Intelligent glucose-responsive microneedle tube and preparation method and application thereof

Abstract

The application discloses an intelligent glucose-responsive microneedle tube and a preparation method and application thereof. The intelligent glucose-responsive microneedle tube comprises a needle body shell with a cavity structure and a drug wrapped in the cavity structure, and specifically, oxidized dextran is prepared by combining dextran and sodium periodate, then dopamine hydrochloride is added to prepare oxidized dextran grafted with dopamine, benzene boronic acid group compound and ethylene glycol chitosan are used to prepare ethylene glycol chitosan grafted with benzene boronic acid, then the two intermediate products are mixed to prepare crosslinked hydrogel, the product is prepared by injecting the crosslinked hydrogel into a microneedle mold, adding a drug and drying. The intelligent glucose-responsive cavity needle body with a double-crosslinked gel network base is constructed, blood glucose concentration-dependent insulin intelligent release is realized, the cavity structure with different sizes for drug loading is customized, the drug loading capacity, the controllable insulin release performance and the biocompatibility are improved, and the safety and intelligence of microneedle injection are improved.

Description

Technical Field

[0001] This invention belongs to the field of biomedical materials technology, specifically relating to a smart glucose-responsive microneedle, its preparation method, and its application. Background Technology

[0002] Diabetes is a chronic disease caused by pancreatic damage, leading to persistently high and volatile blood sugar levels. For type 1 and severe type 2 diabetes, the only treatment is external insulin supplementation to regulate blood sugar. Current conventional injection therapy has poor control over insulin release, which can easily lead to hypoglycemia and, in severe cases, endanger the patient's life.

[0003] To improve the controllability and safety of insulin injection therapy, researchers have developed a glucose-responsive microneedle delivery technology to enhance the intelligence of injection treatment. However, during microneedle therapy, the drug release process is often accompanied by the dissolution of the microneedle tip material. This needle material often contains reactants, initiators, and organic solvents added during microneedle manufacturing. Therefore, the dissolution process can also lead to side effects such as inflammation of the skin in the treatment area. To address this dissolution issue, the construction of a composite cross-linking system in the microneedle gel substrate can largely prevent microneedle dissolution.

[0004] However, in existing insulin microneedle injection therapy, the reactants, initiators and organic solvents in the needle material are often easily dissolved, which may cause potential safety issues such as skin inflammation and immune response. Summary of the Invention

[0005] This invention aims to address the safety concerns arising from the dissolution of reactants, initiators, and organic solvents in the needle material during microneedle injection therapy, which could lead to potential skin inflammation and immune system damage. This invention provides a smart glucose-responsive microneedle, its preparation method, and its applications. By constructing a smart glucose-responsive hollow needle with a double-crosslinked gel network base, the aforementioned problems are avoided.

[0006] This invention, by establishing a smart glucose-responsive microneedle, can improve drug loading and controllable insulin release performance. Furthermore, the cavity structure with a smart glucose-responsive mechanism can prevent the needle material from dissolving within the skin, thereby further enhancing the safety and intelligence of microneedle injection therapy.

[0007] This invention enables glucose concentration-dependent intelligent insulin release by regulating the cross-linking sites within the gel that respond to glucose concentration. Furthermore, by adjusting the mixing ratio of the needle gel substrate components, drug-loaded cavity structures of different sizes can be customized.

[0008] The technical solution adopted in this invention is:

[0009] I. A smart glucose-responsive microneedle:

[0010] The microneedle mainly consists of a needle shell with a hollow structure and a drug component. The drug component is encapsulated within the hollow structure of the needle shell. The needle shell with a hollow structure is mainly made of a mixed gel composed of modified polymers. The drug component is a solid powder or a solution.

[0011] The modified polymer is mainly composed of modified ethylene glycol chitosan and modified oxidized dextran, that is, ethylene glycol chitosan grafted with phenylboronic acid and oxidized dextran grafted with dopamine. The mixed gel is the cross-linked hydrogel obtained by the preparation method.

[0012] The microneedle also includes a back patch, which is fixed to the surface of the needle shell. The back patch is mainly made of a solution of natural polymer materials.

[0013] The hollow needle shell, based on a cross-linked gel, provides drug loading capacity and intelligent glucose response. The back patch, made of a natural polymer material, offers good biocompatibility and mechanical strength.

[0014] The drug component is specifically one or more of recombinant human insulin, aspart insulin, glargine insulin, and glucagon-like polypeptide-1, and the amount of drug component added is 0.5-100 IU.

[0015] The natural polymer material mentioned is specifically one or more of hyaluronic acid, collagen, gelatin, and sodium alginate.

[0016] II. A method for preparing a smart glucose-responsive microneedle, the method comprising:

[0017] 1) The compound containing phenylboronic acid groups, ethylene glycol chitosan, and the catalyst were dissolved in solvents to obtain their respective solutions. Then, the three solutions were mixed and reacted to prepare ethylene glycol chitosan grafted with phenylboronic acid.

[0018] 2) Dextran and sodium periodate were dissolved separately in deionized water to obtain their respective solutions, and then the two solutions were mixed and reacted to prepare oxidized dextran;

[0019] 3) Oxidized dextran and dopamine hydrochloride were dissolved separately in deionized water to obtain their respective solutions, and then the two solutions were mixed and reacted to prepare dopamine-grafted oxidized dextran.

[0020] 4) The ethylene glycol chitosan grafted with phenylboronic acid obtained in step 1) and the oxidized dextran grafted with dopamine obtained in step 3) were dissolved in deionized water, and then the two solutions were mixed to prepare a cross-linked hydrogel.

[0021] 5) The cross-linked hydrogel obtained in step 4) is injected into the microneedle mold for centrifugation and drying. Then, drug components are added to it to prepare a drug-loaded needle shell with a cavity structure, which is the smart glucose-responsive microneedle tube.

[0022] Through the above steps, a smart glucose-responsive microneedle is prepared.

[0023] In practice, a layer of natural polymer-based aqueous solution can be added to the back to form a back patch. After drying again, a smart glucose-responsive microneedle can be prepared.

[0024] The back patch is formed by coating or spraying with a natural polymer-based aqueous solution at a concentration of 300 mg / mL.

[0025] Specifically, step 1) involves:

[0026] 1.1) A mixed solution A is prepared by dissolving a compound containing phenylboronic acid groups together with ethylene glycol chitosan in a solvent;

[0027] 1.2) Dissolve the catalyst in a solvent to prepare mixed solution B;

[0028] 1.3) Pour mixed solution B into mixed solution A and stir for a certain period of time to obtain the solution after the first reaction;

[0029] 1.4) The solution after the first reaction was subjected to dialysis and freeze-drying in sequence to prepare ethylene glycol chitosan grafted with phenylboronic acid.

[0030] Step 1) can also be specifically described as follows:

[0031] 1.1) The compound containing phenylboronic acid groups, ethylene glycol chitosan, and the catalyst are dissolved in solvents to form their respective solutions;

[0032] 1.2) Pour the catalyst solution into the solution of the compound containing phenylboronic acid groups, then pour in the ethylene glycol chitosan solution, and stir the reaction for a certain period of time to obtain the solution after the first reaction;

[0033] 1.3) The solution after the first reaction was subjected to dialysis and freeze-drying in sequence to prepare ethylene glycol chitosan grafted with phenylboronic acid.

[0034] In step 1), the amount of compound containing phenylboronic acid group added is 0.01-6g, the amount of ethylene glycol chitosan added is 0.01-6g, the amount of solvent used is 2-100mL, the amount of catalyst used is 20%-80% of the mass of compound containing phenylboronic acid group added, and the amount of catalyst added is 0.002-4.8g.

[0035] In step 1), the compound containing the phenylboronic acid group is specifically one or more of 3-carboxyphenylboronic acid, 4-carboxyphenylboronic acid, 4-carboxyphenylboronic acid pinacol ester, 4-(carboxymethyl)phenylboronic acid pinacol ester, and 4-carboxy-2-fluorophenylboronic acid pinacol ester; the catalyst specifically includes one or more of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride EDC and N-hydroxysuccinimide NHS; the solvent is one or more of deionized water, methanol, isopropanol, anhydrous ethanol, dimethyl sulfoxide, and N,N-dimethylformamide.

[0036] The compounds containing phenylboronic acid groups, ethylene glycol chitosan, and catalysts all use the same solvent.

[0037] Step 2) specifically refers to:

[0038] 2.1) Dissolve dextran of different molecular weights in deionized water to prepare mixed solution C;

[0039] 2.2) Dissolve sodium periodate in deionized water to prepare mixed solution D;

[0040] 2.3) Pour mixed solution D into mixed solution C and stir for a certain period of time to obtain the second reaction solution;

[0041] 2.4) The solution after the second reaction was subjected to dialysis and freeze-drying in sequence to prepare oxidized dextran;

[0042] In step 2), the molecular weight of the dextran is 30,000 to 100,000, the amount of dextran added is 0.01-5g, and the amount of sodium periodate added is 0.01-5g.

[0043] Step 3) specifically refers to:

[0044] 3.1) Dissolve oxidized dextran in deionized water to prepare mixed solution E;

[0045] 3.2) Dissolve dopamine hydrochloride in deionized water to prepare a mixed solution F;

[0046] 3.3) Pour mixed solution F into mixed solution E and stir for a certain period of time to obtain the third reaction solution;

[0047] 3.4) The solution after the third reaction was subjected to dialysis and freeze-drying in sequence to prepare dopamine-grafted oxidized dextran;

[0048] In step 3), the amount of oxidized dextran added is 0.01-5g, and the amount of dopamine hydrochloride added is 0.01-5g.

[0049] In steps 1), 2), and 3), the reaction temperature is 5-25℃ and the reaction time is 1-48 hours; preferably, the reaction time is 1-12 hours.

[0050] In step 4), the aqueous solution concentration of ethylene glycol chitosan grafted with phenylboronic acid is 5-500 mg / mL, the aqueous solution concentration of oxidized dextran grafted with dopamine is 5-500 mg / mL, and the volume ratio of the two solutions is 1:3 to 3:1.

[0051] In step 4), the centrifugation process specifically involves centrifuging at 500-4000 rpm for 10-30 minutes; the drying process specifically involves placing the microneedle mold in a desiccator for 6-48 hours, with a drying environment of 10% humidity and 25°C. The two drying processes are identical.

[0052] The present invention relates to the application of the intelligent glucose-responsive microneedle in diabetes pharmaceutical manufacturing, specifically its application in the preparation and release of insulin drugs.

[0053] The intelligent glucose-responsive microneedle of this invention regulates the crosslinking density and solid content of the crosslinked hydrogel, which serves as the needle gel substrate, by adjusting the concentration and addition amount of ethylene glycol chitosan grafted with phenylboronic acid and oxidized dextran grafted with dopamine. This, in turn, regulates the insulin loading and simultaneously adjusts the glucose-sensitive swelling properties of the needle shell, intelligently controlling insulin release. Specifically, at higher insulin concentrations, it autonomously regulates the release of more insulin.

[0054] The intelligent glucose-responsive microneedle of this invention allows for customized insulin loading by adjusting the crosslinking density and solid content of the needle gel substrate. Furthermore, the glucose-sensitive swelling properties of the hollow needle body enable intelligent regulation of the insulin release process. In in vitro swelling and release tests, the microneedles exhibited stable swelling properties and excellent glucose-sensitive release characteristics.

[0055] The microneedle of the present invention comprises a hollow needle shell, a drug component, and a back patch. The hollow needle shell is prepared by molding a mixed gel of phenylboronic acid-modified ethylene glycol chitosan and dopamine-grafted oxidized dextran. The drug component is insulin powder, which is directly filled into the hollow needle shell to complete the drug loading step.

[0056] The back patch is prepared using an aqueous solution of hyaluronic acid as a substrate. The microneedles described have a glucose concentration-responsive drug release capability, enabling effective skin penetration and long-lasting drug release.

[0057] The intelligent glucose-responsive microneedle prepared by this invention allows for customization of the drug-loaded cavity size and improves drug loading efficiency. Furthermore, by adjusting the cross-linking degree and solid content of the mixed gel, the drug release rate and duration can be customized to meet specific therapeutic needs. The microneedles utilize a stable and controllable glucose concentration-responsive swelling mechanism to enhance the safety of microneedle therapy.

[0058] The beneficial effects of this invention are:

[0059] 1. The microneedle of the present invention has a cavity structure, which can increase the drug loading capacity. Furthermore, the drug loading capacity can be customized by adjusting the crosslinking density and solid content in the needle gel substrate.

[0060] 2. The microneedle of this invention exhibits sensitive and long-lasting glucose concentration response characteristics. Through the intelligent glucose response behavior of the needle, the insulin loaded within is released in a glucose-sensitive manner. Furthermore, the microneedle possesses good mechanical strength and skin penetration efficiency.

[0061] 3. The microneedle substrate of the present invention has good biocompatibility and avoids the side effects of dissolving the needle material on the human body through a swelling and release mechanism, thereby further improving the safety of treatment. Attached Figure Description

[0062] Figure 1 The following is an optical microscope image of the needle shell with a cavity structure according to the present invention. The cavity structures in Figures (a), (b), and (c) decrease in size sequentially.

[0063] Figure 2 The following are scanning electron microscope images of the needle shell with a cavity structure according to the present invention: Figure (a) is a microneedle array, Figure (b) is a top view of the microneedle, Figure (c) is a side view of the microneedle, and Figure (d) is a top view of a single microneedle.

[0064] Figure 3 This is a graph showing the in vitro glucose-sensitive swelling test results of the microneedles of the present invention;

[0065] Figure 4 The figures show the in vitro glucose-sensitive release test results of the microneedles of the present invention. Figure (a) shows the cumulative release under three glucose concentration environments, and Figure (b) shows the alternating release under gradient glucose concentration environments.

[0066] Figure 5 The figures show the biocompatibility test results of the microneedle substrate of the present invention. Figure (a) shows the hemolytic test and Figure (b) shows the cytotoxicity test.

[0067] Figure 6 The image shows the results of a pigskin puncture test using the microneedle tube of the present invention. Detailed Implementation

[0068] The present invention will now be described in more detail with reference to the accompanying drawings and embodiments. However, the present invention is not limited thereto. For those skilled in the art, several improvements and modifications can be made without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention. Contents not described in detail in this specification are prior art known to those skilled in the art.

[0069] Specific embodiments of the present invention are as follows:

[0070] Example 1:

[0071] 1) Dissolve 0.5694 g of 3-carboxyphenylboronic acid in 20 mL of dimethyl sulfoxide (DMSO) to prepare a DMSO solution of 3-carboxyphenylboronic acid. Dissolve 0.5965 g of ethylene glycol chitosan in 50 mL of deionized water to prepare an aqueous solution of ethylene glycol chitosan. Dissolve 0.2855 g of EDC and 0.1896 g of NHS in 10 mL of deionized water to prepare an aqueous catalyst solution. Slowly pour the aqueous catalyst solution into the DMSO solution of 3-carboxyphenylboronic acid, and then slowly add the aqueous solution of ethylene glycol chitosan. React at 25 °C for 6 h. Dialyze the reaction solution to deionized water for three days, and freeze-dry to obtain ethylene glycol chitosan grafted with phenylboronic acid.

[0072] 2) Dissolve 1.8963 g of dextran with a molecular weight of 30,000 in 20 mL of deionized water to prepare a dextran aqueous solution. Dissolve 0.9563 g of sodium periodate in 20 mL of deionized water to prepare a sodium periodate aqueous solution. Slowly pour the sodium periodate aqueous solution into the dextran aqueous solution and react at 25 °C for 5 h. Dialyze the reaction solution into deionized water for three days, and then freeze-dry to obtain oxidized dextran.

[0073] 3) Dissolve 0.9638 g of the prepared oxidized dextran in 10 mL of deionized water to prepare an oxidized dextran aqueous solution. Dissolve 1.2589 g of dopamine hydrochloride in 20 mL of deionized water to prepare a dopamine hydrochloride aqueous solution. Slowly pour the dopamine hydrochloride aqueous solution into the oxidized dextran aqueous solution, purge with nitrogen gas, and react at 25 °C for 10 h. Dialyze the reaction solution to deionized water for three days, and freeze-dry to obtain dopamine-grafted oxidized dextran.

[0074] 4) Dissolve the ethylene glycol chitosan grafted with phenylboronic acid obtained in step 1) in deionized water to prepare an aqueous solution of ethylene glycol chitosan grafted with phenylboronic acid with a concentration of 10 mg / mL. Dissolve the oxidized dextran grafted with dopamine obtained in step 3) separately in deionized water to prepare an aqueous solution of oxidized dextran grafted with dopamine with a concentration of 50 mg / mL. Mix 100 μL of the aqueous solution of ethylene glycol chitosan grafted with phenylboronic acid and 100 μL of the aqueous solution of oxidized dextran grafted with dopamine to prepare a cross-linked hydrogel. Hydrogels with different solid contents and crosslinking densities were prepared by mixing 75 μL of an aqueous solution of ethylene glycol chitosan grafted with phenylboronic acid and 125 μL of an aqueous solution of oxidized dextran grafted with dopamine, while keeping the total volume of the mixed solution constant at 200 μL; or by mixing 125 μL of an aqueous solution of ethylene glycol chitosan grafted with phenylboronic acid and 75 μL of an aqueous solution of oxidized dextran grafted with dopamine.

[0075] 5) The cross-linked hydrogel obtained in step 4) was injected into a microneedle mold and centrifuged at 4000 rpm for 10 min. Then, it was dried in a desiccator at 25°C and 10% humidity for 12 h. Afterward, depending on the cavity volume, 5, 10, and 15 IU of insulin powder were added, respectively, and 100 μL of a 300 mg / mL hyaluronic acid aqueous solution was added to the back. The mold was then dried again in a desiccator at 25°C and 10% humidity for 12 h to prepare needles with different drug loading capacities and different cavity structures.

[0076] 6) The prepared microneedles were observed using an optical microscope. For example... Figure 1 As shown, the microneedles have distinct cavity structures, indicated by dashed lines. In the experiment, by controlling the addition and mixing ratio of two modified polymer solutions in the gel, mixed gel systems with different concentrations of crosslinking sites were formed. By adjusting the crosslinking density and solid content, cavity structures of different sizes could be formed after drying. Figure 1 The cavity structures in (a)-(c) exhibit regular volume variations, and these cavity structures can directly load and store drug powders, significantly improving drug loading efficiency compared to microneedles loaded with solvent-based drugs. Furthermore, intelligent quantitative drug loading can be achieved through the design of the cavity size.

[0077] The microneedle structure was observed using a scanning electron microscope. In this embodiment, the size information of the needle body and the size information of the microneedle array are as follows: Figure 2 As shown, the prepared microneedle tubes have been confirmed to have a good microneedle array arrangement and a complete needle structure.

[0078] Example 2:

[0079] 1) Dissolve 0.7963 g of 3-carboxyphenylboronic acid in 25 mL of dimethyl sulfoxide (DMSO) to prepare a DMSO solution of 3-carboxyphenylboronic acid. Dissolve 0.6262 g of ethylene glycol chitosan in 50 mL of deionized water to prepare an aqueous solution of ethylene glycol chitosan. Dissolve 0.3696 g of EDC and 0.3578 g of NHS in 10 mL of deionized water to prepare an aqueous catalyst solution. Slowly pour the aqueous catalyst solution into the DMSO solution of 3-carboxyphenylboronic acid, and then slowly add the aqueous solution of ethylene glycol chitosan. React at 25 °C for 12 h. Dialyze the reaction solution to deionized water for three days, and freeze-dry to obtain ethylene glycol chitosan grafted with phenylboronic acid.

[0080] 2) Dissolve 1.6396 g of dextran with a molecular weight of 50,000 in 20 mL of deionized water to prepare a dextran aqueous solution. Dissolve 0.8822 g of sodium periodate in 15 mL of deionized water to prepare a sodium periodate aqueous solution. Slowly pour the sodium periodate aqueous solution into the dextran aqueous solution and react at 25 °C for 10 h. Dialyze the reaction solution into deionized water for three days, and then freeze-dry to obtain oxidized dextran.

[0081] 3) Dissolve 0.9999 g of the prepared oxidized dextran in 15 mL of deionized water to prepare an oxidized dextran aqueous solution. Dissolve 1.3693 g of dopamine hydrochloride in 25 mL of deionized water to prepare a dopamine hydrochloride aqueous solution. Slowly pour the dopamine hydrochloride aqueous solution into the oxidized dextran aqueous solution, purge with nitrogen gas, and react at 25 °C for 8 h. Dialyze the reaction solution to deionized water for three days, and freeze-dry to obtain dopamine-grafted oxidized dextran.

[0082] 4) Dissolve the ethylene glycol chitosan grafted with phenylboronic acid obtained in step 1) in deionized water to prepare an aqueous solution of ethylene glycol chitosan grafted with phenylboronic acid with a concentration of 50 mg / mL. Dissolve the oxidized dextran grafted with dopamine obtained in step 3) separately in deionized water to prepare an aqueous solution of oxidized dextran grafted with dopamine with a concentration of 100 mg / mL. Mix 100 μL of the aqueous solution of ethylene glycol chitosan grafted with phenylboronic acid and 200 μL of the aqueous solution of oxidized dextran grafted with dopamine to prepare a cross-linked hydrogel.

[0083] 5) The cross-linked hydrogel obtained in step 4) was injected into a microneedle mold and centrifuged at 3000 rpm for 20 min. Then, it was dried in a desiccator at 25°C and 10% humidity for 12 h. Afterward, 20 IU of insulin powder was added, and 100 μL of a 300 mg / mL hyaluronic acid aqueous solution was added to the back. It was then dried again in a desiccator at 25°C and 10% humidity for 24 h to prepare the drug-loaded needle shell with a hollow structure.

[0084] 6) Perform an in vitro glucose-sensitive swelling test on the prepared microneedles. For example... Figure 3 As shown, microneedles were placed in different glucose concentrations (0 mg / mL, 100 mg / mL, and 400 mg / mL), and their morphology was recorded at 6 h and 12 h. It can be seen that the microneedles exhibit more pronounced swelling behavior at higher glucose concentrations, and their structure remains intact throughout this process. These experiments confirm the swelling-release mechanism of the microneedles. Unlike dissolving microneedles, this microneedle avoids potential immune rejection and other side effects after the microneedle substrate dissolves, providing a safer way to deliver drugs and reducing the therapeutic risks in long-acting drug delivery.

[0085] Example 3:

[0086] 1) Dissolve 1.3569 g of 3-carboxyphenylboronic acid in 45 mL of dimethyl sulfoxide (DMSO) to prepare a DMSO solution of 3-carboxyphenylboronic acid. Dissolve 1.1715 g of ethylene glycol chitosan in 60 mL of deionized water to prepare an aqueous solution of ethylene glycol chitosan. Dissolve 0.9869 g of EDC and 0.8698 g of NHS in 20 mL of deionized water to prepare an aqueous catalyst solution. Slowly pour the aqueous catalyst solution into the DMSO solution of 3-carboxyphenylboronic acid, and then slowly add the aqueous solution of ethylene glycol chitosan. React at 25 °C for 8 h. Dialyze the reaction solution to deionized water for three days, and freeze-dry to obtain ethylene glycol chitosan grafted with phenylboronic acid.

[0087] 2) Dissolve 1.2145 g of 100,000 molecular weight dextran in 20 mL of deionized water to prepare a dextran aqueous solution. Dissolve 0.7896 g of sodium periodate in 15 mL of deionized water to prepare a sodium periodate aqueous solution. Slowly pour the sodium periodate aqueous solution into the dextran aqueous solution and react at 25 °C for 6 h. Dialyze the reaction solution to deionized water for three days, and then freeze-dry to obtain oxidized dextran.

[0088] 3) Dissolve 0.6939 g of the prepared oxidized dextran in 12 mL of deionized water to prepare an oxidized dextran aqueous solution. Dissolve 1.1515 g of dopamine hydrochloride in 18 mL of deionized water to prepare a dopamine hydrochloride aqueous solution. Slowly pour the dopamine hydrochloride aqueous solution into the oxidized dextran aqueous solution, purge with nitrogen gas, and react at 25 °C for 9 h. Dialyze the reaction solution to deionized water for three days, and freeze-dry to obtain dopamine-grafted oxidized dextran.

[0089] 4) Dissolve the ethylene glycol chitosan grafted with phenylboronic acid obtained in step 1) in deionized water to prepare an aqueous solution of ethylene glycol chitosan grafted with phenylboronic acid with a concentration of 90 mg / mL. Dissolve the oxidized dextran grafted with dopamine obtained in step 3) separately in deionized water to prepare an aqueous solution of oxidized dextran grafted with dopamine with a concentration of 90 mg / mL. Mix 100 μL of the aqueous solution of ethylene glycol chitosan grafted with phenylboronic acid and 300 μL of the aqueous solution of oxidized dextran grafted with dopamine to prepare a cross-linked hydrogel.

[0090] 5) The cross-linked hydrogel obtained in step 4) was injected into a microneedle mold and centrifuged at 4000 rpm for 25 mins. Then, it was dried in a desiccator at 25°C and 10% humidity for 24 h. Afterward, 15 IU of insulin powder was added, and 100 μL of a 300 mg / mL gelatin aqueous solution was added to the back. The mixture was then dried again in a desiccator at 25°C and 10% humidity for 12 h to prepare the drug-loaded needle shell with a hollow structure.

[0091] 6) Perform an in vitro glucose-sensitive release test on the prepared microneedles. For example... Figure 4 As shown, insulin-loaded microneedles were placed in different glucose environments (0 mg / mL, 100 mg / mL, and 400 mg / mL) to test drug release. Figure 4 As shown in (a), the difference in insulin release within the microneedle over a 16-hour release period was determined by the glucose concentration in the external environment, with the highest release rate at a glucose concentration of 400 mg / mL, accumulating to 16.1%. The release rate was relatively high in the first 4 hours; from 4 to 16 hours, the release rate decreased slowly, indicating that during glucose-sensitive release, the cross-linked structure within the gel continuously establishes new equilibrium systems and can maintain the release differences under different glucose concentrations. Therefore, it can be inferred that this microneedle can release drugs and exert therapeutic effects over a longer period. Figure 4 As shown in (b), the release test under varying glucose concentrations revealed a glucose concentration-dependent difference in release rate. The release rate at a glucose concentration of 400 mg / mL was significantly higher than that at other glucose concentrations, further highlighting the glucose sensitivity and release sensitivity of the microneedles under varying glucose concentrations. In conclusion, the microneedles demonstrated good glucose sensitivity and long-acting potential for insulin release control in in vitro glucose sensitivity tests.

[0092] 7) The prepared microneedle substrate was subjected to cytotoxicity and hemolytic activity tests. For example... Figure 5 As shown, Figure 5 (a) It was confirmed that the substrate of the microneedles did not have significant cytotoxicity and did not inhibit normal cell growth and reproduction. Figure 5 (b) It was confirmed that the substrate of the microneedle tube has good blood compatibility.

[0093] like Figure 6 As shown, the prepared microneedles exhibit excellent skin puncture performance, as demonstrated by comparison. Figure 6 (a) and Figure 6 (c) Clear puncture marks left by the microneedle on the pigskin can be observed. Each dark spot represents a tiny cavity left by the microneedle during the puncture process. Figure 6 (d) After cleaning with alcohol, the corresponding sites left by the microneedle on the skin can still be found after piercing the pig skin, which confirms that the microneedle has a high efficiency in skin puncture.

[0094] As can be seen from the above embodiments, the present invention provides a smart glucose-responsive microneedle, its preparation method, and its application. The smart glucose-responsive microneedle of the present invention can achieve a customizable cavity structure by adjusting the degree of crosslinking and solid content of the crosslinked hydrogel of the microneedle substrate, thereby enabling customized design of drug loading. This microneedle releases insulin via glucose-sensitive swelling, reducing the immune rejection effect caused by microneedle dissolution in the body. Furthermore, this microneedle regulates the glucose-sensitive response process through the synergistic effect of multiple crosslinking, achieving a more sustained release effect, thereby achieving safe, long-term, and intelligent blood glucose control.

Claims

1. A smart glucose-responsive microneedle, characterized in that, The microneedle consists of a needle shell with a cavity structure and a drug component. The drug component is encapsulated within the cavity structure of the needle shell. The needle shell with a cavity structure is made of a mixed gel composed of modified polymers. The drug component is a solid powder or a solution. The modified polymer is composed of modified ethylene glycol chitosan and modified oxidized dextran; The intelligent glucose-responsive microneedle was prepared according to the following method: 1) The compound containing phenylboronic acid groups, ethylene glycol chitosan, and the catalyst were dissolved in solvents to obtain their respective solutions. Then, the three solutions were mixed and reacted to prepare ethylene glycol chitosan grafted with phenylboronic acid. In step 1), the compound containing the phenylboronic acid group is specifically one or both of 3-carboxyphenylboronic acid and 4-carboxyphenylboronic acid; 2) Dextran and sodium periodate were dissolved separately in deionized water to obtain their respective solutions, and then the two solutions were mixed and reacted to prepare oxidized dextran; 3) Oxyglucan and dopamine hydrochloride were dissolved separately in deionized water to obtain their respective solutions, and then the two solutions were mixed and reacted to prepare dopamine-grafted oxyglucan. 4) Dissolve the ethylene glycol chitosan grafted with phenylboronic acid obtained in step 1) and the oxidized dextran grafted with dopamine obtained in step 3) in deionized water respectively, and then mix the two solutions to prepare a cross-linked hydrogel. 5) The cross-linked hydrogel obtained in step 4) is injected into the microneedle mold for centrifugation and drying. Then, the drug component is added to prepare a drug-loaded needle shell with a cavity structure, which is the smart glucose-responsive microneedle tube.

2. The intelligent glucose-responsive microneedle according to claim 1, characterized in that, The microneedle also includes a back patch, which is fixed to the surface of the needle shell and is made from a solution of natural polymer materials.

3. The method for preparing the intelligent glucose-responsive microneedle according to any one of claims 1-2, characterized in that the method... include: 1) The compound containing phenylboronic acid groups, ethylene glycol chitosan, and the catalyst were dissolved in solvents to obtain their respective solutions. Then, the three solutions were mixed and reacted to prepare ethylene glycol chitosan grafted with phenylboronic acid. In step 1), the compound containing the phenylboronic acid group is specifically one or both of 3-carboxyphenylboronic acid and 4-carboxyphenylboronic acid; 2) Dextran and sodium periodate were dissolved separately in deionized water to obtain their respective solutions, and then the two solutions were mixed and reacted to prepare oxidized dextran; 3) Oxyglucan and dopamine hydrochloride were dissolved separately in deionized water to obtain their respective solutions, and then the two solutions were mixed and reacted to prepare dopamine-grafted oxyglucan. 4) The ethylene glycol chitosan grafted with phenylboronic acid obtained in step 1) and the oxidized dextran grafted with dopamine obtained in step 3) were dissolved in deionized water, and then the two solutions were mixed to prepare a cross-linked hydrogel. 5) The cross-linked hydrogel obtained in step 4) is injected into the microneedle mold for centrifugation and drying. Then, the drug component is added to prepare a drug-loaded needle shell with a cavity structure, which is the smart glucose-responsive microneedle tube.

4. The method for preparing the intelligent glucose-responsive microneedle according to claim 3, characterized in that: In step 1), the amount of compound containing phenylboronic acid group added is 0.01-6 g, the amount of ethylene glycol chitosan added is 0.01-6 g, the amount of solvent used is 2-100 mL, the amount of catalyst used is 20%-80% of the mass of compound containing phenylboronic acid group added, and the amount of catalyst added is 0.002-4.8 g. In step 1), the catalyst specifically includes one or more of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS); the solvent is one or more of deionized water, methanol, isopropanol, anhydrous ethanol, dimethyl sulfoxide, and N,N-dimethylformamide.

5. The method for preparing the intelligent glucose-responsive microneedle according to claim 3, characterized in that: Step 2) specifically refers to: 2.1) Dissolve dextran of different molecular weights in deionized water to prepare mixed solution C; 2.2) Dissolve sodium periodate in deionized water to prepare mixed solution D; 2.3) Pour mixed solution D into mixed solution C and stir to react and obtain the second reaction solution; 2.4) The solution after the second reaction was subjected to dialysis and freeze-drying in sequence to prepare oxidized dextran; In step 2), the molecular weight of the dextran is 30,000 to 100,000, the amount of dextran added is 0.01-5 g, and the amount of sodium periodate added is 0.01-5 g.

6. The method for preparing the intelligent glucose-responsive microneedle according to claim 3, characterized in that: Step 3) specifically refers to: 3.1) Dissolve oxidized dextran in deionized water to prepare mixed solution E; 3.2) Dissolve dopamine hydrochloride in deionized water to prepare a mixed solution F; 3.3) Pour mixed solution F into mixed solution E and stir to react and obtain the solution after the third reaction; 3.4) The solution after the third reaction was subjected to dialysis and freeze-drying in sequence to prepare dopamine-grafted oxidized dextran; In step 3), the amount of oxidized dextran added is 0.01-5 g, and the amount of dopamine hydrochloride added is 0.01-5 g.

7. The method for preparing the intelligent glucose-responsive microneedle according to claim 3, characterized in that: In steps 1), 2), and 3), the reaction temperature is 5-25℃ and the reaction time is 1-48 hours. In step 4), the aqueous solution concentration of ethylene glycol chitosan grafted with phenylboronic acid is 5-500 mg / mL, the aqueous solution concentration of oxidized dextran grafted with dopamine is 5-500 mg / mL, and the volume ratio of the two solutions is 1:3 to 3:

1.

8. The use of the intelligent glucose-responsive microneedle according to any one of claims 1-2 or the intelligent glucose-responsive microneedle prepared by any one of claims 3-7 in the preparation of diabetes drugs.

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