Preparation method of ni(ii)-mof and application thereof in electrochemical glucose sensing

Abstract

The application discloses a kind of Ni (II) based metal organic framework Ni (II)-MOF material and application in electrochemical glucose sensing.The application is applied in electrochemical glucose sensing field by synthesizing a case of Ni (II)-MOF by hydrothermal method.The application uses benzene-1,2,3,4,5,6-hexacarboxylic acid (H6L) as organic ligand, introduces 1,4-bis (1-imidazole) benzene (bib), and constructs with periodic three-dimensional framework structure.The Ni (II)-MOF material synthesis process is simple, crystallinity is strong, product purity and yield are high, and structure is novel.The obtained Ni (II)-MOF has ultrafast response time, lower detection limit and higher sensitivity, and has good application prospect in electrochemical glucose sensing.

Description

Technical Field

[0001] This invention pertains to the preparation and electrochemical sensing applications of metal-organic frameworks (MOFs), specifically a Ni(II)-MOF formed with benzene-1,2,3,4,5,6-hexacarboxylic acid as the main ligand, nitrogen-containing ligands introduced, and nickel as the metal center. The electrode material prepared exhibits ultrafast response and ultralow detection limit in electrochemical glucose sensing. Background Technology

[0002] The International Diabetes Federation predicts that the number of people with diabetes worldwide will reach 500 million, but current medical technology still struggles to cure it. Therefore, monitoring blood glucose concentration using rapid and high-precision electrochemical sensing technology is crucial for diabetes prevention. Electrochemical sensing originates from changes in detectable electrical signals caused by the interaction between electrodes and specific analytes. Its efficient operation relies on two systems: 1. Recognition system: Modifying the electrode surface with enzymes, inorganic materials, etc., alters the performance of the electrochemical sensor to identify the target analyte. 2. Signal conversion system: Converting the analyte signal into an electrical signal. Therefore, electrochemical sensors can convert variables that are difficult to measure directly into calculable quantities, thereby achieving qualitative or quantitative detection of the analyte. Electrochemical sensors have advantages such as fast response speed, high efficiency, simple operation, and analyte specificity. Electrochemical glucose sensors include both enzyme sensors and non-enzyme sensors. While enzyme-based electrochemical sensors offer advantages such as rapid detection, they also suffer from high costs and inherent drawbacks: 1. The extraction process for enzyme sensors is complex and lacks controllability; 2. Most enzymes are proteins, and their higher-order structures are prone to collapse and inactivation in acidic, alkaline, or high-temperature environments. Compared to enzyme-based glucose sensors, non-enzyme glucose sensors offer the following advantages: 1. They avoid complex enzyme immobilization techniques. 2. They can efficiently transfer electrons. 3. They are less prone to inactivation. 4. They exhibit good long-term storage stability. Non-enzyme electrochemical glucose sensors can utilize the highly efficient catalytic capabilities of electrode surface active materials to directly electrocatalytically oxidize glucose, achieving blood glucose concentration detection. Therefore, in recent years, developing new electrode materials and constructing efficient, inexpensive, sensitive, and stable non-enzyme glucose sensors has become a research hotspot.

[0003] MOFs (Metal-Organic Facility-Containing Materials) are a class of crystalline porous materials with periodically extended structures. They are formed by the self-assembly of metal nodes (metal ions or metal clusters) with organic ligands through coordination bonds. Furthermore, the unique coordination structures that can be formed between ligands increase the selectivity of MOFs. Their unique structure and open active sites, especially the ultra-high porosity and large specific surface area, are beneficial for the efficient transport of analytes, providing a promising prospect for electrochemical glucose sensors. Benzene-1,2,3,4,5,6-hexacarboxylic acid (H6L) ligands possess six carboxylic acid groups (-COOH), which can be partially or completely deprotonated to form ionic -COO groups. - This characteristic allows H6L to bind with a variety of ligands to construct MOFs with different structures. Therefore, H6L can bind to monodentate, chelate, or bridging ligands as well as metal centers, inducing conformational transformations in structurally diverse MOFs, which enhances the potential of H6L in constructing electrochemical glucose sensors. Summary of the Invention

[0004] This invention synthesizes a metal-organic framework material with benzene-1,2,3,4,5,6-hexacarboxylic acid as the main ligand, 1,4-bis(1-imidazolyl)benzene (bib) as the auxiliary ligand, and nickel as the metal center. This material can be used for non-enzymatic electrochemical glucose sensing, exhibiting ultrafast response and ultra-low detection limit.

[0005] This MOF material was prepared as light blue bulk crystals by hydrothermal conditions using two organic ligands and a nickel salt. Its chemical formula is C0. 12 H 12 N2NiO9 (CTGU-34), molecular formula: {Ni(bib)} 1 / 2 (H2L) 1 / 2 (H2O)3} n H2L 4- It is the anion of benzene-1,2,3,4,5,6-hexacarboxylic acid after the removal of four protons, and bib is 1,4-bis(1-imidazolyl)benzene.

[0006] From the perspective of crystal structure, CTGU-34 belongs to the orthorhombic crystal system with space group Ibam. The cell parameters of CTGU-34 are: V = 6041.0(2) Å. 3 , a = 11.3848(2) Å, b = 15.2582(3) Å, c = 34.7758(7)Å, α = 90°, β = 90°, γ = 90°.

[0007] X-ray single-crystal diffraction experiments show that the asymmetric unit cell of CTGU-34 consists of a Ni 2+Half of the cyclohexane 1,4-dicarboxylic acid-2,3,5,6-tetracarboxylic acid anion (H2L) 4- The asymmetric unit consists of a ligand, half of which is a bib ligand, and three coordinated water molecules. 2+ Two coordination modes are used: (1) Ni 2+ With two H2L 4- The two O atoms and four water molecules on the carboxylic acid group are six-coordinated; (2) Ni 2+ With the two N atoms and two H2L atoms on the two bib ligands 4- The two O atoms on the carboxylic acid group are hexacoordinated with two water molecules. Two such Ni atoms... 2+ It is bound by a carboxylic acid group with an η-O binding mode and Ni-Ocoo - Ligand interactions bridge each other, forming a two-dimensional layer. Adjacent layers are interconnected, forming a two-layer interpenetrating structure through bib ligands. Topologically speaking, the [Ni2(H2L)2N2] unit and each H2L 4- Each of these can be considered as a 4-connected node with bib as the connecting element. Therefore, CTGU-34 can be simplified into a (4,4) connected 3D network.

[0008] The method for synthesizing the CTGU-34 material described above in this invention mainly includes the following steps: Preparation of CTGU-34: Organic ligands H6L, bib and nickel salt were added to a high-pressure autoclave lined with polytetrafluoroethylene and dissolved in a mixed solvent of deionized water and sodium hydroxide solution. After hydrothermal reaction, blue-green blocky crystals were obtained.

[0009] In the above-mentioned CTGU-34 material synthesis scheme, the molar ratio of the organic ligands benzene-1,2,3,4,5,6-hexacarboxylic acid (H6L) and 1,4-bis(1-imidazolyl)benzene (bib) to nickel salts (nickel nitrate hexahydrate, nickel perchlorate hexahydrate, nickel sulfate hexahydrate, nickel acetate tetrahydrate, nickel chloride, nickel oxalate, nickel phosphate, and nickel sulfite) is 2:(1~10):(4~10); the volume ratio of deionized water to sodium hydroxide solution is 20:(1~20). The hydrothermal reaction temperature is 70 ℃~150 ℃, and the reaction time is 12 h~120 h.

[0010] After the reaction was complete, the obtained CTGU-34 crystalline material was naturally cooled to room temperature and then washed three times with deionized water and anhydrous ethanol. The washed powder was activated with anhydrous methanol and dried under vacuum at 80 °C for 12 hours to obtain light green blocky crystals.

[0011] The synthesized CTGU-34 crystal material was ground in an agate mortar and pestle and added to a mixed solvent of water, naphthol, and ethanol. The dispersion was ultrasonically treated for 30 minutes to ensure uniform dispersion, then dropped onto a polished GCE surface and dried at room temperature to obtain the working electrode.

[0012] The room temperature mentioned in this invention refers to the ambient temperature under normal pressure.

[0013] This invention synthesizes a novel metalloenzyme (MOF) material using benzene-1,2,3,4,5,6-hexacarboxylic acid as the main ligand and introducing a nitrogen-containing bridging ligand, 1,4-bis(1-imidazolyl)benzene (bib), as an auxiliary ligand under hydrothermal conditions with nickel salts. The MOF exhibits optimized structure and improved framework stability through π-π and supramolecular interactions between the ligands. Electrochemical glucose sensing tests were conducted on this MOF, which demonstrated an ultrafast response of 0.4 s⁻¹ at room temperature, while achieving a low detection limit of 0.12 µM (S / N=3) and a detection limit of 1704.9 μA mM. -1 cm -2 High sensitivity. Attached Figure Description

[0014] Figure 1 This is a coordination environment diagram of the CTGU-34 crystal structure in this invention.

[0015] Figure 2 This is a three-dimensional packing diagram of the CTGU-34 crystal structure in this invention.

[0016] Figure 3 This is a scanning electron microscope image of the CTGU-34 crystalline material in this invention.

[0017] Figure 4 The images show powder diffraction patterns of freshly synthesized samples and samples soaked in 0.1 M NaOH solution, simulated using CTGU-34 single-crystal data in this invention.

[0018] Figure 5 The image shows the CV curve of the electrochemical sensing response of CTGU-34 to glucose in this invention.

[0019] Figure 6 This refers to the amperometric reaction of CTGU-34 at different potentials (0.60-0.70V) in this invention.

[0020] Figure 7 This refers to the amperometric reaction of CTGU-34 in this invention with continuously added glucose at 0.65 V.

[0021] Figure 8 This is the linear calibration curve of the CTGU-34 in this invention for the amperometric response to continuously added glucose at 0.65 V.

[0022] Figure 9 This is the response time curve of CTGU-34 in this invention to the amperometric reaction with added glucose at 0.65 V.

[0023] Figure 10 The present invention uses CTGU-34 to measure the glucose response in fetal bovine serum samples. Detailed Implementation

[0024] The present invention will be further described below with reference to the embodiments, but the present invention is not limited to the following embodiments.

[0025] 20 mg of H6L, 10 mg of bib organic ligand, and 60 mg of Ni(NO3)2·6H2O were weighed and dissolved in a mixed solvent of 10 mL of deionized water and 0.5 mL of 1M NaOH solution. After sonication to obtain a homogeneous solution, the solution was transferred to a high-pressure reactor lined with polytetrafluoroethylene and reacted at 140 °C for 24 h to obtain CTGU-34 crystalline material.

[0026] Single-crystal samples of CTGU-34 crystalline material were subjected to diffraction data collection at 293 K using a single-crystal diffractometer. The crystal structure was then refined using the Olex2 structural analysis software. The specific structure is shown in Figure 4 of the instruction manual. The purity of the overall prepared samples was confirmed by X-ray powder diffraction.

[0027] The coordination environment diagram, 3D packing diagram, and scanning electron microscope image of the CTGU-34 crystal structure are shown below. Figure 1 , Figure 2 , Figure 3 .

[0028] The powder was allowed to cool naturally to room temperature, and then washed three times with deionized water and anhydrous ethanol. The washed powder was activated with anhydrous methanol for 2 days and dried under vacuum at 60 °C for 12 hours to obtain light green blocky crystals with a yield of 73% (based on H6L).

[0029] To verify the superior effects of this invention, the following analysis and testing were conducted: Weigh 4 mg of the dried metal-organic framework material into a 2 mL sample tube, add 0.2 mL of naphthol, 0.5 mL of anhydrous ethanol, and 1.3 mL of deionized water, and sonicate for 30 min to disperse it evenly. Then, use a pipette to drop the quantitative dispersion onto a glassy carbon electrode. Test the material's response to glucose in 0.1 M NaOH solution. After cyclic voltammetry until stable, add 0.4 mM glucose and scan the CV curve. Figure 5Curve a shows the current response of CTGU-34 after the addition of 1M glucose, with an oxidation peak current of 142.4 µA. Curve b shows the current response of CTGU-34 in 0.1M NaOH solution, with an oxidation peak current of 54.36 µA. Figure 5 As can be seen, after the addition of glucose, CTGU-34 showed a significant increase in oxidation peak current, indicating that CTGU-34 has a good current response to glucose.

[0030] The optimal operating potential of the prepared CTGU-34 electrode material was determined to be 0.65 V by continuously adding 0.4 mM glucose every 100 seconds. Figure 6 .from Figure 6 It can be seen that when the working voltage is 0.65V, the current density of CTGU-34 increases the most with the increase of glucose concentration, indicating that the working voltage of 0.65V is the optimal potential for CTGU-34 to respond to glucose.

[0031] The it curve of continuously added glucose concentration under optimal operating voltage and constant stirring was used to prepare the CTGU-34 electrode material. This was achieved through a clear current response and subsequent steady-state current density, as shown in the graph. Figure 7 .from Figure 7 It can be seen that when glucose is added continuously: 1. Low concentration glucose is added from 50 s to 500 s. 2. High concentration glucose is added from 550 s to 900 s. CTGU-34 shows good and regular current response to glucose at both low and high concentrations.

[0032] The CTGU-34 electrode material exhibits an ideal linear relationship within the glucose concentration range of 0.01-1.0 mM, such as... Figure 8 The linear regression equation is: j(mA cm -2 )=1.7049 [glucose] (mM) + 0.1355 (R 2 =0.9993) from Figure 8 It can be seen that CTGU-34 exhibits a good linear relationship with current density when both low and high concentrations of glucose are added.

[0033] from Figure 9As can be seen from the data, under the optimal voltage, point c represents the time when no glucose was added (199.3 s), and point d represents the time when 0.4 mM glucose was added (199.7 s). Therefore, for the instantaneous response of the electrode material to glucose when 0.4 mM glucose is added, CTGU-34 achieves an ultrafast response of 0.4 seconds.

[0034] When glucose concentrations of 5 mM, 6 mM, and 7 mM were added to fetal bovine serum, the CTGU-34 electrode material exhibited high recovery rates with relative standard deviations (RSDs) within 3%, indicating that CTGU-34 offers significant application potential for the quantitative analysis of glucose levels in vivo. Figure 10 .from Figure 10 As can be seen from the data in groups 1, 2, and 3, the gray bars represent the glucose concentrations added during the detection process, which are 5 mM, 6 mM, and 7 mM, respectively. The black bars represent the glucose concentrations that CTGU-34 can detect after adding 5 mM, 6 mM, and 7 mM glucose concentrations when used as a glucose sensor. In groups 1, 2, and 3, the glucose concentrations that CTGU-34 can detect are 4.61 mM, 5.68 mM, and 6.66 mM, respectively. The reproducibility is above 92% for all groups, indicating that CTGU-34 provides a good and feasible method for the quantitative analysis of glucose levels in organisms.

[0035] 10 mg of H6L, 5 mg of bib organic ligand, and 50 mg of Ni(CH3COO)2·6H2O were weighed and dissolved in a mixed solvent of 20 mL of deionized water and 1 mL of 1M NaOH solution. After sonication to obtain a homogeneous solution, the solution was transferred to a high-pressure reactor lined with polytetrafluoroethylene and reacted at 140 °C for 24 h to obtain the crystalline material. The yield was 21% (based on H6L).

[0036] The performance test is the same as in Example 1.

[0037] 20 mg of H6L, 10 mg of bib organic ligand, and 60 mg of Ni(SO4)2·6H2O were weighed and dissolved in a mixed solvent of 10 mL of deionized water and 0.5 mL of 1M NaOH solution. After sonication to obtain a homogeneous solution, the solution was transferred to a high-pressure reactor lined with polytetrafluoroethylene and reacted at 70 °C for 120 h to obtain crystalline material with a yield of 33% (based on H6L).

[0038] The performance test is the same as in Example 1.

[0039] 10 mg of H6L, 5 mg of bib organic ligand, and 60 mg of Ni(NO3)2·6H2O were weighed and dissolved in a mixed solvent of 10 mL of deionized water and 0.5 mL of 1M NaOH solution. After sonication to obtain a homogeneous solution, the solution was transferred to a high-pressure reactor lined with polytetrafluoroethylene and reacted at 70 °C for 24 h to obtain crystalline material with a yield of 17% (based on H6L).

[0040] The performance test is the same as in Example 1.

[0041] Weigh 20 mg H6L, 10 mg bib organic ligand, and 60 mg NiCl2, and dissolve them in a mixed solvent of 20 mL deionized water and 1 mL 1M NaOH solution. After sonication to obtain a homogeneous solution, transfer it to a high-pressure reactor lined with polytetrafluoroethylene and react at 140 °C for 100 h to obtain crystalline material with a yield of 48% (based on H6L).

[0042] The performance test is the same as in Example 1.

[0043] 10 mg of H6L, 5 mg of bib organic ligand, and 50 mg of Ni(CH3COO)2·6H2O were weighed and dissolved in a mixed solvent of 12 mL of deionized water and 1.5 mL of 1M NaOH solution. After sonication to obtain a homogeneous solution, the solution was transferred to a high-pressure reactor lined with polytetrafluoroethylene and reacted at 120 °C for 48 h to obtain crystalline material with a yield of 37% (based on H6L).

[0044] The performance test is the same as in Example 1.

[0045] 20 mg of H6L, 30 mg of bib organic ligand, and 60 mg of Ni(CH3COO)2·6H2O were weighed and dissolved in a mixed solvent of 15 mL of deionized water and 0.75 mL of 1M NaOH solution. After sonication to obtain a homogeneous solution, the solution was transferred to a high-pressure reactor lined with polytetrafluoroethylene and reacted at 150 °C for 12 h to obtain crystalline material with a yield of 29% (based on H6L).

[0046] The performance test is the same as in Example 1.

[0047] The above description is merely a preferred embodiment of the present invention, but the present invention should not be limited to the content disclosed in this embodiment. Therefore, any equivalent or modified versions made without departing from the spirit of the present invention fall within the scope of protection of the present invention.

Claims

1. A Ni(II)-MOF metal-organic framework material, characterized in that, A crystalline material with the chemical formula C was prepared by hydrothermal treatment with two organic ligands and a nickel salt. 12 H 12 N2NiO9, named CTGU-34; molecular formula: {Ni(bib)} 1 / 2 (H2L) 1 / 2 (H2O)3} n H2L 4- The bib is the anion of benzene-1,2,3,4,5,6-hexacarboxylic acid after the removal of four protons, and is 1,4-bis(1-imidazolyl)benzene. The unit cell parameter of the crystal material is: V = 6041.0(2) Å. 3 , a = 11.3848(2) Å, b = 15.2582(3) Å, c = 34.7758(7) Å, α = 90°, β = 90°, γ = 90°.

2. The Ni(II)-MOF metal-organic framework based on Ni(II) according to claim 1, characterized in that, Ni in asymmetric units 2+ Two coordination modes are used: (1) Ni 2+ With two H2L 4- The two O atoms and four water molecules on the carboxylic acid group are six-coordinated; (2) Ni 2+ With the two N atoms and two H2L atoms on the two bib ligands 4- The two O atoms on the carboxylic acid group are six-coordinated with two water molecules.

3. The Ni(II)-MOF metal-organic framework based on Ni(II) according to claim 1, characterized in that, The nickel salt is any one of nickel nitrate hexahydrate, nickel perchlorate hexahydrate, nickel sulfate hexahydrate, nickel acetate tetrahydrate, nickel chloride, nickel oxalate, nickel phosphate, and nickel sulfite.

4. A method for preparing the Ni(II)-MOF metal-organic framework material according to any one of claims 1-3, characterized in that, Includes the following steps: Preparation of CTGU-34: Organic ligands H6L, bib and Ni(NO3)2·6H2O were added to a high-pressure reactor lined with polytetrafluoroethylene. H6L is benzene-1,2,3,4,5,6-hexacarboxylic acid, dissolved in a mixed solvent of deionized water and sodium hydroxide solution, and subjected to hydrothermal reaction. After the reaction was completed, the mixture was washed.

5. The method according to claim 4, characterized in that, In the preparation of CTGU-34, the hydrothermal reaction temperature is 70-150℃ and the hydrothermal reaction time is 12-120 h.

6. The method according to claim 5, characterized in that, In the preparation of CTGU-34, the hydrothermal reaction temperature was 80 ℃ and the hydrothermal reaction time was 72 hours.

7. The method according to claim 4, characterized in that, In the CTGU-34 material preparation scheme, the molar ratio of the organic ligands benzene-1,2,3,4,5,6-hexacarboxylic acid H6L, 1,4-bis(1-imidazolyl)benzenebib, and nickel nitrate Ni(NO3)2·6H2O is 2:(0.5~10):(4~10); the volume ratio of deionized water and sodium hydroxide solution is 40:1-1:

1.

8. The method according to claim 7, characterized in that, In the CTGU-34 material preparation scheme, the molar ratio of the organic ligands benzene-1,2,3,4,5,6-hexacarboxylic acid H6L, 1,4-bis(1-imidazolyl)benzenebib to nickel nitrate Ni(NO3)2·6H2O is 2:1:6; the volume ratio of deionized water to sodium hydroxide solution is 20:

1.

9. The application of the Ni(II)-based metal-organic framework Ni(II)-MOF material as described in any one of claims 1-3 as a sensing material for electrochemical glucose sensing.

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