Neurotransmitter electrochemical sensor based on high-temperature reduced platinum particles

Abstract

The invention provides a neurotransmitter electrochemical sensor based on high-temperature reduced platinum particles, and belongs to the technical field of sensors. The sensor is characterized in that high-temperature reduced platinum particles are dispersed in a solvent, the high-temperature reduced platinum particles are dripped on a glassy carbon electrode to serve as a working electrode, and the high-temperature reduced platinum particles are obtained by soaking ZIF-8 powder in a chloroplatinic acid solution and performing high-temperature treatment on an obtained product. In the high-temperature heating process, metal reduction and carbonization of the conductive substrate are carried out at the same time, and the conductivity and structural stability of the material are effectively enhanced. And meanwhile, the original MOF structure is reserved to the maximum extent, and the preparation effect of the metal particles is ensured. Through the structure, the metal particles can be uniformly dispersed, the number of active sites of the material is ensured, the electrochemical active area is increased, and the reaction current is increased, so that high-sensitivity detection of neurochemical substances (such as dopamine and ascorbic acid) is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of sensors, and in particular relates to a neurotransmitter electrochemical sensor based on high-temperature reduced platinum particles. Background Art

[0002] Neurotransmitters play a key role in nervous system activities, and accurate detection of their concentration is of great significance for the diagnosis, treatment, and pathogenesis of neurological diseases. However, current neurotransmitter sensor technology still has significant deficiencies in sensitivity and response speed, making it difficult to meet the needs of high-precision, real-time detection. These limitations have hindered its widespread promotion in practical applications.

[0003] Metal-organic frameworks (MOFs) are widely used in the detection of neurotransmitters due to their high specific surface area, adjustable structure, and diverse types (Jacs, 2023, 145(4): 2118-2126; Jacs, 2023, 145(43): 23727-23738), but they still face problems such as poor catalytic activity and poor stability. Summary of the invention

[0004] The purpose of the present invention is to provide a neurotransmitter electrochemical sensor based on high-temperature reduced platinum particles, which is used for high-sensitivity detection of neurochemical substances and has excellent detection performance.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] The present invention provides a neurotransmitter electrochemical sensor based on high-temperature reduced platinum particles. The sensor is prepared by dispersing high-temperature reduced platinum particles in a solvent and drop-casting the particles on a glassy carbon electrode as a working electrode. The high-temperature reduced platinum particles are obtained by immersing ZIF-8 powder in a chloroplatinic acid solution and subjecting the obtained product to high-temperature treatment.

[0007] Preferably, the sensor uses a silver-silver chloride electrode as a reference electrode and a platinum electrode as a counter electrode.

[0008] Preferably, the method for preparing high temperature reduced platinum particles comprises:

[0009] Step 1: Preparation of ZIF-8 powder;

[0010] Step 2: soaking ZIF-8 powder in chloroplatinic acid solution to obtain the product;

[0011] Step 3: Place the product of step 2 into a heating device, rapidly heat it up, then cool it down, and obtain high-temperature reduced platinum particles through post-processing.

[0012] Preferably, the concentration of the chloroplatinic acid solution is 5wt%-20wt%.

[0013] Preferably, the mass g of the ZIF-8 powder: the volume mL of the chloroplatinic acid solution is 1: (3-5).

[0014] Preferably, the soaking time is 6-12 hours.

[0015] Preferably, the setting parameters of the heating equipment in step three are: setting the heating time to 1-5s, the cooling time to 1-3s, and the heating temperature to 1500-2000°C.

[0016] Preferably, the method for preparing the ZIF-8 powder comprises: dissolving zinc salt and 2-methylimidazole in a solvent respectively, then mixing, stirring and standing, and obtaining the ZIF-8 powder after centrifugation, drying and grinding.

[0017] Preferably, the molar ratio of the zinc salt to 2-methylimidazole is 1:10-20.

[0018] Preferably, the stirring time is 1-3 hours, and the standing time is 12-72 hours.

[0019] Beneficial Effects of the Invention

[0020] The present invention provides a neurotransmitter electrochemical sensor based on high-temperature reduced platinum particles, wherein the high-temperature reduced platinum particles are dispersed in a solvent and drop-casted on a glassy carbon electrode as a working electrode, wherein the high-temperature reduced platinum particles are obtained by immersing ZIF-8 powder in a chloroplatinic acid solution and subjecting the obtained product to high-temperature treatment. Compared with the prior art, the present invention provides a larger specific surface area through a well-developed pore structure of a metal organic framework (MOF), thereby achieving a higher metal particle load. During the high-temperature heating process, metal reduction and carbonization of a conductive substrate are carried out simultaneously, effectively enhancing the conductivity and structural stability of the material. At the same time, the original MOF structure is retained to the maximum extent, ensuring the preparation effect of the metal particles. Through this structure, the metal particles can be evenly dispersed, ensuring the number of active sites of the material, increasing the electrochemically active area, and increasing the reaction current, thereby achieving high-sensitivity detection of neurochemical substances (such as dopamine, ascorbic acid, etc.). BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a scanning electron microscope (SEM) image of the high-temperature original platinum particles prepared in Example 1 of the present invention.

[0022] Figure 2 This is an energy dispersive X-ray spectroscopy (EDS) image of the high-temperature reduced platinum particles prepared in Example 1 of the present invention.

[0023] Figure 3 The SEM image of the high-temperature reduced platinum particles prepared in Example 1 of the present invention and the corresponding element distribution map of C and Pt.

[0024] Figure 4 This is an X-ray diffraction (XRD) image of the high-temperature reduced platinum particles prepared in Example 1 of the present invention.

[0025] Figure 5 The N2 adsorption-desorption isotherm curve and pore size distribution curve of the high temperature reduced platinum particles prepared in Example 1 of the present invention.

[0026] Figure 6 This is the detection performance curve of the electrochemical sensor of Example 5 of the present invention. DETAILED DESCRIPTION

[0027] The present invention provides a neurotransmitter electrochemical sensor based on high-temperature reduced platinum particles. The sensor is a high-temperature reduced platinum particle dispersed in a solvent, wherein the solvent is preferably a mixed solution of anhydrous ethanol and deionized water, wherein the volume ratio of anhydrous ethanol to deionized water is preferably 3:1, and 5wt% naphthol is preferably added to the mixed solution. The solution dispersed in the solvent is drop-casted on a glassy carbon electrode as a working electrode, a silver-silver chloride electrode is used as a reference electrode, a platinum sheet electrode is used as a counter electrode, and an electrochemical workstation is connected to form a three-electrode system, and the liquid to be measured (neuroactive substance solution) is an electrolyte for electrochemical measurement. The neuroactive substance is preferably dopamine or ascorbic acid.

[0028] According to the present invention, the high temperature reduced platinum particles are obtained by soaking ZIF-8 powder in chloroplatinic acid solution and subjecting the obtained product to high temperature treatment. The specific preparation method preferably includes:

[0029] Step 1: Preparation of ZIF-8 powder; specifically preferably comprising: dissolving zinc salt and 2-methylimidazole in a solvent, preferably water, methanol or anhydrous ethanol, then mixing, stirring and standing, the stirring time is preferably 1-3 hours, the standing time is preferably 12-72 hours, more preferably 24 hours, and then centrifuging, drying and grinding to obtain ZIF-8 powder. The molar ratio of zinc salt to 2-methylimidazole is preferably 1:10-20; the zinc salt is preferably zinc acetate or zinc nitrate hexahydrate;

[0030] Step 2: soaking the ZIF-8 powder in a chloroplatinic acid solution, the soaking time is preferably 6-12 hours, and then drying to obtain a product; the concentration of the chloroplatinic acid solution is 5wt%-20wt%, and the present invention limits the concentration of the chloroplatinic acid solution. Too low a concentration of the chloroplatinic acid solution will cause a decrease in the loading rate, and too high a concentration will lead to incomplete reaction; the mass g of the ZIF-8 powder: the volume mL of the chloroplatinic acid solution is preferably 1: (3-5);

[0031] Step 3: Put the product of step 2 into a heating device, heat it up quickly and then cool it down. The parameters of the heating device are preferably: the heating time is preferably 1-5s, more preferably 2s, the cooling time is 1-3s, more preferably 2s, the wave number is 1, and the heating temperature is 1500-2000°C. The temperature in the heating device needs to be strictly controlled in the present invention. When the temperature is too low, the reaction will be incomplete, and when the temperature is too high, the internal structure will be lost. Then the product obtained after high temperature treatment is post-treated to obtain high temperature reduced platinum particles. The present invention has no special restrictions on the heating device used, and it is preferably a Joule heat device conventionally used in the art.

[0032] The post-treatment is preferably to add hydrochloric acid to the above-mentioned material, stir and then let it stand, the standing time is preferably 6 hours, centrifuge to remove the supernatant, wash repeatedly with hydrochloric acid 3-4 times, and then wash repeatedly with anhydrous ethanol 3-4 times, and dry the obtained material in a drying oven to obtain high-temperature reduced platinum particles.

[0033] The high-temperature reduced platinum particles prepared by the invention have abundant specific surface area, increase the attachment sites of platinum, and improve the catalytic activity.

[0034] The present invention is described in detail below with reference to specific examples, and the raw materials involved in the examples are all commercially available.

[0035] Example 1

[0036] (1) Dissolve 1.5 g of zinc acetate in 50 mL of anhydrous ethanol, denoted as A, and then dissolve 5.6 g of 2-methylimidazole in 50 mL of anhydrous ethanol, denoted as B. Mix A and B, stir for 1 hour, and then let stand for 24 hours. After standing, centrifuge 3-4 times. Dry and grind the obtained material in a drying oven at 60°C to obtain ZIF-8 powder.

[0037] (2) The ZIF-8 powder was immersed in 5 ml of 5 wt% chloroplatinic acid solution, left to stand for 6 h, and then dried and ground.

[0038] (3) The above-prepared material is placed in a Joule heating device, evacuated and introduced with protective gas. The parameters are set to 1500°C, heating for 2s, cooling for 2s, and a wave number of 1. The temperature is rapidly raised to 1500°C, and then cooled to room temperature to obtain a crude product.

[0039] (4) Take 20 ml of 1M hydrochloric acid and add it to the above materials. After stirring, let it stand for 6 hours. Centrifuge to remove the supernatant, wash it repeatedly with 1M hydrochloric acid for 3-4 times, and then wash it repeatedly with anhydrous ethanol for 3-4 times. Dry the obtained material in a drying oven at 60°C to obtain high-temperature reduced platinum particles.

[0040] Figure 1 This is a scanning electron microscope (SEM) image of the high-temperature original platinum particles prepared in Example 1 of the present invention. It can be seen from the figure that the high-temperature reduced platinum particle material prepared in the present invention has a relatively large number of pore structures.

[0041] Figure 2 This is an energy dispersive X-ray spectroscopy (EDS) image of the high temperature reduced platinum particles prepared in Example 1 of the present invention. It can be seen from the figure that the high temperature reduced platinum particle material prepared in the present invention mainly contains carbon and platinum.

[0042] Figure 3 The SEM image (a) of the high-temperature reduced platinum particles prepared in Example 1 of the present invention and the corresponding element distribution diagrams of C (b) and Pt (c). It can be seen from the figure that the high-temperature reduced platinum particle material prepared in the present invention mainly uses carbon as a substrate, and the platinum particles are distributed on the carbon, which proves the formation of metallic platinum and its attachment to the carbon.

[0043] Figure 4 This is an X-ray diffraction (XRD) image of the high-temperature reduced platinum particles prepared in Example 1 of the present invention. As can be seen from the figure, the platinum particles in the high-temperature reduced platinum particle material prepared by the present invention are spherical and attached to carbon, proving that the platinum element exists in the form of a single substance.

[0044] Figure 5 The N2 adsorption-desorption isotherm (a) and pore size distribution curve (b) of the high-temperature reduced platinum particles prepared in Example 1 of the present invention. It can be seen from the figure that the high-temperature reduced platinum particle material prepared in the present invention has a large specific surface area and can provide more attachment sites for platinum.

[0045] Example 2

[0046] (1) Dissolve 1.5 g of zinc acetate in 50 mL of anhydrous ethanol, denoted as A, and then dissolve 5.6 g of 2-methylimidazole in 50 mL of anhydrous ethanol, denoted as B. Mix A and B, stir for 1 hour, and then let stand for 24 hours. After standing, centrifuge 3-4 times. Dry and grind the obtained material in a drying oven at 60°C to obtain ZIF-8 powder.

[0047] (2) The ZIF-8 powder was immersed in 5 ml of 5 wt% chloroplatinic acid solution, left to stand for 6 h, and then dried and ground.

[0048] (2) The above-prepared material is placed in a Joule heating device, evacuated and introduced with protective gas. The parameters are set to 2000°C, heating for 2s, cooling for 2s, and a wave number of 1. The temperature is rapidly raised to 2000°C, and then cooled to room temperature to obtain a crude product.

[0049] (4) Take 20 ml of 1M hydrochloric acid and add it to the above materials. After stirring, let it stand for 6 hours. Centrifuge to remove the supernatant, wash it repeatedly with 1M hydrochloric acid for 3-4 times, and then wash it repeatedly with anhydrous ethanol for 3-4 times. Dry the obtained material in a drying oven at 60°C to obtain high-temperature reduced platinum particles.

[0050] Example 3

[0051] (1) Dissolve 1.5 g of zinc acetate in 50 mL of anhydrous ethanol, denoted as A, and then dissolve 5.6 g of 2-methylimidazole in 50 mL of anhydrous ethanol, denoted as B. Mix A and B, stir for 1 hour, and then let stand for 24 hours. After standing, centrifuge 3-4 times. Dry and grind the obtained material in a drying oven at 60°C to obtain ZIF-8 powder.

[0052] (2) The ZIF-8 powder was immersed in 5 ml of 10 wt% chloroplatinic acid solution, left to stand for 6 h, and then dried and ground.

[0053] (2) The above-prepared material is placed in a Joule heating device, evacuated and introduced with protective gas. The parameters are set to 1500°C, heating for 2s, cooling for 2s, and a wave number of 1. The temperature is rapidly raised to 1500°C, and then cooled to room temperature to obtain a crude product.

[0054] (4) Take 20 ml of 1M hydrochloric acid and add it to the above materials. After stirring, let it stand for 6 hours. Centrifuge to remove the supernatant, wash it repeatedly with 1M hydrochloric acid for 3-4 times, and then wash it repeatedly with anhydrous ethanol for 3-4 times. Dry the obtained material in a drying oven at 60°C to obtain high-temperature reduced platinum particles.

[0055] Example 4

[0056] (1) Dissolve 1.5 g of zinc acetate in 50 mL of anhydrous ethanol, denoted as A, and then dissolve 5.6 g of 2-methylimidazole in 50 mL of anhydrous ethanol, denoted as B. Mix A and B, stir for 1 hour, and then let stand for 24 hours. After standing, centrifuge 3-4 times. Dry and grind the obtained material in a drying oven at 60°C to obtain ZIF-8 powder.

[0057] (2) The ZIF-8 powder was immersed in 5 ml of 20 wt% chloroplatinic acid solution, left to stand for 6 h, and then dried and ground.

[0058] (2) The above-prepared material is placed in a Joule heating device, evacuated and introduced with protective gas. The parameters are set to 1500°C, heating for 2s, cooling for 2s, and a wave number of 1. The temperature is rapidly raised to 1500°C, and then cooled to room temperature to obtain a crude product.

[0059] (4) Take 20 ml of 1M hydrochloric acid and add it to the above materials. After stirring, let it stand for 6 hours. Centrifuge to remove the supernatant, wash it repeatedly with 1M hydrochloric acid for 3-4 times, and then wash it repeatedly with anhydrous ethanol for 3-4 times. Dry the obtained material in a drying oven at 60°C to obtain high-temperature reduced platinum particles.

[0060] Example 5

[0061] (1) Dissolve 1.95 g of zinc nitrate hexahydrate in 50 mL of anhydrous ethanol, denoted as A, and then dissolve 2.15 g of 2-methylimidazole in 50 mL of anhydrous ethanol, denoted as B. A and B are mixed, stirred for 1 hour, and then allowed to stand for 24 hours. After standing, centrifuge 3-4 times, and the resulting material is dried and ground in a drying oven at 60° C. to obtain ZIF-8 powder.

[0062] (2) The ZIF-8 powder was immersed in 5 ml of 5 wt% chloroplatinic acid solution, left to stand for 6 h, and then dried and ground.

[0063] (2) The above-prepared material is placed in a Joule heating device, evacuated and introduced with protective gas. The parameters are set to 1500°C, heating for 2s, cooling for 2s, and a wave number of 1. The temperature is rapidly raised to 1500°C, and then cooled to room temperature to obtain a crude product.

[0064] (4) Take 20 ml of 1M hydrochloric acid and add it to the above materials. After stirring, let it stand for 6 hours. Centrifuge to remove the supernatant, wash it repeatedly with 1M hydrochloric acid for 3-4 times, and then wash it repeatedly with anhydrous ethanol for 3-4 times. Dry the obtained material in a drying oven at 60°C to obtain high-temperature reduced platinum particles.

[0065] Example 5 Neurotransmitter electrochemical sensor

[0066] The high-temperature reduced platinum particles prepared in Example 1 were dispersed in a mixed solution of anhydrous ethanol and deionized water (the volume ratio of anhydrous ethanol to deionized water was 3:1, containing 5wt% naphthol), and were drop-cast on a glassy carbon electrode as a working electrode, a silver-silver chloride electrode as a reference electrode, a platinum sheet electrode as a counter electrode, and a dopamine solution as an electrolyte. The voltage range was set to 0.1V-0.3V, the scan rate was 50mV / s, and the cyclic voltammetry (CV) curve was measured; the voltage range was set to -0.3V-0.55V, and the differential pulse voltammetry (DPV) curve was measured.

[0067] Figure 6 is the detection performance curve of the electrochemical sensor of Example 5 of the present invention, wherein: Figure 6 (a) is the cyclic voltammetry (CV) curve in 0.5 M H2SO4 (scan rate: 100 mV / s). Figure 6 (b) is the CV curve in 1 mM dopamine (scan rate: 50 mV / s, artificial cerebrospinal fluid, pH 7.4-7.5). Figure 6 (c) Differential pulse voltammetry (DPV) curves in different concentrations of dopamine (0-100 μM) (artificial cerebrospinal fluid, pH 7.4-7.5). Figure 6 (d) is a calibration curve of dopamine concentration and peak current. As can be seen from the figure, the high-temperature reduced platinum particle material prepared by the present invention can be used as an electrochemical sensor to observe the adsorption and desorption of hydrogen on different crystal faces of metal platinum, and can also quantitatively respond to dopamine.

Claims

1. A neurotransmitter electrochemical sensor based on high temperature reduced platinum particles, characterized in that: The sensor is prepared by dispersing high-temperature reduced platinum particles in a solvent and drop-casting the particles on a glassy carbon electrode as a working electrode. The high-temperature reduced platinum particles are obtained by soaking ZIF-8 powder in a chloroplatinic acid solution and subjecting the obtained product to high-temperature treatment.

2. A neurotransmitter electrochemical sensor based on high temperature reduced platinum particles according to claim 1, characterized in that: The sensor uses a silver-silver chloride electrode as a reference electrode and a platinum sheet electrode as a counter electrode.

3. A neurotransmitter electrochemical sensor based on high temperature reduced platinum particles according to claim 1, characterized in that: The method for preparing high-temperature reduced platinum particles comprises: Step 1: Preparation of ZIF-8 powder; Step 2: soaking ZIF-8 powder in chloroplatinic acid solution to obtain the product; Step 3: Place the product of step 2 into a heating device, rapidly heat it up, then cool it down, and obtain high-temperature reduced platinum particles through post-processing.

4. A neurotransmitter electrochemical sensor based on high temperature reduced platinum particles according to claim 3, characterized in that: The concentration of the chloroplatinic acid solution is 5wt%-20wt%.

5. The neurotransmitter electrochemical sensor based on high temperature reduced platinum particles according to claim 3, characterized in that: The mass g of the ZIF-8 powder: the volume mL of the chloroplatinic acid solution is 1: (3-5).

6. The neurotransmitter electrochemical sensor based on high temperature reduced platinum particles according to claim 3, characterized in that: The soaking time is 6-12 hours.

7. The neurotransmitter electrochemical sensor based on high temperature reduced platinum particles according to claim 3, characterized in that: The setting parameters of the heating equipment in step three are: setting the heating time to 1-5s, the cooling time to 1-3s, and the heating temperature to 1500-2000°C.

8. The neurotransmitter electrochemical sensor based on high temperature reduced platinum particles according to claim 3, characterized in that: The preparation method of the ZIF-8 powder comprises: dissolving zinc salt and 2-methylimidazole in a solvent respectively, then mixing, stirring and standing, and obtaining the ZIF-8 powder after centrifugation, drying and grinding.

9. The neurotransmitter electrochemical sensor based on high temperature reduced platinum particles according to claim 8, characterized in that: The molar ratio of the zinc salt to the 2-methylimidazole is 1:10-20.

10. The neurotransmitter electrochemical sensor based on high temperature reduced platinum particles according to claim 8, characterized in that: The stirring time is 1-3 hours, and the standing time is 12-72 hours.

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