High-sensitivity glucose colorimetric detector and preparation method thereof

Abstract

The invention relates to a high-sensitivity glucose colorimetric detector and a preparation method thereof, belongs to the field of new material preparation, and particularly belongs to the field of sensing and detection new material preparation. The glucose colorimetric detector is composed of a base material and a structural color nano-film coated on the base material, wherein the structural color nano-film is formed by orderly and alternately stacking a plurality of organic nano-gel layers and inorganic nano-oxide layers. A large number of mass transfer channels are provided for glucose through the water absorption swelling effect of the strong hydrophilic nanogel, the response speed is increased, a large number of anions are grafted in the nanogel in a modification mode, the electrostatic repulsion effect in the gel is improved, and colorimetric detection of glucose is achieved. The glucose colorimetric detector disclosed by the invention has the advantages of high sensitivity and high detection speed, is good in reversibility and reproducibility, and has very strong application potential and practical popularization value in the aspects of self-monitoring and management of diabetes mellitus.

Description

Technical Field

[0001] The present invention relates to a highly sensitive glucose colorimetric detector and a preparation method thereof, belonging to the field of new material preparation, specifically belonging to the field of new material preparation for sensing and detection. Background Art

[0002] Due to unhealthy living habits, increasingly common sugar additives, and excessive dependence on sugar intake, the population of diabetics has become increasingly large. The characteristic of diabetes is the accumulation of glucose in the blood. When the glucose concentration in the blood is higher than 10 mmol / L, the kidney's reabsorption of glucose is insufficient, resulting in glycosuria. Currently, various glucose detectors have been reported, including fluorescence detectors, electrochemical detectors, gel detectors, colorimetric detectors, etc. Among them, glucose colorimetric detectors have attracted much attention due to their intuitive, convenient, strong warning, and no external power consumption characteristics. This type of detector material can modulate visible light. After interacting with a certain concentration of glucose, its molecular or nanostructure changes, resulting in a change in the reflected light wavelength, thereby producing a color change to monitor the change in glucose concentration. However, to meet the needs of practical applications, the sensitivity of current glucose colorimetric detection materials still needs to be improved. At the same time, materials that can achieve non-invasive glucose colorimetric detection in urine environment are still urgently needed to be developed. Summary of the Invention

[0003] The present invention provides a highly sensitive glucose detector and a preparation method thereof. The present invention provides a large number of mass transfer channels for glucose through the water absorption and swelling of the strongly hydrophilic organic nanogel layer, accelerating the response speed. And the organic nanogel layer of the present invention grafts a large number of anions by modification, increasing the electrostatic repulsion inside the gel, thereby enhancing the swelling ability of the organic nanogel layer film in the detector of the present invention, making the detector have higher response sensitivity. Especially under the condition of low-concentration glucose, the detector can produce an obvious color change recognition effect.

[0004] A highly sensitive glucose colorimetric detector, the glucose colorimetric detector is composed of a substrate and a structural color nanometer film coated on the substrate, and the structural color nanometer film is composed of several organic nanogel layers and inorganic nano-oxide layers stacked in an orderly manner. Among them,

[0005] The inorganic nano-oxide layer is composed of inorganic nano-oxides, and the inorganic nano-oxides are one of titanium dioxide, manganese oxide, zinc oxide, zirconium oxide, or indium sesquioxide;

[0006] The organic nanogel layer is composed of a copolymer modified by grafting, and the copolymer is formed by cross-linking a strongly hydrophilic polymer monomer and a polymer monomer containing a phenylboronic acid group. Among them,

[0007] The strong hydrophilic polymer monomer is one of acrylamide, acrylic acid, methacrylic acid, N-hydroxymethyl acrylamide, N-(2-hydroxyethyl) acrylamide or hydroxyethyl acrylate; the polymer monomer containing a phenylboronic acid group is one of 3-acrylamidophenylboronic acid, 4-vinylphenylboronic acid or 4-((2-acrylamidoethyl)carbamoyl)-3-fluorophenylboronic acid.

[0008] Furthermore, the structural color nano-film is composed of at least one organic nano-gel layer and one inorganic nano-oxide layer.

[0009] Furthermore, the first layer on the side in contact with the substrate in the glucose colorimetric detector can be the organic nano-gel layer of the structural color nano-film or the inorganic nano-oxide layer.

[0010] More preferably, the first layer on the side in contact with the substrate in the glucose colorimetric detector is the organic nano-gel layer of the structural color nano-film.

[0011] Even further, one organic nano-gel layer and one inorganic nano-oxide layer form 1 stack.

[0012] The number of stacks of the present invention can be 1 or more. As the number of stacks increases, the reflectivity of the structural color nano-film increases and the color becomes more vivid. The number of stacks can theoretically be infinite. However, considering the influence of the number of stacks on the detection effect, too many stacks will reduce the sensitivity of the structural color film.

[0013] Preferably, the number of stacks of the structural color nano-film of the glucose colorimetric detector is 1 to 4 stacks.

[0014] Furthermore, when the structural color nano-film of the glucose colorimetric detector involves multiple stacks, each organic nano-gel layer can be grafted with a modification reagent.

[0015] In the above technical solution, the thickness of the structural color nano-film of the glucose colorimetric detector in air is 200 - 600 nm, and the thickness in aqueous solution is 300 - 1500 nm.

[0016] Furthermore, the thickness of the organic nano-gel layer of the structural color nano-film in air is 30 - 150 nm, and the thickness in aqueous solution is 80 - 400 nm.

[0017] Furthermore, the thickness of the inorganic nano-oxide layer of the structural color nano-film in both air and water is 30 - 150 nm.

[0018] In the above technical solution, the grafting modification method is to soak the structural color nano-film together with the substrate in a modification reagent solution and react at 25 °C for 5 - 10 min.

[0019] Further, the modifying reagent used for graft modification is one of alizarin red S, sodium 6,7-dihydroxynaphthalene-2-sulfonate, 3,4-dihydroxyphenylacetic acid, 3,4-dihydroxybenzoic acid or sodium catechol-3,5-disulfonate.

[0020] Further, the modifying reagent is a water-soluble small molecule having both cis-dihydroxy groups and acid groups.

[0021] Furthermore, the cis-dihydroxy groups in the modifying reagent covalently bond with the boronic acid groups in the copolymer to form borate ions, and then the modifying reagent is grafted onto the copolymer chain segments in the organic nanogel layer. At the same time, the acid groups in the modifying reagent are also introduced onto the copolymer chain segments.

[0022] In the modification process of the present invention, the uncharged boronic acid groups in the organic nanogel layer are promoted to be converted into borate ions, and acid groups are introduced. A large number of anions are grafted inside the organic nanogel layer, increasing the electrostatic repulsion inside it, thereby enhancing its swelling ability and making the glucose detector obtained by the present invention have higher response sensitivity.

[0023] In the above technical solution, a cross-linking agent is required when the strongly hydrophilic polymer monomer and the polymer monomer containing phenylboronic acid groups in the organic nanogel layer of the structural color nanometer thin film are cross-linked.

[0024] Further, the cross-linking agent is one of N,N'-methylenebisacrylamide, N,N'-vinylenebisacrylamide, ethylene glycol dimethacrylate or polyethylene glycol diacrylate.

[0025] In the above technical solution, the substrate of the glucose colorimetric detector is one of a silicon wafer, a glass sheet, polyester, polypropylene, polycarbonate, polyimide, polytetrafluoroethylene or polydimethylsiloxane.

[0026] Another object of the present invention is to provide a preparation method of the above glucose colorimetric detector.

[0027] A preparation method of a glucose colorimetric detector includes the following steps:

[0028] ① Using the reverse microemulsion method to prepare a nanogel emulsion containing a copolymer, and then through demulsification, dialysis and dispersion to obtain an organic nanogel dispersion containing the copolymer;

[0029] ② Weighing inorganic nano-oxides and dispersing them in water or an ethanol aqueous solution to prepare an inorganic oxide nanoparticle dispersion;

[0030] ③ Spin-coat or spray the organic nanogel dispersion containing the copolymer obtained in step ① on the substrate, and heat and dry it to obtain an organic nanogel layer; then spin-coat or spray the inorganic oxide nanoparticle dispersion obtained in step ② on the above-mentioned organic nanogel layer, and heat and dry it to obtain a structural color nanometer film coated on the substrate;

[0031] ④ Immerse the structural color nanometer film obtained in step ③ together with the substrate into the modified reagent solution and react to obtain a highly sensitive and rapid glucose colorimetric detector.

[0032] Further, the nanogel dispersion containing the copolymer and the inorganic oxide nanoparticles can be continuously spin-coated or sprayed alternately in sequence on the structural color nanometer film obtained in step ③, and the above steps are repeated to obtain an organic-inorganic composite structural color nanometer film with a multi-layer heterogeneous structure coated on the substrate.

[0033] Preferably, the number of repeated operations of continuously spin-coating or spraying the nanogel dispersion containing the copolymer and the inorganic oxide nanoparticle dispersion alternately in sequence is 0 to 4 times.

[0034] In the method of the present invention, in step ①, the mass fraction of the organic nanogel dispersion containing the copolymer is 1% to 4%.

[0035] Further, the average particle size of the copolymer in toluene is 60 to 120 nm, and the average particle size in an aqueous solution is 600 to 1500 nm.

[0036] In the method of the present invention, in step ②, the mass fraction of the inorganic oxide nanoparticle dispersion is 1% to 4%.

[0037] Further, the particle size of the inorganic oxide nanoparticles in water is 20 to 50 nm.

[0038] In the method of the present invention, in step ②, the volume ratio of ethanol to water in the ethanol aqueous solution is 1:1.

[0039] In the method of the present invention, the concentration of the modified reagent is 0.001 to 1 mM.

[0040] Preferably, the concentration of the modified reagent is 0.01 to 0.1 mM.

[0041] Further, the reagent required to dissolve the modified reagent is a phosphate buffer solution with a pH of 7.4.

[0042] In the method of the present invention, the inverse microemulsion method includes the following experimental steps: Add sodium bis(2-ethylhexyl) sulfosuccinate, a surfactant, to toluene, continuously stir and purge with nitrogen until the temperature reaches 75 °C to form micelles. Add an azobisisobutyronitrile toluene solution as an initiator, continue stirring for 2 - 5 min, and then dropwise add an aqueous mixed solution composed of a strongly hydrophilic polymer monomer, a phenylboronic acid-containing monomer, and a crosslinking agent to form a microemulsion. Keep it warm for 1 h, and after cooling, obtain a nano-gel emulsion containing a copolymer.

[0043] Further, the dropping method of the aqueous mixed solution composed of a strongly hydrophilic polymer monomer, a phenylboronic acid-containing monomer, and a crosslinking agent is to dropwise add it by using a quantitative injection pump at a speed of 0.1 mL·min -1 。

[0044] Further, the volume ratio of the sodium bis(2-ethylhexyl) sulfosuccinate toluene solution, the azobisisobutyronitrile toluene solution, and the aqueous mixed solution is 50:1 - 5:3 - 8.

[0045] Furthermore, the mass ratio of sodium bis(2-ethylhexyl) sulfosuccinate to toluene in the sodium bis(2-ethylhexyl) sulfosuccinate toluene solution is 1:15 - 25.

[0046] Furthermore, the mass ratio of deionized water to the strongly hydrophilic monomer, the boric acid-containing polymer monomer, and the crosslinking agent in the aqueous mixed solution is 1:0.5 - 1:0.1 - 0.15:0.01 - 0.1.

[0047] Preferably, the mass ratio of deionized water to the strongly hydrophilic monomer, the boric acid-containing polymer monomer, and the crosslinking agent in the aqueous mixed solution is 1:0.9 - 1:0.12 - 0.15:0.02 - 0.08.

[0048] Furthermore, the concentration of the azobisisobutyronitrile toluene solution is 0.01 - 0.05 mol / L.

[0049] In the method of the present invention, in step ③, the operation method for coating the organic nano-gel dispersion and the inorganic oxide nano-particle dispersion is preferably spin coating.

[0050] Further, the conditions for spin coating are to spin coat at a speed of 3000 - 5000 rpm for 30 - 50 s.

[0051] In the method of the present invention, in step ③, the conditions for heating and drying are to dry at 100 - 200 °C for 3 - 15 min.

[0052] In the method of the present invention, in step ④, the reaction conditions are to react at 25 °C for 5 - 10 min.

[0053] The organic nanogel layer of the present invention has strong hydrophilic properties and can swell significantly in water.

[0054] The structural color nano-film of the present invention is dark purple in air and turns bright cyan when immersed in water. At this time, a photonic bandgap appears. After grafting modification, a highly sensitive photonic crystal detector is obtained, which shows bright yellow-green at this time. When it is immersed in phosphate buffer solutions with different concentrations of glucose at pH = 7.4 respectively, the color of the detector gradually changes towards the long-wavelength direction.

[0055] Advantages of the present invention: By grafting and modifying the structural color nano-film containing phenylboronic acid groups inside with small molecules containing acid root ions and cis-dihydroxy groups, the present invention provides a highly sensitive glucose colorimetric detector and its preparation method. The sensitivity and detection range of the glucose colorimetric detector obtained in the present invention can be adjusted by changing the types and concentrations of the grafted small molecules, and it has the advantages of high sensitivity and fast detection speed. At the same time, it has good reversibility and reproducibility and has good application performance in the detection of human blood glucose and urine glucose. Description of the Drawings

[0056] Figure 1 It is the reflection spectrum of the glucose detector obtained in Example 1 in glucose solutions with different concentrations.

[0057] Figure 2 It is the digital photo of the glucose detector obtained in Example 1 in glucose solutions with different concentrations.

[0058] Figure 3 It is the graph of the change in reflection wavelength of the glucose detector obtained in Example 1 when immersed in a 7 mM glucose solution.

[0059] Figure 4 It is the reflection spectrum of the glucose detector obtained in Example 2 in glucose solutions with different concentrations.

[0060] Figure 5 It is the graph of the change in the position of the reflection peak of the glucose detectors obtained in Examples 6 - 10 when immersed in glucose solutions with different concentrations. Detailed Embodiments

[0061] The following non-limiting examples can enable those of ordinary skill in the art to understand the present invention more comprehensively, but do not limit the present invention in any way.

[0062] In the following examples, the test methods are all conventional methods unless otherwise specified; the reagents and materials can be obtained from commercial channels unless otherwise specified.

[0063] Example 1

[0064] A preparation method of a highly sensitive glucose colorimetric detector, comprising the following steps:

[0065] ① Preparation of a nano-gel dispersion containing a copolymer:

[0066] Use an ultrasonic cleaner to completely dissolve 4.25 g of acrylamide, 0.75 g of 3-acrylamidophenylboronic acid, and 0.20 g of N,N′-methylenebisacrylamide mixed in 2.50 g of deionized water to obtain a mixed aqueous solution; then, pour 2.5 g of the surfactant sodium bis(2-ethylhexyl) sulfosuccinate and 44.0 g of toluene into a 100.0 mL three-necked flask equipped with a nitrogen inlet, a feed inlet, and a reflux condenser. The solution is continuously stirred and purged with nitrogen until heated to 75 °C; at this time, pour the initiator solution prepared by dissolving 12.5 mg of azobisisobutyronitrile in 2 mL of toluene into the flask, continue stirring for 3 min, and then inject the above mixed solution with a metering syringe pump (0.1 mL·min -1 ) for 50 min; keep warm for 1 hour, then cool the mixture for 10 min, add 100 mL of ethanol to demulsify, centrifuge, dry the solid, put it into a dialysis bag, and perform dialysis purification in deionized water to separate unreacted monomers and sodium bis(2-ethylhexyl) sulfosuccinate. Finally, a copolymer nano-gel dispersion is obtained, wherein the average particle size of the copolymer in toluene is 70 nm, and the average particle size in aqueous solution is 800 nm;

[0067] ② Preparation of an inorganic oxide nanoparticle dispersion:

[0068] Weigh 1 g of titanium dioxide and dissolve it in 10 mL of an ethanol aqueous solution (the volume ratio of water to ethanol in the ethanol aqueous solution is 1:1) to obtain a titanium dioxide nanoparticle dispersion, wherein the particle size of the titanium dioxide nanoparticles is 25 nm;

[0069] ③ Preparation of a structural color nano-film coated on a substrate:

[0070] Take the nano-gel aqueous dispersion containing the copolymer obtained in step ① and dilute it with water to 1.72 wt%, and coat it on the surface of a silicon wafer by spin coating technology. During the spin coating process, the rotation speed is 4000 rpm and the spin coating time is 40 s. Then, heat the coated silicon wafer at 180 °C for 10 min and cool it down to obtain an organic nano-gel layer coated on the surface of the silicon wafer; take the titanium dioxide nanoparticle dispersion obtained in step ② and dilute it with water to 3.0 wt%, and then coat it on the surface of the above organic nano-gel layer film. The spin coating conditions are the same as those of the organic gel layer, and heat it at 180 °C for 3 min; repeat the above steps three times to prepare a structural color nano-film with a total thickness of about 300 nm, wherein the thickness of the organic nano-gel layer is 60 nm and the thickness of the titanium dioxide layer is 40 nm;

[0071] ④ Preparation of a highly sensitive glucose colorimetric detector:

[0072] Under the condition of 25 °C, immerse the above-prepared structural color nanofilms together with the substrate in a 0.025 mM alizarin red S solution (pH = 7.4) and keep for 10 min for graft modification to obtain a highly sensitive glucose colorimetric detector.

[0073] Put the highly sensitive glucose colorimetric detector obtained in Example 1 into phosphate buffer solutions containing different concentrations of glucose. The reflection spectra and digital photos are shown in Figure 1 and Figure 2 respectively. It can be seen that when the glucose concentration gradually increases from 0 mM to 10 mM, the position of the maximum reflection peak of the glucose colorimetric detector gradually redshifts from 571 nm to 666 nm, and the color gradually changes from the initial yellow to orange-red. The reflection peak displacement for 10 mM glucose is as high as 95 nm. Figure 3 Figure showing the change in the reflection wavelength of the glucose detector obtained in Example 1 when immersed in a 7 mM glucose solution. It can be seen that when the glucose detector is immersed in a 7 mM glucose buffer solution, the reflection peak rapidly redshifts, and the detection of glucose is completed within 60 s, showing a fast detection speed.

[0074] Examples 2 - 5

[0075] The method is the same as that in Example 1, but the solutions for immersing the structural color nanofilms are changed to sodium 6,7-dihydroxynaphthalene-2-sulfonate, 3,4-dihydroxyphenylacetic acid, 3,4-dihydroxybenzoic acid, and sodium catechol-3,5-disulfonate respectively.

[0076] When the modification reagent changes, the sensitivity of the prepared glucose colorimetric detector changes, and different structural color changes occur for 10 mM glucose. The reflection spectra of the glucose colorimetric detector modified with sodium 6,7-dihydroxynaphthalene-2-sulfonate in glucose solutions with different concentrations are shown in Figure 4 respectively. It can be seen that when the glucose concentration gradually increases from 0 mM to 10 mM, the position of the maximum reflection peak of the glucose colorimetric detector gradually redshifts from 584 nm to 693 nm. The reflection peak displacement for 10 mM glucose is as high as 109 nm, showing higher sensitivity.

[0077] Example 6

[0078] A preparation method of a highly sensitive glucose colorimetric detector, comprising the following steps:

[0079] ① Preparation of a nanogel dispersion containing a copolymer:

[0080] Dissolve 4.25 g of acrylamide, 0.75 g of 3-acrylamidophenylboronic acid, and 0.20 g of N,N'-methylenebisacrylamide in 2.50 g of deionized water using an ultrasonic cleaner to obtain a mixed aqueous solution. Then, pour 2.5 g of the surfactant sodium bis(2-ethylhexyl) sulfosuccinate and 44.0 g of toluene into a 100.0 mL three-necked flask equipped with a nitrogen inlet, a feed inlet, and a reflux condenser. The solution is continuously stirred and purged with nitrogen until it is heated to 75 °C. At this time, pour the initiator solution prepared by dissolving 12.5 mg of azobisisobutyronitrile in 2 mL of toluene into the flask, continue stirring for 3 min, and then inject the above mixed solution for 50 min using a metering injection pump (0.1 mL·min -1 ). Keep the temperature for 1 hour, then cool the mixture for 10 min, add 100 mL of ethanol to demulsify, centrifuge, dry the solid, put it into a dialysis bag, and perform dialysis purification in deionized water to separate unreacted monomers and sodium bis(2-ethylhexyl) sulfosuccinate. Finally, obtain a copolymer nanogel dispersion. Among them, the average particle size of the copolymer in toluene is 70 nm, and the average particle size in aqueous solution is 800 nm;

[0081] ② Preparation of inorganic oxide nanoparticle dispersion:

[0082] Weigh 1 g of titanium dioxide and dissolve it in 10 mL of an ethanol aqueous solution (the volume ratio of water to ethanol in the ethanol aqueous solution is 1:1) to obtain a titanium dioxide nanoparticle dispersion. Among them, the particle size of the titanium dioxide nanoparticles is 25 nm;

[0083] ③ Preparation of a structural color nanometer film coated on a substrate:

[0084] Dilute the nanogel aqueous dispersion containing the copolymer obtained in step ① with water to 1.54 wt%, and coat it on the surface of a silicon wafer by spin coating technology at a rotation speed of 5000 rpm for 40 s. Heat the coated silicon wafer at 180 °C for 10 min and then cool it down to obtain an organic nanogel layer coated on the surface of the silicon wafer. Dilute the titanium dioxide nanoparticle dispersion obtained in step ② with water to 3.0 wt%, and then coat it on the surface of the above organic nanogel layer film. The spin coating conditions are the same as those of the organic gel layer, and heat it at 180 °C for 3 min. Repeat the above steps three times to prepare a structural color nanometer film with a total thickness of about 270 nm. Among them, the thickness of the organic nanogel layer is 50 nm, and the thickness of the titanium dioxide layer is 40 nm;

[0085] ④ Preparation of a high-sensitivity glucose colorimetric detector:

[0086] At 25 °C, the obtained structural color nano-film together with the substrate was immersed in a 0.025 mM alizarin red S solution (pH = 7.4) for 10 min for graft modification, and a high-sensitivity glucose colorimetric detector was obtained.

[0087] Examples 7-10

[0088] The method was the same as that in Example 6, and the concentrations of alizarin red in the solution were changed to 0.01 mM, 0.05 mM, 0.075 mM, and 0.1 mM, respectively.

[0089] The reflection spectra of the glucose colorimetric detectors prepared with different concentrations of the modification reagent in different concentrations of glucose solutions are shown in Figure 5 , and it can be seen that: as the concentration of the modification reagent increases, the detection range of the glucose colorimetric detector gradually decreases, from 0-10 mM to 0-3 mM, but its response ability to low-concentration glucose of 0-1 mM increases.

[0090] Example 11

[0091] A preparation method of a high-sensitivity glucose colorimetric detector includes the following steps:

[0092] ① Preparation of a nano-gel dispersion containing a copolymer:

[0093] Using an ultrasonic cleaner, 4.25 g of acrylamide, 0.75 g of 3-acrylamidophenylboronic acid, and 0.20 g of N,N'-methylenebisacrylamide mixed in 2.50 g of deionized water were completely dissolved to obtain a mixed aqueous solution; then, 2.5 g of the surfactant sodium bis(2-ethylhexyl) sulfosuccinate and 44.0 g of toluene were poured into a 100.0 mL three-necked flask equipped with a nitrogen inlet, a feed inlet, and a reflux condenser. The solution was continuously stirred and purged with nitrogen until heated to 75 °C; at this time, the initiator solution prepared by dissolving 12.5 mg of azobisisobutyronitrile in 2 mL of toluene was poured into the flask, and stirring was continued for 3 min. Then, the above mixed solution was injected with a metering syringe pump (0.1 mL·min -1 ) for 50 min; the temperature was maintained for 1 hour, and then the mixture was cooled for 10 min. 100 mL of ethanol was added for demulsification, and centrifugation was carried out. The solid was dried and then placed in a dialysis bag and dialyzed and purified in deionized water to separate unreacted monomers and sodium bis(2-ethylhexyl) sulfosuccinate. Finally, a copolymer nano-gel aqueous dispersion was obtained, where the average particle size of the copolymer in toluene was 70 nm, and the average particle size in the aqueous solution was 800 nm;

[0094] ② Preparation of an inorganic oxide nanoparticle dispersion:

[0095] Weigh 1 g of titanium dioxide and dissolve it in 10 mL of an ethanol aqueous solution (the volume ratio of water to ethanol in the ethanol aqueous solution is 1:1) to obtain a dispersion of titanium dioxide nanoparticles. Among them, the particle size of the titanium dioxide nanoparticles is 25 nm;

[0096] ③ Preparation of the structural color nano-film coated on the substrate:

[0097] Dilute the nano-gel aqueous dispersion containing the copolymer obtained in step ① with water to 1.38 wt%, and coat it on the surface of the silicon wafer by spin coating technology at a rotation speed of 5000 rpm for 40 s. Heat the coated silicon wafer at 180 °C for 10 min and then cool it down to obtain an organic nano-gel layer coated on the surface of the silicon wafer; Dilute the dispersion of titanium dioxide nanoparticles obtained in step ② with water to 3.0 wt%, and then coat it on the surface of the silicon wafer coated with the organic nano-gel layer film. The spin coating conditions are the same as those of the organic gel layer, and heat it at 180 °C for 3 min; Repeat the above steps three times to prepare a structural color nano-film with a total thickness of about 300 nm. Among them, the thickness of the organic nano-gel layer is 40 nm, and the thickness of the titanium dioxide layer is 40 nm;

[0098] ④ Preparation of a highly sensitive glucose colorimetric detector:

[0099] Under the condition of 25 °C, immerse the obtained structural color nano-film together with the substrate in a 0.025 mM alizarin red S solution (pH = 7.4) for 10 min for graft modification to obtain a highly sensitive glucose colorimetric detector.

[0100] Examples 12 - 14

[0101] The method is the same as that in Example 11, and the concentrations of the titanium dioxide nanoparticle dispersions are changed to 2 wt%, 3 wt%, and 4 wt% respectively.

[0102] Example 15

[0103] A preparation method of a highly sensitive glucose colorimetric detector, comprising the following steps:

[0104] ① Preparation of a nano-gel dispersion containing a copolymer:

[0105] Dissolve 4.25 g of acrylamide, 0.75 g of 3-acrylamidophenylboronic acid, and 0.20 g of N,N'-methylenebisacrylamide in 2.50 g of deionized water using an ultrasonic cleaner to obtain a mixed aqueous solution; then, pour 2.5 g of the surfactant sodium bis(2-ethylhexyl) sulfosuccinate and 44.0 g of toluene into a 100.0 mL three-necked flask equipped with a nitrogen inlet, a feed inlet, and a reflux condenser. The solution is continuously stirred and purged with nitrogen until heated to 75 °C; at this time, pour the initiator solution prepared by dissolving 12.5 mg of azobisisobutyronitrile in 2 mL of toluene into the flask, continue stirring for 3 min, and then inject the above mixed solution with a metering syringe pump (0.1 mL·min -1 ) for 50 min; keep warm for 1 h, then cool the mixture for 10 min, add 100 mL of ethanol to demulsify, centrifuge, dry the solid, put it into a dialysis bag, and perform dialysis purification in deionized water to separate unreacted monomers and sodium bis(2-ethylhexyl) sulfosuccinate. Finally, obtain an aqueous dispersion of copolymer nanogels. Among them, the average particle size of the copolymer in toluene is 70 nm, and the average particle size in aqueous solution is 800 nm;

[0106] ② Preparation of inorganic oxide nanoparticle dispersion:

[0107] Weigh 1 g of zinc oxide and dissolve it in 10 mL of water to obtain a zinc oxide nanoparticle dispersion. Among them, the particle size of the zinc oxide nanoparticles is 30 nm;

[0108] ③ Preparation of a structural color nanometer film coated on a substrate:

[0109] Dilute the aqueous dispersion of copolymer nanogels containing the copolymer obtained in step ① with water to 1.54 wt%, and coat it on the surface of a silicon wafer by spin coating technology at a rotation speed of 5000 rpm for 40 s. Heat the coated silicon wafer at 180 °C for 10 min, and then cool it down to obtain an organic nanogel layer coated on the surface of the silicon wafer; dilute the zinc oxide nanoparticle dispersion obtained in step ② with water to 3.0 wt%, and then coat it on the surface of the organic nanogel layer film at 180 °C for 3 min; repeat the above steps three times to prepare a structural color nanometer film with a total thickness of about 270 nm. Among them, the thickness of the organic nanogel layer is 50 nm, and the thickness of the zinc oxide layer is 40 nm;

[0110] ④ Preparation of a high-sensitivity glucose colorimetric detector:

[0111] At 25 °C, immerse the above-obtained structural color nanometer film together with the substrate in a 0.025 mM alizarin red S solution (pH = 7.4) for 10 min for graft modification to obtain a high-sensitivity glucose colorimetric detector.

[0112] Examples 16 to 19

[0113] The method was the same as that of Example 15, and the masses of N,N'-methylenebisacrylamide were 0 g, 0.1 g, 0.3 g, and 0.4 g, respectively.

Claims

1. A high-sensitivity glucose colorimetric detector, characterized in that: The glucose colorimetric detector is composed of a substrate and a structural color nanofilm coated on the substrate, wherein the structural color nanofilm is composed of a plurality of organic nanogel layers and inorganic nanooxide layers stacked alternately in an orderly manner, wherein: The inorganic nano-oxide layer is composed of inorganic nano-oxide, and the inorganic nano-oxide is one of titanium dioxide, manganese oxide, zinc oxide, zirconium oxide or indium trioxide; The organic nanogel layer is composed of a graft-modified copolymer, wherein the copolymer is formed by cross-linking a strongly hydrophilic polymer monomer and a polymer monomer containing a phenylboronic acid group, wherein: The strongly hydrophilic polymerizable monomer is one of acrylamide, acrylic acid, methacrylic acid, N-hydroxymethyl acrylamide, N-(2-hydroxyethyl) acrylamide or hydroxyethyl acrylate; the polymerizable monomer containing a phenylboronic acid group is one of 3-acrylamidophenylboric acid, 4-vinylphenylboric acid or 4-((2-acrylamidoethyl)carbamoyl)-3-fluorophenylboric acid.

2. The glucose colorimetric detector according to claim 1, characterized in that: The grafting modification method is to immerse the substrate and the structural color nano film coated on the substrate in a modification reagent solution and react at 25° C. for 5 to 10 minutes.

3. The glucose colorimetric detector according to claim 1 or 2, characterized in that: The modification reagent used for graft modification is one of Alizarin Red S, 6,7-dihydroxynaphthalene-2-sulfonate sodium, 3,4-dihydroxyphenylacetic acid, 3,4-dihydroxybenzoic acid or catechol-3,5-disulfonate sodium, and the cis-dihydroxy group in the modification reagent is covalently bonded to the boric acid group in the copolymer.

4. The glucose colorimetric detector according to claim 1, characterized in that: The thickness of the structural color nano film of the glucose colorimetric detector is 200-600 nm in air and 300-1500 nm in aqueous solution, wherein: The thickness of the organic nano gel layer of the structural color nano film in the air is 30-150nm, and the thickness in the aqueous solution is 80-400nm; the thickness of the inorganic nano oxide layer in the air and in water is 30-150nm.

5. The glucose colorimetric detector according to claim 1, characterized in that: The number of stacking of the organic nano gel layer and the inorganic nano oxide layer in the structural color nano film is 1 to 4.

6. The method for preparing the glucose colorimetric detector according to any one of claims 1 to 5, characterized in that: The steps include: ① The nanogel emulsion containing the copolymer is prepared by the reverse microemulsion method, and then the organic nanogel dispersion containing the copolymer is prepared by demulsification, dialysis and dispersion; ② Weighing inorganic nano-oxide and dispersing it in water or ethanol aqueous solution to prepare inorganic oxide nano-particle dispersion; ③ Spin-coat or spray-coat the organic nanogel dispersion containing the copolymer obtained in step ① on the substrate, heat and dry to obtain an organic nanogel layer; then spin-coat or spray-coat the inorganic oxide nanoparticle dispersion obtained in step ② on the organic nanogel layer, heat and dry to obtain a structural color nanofilm coated on the substrate; ④ Immerse the structural color nanofilm obtained in step ③ together with the substrate into the modified reagent solution for reaction to obtain a high-sensitivity rapid glucose colorimetric detector.

7. The preparation method according to claim 6, characterized in that: The organic nanogel dispersion containing the copolymer and the inorganic oxide nanoparticle dispersion can be alternately spin-coated or spray-coated on the structural color nanofilm obtained in step ③ in sequence, and the above steps can be repeated to obtain an organic-inorganic composite structural color nanofilm with a multilayer heterogeneous structure coated on the substrate.

8. The preparation method according to claim 6, characterized in that: In the step ①, the mass fraction of the organic nanogel dispersion containing the copolymer is 1% to 4%, wherein the average particle size of the copolymer in toluene is 60 to 120 nm, and the average particle size in aqueous solution is 600 to 1500 nm; In the step ②, the mass fraction of the inorganic oxide nanoparticle dispersion is 1% to 4%, wherein the particle size of the inorganic oxide nanoparticles in water is 20 to 50 nm; In the step ④, the concentration of the modification reagent solution is 0.001-1 mM, and the reagent required to dissolve the modification reagent is a phosphate buffer solution with a pH of 7.

4.

9. The preparation method according to claim 6, characterized in that: In the step ③, the heating and drying conditions are drying at 100-200° C. for 3-15 min; In step ④, the reaction condition is to react at 25° C. for 5 to 10 minutes.

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