Curcumin-modified polyigkonate-based hydrogel, preparation method and wound repair application thereof

Abstract

The application discloses a curcumin modified polyitaconate-based hydrogel, a preparation method and a wound repair application, and belongs to the technical field of biomedical materials and wound repair. The hydrogel is composed of a multi-block covalent graft polymer formed by covalent esterification reaction of a polyitaconate pre-polymer, polyethylene glycol, pluronic F127 and curcumin. The application aims to solve the technical problems that the existing wound dressing has single function, is insufficient in conformal covering capacity for irregular wounds, causes burst release and poor stability due to physical drug embedding, lacks sprayability and in-situ gelation capacity in response to body temperature, and the preparation process is harsh and it is difficult to realize the comprehensive repair of the drug-resistant bacteria infected wound in the aspects of sustained antibacterial, anti-inflammatory, antioxidant and tissue regeneration.

Description

Technical Field

[0001] This invention belongs to the field of biomedical materials and wound repair technology, specifically relating to a curcumin-modified polyitacrylate hydrogel, its preparation method, and its application in wound repair. Background Technology

[0002] Infected wounds, especially those caused by methicillin-resistant Staphylococcus aureus (MRSA) and other multidrug-resistant bacteria, pose a significant challenge to clinical wound repair. These wounds are typically characterized by persistent bacterial colonization, inflammatory imbalance, tissue necrosis, impaired angiogenesis, and delayed reepithelialization, making them highly susceptible to chronic non-healing and even leading to chronic inflammation, deep infections, and serious complications. With the increasing prominence of antibiotic resistance, traditional wound management methods relying on mechanical debridement, broad-spectrum antibiotic administration, and frequent dressing changes are no longer sufficient to simultaneously address the multiple challenges of bacterial infection, inflammatory imbalance, tissue loss, and delayed regeneration. Particularly under conditions of MRSA infection, conventional antibiotic treatment has limited efficacy, and long-term antibiotic use may further exacerbate the risk of resistance. An ideal wound dressing should not only form a physical protective barrier, but also play a comprehensive regulatory role in the hemostasis, inflammation, proliferation and remodeling phases of wound healing. Specifically, it should have good biocompatibility, tissue adhesion, moisture retention and breathability, antibacterial and anti-inflammatory properties, as well as the ability to promote collagen deposition, angiogenesis and epidermal regeneration.

[0003] Hydrogel materials, due to their high water content, good softness, excellent biocompatibility, and ability to maintain a moist wound microenvironment, have been widely used as wound dressings. Among them, thermoresponsive hydrogels exhibit good fluidity at low temperatures and can be applied via injection, coating, or spraying. Upon contact with the wound and reaching near body temperature, they undergo a sol-gel transition, forming a stable three-dimensional gel network, thereby achieving conformal coverage and local protection for irregular wounds. However, existing hydrogels often suffer from the following shortcomings: limited functionality and lack of multi-target synergistic therapeutic capabilities; drug delivery is mostly physically embedded, leading to burst release and stability issues; thermoresponsive materials often rely on exogenous cross-linking or have simple structures; they struggle to achieve conformal coverage of irregular wounds; and they lack the ability to regulate the immune microenvironment. Therefore, there is an urgent need for a multifunctional hydrogel material that combines sprayability, in-situ gelation ability, and antibacterial, anti-inflammatory, and regenerative functions. Itaconic acid is an endogenous immune metabolite with anti-inflammatory, antibacterial, and immune microenvironment-regulating activities. Polyitanconic acid ester materials based on itaconic acid or its derivatives show promising applications in the field of biomedical hydrogels due to their good structural designability and potential bioactivity. Curcumin is a natural polyphenol with multiple biological functions, including antibacterial, anti-inflammatory, antioxidant, immunomodulatory, and angiogenesis-promoting effects. It has high value in the repair of infected wounds, but it suffers from poor water solubility, insufficient stability, low bioavailability, and rapid in vivo clearance. Introducing curcumin covalently into hydrogel networks is expected to significantly improve its loading stability, reduce burst release, and enhance the system's sustained antibacterial, anti-inflammatory, and antioxidant capabilities.

[0004] However, existing wound dressings and related hydrogel systems for infected wounds still have many shortcomings. Most existing wound dressings only provide physical coverage or simple moisturizing, lacking inherent antibacterial, anti-inflammatory, antioxidant, and tissue regeneration-promoting functions. They are unable to comprehensively regulate the complex pathological microenvironment of infected wounds, limiting repair efficiency and quality. Conventional hydrogel dressings are mostly sheet-like or pre-formed, which are insufficient for conformally covering wounds with complex shapes, varying depths, or irregular edges, easily leading to problems such as insufficient adhesion, local gaps, and incomplete protection. Although some thermoresponsive hydrogels can gel near body temperature, their drug loading methods mostly rely on physical embedding or simple mixing. The active ingredients are released rapidly and have a short local retention time, failing to achieve a sustained and stable therapeutic effect. In the application of curcumin, existing hydrogel systems mostly use physical encapsulation to load curcumin. Due to curcumin's poor water solubility, poor stability, and easy rapid clearance, physical encapsulation cannot effectively solve the problems of uncontrollable release, insufficient loading stability, and limited long-term effects. Furthermore, the preparation of existing polyitacrylate-based hydrogels mostly relies on free radical polymerization, chemical initiation, or radiation initiation, which requires high precision in reaction conditions and process control. Some systems pose biosafety risks due to residual initiators or complex byproducts, and the preparation process is not gentle enough, hindering further promotion in the field of biomedical dressings. At the same time, these hydrogels generally lack good sprayability, shear-thinning properties, and temperature-responsive gel behavior, making it difficult to quickly and uniformly cover wounds and form stable gels in situ using simple spraying methods. This limits their practical application in large-area, irregular, or infected wounds.

[0005] In summary, current technologies lack a hydrogel dressing that is relatively simple to prepare, has safe ingredients, is easy to use, and possesses properties such as sprayability, temperature-responsive in-situ gelation, sustained antibacterial and anti-inflammatory effects, strong antioxidant properties, and tissue regeneration promotion, while also providing conformal coverage and comprehensive regulation for irregular infected wounds. Therefore, developing a curcumin-modified polyitacrylate-based sprayable hydrogel to meet the need for efficient repair of drug-resistant bacterial infected wounds has significant clinical and research value. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the present invention aims to provide a curcumin-modified polyitacrylate hydrogel, its preparation method, and its application in wound repair. This invention addresses the technical problems of existing wound dressings, such as limited functionality, insufficient conformal coverage for irregular wounds, drug physical embedding leading to burst release and poor stability, lack of sprayability and temperature-responsive in-situ gelation capability, and demanding preparation processes, making it difficult to achieve comprehensive repair of drug-resistant infected wounds through sustained antibacterial, anti-inflammatory, antioxidant, and tissue regeneration-promoting effects.

[0007] To achieve the above objectives, the present invention employs the following technical solution: This invention provides a method for preparing curcumin-modified polyitancone hydrogel, comprising the following steps: S1, under nitrogen protection, itaconic acid and polycaprolactone triol are mixed and melted, then p-toluenesulfonic acid monohydrate is added as a catalyst and melted again. Then, the first esterification reaction is carried out under vacuum. After the reaction is completed, itaconic acid is dissolved in organic solvent, purified by dialysis and freeze-dried to obtain polyitaconic acid ester prepolymer. S2, under nitrogen protection, the polyitacrylic acid ester prepolymer was melted, and then polyethylene glycol, Pluronic F127 and curcumin were added and melted. Then, a second esterification reaction was carried out under vacuum to covalently graft the components. After the reaction was completed, the polymer was dissolved in deionized water, purified by dialysis and freeze-dried to obtain a multi-block covalently grafted polymer. S3, the multi-block covalently grafted polymer is dissolved in deionized water at low temperature to prepare a polymer solution, and then subjected to sol-gel transition at physiological temperature to obtain the hydrogel.

[0008] In one embodiment, in S1, the molar ratio of itaconic acid to polycaprolactone triol is (10-20):1, and the molar ratio of the catalyst to polycaprolactone triol is (0.08-0.25):1. Preferably, the molar ratio of itaconic acid to polycaprolactone triol is 15:1, and the molar ratio of the catalyst to polycaprolactone triol is 0.16:1.

[0009] In one embodiment, in S1, the melting temperature is 130~150 °C and the time is 15~30 min; the temperature of the first esterification reaction is 130~150 °C and the time is 8~12 h. Preferably, the melting temperature is 140 °C and the time is 20 min, and the esterification reaction temperature is 140 °C and the time is 10 h.

[0010] In one embodiment, in S2, the molar ratio of the polyitacrylate prepolymer, polyethylene glycol, Pluronic F127 and curcumin is 1:1:1:1.

[0011] In one embodiment, in S2, the number-average molecular weight of the polyethylene glycol is 1500 g / mol.

[0012] In one embodiment, in S2, the melting temperature is 130~150 °C and the time is 15~30 min; the temperature of the second esterification reaction is 130~150 °C and the time is 8~12 h. Preferably, the melting temperature is 140 °C and the time is 20 min, and the esterification reaction temperature is 140 °C and the time is 10 h.

[0013] In one embodiment, in S3, the mass-volume concentration of the polymer solution is 25% to 30%.

[0014] In one embodiment, in S3, the temperature of the low-temperature condition is 4~10°C; the physiological temperature is 35~37°C.

[0015] The present invention also provides a hydrogel prepared by the above-mentioned method for preparing curcumin-modified polyitacrylic acid ester hydrogel, wherein the hydrogel is a flowable sol at a temperature of 4~10 ℃ and is applied by spraying to form a gel in situ at a body temperature of 35~37 ℃.

[0016] The present invention also provides the application of the above-mentioned curcumin-modified polyitacrylamide hydrogel in the repair of infected wounds. The curcumin-modified polyitacrylamide hydrogel is applied to the wound surface by spraying, injection or coating. The infected wounds include infected skin wounds caused by Staphylococcus aureus or methicillin-resistant Staphylococcus aureus.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a method for preparing curcumin-modified polyitaconate-based hydrogels. A polyitaconate prepolymer is prepared using a melt esterification method. The polyitaconate prepolymer, polyethylene glycol, Pluronic F127, and curcumin are then covalently grafted through a one-step melt esterification reaction to construct a multi-block polymer network. This method avoids the residual risks, cumbersome operations, and complex process control associated with free radical initiation, exogenous crosslinking agents, and multi-step activation coupling. Regarding the introduction of the active ingredient, this invention innovatively utilizes the esterification reaction between the hydroxyl groups in the curcumin molecule and the carboxyl groups in the polymer molecular chain, covalently grafting curcumin onto the polymer backbone via ester bonds, rather than using traditional physical embedding methods. This covalent fixation strategy effectively overcomes the problems of poor water solubility, easy diffusion and loss, and insufficient loading stability of curcumin. It significantly enhances the retention capacity of curcumin at the wound site, reduces initial burst release, and achieves continuous and stable release of the active ingredient, thereby providing long-term antibacterial, anti-inflammatory, and antioxidant effects, offering a more stable and lasting guarantee for promoting wound healing. From the perspective of thermosensitive performance, this invention constructs a thermosensitive polymer network by synergistically introducing polyethylene glycol and Pluronic F127. This allows the resulting polymer solution to maintain fluidity at low temperatures and undergo a sol-gel transition at physiological temperatures, forming a stable three-dimensional gel network in situ on the wound surface. This solves the problems of easy loss of liquid preparations and the difficulty of pre-formed hydrogels adhering to complex wounds. From the perspective of spraying and conformal coverage, the polymer solution obtained by this invention has shear-thinning properties, allowing it to be applied to the wound surface by spraying, injection, or coating. After the shear effect disappears and the temperature rises, it gels in situ, achieving uniform coverage and stable protection for large-area wounds of varying depths or irregular edges. This improves upon the shortcomings of traditional sheet dressings, such as insufficient adhesion, local gaps, and incomplete coverage. From the perspective of the repair effect of infected wounds, the synergistic effect of polyitacrylate structure, covalently grafted curcumin and moist three-dimensional network is beneficial to inhibit MRSA growth, reduce wound bacterial load, alleviate excessive inflammation and oxidative stress, and provide a suitable microenvironment for cell survival, migration, angiogenesis and orderly collagen deposition, thereby promoting tissue regeneration and wound closure and reducing the risk of abnormal fibrosis.

[0018] In summary, this invention solves the problems of existing infectious wound dressings, such as complex preparation processes, unstable active ingredient loading, insufficient conformal coverage, relatively limited functions, and difficulty in simultaneously addressing infection control and tissue repair.

[0019] The curcumin-modified polyitaconate-based sprayable hydrogel provided by this invention possesses excellent comprehensive therapeutic capabilities for infected wounds. This hydrogel combines sprayability, shear-thinning properties, and body temperature-triggered sol-gel transition, enabling injection or spray application at low temperatures and rapid in-situ gel formation on the wound surface, achieving uniform coverage and stable protection for irregular wounds. By introducing an itaconic acid-derived structure and covalently binding curcumin, the polyitaconate is incorporated into the wound dressing, endowing the material with anti-inflammatory, antibacterial, and wound microenvironment-regulating abilities. It possesses excellent endogenous antibacterial, anti-inflammatory, and antioxidant activities, effectively inhibiting MRSA growth, reducing bacterial load on the wound, and suppressing excessive inflammatory responses by regulating inflammation-related signaling pathways, thus improving the wound microenvironment. Simultaneously, this hydrogel exhibits good biocompatibility and blood compatibility, supporting cell survival and endothelial migration, promoting angiogenesis and orderly collagen deposition, accelerating tissue regeneration and wound closure, and reducing the risk of excessive fibrosis. Furthermore, loading active ingredients via covalent bonding effectively improves their stability and local retention time, avoiding burst release effects and achieving sustained and stable therapeutic effects. Loading or binding curcumin into the hydrogel system can improve its local retention capacity and sustained effect. In particular, introducing curcumin covalently into the hydrogel network can effectively improve its loading stability, reduce burst release phenomena, and enhance the hydrogel's sustained antibacterial, anti-inflammatory, and antioxidant capabilities. This invention develops a polyitancone-based hydrogel dressing that combines sprayability, thermally responsive gelation properties, antibacterial properties, anti-inflammatory properties, antioxidant properties, and tissue repair-promoting functions, which is of great significance for the treatment of drug-resistant bacterial infected wounds. The preparation process of this invention is mild, requires no exogenous cross-linking agents, has good clinical translation potential, and can be used as a multifunctional repair dressing for infected and drug-resistant bacterial wounds. Attached Figure Description

[0020] Figure 1 The physicochemical structure and characterization of the FPIC polymer in this invention are shown in Figure a: a schematic diagram of the synthesis route of the FPIC polymer; b: the proton NMR spectrum of the FPIC polymer.

[0021] Figure 2 The physicochemical properties of the FPIC hydrogel in this invention are as follows: a represents the temperature-dependent sol-gel transition behavior of the FPIC hydrogel; bd represents the injectability, spreadability, and sprayability of the FPIC hydrogel.

[0022] Figure 3 The bioactivity of the FPIC hydrogel in this invention is as follows: ac is the evaluation of the antioxidant capacity of the FPIC hydrogel; df is the evaluation of the anti-inflammatory capacity of the FPIC hydrogel; gh is the evaluation of the cell migration promotion capacity of the FPIC hydrogel; and ij is the evaluation of the angiogenesis promotion capacity of the FPIC hydrogel.

[0023] Figure 4 The following is an illustration of the effect of FPIC hydrogel in promoting the healing of infected wounds in this invention: a) is a schematic diagram of the animal experiment process; b) is a comparison of the wound appearance of the control group, PWG group, F127 hydrogel group and FPIC hydrogel group on days 0, 3, 7 and 14; c) is a plate photograph of bacterial culture of wound tissue on days 3 and 7.

[0024] Figure 5 This is a histological evaluation of the FPIC hydrogel's ability to promote wound healing in infected areas in this invention: a) H&E staining results of wound tissues during treatment in each group; b) Masson staining results of wound tissues in each group on day 14; cd) quantitative analysis of IL-6 and iNOS in wound tissues in each group on day 3; ef) quantitative analysis of CD31 and TGF-β1 in wound tissues in each group on day 14.

[0025] Figure 6 This is a schematic diagram illustrating the preparation method and application of a curcumin-modified polyitacrylate-based hydrogel according to the present invention. Detailed Implementation

[0026] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0027] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0028] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0029] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0030] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0031] This invention aims to provide a curcumin-modified polyitacrylate-based sprayable hydrogel and its preparation method. Through molecular structure design, it achieves synergistic therapeutic functions of antibacterial, anti-inflammatory, antioxidant and tissue regeneration promotion, and is used for the repair of wounds infected by drug-resistant bacteria.

[0032] In the aforementioned curcumin-modified polyitancone-based sprayable hydrogel, the polymer is first copolymerized from polyitancone prepolymer, polyethylene glycol, Pluronic F127, and curcumin via a one-step melt esterification reaction. Curcumin is chemically bonded to the polymer molecular chain via covalent bonds. A 25% (w / v) aqueous solution prepared from this polymer exhibits concentration-dependent temperature-responsive sol. Gel transition characteristics: It is a free-flowing liquid at 4 ℃, an injectable viscous state with limited flowability at 25 ℃, and transforms into a non-flowing, stable gel state at 37 ℃. This hydrogel can be applied to wounds via spraying, injection, or coating, and gels in situ at body temperature to form a conformally fitting three-dimensional network. Animal experiments show that this hydrogel, in a methicillin-resistant Staphylococcus aureus (MRSA) infected full-thickness wound model, possesses multiple functions including accelerating wound closure, potent antibacterial activity, inhibiting inflammation, promoting angiogenesis and orderly collagen remodeling, and a lower risk of fibrosis, demonstrating broad application prospects in the repair of infected wounds.

[0033] This embodiment provides a curcumin-modified polyitaconate-based sprayable hydrogel, which is composed of a multi-block covalently grafted polymer formed by covalent esterification of polyitaconate prepolymer with polyethylene glycol, Pluronic F127 and curcumin.

[0034] In this embodiment, the polyitaconate prepolymer is prepared by melt esterification of itaconic acid and polycaprolactone triol under acid catalysis. Polyethylene glycol is used to improve the polymer's hydrophilicity and chain flexibility, Pluronic F127 is used to impart temperature responsiveness and sol-gel transition properties to the material, and curcumin is introduced into the polymer network via covalent bonds to impart antibacterial, anti-inflammatory, and antioxidant activities.

[0035] The resulting hydrogel material is in a flowable sol state at low temperatures, and undergoes a sol-gel transition at temperatures close to human body temperature, forming a stable three-dimensional gel network structure in situ. It also exhibits multiple biological activities, including antibacterial, anti-inflammatory, antioxidant, and tissue regeneration promotion.

[0036] Specifically, the preparation method of the polyitacrylic acid ester prepolymer includes the following steps: Under nitrogen protection, itaconic acid and polycaprolactone triol were mixed in a molar ratio and premixed under set melting conditions. Then, p-toluenesulfonic acid monohydrate was added as a catalyst for melting, followed by a first esterification reaction under vacuum to obtain a crude product. Subsequently, the crude product was dissolved in an organic solvent, purified by dialysis, and freeze-dried to obtain the polyitaconic acid ester prepolymer.

[0037] The molar ratio of itaconic acid to polycaprolactone triol is (10-20):1, and the molar ratio of the catalyst to polycaprolactone triol is (0.08-0.25):1. The melting temperature during the preparation of the polyitaconic acid ester prepolymer is 130-150 °C, and the melting time is 15-30 min. The temperature of the first esterification reaction is 130-150 °C, and the melting time is 8-12 h.

[0038] More preferably, the molar ratio of itaconic acid to polycaprolactone triol is 15:1, the molar ratio of catalyst to polycaprolactone triol is 0.16:1, the set melting conditions are a temperature of 140°C, a premixing time of 20 min, and a catalyst melting time of 20 min; the temperature of the first esterification reaction is 140°C, the time is 10 h, the vacuum conditions are -0.085 MPa to -0.095 MPa, the organic solvent used is dimethyl sulfoxide, the dialysis conditions are dialysis purification using a dialysis bag with a molecular weight cutoff of 3500 Da for 2 days, and the specific parameters for freeze drying are: temperature -75°C to -80°C, vacuum degree 2 to 10 Pa.

[0039] Based on this, the method for preparing the multi-block covalently grafted polymer includes the following steps: Under nitrogen protection, the polyitacrylic acid ester prepolymer was melted, and then polyethylene glycol, Pluronic F127, and curcumin were added and melted. The polyitacrylic acid ester prepolymer was then mixed with polyethylene glycol, Pluronic F127, and curcumin in a molar ratio of 1:1:1:1 and reacted under vacuum to allow the components to undergo a second esterification reaction to form a covalent graft structure. The reaction product was dissolved in deionized water, purified by dialysis, and freeze-dried to obtain the final polymer.

[0040] In the preparation of the multi-block covalent grafted polymer, the melting temperature is 130~150 ℃ and the time is 15~30 min; the temperature of the second esterification reaction is 130~150 ℃ and the time is 8~12 h.

[0041] More preferably, the melting temperature is 140°C, the temperature of the second esterification reaction is 140°C, and the time is 10 hours.

[0042] The polyethylene glycol used had an average number-average molecular weight of 1500 g / mol, and the relative molecular mass of Pluronic F127 was ~12600 g / mol. The vacuum conditions were -0.085 MPa to -0.095 MPa. The dialysis purification conditions were dialysis purification for 2 days using a dialysis bag with a molecular weight cutoff of 10000 Da. The specific parameters for freeze drying were: temperature -75℃ to -80℃, and vacuum degree 2 to 10 Pa.

[0043] In the above hydrogel structure, curcumin is covalently fixed in the polymer network through ester bonds, thereby achieving the structural and stable introduction of the active ingredient and effectively avoiding the burst release problem that may be caused by traditional physical encapsulation methods.

[0044] Furthermore, Pluronic F127 and polyethylene glycol (PEG) jointly participate in the construction of the polymer network as structural control units. Pluronic F127 imparts temperature responsiveness and sol-gel transition properties to the material, allowing the hydrogel to remain in a sol state at 4–10°C to room temperature, while rapidly gelling at 35–37°C. PEG, on the other hand, imparts hydrophilicity and segmental flexibility to the material. This hydrogel exhibits fluidity at low temperatures and displays shear-thinning behavior under external forces. It can be applied to wounds via spraying, injection, or coating, and recovers its gel structure under static conditions.

[0045] In terms of application, the prepared hydrogel polymer is usually formulated into a solution with a mass-volume concentration of 20% to 30%, preferably 25%.

[0046] It is worth emphasizing that the hydrogel material in this embodiment does not use any exogenous crosslinking agents or free radical initiators in the entire preparation and gelation process, and its composition is safe and has good biocompatibility.

[0047] This hydrogel material is primarily used for the repair and treatment of infected skin wounds, including but not limited to those caused by Staphylococcus aureus or methicillin-resistant Staphylococcus aureus (MRSA). For detailed evaluation results of its in vivo antibacterial activity and wound repair efficacy, please refer to [link to relevant documentation]. Figure 4 and Figure 5 part.

[0048] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0049] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0050] Example 1 This embodiment provides a method for preparing polyitancone prepolymer (bPI), the specific steps of which are as follows: The raw materials were weighed according to a molar ratio of itaconic acid, polycaprolactone triol, and p-toluenesulfonic acid monohydrate of 15:1:0.16. Itaconic acid and polycaprolactone triol were placed in a reaction vessel and heated to 140 °C under nitrogen protection, and held at this temperature for 20 min to allow the itaconic acid and polycaprolactone triol to fully melt and mix uniformly. Then, p-toluenesulfonic acid monohydrate was added to the molten system, and stirring and mixing continued, with the mixture held at 140 °C for 20 min under nitrogen protection. The p-toluenesulfonic acid monohydrate acts as a catalyst for the esterification reaction, promoting the esterification of the carboxyl groups in itaconic acid with the hydroxyl groups in polycaprolactone triol. Afterward, the reaction system was placed under vacuum and reacted at 140 °C for 10 h to obtain crude bPI product. After the reaction, the crude bPI product was dissolved in dimethyl sulfoxide and purified by dialyzing for 2 days using a dialysis bag with a molecular weight cutoff of 3500 Da to remove unreacted small monomers, catalysts, and other low-molecular-weight impurities. After dialysis, the dialysate was centrifuged, the precipitate was collected, washed twice with deionized water, and then freeze-dried under vacuum to obtain the bPI prepolymer. This prepolymer can be used as an intermediate for the subsequent preparation of curcumin-modified polyitacrylate-based polymers.

[0051] Example 2 This embodiment provides a method for preparing curcumin-modified polyitancone ester polymer (FPIC), the specific steps of which are as follows: Weigh out the raw materials according to a molar ratio of bPI prepolymer, polyethylene glycol, Pluronic F127, and curcumin of 1:1:1:1. Place the bPI prepolymer in a reaction vessel and heat to 140 °C under nitrogen protection, maintaining the temperature for 20 min to allow the bPI prepolymer to fully melt. Subsequently, add polyethylene glycol, Pluronic F127, and curcumin to the above melt system, and continue melting for another 20 min. The polyethylene glycol is used to improve the hydrophilicity and segmental flexibility of the polymer, and its average number-average molecular weight is 1500 g / mol; Pluronic F127 imparts temperature responsiveness and sol-gel transition properties to the polymer; and curcumin imparts antibacterial, anti-inflammatory, and antioxidant activities to the polymer. The above reaction system was reacted under vacuum at 140 °C for 10 h to allow the bPI prepolymer to undergo further esterification with polyethylene glycol, Pluronic F127, and curcumin. This introduced polyethylene glycol segments, the temperature-sensitive F127 segment, and the active structure of curcumin into the polyitancone ester polymer system, yielding crude FPIC product. After the reaction, the product was dissolved in deionized water, and the crude FPIC product was purified by dialysis using a dialysis bag with a molecular weight cutoff of 10000 Da for 2 days to remove unreacted small molecules and low-molecular-weight impurities. After dialysis, the dialysate was centrifuged, and the supernatant was collected and freeze-dried under vacuum to obtain the FPIC polymer.

[0052] Example 3 This embodiment provides a method for preparing FPIC sprayable hydrogel, the specific steps of which are as follows: The FPIC polymer prepared in Example 2 was added to deionized water and stirred at 4 °C until fully dissolved, to prepare FPIC polymer aqueous solutions with mass-volume concentrations of 20%, 25%, and 30%, respectively. Sol-gel analyses of the solutions at each concentration were conducted at room temperature (25 °C) and physiological temperature (37 °C). The gel transformation behavior was investigated, and the results showed that at room temperature, the 20% solution remained a flowing liquid, the 25% solution was a viscous state with limited flowability but still injectable, and the 30% solution had formed a non-flowing, stable gel. At 37 °C, the 20% solution remained liquid, indicating insufficient gelation, while both the 25% and 30% solutions rapidly transformed into non-flowing, stable gels. Considering both clinical ease of operation and gelling performance under physiological conditions, the 25% concentration maintained a certain degree of flowability at room temperature to adapt to application on irregular wound surfaces and could rapidly gel in situ at body temperature. The 20% concentration, however, did not gel sufficiently at physiological temperatures, and the 30% concentration lost its flowability at room temperature, making it unsuitable for injection or spraying. Based on these optimal results, a 25% (w / v) FPIC polymer aqueous solution was incubated at 37 °C to induce a thermoresponsive sol. The gel transformation yields the FPIC sprayable hydrogel. This hydrogel exhibits good flowability at low or room temperature, allowing it to be applied to the wound surface via spraying, injection, or coating. Upon contact with the wound and reaching physiological body temperature, it gels in situ, forming a three-dimensional hydrogel network that conforms to the wound surface.

[0053] Example 4 This embodiment provides the application of the FPIC sprayable hydrogel described in Embodiment 3 in the repair of infected wounds. The specific steps are as follows: The 25% (w / v) FPIC polymer aqueous solution prepared in Example 3 was loaded into a spraying or injection device and kept in a fluid state at low or room temperature. It was then sprayed, injected, or applied to the surface of an infected wound. The infected wound included skin infections caused by Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, or other pathogenic bacteria. The FPIC polymer aqueous solution gelled in situ at the wound temperature, forming a continuous hydrogel layer covering the wound. This hydrogel layer maintained a moist microenvironment on the wound surface and exerted antibacterial, anti-inflammatory, and antioxidant effects synergistically through the polyitanone backbone and curcumin structure. Simultaneously, the temperature-responsiveness of Pluronic F127 enabled in situ conformal gelation, and the polyethylene glycol segments enhanced the material's hydrophilicity and biocompatibility, thereby promoting infection control, inflammation regulation, collagen deposition, re-epithelialization, and tissue regeneration, ultimately accelerating the healing process of the infected wound.

[0054] The following are specific examples of the application of FPIC sprayable hydrogel in the repair of infected wounds: In the initial stage of this study, a full-thickness skin wound model of methicillin-resistant Staphylococcus aureus (MRSA) infection was constructed. Six- to eight-week-old female ICR mice were selected and, after one week of acclimatization, anesthetized with tribromoethanol and their back hair was removed. A circular full-thickness excision wound (approximately 8 mm in diameter) was created on the back, and then MRSA suspension was inoculated into the wound bed to induce infection, thus obtaining the MRSA-infected full-thickness skin wound model.

[0055] Criteria for evaluating the therapeutic effect of FPIC hydrogel: (1) Healing: The wound is completely closed, the epithelialization is complete, the infection is completely controlled, the collagen deposition is sufficient and orderly arranged, the inflammatory response is significantly suppressed, the angiogenesis network is established, and the collagen is restored to normal levels.

[0056] (2) Significant effect: The wound is basically closed, the infection is significantly controlled, the granulation tissue is well matured, the inflammation is significantly reduced, the angiogenesis is significant, and the collagen deposition and collagen remodeling are significantly improved.

[0057] (3) Effective: The wound is partially closed, the infection is controlled, some re-epithelialization occurs, granulation tissue grows, the degree of inflammation is reduced, and collagen is initially deposited.

[0058] (4) Ineffective: The wound does not heal or continues to expand, the signs of infection do not improve or worsen, a large number of inflammatory cells infiltrate, poor re-epithelialization and granulation tissue formation, and sparse and disordered collagen deposition.

[0059] Treatment methods: The 25% (w / v) concentration FPIC sprayable hydrogel prepared in Example 3 was stored at 4 °C and brought to room temperature before use. The hydrogel was uniformly injected and applied to the surface of the MRSA-infected wound. Upon administration, it rapidly gelled in situ under body temperature, forming a three-dimensional hydrogel layer that conformally adhered to the wound surface. Wound healing was regularly observed and recorded during treatment, and the therapeutic effect was comprehensively evaluated according to the efficacy criteria. A 25% (w / v) concentration Pluronic F127 hydrogel was used as a thermosensitive matrix material control, and Prontosan wound gel (PWG, B. Braun) was used as a commercial positive control.

[0060] Treatment results: In an ICR mouse model of full-thickness MRSA infection, the healing-promoting effect of the sprayable FPIC hydrogel was evaluated, using F127 hydrogel and commercially available Prontosan wound gel (PWG) as controls. Results showed that the FPIC hydrogel group exhibited the fastest wound closure, with complete reepithelialization by day 14 and an epidermal thickness closest to normal skin, while the control group and F127 group still showed residual defects. Antibacterial experiments indicated that the FPIC group had almost no bacterial colonies, significantly superior to other groups. Histological and immunostaining further confirmed that the FPIC group had the richest and densest collagen deposition, the lowest expression of IL-6 and iNOS inflammatory factors, the highest density of CD31-positive microvessels, and significantly reduced TGF-β1 expression, suggesting a lower risk of fibrosis.

[0061] In summary, FPIC hydrogel possesses multiple functions, including accelerating wound closure, potent antibacterial activity, inhibiting inflammation, promoting angiogenesis and orderly tissue remodeling, and has the advantage of reducing the risk of fibrosis, demonstrating promising application prospects in the repair of infected wounds.

[0062] The experimental data will be analyzed in detail below: like Figure 1 As shown, Figure 1a is a schematic diagram of the synthesis route of the FPIC polymer. First, the bPI prepolymer is prepared by esterification of itaconic acid and polycaprolactone triol (PCL-triol); then, the bPI prepolymer is further esterified with polyethylene glycol (PEG), Pluronic F127 (F127) and curcumin to finally obtain the FPIC polymer. Figure 1 b shows the 1H NMR spectrum of the FPIC polymer and related precursors. PCL-triol exhibits a methyl proton (-C) at 0.81 ppm. H 3) Resonance signal, exhibiting methylene protons (-C) at 1.29, 1.54, 2.28, and 4.00 ppm. H 2-) Characteristic peaks. Itaconic acid shows vinyl protons (-C=C) at 5.77 and 6.15 ppm. H 2) Characteristic peak, showing a methylene proton (-C) at 3.30 ppm. H 2-) Characteristic peak. After the bPI prepolymer is formed, a new characteristic peak appears at 4.08 ppm, which can be attributed to the methylene proton (-COO-C) adjacent to the ester bond. H 2-), indicating a covalent coupling between itaconic acid and PCL-triol. Furthermore, new characteristic peaks appeared in the FPIC polymer spectrum, including the PEG and F127 methylene proton (-C) at approximately 3.60 ppm. H 2-) Characteristic peak, F127 methyl proton (-C) at 1.07 ppm H 3) Characteristic peaks, and curcumin-related olefin protons (-C) at approximately 7.02 and 7.51 ppm. H =C H -) and aromatic hydrogen (Ar-) H Characteristic peaks. Additionally, at approximately 4.00 ppm, the ester bond is adjacent to the methylene proton (-COO-C). H 2-) The enhanced peak intensity further proves that the FPIC polymer was successfully synthesized through esterification.

[0063] like Figure 2 As shown, Figure 2α represents the temperature-dependent sol-gel transition behavior of the FPIC hydrogel. At 4 °C, all concentrations of FPIC solutions remained free-flowing. Upon heating to 25 °C, the 20% FPIC solution remained liquid, the 30% FPIC solution formed a non-flowing gel, while the 25% FPIC solution exhibited some flow restriction. Further heating to 37 °C maintained the 20% FPIC solution in a liquid state, while both the 25% and 30% FPIC solutions transformed into non-flowing gels, indicating that FPIC exhibits significant thermally responsive gelation behavior at 25% and 30% concentrations. Based on these results, a 25% FPIC solution was chosen for the subsequent preparation of the FPIC hydrogel, as this concentration achieves a good balance between ease of handling and thermogelation performance. Figure 2 bd represents the injectability, spreadability, and sprayability of the FPIC hydrogel. At 25 °C, the FPIC hydrogel can be smoothly extruded using a syringe equipped with a 0.45 × 16 mm RWLB needle, maintaining good structural integrity after extrusion, indicating good injectability. Simultaneously, the FPIC hydrogel can spread uniformly on the surface of a glass slide at 25 °C, demonstrating good spreadability. Furthermore, since the F127-based hydrogel can be sprayed to uniformly cover irregular areas at 4 °C, it is beneficial for adapting to complex wound surfaces. Upon contact with the skin or wound surface, the local temperature increase induces rapid gelation of the hydrogel, thereby enhancing its retention capacity at the wound site and forming a protective barrier against external environmental stimuli.

[0064] like Figure 3 As shown, Figure 3 ac represents the antioxidant capacity of FPIC hydrogel. After co-incubation with 1,1-diphenyl-2-trinitrophenylhydrazine (DPPH) solution for 1 h, the control group and F127 hydrogel group solutions remained purple, while the FPIC hydrogel group and vitamin C (VC) group solutions gradually turned yellow, indicating a significant reduction in DPPH free radical levels. UV-Vis absorption spectroscopy results showed that the control group and F127 group exhibited a distinct DPPH characteristic absorption peak at 516 nm, while this absorption peak was significantly weakened or even disappeared in the FPIC hydrogel group and VC group. Further quantitative analysis showed that, compared with the control group, the free radical scavenging rates of both FPIC hydrogel and VC exceeded 90%, indicating that FPIC hydrogel has good antioxidant activity. Figure 3df represents the anti-inflammatory capacity of FPIC hydrogel. After stimulation with lipopolysaccharide (LPS), the expression levels of Il1β, Il6, and Tnfα in RAW 264.7 cells were significantly increased, indicating the successful establishment of the inflammation model. After co-incubation for 48 h, compared with the F127 hydrogel group, FPIC hydrogel significantly downregulated the expression levels of Il1β, Il6, and Tnfα, indicating that FPIC hydrogel can effectively inhibit the expression of inflammatory factors and has strong anti-inflammatory activity. Figure 3 The expression gh represents the ability of FPIC hydrogel to promote HUVEC cell migration. After 48 h of culture, compared with the control group and the F127 hydrogel group, the scratch area in the FPIC hydrogel group was significantly smaller, indicating a faster scratch closure speed. Quantitative results showed that the relative migration area in the FPIC group increased to over 84.7%, while that in the control group and the F127 group was approximately 54.9% and 56.8%, respectively, indicating that FPIC hydrogel can significantly promote HUVEC migration. Figure 3 ij represents the angiogenesis-promoting capacity of FPIC hydrogel. After 48 h of culture, the FPIC hydrogel-treated group formed a more pronounced and continuous capillary-like network structure, while the tubular structures in the control group and F127 group were relatively sparse. Statistical analysis of angiogenesis-related parameters showed that FPIC hydrogel significantly increased the number of nodes, connections, grids, and segments, while also increasing the total tube length, branch length, and segment length, indicating that FPIC hydrogel has good angiogenesis-promoting potential.

[0065] like Figure 4 As shown, Figure 4 A diagram illustrating the animal experiment procedure is shown below. First, a full-thickness skin defect model was constructed on the back of ICR mice, and MRSA suspension was added to induce infection. Subsequently, different hydrogels were used to treat the wounds, and the wound healing effect was systematically evaluated on days 3, 7, and 14 using indicators such as changes in wound area, bacterial infection status, tissue structure, expression of inflammation-related genes, and collagen deposition. Figure 4 b shows the changes in wound appearance on days 0, 3, 7, and 14 for the control group, PWG group, F127 hydrogel group, and FPIC hydrogel group. With prolonged treatment, the wound area decreased to varying degrees in each group. By day 14, the FPIC hydrogel group had the smallest wound defect area, with newly formed skin almost completely covering the wound. In contrast, slight unhealed areas were still observed in the control group, PWG group, and F127 hydrogel group, indicating that FPIC hydrogel can more effectively promote the repair of infected wounds. Figure 4c shows plate images of bacterial cultures from wound tissue on days 3 and 7. After 3 and 7 days of treatment, significant bacterial colony growth was still observed in the control group, PWG group, and F127 hydrogel group, while almost no bacterial colonies were observed in the FPIC hydrogel group. This indicates that FPIC hydrogel can effectively inhibit bacterial proliferation in wounds and has strong in vivo antibacterial capabilities.

[0066] like Figure 5 As shown, Figure 5 Figure a shows the H&E staining results of wound tissues during treatment in each group. On day 3, compared with the control group, PWG group, and F127 hydrogel group, the FPIC hydrogel group showed a thicker scab structure on the wound surface and exhibited more obvious early healing characteristics. By day 7, the FPIC hydrogel group had formed a relatively continuous and thin new epidermis, while the control group, PWG group, and F127 hydrogel group still showed varying degrees of incomplete epidermal coverage. By day 14, both the FPIC hydrogel group and PWG group had formed a continuous epidermal layer, which was significantly thinner than on day 7. Among them, the FPIC hydrogel group had the thinnest new epidermis and the tissue structure was closer to normal skin. These results indicate that FPIC hydrogel can accelerate epithelial regeneration and promote more complete wound closure. Figure 5 b shows the Masson staining results of wound tissues in each group on day 14. Masson trichrome staining showed that, compared with the control group and the F127 hydrogel group, both the FPIC hydrogel group and the PWG group exhibited more significant collagen deposition. Among them, the FPIC hydrogel group had the richest and densest distribution of collagen fibers, suggesting that it can effectively promote collagen deposition and tissue remodeling. Figure 5 The cf represents the statistical results of immunostaining. Further confirmation indicated that the FPIC group had the lowest expression of IL-6 and iNOS inflammatory factors, the highest density of CD31-positive microvessels, and significantly reduced TGF-β1 expression, suggesting a lower risk of fibrosis.

[0067] like Figure 6 As shown, the FPIC polymer is copolymerized from polyitacrylate prepolymer, polyethylene glycol, Pluronic F127, and curcumin via a one-step melt esterification reaction. Curcumin is chemically bonded to the polymer molecular chain via covalent bonds. The FPIC hydrogel exhibits temperature-responsive sol-gel transition properties and can be applied to wounds via injection or spraying, achieving conformal coverage of irregular wounds. This hydrogel combines antibacterial, anti-inflammatory, and antioxidant functions, inhibiting bacterial growth, alleviating excessive inflammation, and scavenging reactive oxygen species, thereby promoting angiogenesis and accelerating the healing of wounds infected with methicillin-resistant Staphylococcus aureus (MRSA).

[0068] In summary, FPIC hydrogel helps improve the skin regeneration process and promotes wound repair towards a more mature and orderly tissue structure.

[0069] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A method for preparing curcumin-modified polyitanone hydrogel, characterized in that, Includes the following steps: S1, under nitrogen protection, itaconic acid and polycaprolactone triol are mixed and melted, then p-toluenesulfonic acid monohydrate is added as a catalyst and melted again. Then, the first esterification reaction is carried out under vacuum. After the reaction is completed, itaconic acid is dissolved in organic solvent, purified by dialysis and freeze-dried to obtain polyitaconic acid ester prepolymer. S2, under nitrogen protection, the polyitacrylic acid ester prepolymer was melted, and then polyethylene glycol, Pluronic F127 and curcumin were added and melted. Then, a second esterification reaction was carried out under vacuum to covalently graft the components. After the reaction was completed, the polymer was dissolved in deionized water, purified by dialysis and freeze-dried to obtain a multi-block covalently grafted polymer. S3, the multi-block covalently grafted polymer is dissolved in deionized water at low temperature to prepare a polymer solution, and then subjected to sol-gel transition at physiological temperature to obtain the hydrogel.

2. The method for preparing curcumin-modified polyitanone-based hydrogel according to claim 1, characterized in that, In S1, the molar ratio of itaconic acid to polycaprolactone triol is (10-20):1, and the molar ratio of the catalyst to polycaprolactone triol is (0.08-0.25):

1.

3. The method for preparing curcumin-modified polyitanone-based hydrogel according to claim 1, characterized in that, In S1, the melting temperature is 130~150 ℃ and the time is 15~30 min; the temperature of the first esterification reaction is 130~150 ℃ and the time is 8~12 h.

4. The method for preparing curcumin-modified polyitanone-based hydrogel according to claim 1, characterized in that, In S2, the molar ratio of the polyitacrylic acid prepolymer, polyethylene glycol, Pluronic F127 and curcumin is 1:1:1:

1.

5. The method for preparing curcumin-modified polyitanone-based hydrogel according to claim 1, characterized in that, In S2, the number-average molecular weight of the polyethylene glycol is 1500 g / mol.

6. The method for preparing curcumin-modified polyitanone-based hydrogel according to claim 1, characterized in that, In S2, the melting temperature is 130~150 ℃ and the time is 15~30 min; the temperature of the second esterification reaction is 130~150 ℃ and the time is 8~12 h.

7. The method for preparing curcumin-modified polyitanone-based hydrogel according to claim 1, characterized in that, In S3, the mass-volume concentration of the polymer solution is 25%~30%.

8. The method for preparing curcumin-modified polyitanone-based hydrogel according to claim 1, characterized in that, In S3, the temperature of the low-temperature condition is 4~10℃; the physiological temperature is 35~37℃.

9. A curcumin-modified polyitanone-based hydrogel, characterized in that, The curcumin-modified polyitacrylate hydrogel was prepared by any one of claims 1 to 8. The hydrogel is a flowable sol at a temperature of 4 to 10 °C and is applied by spraying to form a gel in situ at a body temperature of 35 to 37 °C.

10. The application of the curcumin-modified polyitanone hydrogel according to claim 9 in the repair of infected wounds, characterized in that, The curcumin-modified polyitacrylate hydrogel is applied to the surface of the wound by spraying, injection or coating, and the infectious wound includes infectious skin wounds caused by Staphylococcus aureus or methicillin-resistant Staphylococcus aureus.

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