Self-lubricating anti-degradation hydrogel core-shell microspheres, preparation method and application

Abstract

The application relates to the technical field of biomedical materials, in particular to a self-lubricating anti-degradation hydrogel core-shell microsphere, a preparation method and application. The microsphere comprises a core and a shell layer; the core is a gel micro-core formed by photo-crosslinking of a photo-cured monomer; the gel micro-core is loaded with a drug; the shell layer is a lubricating anti-degradation layer formed by photo-crosslinking polymerization of a hydrophilic zwitterionic polymer and polyethylene glycol diacrylate after blending; the particle size of the core is 45-280 mu m, and the thickness of the shell layer is 0.1-20 mu m. The scheme provided in the application can load the drug in the core and provide the lubricating anti-degradation function, solves the problems of insufficient lubrication persistence, high enzymatic degradation sensitivity and uncontrollable drug release in the joint cavity, and has the advantages of long-acting lubrication, anti-degradation and controllable drug slow release.

Description

Technical Field

[0001] This application relates to the field of biomedical materials technology, and in particular to a self-lubricating and degradation-resistant hydrogel core-shell microsphere, its preparation method, and its application. Background Technology

[0002] With the aging population and the increase in obesity, osteoarthritis has become one of the leading causes of joint pain and motor dysfunction in middle-aged and elderly people. Studies have shown that during the development of osteoarthritis, decreased joint lubrication, increased levels of reactive oxygen species (ROS), and imbalance of the inflammatory microenvironment are important factors leading to the continuous degeneration of cartilage. Currently, intra-articular injection of hyaluronic acid to improve the lubrication environment or oral medication to relieve pain are commonly used to treat osteoarthritis. However, traditional hyaluronic acid has a short retention time in the joint cavity, is easily degraded by enzymes, or is rapidly cleared away with the synovial fluid circulation, resulting in a limited duration of lubrication and requiring frequent injections, which affects treatment adherence. Drug treatment mainly uses non-steroidal anti-inflammatory drugs (NSAIDs) and analgesics. Although they can relieve pain and inflammation, long-term use can easily produce systemic side effects, and their drug concentration in the joint cavity is insufficient and their retention time is short, limiting their effect on cartilage repair.

[0003] In recent years, hydrogel materials have been widely used in joint disease research due to their excellent water content, biocompatibility, and physical properties similar to the natural extracellular matrix. However, traditional bulk hydrogels still have significant limitations in intra-articular applications, such as difficult injection, insufficient adaptability to joint movement, and limited stability under dynamic mechanical environments. To overcome these shortcomings, hydrogel microspheres have gradually attracted widespread attention from researchers. Compared to bulk hydrogels, hydrogel microspheres have controllable size, large specific surface area, and good injectability, enabling uniform dispersion through intra-articular injection and better adapting to the complex joint movement environment. Simultaneously, the microsphere structure facilitates drug loading and diffusion regulation, which can prolong the drug's residence time in the joint cavity to a certain extent, thus showing promising application prospects in the treatment of osteoarthritis and drug sustained release.

[0004] However, existing hydrogel microsphere systems still face several key challenges. For example, the surface lubrication capacity of ordinary hydrogel microspheres is limited, and their lubrication performance mainly depends on the water content of the material itself. Under continuous friction and compression conditions, the stability of the hydration layer is insufficient, making it difficult to maintain a low-friction state for a long time. Secondly, the joint cavity is rich in degrading enzymes such as hyaluronidase and matrix metalloproteinases, and traditional hydrogel microspheres are prone to rapid enzymatic degradation, resulting in a limited material action time.

[0005] Therefore, developing a core-shell structured hydrogel microsphere with excellent lubrication properties, good resistance to enzyme degradation, and controllable drug release is of great significance for improving the joint microenvironment in osteoarthritis, prolonging the material's action time, and enhancing the therapeutic effect. Summary of the Invention

[0006] One of the purposes of this application is to overcome the shortcomings of the prior art by providing a self-lubricating and degradation-resistant hydrogel core-shell microsphere, which can provide lubrication and degradation resistance by loading drugs in the core and providing the shell layer, thus solving the problems of insufficient lubrication durability in the joint cavity, high sensitivity to enzyme degradation and uncontrollable drug release, and has the advantages of long-lasting lubrication, degradation resistance and controllable drug release.

[0007] The second objective of this application is to provide a method for preparing self-lubricating and degradation-resistant hydrogel core-shell microspheres.

[0008] The third objective of this application is to provide a self-lubricating and degradation-resistant hydrogel core-shell microsphere for the preparation of osteoarthritis treatment agents, rheumatoid arthritis treatment agents, articular cartilage repair agents, joint cavity lubrication agents, or long-acting drug sustained-release carriers.

[0009] One of the objectives of this application is achieved through the following technical solution: A self-lubricating and degradation-resistant hydrogel core-shell microsphere is provided, comprising a core and a shell; The core is a gel micronucleus formed by photocuring monomers through photocrosslinking; The gel micronuclei are loaded with drugs; The shell layer is a lubricating and anti-degradation layer formed by photocrosslinking polymerization of a hydrophilic zwitterionic polymer and polyethylene glycol diacrylate. The kernel has a particle size of 45~280μm, and the shell has a thickness of 0.1~20μm.

[0010] In some embodiments, the photocurable monomer is selected from at least one of modified hyaluronic acid and modified gelatin; The hydrophilic zwitterionic polymer is selected from at least one of methacryloyl ethyl sulfobetaine and carboxybetaine methacrylate.

[0011] In some embodiments, the drug is selected from at least one of diclofenac sodium, dexamethasone, ibuprofen, dopamine, resveratrol, curcumin, metformin, Kartogenin, growth factors, and nanoparticles.

[0012] In some embodiments, the modification of the modified hyaluronic acid includes any one of carbon-carbon double bond modification, aldehyde modification, aldehyde-carbon-carbon double bond double modification, carbon-carbon double bond-dopamine double modification, and carbon-carbon double bond-phenylboronic acid double modification. The modified hyaluronic acid has a molecular weight of 50-120 kDa, and the modified gelatin has a molecular weight of 100-200 kDa.

[0013] The self-lubricating and degradation-resistant hydrogel core-shell microspheres of this application have the following beneficial effects: The self-lubricating, anti-degradation hydrogel core-shell microspheres provided in this application utilize a highly hydrophilic copolymer shell. On one hand, the shell reduces the interfacial friction coefficient through stable hydration, ensuring long-lasting lubrication. On the other hand, it blocks the contact between degrading enzymes and the core matrix, delaying the enzymatic degradation process and thus extending the material's residence time at the site of action. The core serves as a storage region for active components, suitable for loading and controlled release of various drugs, including anti-inflammatory, antioxidant, and cartilage repair drugs. Combined with the shell's interfacial regulation capabilities, the microspheres maintain good structural stability while possessing multiple functions such as lubrication and protection, long-lasting sustained release, and targeted therapy, thereby meeting the practical application needs of minimally invasive treatment of joint diseases.

[0014] The second objective of this application is achieved through the following technical solution: A method for preparing self-lubricating and degradation-resistant hydrogel core-shell microspheres is provided, comprising the following steps: S1. Dissolve the photocurable monomer in PBS buffer, stir well, add at least one drug, then add the first photoinitiator, mix well to obtain the hydrogel precursor; S2. Add the hydrogel precursor to the continuous phase, vortex for 20~120s, and then obtain gel micronuclei by photo-induced polymerization. S3. Dissolve the second photoinitiator in PBS buffer to obtain a photoinitiator solution, and then immerse the gel micronucleus in the photoinitiator solution for 30s~120s to allow the second photoinitiator to diffuse to the surface of the gel micronucleus and obtain the microgel core. S4. Add the hydrophilic zwitterionic polymer and polyethylene glycol diacrylate to PBS buffer and mix to obtain a mixed solution; S5. The microgel core is transferred to a mixed solution and left to stand for 30-120 seconds. After in-situ photopolymerization, the microgel core-shell microspheres are collected and washed to obtain the self-lubricating and degradation-resistant hydrogel core-shell microspheres.

[0015] In some embodiments, in step S1, the amount of the photocurable monomer added is 2-20 w / v% of the PBS buffer volume. The amount of the first photoinitiator added is 0.1~0.5 w / v of the PBS buffer volume; the first photoinitiator is selected from Irgacure 2959 or lithium phenyl-2,4,6-trimethylbenzoylphosphonate.

[0016] In some embodiments, in step S2, the volume ratio of the hydrogel precursor to the continuous phase is 1:(5~8), and the continuous phase is a mixture of fluorinated oil and emulsifier; The emulsifier is FluoSurf 2 wt.% in Fluo-Oil 7500 fluorinated oil solution, and the content of the emulsifier in the continuous phase is 0.2%~0.4%; In steps S2 and S5, the curing time under light is 30~120s.

[0017] In some embodiments, in step S3, the amount of the second photoinitiator added is 1 to 5 w / v% of the PBS buffer volume, and the second photoinitiator may be the same as or different from the first photoinitiator.

[0018] In some embodiments, the amount of the hydrophilic zwitterionic polymer added is 5-15 w / v of the PBS buffer volume, and the amount of the polyethylene glycol diacrylate added is 10-20 w / v of the PBS buffer volume.

[0019] The method for preparing self-lubricating and degradation-resistant hydrogel core-shell microspheres in this application has the following beneficial effects: The preparation method described in this application allows for control of the microgel core particle size by adjusting the vortex shearing time. Furthermore, the shell thickness can be flexibly adjusted by regulating the immersion time and number of immersions of the microgel core in a mixed solution of hydrophilic zwitterionic polymer and polyethylene glycol diacrylate, thereby producing core-shell microspheres of different sizes. The preparation process is simple, the reaction conditions are mild, and there are no harmful byproducts, making it environmentally friendly. The resulting microspheres exhibit excellent structural stability, facilitating storage and transportation. All raw materials used are readily available for industrial production, widely sourced, and cost-effective, demonstrating good potential for large-scale production and commercialization.

[0020] The third objective of this application is achieved through the following technical solution: The above-mentioned self-lubricating and degradation-resistant hydrogel core-shell microspheres are provided for use in the preparation of osteoarthritis treatment agents, rheumatoid arthritis treatment agents, articular cartilage repair agents, joint cavity lubrication agents, or long-acting drug sustained-release carriers. The self-lubricating and degradation-resistant hydrogel core-shell microspheres are the self-lubricating and degradation-resistant hydrogel core-shell microspheres described in the above technical solution or the self-lubricating and degradation-resistant hydrogel core-shell microspheres prepared by the above preparation method.

[0021] The self-lubricating and anti-degradation hydrogel core-shell microspheres of this application can be loaded with different types of active drugs or functional components according to clinical needs, so as to achieve precise adaptation to different joint disease indications and different medication needs. At the same time, the low friction lubrication properties and anti-degradation stability of the microspheres can improve the lubrication environment of the joint cavity and reduce joint wear in the long term. It can achieve multi-effect synergy of lubrication-treatment-repair without the need for repeated administration, which can significantly reduce the medical costs and treatment pain of patients and has extremely high clinical application value. Attached Figure Description

[0022] The above and other objects, features and advantages of this application will become more apparent from the more detailed description of exemplary embodiments thereof in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments thereof.

[0023] Figure 1 The 1H NMR spectrum of the aldehyde group and double bond modified hyaluronic acid in Example 1 is shown. Figure 2 This is an optical image of the self-lubricating and degradation-resistant hydrogel core-shell microspheres of Example 1 dispersed in PBS; Figure 3 This is a particle size distribution chart of the self-lubricating and degradation-resistant hydrogel core-shell microspheres in Example 1; Figure 4 Fluorescent images of the self-lubricating and degradation-resistant hydrogel core-shell microspheres in Example 1; Figure 5 This is an optical image of the self-lubricating and degradation-resistant hydrogel core-shell microspheres dispersed in PBS in Example 2; Figure 6 This is a particle size distribution chart of the self-lubricating and degradation-resistant hydrogel core-shell microspheres in Example 2; Figure 7 This is a particle size distribution chart of the self-lubricating and degradation-resistant hydrogel core-shell microspheres in Example 3; Figure 8 The degradation curves of the self-lubricating and degradation-resistant hydrogel core-shell microspheres in Examples 2 and 3 are shown. Figure 9 The drug release curves are for the self-lubricating and degradation-resistant hydrogel core-shell microspheres in Examples 1 and 4. Figure 10 Tribological performance tests were conducted on the self-lubricating and degradation-resistant hydrogel core-shell microspheres in Examples 4 and 5. Figure 11 The particle size distribution of the self-lubricating and degradation-resistant hydrogel core-shell microspheres in Example 6 is shown in the figure. Figure 12 This image shows the therapeutic effect of the self-lubricating and degradation-resistant hydrogel core-shell microspheres from Example 7 on MIA-induced osteoarthritis in rats. Detailed Implementation

[0024] Preferred embodiments of the present application will now be described in more detail with reference to the accompanying drawings. While preferred embodiments of the present application are shown in the drawings, it should be understood that the present application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make the present application more thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

[0025] Traditional treatments for osteoarthritis, such as intra-articular injection of hyaluronic acid, suffer from short retention time and easy degradation, while drug therapy faces challenges related to systemic side effects and insufficient intra-articular concentration. Traditional hydrogel materials have limitations in intra-articular applications, including difficult injection, poor adaptability to movement, and insufficient stability. Existing hydrogel microsphere systems have limited surface lubrication and anti-enzymatic degradation capabilities, and their action time is also limited.

[0026] To address the aforementioned issues, this application proposes a self-lubricating and degradation-resistant hydrogel core-shell microsphere. This microsphere can provide lubrication and degradation resistance by loading drugs into the core and using the shell, thus solving the problems of insufficient lubrication persistence in the joint cavity, high sensitivity to enzyme degradation, and uncontrollable drug release. It has the advantages of long-lasting lubrication, degradation resistance, and controllable drug release. The hydrogel core-shell microsphere specifically includes a core and a shell. The core is a gel micronucleus formed by photocuring monomers through photocrosslinking; The gel micronuclei are loaded with drugs; The shell layer is a lubricating and anti-degradation layer formed by photocrosslinking polymerization of a hydrophilic zwitterionic polymer and polyethylene glycol diacrylate. The core has a particle size of 45~280μm, and the shell has a thickness of 0.1~20μm.

[0027] Furthermore, this application also proposes a method for preparing self-lubricating and degradation-resistant hydrogel core-shell microspheres, specifically including the following steps: S1. Dissolve the photocurable monomer in PBS buffer, stir well, add at least one drug, then add the first photoinitiator, mix well to obtain the hydrogel precursor; S2. Add the hydrogel precursor to the continuous phase, vortex for 20~120s, and then obtain gel micronuclei by photo-induced polymerization. S3. Dissolve the second photoinitiator in PBS buffer to obtain a photoinitiator solution, and then immerse the gel micronucleus in the photoinitiator solution for 30s~120s to allow the second photoinitiator to diffuse to the surface of the gel micronucleus and obtain the microgel core. S4. Add the hydrophilic zwitterionic polymer and polyethylene glycol diacrylate to PBS buffer and mix to obtain a mixed solution; S5. The microgel core is transferred to a mixed solution and left to stand for 30-120 seconds. After in-situ photopolymerization, the microgel core-shell microspheres are collected and washed to obtain the self-lubricating and degradation-resistant hydrogel core-shell microspheres.

[0028] In step S1, the amount of photocurable monomer added is 2~20 w / v of the PBS buffer volume; the amount of first photoinitiator added is 0.1~0.5 w / v of the PBS buffer volume. The first photoinitiator can be Irgacure 2959 or lithium phenyl-2,4,6-trimethylbenzoylphosphonate (LAP), and the photocurable monomer can be one or a combination of modified hyaluronic acid and modified gelatin.

[0029] When modified hyaluronic acid is selected as the photocurable monomer, the modification method of hyaluronic acid can be any one of carbon-carbon double bond modification, aldehyde modification, aldehyde-carbon-carbon double bond double modification, carbon-carbon double bond-dopamine double modification, or carbon-carbon double bond-phenylboronic acid double modification. Among these, carbon-carbon double bond modification refers to introducing photopolymerizable methacrylate / acrylate groups onto the hyaluronic acid molecular chain. Under the action of a first photoinitiator, the carbon-carbon double bond undergoes free radical polymerization triggered by light, achieving cross-linking and curing of hyaluronic acid to form a stable three-dimensional gel network. Aldehyde group modification refers to introducing highly reactive aldehyde groups onto the hyaluronic acid molecular chain, which can undergo Schiff base reactions or acetal reactions with biomolecules containing amino or hydroxyl groups, providing additional cross-linking mechanisms or bioactive coupling sites for the gel micronucleus. Aldehyde-carbon-carbon double bond dual modification refers to combining the advantages of the above two modifications, where the hyaluronic acid molecule simultaneously carries aldehyde groups and carbon-carbon double bonds, enabling multiple cross-linking: the carbon-carbon double bond forms the main cross-linking network through photopolymerization, while the aldehyde group can form auxiliary cross-links with the amino components in the system or be used for subsequent biomolecule coupling, simultaneously enhancing the gel. Mechanical properties and biofunctional compatibility; Carbon-carbon double bond-dopamine dual modification refers to the simultaneous introduction of carbon-carbon double bonds and dopamine groups into hyaluronic acid molecules. Carbon-carbon double bonds are used for photocrosslinking to construct the gel framework, while dopamine groups can enhance the interfacial bonding force between the gel micronucleus and the shell, or endow microspheres with the ability to adhere to biological tissues. On the other hand, dopamine has its own antioxidant activity, which can remove excess reactive oxygen species in the joint cavity and improve the inflammatory microenvironment; Carbon-carbon double bond-phenylboronic acid dual modification refers to the simultaneous carrying of carbon-carbon double bonds and phenylboronic acid groups into hyaluronic acid molecules. Carbon-carbon double bonds are used for photocrosslinking to form a network, while phenylboronic acid can form reversible covalent bonds with substances containing vicinal diol structures, endowing the gel micronucleus with pH responsiveness or glucose responsiveness, adapting to the intelligent release needs such as pH-responsive drug release in the inflammatory microenvironment of osteoarthritis and glucose-responsive drug release in diabetes-related bone diseases.

[0030] Furthermore, this method preferably uses modified hyaluronic acid with a molecular weight of 50-120 kDa and modified gelatin with a molecular weight of 100-200 kDa.

[0031] For modified hyaluronic acid with a molecular weight of 50-120 kDa, a suitable precursor solution viscosity can be provided, which matches the droplet breakup-stabilization kinetics of the vortex shearing process and facilitates subsequent clinical injection. If the molecular weight is below 50 kDa, the precursor viscosity is too low, the interfacial tension of the droplets formed by vortex shearing is insufficient, and aggregation and breakup are very likely to occur, resulting in difficulties in nucleation and extremely low microsphere yield. In addition, the cross-linked network structure of low molecular weight hyaluronic acid is loose, and the mechanical properties of the microspheres are insufficient, making them easily brittle and losing structural integrity under the dynamic shearing environment in vivo. If the molecular weight is above 120 kDa, the precursor viscosity is too high, the fluidity is significantly reduced, the molecular chain entanglement is enhanced, and vortex shearing is difficult to uniformly break the viscous aqueous phase into monodisperse droplets. During photopolymerization, irregular aggregates are easily formed, resulting in difficulties in nucleation, poor sphericity after sphere formation, and wide particle size distribution. At the same time, excessively high viscosity will lead to excessive injection resistance during microsphere injection, affecting the convenience of clinical operation.

[0032] For modified gelatin with a molecular weight of 100–200 kDa, it can simultaneously meet the multi-dimensional requirements of gel network mechanical strength, drug loading capacity, and degradation rate. If the molecular weight is below 100 kDa, the cross-linked gelatin network pore size is too large, making it prone to burst release of small molecule drugs, and the microspheres have insufficient resistance to degradation, resulting in a shortened in vivo retention period. If the molecular weight is above 200 kDa, it will also lead to excessively high precursor viscosity, making droplet dispersion difficult, and the degradation rate after cross-linking is too slow, which does not match the 2–4 week cycle of articular cartilage repair and poses a risk of foreign body reaction. Under the premise of the above molecular weight, with the subsequent control of vortex shearing time, the microsphere particle size can be precisely and repeatedly controlled in the range of 45–280 μm, adapting to the performance requirements of different application scenarios.

[0033] Furthermore, the drug can be selected from at least one of the following based on different therapeutic goals: anti-inflammatory, analgesic, cartilage protection, cartilage repair, and tissue regeneration: diclofenac sodium, dexamethasone, ibuprofen, dopamine, resveratrol, curcumin, metformin, Kartogenin, growth factors, and functional nanoparticles. The drug loading method can be at least one of physical encapsulation and chemical bonding. For example, when metformin is metformin hydrochloride, the amino group of metformin combines with the aldehyde group of AHAMA to form a dynamic Schiff base bond, thereby achieving metformin loading.

[0034] In step S2, the continuous phase provides an oil-phase environment for emulsion nucleation of the hydrogel precursor, specifically a mixture of fluorinated oil and emulsifier. Fluorinated oil is immiscible with the aqueous phase and has low surface tension and good biocompatibility, which can prevent the hydrogel precursor droplets from coalescing; the emulsifier can reduce the interfacial tension between the water and oil phases, stabilize the emulsion droplets, and prevent the hydrogel precursor from coalescing before and after polymerization.

[0035] Furthermore, the volume ratio of the hydrogel precursor to the continuous phase is 1:(5~8); the emulsifier is FluoSurf 2wt.% in Fluo-Oil 7500 fluorinated oil solution, and the content of the emulsifier in the continuous phase is 0.2%~0.4%.

[0036] To precisely control the size and spheroidization quality of the gel micronuclei, the vortexing time was set to 20–120 s, and the photocuring time was set to 30–120 s. Specifically, after the hydrogel precursor was added to the fluorinated oil continuous phase as the dispersed phase, the shear force provided by the vortex first tore the large aqueous phase into initial large droplets. As the vortexing time increased, the shearing action continued to break the large droplets into smaller droplets. At the same time, the emulsifier molecules in the continuous phase were rapidly adsorbed onto the newly formed oil-water interface to form a stable interfacial film, preventing droplet aggregation. When the vortexing time was short, the shearing action was insufficient, the large droplets were not completely broken up, and the probability of droplet collision and aggregation was higher, resulting in larger final microsphere sizes. When the vortexing time was extended, the droplets were sufficiently sheared and broken up, and the emulsifier also had sufficient time to complete interfacial adsorption. The droplet size gradually stabilized within a smaller range until the shearing rate and the droplet aggregation rate reached equilibrium.

[0037] In step S3, the second photoinitiator used in this step has the same composition as the first photoinitiator in step S1. The purpose of this step is to construct an active region rich in photoinitiators on the surface of the gel micronucleus, providing reaction sites for the subsequent in-situ polymerization of the shell and ensuring the tight bonding between the shell and the core.

[0038] In step S4, the hydrophilic zwitterionic polymer can be methacryloyl ethyl sulfobetaine (SBMA) and / or carboxybetaine methacrylate (CBMA), and the amount added is 5-15 w / v of the PBS buffer volume, and the amount added is 10-20 w / v of the PBS buffer volume.

[0039] The combination of raw materials selected in this step is used to achieve shell lubrication and anti-degradation. The hydrophilic zwitterionic polymer molecules carry equal amounts of positive and negative charges, which can bind a large number of stable water molecules on the surface through electrostatic-dipole interactions to form a dense hydration layer. This not only reduces the coefficient of friction to achieve long-term lubrication, but also blocks the adsorption and accumulation of degrading enzymes such as hyaluronidase and matrix metalloproteinase on the surface of the microspheres by resisting non-specific adsorption effects, thus avoiding direct contact between enzymes and the core matrix. The cross-linked polyethylene glycol diacrylate forms a dense and flexible network, which can act as a physical barrier to prevent the penetration of degrading enzyme molecules into the core. At the same time, the PEG segments themselves have excellent anti-enzymatic properties and will not be decomposed by common degrading enzymes in the joint cavity. With the synergistic effect of the two, the anti-enzymatic degradation cycle of the core-shell microspheres is increased by 5 to 6 times compared with pure hyaluronic acid microspheres, and can achieve long-term in vivo retention of more than 28 days.

[0040] In particular, steps S3 and S4 can be repeated once or more to gradually increase the shell thickness and adapt to the usage requirements of different degradation cycles and drug release rates.

[0041] The beneficial effects of this application will be further illustrated below with reference to the embodiments. All components described in this application are obtained commercially available. The components described in the specific implementation or embodiments are mass ratios or mass parts.

[0042] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0043] In this application description, AHA is aldehyde-modified hyaluronic acid, HAMA is double-bond modified hyaluronic acid, and AHAMA is aldehyde / carbon-carbon double-bond modified hyaluronic acid.

[0044] Example 1 (1) Synthesis of AHAMA: 1 g of sodium hyaluronate was dissolved in 100 mL of deionized water and stirred until completely dissolved. Then, 5 mL of 0.5 M sodium periodate solution was slowly added dropwise. The reaction was carried out at room temperature in the dark with stirring for 2 h. The reaction was terminated by adding 1 mL of ethylene glycol, and stirring was continued for 1 h. The reaction solution was then transferred to a dialysis bag, dialyzed with deionized water for 3 days, and then freeze-dried to obtain aldehyde-modified hyaluronic acid (AHA). Under ice bath conditions, 1 g of AHA was dissolved in 100 mL of deionized water, followed by the addition of 1 mL of methacrylic anhydride. The pH of the reaction system was adjusted to 8-8.5 using NaOH solution. The reaction was maintained under ice bath conditions for 2 h, then transferred to 4 °C and stirred overnight. The resulting reaction solution was dialyzed with deionized water for 5 days and then freeze-dried to obtain aldehyde / carbon-carbon double bond modified hyaluronic acid (AHAMA).

[0045] (2) Preparation of drug-loaded hydrogel micronuclei by emulsion method: 40 mg AHAMA, 1 mmol metformin hydrochloride, and 1 mg lithium phenyl-2,4,6-trimethylbenzoylphosphonate (LAP) were added to 1 mL of PBS buffer and stirred until completely dissolved. The pH of the system was adjusted to 7.5–8.0 using NaOH solution to allow the amino group of metformin to bind with the aldehyde group of AHAMA to form a dynamic Schiff base bond, achieving drug chemical bonding loading. The above mixture was added to 5 mL of a continuous phase containing 0.25 wt% fluorinated oil surfactant, vortexed for 40 s, and sheared to form uniform microdroplets. UV irradiation for 1 min initiated cross-linking, yielding the drug-loaded microgel core.

[0046] (3) Preparation of hydrophilic lubricating and anti-degradation shell: The obtained microgel cores were immersed in PBS buffer containing 1 w / v% LAP for 60 s to allow the initiator to diffuse to the surface of the micronucleus. Subsequently, the micronucleus was transferred to a mixed solution containing 5 w / v% methacryloyl ethyl sulfobetaine (SBMA) and 10 w / v% polyethylene glycol diacrylate (PEGDA) and allowed to stand for 30 s. In situ polymerization was initiated by UV irradiation for 30 s, forming a lubricating and anti-degradation shell on the surface of the micronucleus. After washing and collection, the target core-shell hydrogel microspheres were obtained.

[0047] Characterization results: Figure 1 The 1H NMR spectrum of AHAMA from Example 1 shows that both AHAMA and HAMA (modified hyaluronic acid with a single carbon-carbon double bond) exhibit characteristic peaks near 5.86 ppm and 6.18 ppm, corresponding to the proton signals of the C=C bond in the methacrylate structure. Both AHAMA and AHA exhibit characteristic peaks at 4.9 ppm and 5.1 ppm, corresponding to the proton signals of the hemiacetal formed by the aldehyde group and the adjacent hydroxyl group, proving that AHAMA was successfully synthesized.

[0048] Figure 2 Optical microscope image of the core-shell hydrogel microspheres prepared in Example 1 in PBS.

[0049] Figure 3 The particle size distribution is as follows: the microspheres have regular morphology and are uniformly dispersed, with an average particle size of 113.06±16.07 μm.

[0050] Figure 4 Laser confocal microscopy images of microspheres with cores and shells labeled with different fluorescent substances: the microspheres have a distinct core-shell partitioning structure, and the shells are completely encapsulated.

[0051] Example 2 The AHAMA synthesis steps in this embodiment are the same as in Example 1, except that the vortex time in the micronucleus preparation process by emulsion method is adjusted to 60 s, and the other preparation parameters are the same as in Example 1.

[0052] Characterization results: Figure 5 This is a dispersion image of the core-shell microspheres prepared in Example 2 in PBS. Figure 6 The particle size distribution is as follows: the average particle size of the microspheres is 83.62 ± 10.38 μm, which is smaller than that of Example 1.

[0053] Example 3 The AHAMA synthesis steps and micronucleus preparation steps in this embodiment are the same as in Example 2. The shell preparation step is repeated twice to obtain double-shell core-shell hydrogel microspheres. The remaining parameters are the same as in Example 2.

[0054] Characterization results: Figure 7 The particle size distribution of the double-shelled microspheres prepared in Example 3 is as follows: the average particle size is 87.64 ± 10.67 μm, which is an increase compared to the single-shelled microspheres in Example 2.

[0055] Figure 8 The in vitro degradation curves of the microspheres (test conditions: 37°C, soaking in PBS solution containing hyaluronidase): the pure core microspheres without shells were almost completely degraded on day 5. The degradation cycle of the single-shell microspheres in Example 2 was as long as 28 days, and the degradation rate of the double-shell microspheres in Example 3 was even slower. This proves that the shell can significantly delay the enzymatic degradation process of the microspheres, and the degradation rate can be flexibly controlled by adjusting the shell thickness / number of layers.

[0056] Example 4 (1) Synthesis of single-carbon double bond modified hyaluronic acid (HAMA): Under ice bath conditions, 1 g of hyaluronic acid was dissolved in 100 mL of deionized water, and then 1 mL of methacrylic anhydride was added. The pH of the reaction system was adjusted to 8-8.5 using NaOH solution. The reaction was maintained under ice bath conditions for 2 h, and then transferred to 4℃ environment and stirred overnight. The resulting reaction solution was dialyzed with deionized water for 5 days and then freeze-dried to obtain HAMA.

[0057] (2) Preparation of drug-loaded hydrogel micronuclei: 40 mg HAMA, 1 mmol metformin hydrochloride, and 1 mg LAP were added to 1 mL PBS buffer and stirred until completely dissolved. The mixture was added to 5 mL of a continuous phase containing 0.25 wt% fluorinated oil surfactant, vortexed for 40 s, sheared to form uniform microdroplets, and irradiated with ultraviolet light for 1 min to induce cross-linking, thus obtaining a physically loaded metformin microgel core.

[0058] (3) The shell preparation steps are the same as in Example 1, and the core-shell hydrogel microspheres with physical drug loading are obtained.

[0059] Characterization results: Figure 9 The in vitro drug release curves for Examples 1 and 4 are shown (test conditions: 37°C, PBS solution with pH=7.4, and shaking on a shaker at 100 rpm): In Example 4, the drug was simply physically encapsulated and was almost completely released on the 3rd day; in Example 1, the drug was bound to the core through dynamic Schiff base bonds, with a sustained release period of up to 14 days, demonstrating that long-term and controllable drug release can be achieved through chemical bonding loading.

[0060] Example 5 The HAMA synthesis and micronucleus preparation steps in this embodiment are the same as in Example 4, except that the concentration of SBMA in the shell-shell mixture is adjusted to 10 w / v%. The other preparation parameters are the same as in Example 4.

[0061] Characterization results: Figure 10 The friction performance test curves for the microspheres (test conditions: Bruker tribometer reciprocating mode, friction distance 4 mm, slider speed 1 mm / s, loading force 2 N, continuous friction for 10 min): The friction coefficients of all hydrogel microsphere groups were lower than those of the pure PBS control group. Among them, the friction coefficient of the core-shell structure microspheres was significantly lower than that of the shell-less pure core microspheres. The friction coefficient of Example 5 was lower than that of Example 4, proving that increasing the SBMA content can increase the density of hydrophilic side chains on the surface of the microspheres, forming a more stable and dense hydration layer, and further enhancing the lubrication performance. Specifically, SBMA contains quaternary ammonium salt groups and sulfonate groups, which can form strong electrostatic-dipole interactions with water molecules, causing the material surface to adsorb a large amount of stable bound water, thereby forming a dense hydration layer. During joint friction, water molecules in this strongly hydrated structure are difficult to compress or squeeze out. During friction, shearing mainly occurs between hydration layers, rather than between solid surfaces, thus significantly reducing the friction coefficient. PEGDA segments have strong hydrophilicity and can further adsorb water molecules, thereby enhancing the hydration state of the material surface. Furthermore, PEGDA has a certain degree of flexibility and can undergo slight deformation during friction, thereby dispersing contact stress and reducing direct contact between solid interfaces.

[0062] Example 6 The remaining preparation steps in this embodiment are the same as in Example 1, except that two immersion parameters in the shell preparation process are adjusted: the immersion time of the micronucleus in the LAP initiator solution is 70 s, and the standing time in the shell mixture solution is 50 s.

[0063] Characterization results: Figure 11 The image shows the particle size distribution of the microspheres prepared in Example 6. The average particle size is 115.85 ± 15.29 μm, which is an increase compared to Example 1. This demonstrates that the shell thickness can be controlled by adjusting the soaking time of the initiator and shell solution, thereby adapting to different degradation cycles and drug release requirements.

[0064] Example 7 The core-shell hydrogel microspheres prepared in Example 1 were used to treat a rat model of osteoarthritis induced by monoiodoacetic acid (MIA): Four 8-week-old SD rats were used in each group. The model was established by intra-articular injection of 50 μL of 2 mg / mL MIA solution. Treatment began 3 days after model establishment. The treatment group received intra-articular injection of 50 μL of core-shell hydrogel microsphere suspension, while the control group received an equal volume of PBS. Treatment was administered once every 2 weeks for a total of 4 weeks. Samples were taken after 8 weeks of treatment for histological staining to evaluate the treatment effect.

[0065] result: Figure 12The results of joint histological staining showed that the articular cartilage in the PBS control group was significantly damaged, with the cartilage layer becoming significantly thinner and a large amount of matrix lost; the cartilage in the core-shell microsphere treatment group showed no obvious cracks or structural damage, proving that the self-lubricating drug-loaded core-shell hydrogel microspheres of this application have a significant therapeutic effect on osteoarthritis.

[0066] In summary, the self-lubricating and degradation-resistant hydrogel core-shell microspheres provided in this application, as clearly shown by the degradation curve, completely degrade the pure hyaluronic acid micronucleus without shell protection within 5 days, which is basically consistent with the in vivo retention period of 1-3 days for existing clinical hyaluronic acid injections. However, the degradation period of the single-shell core-shell microspheres in this application can be extended to 28 days, which is 5-6 times that of pure hyaluronic acid materials. The degradation rate of the double-shell structure microspheres is even slower, which can support a longer in vivo effect, directly solving the core pain point of short retention time and frequent administration required by existing intra-articular injection materials. Its anti-degradation mechanism can be verified by laser confocal microscopy characterization. The completely encapsulated zwitterionic-PEGDA copolymer shell has a dual barrier function of physically blocking enzyme penetration and resisting enzymatic degradation. At the same time, the shell thickness can be flexibly customized by adjusting the vortex time, shell soaking time, and number of shell layers, matching the degradation period of 1 week to 2 months as needed, and adapting to the treatment needs of different disease stages. Based on this, the long-lasting anti-degradation properties can synergize with the low-friction lubrication characteristics and dynamic bond drug sustained-release function of the microspheres, which can not only ensure the continuous joint lubrication effect for more than 28 days, but also match the drug sustained-release cycle of 14 to 28 days, avoiding the risk of drug burst release. Finally, in animal experiments, it was verified that only once every 2 weeks of administration is needed to achieve excellent osteoarthritis treatment effect, which greatly improves patient compliance and clinical treatment benefits.

[0067] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A self-lubricating, degradation-resistant hydrogel core-shell microsphere, characterized in that, Includes kernel and shell; The core is a gel micronucleus formed by photocuring monomers through photocrosslinking; The gel micronuclei are loaded with drugs; The shell layer is a lubricating and anti-degradation layer formed by photocrosslinking polymerization of a hydrophilic zwitterionic polymer and polyethylene glycol diacrylate. The kernel has a particle size of 45~280μm, and the shell has a thickness of 0.1~20μm.

2. The self-lubricating and degradation-resistant hydrogel core-shell microspheres according to claim 1, characterized in that, The photocurable monomer is selected from at least one of modified hyaluronic acid and modified gelatin; The hydrophilic zwitterionic polymer is selected from at least one of methacryloyl ethyl sulfobetaine and carboxybetaine methacrylate.

3. The self-lubricating and degradation-resistant hydrogel core-shell microspheres according to claim 2, characterized in that, The drug is selected from at least one of diclofenac sodium, dexamethasone, ibuprofen, dopamine, resveratrol, curcumin, metformin, Kartogenin, growth factors, and nanoparticles.

4. The self-lubricating and degradation-resistant hydrogel core-shell microspheres according to claim 2, characterized in that, The modification method of the modified hyaluronic acid includes any one of carbon-carbon double bond modification, aldehyde modification, aldehyde-carbon-carbon double bond double modification, carbon-carbon double bond-dopamine double modification, and carbon-carbon double bond-phenylboronic acid double modification. The modified hyaluronic acid has a molecular weight of 50-120 kDa, and the modified gelatin has a molecular weight of 100-200 kDa.

5. A method for preparing self-lubricating and degradation-resistant hydrogel core-shell microspheres, characterized in that, Includes the following steps: S1. Dissolve the photocurable monomer in PBS buffer, stir well, add at least one drug, then add the first photoinitiator, mix well to obtain the hydrogel precursor; S2. Add the hydrogel precursor to the continuous phase, vortex for 20~120s, and then obtain gel micronuclei by photo-induced polymerization. S3. Dissolve the second photoinitiator in PBS buffer to obtain a photoinitiator solution, and then immerse the gel micronucleus in the photoinitiator solution for 30s~120s to allow the second photoinitiator to diffuse to the surface of the gel micronucleus and obtain the microgel core. S4. Add the hydrophilic zwitterionic polymer and polyethylene glycol diacrylate to PBS buffer and mix to obtain a mixed solution; S5. The microgel core is transferred to a mixed solution and left to stand for 30-120 seconds. After in-situ photopolymerization, the microgel core-shell microspheres are collected and washed to obtain the self-lubricating and degradation-resistant hydrogel core-shell microspheres.

6. The method for preparing self-lubricating and degradation-resistant hydrogel core-shell microspheres according to claim 5, characterized in that, In step S1, the amount of the photocurable monomer added is 2-20 w / v% of the PBS buffer volume. The amount of the first photoinitiator added is 0.1~0.5 w / v of the PBS buffer volume; the first photoinitiator is selected from Irgacure 2959 or lithium phenyl-2,4,6-trimethylbenzoylphosphonate.

7. The method for preparing self-lubricating and degradation-resistant hydrogel core-shell microspheres according to claim 5, characterized in that, In step S2, the volume ratio of the hydrogel precursor to the continuous phase is 1:(5~8), and the continuous phase is a mixture of fluorinated oil and emulsifier; The emulsifier is FluoSurf 2 wt.% in Fluo-Oil 7500 fluorinated oil solution, and the content of the emulsifier in the continuous phase is 0.2%~0.4%; In steps S2 and S5, the curing time under light is 30~120s.

8. The method for preparing self-lubricating and degradation-resistant hydrogel core-shell microspheres according to claim 5, characterized in that, In step S3, the amount of the second photoinitiator added is 1 to 5 w / v% of the PBS buffer volume, and the second photoinitiator may be the same as or different from the first photoinitiator.

9. In the method for preparing self-lubricating and anti-degradation hydrogel core-shell microspheres according to claim 5, in step S4, the amount of hydrophilic zwitterionic polymer added is 5-15 w / v of the PBS buffer volume, and the amount of polyethylene glycol diacrylate added is 10-20 w / v of the PBS buffer volume.

10. The application of the self-lubricating and degradation-resistant hydrogel core-shell microspheres according to any one of claims 1 to 4, or the self-lubricating and degradation-resistant hydrogel core-shell microspheres prepared by the preparation method according to any one of claims 5 to 9, characterized in that, Used to prepare preparations for the treatment of osteoarthritis, rheumatoid arthritis, articular cartilage repair, joint lubrication, or long-acting drug delivery carriers.

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