Core-shell structure microgel system as well as preparation method and application thereof

Abstract

The invention provides a core-shell structure microgel system. The core-shell structure microgel system comprises a core and a shell coating the core, the core is composed of a composite hydrogel of methacrylated gelatin and methacrylated chitosan; the shell is formed by double crosslinking of polyethylene glycol diacrylate and alginate. The core serves as a functional core, provides a highly simulated natural extracellular matrix and maintains pancreas islet activity, and the shell serves as a barrier to protect the core, regulate material exchange and provide mechanical support. The core-shell structure microgel system allows diffusion of glucose, oxygen and insulin and blocks immune globulin, cell factors and immune cells, so that fibrosis wrapping is reduced to the greatest extent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of biomedical materials, in particular to a core-shell structure microgel system and a preparation method and application thereof. BACKGROUND

[0002] Type 1 diabetes mellitus (T1DM) is an autoimmune disease in which pancreatic beta cells are destroyed, leading to absolute insulin deficiency. Current clinical management relies on exogenous insulin injections, but this cannot mimic the natural glucose-responsive secretion of healthy beta cells. Therefore, patients are continuously at risk of severe hypoglycemia, vascular complications, and reduced quality of life.

[0003] Restoring endogenous insulin secretion through islet transplantation has become a potential curative therapy. However, its widespread clinical application is hindered by two major obstacles: immune rejection, which requires systemic immunosuppression but carries associated risks; and insufficient long-term survival of transplanted islets due to hypoxia, inflammatory response, and fibrotic encapsulation.

[0004] However, encapsulation technologies for islet transplantation have been extensively explored to provide immune isolation, allowing the diffusion of glucose, oxygen, and insulin, while blocking immune cells and antibodies. However, natural polymer microencapsulation (such as alginate) can trigger a foreign body response, synthetic polymer microencapsulation can lack long-term biostability, and large-volume encapsulation systems have problems of diffusion limitation and poor vascularization. To address the above problems, Lim and Sun developed an alginate-poly-L-lysine-alginate (APA) microgel system to encapsulate islets within the microgel system to shield against immune attack while allowing the diffusion of essential molecules.

[0005] However, the above-mentioned microgel system still has problems of molecular diffusion limitation, severe fibrotic encapsulation, and poor vascularization. SUMMARY

[0006] The present application aims to provide a core-shell structure microgel system and a preparation method and application thereof, to solve the problems of molecular diffusion limitation, severe fibrotic encapsulation, and poor vascularization of the core-shell structure microgel system for long-term immune-isolated islet transplantation.

[0007] To solve the above problems, the present application provides a core-shell structure microgel system, comprising a core and a shell covering the core; the core is composed of a methacrylated gelatin and a methacrylated chitosan composite hydrogel; the shell is formed by double cross-linking of polyethylene glycol diacrylate and alginate.

[0008] The technical effects achieved after the technical scheme are as follows: the core-shell structure microgel system provided by the application is composed of a core and a shell. The core serves as a functional core and is composed of methacrylated gelatin (GelMA) and methacrylated chitosan (CSMA), and is mainly responsible for providing a highly simulated natural extracellular matrix and maintaining the viability of islets. The shell serves as a barrier and is composed of polyethylene glycol diacrylate (PEGDA) and alginate, and is mainly responsible for protecting the core, regulating material exchange and providing mechanical support. The core-shell structure microgel system allows the diffusion of glucose, oxygen and insulin, while blocking immunoglobulins, cytokines and immune cells, thereby minimizing fibrotic encapsulation. The synergistic effect of the core and the shell enables the system to maintain the viability and glucose responsiveness of transplanted islets for more than 60 days without the need for immunosuppression, successfully restores normal blood glucose levels, and its support for minimally invasive subcutaneous implantation exhibits higher safety and clinical application potential compared to traditional portal vein infusion methods.

[0009] Further, the shell has semi-permeability, allowing molecules with a molecular weight of not more than 10 kDa to diffuse through, and preventing molecules with a molecular weight of not less than 40 kDa from diffusing through.

[0010] The technical effects achieved after the technical scheme are as follows: by imparting specific semi-permeability to the shell, the application allows molecules ≤10 kDa to pass through and prevents molecules ≥40 kDa from passing through, successfully constructing a size-selective physical barrier that allows water, ions, glucose, amino acids and other small molecule nutrients and metabolic waste to freely enter and exit, ensuring the normal physiological metabolism and survival of internal bioactive substances. At the same time, the shell can effectively prevent the entry of antibodies, complement proteins and immune cells. This avoids the recognition and removal of internal xenogeneic / allogeneic cells, proteins, etc. by the immune system, thereby eliminating or reducing the use of immunosuppressants, greatly improving the biocompatibility and long-term survival rate and stability of implants or drugs in the body.

[0011] Further, the diameter of the core is 200µm~500µm, and the thickness of the shell is 5µm~50µm.

[0012] The technical effects achieved after the technical scheme are as follows: a core diameter of 200µm to 500µm provides sufficient internal space to encapsulate a large amount of bioactive substances, and compared with nanoscale carriers, the encapsulation efficiency and effective payload per unit volume are significantly improved, thereby being able to produce a biological effect that reaches a therapeutic threshold (such as secreting sufficient insulin). A shell thickness of 5µm~50µm provides sufficient mechanical strength for the core-shell structure microgel system, enabling it to withstand physical stress (such as shear force and osmotic pressure change) during preparation, storage, injection and after implantation in the body, effectively preventing rupture and ensuring the integrity of the immunological isolation barrier.

[0013] Furthermore, the core has a porous structure.

[0014] The technical effects achieved by adopting this solution are as follows: The porous structure constructs an interconnected network of microchannels within the core, significantly shortening the effective diffusion distance of molecules from the shell to the deepest cells, and substantially improving the efficiency of material exchange. This ensures the long-term high survival rate and physiological function of cells within the entire core-shell microgel system. Furthermore, the porous structure physically mimics the extracellular matrix in natural tissues, providing space for cell attachment, extension, and three-dimensional growth. The porous structure further endows the core with a degree of flexibility and compressibility. When the microgel system is subjected to pressure from external tissues, this porous network acts like a sponge, buffering, dispersing, and absorbing stress, preventing the direct transfer of mechanical force to fragile cells, thereby improving the mechanical stability of cells in vivo.

[0015] Furthermore, alginate includes at least one of sodium alginate, calcium alginate, potassium alginate, and chemically modified alginate derivatives.

[0016] The technical effects achieved by adopting this solution are as follows: Alginate is a polysaccharide derived from natural seaweed, whose chemical structure is similar to glycosaminoglycans in the human body and exhibits extremely low immunogenicity. As a shell material, it can minimize the host's foreign body reaction and the formation of fibrotic capsules after implantation. This is crucial for cell encapsulation that requires long-term in vivo function (such as in the treatment of diabetes), as excessive fibrosis can hinder substance exchange and ultimately lead to the failure of encapsulated cells. Natural alginate can be slowly degraded in vivo, and its degradation products are non-toxic and can be excreted through normal metabolic pathways. By chemically modifying alginate derivatives, its degradation rate can be precisely controlled to match the needs of different therapeutic scenarios.

[0017] This invention also provides a method for preparing a core-shell structured microgel system, which can prepare a core-shell structured microgel system as described above, and the preparation method includes: S1: Prepare a core prepolymer solution containing methacrylamide gelatin and methacrylamide chitosan; S2: Prepare a shell prepolymer solution containing polyethylene glycol diacrylate and alginate; S3: Using droplet microfluidics, a core structure droplet is generated by using a core prepolymer liquid as the inner phase and liquid paraffin as the outer phase. S4: Irradiate the core structure droplets with ultraviolet light to cause photocrosslinking of the core prepolymer liquid, thereby obtaining a core structure microgel system; S5: Immerse the core structure microgel system in a solution containing cationic initiators and photoinitiators to attach cationic initiators and photoinitiators to the surface of the core structure microgel system, thereby obtaining a modified core structure microgel system; S6: The modified core-shell microgel system is immersed in the shell prepolymer solution and then irradiated with ultraviolet light to obtain the core-shell microgel system.

[0018] The technical effects achieved by adopting this solution are as follows: By employing droplet microfluidics and precisely controlling the flow rate ratio of the core prepolymer solution, the size of the core can be precisely controlled. This results in a core-structured microgel system with highly consistent morphology and size. Methacrylamide gelatin (GelMA) and methacrylamide chitosan (CSMA) in the core prepolymer solution undergo cross-linking under ultraviolet light, rapidly forming a stable and elastic three-dimensional network gel. Immersing the modified core-structured microgel system in the outer shell prepolymer solution ultimately forms a more stable core-shell microgel system with mechanical support. By precisely controlling the immersion time or the number of cycles, the thickness of the outer shell can be precisely controlled, enabling complex functions and intelligent responses that are impossible with a single material.

[0019] Further, in step S5, the number of soakings is 1 to 3 times, and the soaking time is 5 min to 30 min; and / or in step S6, the number of soakings is 1 time, and the soaking time is 1 min to 5 min; the ultraviolet light irradiation time is 30 s to 180 s.

[0020] The technical effects achieved by adopting this solution are as follows: By controlling the immersion time and number of times the core structure microgel system is immersed in a solution containing cationic initiators and photoinitiators, it is ensured that the cationic initiator and photoinitiator solutions can fully penetrate and uniformly adsorb onto the surface and pore network of the core structure microgel system, avoiding insufficient initiator loading and uneven distribution caused by a single short immersion. By controlling the immersion time of the modified core structure microgel system in the shell prepolymer solution, the thickness of the shell can be precisely controlled. By controlling the ultraviolet light irradiation time, the problems of insufficient cross-linking degree and loose structure of the shell caused by too short an irradiation time are avoided, while damage to the core and excessive cross-linking of the shell caused by too long an irradiation time are avoided.

[0021] Furthermore, the cationic initiator includes at least one of calcium chloride, barium chloride, and strontium chloride; and / or the photoinitiator includes lithium phenyl (2,4,6-trimethylbenzoyl) phosphate.

[0022] The technical effects achieved by adopting this technical solution are as follows: The cationic initiator is selected from divalent cations such as calcium chloride, barium chloride, and strontium chloride, which can undergo efficient ionic cross-linking with alginate in the shell prepolymer solution; The photoinitiator is selected from lithium phenyl (2,4,6-trimethylbenzoyl) phosphate, which has excellent biocompatibility and extremely low cytotoxicity. After the cross-linking reaction is efficiently initiated under ultraviolet light irradiation, its decomposition products have minimal interference with the cell microenvironment.

[0023] The present invention also provides an application of the core-shell structured microgel system as described above, using the core-shell structured microgel system to treat type 1 diabetes.

[0024] Pancreatic islets are encapsulated in a core-shell microgel system. The core provides a biomimetic extracellular matrix environment for the islet cells, maintaining their viability. The shell allows small molecules such as glucose, oxygen, and nutrients to enter, maintaining the survival and function of the encapsulated islets. It also allows the secretion of hormones such as insulin and glucagon, responsively regulating blood glucose levels and effectively blocking the invasion of large molecules (such as antibodies and complement proteins) and immune cells (such as T cells and macrophages) from the host immune system. This method can maintain the viability and glucose responsiveness of transplanted islets for over 60 days without immunosuppression, successfully restoring normal blood glucose levels.

[0025] The present invention also provides a smart device, which is a biosensor for glucose / oxygen monitoring that embeds a core-shell structured microgel system as described above.

[0026] The technical effects achieved by adopting this solution are as follows: The problem of signal attenuation and shortened lifespan caused by foreign body reaction in implantable biosensors is solved by embedding a biosensor for glucose / oxygen monitoring into a core-shell structured microgel system. This transforms the sensor from a "foreign object" rejected by the body into a biointegrated system that can "coexist harmoniously" with surrounding tissues, thereby achieving long-term, stable and accurate in vivo monitoring.

[0027] By adopting the technical solution of the present invention, the following technical effects can be achieved: (1) Durable immune isolation and shielding: This core-shell structured microgel system has a precise molecular sieve function. Its 40kDa molecular retention pore size can effectively block the invasion of macromolecular immune effectors such as antibodies and pro-inflammatory cytokines, fundamentally preventing immune rejection reactions against internal functional cells and providing them with a safe "immune exemption" microenvironment. (2) Excellent anti-fibrotic and immunomodulatory capabilities: This core-shell microgel system can effectively inhibit the non-specific adsorption of proteins and the adhesion of immune cells, which blocks the initiation of foreign body reaction from the source, thereby significantly reducing or avoiding the formation of fibrotic capsules and ensuring a long-term material exchange channel between the device and the host tissue. (3) Ensure the long-term stability and activity of the core functional unit: The islets encapsulated by this core-shell structure microgel system can maintain structural integrity and exhibit the physiological function of continuous insulin secretion for more than 60 days, thus achieving long-term therapeutic effect. (4) Promotes angiogenesis and host tissue integration; This core-shell microgel system can more actively induce the formation of new blood vessels around the implantation site and promote good integration with the host tissue. (5) Convenient and safe clinical application mode: The core-shell structured microgel system is delivered by subcutaneous implantation, which has the advantages of being minimally invasive, easy to remove and simple to operate, providing higher safety and flexibility for clinical treatment; (5) Highly controllable large-scale production capability: The use of microfluidic technology ensures the high consistency and reproducibility of the size and morphology of the core-shell structured microgel system. Attached Figure Description

[0028] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a flowchart of the preparation method of the core-shell structured microgel system provided in the embodiments of the present invention; Figure 2 This is a SEM image of the core-shell structured microgel provided in Embodiment 1 of the present invention; Figure 3 This is an adhesion diagram of macrophages in the core-shell structured microgel system prepared in Example 1 of the present invention; Figure 4 This is an adhesion diagram of T cells in the core-shell structured microgel system prepared in Example 1 of the present invention; Figure 5 This is an adhesion diagram of fibroblasts in the core-shell structured microgel system prepared in Example 1 of the present invention; Figure 6 This is a survival image of the encapsulated pancreatic islet cells prepared in Example 2 of the present invention; Figure 7 This is a diagram of insulin secretion from encapsulated pancreatic islet cells prepared in Example 2 of the present invention; Figure 8 This is a blood glucose maintenance diagram of a core-shell microgel system implanted subcutaneously in Embodiment 3 of the present invention; Figure 9 This is a diagram illustrating angiogenesis when a core-shell microgel system is implanted subcutaneously in Embodiment 3 of the present invention. Detailed Implementation

[0029] To make the above-mentioned objectives, features, and advantages of the present invention more apparent and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] The present invention provides a core-shell structured microgel system, comprising a core and a shell covering the core; the core is composed of a composite hydrogel of methacrylamide gelatin and methacrylamide chitosan; the shell is formed by double crosslinking of polyethylene glycol diacrylate and alginate.

[0031] This embodiment provides a core-shell structured microgel system consisting of a core and an outer shell. The core, as the functional core, is primarily responsible for providing a highly simulated natural extracellular matrix to maintain pancreatic islet activity. This is due to the retention of the arginine-glycine-aspartic acid sequence in natural gelatin by GelMA, a key site for cell recognition and adhesion. CSMA possesses natural antibacterial properties, good biocompatibility, and degradability. The outer shell, acting as a barrier, is primarily responsible for protecting the core, regulating substance exchange, and providing mechanical support. PEGDA exhibits high bioinertness, effectively resisting protein adsorption and cell adhesion, while alginate demonstrates excellent biocompatibility and its mild ionic cross-linking properties are very cell-friendly. This core-shell synergy enables the system to maintain the viability and glucose responsiveness of transplanted islets for more than 60 days without immunosuppression and successfully restore normal blood glucose levels. Furthermore, its support for minimally invasive subcutaneous implantation demonstrates higher safety and clinical application potential compared to traditional portal vein infusion.

[0032] In some embodiments of this application, the shell of the core-shell structured microgel system is semi-permeable, allowing molecules with a molecular weight not greater than 10 kDa to diffuse through, while preventing molecules with a molecular weight not less than 40 kDa from diffuse through.

[0033] By endowing the shell of the core-shell microgel system with specific semi-permeability, allowing molecules ≤10 kDa to pass through while blocking molecules ≥40 kDa, a size-selective physical barrier was successfully constructed. This barrier allows small molecule nutrients such as water, ions, glucose, and amino acids, as well as metabolic waste, to freely enter and exit, ensuring the normal physiological metabolism and survival of internal bioactive substances. Simultaneously, the shell effectively prevents the entry of antibodies, complement proteins, and immune cells. This avoids the recognition and clearance of internal xenogeneic / allogeneic cells and proteins by the immune system, thus eliminating or reducing the need for immunosuppressants and significantly improving the biocompatibility and long-term survival and stability of implants or drugs in vivo.

[0034] In some embodiments of this application, the core of the core-shell structured microgel system has a diameter of 200µm to 500µm, and the outer shell of the core-shell structured microgel system has a thickness of 5µm to 50µm.

[0035] By precisely controlling the dimensions of the core and shell of the core-shell microgel system, the synergistic optimization of structure and function has been further achieved. The core diameter of 200µm to 500µm provides sufficient internal space to encapsulate a large amount of bioactive substances. Compared with nanoscale carriers, its encapsulation efficiency and effective load per unit volume are significantly improved, thereby generating biological effects that reach therapeutic thresholds, such as sufficient insulin secretion. The shell thickness of 5µm to 50µm provides sufficient mechanical strength for the core-shell microgel system, enabling it to withstand physical stresses (such as shear forces and osmotic pressure changes) during preparation, storage, and injection, as well as compression after implantation, effectively preventing rupture and ensuring the integrity of the immune barrier.

[0036] In some embodiments of this application, the core of the core-shell structured microgel system has a porous structure.

[0037] The porous structure constructs an interconnected network of microchannels within the core, significantly shortening the effective diffusion distance of molecules from the shell to the deepest cells, thus greatly improving the efficiency of substance exchange. This ensures the long-term high survival rate and physiological function of cells within the entire core-shell microgel system. Furthermore, the porous structure physically mimics the extracellular matrix in natural tissues, providing space for cell attachment, extension, and three-dimensional growth. The porous structure further endows the core with a degree of flexibility and compressibility. When the microgel system is subjected to pressure from external tissues, this porous network acts like a sponge, cushioning and dispersing stress, preventing the direct transfer of mechanical force to fragile cells, thereby improving the mechanical stability of cells in vivo.

[0038] In some embodiments of this application, alginate includes at least one of sodium alginate, calcium alginate, potassium alginate, and chemically modified alginate derivatives. Alginate is a polysaccharide derived from natural seaweed, whose chemical structure is similar to glycosaminoglycans in the human body and exhibits extremely low immunogenicity. As a shell material, it minimizes the host's foreign body reaction and the formation of fibrotic capsules after implantation. This is crucial for cell encapsulation that requires long-term in vivo function (such as in diabetes treatment), as excessive fibrosis can hinder substance exchange, ultimately leading to cell failure. Natural alginate degrades slowly in vivo, and its degradation products are non-toxic and can be excreted through normal metabolic pathways. By chemically modifying alginate derivatives, its degradation rate can be precisely controlled to meet the needs of different therapeutic scenarios.

[0039] Embodiments of the present invention also provide a method for preparing a core-shell structured microgel system, see [link to embodiment]. Figure 1 As shown, this preparation method can prepare core-shell structured microgel systems as described above. The preparation method includes: S1: Prepare a core prepolymer solution containing methacrylamide gelatin and methacrylamide chitosan; S2: Prepare a shell prepolymer solution containing polyethylene glycol diacrylate and alginate; S3: Using droplet microfluidics, a core structure droplet is generated by using a core prepolymer liquid as the inner phase and liquid paraffin as the outer phase. S4: Irradiate the core structure droplets with ultraviolet light to cause photocrosslinking of the core prepolymer liquid, thereby obtaining a core structure microgel system; S5: Immerse the core structure microgel system in a solution containing cationic initiators and photoinitiators to attach cationic initiators and photoinitiators to the surface of the core structure microgel system, thereby obtaining a modified core structure microgel system; S6: The modified core-shell microgel system is immersed in the shell prepolymer solution and then irradiated with ultraviolet light to obtain the core-shell microgel system.

[0040] In the preparation of a core-shell microgel system, droplet microfluidics is employed to precisely control the core size by controlling the flow rate ratio of the core prepolymer solution. This results in a highly consistent morphology and size in the prepared core-shell microgel system. Methacrylamide gelatin (GelMA) and methacryloylchitosan (CSMA) in the core prepolymer solution crosslink under ultraviolet light, rapidly forming a stable and elastic three-dimensional network gel. Immersing the modified core-shell microgel system in the outer shell prepolymer solution ultimately forms a more stable core-shell microgel system with mechanical support. By precisely controlling the immersion time or the number of cycles, the thickness of the outer shell can be precisely controlled, enabling complex functions and intelligent responses that are impossible with a single material.

[0041] In some embodiments of this application, in step S5, the number of soakings is 1 to 3 times, and the soaking time is 5 min to 30 min; and / or in step S6, the number of soakings is 1 time, and the soaking time is 1 min to 5 min, preferably 1 min to 2 min; the ultraviolet light irradiation time is 30 s to 180 s, preferably 60 s to 120 s.

[0042] In the preparation of a core-shell microgel system, by controlling the immersion time and number of times the core microgel system is immersed in a solution containing cationic initiators and photoinitiators, it is ensured that the cationic initiator and photoinitiator solutions can fully penetrate and uniformly adsorb onto the surface and pore network of the core microgel system, avoiding insufficient initiator loading and uneven distribution caused by a single short immersion. By controlling the immersion time of the modified core microgel system in the shell prepolymer solution, the thickness of the shell can be precisely controlled. By controlling the ultraviolet light irradiation time, the problems of insufficient cross-linking degree and loose structure of the shell caused by too short an irradiation time are avoided, while damage to the core and excessive cross-linking of the shell caused by too long an irradiation time are avoided.

[0043] In some embodiments of this application, the cationic initiator includes at least one of calcium chloride, barium chloride, and strontium chloride; and / or the photoinitiator includes lithium phenyl (2,4,6-trimethylbenzoyl) phosphate.

[0044] In the preparation of a core-shell structured microgel system, divalent cations such as calcium chloride, barium chloride, and strontium chloride are selected as cationic initiators, which can undergo efficient ionic crosslinking with alginate in the shell prepolymer solution, preferably calcium chloride; lithium phenyl (2,4,6-trimethylbenzoyl) phosphate is selected as the photoinitiator, which has excellent biocompatibility and extremely low cytotoxicity. After the crosslinking reaction is efficiently initiated under ultraviolet light irradiation, its decomposition products have minimal interference with the cellular microenvironment.

[0045] This invention also provides an application of the core-shell microgel system described above, using the core-shell microgel system to treat type 1 diabetes. Islets are encapsulated in the core-shell microgel system. The core provides a biomimetic extracellular matrix environment for the islet cells, maintaining islet viability. The shell allows small molecules such as glucose, oxygen, and nutrients to enter, maintaining the survival and function of the encapsulated islets, while allowing the secretion of hormones such as insulin and glucagon to responsively regulate blood glucose. It effectively blocks the invasion of macromolecules (such as antibodies and complement proteins) and immune cells (such as T cells and macrophages) from the host immune system. It can maintain the viability and glucose responsiveness of transplanted islets for more than 60 days without immunosuppression and successfully restore normal blood glucose levels.

[0046] Specifically, the islets encapsulated in a core-shell microgel system maintain insulin secretion function for at least 60 days after transplantation. This means that a single transplant can provide at least two months of autonomous blood glucose regulation, freeing diabetic patients from the burden of multiple daily insulin injections and blood glucose monitoring. This not only significantly improves patients' quality of life but also significantly reduces the risk of drastic blood glucose fluctuations due to improper operation or poor adherence.

[0047] Furthermore, when the core-shell microgel system is implanted into the target tissue, its porous core structure mimics the natural extracellular matrix, providing an ideal 3D space and topological guidance for the migration, proliferation, and arrangement of endothelial cells. Cells no longer grow randomly but can "crawl" and organize along the porous structure, forming tubular vascular rudiments. The methacrylated gelatin in the core contains a large number of arginine-glycine-aspartic acid sequences, which are key recognition sites for cell adhesion. Moreover, chitosan and its degradation products have immunomodulatory effects, recruiting immune cells such as macrophages. These recruited cells, in the microenvironment created by the microgel, secrete large amounts of pro-angiogenic growth factors. Therefore, the microgel system acts as a "signal amplifier," utilizing the host's own repair capabilities to provide continuous chemical signal stimulation for angiogenesis.

[0048] This invention also provides a smart device, which is a biosensor for glucose / oxygen monitoring that embeds any of the core-shell structured microgel systems described above.

[0049] One type of intelligent device embeds a core-shell microgel system into a biosensor for glucose / oxygen monitoring. Due to the signal attenuation and shortened lifespan caused by foreign body reactions, implantable biosensors are transformed from a "foreign object" rejected by the body into a biointegrated system that can "coexist harmoniously" with surrounding tissues, thereby achieving long-term, stable, and accurate in vivo monitoring.

[0050] The core-shell microgel system of this invention is not limited to its current applications. In the field of cell therapy, its application can be expanded from allogeneic islet transplantation to xenotransplantation (such as encapsulating porcine islets). Simultaneously, this core-shell microgel system can flexibly encapsulate more types of therapeutic cells, such as parathyroid cells for treating hypoparathyroidism, adrenal cells for treating adrenocortical insufficiency, dopaminergic neurons for treating Parkinson's disease, or hepatocytes for liver function support, thereby extending the therapeutic scope to various endocrine, neurological, and metabolic diseases. Regarding functional enhancement, the system can also co-encapsulate various bioactive molecules to optimize the microenvironment, such as carrying oxygen carriers to alleviate local hypoxia in the early stages of implantation, or releasing angiogenic factors to actively accelerate the integration of the host vascular network. In terms of clinical application pathways, in addition to convenient subcutaneous implantation, implantation can be performed at different sites such as the omentum or intramuscular region, depending on specific treatment needs and anatomical location, or using a catheter-based minimally invasive delivery method, greatly expanding its clinical applicability and potential.

[0051] Example 1 An embodiment of the present invention provides a method for preparing a core-shell structured microgel system, comprising the following steps: S1: Prepare a core prepolymer solution containing methacrylamide gelatin and methacrylamide chitosan; S2: Prepare a shell prepolymer solution containing polyethylene glycol diacrylate and alginate; S3: Using droplet microfluidics, a core structure droplet is generated by using a core prepolymer liquid as the inner phase and liquid paraffin as the outer phase. S4: Irradiate the core structure droplets with ultraviolet light to cause photocrosslinking of the core prepolymer liquid, thereby obtaining a core structure microgel system; S5: The core structure microgel system is immersed in a solution of calcium chloride and lithium phenyl (2,4,6-trimethylbenzoyl) phosphate to attach calcium chloride and lithium phenyl (2,4,6-trimethylbenzoyl) phosphate to the surface of the core structure microgel system, thereby obtaining a modified core structure microgel system; S6: The modified core-shell microgel system is immersed in the shell prepolymer solution and then irradiated with ultraviolet light to obtain the core-shell microgel system.

[0052] In step S5, the soaking is performed twice, with each soaking lasting 10 minutes; in step S6, the soaking is performed once, with each soaking lasting 2 minutes; and the ultraviolet light irradiation time is 90 seconds.

[0053] In Example 1, a core-shell microgel system with a GelMA / CHMA core diameter of 300 µm was prepared and coated with a 15 µm PEGDA / alginate shell. The core-shell microgel system prepared in Example 1 has a porous structure, as shown in Figure 2.

[0054] The molecular permeability of the core-shell structured microgel system prepared in Example 1 was tested, and the test results are shown in Table 1.

[0055] Table 1. Results of molecular permeability testing of core-shell structured microgel systems Molecular permeability tests on the core-shell microgel system show that it allows molecules with a molecular weight not greater than 10 kDa to diffuse through, but prevents molecules with a molecular weight not less than 40 kDa from diffusing through.

[0056] Comparative Example 1 S1: Prepare the core prepolymer solution of GelMA and CHMA; S2: Using droplet microfluidic technology, the core prepolymer liquid is generated into core droplets; S3: Irradiate the core droplet with ultraviolet light to cause photocrosslinking of the core prepolymer liquid, resulting in a microgel system with only the core.

[0057] The core-shell microgel system prepared in Example 1 and the core-only microgel system prepared in Comparative Example 1 were co-cultured with macrophages, T cells, and fibroblasts, respectively. Figure 3 It is evident that the core-shell microgel system prepared in Example 1 significantly reduced macrophage adhesion. From Figure 4 It is evident that the core-shell microgel system prepared in Example 1 significantly reduced T cell adhesion. From Figure 5 It is evident that the core-shell structured microgel system prepared in Example 1 significantly reduced fibroblast adhesion.

[0058] Example 2 This invention provides an application of a core-shell microgel system for the treatment of type 1 diabetes. Pancreatic islets are encapsulated within the core-shell microgel system. Figure 6 It can be seen that the pancreatic islet cells encapsulated in Example 2 can survive stably for a long time, and their viability remains greater than 80% on day 60. Figure 7 It can be seen that the islets encapsulated in Example 2 exhibit long-term glucose-responsive insulin secretion.

[0059] Example 3 An embodiment of the present invention provides an application of a core-shell structured microgel system, in which the system is subcutaneously implanted into STZ-induced diabetic rats, maintaining normal blood glucose levels for 60 days; angiogenesis is confirmed by CD31 staining. Figure 8 As can be seen, in Example 3, after subcutaneous implantation of the core-shell microgel system, normal blood glucose levels were maintained for 60 days. From Figure 9 As can be seen, after subcutaneous implantation of the core-shell microgel system in Example 3, CD31 confirmed angiogenesis.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A core-shell microgel system, characterized in that, comprise a core and a shell covering the core; the core is composed of a methacrylated gelatin and a methacrylated chitosan composite hydrogel; the shell is formed by double crosslinking of polyethylene glycol diacrylate and alginate.

2. The core-shell microgel system according to claim 1, wherein, the shell has semi-permeability, allowing molecules with a molecular weight of no more than 10 kDa to diffuse through, and preventing molecules with a molecular weight of no less than 40 kDa from diffusing through.

3. The core-shell microgel system according to claim 1, wherein, the diameter of the core is 200 µm to 500 µm, and the thickness of the shell is 5 µm to 50 µm.

4. The core-shell microgel system according to claim 1, wherein, the core has a porous structure.

5. The core-shell microgel system according to claim 1, wherein, the alginate comprises at least one of sodium alginate, calcium alginate, potassium alginate, and a chemically modified alginate derivative.

6. A method for the preparation of a core-shell microgel system according to any one of claims 1 to 5, characterized in that the preparation method comprises: S1: preparing a core prepolymer solution comprising the methacrylated gelatin and the methacrylated chitosan; S2: preparing a shell prepolymer solution comprising the polyethylene glycol diacrylate and the alginate; S3: using a droplet microfluidic technique, taking the core prepolymer solution as the internal phase and liquid paraffin as the external phase to generate core structure droplets; S4: irradiating the core structure droplets with ultraviolet light to cause photo-crosslinking of the core prepolymer solution, thereby obtaining the core structure microgel system; S5: immersing the core structure microgel system in a solution containing a cationic initiator and a photoinitiator, so that the cationic initiator and the photoinitiator adhere to the surface of the core structure microgel system, thereby obtaining a modified core structure microgel system; S6: immersing the modified core structure microgel system in the shell prepolymer solution and irradiating it with ultraviolet light, thereby obtaining the core-shell structure microgel system.

7. The production method according to claim 6, wherein in the step S5, the number of immersions is 1 to 3, and the immersion time is 5 min to 30 min; and / or in the step S6, the number of immersions is 1, the immersion time is 1 min to 5 min, and the ultraviolet irradiation time is 30 s to 180 s.

8. The preparation method according to claim 6, characterized in that, the cationic initiator comprises at least one of calcium chloride, barium chloride, and strontium chloride; and / or the photoinitiator comprises a phenyl (2,4,6-trimethylbenzoyl) lithium phosphate salt.

9. Use of a core-shell microgel system according to any one of claims 1 to 5, characterized in that the core-shell structure microgel system is used for treating type I diabetes.

10. An intelligent equipment, characterized by, the intelligent equipment is a biosensor for glucose / oxygen monitoring in which the core-shell structure microgel system of any one of claims 1 to 5 is embedded.

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