Injectable conductive anti-adhesion hydrogel as well as preparation method and application thereof

Abstract

The invention discloses injectable conductive anti-adhesion hydrogel and a preparation method and application thereof, hydrogel raw materials comprise a phytic acid doped hydrazide group-containing gelatin-based conductive polymer, an aldehyde group-containing amphiphilic block copolymer and a catalyst, and the three raw materials are mixed under body temperature and physiological conditions and then subjected to in-situ crosslinking to form the hydrogel. The hydrogel has the characteristics of rapid gelling, self-healing, injectability, electric conduction, oxidation resistance and the like. In-vivo experiments show that the hydrogel can significantly inhibit postoperative abdominal adhesion, reduce inflammatory response and remove active oxygen; meanwhile, the hydrogel can promote collagen deposition, angiogenesis and muscle regeneration, is suitable for abdominal wall defect repair and postoperative adhesion prevention, and solves the problem that an existing material is difficult to give consideration to adhesion prevention and repair promotion.

Description

Technical Field

[0001] This invention belongs to the field of biomedical materials technology, specifically relating to an injectable conductive anti-adhesion hydrogel, its preparation method, and its application. Background Technology

[0002] Abdominal adhesions and abdominal wall defects / reconstruction are two major challenges in abdominal surgery, primarily involving surgical materials and tissue repair techniques. Abdominal adhesions, a common complication after abdominal surgery, especially open surgery, can lead to serious problems such as chronic abdominal pain, intestinal obstruction, infertility, and difficulty in repeat surgery, even threatening life. To reduce the risk of adhesions, various anti-adhesion barrier materials are widely used clinically, such as absorbable films, gel / solution barriers, and biodegradable coatings based on natural polymers. These materials mainly reduce the contact between organs and the damaged surface through physical isolation, thereby reducing the occurrence of adhesions. On the other hand, abdominal wall defects / reconstruction is also a pressing problem in surgery. Existing tension-free repair methods mostly rely on synthetic mesh for support, but mesh can cause a series of complications, such as foreign body reaction, chronic inflammation, and lateral abdominal adhesions.

[0003] Numerous challenges exist in the prevention and treatment of abdominal adhesions and their application in abdominal wall defects / reconstruction. For anti-adhesion barrier materials, the continuously moist environment of the abdominal cavity and the dynamic traction effects of respiration and peristalsis place extremely high demands on the material's adhesion, stability, and durability. Existing products, such as film-type materials, are difficult to adhere to irregular or bleeding wounds, easily curling and shifting; gel-type materials form slowly or are easily diluted and washed away by body fluids, resulting in insufficient barrier duration; traditional hydrogels lack sufficient mechanical toughness, easily cracking under tension and failing to provide coverage; their adhesion strength is limited in moist environments, making it difficult to meet the needs of minimally invasive procedures; and simply providing physical isolation often fails to simultaneously regulate key adhesion-inducing factors such as inflammation, reactive oxygen species (ROS, i.e., active groups containing unpaired electrons formed by oxygen related to oxidative metabolism in organisms), and fibrosis, thus limiting the stability of the anti-adhesion effect. For abdominal wall repair materials, it is necessary to have high strength and deformation adaptability, as well as anti-adhesion performance and biocompatibility on the abdominal side. However, existing materials often cannot meet these requirements at the same time.

[0004] To address the aforementioned issues, existing technologies have undergone various attempts and improvements. To enhance the performance of anti-adhesion barrier materials, researchers have developed a variety of novel materials, such as self-healing hydrogels based on dynamic covalent bonds like Schiff bases and hydrazones / acylhydrazones. These materials exhibit shear-thinning and self-healing properties due to reversible cross-linking, making them suitable for minimally invasive injection and in-situ gelation. Simultaneously, conductive hydrogels are also being used for tissue repair and electrophysiological signal modulation to improve cell behavior and promote regeneration. For abdominal wall repair materials, researchers are dedicated to developing novel synthetic meshes or composite materials that possess both sufficient strength and good biocompatibility and anti-adhesion properties.

[0005] However, existing solutions still have many shortcomings. Self-healing hydrogels based on dynamic covalent bonds often face problems such as insufficient gelation kinetics, limited cross-linking density, and low mechanical properties under physiological pH and high water content environments. While physically cross-linked hydrogels relying solely on physical entanglement or ionic / hydrogen bonds form rapidly, they are easily diluted by body fluids or subjected to prolonged peristaltic disturbances, leading to structural relaxation. Although conductive hydrogels have the potential to improve cell behavior and promote regeneration, many conductive components suffer from poor doping stability, decreased electroactivity in the in vivo environment, or insufficient biosafety and processability, limiting their widespread application in peritoneal anti-adhesion and abdominal wall repair. Furthermore, existing materials often struggle to achieve differentiated mechanical matching in anti-adhesion and abdominal wall repair scenarios, failing to simultaneously meet the requirements of reducing frictional stimulation and providing sufficient support. Therefore, the development of an injectable in-situ gelling hydrogel system that combines stable conductive components, dynamic reversible cross-linking, and physically reinforced structures remains an urgent clinical need. Summary of the Invention

[0006] To address the shortcomings of existing anti-adhesion barrier materials in the complex environment of the abdominal cavity, and the difficulty in simultaneously achieving anti-adhesion and load-bearing repair in abdominal wall defect repair, this invention provides an injectable conductive anti-adhesion hydrogel, its preparation method, and its applications. This hydrogel utilizes dynamic covalent crosslinking and micellar physical crosslinking to construct a hybrid network, enabling rapid gelation and in-situ curing under catalytic promotion, while exhibiting excellent self-healing properties. The formulation can be adjusted to meet different needs for anti-adhesion and abdominal wall repair. Furthermore, it is loaded with active factors, possessing both conductive and antioxidant functions, effectively solving the challenges of existing technologies.

[0007] To achieve the above objectives, the present invention provides the following technical solution: an injectable conductive hydrogel, the raw materials of which include a phytic acid-doped gelatin-based conductive polymer containing hydrazide groups, an amphiphilic block copolymer containing aldehyde groups, and a catalyst, and the above three raw materials are mixed under body temperature and physiological conditions and then crosslinked in situ to form a hydrogel.

[0008] Furthermore, the final concentration ratio of the phytate-doped gelatin-based conductive polymer containing hydrazide groups to the final concentration of the aldehyde-containing amphiphilic block copolymer in the hydrogel is 1:2, and the concentration range of the aldehyde-containing amphiphilic block copolymer is 12.5 mg / mL to 200 mg / mL; the final concentration of the catalyst in the hydrogel is 0.786 mg / mL; and 0.2 mmol of phytate is added to 1 g of phytate-doped gelatin-based conductive polymer containing hydrazide groups.

[0009] Furthermore, the phytic acid-doped gelatin-based conductive polymer containing hydrazide groups is specifically a phytic acid-doped hydrazide-modified gelatin-polyaniline graft copolymer.

[0010] Furthermore, the amphiphilic block copolymer containing aldehyde groups is specifically aromatic aldehyde-modified Prönnick F127.

[0011] Furthermore, the hydrogel is loaded with a bioactive factor, which is basic fibroblast growth factor.

[0012] This invention provides a method for preparing an injectable conductive hydrogel, the specific steps of which are as follows: Using gelatin as a matrix, aniline is oxidatively polymerized and grafted onto gelatin chains under acidic conditions to obtain a gelatin-polyaniline copolymer; adipate dihydrazide is grafted onto the first solution via a carbodiimide coupling system to obtain hydrazideized precursor A, which is dissolved in water or PBS buffer to obtain the fourth solution by adding phytic acid-doped polyaniline to the first solution. Pluronic F127 was modified at the end group to introduce an aromatic aldehyde group to prepare precursor B, which was then dissolved in water or PBS buffer to obtain the second solution. The third solution is obtained by dissolving 4-aminophenylalanine in water or PBS buffer. The fourth solution was mixed with the second and third solutions and applied to the wound surface to form a conductive and anti-adhesion hydrogel in situ.

[0013] Furthermore, 0.2 mmol of phytic acid was added to each 1g of precursor A in the fourth solution; the concentration of precursor B in the second solution ranged from 12.5 mg / mL to 200 mg / mL; the final concentration ratio of precursor A to precursor B in the hydrogel was 1:2; and the final concentration of 4-aminophenylalanine in the hydrogel was 0.786 mg / mL.

[0014] Furthermore, the fourth solution is mixed with the second and third solutions in a synchronous injection manner according to a preset ratio at the user end to achieve in-situ gelation after mixing and injection.

[0015] Furthermore, the hydrogel is loaded with a bioactive factor, which is basic fibroblast growth factor.

[0016] The present invention also provides the application of the above-mentioned injectable conductive hydrogel or the injectable conductive hydrogel prepared by the above preparation method in postoperative anti-adhesion, wherein the amount of the amphiphilic block copolymer containing aldehyde group or precursor B is 12.5 mg / ml.

[0017] The present invention also provides the application of the above-mentioned injectable conductive hydrogel or the injectable conductive hydrogel prepared by the above preparation method in the repair of abdominal wall defects, wherein the amount of the amphiphilic block copolymer containing aldehyde group or precursor B is 150 mg / ml.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects: This invention provides an injectable conductive anti-adhesion hydrogel. The raw materials are a phytic acid-doped gelatin-based conductive polymer containing hydrazide groups, an aldehyde-containing amphiphilic block copolymer, and a catalyst. The hybrid network structure synergistically constructed by these three components combines the stability of chemical bonds with the flexibility of physical action, achieving a synergistic effect of multiple properties. The gelatin matrix possesses excellent tissue compatibility and biodegradability, ensuring biosafety for intraperitoneal application from the source. Its good hydrophilicity reduces the tendency of surface cell adhesion, naturally meeting the core requirements of the peritoneal anti-adhesion barrier. Phytic acid doping not only endows the hydrogel with stable conductive activity but also simultaneously enhances its antioxidant capacity, effectively scavenging reactive oxygen species (ROS), improving the postoperative inflammatory and oxidative stress microenvironment, and creating favorable conditions for tissue repair.

[0019] Compared to traditional anti-adhesion materials, this solution utilizes an in-situ cross-linking gel design under body temperature and physiological conditions, eliminating the need for additional complex equipment. It is suitable for minimally invasive procedures, easily filling and tightly adhering to irregular wounds within the abdominal cavity, fundamentally solving the problems of easy displacement and unstable coverage associated with existing materials. Simultaneously, the hybrid network structure endows the hydrogel with excellent self-healing properties and anti-disturbance capabilities, maintaining structural integrity and wound coverage stability even during dynamic traction of abdominal organs, preventing anti-adhesion failure due to material damage or displacement. The introduction of conductivity overcomes the limitations of traditional anti-adhesion materials that only achieve physical isolation, providing electroactive support for regulating cell behavior and promoting tissue repair, thus addressing the dual needs of anti-adhesion and tissue repair. The scientific combination of raw materials provides flexibility for performance control. Through the synergistic effect between components, a rapid gelation rate of the hydrogel under physiological conditions is ensured, while maintaining a balance between mechanical properties and toughness after gelation, enabling it to meet the mechanical challenges of the dynamic peritoneal environment. Furthermore, the combination of gelatin-based conductive polymers and amphiphilic block copolymers gives the hydrogel both good hydrophilicity and structural stability, avoiding the problems of excessive swelling or mechanical degradation of single materials in humid environments. This significantly improves the reliability of the material in the peritoneal cavity, laying the foundation for subsequent functional expansion and multi-scenario applications.

[0020] This invention specifies the optimal composition ratios for phytic acid doping (0.2 mmol phytic acid per 1g polymer), precursor concentration ratio (1:2), final catalyst concentration (0.786 mg / ml), and block copolymer concentration range (12.5 mg / mL to 200 mg / mL). This not only ensures stable performance in conductivity, self-healing ability, and mechanical properties but also provides a quantitative basis for subsequent adaptation to different application scenarios. Regarding raw material selection, the phytic acid-doped hydrazide-gelatin-polyaniline graft copolymer further enhances conductivity and structural stability. Aromatic aldehyde-modified Pluronic F127, as an amphiphilic block copolymer, optimizes the hydrophilic-hydrophobic balance of the hydrogel, improving its anti-swelling ability and wound adhesion in a moist peritoneal environment. Meanwhile, the design of loading basic fibroblast growth factor realizes the integration of anti-adhesion and repair-promoting functions, so that the hydrogel can not only inhibit adhesion through physical isolation and surface properties, but also promote tissue regeneration and healing through the regulation of active factors. This solves the shortcomings of traditional materials that can only passively prevent adhesion and cannot actively promote repair, and is especially suitable for scenarios such as abdominal wall defect repair that require both anti-adhesion and tissue regeneration.

[0021] The hydrogel preparation process of this invention uses gelatin as a matrix. A two-step reaction—aniline oxidative polymerization grafting and carbodiimide coupling grafting—is used to obtain hydrazide-substituted precursor A. Phytic acid doping then yields a fourth solution. The reaction conditions are mild and require no highly toxic reagents, ensuring the biosafety of the product and guaranteeing the stable bonding of the conductive components to the gelatin matrix, preventing the loss of conductivity. The terminal aromatic aldehyde modification process of Pluronic F127 is mature and reliable. The resulting precursor B and precursor A can form a highly efficient cross-linking system, providing a reaction basis for rapid in-situ gelation under physiological conditions. The third solution uses 4-aminophenylalanine as a catalyst, which has excellent biocompatibility and avoids the irritation to peritoneal tissues caused by traditional catalysts, further enhancing the clinical applicability of the hydrogel. The entire preparation process uses water or PBS buffer as solvent, eliminating the risk of organic solvent residue and meeting the purity requirements of medical materials. Furthermore, each precursor solution can be prepared in advance and stored stably, providing convenience for emergency clinical use and significantly reducing operational complexity.

[0022] The hydrogel preparation method of this invention effectively ensures the consistency of hydrogel performance and its adaptability to various scenarios. At the parameter level, the standardized preparation parameter system is established by clearly defining the phytic acid doping amount in the fourth solution, the concentration range of precursor B in the second solution, the final concentration ratio of precursors A and B, and the final catalyst concentration. This effectively avoids performance deviations in the hydrogel due to fluctuations in component ratios, ensuring the uniformity of product quality in large-scale production and providing crucial support for the industrialization of the technical solution. Regarding the application method, the design of simultaneously injecting the fourth solution with the second and third solutions in a preset ratio and mixing at the application end overcomes the limitations of traditional pre-formed gel materials that are difficult to adapt to complex wounds. It achieves a minimally invasive operation effect of mixing and injecting simultaneously, and forming gel upon injection. The injection volume can be flexibly adjusted according to the size and shape of the wound to ensure a close fit between the hydrogel and the wound. Meanwhile, the simultaneous injection method can precisely control the mixing reaction time, avoiding premature gelation that could clog instruments or delayed gelation that could lead to material displacement. This significantly improves the safety and convenience of clinical operations, making it particularly suitable for complex intra-abdominal minimally invasive surgery scenarios, and further enhancing the application advantages of hydrogels in dynamic intra-abdominal environments.

[0023] Furthermore, the hydrogel of this invention can precisely match the core needs of different clinical scenarios. Through differentiated dosage control, it achieves targeted adaptation of anti-adhesion performance and load-bearing repair performance, completely solving the industry pain point of difficulty in balancing anti-adhesion and load-bearing repair needs in abdominal wall defect repair. In postoperative anti-adhesion applications, using a dosage of 12.5 mg / ml of aldehyde-containing amphiphilic block copolymer (or precursor B) allows the hydrogel to form a soft and highly conformable network structure, focusing on enhancing anti-adhesion performance and biocompatibility. Through physical isolation, low cell adhesion, and ROS scavenging, it effectively inhibits postoperative wound tissue adhesion. Its biodegradability avoids secondary surgical removal, reducing patient suffering. In abdominal wall defect repair applications, increasing the dosage to 150 mg / ml significantly enhances the hydrogel's mechanical support performance and structural stability, enabling it to both exert an anti-adhesion effect and provide reliable mechanical support for the defect site, providing a stable support environment for abdominal wall tissue regeneration and healing.

[0024] This invention fully leverages the adjustable concentration of hydrogel components, enabling multi-purpose application and scenario adaptation. It eliminates the need to develop specialized materials for different needs, reducing clinical application costs. Simultaneously, the hydrogel's conductivity, self-healing ability, and potential for loading active factors can further promote tissue repair on top of its anti-adhesion properties. Particularly in abdominal wall defect repair, it provides mechanical support against abdominal pressure and organ traction, while its electroactivity and antioxidant properties improve the repair microenvironment, accelerating abdominal wall tissue healing. This creates an integrated application system of anti-adhesion, mechanical support, and repair promotion, offering significant clinical advantages over traditional single-function repair materials. Furthermore, all application schemes are based on injectable, in-situ gel-forming properties, adaptable to minimally invasive procedures, reducing surgical trauma and aligning with the trend towards minimally invasive surgery in modern medicine. Attached Figure Description

[0025] Figure 1 The proton nuclear magnetic resonance spectrum of the raw material (NMR) 1 HNMR spectrum).

[0026] Figure 2 The swelling curve of the hydrogel is shown.

[0027] Figure 3 The in vitro degradation curve of the hydrogel is shown.

[0028] Figure 4 This is the axial compressive stress-strain curve of the hydrogel.

[0029] Figure 5 The shear adhesion strength of the hydrogel to moist pigskin.

[0030] Figure 6 Strain scanning test (0-500% strain) for hydrogels.

[0031] Figure 7 This refers to the self-healing properties of hydrogels.

[0032] Figure 8 The CV cycle curve of the hydrogel is shown.

[0033] Figure 9 The probe's antioxidant properties are determined by the hydrogel.

[0034] Figure 10 This test assesses the reactive oxygen species scavenging performance of the hydrogel.

[0035] Figure 11 Cell viability of HUVECs cultured with different concentrations of hydrogel extract.

[0036] Figure 12 Images showing the live / dead staining of the hydrogel.

[0037] Figure 13 This is a test of the anti-cell adhesion of hydrogels.

[0038] Figure 14 Typical H&E stained sections of the injury site obtained on days 7 and 14 of a rat abdominal adhesion model.

[0039] Figure 15 Typical images of the lesion site obtained at week 2 and week 4 of the rat abdominal wall full-thickness defect model: (a) H&E staining; (b) Masson trichrome staining. Detailed Implementation

[0040] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0041] This invention provides a method for preparing a conductive anti-adhesion hydrogel, comprising the following steps: Preparation of the first solution: Using gelatin as the matrix, aniline was oxidatively polymerized under acidic conditions and grafted onto the gelatin molecular chain to obtain a gelatin-polyaniline copolymer GP with electroactive and antioxidant properties; subsequently, adipate dihydrazide (ADH) was grafted onto the GP molecular chain using a carbodiimide coupling system to introduce reactive hydrazide groups, resulting in hydrazide-modified gelatin-polyaniline graft copolymer GP-ADH (precursor A). Precursor A was then dissolved in an aqueous solution or PBS buffer to obtain the first solution. Preparation of the second solution: Pluronic F127 was modified at the end group to form an active intermediate. An aromatic aldehyde group was introduced to obtain aromatic aldehyde-modified Pluronic F127, namely PF127-CHO (precursor B). The precursor B was then dissolved in an aqueous solution or PBS buffer to obtain the second solution. Preparation of the third solution: Dissolve 4a-Phe (4-aminophenylalanine) in an aqueous solution or PBS buffer to obtain the third solution.

[0042] Phytic acid-doped polyaniline was added to the first solution to obtain the fourth solution. The fourth, second, and third solutions were mixed and applied to the wound surface, forming a conductive, anti-adhesion hydrogel in situ. The specific gelation mechanism of this hydrogel is as follows: Precursor A, precursor B, and precursor C were mixed. Under the catalysis of precursor C (4a-Phe), the hydrazide groups in precursor A and the aldehyde groups in precursor B condensed to form dynamic hydrazone covalent bonds, constructing a reversible chemical crosslinking main network. Simultaneously, the micelles formed by precursor B in the aqueous phase provided dispersion physics. Crosslinking points and energy dissipation units form a physicochemical synergistic hybrid network of dynamic covalent crosslinking main network and micellar physical micro-crosslinking. Based on this structure, the reversibility of dynamic acylhydrazone bonds and the rearrangement of micellar physical crosslinking points make the hydrogel thinner during shearing, which is conducive to injection. After shearing stops, the network is rapidly rebuilt, which is conducive to in-situ gelation and morphology maintenance. Moreover, when subjected to stretching, peristaltic friction or local rupture in vivo, the two rearrange and recombine synergistically, endowing the hydrogel with self-healing and fatigue resistance, and improving the structural stability of the capping layer in a humid dynamic environment.

[0043] Therefore, the hydrogel prepared by this invention possesses a unique dual-network structure: a physical cross-linking network composed of micelles formed by the self-assembly of PF127-CHO, and a dynamic chemical cross-linking network composed of dynamic acylhydrazone bonds formed by hydrazide groups and aldehyde groups. Based on this, it possesses injectability and rapid in-situ gelation capability. After being subjected to shearing or external force disturbance, it can achieve self-healing through the rearrangement of dynamic acylhydrazone bonds and the physical cross-linking points of the micelles. It also has electrical conductivity, antioxidant properties, and cell adhesion inhibition properties, and can form a stable covering layer on the surface of moist tissue. It is suitable for preparing medical materials, medical compositions, or medical devices for preventing or reducing postoperative abdominal adhesions.

[0044] Preferably, the concentration of PF127-CHO in the second solution ranges from 12.5 mg / mL to 200 mg / mL. More preferably, to balance swelling risk and tissue safety, the final concentration of PF127-CHO does not exceed 150 mg / mL. This invention achieves controllable adjustment of hydrogel formation time, swelling behavior, mechanical properties, and interfacial interactions by adjusting the final concentration of the aldehyde-containing amphiphilic block copolymer PF127-CHO.

[0045] Preferably, the final concentration ratio of GP-ADH to PF127-CHO in the hydrogel is 1:2 to balance the dynamic crosslinking formation efficiency and the intraoperative operability window.

[0046] Preferably, the pH values ​​of the first and second solutions are close to neutral to balance the requirements of reaction kinetics and biocompatibility.

[0047] Preferably, 0.2 mmol of phytic acid is added to each 1g of GP-ADH in the fourth solution; when the fourth solution is mixed with the second solution, the third solution is added to catalyze the process, which accelerates the formation of acylhydrazone bonds, thereby shortening the gelation time and improving gelation consistency and self-healing performance. The catalyst is 4a-Phe (4-aminophenylalanine), and its final concentration in the hydrogel is 0.786 mg / ml.

[0048] Preferably, the fourth solution and the second solution are mixed at the user end by synchronous injection with equal volume or a preset ratio. Preferably, a dual-chamber syringe or a proportional mixing device is used to achieve in-situ gelation after mixing and injection.

[0049] Preferably, the conductive component in the fourth solution and / or the hydrogel system formed therefrom is a polyaniline grafted segment, and the polyaniline is stabilized by phytic acid doping, thereby enhancing the hydrogel's ability to maintain electroactivity and its antioxidant properties in an aqueous environment.

[0050] Preferably, the conductive anti-adhesion hydrogel of the present invention is loaded with a bioactive factor, which is basic fibroblast growth factor rb-FGF. rb-FGF is pre-loaded by undergoing a reversible Schiff base reaction with the aldehyde group on PF127-CHO, and then cross-linked with GP-ADH to form a gel to achieve dynamic loading and continuous release, thereby promoting angiogenesis, collagen remodeling and myogenic differentiation, and improving the quality of regeneration and repair.

[0051] When the conductive anti-adhesion hydrogel of the present invention is used for postoperative anti-adhesion, a low-concentration formulation hydrogel of PF127-CHO 12.5 mg / ml is preferably used. This formulation hydrogel has the advantages of low modulus, low swelling and rapid degradation. It can cover the damaged surface of the serous membrane, form a short-term stable barrier and reduce frictional stimulation. At the same time, it reduces the ROS level by means of the antioxidant capacity of the conductive components and maintains the integrity of the coverage through the self-healing property of the dynamic network, thus inhibiting adhesion formation from both physical isolation and microenvironment regulation aspects.

[0052] When the conductive anti-adhesion hydrogel of the present invention is used for abdominal wall defect repair, a high-concentration formulation hydrogel of PF127-CHO 150mg / ml is preferred. This formulation hydrogel can provide load-bearing and deformation adaptability, and can be used as an adhesive or supporting hydrogel for in-situ fixation of the defect site. It has good biocompatibility, can promote the repair of defect tissue, and can simultaneously provide anti-adhesion coverage on the abdominal cavity side.

[0053] Example 1 This invention provides a conductive anti-adhesion hydrogel, the specific preparation steps of which are as follows: I. Preparation of acetylated gelatin-polyaniline graft copolymer GP-ADH (precursor A) (1) Polymer GP was prepared by using gelatin, aniline, and ammonium persulfate. The specific process is as follows: 2 g of gelatin was dissolved in 0.1 M HCl solution and dissolved at 50 °C for 1 h to form a 10 wt% gelatin solution. After cooling to room temperature, 82 μL of aniline and 201 mg of ammonium persulfate were added to the above solution, and the mixture was stirred at room temperature for 6 h. After the reaction was completed, the pH of the reaction mixture was adjusted to 7.0 with 1 M NaOH, and the product was precipitated in pre-cooled ethanol. The product was redissolved in deionized water and precipitated again in pre-cooled ethanol. This dissolution-precipitation process was repeated twice to purify the product. Finally, the product was dried in a vacuum oven for 2 days to obtain polymer GP.

[0054] (2) The hydrazide-modified polymer GP-ADH was prepared by polymer GP, adipic acid dihydrazide (ADH), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC), and 1-hydroxybenzotriazole (HOBt). The specific process is as follows: 1 g of polymer GP and 8 g of ADH were dissolved in 100 mL of deionized water and dissolved at 50 °C for 1 h. After cooling to room temperature, the pH of the solution was adjusted to 6.8 with 0.1 M NaOH and 0.1 M HCl. Pre-calculated amounts of EDC and HOBt were dissolved in DMSO / H₂O (1:1 volume ratio, 5 mL each) and added to the above mixture. The pH of the reaction system was maintained at 6.8 for 8 h, followed by a further 12 h of reaction. After the reaction was complete, the pH of the mixture was adjusted to 7.0, dialyzed against deionized water for 5 days, and lyophilized to obtain purified hydrazide-modified gelatin-polyaniline graft copolymer GP-ADH (precursor A). 1 1H NMR and FT-IR confirmed the successful grafting of PANI (characteristic peak at 8.11 ppm) and the modification of ADH (enhanced amide peak).

[0055] II. Preparation of Aromatic Aldehyde-Typonic F127, i.e., PF127-CHO (Precursor B) (1) The intermediate methanesulfonated F127 was prepared by polymer Pluronic F127, methanesulfonyl chloride and triethylamine. The specific process is as follows: 12.6 g of PF127 (Mn = 12600 Da) was placed in a flask and dried under vacuum at 80 °C for 12 h. Then, 120 mL of dry dichloromethane was added to dissolve it. The reaction mixture was placed in an ice-water bath, and 0.875 mL of dry triethylamine was added. Under nitrogen protection, 0.32 mL of methanesulfonyl chloride dissolved in 20 mL of dry dichloromethane was added dropwise over 30 min. The reaction was stirred continuously at room temperature for 24 h. Subsequently, 150 mL of water was added to the flask, and the mixture was extracted three times with 100 mL of dichloromethane. Finally, the organic phase was washed with 1 M hydrochloric acid solution (twice, 100 mL each time) and saturated brine (twice, 100 mL each time). NaSO4 was added to the organic layer to remove water, and the mixture was concentrated and cryogenically precipitated with diethyl ether. This purification was repeated three times to obtain methanesulfonic acid-terminated PF127 (PF-SO3).

[0056] (2) PF127-CHO, a benzaldehyde-terminated polymer, was prepared by using PF-SO3, 4-hydroxybenzaldehyde, and potassium carbonate. The specific process is as follows: All of the above-mentioned PF-SO3, 0.74 g of 4-hydroxybenzaldehyde, and 1.5 g of potassium carbonate were added to 100 mL of DMF. Under nitrogen protection, the mixture was stirred at 80 °C for 2 days. 150 mL of H2O was added to the flask, and the mixture was extracted three times with dichloromethane (100 mL each time). The organic layers were combined, washed twice with saturated brine (100 mL each time), dried over anhydrous Na2SO4, and concentrated to 50 mL. Finally, the product was precipitated with cold diethyl ether, and the purification was repeated three times to obtain aromatic aldehyde-modified Prönnicke F127, i.e., PF127-CHO (precursor B). NMR showed an aldehyde matrix peak at 9.85 ppm, confirming successful modification.

[0057] III. Preparation of Conductive Anti-Adhesion Hydrogels (1) Dissolve the polymer GP-ADH in PBS buffer (pH=6.8, 0.01 M) to prepare a first solution with a concentration of 30 wt%. Add 0.2 mmol of phytic acid-doped polyaniline to 1 g of GP-ADH to obtain a fourth solution. (2) Dissolve the polymer PF127-CHO in PBS buffer at 4°C to prepare a second solution with a concentration of 30wt%; (3) Dissolve the catalyst 4a-Phe (4-aminophenylalanine) in PBS buffer to obtain the third solution; (4) Different concentrations of PF127-CHO (12.5, 25, 50, 100, 150, 200 mg / mL) were set, the concentration of GP-ADH was controlled to be half that of PF127-CHO, and the final concentration of catalyst 4a-Phe in the hydrogel was 0.786 mg / mL. The fourth solution, the second solution and the third solution were mixed at 37°C, and a series of hydrogels were prepared by Schiff base reaction, named GPA / PF12.5 to GPA / PF200. The results showed that as the concentration increased, the gelation time was shortened from about 225 s to 3 s (Table 1), showing the adjustable gelation properties of the hydrogel. The excessively fast gelation speed of GPA / PF200 hydrogel was not conducive to injectable operation.

[0058] Table 1. Gel formation time data for hydrogels of different concentrations

[0059] Example 2 Figure 1 The substances obtained in Example 1 were analyzed. 1 ¹H NMR spectroscopy confirmed the successful synthesis of GP, GP-ADH, and PF127-CHO. The characteristic polyaniline peak at 8.11 ppm in GP confirmed successful PANI grafting; the significantly enhanced signal at 2.34 ppm further indicated successful ADH modification of GP. The aldehyde matrix peak at 9.85 ppm and the strong aromatic proton peaks at 7.79 and 7.00 ppm in PF127-CHO verified successful aldehyde alkylation.

[0060] Figure 2 The swelling behavior of GPA / PF hydrogels as a function of polymer concentration was investigated. The swelling behavior of the hydrogels was further analyzed by measuring the equilibrium swelling ratio (ESR) in PBS after 84 hours, revealing a clear concentration-dependent trend. GPA / PF100-150 hydrogels exhibited moderate and stable ESR values, while GPA / PF200 showed excessive swelling (>2.0), posing a risk of secondary tissue damage and was therefore excluded. In contrast, GPA / PF12.5 exhibited low shear modulus, high water content, and reduced swelling—properties that help reduce frictional stimulation on damaged membrane surfaces, highlighting its suitability as an anti-adhesion barrier.

[0061] Figure 3 The enzymatic degradation characteristics of GPA / PF hydrogels at different polymer concentrations were investigated. GPA / PF12.5 hydrogels rapidly degraded in PBS containing collagenase, forming a transient barrier, while GPA / PF150 degraded more slowly, indicating a longer residence time in vivo, which may help support abdominal wall tissue repair.

[0062] Figure 4 Axial compressive stress-strain curves of GPA / PF hydrogels with different polymer concentrations are shown. The compressive strength of the hydrogels increases significantly with increasing concentration (0.1-73.9 kPa).

[0063] Figure 5 The adhesion strength of the GPA / PF series hydrogels is shown. The adhesion strength of the hydrogels increases from 1.6 kPa to approximately 10.7 kPa with increasing concentration. This adhesion performance mainly comes from the Schiff base bonds formed between the aldehyde groups in PF127-CHO and the amine groups on the tissue surface. At the same time, the hydrogen bonds and electrostatic interactions between GP-ADH and the tissue also enhance the interfacial bonding strength.

[0064] Figure 6 Strain scanning tests (0-500% strain) were performed on the GPA / PF150 hydrogel. In the GPA / PF150 hydrogel, a crossover phenomenon between G′ and G″ was observed when the strain reached 251.4%, indicating that the network begins to collapse under extreme deformation conditions. This demonstrates the hydrogel's good self-healing potential.

[0065] Figure 7 The rheological self-healing behavior of GPA / PF150 hydrogel was evaluated using a stepped strain test. Under a large strain condition of 500%, G′ decreased from 33842 Pa to 400 Pa and G″>G′, indicating that the network was destroyed; when the strain recovered to 1%, G′ again exceeded G″, showing that the network was rapidly rebuilt, demonstrating its excellent self-healing ability.

[0066] Figure 8 The cyclic voltammetry curves for GPA / PF100 are shown. GPA / PF100 exhibits reversible redox peaks at approximately 0.3 V and 0.7 V, demonstrating the electrochemical reversibility of GPA.

[0067] Figure 9 To evaluate the antioxidant activity of GPA / PF hydrogel using the DCFH-DA probe via intracellular ROS detection, the H2O2 control group showed strong green fluorescence, while the fluorescence significantly decreased after the addition of GPA / PF hydrogel, indicating that the material has good intracellular ROS scavenging ability.

[0068] Figure 10 The variation of DPPH· free radical scavenging efficiency of GPA / PF hydrogel with hydrogel concentration. As the concentration of GPA / PF hydrogel increases, the antioxidant capacity gradually increases, indicating that free radicals are completely scavenged.

[0069] Figure 11The viability of HUVECs (Human Umbilical Vein Endothelial Cells) cultured with different concentrations of GPA / PF hydrogel extract was assessed. HUVECs were co-cultured with different concentrations of hydrogel extract (5, 10, and 20 mg / mL) for 24 h, with tissue culture plates (TCP) serving as the control group. Cell viability remained above 80% in all hydrogel extract treatment groups, comparable to the TCP group. GPA / PF hydrogel showed minimal cytotoxicity and excellent in vitro cell compatibility.

[0070] Figure 12 These are representative fluorescent LIVE / DEAD staining images of HUVECs cultured in GPA / PF hydrogel extract containing 20 mg / mL. HUVECs exposed to GPA / PF hydrogel maintained good polygonal morphology. Both the hydrogel group and the TCP group exhibited predominantly green fluorescence with only a small number of red dead cells. These results further demonstrate that GPA / PF hydrogel possesses excellent cell compatibility and is a promising candidate material for advanced wound dressings.

[0071] Figure 13 Anti-cell adhesion behavior of different concentrations of GPA / PF hydrogels. In the TCP control group, cells were abundant, well-spread, and exhibited strong cytoskeletal fluorescence, indicating good substrate adhesion ability. In contrast, all GPA / PF hydrogel groups significantly inhibited cell adhesion, with only extremely weak fluorescence signals observed. GPA / PF hydrogels exhibit significant anti-cell adhesion properties, effectively preventing the attachment and spread of endothelial cells on their surface.

[0072] The above characterization results show that the properties of GPA / PF hydrogels exhibit a significant polymer concentration dependence, and different concentration groups can be adapted to diverse application needs. In terms of mechanical properties, the GPA / PF150 group exhibits the highest compressive strength and excellent toughness, meeting the mechanical performance requirements during abdominal wall tissue repair; while the GPA / PF12.5 group, due to its lower shear modulus and softer texture, combined with its low expansion and high water content, is more suitable as a simple anti-adhesion barrier. Figure 4 Regarding its self-healing properties, rheological step strain tests confirmed that after the network structure was destroyed by a 500% large strain, the modulus of this hydrogel could be rapidly recovered, and G′ could exceed G″ to achieve network reconstruction, demonstrating excellent self-healing ability and the ability to cope with extreme deformation scenarios in application. Figure 7The antioxidant properties were fully validated by DPPH free radical scavenging assays and intracellular ROS probe detection. The polyaniline-containing GPA / PF hydrogel effectively scavenged free radicals, significantly reduced intracellular ROS levels, and effectively protected cells from oxidative stress damage. Figure 9-10 Furthermore, this series of hydrogels exhibits both good cell compatibility and significant anti-cell adhesion properties, and the degradation rate can be precisely controlled in some concentration groups, further demonstrating that GPA / PF hydrogels have broad application prospects and potential value as advanced wound dressings and abdominal wall tissue repair materials.

[0073] Example 3 1. H&E staining in a rat model of intraperitoneal adhesions Groups: blank control group (physiological saline), commercial product group (hyaluronic acid dressing gel), GT-ADH / PF-CHO12.5 group (non-conductive component control GTA / PF12.5), GP-ADH / PF-CHO12.5 group (the present invention GPA / PF12.5).

[0074] Figure 14 These are typical H&E stained sections of the injury site obtained on postoperative days 7 and 14. Combined with the staining results, it is evident that on postoperative day 7, both the control group and the commercial hydrogel group showed extensive adhesion formation, accompanied by complete loss of the anatomical boundary between the cecum and the abdominal wall. Disordered clusters of fibroblasts were densely aggregated, with significant inflammatory cell infiltration and marked fibrotic tissue hyperplasia. On postoperative day 14, the fibrous adhesions significantly thickened and expanded, completely covering the injury site. Simultaneously, the cecal smooth muscle layer ruptured and pathologically fused with the abdominal wall muscle tissue. Large areas of connective tissue hyperplasia and collagen deposition were also clearly visible within the adhesion area.

[0075] Conversely, animals treated with GTA / PF12.5 or GPA / PF12.5 (the present invention) hydrogel showed no obvious adhesions, and the structural layers were clearly distinguishable and well preserved on postoperative days 7 and 14. Notably, the GPA / PF12.5 (the present invention) hydrogel promoted the orderly and continuous regeneration of serous mesothelial cells, a key prerequisite for restoring peritoneal lubrication and fibrinolytic function. Compared with other groups, this group showed significantly reduced inflammatory cell infiltration and collagen deposition, while the commercial hydrogel group still exhibited significant and persistent fibrosis.

[0076] Repair effect: In the experiment of low modulus formulation (GTA / PF12.5), the GPA / PF12.5 hydrogel of the present invention can effectively inhibit postoperative peritoneal adhesions and promote the synergistic structural repair of the damaged cecum and abdominal wall, thus highlighting its great potential as a highly effective anti-adhesion treatment.

[0077] 2. H&E staining and Masson's trichrome staining in a rat model of full-thickness abdominal wall defect Groups: blank control group (physiological saline), commercial product group (hyaluronic acid dressing gel), GT-ADH / PF-CHO150 group (non-conductive component control GTA / PF150), GP-ADH / PF-CHO150 group (GPA / PF150 of this invention), GP-ADH / PF-CHO150+FGF group (GPA / PF150+FGF of this invention).

[0078] Figure 15 Typical images of sections of the injury site obtained 2 and 4 weeks after surgery: (a) H&E staining; (b) Masson trichrome staining. H&E staining showed that after 2 weeks of application, the GP-ADH / PF-CHO150 group (in this invention) and the GP-ADH / PF-CHO150+FGF group (in this invention) had a lighter blue-purple color at the wound site than the other three groups, indicating a lower inflammatory response; after 4 weeks, the GP-ADH / PF-CHO150+FGF group (in this invention) showed a "lamellar"-like structure, proving that the collagen was highly mature, indicating that FGF enhanced the repair-promoting properties of the hydrogel.

[0079] Since orderly collagen remodeling is crucial for restoring the mechanical integrity and function of the abdominal wall, Masson's trichrome staining method was used to assess collagen deposition. Staining results showed that the blank group, commercial control group, and GTA / PF150 group exhibited sparse, loose, and disordered collagen structures, while dense and regularly arranged collagen fibers were observed in the GPA / PF150 group and the GPA / PF150+FGF group. Notably, after 4 weeks of application, the GP-ADH / PF-CHO150+FGF group (the present invention) showed the best repair quality, with dense, parallel collagen bundles in the newly healed area, closely resembling normal dermal structure. Its collagen remodeling was the most significant and spatially continuous, thus providing strong histological evidence for enhancing and accelerating abdominal wall regeneration.

[0080] The GP-ADH / PF127-CHO hydrogel prepared in this invention has tunable mechanical properties through physical-chemical dual cross-linking. Its unique conductivity and antioxidant properties enable it to actively regulate the inflammatory microenvironment and promote tissue repair while preventing postoperative adhesions. It is a bifunctional biomaterial with great clinical translation potential.

Claims

1. An injectable conductive hydrogel, characterized in that, The raw materials include a phytic acid-doped gelatin-based conductive polymer containing hydrazide groups, an amphiphilic block copolymer containing aldehyde groups, and a catalyst. The three raw materials are mixed under body temperature and physiological conditions and then crosslinked in situ to form a hydrogel.

2. The injectable conductive hydrogel according to claim 1, characterized in that, The final concentration ratio of the phytate-doped gelatin-based conductive polymer containing hydrazide groups to the final concentration of the aldehyde-containing amphiphilic block copolymer in the hydrogel was 1:2, and the concentration range of the aldehyde-containing amphiphilic block copolymer was 12.5 mg / mL to 200 mg / mL; the final concentration of the catalyst in the hydrogel was 0.786 mg / mL; 0.2 mmol of phytate was added to 1 g of phytate-doped gelatin-based conductive polymer containing hydrazide groups.

3. The injectable conductive hydrogel according to claim 1, characterized in that, The phytic acid-doped gelatin-based conductive polymer containing hydrazide groups is specifically a phytic acid-doped hydrazide-modified gelatin-polyaniline graft copolymer.

4. The injectable conductive hydrogel according to claim 1, characterized in that, The amphiphilic block copolymer containing aldehyde groups is specifically aromatic aldehyde-modified Prönnick F127.

5. The injectable conductive hydrogel according to claim 1, characterized in that, The hydrogel is loaded with a bioactive factor, which is basic fibroblast growth factor.

6. A method for preparing an injectable conductive hydrogel, characterized in that, The specific steps are as follows: Using gelatin as a matrix, aniline is oxidatively polymerized and grafted onto gelatin chains under acidic conditions to obtain a gelatin-polyaniline copolymer; adipate dihydrazide is grafted onto the first solution via a carbodiimide coupling system to obtain hydrazideized precursor A, which is dissolved in water or PBS buffer to obtain the fourth solution by adding phytic acid-doped polyaniline to the first solution. Pluronic F127 was modified at the end group to introduce an aromatic aldehyde group to prepare precursor B, which was then dissolved in water or PBS buffer to obtain the second solution. The third solution is obtained by dissolving 4-aminophenylalanine in water or PBS buffer. The fourth solution is mixed with the second and third solutions in a preset ratio and applied to the wound surface via synchronous injection at the application end to form a conductive and anti-adhesion hydrogel in situ.

7. The method for preparing an injectable conductive hydrogel according to claim 6, characterized in that, In the fourth solution, 0.2 mmol of phytic acid was added for every 1g of precursor A; in the second solution, the concentration of precursor B ranged from 12.5 mg / mL to 200 mg / mL; the final concentration ratio of precursor A to precursor B in the hydrogel was 1:2; and the final concentration of 4-aminophenylalanine in the hydrogel was 0.786 mg / mL.

8. The method for preparing an injectable conductive hydrogel according to claim 6, characterized in that, The hydrogel is loaded with a bioactive factor, which is basic fibroblast growth factor.

9. The injectable conductive hydrogel according to any one of claims 1 to 5 or the injectable conductive hydrogel prepared by the preparation method according to any one of claims 6 to 8 is used in postoperative anti-adhesion, characterized in that, The amount of amphiphilic block copolymer containing aldehyde groups or precursor B is 12.5 mg / ml.

10. The injectable conductive hydrogel according to any one of claims 1 to 5 or the injectable conductive hydrogel prepared by the preparation method according to any one of claims 6 to 8 is used in the repair of abdominal wall defects, characterized in that, The amount of amphiphilic block copolymer containing aldehyde groups or precursor B is 150 mg / ml.

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