A self-reinforcing osteogenic adhesive based on an alkaline microenvironment, its preparation method and application

Abstract

This invention relates to a self-reinforcing osteogenic adhesive based on an alkaline microenvironment, its preparation method, and its applications. It addresses the challenges of existing bone adhesives in simultaneously utilizing the osteogenic microenvironment for material self-reinforcement and in simultaneously achieving wet-state adhesion stability, cohesive toughness, and biodegradability. The invention involves uniformly mixing cycloenol acetal monomer, vinyl comonomer, self-reinforcing functional monomer, alkaline inorganic nanofiller, and a crosslinking agent. An oxidant and a reducing agent are then added and mixed uniformly to obtain a precursor mixture. This mixture is then subjected to in-situ ring-opening polymerization and cured to obtain a self-reinforcing osteogenic adhesive based on an alkaline microenvironment. The adhesive provided by this invention exhibits excellent biodegradability and achieves a synergistic improvement in the material's bulk mechanical stability and bone interface fixation ability during the wet functional period. It can be applied in the field of medical adhesives, providing a material platform with both adhesive fixation and osteogenic induction potential for bone defect repair and bone tissue regeneration.

Description

Technical Field

[0001] This invention relates to the field of biomedical materials technology, specifically to a self-reinforcing osteogenic adhesive based on an alkaline microenvironment, its preparation method, and its application. Background Technology

[0002] Fractures and bone defects are common clinical problems in trauma and orthopedic diseases. Traditional metal internal fixation devices such as screws and plates remain important means of fracture fixation, but they have drawbacks in fixing comminuted fractures, complex and irregular bone fracture surfaces, or small bone fragments, including complex operation, local stress concentration, easy slippage of bone fragments, and the need for secondary surgery to remove them in some patients. Biodegradable bone adhesives can provide temporary fixation during bone healing and gradually degrade as tissue repair progresses, reducing the risk of permanent foreign body residue and secondary removal. They show promising application prospects in comminuted fracture reduction, bone defect filling, and fixation of bone tissue interfaces.

[0003] In orthopedic applications, existing medical adhesives, such as synthetic adhesives represented by cyanoacrylates, possess excellent immediate bond strength. However, their main chains are primarily composed of carbon-carbon bonds, resulting in extremely long degradation cycles. After implantation, they can easily form physical barriers at bone defects or fracture interfaces, hindering the reconstruction and replacement of new bone tissue. While bio-based adhesives, such as fibrin glue, exhibit good biocompatibility and biodegradability, their intrinsic cohesive strength and interfacial adhesion are limited, making it difficult to meet the mechanical support requirements for bone fixation. Furthermore, current medical adhesives all face severe water plasticization under physiologically moist conditions: water molecules penetrating into the matrix weaken the interactions between polymer chains, leading to uncontrolled swelling and softening of the material. This causes a precipitous decline in mechanical strength before bone regeneration is complete, ultimately resulting in internal fixation failure.

[0004] To balance adhesive strength and biodegradability, Chinese invention patent CN116407668A discloses a fast-curing and biodegradable high-strength bone adhesive. This adhesive achieves a mechanically interlocked structure with the tissue surface through in-situ free radical ring-opening polymerization, and introduces a polyester structure into the polymer backbone using cycloenone acetal monomers, thereby endowing the material with biodegradability. This approach improves the initial adhesive performance of the biodegradable bone adhesive; however, in wet environments, moisture intrusion still weakens the material's network stability and interfacial adhesive strength, resulting in a decline in wet mechanical properties. To address these issues, Chinese invention patent CN121360285A discloses a self-reinforcing hydrogel based on in-situ in-situ initiated double crosslinking. This hydrogel utilizes enzyme catalysis to generate free radicals and drive secondary crosslinking to improve material strength. However, the reinforcement process of this system heavily depends on the concentration of the endogenous substrate, limiting and uncontrolling the reinforcement rate and degree. Furthermore, for fracture fixation, the inherent mechanical modulus and load-bearing capacity of the hydrogel matrix are low, making it difficult to meet the mechanical performance requirements for fracture fixation.

[0005] In addition to necessary mechanical fixation, bone adhesives should also possess bioactivity that promotes bone repair during bone repair. Inorganic nanoparticles can provide favorable conditions for bone tissue regeneration by releasing active ions, regulating the local microenvironment, and promoting osteogenic differentiation. Chinese invention patent CN117139118A discloses a coating with high osteointegration capacity, which constructs a local alkaline microenvironment through a polyMg-O-coated hydroxyapatite array to promote bone tissue healing and regeneration. This type of technology can improve the osteointegration capacity of the implant surface, but its main purpose in constructing an alkaline microenvironment is to regulate cell behavior and promote osteogenic repair. The alkaline environment itself does not participate in the construction and reinforcement of the adhesive network structure, and cannot simultaneously improve the interfacial bonding stability and bulk mechanical properties of the material in a humid environment. At the same time, this type of coating usually exists in the form of a prefabricated structure, and the preparation process is complex, making it difficult to meet the requirements of in-situ filling, immediate bonding, and multi-fragment fixation of irregular bone fracture surfaces in comminuted fractures. In addition, although existing absorbable bone cements can form absorbable support materials through in-situ polymerization of cycloalkenone acetal monomers and introduce inorganic nanomaterials to improve bone repair performance, they are mainly used for bone defect filling and mechanical support. They are difficult to form stable adhesion at the wet bone interface and cannot simultaneously improve the interface fixation ability and the mechanical properties of the material itself during the bone healing process.

[0006] Therefore, how to achieve rapid and effective adhesion in a wet environment and maintain adhesive stability, cohesive toughness, and biodegradability during the bone healing functional period; and how to ensure that the bone repair-related microenvironment can not only promote osteogenic regeneration but also participate in the continuous reinforcement of the material network to achieve a synergistic effect of improved mechanical properties and bone regeneration promotion, are important technical problems that need to be solved in the development of self-reinforcing osteogenic biodegradable adhesives. Summary of the Invention

[0007] To address the challenges of existing bone adhesives in simultaneously utilizing the osteogenic microenvironment for material self-reinforcement, and in simultaneously achieving wet-state bonding stability, cohesive toughness, and biodegradability, this invention proposes a self-reinforcing osteogenic adhesive based on an alkaline microenvironment, its preparation method, and its application. The technical solution of this invention is as follows: A self-reinforcing osteogenic adhesive based on an alkaline microenvironment comprises the following components: Cycloenol acetal monomer, vinyl comonomer, self-reinforcing functional monomer, crosslinking agent and alkaline inorganic nanofiller; The self-reinforcing functional monomer is any one or at least a combination of two of the following: 3-(methacryloyloxy)propyltrimethoxysilane, 3-(acryloyloxy)propyltrimethoxysilane, 3-(methacryloyloxy)propyltriethoxysilane (TESPMA), 3-(acryloyloxy)propyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, 3-isopropenyl-α,α-dimethylbenzyl isocyanate, methacryloyloxyethyl isocyanate, acryloyloxyethyl isocyanate, methacryloyl isocyanate, and acryloyl isocyanate. The alkaline inorganic nanofiller is any one or at least a combination of two of the following: nano magnesium oxide, nano calcium oxide, nano zinc oxide, nano magnesium hydroxide, nano calcium hydroxide, nano hydroxyapatite, and nano bioactive glass.

[0008] Further, the cycloenone acetal monomer is any one or a combination of at least two of the following: 2-methylene-1,3-dioxane-1,3-dioxane-heptane (MDO), 4,7-dimethyl-2-methylene-1,3-dioxane-heptane (DMMDO), 5,6-benzo-2-methylene-1,3-dioxane-heptane, 4-methylene-2-phenyl-1,3-dioxane-pentane, 2-methylene-1,3-dioxane-pentane, and 4,4-dimethyl-2-methylene-1,3-dioxane-pentane. The vinyl comonomer is any one or at least a combination of two of the following: hydroxyethyl methacrylate (HEMA), hydroxyethyl acrylate, hydroxypropyl methacrylate (HPMA), hydroxypropyl acrylate, 4-hydroxybutyl methacrylate, 4-hydroxybutyl acrylate, glycidyl methacrylate, glycidyl acrylate, methacrylamide, acrylamide, N-(2-hydroxyethyl)methacrylamide, N-(2-hydroxyethyl)acrylamide, N,N-dimethylmethacrylamide, N,N-dimethylacrylamide, polyethylene glycol monomethacrylate, polyethylene glycol monoacrylate, and N-vinylpyrrolidone; the molar ratio of the cycloenol acetal monomer, the vinyl comonomer, and the self-reinforcing functional monomer is 0.1~10:1:0.05~1; preferably 0.2~5:1:0.1~0.5, more preferably 0.5~2:1:0.167~0.25.

[0009] Further, the crosslinking agent is any one or at least a combination of two of the following: ethylene glycol dimethacrylate, N,N'-methylenebisacrylamide, diethylene glycol dimethacrylate, diethylene glycol diacrylate, polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, trimethylolpropane trimethacrylate, and trimethylolpropane triacrylate; the molar fraction of the crosslinking agent in the total molar fraction of the cycloenone acetal monomer, vinyl comonomer, and self-reinforcing functional monomer is 0.2 mol% to 30 mol%, preferably 0.5 mol% to 10 mol; more preferably 1 mol% to 5 mol.

[0010] Furthermore, the alkaline inorganic nanofiller accounts for 0.2% to 15% of the total mass of the cycloenone acetal monomer, vinyl comonomer, and self-reinforcing functional monomer, preferably 0.5% to 10%; more preferably 1% to 5%.

[0011] Furthermore, the self-reinforcing osteogenic adhesive based on an alkaline microenvironment also includes a redox initiation system, which is obtained by mixing an oxidant and a reducing agent. The molar ratio of the oxidant to the reducing agent is 1:0.2~5, preferably 1:0.5~2; more preferably 1:0.8~1.2. The redox initiation system accounts for 0.1mol%~5mol% of the molar fraction of the cycloenone acetal monomer, vinyl comonomer, and self-reinforcing functional monomer, preferably 0.5mol%~2mol%, more preferably 0.8mol%~1.2mol%.

[0012] A method for preparing the above-mentioned self-reinforcing osteogenic adhesive based on an alkaline microenvironment includes the following preparation steps: The cycloenone acetal monomer, vinyl comonomer, self-reinforcing functional monomer, alkaline inorganic nanofiller and crosslinking agent are mixed evenly, and then an oxidant and a reducing agent are added and mixed evenly to obtain a precursor mixture. In-situ ring-opening polymerization reaction is carried out and cured to obtain a self-reinforcing osteogenic adhesive based on an alkaline microenvironment.

[0013] Furthermore, the in-situ ring-opening polymerization reaction takes 1 to 10 minutes and is carried out at a temperature of 20°C to 37°C.

[0014] An application of the above-mentioned self-reinforcing osteogenic adhesive based on an alkaline microenvironment is applied in the field of medical adhesives.

[0015] Furthermore, in the field of medical adhesive materials for fracture repair and bone defect treatment, the application steps of the self-reinforcing osteogenic adhesive based on an alkaline microenvironment are as follows: The precursor mixture is applied to the bone bonding interface, where an in-situ ring-opening polymerization reaction occurs, followed by curing to complete the bone bonding.

[0016] Furthermore, the precursor mixture is applied to the bonding interface by in-situ coating, injection, or filling; the bone bonding interface is a flat surface or any irregular cross-section.

[0017] Compared with existing technologies, this invention solves the problems that existing bone adhesives cannot simultaneously participate in material self-reinforcement by utilizing the osteogenic microenvironment, and cannot simultaneously ensure wet bonding stability, cohesive toughness, and biodegradability. Specifically, the beneficial effects are as follows: 1. This invention proposes an osteogenic bonding strategy based on self-reinforcing alkaline microenvironment. A biodegradable bone adhesive network is constructed using cycloenol acetal monomers and vinyl comonomers, and self-reinforcing functional monomers and alkaline inorganic nanofillers are introduced. Nano-magnesium oxide forms a locally alkaline microenvironment in a humid environment, promoting the hydrolysis and condensation reaction of silane groups in the self-reinforcing functional monomers. This leads to a secondary cross-linking reinforcement structure between the adhesive bulk network and the bone tissue bonding interface, thereby improving the material's network stability, cohesive strength, and mechanical support capacity in a humid environment. Through the synergistic effect of the alkaline inorganic nanofillers and the self-reinforcing functional monomers, the adhesive can further form a siloxane cross-linked network in a hydrated environment, increasing the polymer network cross-linking density and restricting chain segment movement, effectively compensating for the swelling and plasticizing effects of moisture on the material. This invention significantly improves the bulk mechanical properties after hydration while maintaining effective bone tissue bonding capacity. The tensile strength after hydration reaches 16.1 MPa, and the Young's modulus after hydration reaches 300 MPa, achieving a synergistic improvement in the material's bulk mechanical stability and bone interface fixation capacity during the humid functional period.

[0018] 2. This invention introduces hydrolyzable ester bonds into the polymer backbone through the free radical ring-opening polymerization of cycloenol acetal monomers, enabling the self-reinforcing osteogenic adhesive based on an alkaline microenvironment to possess post-functional degradability. Compared with commercially available cyanoacrylate-based medical adhesives like Vetbond, the material of this invention exhibits significant mass loss under alkaline accelerated degradation conditions, avoiding the foreign matter risk associated with long-term residues of non-degradable adhesives. Simultaneously, the introduction of self-reinforcing functional monomers and alkaline inorganic nanofillers does not block the hydrolysis of ester bonds in the polymer backbone; instead, it regulates water penetration and network disintegration processes through a siloxane self-reinforcing network and inorganic filler phases, making the material's degradation behavior more controlled. The accelerated degradation rate of this invention within 7 days can be controlled within the range of 25% to 40%. By adjusting the composition ratio of cycloenol acetal monomers, vinyl comonomers, self-reinforcing functional monomers, and alkaline inorganic nanofillers, structural stability can be maintained during the bone tissue fixation functional period, and gradual degradation can occur after the functional period.

[0019] 3. This invention utilizes alkaline inorganic nanofillers to construct an osteogenic-friendly local microenvironment, achieving synergistic effects of adhesion fixation, mechanical enhancement, and osteogenic regulation. Nano-magnesium oxide hydrates in a moist environment to form a locally weakly alkaline environment and releases magnesium ions. This microenvironment provides favorable conditions for osteoblast adhesion, proliferation, and early osteogenic differentiation. Simultaneously, the weakly alkaline environment promotes the hydrolysis and condensation of silane groups in the self-reinforcing functional monomers, maintaining a stable network structure in cell culture or body fluid simulation environments. This invention significantly increases the alkaline phosphatase activity of osteoblast MC3T3-E1 cells on the material surface, with an ALP activity as high as 0.89. This indicates that this invention not only meets the requirements for bone tissue interface adhesion and wet mechanical support but also participates in osteogenic regulation through an alkaline microenvironment, providing a material platform with both adhesion fixation and osteogenic induction potential for bone defect repair and bone tissue regeneration. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of shear bonding test and tensile mechanical strength test of self-reinforcing osteogenic adhesive based on alkaline microenvironment; Figure 2 Figure 1 shows the in vitro bone bonding test results of a self-reinforcing osteogenic adhesive based on an alkaline microenvironment. Figure 3 The figure shows the tensile mechanical strength test results of the self-reinforcing osteogenic adhesive based on the alkaline microenvironment. Figure 4 Figure 1 shows the in vitro accelerated degradation test results of the self-reinforcing osteogenic adhesive based on an alkaline microenvironment. Figure 5 The results show the ALP activity of cells on the surface of self-reinforcing osteogenic adhesives based on an alkaline microenvironment. Detailed Implementation

[0021] To make the technical solutions of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that the following embodiments are only used to better understand the technical solutions of the present invention and should not be construed as limiting the present invention.

[0022] Example 1. 0.1 g MDO (0.88 mmol), 0.12 g HEMA (0.88 mmol), 0.037 g TESPMA (0.13 mmol) and 5 mg nano magnesium oxide were mixed evenly. 0.018 mmol ethylene glycol dimethacrylate (1 mol% of the total monomer molar amount) was added and mixed evenly at room temperature. 0.018 mmol BPO (1 mol% of the total monomer molar amount) was then added and dissolved completely. 0.018 mmol DMPT (1 mol% of the total monomer molar amount) was then added and mixed evenly to obtain a precursor mixture. The mixture was subjected to in-situ ring-opening polymerization at 37 °C for 5 min and cured to obtain a self-reinforcing osteogenic adhesive based on an alkaline microenvironment.

[0023] Example 2. The difference between this embodiment and Example 1 is that the vinyl comonomer is replaced with HPMA, and the amount of HPMA is adjusted to 0.13 g (0.88 mmol). The remaining preparation steps and conditions are the same as in Example 1, and the self-reinforcing osteogenic adhesive based on the alkaline microenvironment is obtained after curing.

[0024] Example 3. The difference between this embodiment and Example 1 is that the cycloenone acetal monomer is replaced with 0.1 g (0.70 mmol) of DMMDO; the amount of HEMA is adjusted to 0.09 g (0.70 mmol), and the amount of TESPMA is adjusted to 0.029 g (0.10 mmol); the remaining preparation steps and conditions are the same as in Example 1, and the self-reinforcing osteogenic adhesive based on the alkaline microenvironment is obtained after curing.

[0025] Example 4. The difference between this embodiment and Example 1 is that the cycloenone acetal monomer is replaced with 0.1 g (0.70 mmol) of DMMDO; the vinyl comonomer is replaced with HPMA, and the amount of HPMA is adjusted to 0.10 g (0.70 mmol), and the amount of TESPMA is 0.029 g (0.10 mmol); the remaining preparation steps and conditions are the same as in Example 1, and the self-reinforcing osteogenic adhesive based on the alkaline microenvironment is obtained after curing.

[0026] Comparative Example 1. Vetbond, a commercially available cyanoacrylate medical adhesive from 3M, has 2-cyanoacrylate n-butyl ester as its core chemical component.

[0027] Comparative Example 2. The difference between this comparative example and Example 3 is that no self-reinforcing functional monomers and alkaline inorganic nanofillers are added. The remaining preparation steps and conditions are the same as in Example 1, and the adhesive is cured to obtain the adhesive.

[0028] (a) Shear bond test and tensile mechanical strength test: The in vitro bone tissue shear bond strength of the adhesives prepared in Examples 1-4 and Comparative Examples 1-2 was tested according to GB / T 7124-2008 standard. Bovine bones were cut into regular plate-shaped strips, each 10 cm × 2.5 cm in length and width, and 0.2 cm in thickness. The precursor mixtures prepared in Examples 1-4 and Comparative Example 2 before curing, along with the adhesive provided in Comparative Example 1, were applied to the bonding area of ​​the bone strips. Two bone strips were then bonded according to… Figure 1 (a) The two bone strips were overlapped and bonded as shown in the diagram, with the adhesive positioned between the overlapping interfaces. The effective bonding area of ​​the bone bond was 2.5 cm × 1.0 cm. After the bone bond was placed at room temperature for 1 h, a shear tensile test was performed using a universal testing machine (LD-5 model, LLOYD, sensor range 2.5 kN, tensile rate 5 mm / min). The maximum load force at which the bone bond fractured or the interface failed was recorded, and the shear bond strength was calculated using the following formula: Shear bond strength = Maximum load force / Effective bonding area.

[0029] The in vitro bone adhesion test results of Examples 1-4 and Comparative Examples 1-2 are as follows: Figure 2 As shown in the figure, Examples 1-4 all exhibited shear bond strengths higher than 0.7 MPa, meeting the clinical requirements for wet bone bond shear strength (≥200 kPa), indicating that the adhesives formed by different monomer combinations of the present invention can form effective bonding and fixation at the bone tissue interface. Examples 1-4 respectively used MDO / HEMA, MDO / HPMA, DMMDO / HEMA, and DMMDO / HPMA to construct degradable polymer networks, and introduced self-reinforcing functional monomers and alkaline inorganic nanofillers to form an alkaline microenvironment self-reinforcing system. Among them, the cycloenone acetal monomer introduces degradable ester bonds into the polymer backbone through free radical ring-opening polymerization, providing a degradable structural basis for the material; HEMA or HPMA, as vinyl comonomers, can regulate the wetting and penetration behavior of the precursor at the bone tissue interface and the polymer network structure after curing; the self-reinforcing functional monomer can participate in copolymerization and provide subsequent interfacial reaction sites; the alkaline inorganic nanofiller can construct a local alkaline microenvironment, promoting the further enhancement of the adhesive body and the bone tissue interface. Therefore, Examples 1-4 can all form a biodegradable adhesive system with bone tissue bonding ability, which also shows that the present invention is adaptable to the combination of cycloenone acetal monomer and vinyl comonomer.

[0030] Comparative Example 1, the commercially available cyanoacrylate-based medical adhesive Vetbond, exhibited comparable adhesive strength to Examples 1 and 3. Comparative Example 2, without the introduction of the self-reinforcing functional monomer TESPMA and alkaline inorganic nanofillers, showed a shear bond strength of 1.4 MPa, indicating that the basic biodegradable polymer network formed solely by the cycloenone acetal monomer and vinyl comonomer was sufficient to provide bone tissue adhesion. However, due to the lack of TESPMA and nano-magnesium oxide in Comparative Example 2, the system lacked the basic mechanisms for alkaline microenvironment-induced silane hydrolysis condensation, self-reinforcing network construction, and bone interface mineralization regulation. Therefore, the differences between Comparative Examples 1, 2, and the examples are not only reflected in the initial shear bond strength but also require further evaluation through subsequent wet stability, bulk mechanical properties, and osteogenic-related tests. This comparative example provides a basis for subsequent explanations of the contribution of the alkaline microenvironment self-reinforcing system to the overall material performance.

[0031] To further evaluate the effect of the alkaline microenvironment self-reinforcing system on the bulk mechanical properties and post-hydration mechanical stability of the materials, tensile mechanical property tests were conducted on the adhesives prepared in Examples 1-4 and Comparative Example 2 according to ASTM D638 standard. The precursor mixtures of Examples 1-4 and Comparative Example 2 before curing were injected into... Figure 1 (b) The dumbbell-shaped mold was placed at room temperature for 1 h to complete in-situ polymerization, cross-linking, and curing. Tensile testing was then performed using a LLOYD LD-5 universal testing machine with a sensor range of 500 N and a tensile rate of 50 mm / min. The stress-strain curve was calculated and plotted based on the load-displacement curve obtained from the test. The tensile strength was calculated by dividing the maximum load by the cross-sectional area at the narrow neck of the specimen. Young's modulus was calculated using the slope of the initial linear region of the stress-strain curve. Simultaneously, the cured dumbbell-shaped specimen was completely immersed in water and placed at 37°C for 7 days. The tensile strength and Young's modulus after 7 days of hydration were then tested and calculated using the same method.

[0032] The above test results are as follows Figure 3As shown in the figure, after 7 days of hydration, the tensile strength and Young's modulus of Examples 1-4 were significantly improved compared to the corresponding initial samples (the tensile strength of Example 3 reached 16.1 MPa, and the Young's modulus reached 300 MPa). This indicates that the self-reinforcing osteogenic adhesive based on an alkaline microenvironment provided by the present invention did not experience bulk mechanical degradation due to the entry of water in the hydration environment, but instead formed a water-induced reinforcing effect. This is mainly because Examples 1-4 all introduced the self-reinforcing functional monomer TESPMA and alkaline inorganic nanofillers. Nano-magnesium oxide can provide a local alkaline microenvironment in the hydration environment, promoting the hydrolysis and condensation reaction of the alkoxysilane groups in TESPMA, and forming a further siloxane cross-linked structure inside the polymer network. This alkaline microenvironment-induced secondary cross-linking can increase the network cross-linking density, restrict chain segment movement, and partially offset the plasticizing effect of water on the polymer network. Therefore, the material still exhibits a simultaneous increase in tensile strength and Young's modulus after hydration.

[0033] In contrast, Comparative Example 2, which did not introduce the self-reinforcing functional monomer TESPMA and alkaline inorganic nanofillers, although its initial tensile strength and Young's modulus could reflect the bulk mechanical properties of the basic biodegradable polymer network, lacked the alkaline microenvironment-induced silane hydrolysis condensation and secondary crosslinking mechanism after hydration. Water entering the network mainly manifested as swelling and plasticization, leading to a decrease in both tensile strength and Young's modulus. This result indicates that the synergistic effect of the alkaline inorganic nanofillers and the self-reinforcing functional monomers is a crucial reason for the enhanced bulk mechanical properties achieved after hydration in this invention. It also further demonstrates that the alkaline microenvironment self-reinforcing system of this invention can improve the mechanical stability of the biodegradable bone adhesive during the wet functional phase.

[0034] (II) In vitro degradation performance test: The alkaline microenvironment-based self-reinforcing osteogenic adhesive was pre-molded in a polytetrafluoroethylene mold for 5 min, and the sample mass at this point was weighed and recorded as W0. The alkaline microenvironment-based self-reinforcing osteogenic adhesive was then immersed in a glass bottle containing 5 mL of 1 M NaOH solution and incubated at 37°C for accelerated in vitro degradation. The sample was removed after 7 days and washed with deionized water. Subsequently, the sample was freeze-dried overnight, and the sample mass at this point was weighed and recorded as W. d Degradation rate = (W0 - W) d ) / W0×100%.

[0035] The in vitro accelerated degradation test results of the adhesives prepared in Examples 1-4 and Comparative Examples 1-2 are as follows: Figure 4As shown in the figure, the degradation rates of Examples 1-4 are all below 40%, indicating that the present invention, by introducing cycloenol acetal monomers, forms hydrolyzable ester bonds in the polymer backbone after free radical ring-opening polymerization, thereby endowing the adhesive with degradable characteristics. Specifically, Example 1, using an MDO / HEMA monomer combination, achieved a degradation rate of 36.2%; Example 4, using a DMMDO / HPMA monomer combination, achieved a degradation rate of 28.1%. The difference in degradation behavior between the two examples mainly stems from the monomer structure's control over water diffusion and network hydrolysis: the polymer segments formed after DMMDO ring-opening have a stronger limiting effect on water penetration compared to the MDO system, and HPMA has a more pronounced hydrophobic side chain effect than HEMA, which can reduce the diffusion rate of water in the polymer network, thus relatively slowing down the degradation process of the DMMDO / HPMA system. These results demonstrate that the present invention can regulate the degradation behavior of the adhesive by adjusting the types of cycloenol acetal monomers and vinyl comonomers, endowing the material with degradability while maintaining structural stability during its functional life.

[0036] Comparative Example 1, Vetbond, a commercially available cyanoacrylate-based medical adhesive, showed a degradation rate close to 0, indicating that this type of commercial adhesive lacks hydrolyzable degradable structures and is unlikely to experience effective mass loss under alkaline accelerated degradation conditions. Comparative Example 2, without the introduction of the self-reinforcing functional monomer TESPMA and alkaline inorganic nanofillers, showed a degradation rate of 38.5%, indicating that the basic degradable polymer network formed only by cycloenone acetal monomers and vinyl comonomers contains hydrolyzable ester bonds, which can break under NaOH conditions and cause mass loss. Compared to Comparative Example 2, Examples 1-4, due to the introduction of self-reinforcing functional monomers and alkaline inorganic nanofillers, had a lower relative proportion of degradable ester bonds in the system. Simultaneously, the self-reinforcing network formed by the hydrolysis and condensation of TESPMA and the inorganic filler phase composed of nano-magnesium oxide limited water penetration and rapid network disintegration. Therefore, the degradation rates of Examples 1-4 were slightly lower than Comparative Example 2, but still maintained a clear degradation behavior, indicating that the alkaline microenvironment self-reinforcing system did not block material degradation but rather made the degradation process more controlled. The above results demonstrate that the self-reinforcing osteogenic adhesive based on an alkaline microenvironment provided by this invention possesses both degradability and degradation control capabilities. By adjusting the composition of cycloenol acetal monomer, vinyl comonomer, self-reinforcing functional monomer, and alkaline inorganic nanofiller, it can maintain structural stability during the bone tissue fixation functional period and gradually degrade after the functional period.

[0037] (iv) Osteoblast activity test: Osteoblast MC3T3-E1 cells were seeded onto the adhesive surfaces prepared in Examples 1-4 and Comparative Example 2, respectively. After culturing for 7 and 14 days, the old culture medium was discarded, and the cells were washed 1-3 times with PBS, followed by lysis with RIPA cell lysis buffer. After complete cell lysis, the cell lysis buffer was centrifuged, the supernatant was collected, and the cell ALP activity was measured according to the alkaline phosphatase (ALP) assay kit instructions.

[0038] The ALP activity detection results of the material surface cells in Examples 1-4 and Comparative Example 2 are as follows: Figure 5 As shown in the figure, the ALP activity of Examples 1-4 after 7 and 14 days of culture was significantly higher than that of Comparative Example 2, and the ALP activity at 14 days of culture was further increased compared to 7 days (up to 0.89), indicating that the material of the present invention can promote early osteogenic differentiation of osteoblasts. This is because Examples 1-4 all introduced nano-magnesium oxide and the self-reinforcing functional monomer TESPMA. Nano-magnesium oxide can undergo hydration in a humid environment and form a local alkaline microenvironment. This microenvironment is conducive to promoting the hydrolysis and condensation reaction of the silane groups in TESPMA, so that the adhesive network further hardens during hydration and forms a mechanically reinforced structure. At the same time, the magnesium ions generated by magnesium oxide hydration and the local weakly alkaline environment can provide favorable conditions for osteoblast adhesion, proliferation and osteogenic differentiation. Compared with Comparative Example 2, which lacks TESPMA and nano-magnesium oxide, Examples 1-4 not only have a degradable adhesive network, but also can enhance ALP activity through synergistic mechanical reinforcement and osteogenic regulation by the alkaline microenvironment. The above results indicate that the self-reinforcing osteogenic adhesive based on an alkaline microenvironment constructed in this invention can provide a favorable microenvironment for early osteoblast differentiation while achieving bone tissue adhesion and fixation.

[0039] In summary, this invention proposes an osteogenic adhesion strategy based on self-reinforcement induced by an alkaline microenvironment. A biodegradable bone adhesive network is constructed using cycloenol acetal monomers and vinyl comonomers, and self-reinforcing functional monomers and alkaline inorganic nanofillers are introduced. While maintaining effective bone tissue adhesion, this significantly improves the bulk mechanical properties after hydration, achieving a synergistic enhancement of the material's bulk mechanical stability and bone interface fixation ability during the wet functional period. Furthermore, this invention introduces hydrolyzable ester bonds into the polymer backbone through free radical ring-opening polymerization of cycloenol acetal monomers, enabling the self-reinforced osteogenic adhesive based on an alkaline microenvironment to possess post-functional degradability. The alkaline inorganic nanofillers construct an osteogenic-friendly local microenvironment, achieving synergistic effects of adhesion fixation, mechanical enhancement, and osteogenic regulation. This significantly increases the alkaline phosphatase activity of osteoblast MC3T3-E1 cells on the material surface, providing a material platform with both adhesion fixation and osteogenic induction potential for bone defect repair and bone tissue regeneration.

[0040] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0041] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A self-reinforcing osteogenic adhesive based on an alkaline microenvironment, characterized in that, Includes the following components: Cycloenol acetal monomer, vinyl comonomer, self-reinforcing functional monomer, crosslinking agent and alkaline inorganic nanofiller; The self-reinforcing functional monomer is any one or at least a combination of two of the following: 3-(methacryloyloxy)propyltrimethoxysilane, 3-(methacryloyloxy)propyltriethoxysilane, 3-(acryloyloxy)propyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, 3-isopropenyl-α,α-dimethylbenzyl isocyanate, methacryloyloxyethyl isocyanate, acryloyloxyethyl isocyanate, methacryloyl isocyanate, and acryloyl isocyanate. The alkaline inorganic nanofiller is any one or at least a combination of two of the following: nano magnesium oxide, nano calcium oxide, nano zinc oxide, nano magnesium hydroxide, nano calcium hydroxide, nano hydroxyapatite, and nano bioactive glass.

2. The self-reinforcing osteogenic adhesive based on an alkaline microenvironment according to claim 1, characterized in that, The cycloenone acetal monomer is any one or at least a combination of two of the following: 2-methylene-1,3-dioxane, 4,7-dimethyl-2-methylene-1,3-dioxane, 5,6-benzo-2-methylene-1,3-dioxane, 4-methylene-2-phenyl-1,3-dioxane, 2-methylene-1,3-dioxane, and 4,4-dimethyl-2-methylene-1,3-dioxane; the vinyl comonomer is hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, methyl... The cycloenyl acetal monomer, vinyl comonomer, and self-reinforcing functional monomer are selected from the following: 4-hydroxybutyl acrylate, 4-hydroxybutyl acrylate, glycidyl methacrylate, glycidyl acrylate, methacrylamide, acrylamide, N-(2-hydroxyethyl)methacrylamide, N-(2-hydroxyethyl)acrylamide, N,N-dimethylmethacrylamide, N,N-dimethylacrylamide, polyethylene glycol monomethacrylate, polyethylene glycol monoacrylate, and N-vinylpyrrolidone, or at least two combinations thereof; wherein the molar ratio of the cycloenyl acetal monomer, vinyl comonomer, and self-reinforcing functional monomer is 0.1~10:1:0.05~1.

3. The self-reinforcing osteogenic adhesive based on an alkaline microenvironment according to claim 1, characterized in that, The crosslinking agent is any one or a combination of at least two of the following: ethylene glycol dimethacrylate, N,N'-methylenebisacrylamide, diethylene glycol dimethacrylate, diethylene glycol diacrylate, polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, trimethylolpropane trimethacrylate, and trimethylolpropane triacrylate; the molar fraction of the crosslinking agent in the total molar fraction of the cycloenone acetal monomer, vinyl comonomer, and self-reinforcing functional monomer is 0.2 mol% to 30 mol.

4. The self-reinforcing osteogenic adhesive based on an alkaline microenvironment according to claim 1, characterized in that, The alkaline inorganic nanofiller accounts for 0.2% to 15% of the total mass of the cycloenone acetal monomer, vinyl comonomer, and self-reinforcing functional monomer.

5. The self-reinforcing osteogenic adhesive based on an alkaline microenvironment according to claim 1, characterized in that, The alkaline microenvironment-based self-reinforcing osteogenic adhesive also includes a redox initiation system, which is obtained by mixing an oxidant and a reducing agent, with a molar ratio of 1:0.2~5; the redox initiation system accounts for 0.1mol%~5mol% of the molar fraction of the cycloenol acetal monomer, vinyl comonomer and self-reinforcing functional monomer.

6. A method for preparing a self-reinforcing osteogenic adhesive based on an alkaline microenvironment as described in any one of claims 1-5, characterized in that, The preparation steps include the following: The cycloenone acetal monomer, vinyl comonomer, self-reinforcing functional monomer, alkaline inorganic nanofiller and crosslinking agent are mixed evenly, and then an oxidant and a reducing agent are added and mixed evenly to obtain a precursor mixture. In-situ ring-opening polymerization reaction is carried out and cured to obtain a self-reinforcing osteogenic adhesive based on an alkaline microenvironment.

7. The preparation method of the self-reinforcing osteogenic adhesive based on an alkaline microenvironment according to claim 6, characterized in that, The in-situ ring-opening polymerization reaction takes 1 to 10 minutes and is carried out at a temperature of 20°C to 37°C.

8. The application of an alkaline microenvironment-based self-reinforcing osteogenic adhesive prepared by any one of claims 1-5 or by the preparation method of claim 6 or 7, characterized in that, It is used in the field of medical adhesives.

9. The application of the self-reinforcing osteogenic adhesive based on an alkaline microenvironment according to claim 8, characterized in that, In the field of medical adhesive materials used for fracture repair and bone defect treatment, the application steps of the self-reinforcing osteogenic adhesive based on an alkaline microenvironment are as follows: The precursor mixture is applied to the bone bonding interface, where an in-situ ring-opening polymerization reaction occurs, followed by curing to complete the bone bonding.

10. The application of the self-reinforcing osteogenic adhesive based on an alkaline microenvironment according to claim 8, characterized in that, The precursor mixture is applied to the bonding interface by in-situ coating, injection, or filling; the bone bonding interface is a flat surface or any irregular cross-section.

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