Redox complex as well as preparation method and application thereof

Abstract

According to the redox complex and the preparation method and application thereof provided by the embodiment of the invention, the redox complex contains a brand-new bridging type biimidazole structure, the structure of the bridging type biimidazole ring contains two nitrogen atoms containing reactive hydrogen, the structure of the bridging type biimidazole ring is fixed, cis-trans isomerism interconversion of biimidazole is prevented, the biimidazole is complexed with transition metal to form the complex, and the stability of the complex is improved. The efficiency and stability of the complex are greatly improved, so that when the redox complex is used as an electron mediator in a sensor, the redox complex has lower oxidation potential, and the service life of the sensor is greatly prolonged.

Description

Technical Field

[0001] The present application relates to the field of medical diagnosis technology, and in particular to a redox complex and a preparation method and application thereof. Background Art

[0002] The first generation technology of continuous blood glucose monitoring sensor uses oxygen as electron mediator. Glucose is oxidized by glucose oxidase to produce hydrogen peroxide. The reduction of hydrogen peroxide on the electrode causes electron transfer to form a current, thereby calculating the glucose content in the monitored liquid according to the magnitude of the current. In other biosensors, for example, electrochemical sensors such as lactic acid, uric acid, blood lipids and blood ketones, the content of biological substances in the liquid is also calculated by the magnitude of the current. In the related art, a ligand complex of a transition metal coordinated by a biimidazole acts as a medium for electron transfer. However, the existing ligand complex of a transition metal coordinated by a biimidazole is a five-ring structure, and there are phenomena such as low complexation efficiency or decomplexation, poor stability, and a short service life of the sensor. It should be noted that the above content is not necessarily the prior art, nor is it used to limit the scope of patent protection of this application. Summary of the invention

[0003] The embodiments of the present application provide a redox complex and a preparation method and application thereof to solve or alleviate one or more technical problems raised above.

[0004] As one aspect of an embodiment of the present application, an embodiment of the present application provides a redox complex, the structural formula of the redox complex is shown in Formula I:

[0005]

[0006] In Formula I, R is a C1-4 alkane chain; X is one of hydroxyl, amino, vinyl, alkynyl, azide, cyano, carboxyl, hydroxymethyl, mercapto, and isocyanate; R 1 , R 2 , R 3 and R 4 is hydrogen or alkyl; M is a transition metal; n is the number of positive ions; A is a counter ion; the structural formula of L2 is shown in Formula II:

[0007]

[0008] In formula II, R 5 is a C1-4 alkane chain or an o-disubstituted benzene ring; R 10 It is H, -CH3 or -CH2CH3.

[0009] Optionally, the transition metal is one of iron, cobalt, ruthenium, osmium and vanadium.

[0010] Optionally, the counter ion is chloride or hexafluorophosphate.

[0011] On the other hand, this embodiment also provides a method for preparing a redox complex, comprising the following steps:

[0012] Performing a first reaction between biimidazole and a first organic compound to obtain a first bridged biimidazole, wherein the first organic compound comprises one of 2,3-dibromo-1-propanol, 1,3-dibromo-2-propanol, and 1,4-dibromo-2-butanol;

[0013] The biimidazole is subjected to a second reaction with a second organic compound to obtain a second bridged biimidazole, wherein the second organic compound comprises one of 1,2-dibromoethane, 1,3-dibromopropane, 1,4-dibromobutane and 1,2-di(bromomethyl)benzene;

[0014] The first bridge-ring biimidazole and the second bridge-ring biimidazole are complexed with a transition metal to undergo a third reaction to obtain the redox complex.

[0015] Optionally, the step of subjecting the biimidazole to a first reaction with a first organic compound to obtain a first bridged biimidazole comprises:

[0016] reacting the biimidazole with one of sodium hydroxide, sodium hydride or methyl p-toluenesulfonate to obtain a first intermediate product;

[0017] The first intermediate product is reacted with the first organic matter to obtain the first bridged biimidazole.

[0018] Optionally, the step of subjecting the biimidazole to a second reaction with a second organic compound to obtain a second bridged biimidazole comprises:

[0019] reacting the biimidazole with one of sodium hydroxide, sodium hydride or methyl p-toluenesulfonate to obtain a second intermediate product;

[0020] The second intermediate product is reacted with the second organic matter to obtain the second bridged biimidazole.

[0021] Optionally, the first bridge-ring biimidazole and the second bridge-ring biimidazole are subjected to a third reaction by complexing with a transition metal to obtain the redox complex, comprising:

[0022] The second bridged biimidazole and potassium hexachloroosmate are reacted in an organic solvent to obtain a third intermediate product, wherein the reaction temperature is 120° C. to 150° C. and the reaction time is 12 h to 36 h;

[0023] The third intermediate product is reacted with the first biimidazole to obtain a fourth intermediate product; wherein the reaction temperature is 120° C. to 150° C., and the reaction time is 12 h to 36 h;

[0024] The fourth intermediate product is oxidized in air and then reacted with ammonium hexafluorophosphate to obtain the redox complex, wherein the oxidation time is 12 hours to 36 hours.

[0025] Optionally, the molar ratio of the first bridge-ring biimidazole to the second bridge-ring biimidazole is (1-4): (1.3-3).

[0026] On the other hand, the present invention also provides a method for preparing a sensing layer, comprising the following steps:

[0027] Dissolving the redox complex, oxidase and corresponding backbone polymer in a HEPES buffer solution to obtain a sensing layer solution;

[0028] The sensing layer solution is coated on the surface of the electrode to form the sensing layer.

[0029] On the other hand, the present invention also provides a method for preparing a sensor electrode, comprising the following steps:

[0030] Spraying, dripping or dipping the prepared sensing layer onto the surface of the carbon electrode;

[0031] The outer film layer is sprayed or dipped onto the surface of the carbon electrode containing the sensing layer to prepare the sensing electrode.

[0032] The above technical solution adopted in the embodiment of the present application may have the following advantages:

[0033] The present invention provides a redox complex and a preparation method and application thereof. The redox complex comprises a brand-new bridged biimidazole structure, which fixes the structure of the imidazole ring by bridging two nitrogen atoms containing active hydrogen, prevents the biimidazole from cis-trans isomerization, forms a complex when complexed with a transition metal, and greatly improves the efficiency and stability of the complex. Therefore, when the redox complex is used as an electron mediator in a sensor, it has a lower oxidation potential and greatly improves the service life of the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in the present application and should not be regarded as limiting the scope of the present application.

[0035] Figure 1 The cyclic voltammogram corresponding to the redox complex prepared in Examples 4-8 provided in the present application;

[0036] Figure 2A graph showing the relationship between glucose concentration and current intensity provided in the embodiments of the present application;

[0037] Figure 3 A graph showing the change in current intensity of the sensing electrode over time provided in an embodiment of the present application. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other in the absence of conflict. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0039] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0040] To facilitate those skilled in the art to understand the technical solutions provided in the embodiments of the present application, the relevant technologies are described below:

[0041] The existing ligand complex of transition metal coordinated by biimidazole is a five-ring structure, which has the problems of low complexation efficiency or decomplexation, poor stability, and leads to a short service life of the sensor.

[0042] To this end, the embodiments of the present application provide a redox complex and a preparation method and application thereof. Based on this, when the redox complex is used as an electron mediator in a sensor, it has a lower oxidation potential and greatly improves the service life of the sensor. See below for details.

[0043] Hereinafter, exemplary embodiments according to the present application will be described in more detail with reference to the accompanying drawings. It should be noted that these exemplary embodiments can be implemented in many different forms and should not be construed as being limited to the embodiments described herein.

[0044] Example 1

[0045] The present application provides a redox complex, the structural formula of which is shown in Formula I:

[0046]

[0047] In formula I, R is a C1-4 alkane chain; X is one of hydroxyl, amino, vinyl, alkynyl, azide, cyano, carboxyl, hydroxymethyl, mercapto, and isocyanate groups. These active groups react with the polymer resin to fix it on the polymer skeleton through chemical bonds, thereby preventing the redox complex from migrating and diffusing into human tissue fluid, thereby further improving the use mission and safety of the prepared sensing electrode when the redox complex is used as an electron mediator. 1 , R 2 , R 3 and R 4 is hydrogen or alkyl; M is a transition metal; n is the number of positive ions; A is a counter ion; the structural formula of L2 is shown in Formula II:

[0048]

[0049] In formula II, R 5 is a C1-4 alkane chain or an o-disubstituted benzene ring; R 10 is H, -CH3 or -CH2CH3. Wherein, the transition metal is one of iron, cobalt, ruthenium, osmium and vanadium; and the counter ion is chlorine or hexafluorophosphate.

[0050] In an embodiment of the present application, a redox complex and a preparation method and application thereof are provided. The redox complex contains a brand-new bridged biimidazole structure, which fixes the structure of the imidazole ring by bridging two nitrogen atoms containing active hydrogen, prevents the cis-trans isomerization of biimidazole, and forms a complex when complexed with a transition metal, thereby greatly improving the efficiency and stability of the complex. Therefore, when the redox complex is used as an electron mediator in a sensor, it has a lower oxidation potential and greatly improves the service life of the sensor.

[0051] Example 2

[0052] The present application provides a redox complex, the structural formula of which is shown in Formula III:

[0053]

[0054] Wherein, X is an active group such as hydroxyl, amino, vinyl, alkynyl, azide, cyano, carboxyl, hydroxymethyl, mercapto or isocyanate; m is 2, 3, 4, 6 or 8; R 10 It is H, -CH3 or -CH2CH3.

[0055] In some embodiments, the structural formula of the redox complex can also be shown as formula (1) to (21):

[0056]

[0057]

[0058] When the redox complex is used as an electron mediator in a biosensor, it has better chemical stability, lower oxidation peak, better linear range and longer sensitivity stability.

[0059] Example 3

[0060] The present invention also provides a method for preparing a redox complex, comprising the following steps:

[0061] S300, performing a first reaction on biimidazole and a first organic substance to obtain a first bridged biimidazole, wherein the first organic substance comprises one of 2,3-dibromo-1-propanol, 1,3-dibromo-2-propanol, and 1,4-dibromo-2-butanol.

[0062] In some embodiments, S300 may further include:

[0063] S300A, reacting the biimidazole with one of sodium hydroxide, sodium hydride or methyl p-toluenesulfonate to obtain a first intermediate product;

[0064] S300B, reacting the first intermediate product with the first organic matter to obtain the first bridged biimidazole.

[0065] S302, performing a second reaction on the biimidazole and a second organic compound to obtain a second bridged biimidazole, wherein the second organic compound comprises one of 1,2-dibromoethane, 1,3-dibromopropane, 1,4-dibromobutane and 1,2-di(bromomethyl)benzene.

[0066] In some embodiments, S302 may further include:

[0067] S302A, reacting the biimidazole with one of sodium hydroxide, sodium hydride or methyl p-toluenesulfonate to obtain a second intermediate product;

[0068] S302B, reacting the second intermediate product with the second organic matter to obtain the second bridged biimidazole.

[0069] S304, subjecting the first bridge-ring biimidazole and the second bridge-ring biimidazole to a third reaction by complexing with a transition metal to obtain the redox complex, wherein the molar ratio of the first bridge-ring biimidazole to the second bridge-ring biimidazole is (1-4):(1.3-3).

[0070] In some embodiments, S304 may further include:

[0071] S304A, reacting the second bridged biimidazole and potassium hexachloroosmate in an organic solvent to obtain a third intermediate product, wherein the reaction temperature is 120° C. to 150° C. and the reaction time is 12 h to 36 h;

[0072] S304B, reacting the third intermediate product with the second bridged biimidazole to obtain a fourth intermediate product; wherein the reaction temperature is 120° C. to 150° C., and the reaction time is 12 h to 36 h;

[0073] S304C, oxidizing the fourth intermediate product in air, and then reacting with ammonium hexafluorophosphate to obtain the redox complex, wherein the oxidation time is 12 hours to 36 hours.

[0074] Example 4

[0075] The present application example takes the redox complex represented by the structural formula (1) in Example 2 as an example to further illustrate the preparation method of the redox complex.

[0076] S400, Synthesis of Compound 1,1'-Bis(1-hydroxymethyl)methylene-2,2'-biimidazole

[0077] Add biimidazole (0.7g, 5.2mmol) and N,N-dimethylformamide (10mL) to the reaction bottle, stir and mix evenly, then add sodium hydroxide (0.46g, 11.5mmol), and continue stirring at room temperature for 0.5 hours. Then add 2,3-dibromo-1-propanol (1.2g, 5.5mmol), and continue stirring at room temperature for 24 hours. The reaction was cooled to room temperature, filtered to remove insoluble solid particles, and the filtrate was evaporated to remove N,N-dimethylformamide. The crude product was ultrasonically washed three times with hot acetonitrile, the washing liquid was collected, and the acetonitrile was evaporated to obtain a slightly yellow solid powder (0.36g, 36.3%). The H NMR spectrum data of the obtained product are as follows:

[0078] 1 H NMR (400MHz, (CD3)2SO) δ (ppm): 7.30 (d, 2H), 7.02 (d, 2H), 4.40 (d, 2H), 3.95-3.88 (m, 1H), 4.20-4.16 (d, 2H), 2.74-2.73 (d, 1H).

[0079] S402, Synthesis of Compound 1,1'-Dimethylene-2,2'-Biimidazole

[0080] Add biimidazole (1.0g, 7.43mmol) and N,N-dimethylformamide (10mL) to the reaction bottle, stir and mix evenly, then add sodium hydroxide (0.66g, 16.3mmol), and continue stirring at room temperature for 0.5 hours. Then add 1,2-dibromoethane (1.54g, 8.17mmol), and continue stirring at room temperature for 24 hours. The reaction was cooled to room temperature, filtered to remove insoluble solid particles, and the filtrate was evaporated to remove N,N-dimethylformamide. The crude product was ultrasonically washed three times with hot acetonitrile, the washing liquid was collected, and the acetonitrile was evaporated to obtain a slightly yellow solid powder (0.42g, 35%). The H NMR spectrum data of the obtained product are as follows:

[0081] 1 H NMR (400MHz, (CD3)2SO) δ (ppm): 7.30 (d, 2H), 7.01 (d, 2H), 4.30 (s, 4H).

[0082] S404, Synthesis of Redox Complex (1)

[0083] Add 1,1'-dimethyl-2,2'-biimidazole (0.2 g, 1.2 mmol) and potassium hexachloroosmate (0.33 g, 0.7 mmol) to the reaction tube, add 10 mL of ethylene glycol, stir to mix evenly, stir at 140 ° C for 24 hours, then add a mixture of 1,1'-bis(2-hydroxymethyl)methylene-2,2'-biimidazole (0.18 g, 0.9 mmol) and 5 mL of ethylene glycol, and continue stirring for 24 hours.

[0084] The reaction mixture was cooled to room temperature, filtered to remove insoluble solid impurities, and the filtrate was added with 20 mL of deionized water, and stirred in an open beaker at room temperature for 24 hours to oxidize it. The oxidized solution was then added dropwise to 100 mL of ammonium hexafluorophosphate (10.0 g) solution to precipitate, and filtered to obtain a brown-black solid powder (0.16 g, 26.7%), i.e., redox complex (1).

[0085] Example 5

[0086] The present application example takes the redox complex represented by the structural formula (2) in Example 2 as an example to further illustrate the preparation method of the redox complex.

[0087] S500, Synthesis of Compound 1,1'-Tris(2-hydroxy)methylene-2,2'-biimidazole

[0088] Add biimidazole (0.7g, 5.2mmol) and N,N-dimethylformamide (10mL) to the reaction bottle, stir and mix evenly, then add sodium hydroxide (0.46g, 11.5mmol), and continue stirring at room temperature for 0.5 hours. Then add 1,3-dibromo-2-propanol (1.2g, 5.5mmol), and continue stirring at room temperature for 24 hours. The reaction was cooled to room temperature, filtered to remove insoluble solid particles, and the filtrate was evaporated to remove N,N-dimethylformamide. The crude product was ultrasonically washed three times with hot acetonitrile, the washing liquid was collected, and the acetonitrile was evaporated to obtain a slightly yellow solid powder (0.46g, 46%). The H NMR spectrum data of the obtained product are as follows:

[0089] 1 H NMR (400MHz, (CD3)2SO) δ (ppm): 7.30 (d, 2H), 7.02 (d, 2H), 4.06 (d, 4H), 3.85-3.78 (m, 1H), 2.75-2.73 (d, 1H).

[0090] S502, Synthesis of Compound 1,1'-Trimethylene-2,2'-Biimidazole

[0091] Add biimidazole (1.0g, 7.43mmol) and N,N-dimethylformamide (10mL) to the reaction bottle, stir and mix evenly, then add sodium hydroxide (0.66g, 16.3mmol), and continue stirring at room temperature for 0.5 hours. Then add 1,3-dibromopropane (1.65g, 8.17mmol), and continue stirring at room temperature for 24 hours. The reaction was cooled to room temperature, filtered to remove insoluble solid particles, and the filtrate was evaporated to remove N,N-dimethylformamide. The crude product was ultrasonically washed three times with hot acetonitrile, the washing liquid was collected, and the acetonitrile was evaporated to obtain a slightly yellow solid powder (0.32g, 25.3%). The H NMR spectrum data of the obtained product are as follows:

[0092] 1 H NMR (400MHz, (CD3)2SO) δ (ppm): 7.30 (d, 2H), 7.01 (d, 2H), 4.40-4.32 (m, 4H), 2.45-2.41 (m, 2H).

[0093] S504, Synthesis of Redox Complex (2)

[0094] Add 1,1'-trimethylene-2,2'-biimidazole (0.2 g, 1.2 mmol) and potassium hexachloroosmate (0.33 g, 0.7 mmol) to the reaction tube, add 10 mL of ethylene glycol, stir to mix evenly, stir at 140 ° C for 24 hours, then add a mixture of 1,1'-tri(2-hydroxy)methylene-2,2'-biimidazole (0.18 g, 0.9 mmol) and 5 mL of ethylene glycol, and continue stirring for 24 hours.

[0095] The reaction mixture was cooled to room temperature, filtered to remove insoluble solid impurities, and the filtrate was added with 20 mL of deionized water, and stirred in an open beaker at room temperature for 24 hours to oxidize it. The oxidized solution was then added dropwise to 100 mL of ammonium hexafluorophosphate (10.0 g) solution to precipitate, and filtered to obtain a brown-black solid powder (0.21 g, 35%), i.e., redox complex (2).

[0096] Example 6

[0097] The present application example takes the redox complex represented by the structural formula (3) in Example 2 as an example to further illustrate the method for preparing the redox complex.

[0098] S600, Synthesis of Compound 1,1'-Tetra(2-hydroxy)methylene-2,2'-biimidazole

[0099] Add biimidazole (0.7g, 5.2mmol) and N,N-dimethylformamide (10mL) to the reaction bottle, stir and mix evenly, then add sodium hydroxide (0.46g, 11.5mmol), and continue stirring at room temperature for 0.5 hours. Then add 1,4-dibromo-2-butanol (1.28g, 5.5mmol), and continue stirring at room temperature for 24 hours. The reaction was cooled to room temperature, filtered to remove insoluble solid particles, and the filtrate was evaporated to remove N,N-dimethylformamide. The crude product was ultrasonically washed three times with hot acetonitrile, the washing liquid was collected, and the acetonitrile was evaporated to obtain a slightly yellow solid powder (0.31g, 29.2%). The H NMR spectrum data of the obtained product are as follows:

[0100] 1 H NMR (400MHz, (CD3)2SO) δ (ppm): 7.30 (d, 2H), 7.02 (d, 2H), 5.85-5.78 (m, 1H), 4.56 (s, 1H), 3.95-3.88 (m, 2H), 2.22-2.18 (m, 2H), 2.05-1.93 (m, 2H).

[0101] S602, Synthesis of Compound 1,1'-Tetramethylene-2,2'-Biimidazole

[0102] Add biimidazole (1.0g, 7.43mmol) and N,N-dimethylformamide (10mL) to the reaction bottle, stir and mix evenly, then add sodium hydroxide (0.66g, 16.3mmol), and continue stirring at room temperature for 0.5 hours. Then add 1,4-dibromobutane (1.76g, 8.17mmol), and continue stirring at room temperature for 24 hours. The reaction was cooled to room temperature, filtered to remove insoluble solid particles, and the filtrate was evaporated to remove N,N-dimethylformamide. The crude product was ultrasonically washed three times with hot acetonitrile, the washing liquid was collected, and the acetonitrile was evaporated to obtain a slightly yellow solid powder (0.44g, 31.5%). The H NMR spectrum data of the obtained product are as follows:

[0103] 1 H NMR (400MHz, (CD3)2SO) δ (ppm): 7.30 (d, 2H), 7.01 (d, 2H), 3.90-3.84 (m, 4H), 1.95-1.78 (m, 4H).

[0104] S604, Synthesis of Redox Complex (3)

[0105] Add 1,1'-tetramethylene-2,2'-biimidazole (0.21 g, 1.1 mmol) and potassium hexachloroosmate (0.33 g, 0.7 mmol) to the reaction tube, add 10 mL of ethylene glycol, stir to mix evenly, stir at 160 ° C for 24 hours, then add a mixture of 1,1'-tetra(2-hydroxy)methylene-2,2'-biimidazole (0.19 g, 0.9 mmol) and 5 mL of ethylene glycol, and continue stirring for 24 hours.

[0106] The reaction mixture was cooled to room temperature, filtered to remove insoluble solid impurities, and the filtrate was added with 20 mL of deionized water, and stirred in an open beaker at room temperature for 24 hours to oxidize it. The oxidized solution was then added dropwise to 100 mL of ammonium hexafluorophosphate (10.0 g) solution to precipitate, and filtered to obtain a brown-black solid powder (0.21 g, 33.9%), i.e., redox complex (3).

[0107] Example 7

[0108] The present application example takes the redox complex represented by the structural formula (5) in Example 2 as an example to further illustrate the preparation method of the redox complex.

[0109] S700, Synthesis of Compound 1,1'-Tris(2-hydroxy)methylene-2,2'-biimidazole

[0110] This step is the same as S502 in Example 5.

[0111] S702, Synthesis of Compound 1,1'-Dimethylene-2,2'-Biimidazole

[0112] This step is the same as S404 in Example 4.

[0113] S704, Synthesis of redox complex (5)

[0114] Add 1,1'-dimethyl-2,2'-biimidazole (0.2 g, 1.2 mmol) and potassium hexachloroosmate (0.33 g, 0.7 mmol) to the reaction tube, add 10 mL of ethylene glycol, stir to mix evenly, stir at 140 ° C for 24 hours, then add a mixture of 1,1'-tri(2-hydroxy)methylene-2,2'-biimidazole (0.18 g, 0.9 mmol) and 5 mL of ethylene glycol, heat to 160 ° C, and continue stirring for 24 hours.

[0115] The reaction mixture was cooled to room temperature, filtered to remove insoluble solid impurities, and the filtrate was added with 20 mL of deionized water, and stirred in an open beaker at room temperature for 24 hours to oxidize it. The oxidized solution was then added dropwise to 100 mL of ammonium hexafluorophosphate (10.0 g) solution to precipitate, and filtered to obtain a brown-black solid powder (0.16 g, 26.7%), i.e., redox complex (5).

[0116] Example 8

[0117] The present application example takes the redox complex represented by the structural formula (13) in Example 2 as an example to further illustrate the preparation method of the redox complex.

[0118] S800, Synthesis of Compound 1,1'-Bis(1-hydroxymethyl)methylene-2,2'-biimidazole

[0119] This step is the same as S401 in Example 4.

[0120] S802, Synthesis of Compound 1,1'-α,α'-dibenzyl-2,2'-biimidazole

[0121] Add biimidazole (1.0g, 7.43mmol) and N,N-dimethylformamide (10mL) to the reaction bottle, stir and mix evenly, then add sodium hydroxide (0.66g, 16.3mmol), and continue stirring at room temperature for 0.5 hours. Then add 1,2-di(bromomethyl)benzene (2.16g, 8.17mmol), and continue stirring at room temperature for 24 hours. The reaction was cooled to room temperature, filtered to remove insoluble solid particles, and the filtrate was evaporated to remove N,N-dimethylformamide. The crude product was ultrasonically washed three times with hot acetonitrile, the washing liquid was collected, and the acetonitrile was evaporated to obtain a slightly yellow solid powder (0.54g, 30%). The H NMR spectrum data of the obtained product are as follows:

[0122] 1H NMR (400MHz, (CD3)2SO) δ (ppm): 7.34 (d, 2H), 7.05 (d, 2H), 7.15-7.11 (m, 4H), 5.25 (d, 4H).

[0123] S804, Synthesis of redox complex (13)

[0124] Add 1,1'-α,α'-dibenzyl-2,2'-biimidazole (0.28 g, 1.2 mmol) and potassium hexachloroosmate (0.33 g, 0.7 mmol) to the reaction tube, add 10 mL of ethylene glycol, stir to mix evenly, stir at 160 ° C for 24 hours, then add a mixture of 1,1'-bis(1-hydroxymethyl)methylene-2,2'-biimidazole (0.18 g, 0.9 mmol) and 5 mL of ethylene glycol, and continue stirring for 24 hours.

[0125] The reaction mixture was cooled to room temperature, filtered to remove insoluble solid impurities, and the filtrate was added with 20 mL of deionized water, and stirred in an open beaker at room temperature for 24 hours to oxidize it. The oxidized solution was then added dropwise to 100 mL of ammonium hexafluorophosphate (10.0 g) solution to precipitate, and filtered to obtain a brown-black solid powder (0.16 g, 23.5%), i.e., redox complex (13).

[0126] Example 9

[0127] The present application example takes the sensing layer of a glucose electrochemical sensor as an example to further illustrate the method for preparing the sensing layer.

[0128] 1. Preparation of Sensing Layer of Glucose Electrochemical Sensor

[0129] The present application also provides a method for preparing a glucose electrochemical sensor sensing layer, comprising the following steps:

[0130] S900, dissolving the redox complex, glucose oxidase and poly(glycidyl methacrylate) prepared in Examples 4-8 in a HEPES buffer solution to obtain a sensing layer solution. In other embodiments, if other sensing layers need to be prepared, such as lactic acid, uric acid, blood lipid and blood ketone sensing layers, the glucose oxidase needs to be replaced with a corresponding biological enzyme.

[0131] Specifically, glucose oxidase (7.0 mg), poly(glycidyl methacrylate) (1.0 g) and the redox complex prepared in the above example were added to 0.5 mL of HEPES buffer solution, and the mixture was mixed evenly by an oscillator to obtain a sensing layer solution.

[0132] S902, coating the sensing layer solution on the electrode surface to form the glucose sensing layer.

[0133] Specifically, 3uL to 3mm thick sensing layer solution was dripped onto a clean glassy carbon electrode on the surface of the carbon printed electrode using a pipette and placed at room temperature for 48 hours to form a sensing film layer on the glassy carbon electrode. After it was completely dried, the glucose sensing layers A1-A5 were obtained.

[0134] 2. Redox peak potential test of the sensing layer of glucose electrochemical sensor

[0135] The A1 to A5 sensing layers were immersed in a standard PBS buffer (pH 7.4, 150 mM NaCl), and the voltage range was set from -1.0 V to 1.0 V, the scan rate was 0.1 V / s, and the number of cycles was 5 times.

[0136] Figure 1 is the cyclic voltammogram corresponding to the redox complex prepared in Examples 4-8 provided in the present application. Figure 1 It can be seen that the potentials of all the redox complexes prepared in Examples 4-8 are less than 10 mV. In this way, electrochemical catalytic oxidation of glucose can be achieved at a relatively low potential, avoiding interference with the results of blood glucose monitoring caused by other biological reactions in the human body and the oxidation process of glucose under high potential conditions, thereby improving the selectivity and accuracy of blood glucose monitoring.

[0137] Example 10

[0138] The present application example takes a glucose electrochemical sensor electrode as an example to further illustrate a method for preparing a glucose electrochemical sensor electrode.

[0139] 1. Preparation of Glucose Electrochemical Sensing Electrode

[0140] The present application also provides a method for preparing a glucose electrochemical sensor electrode, comprising the following steps:

[0141] S100, spraying, dripping or dipping the sensing layer prepared in Example 9 onto the surface of the carbon electrode;

[0142] S102, spraying or dipping the outer film layer onto the surface of the carbon electrode containing the sensing layer; and preparing the glucose electrochemical sensing electrode.

[0143] Specifically, the sensing layer solution prepared in Example 9 is dripped, sprayed or dipped onto the surface of the carbon printed electrode. The sensing layer solution is on the glassy carbon electrode. As the solvent evaporates, various compounds are cross-linked to gradually form a film layer. After drying at room temperature for 48 hours, an outer film layer polymer is coated on the electrode surface by dipping and pulling, and continued to dry at room temperature for 48 hours to obtain a glucose sensing electrode.

[0144] The glucose sensing electrode has a lower oxidation peak working potential, long-term sensitivity stability, and good safety performance, because the redox complex proposed in the embodiment of the present application can react with the polymer resin through the active groups in its structure, so that it is fixed on the polymer skeleton through chemical bonds, thereby preventing the redox complex from migrating and diffusing into the human tissue fluid, thereby further improving the use mission and safety of the sensing electrode. In another embodiment of the present invention, the sensing electrode can be a glucose electrochemical sensing electrode, a uric acid electrochemical sensing electrode, a blood ketone body electrochemical sensing electrode or a lactic acid electrochemical sensing electrode.

[0145] 2. Sensor electrode linearity test

[0146] The sensing electrode was immersed in a standard PBS buffer (pH 7.4, 150 mM NaCl), followed by an initial pulse of 1.1 volts for 360 seconds. The sensor was held at 0.6 V for the remainder of the measurement. After waiting for 10 minutes, the sensor reached a constant background, and 5.0, 10.0, 15.0, 20.0, 25.0, 30.0, and 40.0 mM concentrations of glucose were added to the solution to measure the linearity of the reaction. After each addition of glucose, the solution was allowed to equilibrate for 3 minutes. The solution was continuously stirred to make its concentration uniform. Figure 2 is a graph showing the relationship between glucose concentration and current intensity provided in the embodiment of the present application; Figure 2 It can be seen that the sensor has very good linearity between 5-40mM concentration. In other words, all the electrons generated during glucose oxidation are quickly transferred to the electrode, which improves the transfer efficiency of the electrons generated during glucose oxidation and thus improves the sensitivity of blood glucose monitoring.

[0147] 3. Sensing electrode stability test

[0148] The sensing electrode was immersed in 3mM standard glucose solution to test its stability. Figure 3 The relationship diagram between the test time and the current intensity provided by this application 4 is as follows: Figure 3 It can be seen from the figure that the average signal attenuation of the sensor every 24 hours within 6 days is only 0.5%, indicating that the sensor film prepared by the present invention has good stability.

[0149] The above description is only used to understand the method and core idea of ​​the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made to the present invention without departing from the principles of the present invention. These improvements and modifications also fall within the scope of protection of the rights of the present invention.

Claims

1. A redox complex, characterized in that The structural formula of the redox complex is shown in Formula I: In Formula I, R is a C1-4 alkane chain; X is one of hydroxyl, amino, vinyl, alkynyl, azide, cyano, carboxyl, hydroxymethyl, mercapto, and isocyanate; R 1 , R 2 , R 3 and R 4 is hydrogen or alkyl; M is a transition metal; n is the number of positive ions; A is a counter ion; the structural formula of L2 is shown in Formula II: In formula II, R 5 is a C1-4 alkane chain or an o-disubstituted benzene ring; R 10 It is H, -CH3 or -CH2CH3.

2. The redox complex according to claim 1, characterized in that The transition metal is one of iron, cobalt, ruthenium, osmium and vanadium.

3. The redox complex according to claim 2, characterized in that The counter ion is chloride or hexafluorophosphate.

4. The method for preparing the redox complex according to any one of claims 1 to 3, characterized in that: The following steps are involved: Performing a first reaction between biimidazole and a first organic compound to obtain a first bridged biimidazole, wherein the first organic compound comprises one of 2,3-dibromo-1-propanol, 1,3-dibromo-2-propanol, and 1,4-dibromo-2-butanol; The biimidazole is subjected to a second reaction with a second organic compound to obtain a second bridged biimidazole, wherein the second organic compound comprises one of 1,2-dibromoethane, 1,3-dibromopropane, 1,4-dibromobutane and 1,2-di(bromomethyl)benzene; The first bridge-ring biimidazole and the second bridge-ring biimidazole are complexed with a transition metal to undergo a third reaction to obtain the redox complex.

5. The preparation method according to claim 4, characterized in that: The step of performing a first reaction between the biimidazole and the first organic compound to obtain the first bridged biimidazole comprises: reacting the biimidazole with one of sodium hydroxide, sodium hydride or methyl p-toluenesulfonate to obtain a first intermediate product; The first intermediate product is reacted with the first organic matter to obtain the first bridged biimidazole.

6. The preparation method according to claim 4, characterized in that: The step of performing a second reaction between the biimidazole and the second organic compound to obtain a second bridged biimidazole comprises: reacting the biimidazole with one of sodium hydroxide, sodium hydride or methyl p-toluenesulfonate to obtain a second intermediate product; The second intermediate product is reacted with the second organic matter to obtain the second bridged biimidazole.

7. The preparation method according to claim 4, characterized in that: The first bridge ring biimidazole and the second bridge ring biimidazole are subjected to a third reaction by complexing with a transition metal to obtain the redox complex, comprising: The second bridged biimidazole and potassium hexachloroosmate are reacted in an organic solvent to obtain a third intermediate product, wherein the reaction temperature is 120° C. to 150° C. and the reaction time is 12 h to 36 h; The third intermediate product is reacted with the first bridge-ring biimidazole to obtain a fourth intermediate product; wherein the reaction temperature is 120° C. to 150° C., and the reaction time is 12 h to 36 h; The fourth intermediate product is oxidized in air and then reacted with ammonium hexafluorophosphate to obtain the redox complex, wherein the oxidation time is 12 hours to 36 hours.

8. The preparation method according to claim 4, characterized in that: The molar ratio of the first bridge ring biimidazole to the second bridge ring biimidazole is (1-4): (1.3-3).

9. A method for preparing a sensing layer, characterized in that: The following steps are involved: Dissolving the redox complex according to any one of claims 1 to 3, the oxidase and the corresponding backbone polymer in a HEPES buffer solution to obtain a sensing layer solution; The sensing layer solution is coated on the surface of the electrode to form the sensing layer.

10. A method for preparing a sensing electrode, characterized in that: The following steps are involved: Spraying, dripping or dipping the sensing layer prepared according to claim 9 onto the surface of the carbon electrode; The outer film layer is sprayed or dipped onto the surface of the carbon electrode containing the sensing layer to prepare the sensing electrode.

Images