Hydrogel microneedle patch for noninvasive blood glucose detection as well as preparation method and application of hydrogel microneedle patch

Abstract

The invention discloses a hydrogel microneedle patch for noninvasive blood glucose detection as well as a preparation method and application of the hydrogel microneedle patch. According to the invention, the microneedle patch is prepared by a turnover technology and is noninvasively applied to the skin surface, so that simple and rapid extraction of interstitial fluid in vivo and a new method for real-time, rapid and quantitative detection of blood glucose in vivo are realized. The hydrogel microneedle patch contains two hydrogel components: one hydrogel component is hydrogel which can be cured and formed by ultraviolet light, and the other hydrogel component is hydrogel which can be cured and formed by ultraviolet light; and the other hydrogel is functional hydrogel with pH responsiveness, and glucose oxidase is added, so that the hydrogel can sensitively react to in-vivo glucose. The double-response hydrogel is jointly mixed and prepared into a microneedle patch form, the microneedle patch is endowed with noninvasive / minimally invasive property when applied to the skin surface, the microneedle patch is very suitable for extraction of interstitial fluid in vivo, and then real-time, rapid and accurate detection of the blood glucose level in vivo is achieved.

Description

[0001] This application is a divisional application of the patent application with the application date of March 24, 2022, application number 202210298034.8, and invention title "A hydrogel microneedle patch for non-invasive blood glucose detection, its preparation method and application". Technical Field

[0002] The present invention belongs to the field of biomedical research, and particularly relates to a hydrogel microneedle patch for non-invasive blood glucose detection, its preparation method and application. Background Art

[0003] Diabetes is a global chronic disease that seriously threatens human health and life safety, and its typical feature is hyperglycemia. The World Health Organization reported that in 2017, there were approximately 425 million adult diabetes patients globally, and it is expected that the number of patients will continue to increase with the aging of the population and the change of lifestyle. If the blood glucose level is not well controlled, it will cause various complications in diabetic patients, such as amputation, blindness, cardiovascular and kidney diseases, etc., and in severe cases, even lead to death. Regular blood glucose monitoring for diabetic patients can better control blood glucose and prevent complications.

[0004] The blood glucose monitoring products on the market usually adopt the method of finger blood collection and use a source-based blood glucose test instrument to detect the blood glucose value of the collected fingertip blood. Repeated punctures of the finger will not only cause pain and reduced compliance in patients, but also lead to skin irritation and bacterial infection.

[0005] Researchers have conducted a large number of studies on non-invasive blood glucose monitoring. Among them, optical measurements, such as infrared spectroscopy, optical coherence tomography, and fluorescence, are easily interfered by confounding factors. Indirect measurements using metabolic heat, Raman spectroscopy, impedance, and polarization changes lack specificity for glucose. Body fluids, such as sweat, saliva, and tears, can also be used to measure the glucose level in the body. However, the glucose concentration in these fluids is only 1-10% of that in the blood, and is affected by environmental temperature changes, drugs, and components such as lactate in the body fluids. Therefore, the blood glucose correlation is weak and the measurement accuracy is uncertain.

[0006] Compared with the above methods, measuring glucose in interstitial fluid (ISF) in the body is more promising because interstitial fluid is a particularly rich source of soluble bioanalytes (including proteins, polypeptides, metabolites, and nucleic acids) and is closely related to blood. Currently, methods for extracting interstitial fluid include ultrasound, laser technology, and reverse iontophoresis, etc. Although reverse iontophoresis is the most common among these methods, its blood glucose correlation needs to be further improved, and currently it is rarely recognized by doctors. In addition, the use of high-density current and long preheating often cause skin irritation and pain to users.

[0007] Compared with interstitial fluid extraction, microneedles based on biorecognition elements can specifically capture biomarkers in interstitial fluid and then react, enabling simple and efficient biological detection. Summary of the Invention

[0008] Aiming at the above technical problems, the purpose of the present invention is to provide a hydrogel microneedle patch for non-invasive blood glucose detection, its preparation method and application. The present invention utilizes an intelligent hydrogel capable of quantitatively detecting glucose levels, and prepares hydrogel microneedles through microneedle technology to in-situ extract interstitial fluid and perform real-time, rapid, and efficient analysis and detection of glucose in interstitial fluid, which can be used for non-invasive blood glucose detection.

[0009] In the first aspect, the present invention provides a preparation method of a hydrogel microneedle patch for non-invasive blood glucose detection. The hydrogel microneedle patch is a square array structure formed by arranging sharp conical microneedle hydrogels on a substrate. The preparation method includes the following steps: (1) Under light-shielded conditions, mix a photosensitive hydrogel solution, a photoinitiator, glucose oxidase, and a pH-responsive functional hydrogel solution, pour it into a microneedle template, and preform by high-speed centrifugation; then cure and form a microneedle array under light irradiation; the sensitive hydrogel is a methacrylated gelatin hydrogel solution; the pH-responsive functional hydrogel solution is prepared from carboxymethyl cellulose and 2-hydroxyethyl acrylate under the combined action of potassium persulfate and polyethylene glycol diacrylate. (2) Under light-shielded conditions, coat the bottom surface of the microneedle array with a transparent photosensitive resin; then cure it with ultraviolet light to form the substrate of the microneedle array. (3) Dry and demold to form a hydrogel microneedle patch.

[0010] All designs of the present invention use biocompatible materials. This system contains two hydrogel components: one is the photosensitive hydrogel methacrylated gelatin (GelMA), which has the property of photocuring and forming, and can also be other photosensitive hydrogels; the other is the pH-responsive functional hydrogel, abbreviated as CMC-pHEA, which has the property of pH-responsive deformation, and can also be other types of pH-responsive hydrogels. In order to accelerate the pH responsiveness of the CMC-pHEA hydrogel, it is ultrasonically fragmented to form CMC-pHEA nanogels.

[0011] The present invention integrates glucose oxidase into the above pH-responsive hydrogel microneedles. When the microneedles come into contact with glucose, due to the action of glucose oxidase, glucose reacts to produce gluconic acid, causing the hydrogel microneedles to be in different acidic microenvironments (i.e., different pH values), thereby enabling the hydrogel microneedles to exhibit specific and responsive changes to different glucose concentrations.

[0012] Further, the microneedle patch contains at least one microneedle and can be in a single-row or array structure; the height of the conical microneedle is 100 - 800 μm; the distance between microneedles in the single-row or array is 100 - 800 μm. Preferably, the height of the conical microneedle is 600 μm, the diameter is 400 μm, and the distance from the tip of one needle to the tip of another is 600 μm; the microneedle array consists of 11 × 11 needles and has a size of 6.3 × 6.3 mm; the size of the square array structure is 1 × 1 cm. In practical applications, due to the extremely small size of the microneedles, their effect on tissues is very small and they do not reach blood vessels and peripheral nerves. Therefore, patients rarely or do not feel pain and do not bleed. Users can insert the microneedles into any part of the body, such as the arm, abdomen, etc. The microneedles extract interstitial fluid through surface tension and undergo a swelling reaction according to the blood glucose concentration.

[0013] Further, the photoinitiator is I2959 ultraviolet photoinitiator or LAP blue light photoinitiator, and the mass percentage of the photoinitiator is 0.05% - 0.1% of the weight of the hydrogel.

[0014] Further, the concentration of glucose oxidase in the hydrogel is 0.02 - 0.05 g / m1.

[0015] Further, the methacrylated gelatin hydrogel is prepared by dissolving methacrylated gelatin in water at a mass percentage of 8% - 12% to obtain a methacrylated gelatin hydrogel solution.

[0016] Further, the preparation method of the pH-responsive functional hydrogel solution is as follows: (a) Dissolve carboxymethyl cellulose in water at 50 - 100 °C with a stirring speed of 300 - 500 r / min: (b) In the presence of an inert gas, add potassium persulfate to the solution obtained in step (a) and mix and react: (c) Add 2-hydroxyethyl acrylate to the solution in step (b) and continue to react until the solution becomes milky white: (d) Add polyethylene glycol diacrylate to the solution in step (c) and continue to react until completion: (e) Dialyze the reaction product obtained in step (d) to remove unreacted reactants to obtain the pH-responsive hydrogel; The molar ratio of the carboxymethyl cellulose, 2-hydroxyethyl acrylate, initiator, and crosslinker is: 1:((5.48 - 8.62)×10 3 ) :(2.65 - 3.60) :(28.77 - 86.33).

[0017] Further, the photosensitive resin is clear v4 transparent photosensitive resin produced by Formlabs, USA.

[0018] Further, in the step (1), the light parameters are blue light, purple light or ultraviolet light, and the light irradiation time is 3 - 60 s; in the step (2), the ultraviolet curing time is 1 - 2 h. Preferably, the blue-violet light is 405 nm, and the light irradiation time is about 3 s; in the step (2), the ultraviolet curing time is about 2 h.

[0019] In the second aspect, the present invention provides a non-invasive hydrogel microneedle patch prepared by using the method described in the first aspect.

[0020] In the third aspect, the present invention provides the use of the non-invasive hydrogel microneedle patch described in the second aspect as a microneedle patch for non-invasive blood glucose detection.

[0021] Since the microneedles are non-invasive or minimally invasive, the hydrogel is prepared in the form of microneedles. By using the sharp inverted triangular shape of the microneedles, it is beneficial to pierce the skin and quickly extract interstitial fluid in the body. Further, the hydrogel microneedles produce specific and responsive changes to glucose in the interstitial fluid. After pulling out the microneedles, observe the changes in the height and swelling rate of the microneedles to detect the glucose level in the body in real time and quantitatively ( Figure 1 ).

[0022] The beneficial effects of the present invention are as follows: The microneedle array design of the non-invasive blood glucose detection hydrogel microneedle patch, combined with the glucose-responsive characteristics of the hydrogel, can be used for blood glucose detection and can achieve non-invasive or minimally invasive and visual rapid in-vivo blood glucose detection.

[0023] The present invention prepares a pH-responsive hydrogel material in the form of microneedles. The double-layer microneedle patch ensures the independent response of the microneedle part, and quantitative pH and blood glucose detection can be carried out through the change in the height of the microneedles. The microneedles detect blood glucose through the squeezed interstitial fluid, and the reaction is very rapid, only taking 5 s. It is non-invasive and painless, and will not cause infection problems, making it easier to improve the compliance of patients. The changes in the height of the microneedles corresponding to normal blood glucose and hyperglycemia are observable by the naked eye and can be quickly qualitatively determined.

[0024] The preparation method provided by the present invention has simple preparation steps and easy-to-achieve process conditions. Combined with a microneedle template, it is formed by photocuring to prepare the hydrogel microneedle patch described in the present invention. Description of the Drawings

[0025] Figure 1 It is a schematic diagram of a microneedle patch for non-invasive blood glucose detection and its working principle; Figure 2 It is the characterization of the acidic microenvironment generated at different glucose concentrations. (a) The mechanism of action of glucose reacting to produce an acidic microenvironment; (b) The acidic change of different concentrations of glucose solutions over time; Figure 3 Schematic diagram of the preparation process of intelligent hydrogel double-layer microneedles; Figure 4 Apparent morphology and microscopic structure diagram of the microneedles; Figure 5 Glucose responsiveness of the microneedles in skin-mimicking. (a) Pictures of the microneedle array after puncturing skin-mimicking (agarose gel) containing different concentrations of glucose; (b) Magnified picture of a single microneedle; (c) Heights of the microneedles at different glucose concentrations; (d) Swelling ratios of the microneedles at different glucose concentrations; Figure 6 Non-invasive effect of the microneedle patch on the skin of small animals. (a) Schematic diagram of the microneedle patch applied to the surface of a mouse's skin; (b) Photograph of the microneedle patch applied to the surface of a mouse's skin; (c) Picture of the pinholes left on the mouse's skin after removing the microneedles; (d) H&E stained picture of a section of the mouse's skin at the pinhole; (e) Pictures of the skin recovery effect at different times after removing the microneedles; Figure 7 Detection effect of the microneedle patch on the blood glucose of mice. (a) Blood glucose values in mice detected by a commercial blood glucose meter; (b) Corresponding pictures after the microneedles are applied to the skin of different mice; (c) Heights of the microneedles corresponding to different blood glucose concentrations in mice; (e) Swelling ratios of the microneedles corresponding to different blood glucose concentrations in mice. Specific implementation mode

[0026] The content of the present invention will be further described below in conjunction with specific embodiments, and the content of the present invention is not limited thereto at all.

[0027] Example 1 1. Preparation of pH-responsive hydrogel CMC-pHEA First, put 50 ml of distilled water and carboxymethyl cellulose (CMC) (5.56×10 -6 mol) into a 250 ml three-necked round-bottom flask, and stir in a water bath at a speed of 75 °C (50 - 100 °C, preferably 75 °C) and 400 rpm (300 - 500 rpm, preferably 400 rpm) until the CMC is fully dissolved. Then inject nitrogen into the pressure bottle containing the CMC solution for 20 minutes to fully reduce the oxygen content in the solution, and then add potassium persulfate (KPS, 1.85×10 -5 mol) as an initiator to the solution and mix for reaction for 20 minutes. Next, add 3.92×10 -2 mol of 2-hydroxyethyl acrylate (2-HEA). When the reaction mixture turns milky white, add 0.32×10 -3The reaction was continued for 3 hours with 1 mol of crosslinker polyethylene glycol diacrylate (PEGDA). After completion of the reaction, the mixture was cooled to room temperature. During the synthesis, the stirring speed was adjusted to induce homogeneous synthesis. The compound was dialyzed with 5 L of distilled water for more than 3 days to remove unreacted crosslinker and monomer to form a pH-responsive hydrogel CMC-pHEA. The hydrogel was then broken up using an ultrasonic disruptor.

[0028] 2. Preparation of Methacrylic Anhydride-Conjugated Gelatin Hydrogel (GelMA) Photoresponsive Hydrogel Dissolve the GelMA raw material in deionized water at a 10% by mass percentage (8%-12%, preferably 10%). Dissolve the LAP blue photoinitiator in the 10% GelMA solution at a 0.05%-0.1% by mass percentage. Operate in the dark to prevent the GelMA from cross-linking under natural light. Also, in the dark, ultrasonicate at 37°C (28-45°C, preferably 37°C) for 5 minutes to thoroughly mix. Then, soak in 37°C hot water for half an hour to fully dissolve. Irradiate the mixed solution under a 405m light source and cure instantly (approximately 1-2 seconds) to obtain a light-cured GelMA photosensitive hydrogel.

[0029] 3. Preparation of Dual-responsive Hydrogel System Leveraging the pH-responsiveness of CMC-pHEA nanogels and the photocuring properties of GelMA hydrogels, the two hydrogels were mixed in a 1:3 volume ratio. Glucose oxidase (GOx) was added and dissolved in the hydrogel solution to yield a 34 mg / mL enzyme solution. The mixture was then incubated in a 50°C oven until bubbles disappeared and the solution became clear. The mixture was then irradiated with 405nm UV light and photocured to produce a pH- and glucose-responsive hydrogel.

[0030] The prepared hydrogel contains CMC-pHEA nanogel components, so the hydrogel is responsive to pH. In an acidic environment, the hydrogel swells less; in a neutral environment, the hydrogel swells more.

[0031] Glucose oxidase can convert glucose into gluconic acid ( Figure 2 a), lowering the pH in the environment ( Figure 2 b). We confirmed the changes in pH values of different glucose solutions. The pH value decreased with the extension of incubation time, and the higher the glucose concentration, the faster the pH value of the solution decreased ( Figure 2 b).

[0032] Due to the different acidity microenvironments generated under different glucose concentrations, this hydrogel is also responsive to glucose, that is: at normal glucose concentrations, the hydrogel is neutral or weakly acidic around it, and the hydrogel has a large swelling; in high-concentration glucose, the acidity around the hydrogel is strong, and the swelling degree of the hydrogel is small.

[0033] Due to the dual pH and glucose responsiveness of this hydrogel, it can be used for the detection of glucose accordingly.

[0034] 4. Preparation of dual hydrogel microneedles As Figure 3 shown, the above-mentioned dual-responsive hydrogel solution was incubated at 50 °C, and then dropped onto the surface of the microneedle mold. It was centrifuged three times by a high-speed centrifuge (40 °C, 3800 rpm, 10 min) to allow the hydrogel to fill into the mold cavity. The excess hydrogel on the surface was scraped off with a knife, and it was cured with blue-violet light with a wavelength of 405 nm, the light intensity was 20%, and the irradiation time was about 3 s. Then, a certain amount of transparent photosensitive resin (Formlabs, Clear V4) was dropped onto the surface of the mold. After the surface of the resin became flat, it was irradiated with ultraviolet light again for curing, the light intensity was 20%, and the irradiation time was about 2 h. After drying and demolding, a microneedle array with a hard transparent resin as the base and a hydrogel with dual pH and glucose responsiveness at the needle tip was obtained.

[0035] As Figure 4 shown, the prepared microneedle patch has a complete shape, contains 11 x 11 microneedles, and each microneedle presents a sharp conical structure.

[0036] 5. Preparation of skin-like gels containing different glucose concentrations To simulate the application of microneedles on the skin, we first prepared a skin-like gel using agarose.

[0037] Take 0.5 g of agarose and dissolve it in 10 ml of water, repeat 9 times to obtain 9 groups of samples. Heat it to 70 °C with continuous stirring until the agarose is completely dissolved. Add 0 mg, 5.4 mg, 10.8 mg, 16.2 mg, 21.6 mg, 27 mg, 32.4 mg, 36 mg, 39.6 mg of D-glucose to the agarose solution respectively, mix well, and prepare agarose solutions with glucose concentrations of 0, 3, 6, 9, 12, 15, 18, 20, 22 mM. Pour the solution into a small cell culture dish, cool it to room temperature and cover it for 30 min to obtain skin-like agarose gels with different glucose concentrations, with a height of 3 mm, which are used for the following microneedle puncture experiments.

[0038] 6. Visual detection of glucose concentration in skin-like Use a contact angle tester and its built-in CCD camera to measure the height change of the microneedles.

[0039] Fix the microneedle patch on the contact angle sample platform, adjust the position of the contact angle needle so that its tip is close to the tip of the microneedle and is at the same horizontal plane as the microneedles in the front row of the microneedle array, and focus to make both tips in focus. Use the CCD camera built in the contact angle tester to record the diameter of the contact angle needle and the height of a single microneedle in the microneedle array ( Figure 5 a).

[0040] Remove the microneedle patch, and press the microneedle array into the skin-like gel with your finger, pull it out after holding for 3 s. Use the contact angle instrument to measure the height of the microneedle tip again ( Figure 5 a). Replace the microneedles and the gel, and repeat the experiment, record the height change of the microneedles after piercing the skin-like gel containing different glucose concentrations.

[0041] Results and analysis: When the microneedles pierce into the skin-like material, the microneedles react with the glucose in the skin-like gel and produce responses to different degrees. By testing the size change of the microneedles in different skin-like materials, the glucose concentration in the skin-like material is analyzed. If placed in the skin-like material with normal glucose concentration, the area around the microneedles is weakly acidic and the microneedles have a large degree of swelling; if placed in the skin-like material with high glucose concentration, the area around the microneedles is strongly acidic and the microneedles have a small degree of swelling.

[0042] The results confirm that: after the microneedles pierce the skin-like material containing 6 mM glucose, the swelling is larger; after the microneedles pierce the skin-like material containing 12 mM glucose, the swelling is smaller ( Figure 5 b). Therefore, the level of blood glucose can be qualitatively judged by observing the morphology of the microneedles.

[0043] The statistical results show that after the microneedles pierce the skin-like materials containing different concentrations of glucose, the size of the microneedles shows a gradient and linear change with the change of glucose concentration ( Figure 5 c-d). With the increase of the glucose solution concentration, the height and swelling ratio of the microneedles gradually decrease ( Figure 5 c-d). Based on the results in the skin-like gel, according to the swelling ratio of the microneedles, the glucose concentration in the unknown skin-like material can be inferred.

[0044] 7. Visual detection of blood glucose concentration in vivo Use C57 black mice, and prepare diabetic model mice by intraperitoneal injection of streptozotocin (STZ) in the mice. By regulating the injection times and injection doses of STZ, mice with different blood glucose concentrations in vivo (hypoglycemic, normoglycemic, and hyperglycemic mice in vivo) can be obtained.

[0045] Depilate the back area of the black mice, disinfect with an alcohol cotton swab, and press the microneedle patch into the skin of the mice with the thumb (Figure 6 a-b), after maintaining for 3 seconds, remove the patch. Use the CCD camera of the contact angle instrument to measure the height of the hydrogel microneedles.

[0046] At different time points after removing the microneedle patch, use the camera to photograph and record the skin of the mouse to observe the skin recovery situation.

[0047] In addition, after removing the microneedle patch, immediately fix the skin of the mouse in tissue fixative, and after paraffin embedding, sectioning, and H&E staining, use a microscope to observe the interaction between the microneedles and the skin.

[0048] Result analysis: For mice, the microneedles can penetrate the skin of the mice well and leave hollow-shaped small holes on the skin ( Figure 6 c-d). After removing the microneedles, as time goes by, the skin of the mouse can recover to its original morphology ( Figure 6 e), verifying the non-invasive nature of the microneedle's effect on the skin.

[0049] For the microneedles, when the microneedles penetrate the skin, the interstitial fluid under the skin oozes out and contacts the microneedles. Glucose in the interstitial fluid reacts with glucose oxidase in the microneedles to generate gluconic acid, and different acidity microenvironments further cause different swelling degrees of the hydrogel microneedles.

[0050] After puncturing the skin of normal blood glucose mice (8.3 mM), the height change of the microneedles is the largest and its swelling rate is the largest; after puncturing the skin of hyperglycemic mice (25.7 mM), the height change of the microneedles is the smallest ( Figure 7 a-b). We analyzed the height of the microneedles after puncturing the skin of different mice ( Figure 7 c) and the swelling rate (7d). The results show that in mice with low blood glucose concentration (8.3 mM), the change in the height of the microneedles is the largest, and the swelling rate is as high as 21.8%; as the blood glucose concentration in the mouse body increases, the height of the microneedles gradually decreases. When the blood glucose in the mouse body is very high (25.7 mM, simulating hyperglycemia in diabetes), the swelling rate of the microneedles is only 1.8%.

[0051] The experimental trends in the in-vivo experiments of mice are consistent with those in the skin-like gels. Similarly, we can also deduce the blood glucose concentration in an unknown mouse body based on the change in the height of the microneedles after puncturing the mouse skin.

[0052] As described above, it is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the technical scope disclosed by the present invention shall all be included within the protection scope of the invention.

Claims

1. A preparation method of a hydrogel microneedle patch for non-invasive blood glucose detection, characterized in that, the hydrogel microneedle patch is formed by arranging sharp conical microneedle hydrogels on a substrate, the preparation method includes the following steps: (1) Under light-shielded conditions, mix a photosensitive hydrogel solution, a photoinitiator, glucose oxidase and a pH-responsive functional hydrogel solution, pour it into a microneedle template, and pre-form by high-speed centrifugation; then cure and form a microneedle array under light; the photosensitive hydrogel is a methacrylic anhydride gelatin hydrogel solution; the pH-responsive functional hydrogel solution is prepared from carboxymethyl cellulose and 2-hydroxyethyl acrylate under the combined action of potassium persulfate and polyethylene glycol diacrylate; (2) Coat the bottom surface of the microneedle array with a transparent photosensitive resin and cure it with ultraviolet light to form the substrate of the microneedle array; (3) Dry and demold to form a hydrogel microneedle patch; the microneedle patch contains at least one microneedle and can be a single-row or array structure; the height of the conical microneedle is 100-800 μm; the spacing between the microneedles in a single row or array is 100-800 μm; The hydrogel microneedles produce specific and responsive changes to glucose, and observe the height changes of the microneedles to detect the glucose level in the body in real time and quantitatively.

2. The preparation method according to claim 1, characterized in that: The photoinitiator is I2959 ultraviolet photoinitiator or LAP blue light photoinitiator, and the mass percentage of the photoinitiator is 0.05%-0.1% of the weight of the hydrogel. The transparent photosensitive resin is clear v4 resin produced by formlab company in the United States.

3. The preparation method according to claim 1, characterized in that: The concentration of glucose oxidase in the hydrogel is 0.02-0.05 g / m1.

4. The preparation method according to claim 1, characterized in that, The methacrylic anhydride gelatin hydrogel is prepared by dissolving methacrylic anhydride gelatin in water at a mass percentage of 8%-12% to obtain a methacrylic anhydride gelatin hydrogel solution.

5. The preparation method according to claim 1, characterized in that, The preparation method of the pH-responsive functional hydrogel solution is as follows: (a) Dissolve carboxymethyl cellulose in water at 50-100 °C and a stirring speed of 300-500 r / min: (b) In the presence of an inert gas, add potassium persulfate to the solution obtained in step (a) and mix and react: (c) Add 2-hydroxyethyl acrylate to the solution in step (b) and continue to react until the solution becomes milky white: (d) Add polyethylene glycol diacrylate to the solution in step (c) and continue to react until the end: (e) Dialyze the reaction product obtained in step (d) to remove unreacted reactants to obtain the pH-responsive hydrogel; The molar ratio of the carboxymethyl cellulose, 2-hydroxyethyl acrylate, initiator and crosslinking agent is: 1:((5.48 - 8.62)×10 3 ):(2.65 - 3.60):(28.77 - 86.33).

6. The preparation method according to claim 1, characterized in that: The light irradiation parameters in step (1) are blue light, purple light or ultraviolet light, and the light irradiation time is 3-60 s; the ultraviolet curing time in step (2) is 1-2 h.

7. A non-invasive hydrogel microneedle patch, characterized in that: Prepared by the preparation method according to any one of claims 1-6.

8. Use of the hydrogel microneedle patch according to claim 7 as a microneedle patch for preparing non-invasive blood glucose detection.

9. A method for using the non-invasive hydrogel microneedle patch according to claim 7, characterized in that, Including the following steps: A1. Fix the microneedle patch on the contact angle sample platform, adjust the position of the contact angle needle so that its tip is close to the tip of the microneedle and is in the same horizontal plane as the microneedles in the front row of the microneedle array, and focus so that the two tips are in focus at the same time; A2. Record the diameter of the contact angle needle and the height of a single needle in the microneedle array at this time; A3. Remove the microneedle patch, press the microneedle array into the test object, pull it out after maintaining for a certain period of time, use a contact angle meter to measure the height of the microneedle tip again, and infer the glucose concentration in the test object based on the change in the height of the microneedle.

10. The usage method according to claim 9, wherein It further includes the following steps: By replacing the microneedles and the test object and repeating the experiment, record the height changes after the microneedles penetrate the test objects with different glucose concentrations, and plot a standard curve.

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