity as well as preparation method and application of hydrogel

Abstract

The invention relates to the technical field of biological materials and medical products, in particular to active oxygen responding and removing water-release hydrogel as well as a preparation method and application thereof. The nicotinamide prodrug in the hydrogel developed by the invention serves as a non-covalent cross-linking agent, free radical polymerization provides a hydrogel skeleton, and the hydrogel has the characteristic of flexibly changing the physical properties of the gel, so that the hydrogel has multiple purposes, and the proved purposes include cutting wounds, wound surfaces and other scenes with sharp active oxygen level increase. Compared with a traditional material, the material has the advantages of flexible physical shape change ability, strong adhesion and excellent stretching ability, and has significant advantages in application in irregular wound scenes.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of biomaterials and medical products, in particular to a ROS-responsive controllable drug release hydrogel with high stretchability and high adhesion, a preparation method and applications thereof. BACKGROUND

[0002] The information disclosed in this Background section is only for the purpose of increasing the understanding of the general background of the application and does not necessarily constitute an admission or a recognition that the information forms part of the prior art that is already known in any country in the world.

[0003] Wounds refer to the damage of skin or mucosa integrity caused by trauma, infection, surgery or chronic diseases, which may involve subcutaneous tissue or even deep structures. Clinically, the damage of skin barrier is considered to increase the risk of pathogen invasion, leading to local infection or systemic sepsis. In addition, wound pain and scar contracture can cause dysfunction, such as limited joint movement. Chronic wounds can consume nutrients and increase metabolic burden, and even induce osteomyelitis or systemic inflammation.

[0004] The field of skin wound repair has long been faced with core challenges such as insufficient mechanical properties of traditional dressings, weak environmental responsiveness and uncontrollable drug release. Although hydrogels have advantages over traditional dressings in avoiding secondary damage caused by drying, high water absorption to maintain wound moisture and accelerate healing, and adding functional components to endow hydrogels with specific properties, existing hydrogel materials have physical performance defects such as rigid network structure that is difficult to adapt to skin dynamic activities (such as joint bending and muscle stretching), low elastic modulus, easy breakage and poor adhesion. In addition, the single function and lack of active response to pathological signals in the wound microenvironment also make the drug release out of sync with the healing process, which is a problem in the use of hydrogels in tissue repair. Therefore, hydrogels with high adhesion and high stretchability that can firmly adhere to damaged tissues to adapt to tissue dynamic activities and respond to pathological signals for intelligent drug release have become an important research direction in the repair of damaged tissues. Triggered stimulus-responsive hydrogels can provide targeted drug release as needed, making them have great application potential for intelligent improvement of treatment effect and promotion of personalized medicine. Phenylboronic ester bond is a suitable cross-linking bond for hydrogels, which is a reversible reaction between phenylboronic acid and cis-diol. When applied in hydrogels, it can endow the hydrogels with dynamic reversible cross-linked network, ROS responsiveness and intelligent drug release capacity, making them play multiple roles in wound healing: high adhesion provided by phenylboronic ester can make it easier to combine with the skin, closely adhere to irregular wounds through self-repairing properties and reduce mechanical damage; dynamically release drugs in response to wound ROS microenvironment (such as infection or inflammation state) to synergistically inhibit infection, scavenge reactive oxygen species and promote skin recovery; its biomimetic flexible structure supports tissue remodeling, and the degradation products have good biocompatibility.

[0005] The nucleophilic substitution reaction between the pyridine ring in nicotinamide and 4-bromomethylphenylboronic acid can respond to reactive oxygen species (ROS). Furthermore, protonation of the pyridine can provide a non-covalent crosslinking agent for hydrogels through positive and negative charge linkages, significantly improving hydrogel extensibility. When this bond is applied in the hydrogel to respond to ROS, its cleavage and drug release can dynamically respond to the reactive oxygen species microenvironment.

[0006] In the initial stage of skin trauma (24-72 hours), neutrophil and macrophage infiltration leads to a surge in local ROS concentration, providing a specific trigger signal for intelligent drug release. By embedding a ROS-sensitive nicotinamide prodrug into a hydrogel network, ROS concentration-dependent controlled drug release can be achieved: maintaining structural stability in normal tissues, while dynamically breaking bonds in inflamed areas to directionally release nicotinamide. Compared to traditional enzyme-responsive systems, the ROS-sensitive mechanism does not depend on specific enzyme expression levels and can precisely match the ROS concentration gradient of different trauma types (acute lacerations, chronic ulcers), thereby optimizing the synchronization of drug release kinetics and repair processes.

[0007] With the rapid rise of minimally invasive surgery, the clinical demand for multi-purpose and easy-to-use hydrogel functional dressings has become particularly urgent. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a hydrogel material and its preparation method that can respond to and scavenge reactive oxygen species while simultaneously releasing drugs. The material is based on a copolymer of polyvinyl alcohol, acrylamide, and 2-acrylamido-2-methylpropanesulfonic acid. Nicotinamide prodrugs form crosslinking points with polyvinyl alcohol and covalent crosslinking chains through the formation of phenylboronic acid ester bonds and positive and negative charge linkages, respectively, to form the hydrogel. This hydrogel possesses advantages such as strong adhesion, ultra-high tensile strength, and good biocompatibility. Combining these properties, the material is suitable for wound healing. The core design of this hydrogel lies in resolving multiple contradictions in skin adhesion scenarios through the synergistic optimization of a dynamic crosslinking network and a biomimetic adhesion mechanism.

[0009] The technical solution adopted in this invention is as follows: In a first aspect of the invention, a hydrogel with ROS-responsive controlled-release drug and high tensile strength and viscosity is provided, which uses nicotinamide prodrug (NP) as a non-covalent crosslinking agent to bridge polyvinyl alcohol (PVA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS); on this basis, a covalent crosslinking network is formed by thermally initiated copolymerization reaction of AMPS and acrylamide (AM), thereby constructing a stable bi-crosslinked hydrogel framework.

[0010] This invention employs a biomimetic dual-network structure design: 1) a rigid framework composed of covalently cross-linked polyacrylamide, providing initial mechanical support; 2) a flexible energy dissipation layer composed of dynamic non-covalent interactions (phenylboronic acid ester bonds, positive and negative charge connections), which absorbs deformation energy through reversible bond breakage, endowing the material with tear resistance, rapid rebound capability, and self-healing ability, significantly extending the service life of the material in dynamic wounds.

[0011] In a second aspect of the invention, a method for preparing the ROS-responsive, controlled-release hydrogel with high tensile strength and high viscosity is provided, the method comprising the following steps: S1. Dissolve 2-acrylamido-2-methylpropanesulfonic acid (AMPS) in water until fully dissolved; S2. Neutralize the solution obtained in step S1 to maintain its pH value at a slightly alkaline level; S3. Add polyvinyl alcohol (PVA) and acrylamide (AM) to the solution obtained in step S2, heat and stir until completely dissolved; S4. Add the nicotinamide prodrug (NP) to the solution obtained in step S3 and stir to dissolve; wherein, the NP structure is as follows: ; S5. Dissolve N,N'-methylenebisacrylamide (MBA) and 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide] in water until fully dissolved; S6. Add the solution obtained in step S5 to the solution in step S4 according to the set ratio, and mix well. S7. Nitrogen gas is introduced into the mixed solution prepared in step S6 to remove oxygen, and then a thermally initiated polymerization reaction is carried out to form a double crosslinked hydrogel.

[0012] Furthermore, the mass concentration of AMPS in the solution obtained in S1 is 3-8%, preferably 5%.

[0013] Furthermore, the weakly alkaline environment in S2 is to provide suitable reaction conditions for the phenylboronic ester bond, and its alkaline pH is generally controlled at around 8 (7.5~8.5).

[0014] Furthermore, the mass concentration of PVA and AM in the solution obtained from S3 is 5-15%.

[0015] In S4, the NP is prior art, readily available to those skilled in the art. For example, It can be prepared using the method described in CN120504685A.

[0016] Furthermore, the mass concentration of nicotinamide prodrug in the solution obtained in S4 is 0%~25%, excluding 0%, and the physical properties of the gel can be dynamically changed by changing the amount of prodrug according to different application scenarios.

[0017] In S4, (1) Nicotinamide prodrugs, as drug selection, not only have certain efficacy of nicotinamide itself, but also have advantages in synthesis such as low raw material price and high synthesis yield. (2) As the drug carrier of hydrogels, nicotinamide prodrugs have medicinal functions and also have the structural function of gelation: 1) The phenylboronic acid ester bond of nicotinamide prodrugs can be linked with polyvinyl alcohol. 2) The protonated pyridine of nicotinamide prodrugs can be linked with negatively charged polyradical long chains. Based on this, cross-linking sites can be formed between the two long chains. (3) Since both cross-linking sites have ROS response characteristics, the cross-linking sites can provide the gel with the characteristic of responding to and clearing ROS after gelation. (4) Both cross-linking methods are non-covalent cross-linking, which can bring high adhesion and high tensile properties to the gel. In addition to the effect of the drug itself, the treatment of wounds mainly utilizes the physical effect of hydrogel materials. On the one hand, the wound is glued together without sutures, and on the other hand, infection is prevented. The drug also plays an antioxidant and antibacterial role.

[0018] Further, the mass concentration of MBA in the solution obtained in S6 is 0.03~0.08%, preferably 0.05%; the mass concentration of 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide] is 0.05~0.15%, preferably 0.1%.

[0019] Furthermore, in S7, the polymerization reaction time is 10~15h, preferably 12h; the reaction temperature is 90~95℃.

[0020] In a third aspect of the invention, the use of the ROS-responsive, controlled-release hydrogel with high tensile strength and high viscosity in the preparation of a medicament or dressing for repairing cuts, abrasions, or various types of wounds is provided.

[0021] Furthermore, the wound is a linear wound repair and / or a facial wound repair.

[0022] Compared with the related technologies known to the inventors, one of the technical solutions of the present invention has the following beneficial effects: (1) The advantages of this invention are that the preparation process is simple, all raw materials are commercially available, the required synthetic monomers have high yields and are easy to purify, and the hydrogel materials are easy to prepare on a large scale and promote in the market.

[0023] (2) The ROS-responsive hydrogel provided by this invention has a wide range of applications. After gelation, the hydrogel exhibits strong universal adhesion and excellent extensibility, and different viscoelasticities can be imparted to the hydrogel depending on the amount of raw materials, making it suitable for various application scenarios. Proven implementation examples include: 1) wound adhesives, which can replace medical sutures to close wounds and promote healing; 2) surface-type wound dressings, which serve as multifunctional dressings to cover and heal wounds. This invention is particularly suitable for daily use and has significant value and importance for emergency treatment of everyday accidental injuries.

[0024] (3) The polyvinyl alcohol used in this invention is a pharmaceutical excipient approved by the U.S. Food and Drug Administration (FDA), which has low biotoxicity, good biocompatibility, and is safe to use. At the same time, due to the medicinal value of nicotinamide itself, it can also play a role in improving function after wound repair. Attached Figure Description

[0025] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0026] Figure 1 Schematic diagram of a hydrogel that can respond to and remove reactive oxygen species and release drugs. (A) Chemical molecular structure of each component of the hydrogel; (B) Macroscopic view of the hydrogel before and after gelation; (C) Microscopic view of the hydrogel after gelation; (D) Rheological properties of each component of the hydrogel.

[0027] Figure 2 : Schematic diagram of the gelation mechanism of drug-releasing hydrogel that can respond to and eliminate reactive oxygen species. (A) Comparison of prodrug and prodrug reacting with polyvinyl alcohol 1H NMR spectrum; (B) Infrared spectrum of each component of hydrogel and after gelation; (C) Stretching properties of hydrogel in salt environments of different concentrations; (D) Verification of hydrogel synthesis strategy by precipitation of positive and negative charge polymers.

[0028] Figure 3 Effects of prodrugs as non-covalent crosslinking agents and covalent crosslinking agents on the swelling rate of hydrogels (A) Effects of prodrug grouping on the swelling rate of hydrogels (B) Effects of covalent crosslinking agent grouping on the swelling rate of hydrogels

[0029] Figure 4 Mechanical properties of each group of the hydrogel that can respond to and eliminate reactive oxygen species. (A) Tensile stress and strain of the hydrogel prodrug group; (B) Tensile stress and strain of the hydrogel covalent crosslinker group; (C) Compressive stress and strain of the hydrogel prodrug group.

[0030] Figure 5 Adhesive properties of hydrogels that can respond to and remove reactive oxygen species. (A) Macroscopic diagram of adhesive properties; (B) Shear adhesion force of prodrug groups.

[0031] Figure 6 : Self-healing properties of hydrogels that can respond to and eliminate reactive oxygen species. (A) Macroscopic diagram of hydrogel self-healing; (B) Cyclic strain analysis in rheology; (C) Microscopic self-healing of hydrogels.

[0032] Figure 7 : Reactive oxygen species (ROS) response and drug release of a hydrogel capable of responding to and eliminating ROS. (A) Molecular formula of prodrug decomposition in response to ROS; (B) 1H NMR detection of prodrug after ROS response; (C) Zeta potential of prodrug before and after ROS response; (D) Zeta potential of prodrug and polyvinyl alcohol solution before and after ROS response; (E) UV spectrum of prodrug hydrogel response to ROS over time; (F) High performance liquid chromatography of prodrug hydrogel response to ROS over time.

[0033] Figure 8 : The reactive oxygen species scavenging ability of the drug-releasing hydrogel that can respond to and scavenge reactive oxygen species. (A) ABTS antioxidant capacity of the hydrogel prodrug group; (B) Fluorescence spectrum of the hydrogel prodrug group after co-culturing with H2O2.

[0034] Figure 9 Biocompatibility of hydrogels that can respond to and eliminate reactive oxygen species. (A) Compatibility of the hydrogel prodrug group with L929 cells; (B) Hemolysis level of the hydrogel prodrug group.

[0035] Figure 10 Application of tissue adhesives in hydrogels that can respond to and remove reactive oxygen species. (A) Macroscopic view of hydrogel repair of linear wounds; (B) Femtosecond laser detection of skin samples after hydrogel repair of linear wounds; (C) HE staining and Masson staining after hydrogel repair of linear wounds.

[0036] Figure 11 Application of hydrogels that can respond to and remove reactive oxygen species in wound repair. (A) Macroscopic view of wound repair by hydrogels; (B) Schematic diagram of wound repair by hydrogels; (C) Healing rate of wound repair over time; (D) HE staining and Masson staining after repair of a linear wound by hydrogels. Detailed Implementation

[0037] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0038] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, and / or combinations thereof.

[0039] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0040] First, a detailed description of the main raw materials and experimental equipment required for this invention will be provided.

[0041] Experimental apparatus: electronic balance, ultrasonic mixer, magnetic stirrer, pH meter, oil bath, water purification system, pipette, nitrogen device.

[0042] Experimental drugs: Nicotinamide, 2,2'-azobis(2-methyl-N-(2-hydroxyethyl)propionamide), and polyvinyl alcohol (PVA, degree of hydrolysis: 98.0-99.0 mol%, viscosity: 5.2-6.0 mPa·s) were purchased from Aladdin Company. Acrylamide (AM), N,N'-methylenebisacrylamide (MBA), 4-(bromomethyl)phenylboronic acid, and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) were all purchased from Energi Company. Sodium hydroxide was supplied by SCR Company. The nicotinamide prodrug (NP) was prepared according to the method in Example 1 of CN120504685A.

[0043] Example 1: Preparation of a hydrogel capable of responding to and scavenging reactive oxygen species to release drugs The target product was obtained by crosslinking polyvinyl alcohol and AM and AMPS copolymers using nicotinamide prodrug as a crosslinking agent (see schematic diagram for specific chemical structure). Figure 1 A). Includes the following steps: S1. Prepare a 50 mg / 950 μL AMPS solution; S2. Neutralize the solution to pH 8 using NaOH; S3. Weigh 100 mg PVA and 100 mg AM into a 5 mL vial, add 950 μL AMPS solution, stir at 80 °C to dissolve the two substances, and homogenize. S4. After homogenization, weigh out 0, 5, 10, 15, 20, and 25 mg of nicotinamide prodrug, respectively, and add them to the 950 μL solution obtained in S3. Stir until clear. The products are named NPH0, NPH5, NPH10, NPH15, NPH20, and NPH25 according to the amount of prodrug.

[0044] S5. Prepare a small solution containing 1 mg MBA / 100 μL and 2.2 mg 2,2'-azobis(2-methyl-N-(2-hydroxyethyl)propionamide) / 100 μL; S6. Take 40 μL of the solution obtained in S6, add it to the solution obtained in S4, stir and purge with nitrogen to remove air, react overnight at 90°C to obtain NPH ( Figure 1 B Figure 1 C). In rheology, the storage modulus and loss modulus of NPH are tested ( Figure 1 (D) shows that as the amount of NP gradually increases, the storage modulus of NPH gradually approaches the loss modulus, and the gel tends to be more liquid. This is because NP, as a non-covalent crosslinking agent, causes the gel to gradually lose the covalent crosslinking rigidity of free radical polymerization.

[0045] Example 2: Exploring the Principle of Hydrogels that Can Respond to and Eliminate Reactive Oxygen Release Drugs The successful synthesis of NPH was demonstrated by separately verifying the formation of phenylboronic esters and the linking of positive and negative charges (see [link to NPH synthesis]). Figure 2 ), and NP and NP with PVA were analyzed under weakly alkaline conditions using 1H NMR spectra to verify the successful formation of phenylboronic ester bonds. Figure 2 A). The results indicate that the shift of the H peak at a specific position is due to the strong electron-withdrawing inductive effect of the alkoxy group caused by the formation of the phenylboronic ester bond, which directly reduces the electron cloud density of the benzene ring, causing the hydrogen atoms on the benzene ring and the linking group to shift to a higher field. This proves that phenylboronic ester bonds already exist in the system at room temperature. (In the FTIR spectrum...) Figure 2 In B), the BO bond in NP appears at 1388 cm⁻¹, while in the prodrug gel, it appears at 1308 cm⁻¹. This is due to the increased coordination number and bond length of the BO bond, leading to the formation of phenylboronic ester bonds and a decrease in vibrational frequency, resulting in a redshift. This also proves the successful connection of phenylboronic ester bonds in the prodrug hydrogel. Before gelation, NPH15 was treated with gradient concentrations of NaCl, with additional salt solutions of 0, 200, 400, and 600 mM. Tensile stress-strain tests were then conducted. The results showed that the tensile properties of the hydrogel weakened with increasing salt concentration. This is because the increase in salt concentration introduces a large number of positive and negative Na₂O₃ electrons. + and Cl -The original pyridine protonated and sulfonic acid anion groups were seized, reducing the number of non-covalent positive and negative charge links, thus decreasing the gel's ability to dissipate external forces and reducing its stretchability. When positively charged polymer chains meet negatively charged long chains, uneven aggregation and sedimentation occur. Based on this, when AMPS and AM were polymerized into a negatively charged long-chain precursor solution, and PVA was dissolved in it, a white flocculent sedimentation occurred when a high-concentration NP solution was added. This was attributed to the rapid connection of the two through phenylboronic ester bonds when NP with a protonated pyridine structure was added to a solution containing PVA, forming a positively charged long-chain structure. When the two long-chain structures were mixed, their uneven aggregation manifested as a white flocculent phenomenon. Figure 2 D), confirming that the positive and negative charges in the system are successfully linked.

[0046] Example 3: Mechanical property testing of hydrogels capable of responding to and scavenging reactive oxygen species for drug release. In the swelling properties of hydrogels ( Figure 3 In the study, when the amount of NP increased from 0 to 5 mg, 15 mg, and 25 mg, the swelling ratio of the gel increased from 384.2% to 462.4%, 516.5%, and 541.8%, respectively. However, when the amount of MBA changed from 1 to 2, 3, and 4, the swelling ratio of the hydrogel decreased from 602.2% to 440.0%, 402.8%, and 365.5%, respectively. This demonstrates that while the non-covalent crosslinking agent NP introduces a dissipation mechanism to the gel, it can also loosen the gel network. However, the introduction of MBA can strengthen covalent crosslinking and dynamically adjust the physical properties of the hydrogel. In the gel stress-strain experiment (… Figure 4 With increasing NP content, the elongation of the hydrogel increased from 251% at 0 mg NP to 305% (5 mg), 871% (15 mg), and 1652% (25 mg). This is mainly because when the hydrogel is stretched, the non-covalent crosslinks preferentially break as sacrificial bonds, absorbing external energy and dissipating it as heat, thus avoiding stress concentration and fracture in localized areas. However, the weak bond forces of non-covalent bonds will macroscopically reduce the strength of the hydrogel. Figure 4 C) As the NP concentration increases, the slope of the compressive stress-strain curve decreases, indicating a reduction in the Young's modulus of the gel. To enhance the gel's strength for applications in various scenarios, the covalent crosslinking agent MBA is introduced to strengthen the covalent crosslinking network. Figure 4 B) As the amount of MBA used increases, the gel shows a trend of gradually hardening but becoming brittle.

[0047] Example 4: Adhesion performance test of hydrogel capable of responding to and removing reactive oxygen species. Phenylboronic acid ester bonds themselves possess good adhesive properties. Through bireversible crosslinking, the hydrogel can better conform to the surface microstructure upon contact, increasing the effective contact area and strengthening interfacial interactions by adjusting the local structure, such as the breaking and recombination of dynamic bonds. Shear adhesion ( Figure 5 In section B), as the amount of NP increases, the shear adhesion force of the material gradually increases. When NP equals 20 mg, the shear stress reaches 295 kPa, but decreases to 276 kPa when the content is 25 mg. This phenomenon is due to the lower gel strength at high NP levels, causing the gel itself to break down before reaching maximum adhesion force. When testing the adhesion of NPH to various objects (…),… Figure 5 A), NPH also exhibits broad adhesion properties on various materials.

[0048] Example 5: Self-healing properties of hydrogels capable of responding to and eliminating reactive oxygen species releasing drugs Different repair phenomena occurred after different batches of gels were joined. Figure 6 A) is due to the non-covalent and reversible nature of the connections between positive and negative charges and the phenylboronic acid ester bonds, which can re-link after being broken, manifesting as macroscopic gel self-repair. In rheological analysis ( Figure 6 (B) It can be seen that the gel breaks down in the high-strain region where G' is less than G'', but when it transitions to low strain where G' is greater than G'', it undergoes repair. Under a microscopic scale, the gel is scratched with a scalpel ( Figure 6 C), Repair of cracks that appear after 8 minutes.

[0049] Example 6: Response and drug release of a hydrogel capable of responding to and eliminating reactive oxygen species When NPH is in a reactive oxygen species environment, the NP, which acts as a cross-linking agent, will respond to ROS by decomposing and releasing the functional molecule nicotinamide and biocompatible decay substances. Figure 7 A) After adding an appropriate amount of hydrogen peroxide to a deuterium aqueous solution of NP, 1H NMR was performed, showing corresponding 1H peaks for both substances, confirming the successful conduct of the response reaction. Zeta potential measurements before and after the ROS response of NP showed a state transition from positive to negative. This is because the pyridine protonation inherent in NP provides a positive potential, while after the response, the pyridine protonation is reduced, and NP decomposes into nicotinamide. The conjugated π-electron system of the pyridine ring can adsorb OH⁻ ions from water, giving the surface a weak negative charge. Based on this, Zeta potential measurements of a mixed solution of NP and PVA showed the same trend, proving that even when NP and PVA form a phenylboronic acid ester bond, NP decomposition still occurs, breaking the bond with PVA. When NPH is placed in a ROS environment, UV analysis showed an increase in absorbance of the corresponding peak (…). Figure 7E). Furthermore, high-performance liquid chromatography analysis of the time-varying extract of NPH after ROS response showed that the gel continuously released nicotinamide over six hours, but could not effectively release the drug in an environment lacking reactive oxygen species.

[0050] Example 7: Test of reactive oxygen species scavenging ability of drug-releasing hydrogels that can respond to and scavenge reactive oxygen species The antioxidant effect of ABTS was performed on NPH in the group. Figure 8 A) showed that the introduction of NP resulted in highly efficient scavenging of ABTS free radicals. L929 cells were co-cultured with culture media containing hydrogen peroxide and different groups of NPH extracts, and then subjected to fluorescence staining and imaging. Figure 8 B), comparing the negative and positive groups, it can be seen that as NP increases, the green fluorescence representing reactive oxygen species damage weakens, indicating that the ability to scavenge reactive oxygen species gradually improves.

[0051] Example 8: Biocompatibility of Hydrogels Responsive to and Eliminating Reactive Oxygen-Releasing Drugs The NPH extracts from the grouped cells were co-cultured with L929 cells in culture medium, and the absorbance was measured after 24 h and 48 h using a microplate reader. Figure 9 A), processed using the formula, showed that L929 cells co-cultured with the extract exhibited similar proliferation to the control group cells without the extract, verifying the good cell compatibility of NPH. Hemolysis levels were analyzed in different groups of NPH cells. Figure 9 B), it was found that NPH had good hemolysis levels under different groups, and the hemolysis level of the gel gradually improved with the increase of NP.

[0052] Example 9: Application of responsive and reactive oxygen-releasing drug-eluting hydrogels as adhesives Healthy 3-month-old male Kunming mice were selected. After anesthetizing with isoflurane gas, the fur on the back of the mice was removed, and a linear incision of approximately 1 cm in length was created on the back of the mice using a scalpel to simulate a surgical incision. The control group underwent wound treatment with sutures, while the experimental group had their wounds sealed with NPH. The mice in both groups were observed at different time points. Figure 10 A), was euthanized seven days later for testing. The femtosecond laser testing results showed ( Figure 10(B) In the gel treatment group, the dermis showed a good growth trend, complete closure of the dermis, and abundant collagen fibers. In HE staining, the control group showed dense nuclei arranged along the wound, indicating an inflammatory response to acute injury. The experimental group showed no significant inflammatory response, demonstrating that NPH promotes wound healing and counteracts inflammatory responses caused by injury. NPH is easy to use in wound incisions, prevents secondary damage from suturing in mice, and promotes full-thickness development, showing great potential for clinical application.

[0053] Example 10: Application of responsive and reactive oxygen-releasing hydrogels in skin defects Healthy male SD rats weighing 300g were selected. After anesthetizing the rats with isoflurane gas, the fur on their backs was removed, and circular marks of equal area were made. Then, circular full-thickness skin of equal thickness was removed using scissors to create a dorsal wound. The control group received no treatment, while the experimental group had their wounds sealed with NPH dressings. Rats in both groups were observed at different time points. Figure 11 A), the mice were sacrificed two weeks later for testing. After integrating the wound images of the backs of the two groups of mice at different time points, the recovery rate of the wound area was calculated using a formula. Figure 11 B). The results showed that the NPH group exhibited a significant healing-promoting function compared to the control group. In pathological staining, the epidermis in the control group was incompletely healed and discontinuous, with red staining in the dermis and slow collagen fiber formation. In the experimental group, the epidermis healed continuously, and homogeneous new collagen fibers appeared in the dermal regeneration area, indicating that the experimental group had a better healing speed and quality than the control group, demonstrating the value of NPH in wound healing applications.

[0054] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A hydrogel with ROS-responsive controlled drug release and high tensile strength and viscosity, characterized in that, Using nicotinamide prodrug NP as a non-covalent crosslinking agent, polyvinyl alcohol PVA and 2-acrylamido-2-methylpropanesulfonic acid AMPS are bridged; on this basis, a covalent crosslinking network is formed by thermally initiated copolymerization of AMPS and acrylamide AM, thereby constructing a stable bi-crosslinked hydrogel framework.

2. The method for preparing a ROS-responsive, controlled-release hydrogel with high tensile strength and high viscosity as described in claim 1, characterized in that, The method includes the following steps: S1. Dissolve AMPS in water until fully dissolved; S2. Neutralize the solution obtained in step S1 to maintain its pH value at a slightly alkaline level; S3. Add PVA and AM to the solution obtained in step S2, heat and stir until completely dissolved; S4. Add NP to the solution obtained in step S3 and stir to dissolve; wherein, the NP structure is... ; S5. Dissolve MBA and 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide] in water until fully dissolved; S6. Add the solution obtained in step S5 to the solution in step S4 according to the set ratio, and mix well. S7. Nitrogen gas is introduced into the mixed solution prepared in step S6 to remove oxygen, and then a thermally initiated polymerization reaction is carried out to form a double crosslinked hydrogel.

3. The method for preparing a ROS-responsive, controlled-release hydrogel with high tensile strength and high viscosity as described in claim 2, characterized in that, The mass concentration of AMPS in the solution obtained from S1 is 3-8%.

4. The method for preparing a ROS-responsive, controlled-release hydrogel with high tensile strength and high viscosity as described in claim 2, characterized in that, In S2, the pH is 7.5~8.

5.

5. The method for preparing a ROS-responsive, controlled-release hydrogel with high tensile strength and high viscosity as described in claim 2, characterized in that, The mass concentration of PVA and AM in the solution obtained by S3 is 5-15%.

6. The method for preparing a ROS-responsive, controlled-release hydrogel with high tensile strength and high viscosity as described in claim 2, characterized in that, The mass concentration of nicotinamide prodrug in the solution obtained in S4 is 0%~25%, excluding 0%.

7. The method for preparing a ROS-responsive, controlled-release hydrogel with high tensile strength and high viscosity as described in claim 2, characterized in that, S6 The mass concentration of MBA in the resulting solution was 0.03~0.08%, and the mass concentration of 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide] was 0.05~0.15%.

8. The method for preparing a ROS-responsive, controlled-release hydrogel with high tensile strength and high viscosity as described in claim 2, characterized in that, In S7, the polymerization reaction time is 10~15h; the reaction temperature is 85~95℃.

9. The use of the ROS-responsive controlled-release hydrogel of claim 1 and having high tensile strength and high viscosity, or the hydrogel prepared by any one of claims 2 to 8, in the preparation of drugs or dressings for repairing cuts, abrasions or various wounds.

10. The use as described in claim 9, characterized in that, The wound is a linear wound repair and / or a facial wound repair.

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