Electrochemical method for high selective detection of hydrogen sulfide in vivo using sodium sulfide pretreated nanosilver carbon fiber microelectrode

Abstract

The application discloses an electrochemical method for high-selectivity detection of hydrogen sulfide in a living body by using a nano-silver carbon fiber microelectrode pretreated by sodium sulfide. The application discloses an electrochemical method for high-selectivity detection of hydrogen sulfide in a brain nervous system. The method comprises the following steps: silver nano-particles are electrodeposited on the surface of a carbon fiber microelectrode by using an electrodeposition method; the electrode is pretreated in a sodium sulfide solution, so that a silver sulfide film is generated on the surface of the electrode, the surface of the microelectrode is regulated, and the purpose of high-selectivity detection of hydrogen sulfide in a living body is achieved. Hydrogen sulfide is combined with silver nano-particles to form silver sulfide which is deposited on the surface of the electrode to cause a change in the potential of the electrode. The change in the potential in the reaction process is monitored in real time by using an open circuit potential method, so that the change in the concentration of hydrogen sulfide can be reflected. Thus, the method can realize high-selectivity detection of hydrogen sulfide in a condition closest to physiological conditions.

Description

Technical Field

[0001] The present invention belongs to the field of analysis, and in particular relates to the preparation of a nano-silver carbon fiber microelectrode pretreated with sodium sulfide and its application in detecting hydrogen sulfide in biological samples such as a living brain nervous system. Background Art

[0002] Hydrogen sulfide is widely present in organisms, participating in a variety of physiological and pathological processes and playing an important role. It is considered an important gaseous signaling molecule. The content of hydrogen sulfide is closely related to the body's homeostasis; abnormal hydrogen sulfide content (increase or decrease) is closely related to cardiovascular disease, endocrine disorders, gastrointestinal diseases, and neurological diseases. Therefore, real-time and accurate monitoring of hydrogen sulfide content in biological samples is of great significance. Common biological samples include cells (single cells, cell clusters), tissues (brain tissue, liver, kidney), living organisms (mice, rats, rabbits), body fluids (serum, blood, urine), and various microorganisms (bacteria, fungi). However, due to the complexity of the test samples, interference from sulfur-containing compounds, and the different forms of hydrogen sulfide under different physiological conditions, accurate detection in biological samples is difficult.

[0003] Silver nanoparticles combine with hydrogen sulfide to form a silver sulfide precipitate, which can induce a potential change to detect hydrogen sulfide. However, when applied to biological samples, this method is susceptible to interference from other sulfur-containing compounds and electroactive substances, necessitating improvements. The present invention improves the selectivity of silver nanoparticle-modified carbon fiber microelectrodes by pretreating the microelectrode surface with sodium sulfide, effectively avoiding interference from other substances and achieving specific detection of hydrogen sulfide. Summary of the Invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0005] The present invention is accomplished based on the following knowledge and findings of the inventors:

[0006] Endogenous hydrogen sulfide in the human body is widely involved in the physiological and pathological processes of the body, such as protecting neurons and glial cells, inducing long-term potentials in the hippocampus, and is also related to Parkinson's disease, ischemic stroke and brain damage. Under physiological conditions (pH = 7.4), different forms of sulfide (S 2- , HS -, H2S, polysulfides, etc.) are easily converted and due to the chemical instability of hydrogen sulfide under physiological conditions, the accurate tracking and monitoring of trace hydrogen sulfide is a difficulty in current research. There are many methods to achieve hydrogen sulfide tracking detection, such as fluorescence, gas chromatography, colorimetry, etc., but these methods generally have problems such as complex procedures, complex preparations, and poor timeliness. Electrochemical detection has the advantages of being fast, sensitive, and able to achieve real-time detection in vivo. Silver nanoparticles combine with sodium sulfide to form silver sulfide precipitates to cause potential changes, which can achieve the purpose of detecting hydrogen sulfide. However, this method is easily interfered by other sulfur-containing compounds and electroactive substances.

[0007] Silver nanoparticle-modified carbon fiber microelectrodes react with hydrogen sulfide, and the combination of the two generates silver sulfide that is deposited on the electrode surface, causing a potential change. Detecting this potential change using the open-circuit potential method can reflect the concentration of hydrogen sulfide. However, when using this method to detect hydrogen sulfide in the body, it is subject to interference from other substances in the human body environment, such as other sulfur-containing compounds and electroactive substances. Therefore, the inventors cleverly designed a method for pretreating silver nanoparticle-modified carbon fiber microelectrodes with sodium sulfide, achieving the purpose of selective detection of hydrogen sulfide in vivo. After pretreatment, sodium sulfide combines with silver nanoparticles to form a silver sulfide film that adheres to the electrode surface. The presence of this film can, on the one hand, hinder other neuroactive substances (represented by ascorbic acid) from reaching the interior of the electrode to react. On the other hand, the binding force of other sulfur-containing compounds (represented by L-cysteine) on the treated surface with silver nanoparticles is much weaker than that of hydrogen sulfide. Based on these two aspects, selective detection of hydrogen sulfide is achieved.

[0008] In a first aspect of the present invention, the present invention provides a method for preparing a carbon fiber microelectrode modified with silver nanoparticles pretreated with sodium sulfide.

[0009] The method for preparing a sodium sulfide pretreated carbon fiber microelectrode provided by the present invention comprises the following steps:

[0010] 1) Silver nanoparticles were modified on the surface of carbon fiber microelectrodes by electrodeposition;

[0011] 2) The carbon fiber microelectrode modified with silver nanoparticles is placed in a sodium sulfide solution for pretreatment to form a silver sulfide film on its surface.

[0012] The silver sulfide film can regulate the surface morphology of the microelectrode, thereby avoiding interference from other substances. Hydrogen sulfide and silver nanoparticles combine to form silver sulfide, which is deposited on the surface of the carbon fiber microelectrode, causing the electrode surface potential to change, thereby achieving the purpose of highly selective detection of hydrogen sulfide in vivo.

[0013] According to an embodiment of the present invention, the electrolyte used in the electrodeposition is a mixed solution containing 1 mmol / L KNO3 and 0.25 mmol / L AgNO3.

[0014] According to an embodiment of the present invention, the electrodeposition is performed using a constant potential deposition method under the condition of a voltage of -0.2 V for 200 s.

[0015] According to an embodiment of the present invention, the electrodeposition is achieved in a two-electrode system or a three-electrode system; wherein, in the two-electrode system, the working electrode is the carbon fiber microelectrode, and the reference electrode is an Ag / AgCl electrode; in the three-electrode system, the working electrode is the carbon fiber microelectrode, the counter electrode is a Pt electrode, and the reference electrode is an Ag / AgCl electrode or a saturated calomel electrode.

[0016] According to an embodiment of the present invention, the concentration of sodium sulfide in the sodium sulfide solution is 5 μM, the pretreatment method is open circuit potential method, and the treatment time is 5 minutes.

[0017] The above-mentioned open circuit potential method can be implemented in a two-electrode system or a three-electrode system. In the two-electrode system, the working electrode is the sodium sulfide pretreated carbon fiber microelectrode, and the reference electrode is an Ag / AgCl electrode. In the three-electrode system, the working electrode is the sodium sulfide pretreated carbon fiber microelectrode, the counter electrode is a Pt electrode, and the reference electrode is an Ag / AgCl electrode or a saturated calomel electrode.

[0018] The carbon fiber microelectrode described in the present invention includes: a glass capillary, wherein both ends of the glass capillary are sealed; a carbon fiber / conductive metal wire composite, wherein the carbon fiber / conductive metal wire composite is arranged in the glass capillary and extends to the outside of the sealed port at one end of the glass capillary, wherein the carbon fiber / conductive metal wire composite is formed by fixing carbon fiber on the conductive metal wire; optionally, the length of the carbon fiber extending from the carbon fiber / conductive metal wire composite to the outside of the sealed port at one end of the glass capillary is 200 to 500 μm; optionally, the conductive metal wire is copper wire, iron wire or silver wire.

[0019] According to an embodiment of the present invention, the carbon fiber microelectrode needs to be electrochemically activated before use, specifically as follows: first apply a +1.5V potential for 80s, then polarize at 0.1V s -1 Cyclic voltammograms were scanned in the potential range of 0.0-1.0 V at a scan rate of 1.50 nm until a stable cyclic voltammogram was obtained.

[0020] According to an embodiment of the present invention, the carbon fiber microelectrode needs to be cleaned as follows before electrochemical activation: the microelectrode is ultrasonicated in acetone, 3.0 mol / L HNO3 and 1.0 mol / L KOH solution for 2 minutes in sequence.

[0021] The carbon fiber microelectrode prepared by the above method also falls within the protection scope of the present invention.

[0022] In a second aspect of the present invention, the present invention provides the use of the sodium sulfide pretreated carbon fiber microelectrode.

[0023] The application of the sodium sulfide pretreated carbon fiber microelectrode provided by the present invention is the application in the following 1) or 2):

[0024] 1) Application in the preparation of products for in vitro and / or in vivo detection of hydrogen sulfide;

[0025] 2) Application in in vitro and / or in vivo detection of hydrogen sulfide.

[0026] Wherein, the living body includes the human body and animals with a central nervous system;

[0027] The in vivo detection of hydrogen sulfide specifically refers to the detection of hydrogen sulfide by open circuit potential method in the living brain;

[0028] The product may be an electrochemical sensor, etc.

[0029] In a third aspect, the present invention provides a method for detecting hydrogen sulfide in a sample.

[0030] The method for detecting hydrogen sulfide in a sample provided by the present invention comprises the following steps:

[0031] The sodium sulfide pretreated carbon fiber microelectrode is inserted into the sample to be tested as a working electrode, and the open circuit potential method is used for detection. According to the obtained electrical signal response value (such as electrode voltage), it is determined whether the sample to be tested contains hydrogen sulfide.

[0032] If the electrical signal response value can be measured, it means that hydrogen sulfide exists in the sample to be tested, otherwise it does not contain hydrogen sulfide.

[0033] The sample to be tested is artificial cerebrospinal fluid containing or not containing hydrogen sulfide, or the central nervous system of a living body (such as cerebrospinal fluid of a living body), wherein the living body includes a human body and an animal with a central nervous system.

[0034] The open circuit potential method can be implemented in a two-electrode system or a three-electrode system; in the two-electrode system, the working electrode is a sodium sulfide pretreated carbon fiber microelectrode, and the reference electrode is an Ag / AgCl electrode; in the three-electrode system, the working electrode is a sodium sulfide pretreated carbon fiber microelectrode, the counter electrode is a Pt electrode, and the reference electrode is an Ag / AgCl electrode or a saturated calomel electrode.

[0035] Furthermore, based on the electrical signal response value of hydrogen sulfide obtained by the above method and the linear relationship between the electrical signal response value and the hydrogen sulfide concentration, the concentration of hydrogen sulfide in the sample to be tested can be calculated.

[0036] The method provided by the present invention can qualitatively detect whether hydrogen sulfide exists in vitro or in vivo, and can also quantitatively detect the concentration of hydrogen sulfide in vitro or in vivo, such as for in situ electrochemical analysis of hydrogen sulfide in the brain, to achieve highly selective detection of hydrogen sulfide.

[0037] In a fourth aspect, the present invention provides a method for quantitatively detecting hydrogen sulfide in a sample.

[0038] The method provided by the present invention for quantitatively detecting hydrogen sulfide in a sample to be tested comprises the following steps:

[0039] 1) Sodium sulfide-pretreated carbon fiber microelectrodes were used as working electrodes and inserted into artificial cerebrospinal fluid containing different concentrations of hydrogen sulfide. The open circuit potential method was used to detect the electrical signal response values ​​corresponding to different concentrations of hydrogen sulfide, and a standard curve of hydrogen sulfide concentration-electrical signal response value was prepared;

[0040] 2) replacing the artificial cerebrospinal fluid containing different concentrations of hydrogen sulfide with the test sample, and measuring using the same method as step 1) to obtain the electrical signal response value of the test sample and substitute it into the standard curve to calculate the concentration of hydrogen sulfide in the test sample.

[0041] Compared with the prior art, the present invention has the following advantages:

[0042] 1) Through a simple pretreatment process, a thin layer of silver sulfide film is formed on the surface of the silver nanoparticle-modified carbon fiber microelectrode. The silver sulfide film effectively blocks electrochemically active substances from reaching the electrode surface for reaction. Furthermore, the binding ability of other sulfur-containing compounds to silver nanoparticles is much lower than that of silver nanoparticles to hydrogen sulfide, enabling highly selective detection of hydrogen sulfide.

[0043] 2) The open circuit potential method was used for detection in the experiment. No voltage was applied to the reaction system, which effectively avoided the generation of oxidative stress response in the body, thereby achieving selective detection of hydrogen sulfide under the most physiological conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 A schematic diagram of the process of electrode preparation and testing provided by the present invention;

[0045] Figure 2 : is the open circuit potential detection curve of the response to the interferent before and after pretreatment obtained in the embodiment;

[0046] Figure 3 This is a characterization diagram of the pretreated nanosilver carbon fiber microelectrode obtained in the embodiment;

[0047] Figure 4The open circuit potential gradient curve and concentration curve for in vitro detection of hydrogen sulfide concentration obtained in the embodiment;

[0048] Figure 5 This is the open circuit potential curve obtained in the example for detecting hydrogen sulfide concentration in vivo using the peritoneal perfusion method. DETAILED DESCRIPTION

[0049] The present invention is further described below with reference to specific examples, but the present invention is not limited to the following examples. The methods described are conventional methods unless otherwise specified. The raw materials described can be obtained from public commercial channels unless otherwise specified.

[0050] In the first aspect of the present invention, a method for pretreating a carbon fiber microelectrode with sodium sulfide is proposed. Before conducting an in vivo analysis, the in vitro performance test of the electrode is performed in advance. Figure 1 , the method comprising:

[0051] S100: Silver nanoparticles deposited on the surface of carbon fiber microelectrodes

[0052] The carbon fiber microelectrode was placed in a mixed electrolyte containing 1 mmol / L KNO3 and 0.25 mmol / L AgNO3, and silver nanoparticles were modified on the surface of the carbon fiber microelectrode by electrodeposition. The electrodeposition used a constant potential deposition method with a condition of -0.2 V and a deposition time of 200 s.

[0053] The electrodeposition can be achieved in a two-electrode system or a three-electrode system. In the two-electrode system, the working electrode is the carbon fiber microelectrode and the reference electrode is an Ag / AgCl electrode. In the three-electrode system, the working electrode is the carbon fiber microelectrode, the counter electrode is a Pt electrode, and the reference electrode is an Ag / AgCl electrode or a saturated calomel electrode.

[0054] S200: Pre-treat the electrode in a solution containing sodium sulfide

[0055] In this step, the silver nanoparticle-modified carbon fiber microelectrode was placed in a solution containing 5 μM sodium sulfide and treated by open circuit potential method for 5 minutes to obtain a sodium sulfide pretreated carbon fiber microelectrode.

[0056] The above-mentioned pretreatment process can be implemented in a two-electrode system or a three-electrode system. In the two-electrode system, the working electrode is the silver nanoparticle-modified carbon fiber microelectrode, and the reference electrode is an Ag / AgCl electrode. In the three-electrode system, the working electrode is the silver nanoparticle-modified carbon fiber microelectrode, the counter electrode is a Pt electrode, and the reference electrode is an Ag / AgCl electrode or a saturated calomel electrode.

[0057] S300: Plotting concentration curves

[0058] The analyte (Na2S) is added to artificial cerebrospinal fluid and tested using open circuit potential. As the concentration of the analyte is gradually increased, a gradient change in the potential curve can be observed. After each addition of the analyte to the artificial cerebrospinal fluid, the corresponding working electrode electrical signal (electrode voltage) is measured using open circuit potential. This provides electrode information that corresponds specifically to the analyte concentration, thereby generating a standard curve.

[0059] The above-mentioned open circuit potential method can be implemented in a two-electrode system or a three-electrode system. In the two-electrode system, the working electrode is the sodium sulfide pretreated carbon fiber microelectrode, and the reference electrode is an Ag / AgCl electrode. In the three-electrode system, the working electrode is the sodium sulfide pretreated carbon fiber microelectrode, the counter electrode is a Pt electrode, and the reference electrode is an Ag / AgCl electrode or a saturated calomel electrode.

[0060] When using the open-circuit potential method, no voltage is applied to the working electrode; instead, the potential difference between the working and reference electrodes is measured directly. Once the background voltage stabilizes, a fixed amount of analyte is added to the artificial cerebrospinal fluid, and the electrode voltage is measured simultaneously to obtain the initial analyte concentration and the corresponding electrode voltage. Subsequently, a fixed amount of analyte is added to the artificial cerebrospinal fluid multiple times, causing a gradient of analyte concentration. The electrode voltage is measured with each change in analyte concentration.

[0061] In a second aspect of the present invention, the present invention proposes the use of the aforementioned electrode for detecting hydrogen sulfide in a living brain.

[0062] Example 1

[0063] Carbon fiber microelectrodes were used as detection electrodes.

[0064] Preparation of the carbon fiber electrode: First, a glass capillary (outer diameter: 1.5 mm; inner diameter: 0.89 mm; length: 10 cm) was drawn into two tapered capillaries with very fine tips using a microelectrode puller (WD-1, Chengdu Instrument Factory). Under a microscope, the tips were gently cut with a glass cutter, leaving the inner diameter of the end at approximately 30-50 μm. A carbon fiber approximately 2 cm long was then bonded to a copper wire using silver conductive adhesive. This was then threaded into the drawn capillary, leaving approximately 200-500 μm of carbon fiber exposed at the capillary tip. Both ends of the capillary were sealed with insulating adhesive to secure the copper wire and capillary together. Under a microscope, the portion of the carbon fiber protruding from the capillary was cut with a knife to 200-500 μm. This completed the carbon fiber microelectrode.

[0065] The prepared microelectrode was ultrasonicated in acetone, 3.0 mol / L HNO3 and 1.0 mol / L KOH solution for 2 min. Then, it was electrochemically activated in 1 mol / L sodium hydroxide solution: first, a potential of +1.5 V was applied for 80 s, then a potential of 0.1 V was applied for 80 s. -1 Cyclic voltammograms were scanned in the potential range of 0.0-1.0 V at a scan rate of 1.50 nm until a stable cyclic voltammogram was obtained.

[0066] Preparation of silver nanoparticle-modified carbon fiber microelectrodes: First, a mixed electrolyte of 1 mmol / L KNO3 and 0.25 mmol / L AgNO3 was prepared. The CFE was placed in a beaker and a three-electrode system was formed with a platinum wire as the counter electrode and an Ag / AgCl electrode as the reference electrode. A constant potential deposition method was used to apply a voltage of -0.2 V to the carbon fiber microelectrode for 200 s to deposit a layer of silver nanoparticles on its surface to obtain silver nanoparticle-modified carbon fiber electrodes (AgNPs-CFEs).

[0067] The above-mentioned electrodeposition can also be achieved in a two-electrode system. In the two-electrode system, the working electrode is a carbon fiber microelectrode electrode and the reference electrode is an Ag / AgCl electrode.

[0068] Sodium sulfide pretreatment of silver nanoparticle modified carbon fiber electrode: AgNPs-CFEs were placed in a solution containing 5μM sodium sulfide (Na2S) and reacted for 5 minutes under open circuit potential method until the potential reached equilibrium and a layer of silver sulfide film was formed on the surface of silver nanocarbon fiber electrode. The silver nanocarbon fiber electrode pretreated with Na2S was obtained. The response to the substance was as follows: Figure 2 .Depend on Figure 2 As can be seen, after Na2S pretreatment, the electrode showed no potential response to AA and Cys, but 20μM Na2S caused a potential change of approximately 45.5mV. This validates the effect of Na2S pretreatment on microelectrode response, preventing interference from sulfur-containing proteins and other electroactive substances, thereby achieving selective detection of hydrogen sulfide.

[0069] The morphology of the microelectrodes treated with Na2S was characterized by energy dispersive spectroscopy (EDS). Figure 3 As shown in Figures AD, C, Ag, and S elements are evenly distributed on the microelectrode. The results show that the AgNPs coating is evenly covered on the microelectrode surface and the pretreatment is uniform, which is the key to forming a selective interface. To further verify the elemental composition and oxidation state of Na2S pretreatment, we performed X-ray photoelectron spectroscopy (XPS) to characterize the electrochemical products and measured the Ag3d and S2p XPS spectra of the samples ( Figure 3E, F). The Ag3d spectrum consists of two peaks (373.80 and 367.83 eV), corresponding to the spin-orbit splitting 3d5 / 2 and 3d3 / 2, respectively. The peak at 373.80 eV represents the fitting results of Ag03d 3 / 2 and Ag+3d 3 / 2, respectively. The peak at 367.83 eV represents the fitting results of Ag03d 5 / 2 and Ag+3d 5 / 2, respectively, proving that AgNPs partially react to generate Ag+. The S2p spectrum shows two peaks at 162.25 and 161.70 eV, respectively, which are attributed to S 2- From the XPS spectra of Ag3d and S2p, it can be seen that the partially oxidized AgNPs and S 2- Combined, a layer of Ag2S film is formed and attached to the surface of the microelectrode.

[0070] The open circuit potential method can be implemented in a two-electrode system or a three-electrode system. In the two-electrode system, the working electrode is AgNPs-CFEs and the reference electrode is an Ag / AgCl electrode. In the three-electrode system, the working electrode is AgNPs-CFEs, the counter electrode is a Pt electrode, and the reference electrode is an Ag / AgCl electrode or a saturated calomel electrode.

[0071] Response curve of the silver nanoparticle-modified carbon fiber electrode pretreated with sodium sulfide to hydrogen sulfide: The analyte was added to the artificial cerebrospinal fluid (NaCl (126mM), KCl (2.4mM), KH2PO4 (0.5mM), MgCl2 (0.85mM), NaHCO3 (27.5mM), Na2SO4 (0.5mM), CaCl2 (1.1mM))) and detected by the open circuit potential method. When the open circuit potential method is used for measurement, no voltage is applied to the working electrode, but the potential difference between the working electrode and the reference electrode is directly measured. After the background voltage stabilizes, a certain amount of the analyte is added to the artificial cerebrospinal fluid, and the electrode voltage at this time is measured to obtain the first analyte concentration and the corresponding electrode voltage; subsequently, a fixed amount of the analyte is added to the artificial cerebrospinal fluid multiple times, so that the concentration of the analyte changes in a gradient, and the electrode voltage is measured each time the analyte concentration changes ( Figure 4 By gradually increasing the concentration of hydrogen sulfide, it can be observed that the potential curve changes with the concentration, thus obtaining the concentration curve ( Figure 4 The concentrations of hydrogen sulfide used were 2.5 μM, 10 μM, 20 μM, 40 μM, 80 μM, 120 μM, and 150 μM, respectively, and the standard curve of hydrogen sulfide obtained was V (mV) = -67.99C H2S (μM)–347.4(mV),R 2 =0.9942, and the detection range was 2.5–150 μM.

[0072] Example 2

[0073] Sodium sulfide-pretreated nanosilver carbon fiber microelectrodes for highly selective detection of hydrogen sulfide in living nervous systems

[0074] Microelectrodes were implanted into the hippocampus of anesthetized rats. We injected S 2- 100 μM artificial cerebrospinal fluid, such as Figure 5 As shown by the blue star, a potential drop can be observed after 300s. 2+ Artificial cerebrospinal fluid ( Figure 5 Black star), the potential almost returned to the initial baseline, proving that hydrogen sulfide can be detected by the electrode through the body fluid circulation and Cu 2+ The above results indicate that microelectrodes can track the changes of hydrogen sulfide in vivo and the physiological and pathological processes related to hydrogen sulfide.

Claims

1. A method for preparing a sodium sulfide pretreated carbon fiber microelectrode, comprising the following steps: 1) Silver nanoparticles were modified on the surface of carbon fiber microelectrodes by electrodeposition; In step 1), the electrolyte used in the electrodeposition method is a mixed solution containing 1 mmol / L KNO3 and 0.25 mmol / L AgNO3; The electrodeposition method uses a constant potential deposition method, with a voltage of -0.2 V for 200 s; The electrodeposition method is implemented in a two-electrode system or a three-electrode system; wherein, In the two-electrode system, the working electrode is the carbon fiber microelectrode, and the reference electrode is an Ag / AgCl electrode; in the three-electrode system, the working electrode is the carbon fiber microelectrode, the counter electrode is a Pt electrode, and the reference electrode is an Ag / AgCl electrode or a saturated calomel electrode; 2) Pre-treating the silver nanoparticle-modified carbon fiber microelectrode in a sodium sulfide solution to form a silver sulfide film on its surface; In step 2), the concentration of sodium sulfide in the sodium sulfide solution is 5 μM, the pretreatment is performed by open circuit potential method, and the treatment time is 5 minutes; The open circuit potential method is implemented in a two-electrode system or a three-electrode system; in the two-electrode system, the working electrode is the sodium sulfide pretreated carbon fiber microelectrode, and the reference electrode is an Ag / AgCl electrode; in the three-electrode system, the working electrode is the sodium sulfide pretreated carbon fiber microelectrode, the counter electrode is a Pt electrode, and the reference electrode is an Ag / AgCl electrode or a saturated calomel electrode; The carbon fiber microelectrode needs to be electrochemically activated before use, specifically as follows: first apply a +1.5 V potential for 80 s, then polarize at 0.1 V s -1 Cyclic voltammogram was scanned in the potential range of 0.0-1.0 V at a scan rate of 1.50 until a stable cyclic voltammogram was obtained; The carbon fiber microelectrode needs to be cleaned as follows before electrochemical activation: the carbon fiber microelectrode is ultrasonically cleaned in acetone, 3.0 mol / L HNO3 and 1.0 mol / L KOH solutions in sequence.

2. The sodium sulfide pretreated carbon fiber microelectrode prepared by the method according to claim 1.

3. Use of the sodium sulfide pretreated carbon fiber microelectrode according to claim 2 in the preparation of products for in vitro and / or in vivo detection of hydrogen sulfide.

4. The use according to claim 3, characterized in that: The living body includes the human body and animals with a central nervous system; The in vivo detection of hydrogen sulfide refers to the detection of hydrogen sulfide by open circuit potential method in the living brain; The hydrogen sulfide is hydrogen sulfide in artificial cerebrospinal fluid or a living central nervous system.

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