Redox complex and preparation method therefor and use thereof

Abstract

Embodiments of the present application provide a redox complex and a preparation method therefor and a use thereof. In a brand-new bridged biimidazole structure contained in the redox complex, imidazole ring structures are immobilized by bridging two nitrogen atoms, linked to active hydrogen, on the imidazole rings, preventing the interconversion between cis-trans isomerization of biimidazole, and the bridged biimidazole structure is complexed with a transition metal to form a complex, so that the efficiency and stability of the complex are greatly improved. Therefore, when used as an electron mediator in a sensor, the redox complex greatly prolongs the service life of the sensor while having a relatively low oxidation potential.

Description

Redox complex and its preparation method and application

[0001] This application claims priority to Chinese patent application number 202310993993.6 filed on August 8, 2023, entitled “Redox Complexes, Preparation Methods and Applications Thereof”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] 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

[0003] The first generation of continuous glucose monitoring sensor technology uses oxygen as an electron mediator. Glucose is oxidized by glucose oxidase to produce hydrogen peroxide. The reduction of hydrogen peroxide at an electrode causes electron transfer, generating an electric current. The magnitude of this current is then used to calculate the glucose content in the monitored liquid. Other biosensors, such as electrochemical sensors for lactate, uric acid, blood lipids, and blood ketones, also use current to calculate the content of biological substances in the liquid. Second generation technology replaces oxygen with a synthetic organic complex as an electron mediator, reducing the sensor's excitation voltage and significantly improving its anti-interference performance, leading to its increasing widespread application. Related technologies use ligand complexes of transition metals with biimidazoles as mediators for electron transfer. However, due to the cis-trans isomerism of biimidazoles, these ligand complexes can exhibit low complexation efficiency or decomplexation during synthesis, resulting in poor stability and a short sensor lifespan. It should be noted that the above content is not necessarily prior art and is not intended to limit the scope of patent protection of this application.

[0004] Summary of the Invention

[0005] 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.

[0006] As one aspect of the embodiments of the present application, the embodiments of the present application provide a redox complex, the structural formula of the redox complex is shown in Formula I:

[0007] 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 4is hydrogen or an alkyl group; 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:

[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] Performing a second reaction between 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-bis(bromomethyl)benzene;

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

[0015] Optionally, the step of reacting the biimidazole with the first organic compound to obtain the 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 compound 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 compound to obtain the second bridged biimidazole.

[0021] Optionally, the first bridged-ring biimidazole and the second bridged-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 bridged ring biimidazole to the second bridged ring biimidazole is (1-4): (1.3-3).

[0026] On the other hand, an embodiment of the present application further 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, an embodiment of the present application further 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 embodiments of the present application may have the following advantages:

[0033] The present application provides a redox complex, a preparation method, and an application thereof. The redox complex contains a 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. 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 components or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in this application and should not be construed as limiting the scope of this application.

[0035] FIG1 is a cyclic voltammogram corresponding to the redox complex prepared in Examples 4-8 provided in the present application;

[0036] FIG2 is a graph showing the relationship between glucose concentration and current intensity provided in an embodiment of the present application;

[0037] FIG3 is a graph showing the change of the current intensity of the sensing electrode over time provided in an embodiment of the present application. DETAILED DESCRIPTION

[0038] In order to make the objectives, technical solutions, and advantages of this application more clearly understood, this application is further described in detail below with reference to the accompanying drawings and examples. It should be noted that the embodiments and features in the embodiments of this application can be combined with each other unless there is a conflict. This application will be described in detail below with reference to the accompanying drawings and in conjunction with the examples.

[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, for example, be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof 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 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 following describes the relevant technologies:

[0041] The 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 present invention provides a technical solution for a redox complex, its preparation method, and its application. Based on this, when used as an electron mediator in a sensor, this redox complex exhibits a low oxidation potential and significantly improves the sensor's service life. 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 may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein.

[0044] Example 1

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

[0046] 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 to the polymer backbone through chemical bonds, thereby preventing the redox complex from migrating and diffusing into human tissue fluid, thereby further improving the service life and safety of the sensor electrode prepared when the redox complex is used as an electron mediator. 1 、R 2 、R 3 and R 4 is hydrogen or an alkyl group; 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:

[0047] 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 chloride or hexafluorophosphate.

[0048] In an embodiment of the present application, a redox complex and its preparation method and application are provided. The redox complex contains a 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.

[0049] Example 2

[0050] The present invention provides a redox complex, the structural formula of which is shown in Formula III:

[0051] Wherein, X is an active group such as hydroxyl, amino, vinyl, alkynyl, azide, cyano, carboxyl, hydroxymethyl, mercapto or isocyanate; m is 2, 3 or 4; n is 2, 3, 4 or an o-disubstituted benzene ring; R 10 It is H, -CH3 or -CH2CH3.

[0052] In some embodiments, the structural formula of the redox complex can also be shown as formula (1) to (21):

[0053] 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.

[0054] Example 3

[0055] The present invention also provides a method for preparing a redox complex, comprising the following steps:

[0056] S300, performing a first reaction on a 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.

[0057] In some embodiments, S300 may further include:

[0058] S300A, reacting the biimidazole with one of sodium hydroxide, sodium hydride or methyl p-toluenesulfonate to obtain a first intermediate product;

[0059] S300B, reacting the first intermediate product with the first organic compound to obtain the first bridged biimidazole.

[0060] 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-bis(bromomethyl)benzene.

[0061] In some embodiments, S302 may further include:

[0062] S302A, reacting the biimidazole with one of sodium hydroxide, sodium hydride or methyl p-toluenesulfonate to obtain a second intermediate product;

[0063] S302B, reacting the second intermediate product with the second organic compound to obtain the second bridged biimidazole.

[0064] S304, performing a third reaction on the first bridged-ring biimidazole and the second bridged-ring biimidazole by complexing with a transition metal to obtain the redox complex, wherein the molar ratio of the first bridged-ring biimidazole to the second bridged-ring biimidazole is (1-4):(1.3-3).

[0065] In some embodiments, S304 may further include:

[0066] 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;

[0067] S304B, reacting the third intermediate product with the second bridged-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;

[0068] S304C, oxidizing the fourth intermediate product in air and reacting it with ammonium hexafluorophosphate to obtain the redox complex, wherein the oxidation time is 12 hours to 36 hours.

[0069] Example 4

[0070] The present application 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.

[0071] S400, Synthesis of Compound 5,6-Dihydrobiimidazole (1,2-a:2',1'-c)pyrazin-5-ol

[0072] Add biimidazole (0.7 g, 5.2 mmol) and N,N-dimethylformamide (10 mL) to the reaction flask and stir to mix thoroughly. Then add sodium hydroxide (0.46 g, 11.5 mmol) and continue stirring at room temperature for 0.5 hour. Then add 2,3-dibromo-1-propanol (1.2 g, 5.5 mmol) and continue stirring at room temperature for 24 hours. The reaction mixture is cooled to room temperature and filtered to remove insoluble solid particles. The filtrate is rotary evaporated to remove N,N-dimethylformamide. The crude product is ultrasonically washed three times with hot acetonitrile. The washings are collected and the acetonitrile is rotary evaporated to obtain a slightly yellow solid powder (0.36 g, 36.3%). The H NMR spectrum data of the obtained product are as follows:

[0073] 1H 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).

[0074] S402, Synthesis of Compound 5,6-Dihydrobiimidazole (1,2-a:2',1'-c)pyrazine

[0075] To the reaction flask, add biimidazole (1.0 g, 7.43 mmol) and N,N-dimethylformamide (10 mL), stir and mix until uniform, then add sodium hydroxide (0.66 g, 16.3 mmol), and continue stirring at room temperature for 0.5 hour. Then add 1,2-dibromoethane (1.54 g, 8.17 mmol), 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 rotary evaporated to remove N,N-dimethylformamide. The crude product was ultrasonically washed three times with hot acetonitrile, the washings were collected, and the acetonitrile was rotary evaporated to obtain a slightly yellow solid powder (0.42 g, 35%). The H NMR spectrum data of the obtained product are as follows:

[0076] 1 H NMR (400MHz, (CD3)2SO) δ (ppm): 7.30 (d, 2H), 7.01 (d, 2H), 4.30 (s, 4H).

[0077] S404, Synthesis of Redox Complex (1)

[0078] 5,6-dihydrobiimidazole (1,2-a:2',1'-c) pyrazine (0.2 g, 1.2 mmol) and potassium hexachloroosmate (0.33 g, 0.7 mmol) were added to the reaction tube, and 10 mL of ethylene glycol was added and stirred to mix evenly. The mixture was stirred at 140 ° C for 24 hours, and then a mixture of 5,6-dihydrobiimidazole (1,2-a:2',1'-c) pyrazine-5-ol (0.18 g, 0.9 mmol) and 5 mL of ethylene glycol was added and stirring was continued for 24 hours.

[0079] The reaction mixture was cooled to room temperature and filtered to remove insoluble solid impurities. The filtrate was added with 20 mL of deionized water and stirred in an open beaker at room temperature for 24 hours to oxidize the mixture. The oxidized solution was then added dropwise to 100 mL of ammonium hexafluorophosphate (10.0 g) solution to precipitate the mixture. The mixture was filtered to obtain a brownish-black solid powder (0.16 g, 26.7%), namely the redox complex (1).

[0080] Example 5

[0081] The present application examples take 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.

[0082] S500, Synthesis of Compound 6,7-Dihydro-5H-biimidazole (1,2-a:2',1'-c)(1,4)diazepine-6-ol

[0083] To the reaction flask, add biimidazole (0.7 g, 5.2 mmol) and N,N-dimethylformamide (10 mL), stir and mix until uniform, then add sodium hydroxide (0.46 g, 11.5 mmol), and continue stirring at room temperature for 0.5 hour. Then add 1,3-dibromo-2-propanol (1.2 g, 5.5 mmol), 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 rotary evaporated to remove N,N-dimethylformamide. The crude product was ultrasonically washed three times with hot acetonitrile, the washings were collected, and the acetonitrile was rotary evaporated to obtain a slightly yellow solid powder (0.46 g, 46%). The H NMR spectrum data of the obtained product are as follows:

[0084] 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).

[0085] S502, Synthesis of Compound 6,7-Dihydro-5H-biimidazole (1,2-a:2',1'-c)(1,4)diazepine

[0086] Add biimidazole (1.0 g, 7.43 mmol) and N,N-dimethylformamide (10 mL) to the reaction flask and stir to mix thoroughly. Then add sodium hydroxide (0.66 g, 16.3 mmol) and continue stirring at room temperature for 0.5 hour. Then add 1,3-dibromopropane (1.65 g, 8.17 mmol) and continue stirring at room temperature for 24 hours. The reaction mixture is cooled to room temperature and filtered to remove insoluble solid particles. The filtrate is rotary evaporated to remove N,N-dimethylformamide. The crude product is ultrasonically washed three times with hot acetonitrile. The washings are collected and the acetonitrile is rotary evaporated to obtain a slightly yellow solid powder (0.32 g, 25.3%). The H NMR spectrum data of the obtained product are as follows:

[0087] 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).

[0088] S504, Synthesis of Redox Complex (2)

[0089] Add 6,7-dihydro-5H-biimidazole (1,2-a: 2', 1'-c) (1,4) diazepine (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 6,7-dihydro-5H-biimidazole (1,2-a: 2', 1'-c) (1,4) diazepine-6-ol (0.18 g, 0.9 mmol) and 5 mL of ethylene glycol, and continue stirring for 24 hours.

[0090] The reaction mixture was cooled to room temperature and filtered to remove insoluble solid impurities. The filtrate was added with 20 mL of deionized water and stirred in an open beaker at room temperature for 24 hours to oxidize the mixture. The oxidized solution was then added dropwise to 100 mL of ammonium hexafluorophosphate (10.0 g) solution to precipitate the mixture. The mixture was filtered to obtain a brownish-black solid powder (0.21 g, 35%), namely, redox complex (2).

[0091] Example 6

[0092] The present application examples take the redox complex represented by the structural formula (3) in Example 2 as an example to further illustrate the preparation method of the redox complex.

[0093] S600, Synthesis of Compound 5,6,7,8-Tetrahydrobiimidazole (1,2-a:2',1'-c)(1,4)diazacyclooctan-5-ol

[0094] To the reaction flask, add biimidazole (0.7 g, 5.2 mmol) and N,N-dimethylformamide (10 mL). Stir and mix thoroughly. Then add sodium hydroxide (0.46 g, 11.5 mmol) and continue stirring at room temperature for 0.5 hour. Then add 1,4-dibromo-2-butanol (1.28 g, 5.5 mmol) and continue stirring at room temperature for 24 hours. The reaction mixture is cooled to room temperature, filtered to remove insoluble solid particles, and the filtrate is rotary evaporated to remove N,N-dimethylformamide. The crude product is ultrasonically washed three times with hot acetonitrile. The washings are collected and the acetonitrile is rotary evaporated to obtain a slightly yellow solid powder (0.31 g, 29.2%). The H NMR spectrum of the obtained product is as follows:

[0095] 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).

[0096] S602, Synthesis of Compound 5,6,7,8-Tetrahydrobiimidazole (1,2-a:2',1'-c)(1,4)diazacyclooctane

[0097] Add biimidazole (1.0 g, 7.43 mmol) and N,N-dimethylformamide (10 mL) to the reaction flask and stir to mix thoroughly. Then add sodium hydroxide (0.66 g, 16.3 mmol) and continue stirring at room temperature for 0.5 hour. Then add 1,4-dibromobutane (1.76 g, 8.17 mmol) and continue stirring at room temperature for 24 hours. The reaction mixture is cooled to room temperature and filtered to remove insoluble solid particles. The filtrate is rotary evaporated to remove N,N-dimethylformamide. The crude product is ultrasonically washed three times with hot acetonitrile. The washings are collected and the acetonitrile is rotary evaporated to obtain a slightly yellow solid powder (0.44 g, 31.5%). The H NMR spectrum data of the obtained product are as follows:

[0098] 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).

[0099] S604, Synthesis of Redox Complex (3)

[0100] Add 5,6,7,8-tetrahydrobiimidazole (1,2-a: 2', 1'-c) (1,4) diazacyclooctane (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 5,6,7,8-tetrahydrobiimidazole (1,2-a: 2', 1'-c) (1,4) diazacyclooctane-5-ol (0.19 g, 0.9 mmol) and 5 mL of ethylene glycol, and continue stirring for 24 hours.

[0101] The reaction mixture was cooled to room temperature and filtered to remove insoluble solid impurities. The filtrate was added with 20 mL of deionized water and stirred in an open beaker at room temperature for 24 hours to oxidize the mixture. The oxidized solution was then added dropwise to 100 mL of ammonium hexafluorophosphate (10.0 g) solution to precipitate the mixture. The mixture was filtered to obtain a brown-black solid powder (0.21 g, 33.9%), namely, redox complex (3).

[0102] Example 7

[0103] The present application 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.

[0104] S700, Synthesis of Compound 6,7-Dihydro-5H-biimidazole (1,2-a:2',1'-c)(1,4)diazepine-6-ol

[0105] This step is the same as S500 in Example 5.

[0106] S702, Synthesis of Compound 5,6-Dihydrobiimidazole (1,2-a:2',1'-c)pyrazine

[0107] This step is the same as S402 in Example 4.

[0108] S704, Synthesis of Redox Complex (5)

[0109] Add 5,6-dihydrobiimidazole (1,2-a:2',1'-c) pyrazine (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 6,7-dihydro-5H-biimidazole (1,2-a:2',1'-c) (1,4) diazepine-6-ol (0.18 g, 0.9 mmol) and 5 mL of ethylene glycol, heat to 160 ° C, and continue stirring for 24 hours.

[0110] The reaction mixture was cooled to room temperature and filtered to remove insoluble solid impurities. The filtrate was added with 20 mL of deionized water and stirred in an open beaker at room temperature for 24 hours to oxidize the mixture. The oxidized solution was then added dropwise to 100 mL of ammonium hexafluorophosphate (10.0 g) solution to precipitate the mixture. The mixture was filtered to obtain a brownish-black solid powder (0.16 g, 26.7%), namely, redox complex (5).

[0111] Example 8

[0112] The present application 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.

[0113] S800, Synthesis of Compound 5,6-Dihydrobiimidazole (1,2-a:2',1'-c)pyrazin-5-ol

[0114] This step is the same as S400 in Example 4.

[0115] S802, Synthesis of Compound 5,10-Dihydrobenzene(f)biimidazole(1,2-a:2',1'-c)(1,4)diazacyclooctane

[0116] To the reaction flask, add biimidazole (1.0 g, 7.43 mmol) and N,N-dimethylformamide (10 mL), stir and mix until uniform, then add sodium hydroxide (0.66 g, 16.3 mmol), and continue stirring at room temperature for 0.5 hour. Then add 1,2-bis(bromomethyl)benzene (2.16 g, 8.17 mmol), 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 rotary evaporated to remove N,N-dimethylformamide. The crude product was ultrasonically washed three times with hot acetonitrile, the washings were collected, and the acetonitrile was rotary evaporated to obtain a slightly yellow solid powder (0.54 g, 30%). The H NMR spectrum data of the obtained product are as follows:

[0117] 1 H NMR (400MHz, (CD3)2SO) δ (ppm): 7.34 (d, 2H), 7.05 (d, 2H), 7.15-7.11 (m, 4H), 5.25 (d, 4H).

[0118] S804, Synthesis of Redox Complex (13)

[0119] Add 5,10-dihydrobenzene(f)biimidazole(1,2-a:2',1'-c)(1,4)diazacyclooctane (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 5,6-dihydrobiimidazole(1,2-a:2',1'-c)pyrazin-5-ol (0.18 g, 0.9 mmol) and 5 mL of ethylene glycol, and continue stirring for 24 hours.

[0120] The reaction mixture was cooled to room temperature and filtered to remove insoluble solid impurities. The filtrate was added with 20 mL of deionized water and stirred in an open beaker at room temperature for 24 hours to oxidize the mixture. The oxidized solution was then added dropwise to 100 mL of ammonium hexafluorophosphate (10.0 g) to precipitate the mixture. Filtering the mixture yielded a brownish-black solid powder (0.16 g, 23.5%), the redox complex (13).

[0121] Example 9

[0122] The present embodiment takes the sensing layer of a glucose electrochemical sensor as an example to further illustrate the preparation method of the sensing layer.

[0123] 1. Preparation of Sensing Layer of Glucose Electrochemical Sensor

[0124] The present invention also provides a method for preparing a glucose electrochemical sensor layer, comprising the following steps:

[0125] S900: Dissolve the redox complex prepared in Examples 4-8, glucose oxidase, and poly(glycidyl methacrylate) in a HEPES buffer solution to obtain a sensing layer solution. In other embodiments, if other sensing layers are desired, such as lactate, uric acid, blood lipid, or blood ketone sensing layers, the glucose oxidase may be replaced with a corresponding biological enzyme.

[0126] 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 uniformly by an oscillator to obtain a sensing layer solution.

[0127] S902, coating the sensing layer solution on the electrode surface to form the glucose sensing layer.

[0128] Specifically, 3 uL of the sensing layer solution was dropped onto a 3 mm thick clean glassy carbon electrode surface 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.

[0129] 2. Redox peak potential test of the sensing layer of glucose electrochemical sensor

[0130] The sensing layers A1 to A5 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.

[0131] Figure 1 is a cyclic voltammogram corresponding to the redox complexes prepared in Examples 4-8 provided in the Examples of this application. As can be seen from Figure 1, the potentials of all the redox complexes prepared in Examples 4-8 are less than 10mV. In this way, electrochemical catalytic oxidation of glucose can be achieved at a lower potential, avoiding the simultaneous occurrence of other biological reactions in the human body and the glucose oxidation process under high potential conditions, which would interfere with the results of blood glucose monitoring, thereby improving the selectivity and accuracy of blood glucose monitoring.

[0132] Example 10

[0133] The present embodiment takes a glucose electrochemical sensor electrode as an example to further illustrate a method for preparing a glucose electrochemical sensor electrode.

[0134] 1. Preparation of Glucose Electrochemical Sensing Electrode

[0135] The present invention also provides a method for preparing a glucose electrochemical sensor electrode, comprising the following steps:

[0136] S100, spraying, dripping or dipping the sensing layer prepared in Example 9 onto the surface of the carbon electrode;

[0137] S102, spraying or dipping the outer film layer onto the surface of the carbon electrode containing the sensing layer; preparing the glucose electrochemical sensing electrode.

[0138] Specifically, the sensing layer solution prepared in Example 9 was drop-coated, sprayed, or dip-coated onto the surface of a carbon-printed electrode. As the solvent evaporated, the various compounds cross-linked, gradually forming a film layer. After drying at room temperature for 48 hours, an outer film polymer layer was applied to the electrode surface by dip-coating and then dried at room temperature for another 48 hours to obtain a glucose sensing electrode.

[0139] The glucose sensor electrode has a low oxidation peak operating potential, long-term sensitivity stability, and good safety performance. This is because the redox complex proposed in the examples of this application can react with the polymer resin through its structural active groups, allowing it to be fixed to the polymer backbone through chemical bonds. This prevents the redox complex from migrating and diffusing into human tissue fluid, further improving the service life and safety of the sensor electrode. In another embodiment of the present application, the sensor electrode can be a glucose electrochemical sensor electrode, a uric acid electrochemical sensor electrode, a blood ketone body electrochemical sensor electrode, or a lactate electrochemical sensor electrode.

[0140] 2. Sensing electrode linearity test

[0141] The sensing electrode was immersed in a standard PBS buffer (pH 7.4, 150mM NaCl), followed by an initial pulse of 1.1 volts for 360s. The sensor was maintained at 0.6V for the remainder of the measurement. After waiting for 10 minutes, the sensor reached a constant background, and glucose at concentrations of 5.0, 10.0, 15.0, 20.0, 25.0, 30.0, and 40.0mM was 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 an embodiment of the present application; as can be seen from Figure 2, the sensor has very good linearity between concentrations of 5-40mM. In other words, all the electrons generated during the oxidation of glucose are quickly transferred to the electrode, which improves the transfer efficiency of the electrons generated during the oxidation of glucose, thereby improving the sensitivity of blood glucose monitoring.

[0142] 3. Sensing electrode stability test

[0143] The sensing electrode was immersed in a 3 mM standard glucose solution to test its stability. FIG3 is a graph showing the relationship between the test time and the current intensity provided in the present application 4. As can be seen from FIG3 , the average signal attenuation of the sensor per 24 hours over 6 days was only 0.5%, indicating that the sensor membrane prepared using the present application has good stability.

[0144] In some embodiments, in Formula I: In the redox complex shown:

[0145] R can be C 1-4 The alkane chain may also be one of ethylene, 1,3-propylene, 1,2-propylene, and 1,4-butylene.

[0146] X can be hydroxyl, amino, vinyl, alkynyl, azide, cyano, carboxyl, hydroxymethyl, mercapto, isocyanate, -R a OH or -OCOR b , where R a is an independent methylene or ethylene group, R b C 1-3 In some embodiments, R b It can also be -CH=CH2 or -CH=CHCH3.

[0147] R 1 、R 2 、R 3 and R 4 is a single hydrogen or alkyl group, M is a transition metal, n is the number of positive ions, and A is a counter ion.

[0148] The structural formula of L2 is shown in Formula II:

[0149] Among them, R 5 C 1-4 Alkane chain or o-disubstituted benzene ring; R 10 is H, -CH3 or -CH2CH3; R 6 、R 7 、R 8 and R 9 is independently hydrogen or alkyl.

[0150] In some embodiments, in Formula III: In the redox complex shown:

[0151] m is 2, 3 or 4, and n is 2, 3, 4 or an ortho-disubstituted benzene ring.

[0152] X can be hydroxyl, amino, vinyl, alkynyl, azide, cyano, carboxyl, hydroxymethyl, mercapto, isocyanate, -R a OH or -OCORb Among them, R a is an independent methylene or ethylene group, R b It can be -CH=CH2, -CH=CHCH3 or -CH2CH2COOH.

[0153] R 10 It is H, -CH3 or -CH2CH3.

[0154] In some embodiments, the backbone polymer may include one or more of poly(glycidyl methacrylate), poly(glycidyl acrylate), poly-(ethylene glycol-co-glycidyl acrylate), poly-(hydroxyethyl acrylate-co-glycidyl acrylate), poly-(hydroxyethyl methacrylate-co-glycidyl acrylate), poly-(hydroxyethyl acrylate-co-glycidyl methacrylate), and poly-(hydroxyethyl methacrylate-co-glycidyl methacrylate).

[0155] The above description is only for understanding the method and core idea of ​​the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the scope of protection of the rights of the present application.

Claims

1. A redox complex, wherein: The structural formula of the redox complex is shown in Formula I: In Formula I, R is C 1-4 Alkane chain; X is hydroxyl, amino, vinyl, alkynyl, azide, cyano, carboxyl, hydroxymethyl, mercapto, isocyanate, -R a OH or -OCOR b ;and R a is an independent methylene group or ethylene group; R b C 1-3 alkyl; R 1 , R 2 , R 3 and R 4 is an independent hydrogen or alkyl group; 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 C 1-4 Alkane chain or o-disubstituted benzene ring; R 10 is H, -CH3 or -CH2CH3; R 6 , R 7 , R 8 and R 9 is independently hydrogen or alkyl.

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

3. The redox complex according to claim 1, wherein The counter ion is chloride or hexafluorophosphate.

4. The redox complex according to any one of claims 1 to 3, characterized in that The R is one of ethylene, 1,3-propylene, 1,2-propylene, and 1,4-butylene.

5. The redox complex according to any one of claims 1 to 3, characterized in that The R 1 , R 2 , R 3 and R 4 is independently hydrogen or methyl.

6. The redox complex according to any one of claims 1 to 3, characterized in that The R 6 , R 7 , R 8 and R 9 is independently hydrogen or methyl.

7. The redox complex according to any one of claims 1 to 3, characterized in that The R b It is -CH=CH2 or -CH=CHCH3.

8. The redox complex according to any one of claims 1 to 3, characterized in that The redox complex is a compound represented by formula III: in, m is 2, 3 or 4; n is 2, 3, 4 or o-disubstituted benzene ring; X is hydroxyl, amino, vinyl, alkynyl, azide, cyano, carboxyl, hydroxymethyl, mercapto, isocyanate, -R a OH or -OCOR b ;and R a is an independent methylene group or ethylene group; R b is -CH=CH2, -CH=CHCH3 or -CH2CH2COOH; R 10 It is H, -CH3 or -CH2CH3.

9. The redox complex according to any one of claims 1 to 3, characterized in that The redox complex is a compound represented by formula (1) to (21):

10. A method for preparing a sensing layer solution, characterized in that: The following steps are involved: The redox complex according to any one of claims 1 to 9, the oxidase and the backbone polymer are dissolved in a HEPES buffer solution to obtain a sensing layer solution.

11. The backbone polymer according to claim 10, characterized in that The backbone polymer includes one or more of poly(methacrylate glycidyl ether), poly(acrylate glycidyl ether), poly(ethylene glycol-co-acrylate glycidyl ether), poly(hydroxyethyl acrylate-co-acrylate glycidyl ether), poly(hydroxyethyl methacrylate-co-acrylate glycidyl ether), poly(hydroxyethyl acrylate-co-methacrylate glycidyl ether), and poly(hydroxyethyl methacrylate-co-methacrylate glycidyl ether).

12. A method for preparing a sensing electrode, characterized in that: The following steps are involved: Spraying, dripping or dipping the sensing layer solution prepared according to claim 10 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.

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