An Intracranial Nitric Oxide Electrochemical Sensor and Its Preparation Method

Abstract

The present invention discloses an intracranial nitric oxide electrochemical sensor and a preparation method thereof, belonging to the field of implantable sensing technology. The method includes the following steps: preparing acid-treated carbon nanotube nitric oxide sensing fibers; preparing acid-treated carbon nanotube silver-silver chloride sensing fibers; preparing an intracranial nitric oxide sensor based on acid-treated carbon nanotube fibers; and winding the acid-treated carbon nanotube nitric oxide sensing fibers and the acid-treated carbon nanotube silver-silver chloride sensing fibers together to obtain the intracranial nitric oxide electrochemical sensor. The advantages of the present invention are as follows: The excellent electrochemical specific surface area and rich oxygen-containing functional groups of the acid-treated carbon nanotube fibers promote the adsorption capacity for nitric oxide, enhance the reaction rate on the electrode surface, improve the sensor sensitivity, and lower the detection limit; the acid-treated carbon nanotube fibers can match the mechanical properties of biological tissues, and will not cause brain nerve inflammatory reactions and additional nitric oxide expression after being implanted into the brain, thus improving the accuracy of sensing.

Description

Technical Field

[0001] The present invention relates to the field of implantable sensing technology, and more particularly, to an intracranial nitric oxide electrochemical sensor and a preparation method thereof. Background Art

[0002] Nitric oxide is a free radical synthesized and released by neurons, glial cells, and endothelial cells in the brain, and participates in various physiological functions in the brain, such as vasodilation, synaptic plasticity, neuromodulation, and inflammation. For example, long-term potentiation in the hippocampus has been shown to be involved in regulating the learning and memory processes. Abnormal nitric oxide levels are associated with abnormal physiological activities such as immune responses, neurotoxicity, and cerebrovascular diseases. For example, when the concentration of nitric oxide is too high, the excess nitric oxide can react with superoxide anions to generate a highly reactive oxidant molecule - peroxynitrite, which is toxic to cells; while too low a concentration of nitric oxide can induce the occurrence of some neurological diseases. To fully understand the biochemical effects of nitric oxide in these physiological processes, it is crucial to develop sensing technologies that can quantitatively monitor the concentration of nitric oxide and to monitor the changes in the concentration of nitric oxide in the living brain in real time.

[0003] In recent decades, a variety of techniques for detecting the concentration of nitric oxide in the brain have been developed, such as the Griess method, fluorescence probes, electron spin resonance spectroscopy, and chemiluminescence. However, the limitation of these methods is that they cannot monitor the changes in the concentration of nitric oxide in tissues in real time. In contrast, electrochemical sensing technology can directly implant an electrochemical sensor into the brain to detect the changes in the concentration of nitric oxide in the target brain region in real time, with high temporal and spatial resolution, which has attracted extensive attention. Currently, various nitric oxide electrochemical sensors based on carbon fiber and platinum wire have been developed and have achieved certain effects in monitoring the concentration of nitric oxide in brain tissue. However, the practical application of electrochemical sensing technology in the body still faces major challenges. On the one hand, the concentration change of intracranial nitric oxide is usually in the range of several to more than ten nanomoles, while the detection sensitivity (0.1 - 100 pA·nM -1 ) and detection limit (not less than 5 nM) of the current electrochemical sensors cannot meet this requirement; on the other hand, electrochemical sensors mainly use carbon fiber and platinum wire as conductive substrate materials, and these materials are all rigid probe structures. The mechanical mismatch between such sensors and brain tissue after implantation will lead to severe neuroinflammatory reactions and be accompanied by overexpression of inducible nitric oxide synthase (iNOS). The induction of iNOS will lead to the production of additional excessive nitric oxide, which in turn affects the accuracy of the sensing and monitoring results. These problems severely limit the practical application of nitric oxide sensors in intracranial real-time monitoring.

[0004] In the related art, as disclosed in Chinese Patent Document CN101430302A, a method for preparing a nitric oxide sensor is provided. In this method, graphite powder is first mixed with paraffin oil to form a paste, which is then extruded into a polytetrafluoroethylene tube or a glass tube, and copper wires are led out to make a carbon paste electrode. The prepared carbon paste electrode is polished smooth, soaked sufficiently in a cetyltrimethylammonium bromide solution, then taken out and rinsed in water, and air-dried naturally to obtain a cetyltrimethylammonium bromide film electrode. Finally, a Nafion solution is dropped onto the surface of the cetyltrimethylammonium bromide film electrode to prepare a nitric oxide sensor with a cetyltrimethylammonium bromide and Nafion modified carbon paste electrode. However, this method does not provide any inspiration for the problem that existing nitric oxide electrochemical sensors will cause serious neuroinflammatory reactions and produce excessive nitric oxide after being implanted into the brain. Summary of the Invention

[0005] 1. Technical Problems to be Solved

[0006] In view of the problem in the prior art that existing nitric oxide electrochemical sensors will cause serious neuroinflammatory reactions and produce excessive nitric oxide after being implanted into the brain, the present invention provides a highly sensitive and accurate intracranial nitric oxide sensor based on acid-treated carbon nanotube fibers, which can realize real-time monitoring of the change of nitric oxide signal in the brain, has a low detection limit, high sensitivity, accurate signal without interference, and a wide range of applications.

[0007] 2. Technical Solutions

[0008] The object of the present invention is achieved by the following technical solutions.

[0009] A method for preparing an intracranial nitric oxide electrochemical sensor, the steps include,

[0010] Preparing acid-treated carbon nanotube nitric oxide sensing fibers:

[0011] Soak, stand, wash and dry the carbon nanotube fibers to obtain acid-treated carbon nanotube fibers;

[0012] Deposit platinum nanoparticles and polyeugenol on the surface of the acid-treated carbon nanotube fibers; and uniformly coat the diluted perfluorosulfonic acid-based polymer solution on the surface of the acid-treated carbon nanotube fibers after depositing platinum nanoparticles and polyeugenol to obtain acid-treated carbon nanotube nitric oxide sensing fibers;

[0013] Preparing acid-treated carbon nanotube silver-silver chloride sensing fibers:

[0014] Soak, stand, wash and dry the carbon nanotube fibers to obtain acid-treated carbon nanotube fibers;

[0015] Electrochemically deposit silver on the surface of the acid-treated carbon nanotube fibers to obtain silver-plated carbon nanotube fibers;

[0016] The acid-treated carbon nanotube fibers after silver plating are chlorinated to obtain silver-silver chloride acid-treated carbon nanotube fibers;

[0017] Prepare a PVB mixed solution and uniformly coat it on the surface of the silver-silver chloride acid-treated carbon nanotube fibers to obtain acid-treated carbon nanotube silver-silver chloride sensing fibers;

[0018] Prepare an intracranial nitric oxide sensor based on acid-treated carbon nanotube fibers:

[0019] Wind the acid-treated carbon nanotube nitric oxide sensing fibers and the acid-treated carbon nanotube silver-silver chloride sensing fibers together to form a helical structure to obtain an intracranial nitric oxide electrochemical sensor.

[0020] Furthermore, the specific steps for preparing the acid-treated carbon nanotube fibers are as follows:

[0021] Prepare 20 mL of a nitric acid solution with a concentration of 98%. Immerse the carbon nanotube fibers in the nitric acid solution, let it stand at 25 °C for 12 hours, wash with deionized water after standing, and dry after washing to obtain acid-treated carbon nanotube fibers.

[0022] Furthermore, the specific steps for preparing the acid-treated carbon nanotube nitric oxide sensing fibers are as follows:

[0023] Prepare 1×10 -3 mol / L potassium chloroplatinate - 0.1 mol / L potassium chloride solution as electrolyte A;

[0024] Use the acid-treated carbon nanotube fibers as the working electrode, the silver-silver chloride electrode as the reference electrode, and the platinum electrode as the counter electrode. Immerse the three electrodes in electrolyte A, and alternately apply voltages of 0.5 V and -0.7 V to the working electrode by the potentiostatic polarization method for a total of 10 seconds, and repeat this process 50 to 100 times;

[0025] Platinum nanoparticles formed by the reduced platinum element in potassium chloroplatinate are deposited on the surface of the acid-treated carbon nanotube fibers to obtain acid-treated carbon nanotube fibers deposited with platinum nanoparticles.

[0026] Furthermore, the specific steps for preparing the acid-treated carbon nanotube nitric oxide sensing fibers are as follows:

[0027] Prepare 60 mL of 0.1 mol / L sodium hydroxide solution, remove the oxygen in the sodium hydroxide solution with argon, and add 5 mmol / L to 15 mmol / L of eugenol as electrolyte B;

[0028] The acid-treated carbon nanotube fiber after depositing platinum nanoparticles is used as the working electrode, the silver-silver chloride electrode is used as the reference electrode, and the platinum electrode is used as the counter electrode. The three electrodes are immersed in electrolyte B, and the working electrode is scanned 10 times by cyclic voltammetry at a scanning rate of 20 mV s -1 , and the scanning range is 0 V to 0.7 V;

[0029] Eugenol is electrochemically polymerized on the surface of the working electrode to form a polyeugenol film. The polyeugenol is deposited on the surface of the acid-treated carbon nanotube fiber after depositing platinum nanoparticles, and the acid-treated carbon nanotube fiber after depositing platinum nanoparticles and polyeugenol is obtained.

[0030] Furthermore, the specific steps for preparing the acid-treated carbon nanotube nitric oxide sensing fiber are as follows:

[0031] A perfluorosulfonic acid polymer solution diluted to 1.5 wt% to 5 wt% is prepared. 5 μL of the diluted perfluorosulfonic acid polymer solution is evenly coated on the surface of the acid-treated carbon nanotube fiber after depositing platinum nanoparticles and polyeugenol. After the perfluorosulfonic acid polymer solution dries, a perfluorosulfonic acid film is formed, and the acid-treated carbon nanotube nitric oxide sensing fiber is obtained.

[0032] Furthermore, the specific steps for preparing the acid-treated carbon nanotube silver-silver chloride sensing fiber are as follows:

[0033] Prepare a 0.1 mol / L silver nitrate - 0.1 mol / L potassium nitrate solution as electrolyte C;

[0034] The acid-treated carbon nanotube fiber is used as the working electrode, the silver-silver chloride electrode is used as the reference electrode, and the platinum electrode is used as the counter electrode. The three electrodes are immersed in electrolyte C, and the working electrode is scanned 14 times by cyclic voltammetry at a scanning rate of 0.1 V s -1 , and the scanning range is -0.9 V to 0.9 V;

[0035] Silver particles formed by the silver element reduced from silver nitrate are electrochemically deposited on the surface of the acid-treated carbon nanotube fiber, and the silver-plated carbon nanotube fiber is obtained.

[0036] Furthermore, the specific steps for preparing the acid-treated carbon nanotube silver-silver chloride sensing fiber are as follows:

[0037] Prepare a 0.1 mmol / L hydrochloric acid - 0.01 mol / L potassium chloride solution as electrolyte D. The silver-plated carbon nanotube fiber is used as the working electrode, the silver-silver chloride electrode is used as the reference electrode, and the platinum electrode is used as the counter electrode. The three electrodes are immersed in electrolyte D, and the working electrode is scanned 4 times by cyclic voltammetry at a scanning rate of 0.05 V s -1, with a scanning range of -0.15V to 1.05V, the acid-treated carbon nanotube fibers after silver plating are chlorinated to obtain silver-silver chloride acid-treated carbon nanotube fibers.

[0038] Furthermore, the specific steps for preparing the acid-treated carbon nanotube silver-silver chloride sensing fiber are as follows:

[0039] Dissolve 1mg to 200mg of polyvinyl butyral resin, 1mg to 100mg of sodium chloride, 1mg to 100mg of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, and 1mg to 10mg of MWCNT in 1ml of methanol to obtain a PVB mixed solution;

[0040] Take 1 drop of the PVB mixed solution and evenly coat it on the surface of the silver-silver chloride acid-treated carbon nanotube fiber to obtain the acid-treated carbon nanotube silver-silver chloride sensing fiber.

[0041] Furthermore, the specific steps for preparing the intracranial nitric oxide sensor based on the acid-treated carbon nanotube fiber are as follows:

[0042] Arrange the sensing parts of the acid-treated carbon nanotube nitric oxide sensing fiber and the acid-treated carbon nanotube silver-silver chloride sensing fiber in parallel, with an axial displacement difference. Fix one end of the two fibers and the other end on a rotating device. Run the rotating device to wind the two fibers together to form a helical structure, obtaining the intracranial nitric oxide electrochemical sensor based on the acid-treated carbon nanotube fiber.

[0043] The intracranial nitric oxide electrochemical sensor prepared according to the above preparation method of the intracranial nitric oxide electrochemical sensor includes,

[0044] The acid-treated carbon nanotube nitric oxide sensing fiber and the acid-treated carbon nanotube silver-silver chloride sensing fiber, the sensing parts of the acid-treated carbon nanotube nitric oxide sensing fiber and the acid-treated carbon nanotube silver-silver chloride sensing fiber are wound around each other to form a helical structure;

[0045] The acid-treated carbon nanotube nitric oxide sensing fiber includes acid-treated nanotube fibers, platinum nanoparticles, polyeugenol, and a perfluorosulfonic acid film. The platinum nanoparticles and the polyeugenol are deposited on the surface of the acid-treated nanotube fibers, and the perfluorosulfonic acid film is evenly coated on the surface of the acid-treated nanotube fibers after depositing the nanoparticles and the polyeugenol;

[0046] The acid-treated carbon nanotube silver-silver chloride sensing fiber includes acid-treated nanotube fibers, silver particles, and a PVB mixed solution. The silver particles are deposited on the surface of the acid-treated nanotube fibers, and the PVB mixed solution is evenly coated on the surface of the acid-treated nanotube fibers after depositing the silver particles.

[0047] 3. Beneficial effects

[0048] Compared with the prior art, the advantages of the present invention are as follows:

[0049] The present invention uses acid-treated carbon nanotube fibers, which have excellent electrochemical specific surface area and abundant oxygen-containing functional groups, promoting the adsorption ability of carbon nanotube fibers to nitric oxide, enhancing the reaction rate on the electrode surface, significantly improving the sensitivity of the sensor, and reducing the detection limit.

[0050] The present invention uses acid-treated carbon nanotube fibers, which can match the mechanical properties of biological tissues and will not cause neuroinflammatory reactions and additional nitric oxide expression in the brain after implantation, thus significantly improving the accuracy of sensing. Brief description of the drawings

[0051] Figure 1 It is a schematic structural diagram of an intracranial electrochemical nitric oxide sensor in an embodiment of the present invention;

[0052] Figure 2 It is a schematic structural diagram of an acid-treated carbon nanotube nitric oxide sensing fiber in an embodiment of the present invention;

[0053] Figure 3 It is a schematic diagram of the nitric oxide adsorption ability of an acid-treated carbon nanotube nitric oxide sensing fiber in an embodiment of the present invention;

[0054] Figure 4 It is a schematic diagram of the performance of an acid-treated carbon nanotube nitric oxide sensing fiber in an embodiment of the present invention;

[0055] Figure 5 It is a schematic diagram of the biocompatibility of an acid-treated carbon nanotube nitric oxide sensing fiber in an embodiment of the present invention;

[0056] Figure 6 It is a schematic diagram of implanting an intracranial electrochemical nitric oxide sensor into a rat brain in an embodiment of the present invention;

[0057] Figure 7 It is a schematic diagram of the change in the nitric oxide concentration detected in the brain after implanting an intracranial electrochemical nitric oxide sensor made of acid-treated carbon nanotube fibers into a rat brain in an embodiment of the present invention;

[0058] Figure 8 It is a schematic diagram of the change in the nitric oxide concentration detected in a stroke disease model after implanting an intracranial electrochemical nitric oxide sensor into a rat brain in an embodiment of the present invention;

[0059] Figure 9This is a schematic diagram of the behavior of a rat in a stroke disease model detected after implanting an intracranial electrochemical nitric oxide sensor in a rat's brain in an embodiment of the present invention.

[0060] Description of reference numerals in the figure: 10, intracranial electrochemical nitric oxide sensor; 100, nitric oxide sensing fiber of acid-treated carbon nanotubes; 200, silver-silver chloride sensing fiber of acid-treated carbon nanotubes; 110, acid-treated nanotube fiber; 120, platinum nanoparticles; 130, polyeugenol; 140, perfluorosulfonic acid film. Detailed implementation manners

[0061] The present invention will be described in detail below in conjunction with the accompanying drawings of the specification and specific embodiments.

[0062] Embodiment 1

[0063] As Figure 1 shown, this solution provides an intracranial nitric oxide electrochemical sensor 10, including a nitric oxide sensing fiber 100 of acid-treated carbon nanotubes and a silver-silver chloride sensing fiber 200 of acid-treated carbon nanotubes. The nitric oxide sensing fiber 100 of acid-treated carbon nanotubes includes an acid-treated nanotube fiber 110, platinum nanoparticles 120, polyeugenol 130, and a perfluorosulfonic acid film 140, wherein the platinum nanoparticles 120 and polyeugenol 130 are deposited on the surface of the acid-treated nanotube fiber 110, and the perfluorosulfonic acid film 140 is coated on the surface of the acid-treated nanotube fiber 110 after depositing the nanoparticles 120 and polyeugenol 130. The silver-silver chloride sensing fiber of acid-treated carbon nanotubes includes an acid-treated nanotube fiber, a silver particle and a PVB mixed solution, the silver particle is deposited on the surface of the acid-treated nanotube fiber, and the PVB mixed solution is uniformly coated on the surface of the acid-treated nanotube fiber after depositing the silver particle.

[0064] The nitric oxide sensing fiber of acid-treated carbon nanotubes serves as a working electrode to sense nitric oxide signal molecules in the intracranial cavity, the silver-silver chloride sensing fiber of acid-treated carbon nanotubes serves as a reference electrode, and the sensing parts of the nitric oxide sensing fiber of acid-treated carbon nanotubes and the silver-silver chloride sensing fiber of acid-treated carbon nanotubes are arranged in parallel to form a helical structure.

[0065] The present invention electrochemically deposits active substances on acid-treated carbon nanotube fibers to develop a novel intracranial electrochemical nitric oxide sensor. The sensor utilizes the excellent specific surface area and rich oxygen-containing functional groups of carbon nanotube fibers. The specific surface area refers to the total area per unit mass of the material, which improves the adsorption ability of the electrode to nitric oxide in the solution, achieving a sensitivity of up to 3245 pA·nM -1 and a detection limit of up to 0.1 nmol / L.

[0066] The intracranial electrochemical nitric oxide sensor developed by the present invention has high flexibility, matches the mechanical properties of brain tissue, and will not cause inflammatory reactions or additional nitric oxide expression. In addition, the sensor also has high selectivity and stability, can be implanted into the target brain region to monitor the concentration changes of nitric oxide under different physiological states in real time, and has broad application prospects in the field of implantable sensors.

[0067] This embodiment discloses a preparation method for intracranial nitric oxide electrochemistry sensing, including the following steps:

[0068] Prepare acid-treated carbon nanotube nitric oxide sensing fiber:

[0069] Immerse the carbon nanotube fiber in 20 mL of nitric acid solution with a concentration of 98%, let it stand at 25°C for 12 hours, after standing, wash it with deionized water, and dry it after washing to obtain acid-treated carbon nanotube fiber;

[0070] By preparing 1×10 -3 mol / L potassium chloroplatinate - 0.1 mol / L potassium chloride solution, obtain electrolyte A. Use the obtained acid-treated carbon nanotube fiber as the working electrode, silver-silver chloride electrode as the reference electrode, and platinum electrode as the counter electrode. Immerse the three electrodes in electrolyte A, and alternately apply voltages of 0.5 V and -0.7 V to the working electrode by potentiostatic polarization method for a total of 10 seconds, and repeat this process 50 times.

[0071] In this step, the platinum element in potassium chloroplatinate is reduced to form platinum nanoparticles, thereby realizing the deposition of platinum nanoparticles on the surface of the acid-treated carbon nanotube fiber, and obtaining the acid-treated carbon nanotube fiber after depositing platinum nanoparticles.

[0072] Prepare 60 mL of 0.1 mol / L sodium hydroxide solution, remove the oxygen in the sodium hydroxide solution with argon, add 10 mmol / L eugenol to obtain electrolyte B. Use the acid-treated carbon nanotube fiber after depositing platinum nanoparticles as the working electrode, silver-silver chloride electrode as the reference electrode, and platinum electrode as the counter electrode. Immerse the three electrodes in electrolyte B, and perform cyclic voltammetry scanning on the working electrode for 10 cycles with a scanning rate of 20 mV s -1 , and the scanning range is from 0 V to 0.7 V.

[0073] In this step, eugenol is electrochemically polymerized on the surface of the working electrode to form a polyeugenol film. This process realizes the deposition of polyeugenol on the surface of the acid-treated carbon nanotube fiber after depositing platinum nanoparticles, and obtains the acid-treated carbon nanotube fiber after depositing platinum nanoparticles and polyeugenol.

[0074] Prepare a perfluorosulfonic acid-based polymer solution, dilute the perfluorosulfonic acid-based polymer solution to 5 wt%, take 5 μL of the diluted perfluorosulfonic acid-based polymer solution and evenly coat it on the surface of the acid-treated carbon nanotube fiber after depositing platinum nanoparticles and polyeugenol. After the perfluorosulfonic acid-based polymer solution dries, a perfluorosulfonic acid film is formed to obtain an acid-treated carbon nanotube nitric oxide sensing fiber. Here, wt% is the unit of weight (mass) percentage, representing the weight ratio and the proportion of a substance in a mixture.

[0075] As Figure 2 shown, it is a schematic structural diagram of the acid-treated carbon nanotube nitric oxide sensing fiber.

[0076] The acid-treated carbon nanotube nitric oxide sensing fiber prepared according to the above steps has an excellent specific surface area and abundant oxygen-containing functional groups, enhancing the adsorption ability of the sensing fiber to nitric oxide. It can be seen from this that the adsorption ability of the acid-treated carbon nanotube nitric oxide sensing fiber to nitric oxide is 11 times and 13 times higher than that of carbon fiber and platinum wire respectively.

[0077] As Figure 3 shown, it is a schematic diagram of the nitric oxide adsorption ability of the acid-treated carbon nanotube nitric oxide sensing fiber. As Figure 4 shown, it is a schematic diagram of the performance of the acid-treated carbon nanotube nitric oxide sensing fiber. The sensitivity of the acid-treated carbon nanotube nitric oxide sensing fiber prepared according to the above steps reaches 3245 pA·nM -1 , and the detection limit reaches 0.1 nmol / L, both of which are superior to the intracranial nitric oxide sensing reported so far.

[0078] As Figure 5 shown, it is a schematic diagram of the biocompatibility of the prepared acid-treated carbon nanotube nitric oxide sensing fiber. The mechanical properties of the acid-treated carbon nanotube nitric oxide sensing fiber prepared according to the above steps match those of brain tissue. Compared with rigid carbon fiber and platinum wire, the acid-treated carbon nanotube nitric oxide sensing fiber will not cause severe neuroinflammatory reactions and overexpression of iNOS after implantation, and thus will not affect the accuracy of the nitric oxide detection signal.

[0079] Among them, iNOS is inducible nitric oxide synthase induced after injury. Nitric oxide synthase (NOS) belongs to the nervous system, and its isoenzymes have three subtypes, namely neuronal nitric oxide synthase (nNOS) and endothelial nitric oxide synthase (eNOS) expressed under normal conditions and inducible nitric oxide synthase (iNOS) induced after injury.

[0080] Prepare an acid-treated carbon nanotube silver-silver chloride sensing fiber:

[0081] The carbon nanotube fibers were immersed in 20 mL of nitric acid solution with a concentration of 98%, and after standing at 25 °C for 12 hours, the carbon nanotube fibers were washed with deionized water. After the washing was completed, the carbon nanotube fibers were dried to obtain acid-treated carbon nanotube fibers;

[0082] An electrolyte solution C was prepared by mixing 0.1 mol / L silver nitrate and 0.1 mol / L potassium nitrate. The acid-treated carbon nanotube fibers were used as the working electrode, the silver-silver chloride electrode was used as the reference electrode, and the platinum electrode was used as the counter electrode. The three electrodes were immersed in the electrolyte solution C, and cyclic voltammetry was used to scan the working electrode 14 times at a scan rate of 0.1 V s -1 , and the scanning range was from -0.9 V to 0.9 V.

[0083] During this process, the silver element in silver nitrate was reduced to form silver particles, thereby electrochemically depositing silver on the surface of the acid-treated carbon nanotube fibers to obtain silver-plated carbon nanotube fibers.

[0084] An electrolyte solution D was prepared by mixing 0.1 mmol / L hydrochloric acid and 0.01 mol / L potassium chloride. The silver-plated carbon nanotube fibers were used as the working electrode, the silver-silver chloride electrode was used as the reference electrode, and the platinum electrode was used as the counter electrode. The three electrodes were immersed in the electrolyte solution D, and cyclic voltammetry was used to scan the working electrode 4 times at a scan rate of 0.05 V s -1 , and the scanning range was from -0.15 V to 1.05 V. The silver-plated acid-treated carbon nanotube fibers were chlorinated to obtain silver-silver chloride acid-treated carbon nanotube fibers;

[0085] 1 mg of polyvinyl butyral resin, 1 mg of sodium chloride, 1 mg of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer, and 1 mg of MWCNT (carbon nanotubes) were dissolved in 1 ml of methanol to obtain a PVB (polyvinyl butyral ester) mixed solution; 1 drop of the PVB mixed solution was evenly coated on the surface of the silver-silver chloride acid-treated carbon nanotube fibers to prepare acid-treated carbon nanotube silver-silver chloride sensing fibers.

[0086] Preparation of an intracranial nitric oxide sensor based on acid-treated carbon nanotube fibers:

[0087] The sensing parts of the acid-treated carbon nanotube nitric oxide sensing fibers and the acid-treated carbon nanotube silver-silver chloride sensing fibers were arranged in parallel and had a certain axial displacement difference. One end of the two fibers was fixed with a rotating motor shaft, and the other end was fixed with tape. The motor ran at a speed of 50 rad·min -1 , and the two fibers were wound together to form a helical structure to obtain an intracranial nitric oxide electrochemical sensor based on acid-treated carbon nanotube fibers.

[0088] As another implementation of this embodiment, the motor in the above steps can also run at 25 rad·min -1 , 75 rad·min -1 , 100 rad·min -1 , 200 rad·min -1 to wind the fiber bundles together.

[0089] In practical applications, as Figures 6 to 9 shown, it is a schematic diagram of an application example of a novel intracranial electrochemical nitric oxide sensor based on acid-treated carbon nanotube fibers.

[0090] Among them, as Figure 6 shown, it is a schematic diagram of implanting the sensor into the rat brain. As Figure 7 shown, it is a schematic diagram comparing the changes in the nitric oxide concentration detected by each nitric oxide sensor in the brain. L-arginine was locally injected into the rat brain to stimulate the production of nitric oxide. Compared with the nitric oxide sensor based on carbon fiber and platinum wire, the novel intracranial electrochemical nitric oxide sensor based on acid-treated carbon nanotube fibers successfully detected the changes in the nitric oxide concentration in the brain.

[0091] As Figures 8 to 9 shown, further using the nitric oxide sensor, the changes in the nitric oxide concentration in the cerebral cortex were studied in a rat model of ischemic stroke. As Figure 8 shown, it is a schematic diagram of the changes in the nitric oxide concentration detected in the stroke disease model after implanting the intracranial electrochemical nitric oxide sensor into the rat brain. The novel intracranial electrochemical nitric oxide sensor based on acid-treated carbon nanotube fibers showed a rapid and accurate response current. The nitric oxide concentration in the cerebral cortex increased significantly in the severe ischemic stroke group, while the change in the nitric oxide concentration was small in the mild ischemic stroke group. As Figure 9 shown, it is a schematic diagram of the behavior of rats detected in the stroke disease model after implanting the intracranial electrochemical nitric oxide sensor into the rat brain. The total moving distance and the number of feces of the rats undergoing severe ischemic stroke experiments were higher than those of the rats undergoing mild ischemic stroke experiments, which was consistent with the changes in nitric oxide in the cerebral cortex. This example can further demonstrate the potential of the novel intracranial electrochemical nitric oxide sensor based on acid-treated carbon nanotube fibers in brain science research.

[0092] Example 2

[0093] This embodiment discloses a preparation method for intracranial nitric oxide electrochemistry sensing, including the following steps,

[0094] Preparing acid-treated carbon nanotube nitric oxide sensing fibers:

[0095] The carbon nanotube fibers were immersed in 20 mL of nitric acid solution with a concentration of 98%, and left standing at 25 °C for 12 hours. After standing, they were washed with deionized water, and then dried to obtain acid-treated carbon nanotube fibers;

[0096] By preparing a 1×10 -3 mol / L potassium chloroplatinate - 0.1 mol / L potassium chloride solution, electrolyte A was obtained. The obtained acid-treated carbon nanotube fibers were used as the working electrode, the silver-silver chloride electrode was used as the reference electrode, and the platinum electrode was used as the counter electrode. The three electrodes were immersed in electrolyte A, and voltages of 0.5 V and -0.7 V were alternately applied to the working electrode by the potentiostatic polarization method for a total of 10 seconds, and this process was repeated 100 times.

[0097] In this step, the platinum element in potassium chloroplatinate was reduced to form platinum nanoparticles, thereby realizing the deposition of platinum nanoparticles on the surface of the acid-treated carbon nanotube fibers, and obtaining the acid-treated carbon nanotube fibers with deposited platinum nanoparticles.

[0098] Prepare 60 mL of 0.1 mol / L sodium hydroxide solution, remove the oxygen in the sodium hydroxide solution with argon, add 5 mmol / L eugenol to obtain electrolyte B. The acid-treated carbon nanotube fibers with deposited platinum nanoparticles were used as the working electrode, the silver-silver chloride electrode was used as the reference electrode, and the platinum electrode was used as the counter electrode. The three electrodes were immersed in electrolyte B, and the working electrode was scanned 10 times by cyclic voltammetry at a scanning rate of 20 mV s -1 , and the scanning range was from 0 V to 0.7 V.

[0099] In this step, eugenol was electrochemically polymerized on the surface of the working electrode to form a polyeugenol film. This process realized the deposition of polyeugenol on the surface of the acid-treated carbon nanotube fibers with deposited platinum nanoparticles, and obtained the acid-treated carbon nanotube fibers with deposited platinum nanoparticles and polyeugenol.

[0100] Prepare a perfluorosulfonic acid-based polymer solution, and dilute the perfluorosulfonic acid-based polymer solution to 2.5 wt%. Take 5 μL of the diluted perfluorosulfonic acid-based polymer solution and uniformly coat it on the surface of the acid-treated carbon nanotube fibers with deposited platinum nanoparticles and polyeugenol. After drying, a film was formed to obtain acid-treated carbon nanotube nitric oxide sensing fibers.

[0101] As Figure 2 shown, it is a schematic structural diagram of the acid-treated carbon nanotube nitric oxide sensing fibers.

[0102] The acid-treated carbon nanotube nitric oxide sensing fiber prepared according to the above steps has an excellent specific surface area and abundant oxygen-containing functional groups, enhancing the adsorption ability of the sensing fiber to nitric oxide. It can be seen therefrom that the adsorption ability of the acid-treated carbon nanotube nitric oxide sensing fiber to nitric oxide is 11 times and 13 times higher than that of carbon fiber and platinum wire, respectively.

[0103] As Figure 3 shown, it is a schematic diagram of the nitric oxide adsorption ability of the acid-treated carbon nanotube nitric oxide sensing fiber. As Figure 4 shown, it is a schematic diagram of the performance of the acid-treated carbon nanotube nitric oxide sensing fiber. The sensitivity of the acid-treated carbon nanotube nitric oxide sensing fiber prepared according to the above steps reaches 3245 pA·nM -1 , and the detection limit reaches 0.1 nmol / L, both of which are superior to the intracranial nitric oxide sensing reported so far.

[0104] As Figure 5 shown, it is a schematic diagram of the biocompatibility of the prepared acid-treated carbon nanotube nitric oxide sensing fiber. The mechanical properties of the acid-treated carbon nanotube nitric oxide sensing fiber prepared according to the above steps match those of brain tissue. Compared with rigid carbon fiber and platinum wire, the acid-treated carbon nanotube nitric oxide sensing fiber will not cause serious neuroinflammatory reactions and overexpression of iNOS after implantation, and thus will not affect the accuracy of nitric oxide detection signals.

[0105] Preparation of acid-treated carbon nanotube silver-silver chloride sensing fiber:

[0106] Immerse the carbon nanotube fiber in 20 mL of nitric acid solution with a concentration of 98%, and let it stand at 25 °C for 12 hours. Then wash the carbon nanotube fiber with deionized water, and dry the carbon nanotube fiber after the washing is completed to obtain the acid-treated carbon nanotube fiber;

[0107] Prepare electrolyte C by configuring 0.1 mol / L silver nitrate - 0.1 mol / L potassium nitrate solution. The acid-treated carbon nanotube fiber is used as the working electrode, the silver-silver chloride electrode is used as the reference electrode, and the platinum electrode is used as the counter electrode. Immerse the three electrodes in electrolyte C and perform cyclic voltammetry scanning on the working electrode for 14 cycles at a scanning rate of 0.1 V s -1 , and the scanning range is from -0.9 V to 0.9 V.

[0108] During this process, the silver element in silver nitrate is reduced to form silver particles, thereby electrochemically depositing silver onto the acid-treated carbon nanotube fiber to obtain the silver-plated carbon nanotube fiber.

[0109] Configure a 0.1 mmol / L hydrochloric acid - 0.01 mol / L potassium chloride solution as electrolyte D, the silver-plated carbon nanotube fiber as the working electrode, the silver-silver chloride electrode as the reference electrode, and the platinum electrode as the counter electrode. Immerse the three electrodes in electrolyte D and perform cyclic voltammetry scanning on the working electrode for 4 cycles at a scanning rate of 0.05 V s -1 , with a scanning range from -0.15 V to 1.05 V. Chlorinate the acid-treated carbon nanotube fiber after silver plating to obtain a silver-silver chloride acid-treated carbon nanotube fiber;

[0110] Dissolve 1 mg of polyvinyl butyral resin, 1 mg of sodium chloride, 1 mg of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer, and 1 mg of MWCNT (carbon nanotube) in 1 ml of methanol to obtain a PVB (polyvinyl butyral ester) mixed solution; take 1 drop of the PVB mixed solution and coat it on the silver-silver chloride acid-treated carbon nanotube fiber to prepare an acid-treated carbon nanotube silver-silver chloride sensing fiber.

[0111] Prepare an intracranial nitric oxide sensor based on acid-treated carbon nanotube fibers:

[0112] The sensing parts of the acid-treated carbon nanotube nitric oxide sensing fiber and the acid-treated carbon nanotube silver-silver chloride sensing fiber are arranged in parallel and have a certain axial displacement difference. One end of the two fibers is fixed by a rotating motor shaft, and the other end is fixed by tape. The motor runs at a speed of 50 rad·min -1 , and the two fibers are wound together to form a helical structure, obtaining a novel intracranial electrochemical nitric oxide sensor based on acid-treated carbon nanotube fibers.

[0113] As another implementation mode of this embodiment, the motor in the above steps can also run at speeds of 25 rad·min -1 , 75 rad·min -1 , 100 rad·min -1 , 200 rad·min -1 to wind the fiber bundle together.

[0114] Example 3

[0115] This embodiment discloses a preparation method for intracranial nitric oxide electrochemistry sensing, including the following steps,

[0116] Prepare acid-treated carbon nanotube nitric oxide sensing fibers:

[0117] Immerse the carbon nanotube fiber in 20 mL of a 98% nitric acid solution and let it stand at 25 °C for 12 hours. After standing, wash it with deionized water, and then dry it to obtain acid-treated carbon nanotube fibers;

[0118] By configuring a 1×10 -3 mol / L potassium chloroplatinate - 0.1 mol / L potassium chloride solution, electrolyte A is obtained. The acid-treated carbon nanotube fiber obtained is used as the working electrode, the silver-silver chloride electrode is used as the reference electrode, and the platinum electrode is used as the counter electrode. The three electrodes are immersed in electrolyte A, and voltages of 0.5 V and -0.7 V are alternately applied to the working electrode by potentiostatic polarization for 10 seconds, and this process is repeated 150 times.

[0119] In this step, the platinum element in potassium chloroplatinate is reduced to form platinum nanoparticles, thereby realizing the deposition of platinum nanoparticles on the surface of the acid-treated carbon nanotube fiber, and the acid-treated carbon nanotube fiber after depositing platinum nanoparticles is obtained.

[0120] 60 mL of 0.1 mol / L sodium hydroxide solution is configured, the oxygen in the sodium hydroxide solution is removed with argon, and 15 mmol / L eugenol is added to obtain electrolyte B. The acid-treated carbon nanotube fiber after depositing platinum nanoparticles is used as the working electrode, the silver-silver chloride electrode is used as the reference electrode, and the platinum electrode is used as the counter electrode. The three electrodes are immersed in electrolyte B, and the working electrode is scanned 10 times by cyclic voltammetry at a scanning rate of 20 mV s -1 , and the scanning range is from 0 V to 0.7 V.

[0121] In this step, eugenol is electrochemically polymerized on the surface of the working electrode to form a polyeugenol film. This process realizes the deposition of polyeugenol on the surface of the acid-treated carbon nanotube fiber after depositing platinum nanoparticles, and the acid-treated carbon nanotube fiber after depositing platinum nanoparticles and polyeugenol is obtained.

[0122] A perfluorosulfonic acid-based polymer solution is prepared, and the perfluorosulfonic acid-based polymer solution is diluted to 1.5 wt%. 5 μL of the diluted perfluorosulfonic acid-based polymer solution is evenly coated on the surface of the acid-treated carbon nanotube fiber after depositing platinum nanoparticles and polyeugenol. After the perfluorosulfonic acid-based polymer solution dries, a perfluorosulfonic acid film is formed, and the acid-treated carbon nanotube nitric oxide sensing fiber is obtained.

[0123] As Figure 2 shown, it is a schematic structural diagram of the acid-treated carbon nanotube nitric oxide sensing fiber.

[0124] The acid-treated carbon nanotube nitric oxide sensing fiber prepared according to the above steps has an excellent specific surface area and abundant oxygen-containing functional groups, enhancing the adsorption ability of the sensing fiber to nitric oxide. It can be seen from this that the adsorption ability of the acid-treated carbon nanotube nitric oxide sensing fiber to nitric oxide is 11 times and 13 times higher than that of carbon fiber and platinum wire respectively.

[0125] As Figure 3As shown, it is a schematic diagram of the NO adsorption capacity of the acid-treated carbon nanotube NO sensing fiber, as Figure 4 shown, it is a schematic diagram of the performance of the acid-treated carbon nanotube NO sensing fiber. The sensitivity of the acid-treated carbon nanotube NO sensing fiber prepared according to the above steps reached 3245 pA·nM -1 , and the detection limit reached 0.1 nmol / L, both of which are superior to the intracranial NO sensing reported so far.

[0126] As Figure 5 shown, it is a schematic diagram of the biocompatibility of the prepared acid-treated carbon nanotube NO sensing fiber. The mechanical properties of the acid-treated carbon nanotube NO sensing fiber prepared according to the above steps match those of brain tissue. Compared with rigid carbon fiber and platinum wire, the acid-treated carbon nanotube NO sensing fiber will not cause serious neuroinflammatory reactions and overexpression of iNOS after implantation, and thus will not affect the accuracy of the NO detection signal.

[0127] Preparation of acid-treated carbon nanotube silver-silver chloride sensing fiber:

[0128] Immerse the carbon nanotube fiber in 20 mL of 98% nitric acid solution and let it stand at 25 °C for 12 hours. Then wash the carbon nanotube fiber with deionized water and dry the carbon nanotube fiber after washing to obtain the acid-treated carbon nanotube fiber;

[0129] Prepare electrolyte C by configuring 0.1 mol / L silver nitrate - 0.1 mol / L potassium nitrate solution. Use the acid-treated carbon nanotube fiber as the working electrode, the silver-silver chloride electrode as the reference electrode, and the platinum electrode as the counter electrode. Immerse the three electrodes in electrolyte C and perform cyclic voltammetry scanning on the working electrode for 14 cycles at a scanning rate of 0.1 V s -1 , and the scanning range is from -0.9 V to 0.9 V.

[0130] During this process, the silver element in silver nitrate is reduced to form silver particles, thereby electrochemically depositing silver onto the acid-treated carbon nanotube fiber to obtain the silver-plated carbon nanotube fiber.

[0131] Prepare 0.1 mmol / L hydrochloric acid - 0.01 mol / L potassium chloride solution as electrolyte D. Use the silver-plated carbon nanotube fiber as the working electrode, the silver-silver chloride electrode as the reference electrode, and the platinum electrode as the counter electrode. Immerse the three electrodes in electrolyte D and perform cyclic voltammetry scanning on the working electrode for 4 cycles at a scanning rate of 0.05 V s -1 , and the scanning range is from -0.15 V to 1.05 V. Chlorinate the silver-plated acid-treated carbon nanotube fiber to obtain the silver-silver chloride acid-treated carbon nanotube fiber;

[0132] Dissolve 1 mg of polyvinyl butyral resin, 1 mg of sodium chloride, 1 mg of polyethylene oxide - polypropylene oxide - polyethylene oxide triblock copolymer, and 1 mg of MWCNT in 1 ml of methanol to obtain a PVB mixed solution; take 1 drop of the PVB mixed solution and coat it on the silver - silver chloride acid - treated carbon nanotube fiber to prepare an acid - treated carbon nanotube silver - silver chloride sensing fiber.

[0133] Prepare an intracranial nitric oxide sensor based on the acid - treated carbon nanotube fiber:

[0134] The sensing parts of the acid - treated carbon nanotube nitric oxide sensing fiber and the acid - treated carbon nanotube silver - silver chloride sensing fiber are arranged in parallel and have a certain axial displacement difference. One end of the two fibers is fixed by the rotating motor shaft, and the other end is fixed with tape. The motor runs at a speed of 50 rad·min -1 to wind the two fibers together to form a helical structure, obtaining a novel intracranial electrochemical nitric oxide sensor based on the acid - treated carbon nanotube fiber.

[0135] As another implementation mode of this embodiment, the motor in the above steps can also run at speeds of 25 rad·min -1 , 75 rad·min -1 , 100 rad·min -1 , 200 rad·min -1 to wind the fiber bundle together.

[0136] Example 4

[0137] This embodiment discloses a preparation method for intracranial nitric oxide electrochemistry sensing, including the following steps:

[0138] Prepare an acid - treated carbon nanotube nitric oxide sensing fiber:

[0139] Immerse the carbon nanotube fiber in 20 mL of 98% nitric acid solution and let it stand at 25 °C for 12 hours. After standing, wash it with deionized water and then dry it to obtain the acid - treated carbon nanotube fiber;

[0140] By preparing a 1×10 -3 mol / L potassium chloroplatinate - 0.1 mol / L potassium chloride solution, obtain electrolyte A. Use the obtained acid - treated carbon nanotube fiber as the working electrode, the silver - silver chloride electrode as the reference electrode, and the platinum electrode as the counter electrode. Immerse the three electrodes in electrolyte A and alternately apply voltages of 0.5 V and - 0.7 V to the working electrode by the potentiostatic polarization method for 10 seconds, and repeat this process 150 times.

[0141] In this step, the platinum element in potassium chloroplatinate is reduced to form platinum nanoparticles, thereby realizing the deposition of platinum nanoparticles on the surface of the acid-treated carbon nanotube fiber, and obtaining the acid-treated carbon nanotube fiber with deposited platinum nanoparticles.

[0142] Prepare 60 mL of 0.1 mol / L sodium hydroxide solution, remove the oxygen in the sodium hydroxide solution with argon, add 15 mmol / L eugenol to obtain electrolyte B. The acid-treated carbon nanotube fiber with deposited platinum nanoparticles is used as the working electrode, the silver-silver chloride electrode is used as the reference electrode, and the platinum electrode is used as the counter electrode. Immerse the three electrodes in electrolyte B and perform cyclic voltammetry scanning on the working electrode for 10 cycles at a scanning rate of 20 mV s -1 , and the scanning range is from 0 V to 0.7 V.

[0143] In this step, eugenol is electrochemically polymerized on the surface of the working electrode to form a polyeugenol film. This process realizes the deposition of polyeugenol on the surface of the acid-treated carbon nanotube fiber with deposited platinum nanoparticles, and obtains the acid-treated carbon nanotube fiber with deposited platinum nanoparticles and polyeugenol.

[0144] Prepare a perfluorosulfonic acid-based polymer solution and dilute the perfluorosulfonic acid-based polymer solution to 1.5 wt%. Take 5 μL of the diluted perfluorosulfonic acid-based polymer solution and evenly coat it on the surface of the acid-treated carbon nanotube fiber with deposited platinum nanoparticles and polyeugenol. After drying, a film is formed to obtain the acid-treated carbon nanotube nitric oxide sensing fiber.

[0145] As Figure 2 shown, it is a schematic structural diagram of the acid-treated carbon nanotube nitric oxide sensing fiber.

[0146] The acid-treated carbon nanotube nitric oxide sensing fiber prepared according to the above steps has excellent specific surface area and rich oxygen-containing functional groups, which enhance the adsorption ability of the sensing fiber to nitric oxide. It can be seen that the adsorption ability of the acid-treated carbon nanotube nitric oxide sensing fiber to nitric oxide is 11 times and 13 times higher than that of carbon fiber and platinum wire respectively.

[0147] As Figure 3 shown, it is a schematic diagram of the nitric oxide adsorption ability of the acid-treated carbon nanotube nitric oxide sensing fiber. As Figure 4 shown, it is a schematic diagram of the performance of the acid-treated carbon nanotube nitric oxide sensing fiber. The sensitivity of the acid-treated carbon nanotube nitric oxide sensing fiber prepared according to the above steps reaches 3245 pA·nM -1 , and the detection limit reaches 0.1 nmol / L, both of which are superior to the intracranial nitric oxide sensing reported so far.

[0148] As Figure 5As shown, it is a schematic diagram of the biocompatibility of the prepared acid-treated carbon nanotube nitric oxide sensing fiber. The mechanical properties of the acid-treated carbon nanotube nitric oxide sensing fiber prepared according to the above steps match those of brain tissue. Compared with rigid carbon fiber and platinum wire, the acid-treated carbon nanotube nitric oxide sensing fiber will not cause serious neuroinflammatory reactions and overexpression of iNOS after implantation, and thus will not affect the accuracy of nitric oxide detection signals.

[0149] Preparation of acid-treated carbon nanotube silver-silver chloride sensing fiber:

[0150] Immerse the carbon nanotube fiber in 20 mL of nitric acid solution with a concentration of 98%, let it stand at 25 °C for 12 hours, then wash the carbon nanotube fiber with deionized water, and dry the carbon nanotube fiber after the washing is completed to obtain acid-treated carbon nanotube fiber;

[0151] Prepare electrolyte C by configuring 2.5 mol / L silver nitrate - 2.5 mol / L potassium nitrate solution. The acid-treated carbon nanotube fiber is used as the working electrode, the silver-silver chloride electrode is used as the reference electrode, and the platinum electrode is used as the counter electrode. Immerse the three electrodes in electrolyte C and perform cyclic voltammetry scanning on the working electrode for 14 cycles at a scanning rate of 0.1 V s -1 , and the scanning range is from -0.9 V to 0.9 V.

[0152] During this process, the silver element in silver nitrate is reduced to form silver particles, thereby electrochemically depositing silver onto the acid-treated carbon nanotube fiber to obtain silver-plated carbon nanotube fiber.

[0153] Prepare electrolyte D by configuring 2.5 mmol / L hydrochloric acid - 2.5 mol / L potassium chloride solution. The silver-plated carbon nanotube fiber is used as the working electrode, the silver-silver chloride electrode is used as the reference electrode, and the platinum electrode is used as the counter electrode. Immerse the three electrodes in electrolyte D and perform cyclic voltammetry scanning on the working electrode for 4 cycles at a scanning rate of 0.05 V s -1 , and the scanning range is from -0.15 V to 1.05 V. Chlorinate the silver-plated acid-treated carbon nanotube fiber to obtain silver-silver chloride acid-treated carbon nanotube fiber;

[0154] Dissolve 100 mg of polyvinyl butyral resin, 50 mg of sodium chloride, 50 mg of polyethylene oxide - polypropylene oxide - polyethylene oxide triblock copolymer, and 5 mg of MWCNT in 1 ml of methanol to obtain a PVB mixed solution; take 1 drop of the PVB mixed solution and coat it on the silver-silver chloride acid-treated carbon nanotube fiber to prepare acid-treated carbon nanotube silver-silver chloride sensing fiber.

[0155] Preparation of an intracranial nitric oxide sensor based on acid-treated carbon nanotube fiber:

[0156] The sensing parts of the acid-treated carbon nanotube nitric oxide sensing fiber and the acid-treated carbon nanotube silver-silver chloride sensing fiber are arranged in parallel and have a certain axial displacement difference. One end of the two fibers is fixed by the rotating motor shaft, and the other end is fixed by tape. The motor runs at a speed of 50 rad·min -1 and winds the two fibers together to form a helical structure, obtaining a novel intracranial electrochemical nitric oxide sensor based on acid-treated carbon nanotube fibers.

[0157] As another implementation manner of this embodiment, the motor in the above steps can also run at 25 rad·min -1 , 75 rad·min -1 , 100 rad·min -1 , 200 rad·min -1 to wind the fiber bundle together.

[0158] Example 5

[0159] This embodiment discloses a preparation method for intracranial nitric oxide electrochemistry sensing, including the following steps.

[0160] Prepare the acid-treated carbon nanotube nitric oxide sensing fiber:

[0161] Immerse the carbon nanotube fiber in 20 mL of nitric acid solution with a concentration of 98%, and let it stand at 25°C for 12 hours. After standing, wash it with deionized water, and then dry it to obtain the acid-treated carbon nanotube fiber.

[0162] By preparing a 1×10 -3 mol / L potassium chloroplatinate - 0.1 mol / L potassium chloride solution, electrolyte A is obtained. Use the obtained acid-treated carbon nanotube fiber as the working electrode, the silver-silver chloride electrode as the reference electrode, and the platinum electrode as the counter electrode. Immerse the three electrodes in electrolyte A, and alternately apply a voltage of 0.5 V to -0.7 V to the working electrode by the potentiostatic polarization method for 10 seconds, and repeat this process 150 times.

[0163] In this step, the platinum element in potassium chloroplatinate is reduced to form platinum nanoparticles, thereby realizing the deposition of platinum nanoparticles on the surface of the acid-treated carbon nanotube fiber, and obtaining the acid-treated carbon nanotube fiber with deposited platinum nanoparticles.

[0164] Prepare 60 mL of 0.1 mol / L sodium hydroxide solution, remove the oxygen in the sodium hydroxide solution with argon, add 15 mmol / L eugenol to obtain electrolyte B. The acid-treated carbon nanotube fiber deposited with platinum nanoparticles is used as the working electrode, the silver-silver chloride electrode is used as the reference electrode, and the platinum electrode is used as the counter electrode. Immerse the three electrodes in electrolyte B and perform cyclic voltammetry scanning on the working electrode for 10 cycles at a scanning rate of 20 mV s -1 , and the scanning range is from 0 V to 0.7 V.

[0165] In this step, eugenol is electrochemically polymerized on the surface of the working electrode to form a polyeugenol film. This process realizes the deposition of polyeugenol on the surface of the acid-treated carbon nanotube fiber deposited with platinum nanoparticles, and the acid-treated carbon nanotube fiber deposited with platinum nanoparticles and polyeugenol is obtained.

[0166] Prepare a perfluorosulfonic acid-based polymer solution, dilute the perfluorosulfonic acid-based polymer solution to 1.5 wt%, take 5 μL of the diluted perfluorosulfonic acid-based polymer solution and uniformly coat it on the surface of the acid-treated carbon nanotube fiber deposited with platinum nanoparticles and polyeugenol, and form a film after drying to obtain an acid-treated carbon nanotube nitric oxide sensing fiber.

[0167] As Figure 2 shown, it is a schematic structural diagram of the acid-treated carbon nanotube nitric oxide sensing fiber.

[0168] The acid-treated carbon nanotube nitric oxide sensing fiber prepared according to the above steps has an excellent specific surface area and abundant oxygen-containing functional groups, enhancing the adsorption ability of the sensing fiber to nitric oxide. It can be seen that the adsorption ability of the acid-treated carbon nanotube nitric oxide sensing fiber to nitric oxide is 11 times and 13 times higher than that of carbon fiber and platinum wire respectively.

[0169] As Figure 3 shown, it is a schematic diagram of the nitric oxide adsorption ability of the acid-treated carbon nanotube nitric oxide sensing fiber. As Figure 4 shown, it is a schematic diagram of the performance of the acid-treated carbon nanotube nitric oxide sensing fiber. The sensitivity of the acid-treated carbon nanotube nitric oxide sensing fiber prepared according to the above steps reaches 3245 pA·nM -1 , and the detection limit reaches 0.1 nmol / L, both of which are superior to the intracranial nitric oxide sensing reported so far.

[0170] As Figure 5As shown, it is a schematic diagram of the biocompatibility of the prepared acid-treated carbon nanotube nitric oxide sensing fiber. The mechanical properties of the acid-treated carbon nanotube nitric oxide sensing fiber prepared according to the above steps match those of brain tissue. Compared with rigid carbon fiber and platinum wire, the acid-treated carbon nanotube nitric oxide sensing fiber will not cause severe neuroinflammatory reactions and overexpression of iNOS after implantation, and thus will not affect the accuracy of nitric oxide detection signals.

[0171] Preparation of acid-treated carbon nanotube silver-silver chloride sensing fiber:

[0172] Soak the carbon nanotube fiber in 20 mL of nitric acid solution with a concentration of 98%, and let it stand at 25 °C for 12 hours. Then wash the carbon nanotube fiber with deionized water and dry the carbon nanotube fiber after the washing is completed to obtain the acid-treated carbon nanotube fiber;

[0173] Prepare electrolyte C by configuring 5 mol / L silver nitrate - 5 mol / L potassium nitrate solution. The acid-treated carbon nanotube fiber is used as the working electrode, the silver-silver chloride electrode is used as the reference electrode, and the platinum electrode is used as the counter electrode. Immerse the three electrodes in electrolyte C and perform cyclic voltammetry scanning on the working electrode for 14 cycles at a scanning rate of 0.1 V s -1 , and the scanning range is from -0.9 V to 0.9 V.

[0174] During this process, the silver element in silver nitrate is reduced to form silver particles, thereby electrochemically depositing silver onto the acid-treated carbon nanotube fiber to obtain the silver-plated carbon nanotube fiber.

[0175] Prepare electrolyte D by configuring 5 mmol / L hydrochloric acid - 5 mol / L potassium chloride solution. The silver-plated carbon nanotube fiber is used as the working electrode, the silver-silver chloride electrode is used as the reference electrode, and the platinum electrode is used as the counter electrode. Immerse the three electrodes in electrolyte D and perform cyclic voltammetry scanning on the working electrode for 4 cycles at a scanning rate of 0.05 V s -1 , and the scanning range is from -0.15 V to 1.05 V. Chlorinate the silver-plated acid-treated carbon nanotube fiber to obtain the silver-silver chloride acid-treated carbon nanotube fiber;

[0176] Dissolve 200 mg of polyvinyl butyral resin, 100 mg of sodium chloride, 100 mg of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, and 10 mg of MWCNT (carbon nanotube) in 1 ml of methanol to obtain a PVB (polyvinyl butyral ester) mixed solution; take 1 drop of the PVB mixed solution and coat it on the silver-silver chloride acid-treated carbon nanotube fiber to prepare the acid-treated carbon nanotube silver-silver chloride sensing fiber.

[0177] Preparation of an intracranial nitric oxide sensor based on acid-treated carbon nanotube fiber:

[0178] The sensing parts of the acid-treated carbon nanotube nitric oxide sensing fiber and the acid-treated carbon nanotube silver-silver chloride sensing fiber are arranged in parallel and have a certain axial displacement difference. One end of the two fibers is fixed by a rotating motor shaft, and the other end is fixed by tape. The motor runs at a speed of 50 rad·min -1 , winding the two fibers together to form a helical structure, and a novel intracranial electrochemical nitric oxide sensor based on acid-treated carbon nanotube fibers is obtained.

[0179] As another implementation manner of this embodiment, the motor in the above steps can also run at speeds of 25 rad·min -1 , 75 rad·min -1 , 100 rad·min -1 , 200 rad·min -1 to wind the fiber bundle together.

[0180] The present invention and its implementation manners are schematically described above. The description is not restrictive. Without departing from the spirit or basic features of the present invention, the present invention can be implemented in other specific forms. What is shown in the drawings is only one of the implementation manners of the present invention, and the actual structure is not limited thereto. Any reference signs in the claims should not limit the claimed claims. Therefore, if those of ordinary skill in the art are inspired by it and, without departing from the purpose of this creation, design structurally similar ways and embodiments to this technical solution without creative efforts, they shall fall within the protection scope of this patent. In addition, the term "comprising" does not exclude other elements or steps, and the term "a" before an element does not exclude including "a plurality of" such elements. The multiple elements stated in the product claims can also be implemented by one element through software or hardware. First, second, etc. are used to indicate names and do not represent any specific order.

Claims

1. A preparation method of an intracranial nitric oxide electrochemical sensor, the steps including, Preparing an acid-treated carbon nanotube nitric oxide sensing fiber: Soaking, standing, washing and drying the carbon nanotube fiber to obtain an acid-treated carbon nanotube fiber; Depositing platinum nanoparticles and polyeugenol on the surface of the acid-treated carbon nanotube fiber; And uniformly coating a diluted perfluorosulfonic acid-based polymer solution on the surface of the acid-treated carbon nanotube fiber after depositing platinum nanoparticles and polyeugenol to obtain an acid-treated carbon nanotube nitric oxide sensing fiber; Preparing an acid-treated carbon nanotube silver-silver chloride sensing fiber: Soaking, standing, washing and drying the carbon nanotube fiber to obtain an acid-treated carbon nanotube fiber; Electrochemically depositing silver onto the surface of the acid-treated carbon nanotube fiber to obtain a silver-plated carbon nanotube fiber; Chlorinating the silver-plated acid-treated carbon nanotube fiber to obtain a silver-silver chloride acid-treated carbon nanotube fiber; Preparing a PVB mixed solution and uniformly coating it on the surface of the silver-silver chloride acid-treated carbon nanotube fiber to obtain an acid-treated carbon nanotube silver-silver chloride sensing fiber; Preparing an intracranial nitric oxide sensor based on the acid-treated carbon nanotube fiber: Winding the acid-treated carbon nanotube nitric oxide sensing fiber and the acid-treated carbon nanotube silver-silver chloride sensing fiber together to form a helical structure to obtain an intracranial nitric oxide electrochemical sensor.

2. The preparation method of the intracranial nitric oxide electrochemical sensor according to claim 1, characterized in that, The specific steps for preparing the acid-treated carbon nanotube fiber are: Preparing 20 mL of a nitric acid solution with a concentration of 98%, soaking the carbon nanotube fiber in the nitric acid solution, standing at 25 °C for 12 hours, washing with deionized water after standing, and drying after washing to obtain an acid-treated carbon nanotube fiber.

3. The preparation method of the intracranial nitric oxide electrochemical sensor according to claim 1, characterized in that, The specific steps for preparing the acid-treated carbon nanotube nitric oxide sensing fiber are: Configure 1×10 -3 mol / L potassium chloroplatinate - 0.1 mol / L potassium chloride solution as electrolyte A; Using the acid-treated carbon nanotube fiber as the working electrode, the silver-silver chloride electrode as the reference electrode, and the platinum electrode as the counter electrode, immersing the three electrodes in electrolyte A, and alternately applying voltages of 0.5 V and -0.7 V to the working electrode by the potentiostatic polarization method for a total of 10 seconds, repeating this process 50 to 100 times; Platinum nanoparticles formed by the reduced platinum element in potassium chloroplatinate are deposited on the surface of the acid-treated carbon nanotube fiber to obtain an acid-treated carbon nanotube fiber after depositing platinum nanoparticles.

4. The preparation method of the intracranial nitric oxide electrochemical sensor according to claim 1, characterized in that, The specific steps for preparing the acid-treated carbon nanotube nitric oxide sensing fiber are: Preparing 60 mL of a 0.1 mol / L sodium hydroxide solution, removing the oxygen in the sodium hydroxide solution with argon, and adding 5 mmol / L to 15 mmol / L of eugenol as electrolyte B; The acid-treated carbon nanotube fiber after depositing platinum nanoparticles was used as the working electrode, the silver-silver chloride electrode was used as the reference electrode, and the platinum electrode was used as the counter electrode. The three electrodes were immersed in electrolyte B, and the working electrode was scanned 10 times by cyclic voltammetry at a scanning rate of 20 mV s -1 , and the scanning range was 0 V to 0.7 V; Electrochemically polymerizing eugenol on the surface of the working electrode to form a polyeugenol film, and polyeugenol is deposited on the acid-treated carbon nanotube fiber after depositing platinum nanoparticles to obtain an acid-treated carbon nanotube fiber after depositing platinum nanoparticles and polyeugenol.

5. The preparation method of the intracranial nitric oxide electrochemical sensor according to claim 1, characterized in that The specific steps for preparing the acid-treated carbon nanotube nitric oxide sensing fiber are as follows: Prepare a perfluorosulfonic acid polymer solution diluted to 1.5 wt% - 5 wt%. Take 5 μL of the diluted perfluorosulfonic acid polymer solution and evenly coat it on the surface of the acid-treated carbon nanotube fiber after depositing platinum nanoparticles and polyeugenol. After the perfluorosulfonic acid polymer solution dries, a perfluorosulfonic acid thin film is formed to obtain the acid-treated carbon nanotube nitric oxide sensing fiber.

6. The preparation method of the intracranial nitric oxide electrochemical sensor according to claim 1, characterized in that The specific steps for preparing the acid-treated carbon nanotube silver-silver chloride sensing fiber are as follows: Prepare a 0.1 mol / L silver nitrate - 0.1 mol / L potassium nitrate solution as electrolyte C; The acid-treated carbon nanotube fiber was used as the working electrode, the silver-silver chloride electrode was used as the reference electrode, and the platinum electrode was used as the counter electrode. The three electrodes were immersed in electrolyte C, and the working electrode was scanned 14 times by cyclic voltammetry at a scan rate of 0.1 V s -1 , and the scanning range was -0.9 V to 0.9 V; Silver particles formed by the reduction of silver elements in silver nitrate are electrochemically deposited on the surface of the acid-treated carbon nanotube fiber to obtain the silver-plated carbon nanotube fiber.

7. The preparation method of the intracranial nitric oxide electrochemical sensor according to claim 1, characterized in that The specific steps for preparing the acid-treated carbon nanotube silver-silver chloride sensing fiber are as follows: Prepare a 0.1 mmol / L hydrochloric acid - 0.01 mol / L potassium chloride solution as electrolyte D. Use the silver-plated carbon nanotube fiber as the working electrode, the silver-silver chloride electrode as the reference electrode, and the platinum electrode as the counter electrode. Immerse the three electrodes in electrolyte D and perform cyclic voltammetry scanning on the working electrode for 4 cycles at a scanning rate of 0.05 V s -1 , with a scanning range of -0.15 V to 1.05 V, to chlorinate the acid-treated carbon nanotube fiber after silver plating, obtaining a silver-silver chloride acid-treated carbon nanotube fiber.

8. The preparation method of the intracranial nitric oxide electrochemical sensor according to claim 1, characterized in that The specific steps for preparing the acid-treated carbon nanotube silver-silver chloride sensing fiber are as follows: Dissolve 1 mg - 200 mg of polyvinyl butyral resin, 1 mg - 100 mg of sodium chloride, 1 mg - 100 mg of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer, and 1 mg - 10 mg of MWCNT in 1 ml of methanol to obtain a PVB mixed solution; Take 1 drop of the PVB mixed solution and evenly coat it on the surface of the silver-silver chloride acid-treated carbon nanotube fiber to obtain the acid-treated carbon nanotube silver-silver chloride sensing fiber.

9. The preparation method of the intracranial nitric oxide electrochemical sensor according to claim 1, characterized in that The specific steps for preparing the intracranial nitric oxide sensor based on the acid-treated carbon nanotube fiber are as follows: Arrange the sensing parts of the acid-treated carbon nanotube nitric oxide sensing fiber and the acid-treated carbon nanotube silver-silver chloride sensing fiber in parallel, with an axial displacement difference. Fix one end of the two fibers and the other end on a rotating device. Run the rotating device to wind the two fibers together to form a helical structure, obtaining the intracranial nitric oxide electrochemical sensor based on the acid-treated carbon nanotube fiber.

10. An intracranial nitric oxide electrochemical sensor prepared by the method for preparing an intracranial nitric oxide electrochemical sensor according to any one of claims 1-9, characterized in that, Including The acid-treated carbon nanotube nitric oxide sensing fiber and the acid-treated carbon nanotube silver-silver chloride sensing fiber, the sensing parts of the acid-treated carbon nanotube nitric oxide sensing fiber and the acid-treated carbon nanotube silver-silver chloride sensing fiber are wound around each other to form a helical structure; The acid-treated carbon nanotube nitric oxide sensing fiber includes an acid-treated nanotube fiber, platinum nanoparticles, polyeugenol, and a perfluorosulfonic acid thin film. The platinum nanoparticles and the polyeugenol are deposited on the surface of the acid-treated nanotube fiber, and the perfluorosulfonic acid thin film is evenly coated on the surface of the acid-treated nanotube fiber after depositing the nanoparticles and the polyeugenol; The acid-treated carbon nanotube silver-silver chloride sensing fiber comprises an acid-treated nanotube fiber, silver particles and a PVB mixed solution. The silver particles are deposited on the surface of the acid-treated nanotube fiber, and the PVB mixed solution is uniformly coated on the surface of the acid-treated nanotube fiber after the silver particles are deposited.

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