Fiber-based organic photoelectrochemical transistor uric acid sensor and method of making the same

Abstract

The application provides a fiber-based organic photoelectrochemical transistor uric acid sensor and a preparation method thereof. The fiber-based organic photoelectrochemical transistor uric acid sensor is obtained by growing Fe-MOF@PANI on the surface of a conductive fiber, then modifying uric acid oxidase and a biocompatible film solution as a gate electrode of the transistor, using the fiber loaded with a semiconductor material as a source-drain electrode of the transistor, and dropping a gel electrolyte. The organic photoelectrochemical transistor uric acid sensor uses a fiber-based material as an electrode, a photosensitive material and a sensing substance are modified on the gate electrode, the photosensitive material makes electrons jump to the surface of the electrode under light conditions, the channel current is regulated, and the sensing substance is used to detect uric acid. The uric acid sensor can work under zero gate bias, reduces the background signal and interference, shows a good current response to different concentrations of uric acid, and has great market promotion value.

Description

Technical Field

[0001] This invention relates to the field of photoelectric transistor sensor technology, and in particular to a fiber-based organic photoelectric chemical transistor uric acid sensor and its preparation method. Background Technology

[0002] Gout is a common disease caused by high levels of uric acid in the body. In addition to gout, high uric acid levels can also lead to kidney and cardiovascular diseases. Therefore, it is essential to monitor uric acid levels in the body. Currently, many types of uric acid sensors are available on the market, but they all have different drawbacks, such as high cost and portability. Finding a fast and accurate way to detect uric acid levels in the body is crucial for monitoring human health.

[0003] In the prior art, an invention patent (application number CN 201811162927.X) discloses a lanthanide MOF spun fiber membrane as a uric acid sensor and its preparation, applied to the quantitative detection of uric acid in human urine. The preparation process includes the synthesis of Eu-PTA-MOF powder, the synthesis of copolymer PMMA / PVP, the preparation of electrospinning solution, the preparation of nanofiber membrane, the cutting of nanofiber membrane, the insertion of the cut membrane into a cuvette, and the recording of fluorescence spectral data. The prepared electrospun fiber membrane utilizes Eu... 3+ The membrane exhibits various characteristic blue fluorescence patterns, and uric acid quenches the fluorescence of the electrospun fiber membrane, enabling it to detect uric acid. However, the electrospun fiber membrane only shows good fluorescence detection stability at pH 4.5–8.0, while gout patients often experience a decrease in pH due to increased uric acid secretion, limiting the application of this uric acid sensor. Furthermore, the fiber membrane relies on Eu... 3+ The fluorescence effect of uric acid detection is time-consuming, has low efficiency, and can only perform qualitative detection, making it unsuitable for detecting uric acid levels in patients with gout.

[0004] Organic photoelectrochemical transistors (OPECTs) are an emerging optoelectronic technology that combines organic electrochemical transistors (OECTs) with photoelectrochemical processes (PECs). This technology inherits the advantages of both OECT and PEC sensors, possessing large signal amplification and ease of miniaturization. OECT sensors show promising applications in biosensing, logic circuits, and immunosensing. If the advantages of OECTs—good biocompatibility, low detection limit, and high signal amplification—can be utilized and combined with PEC methods for uric acid detection, it will be of great significance in solving the aforementioned problems and providing a reliable detection method for gout patients.

[0005] In view of this, it is necessary to design an improved fiber-based organic photoelectrochemical transistor uric acid sensor and its preparation method to solve the above problems. Summary of the Invention

[0006] The present invention aims to provide a fiber-based organic photoelectrochemical transistor uric acid sensor and its preparation method. Fe-MOF@PANI is grown on the surface of conductive fibers, and a sensing material is modified to serve as the gate of the transistor. Simultaneously, the structure of Fe-MOF@PANI is controlled by adjusting parameters to improve transmission performance, enabling high photoelectric response and achieving the conversion of light energy into electrical energy. This, in conjunction with the sensing material, facilitates the detection of uric acid. This uric acid sensor improves the sensitivity of uric acid detection while operating at zero gate bias, reducing interference, and exhibiting good current response to different concentrations of uric acid, thus possessing significant market potential.

[0007] To achieve the above-mentioned objective, this invention provides a method for preparing a fiber-based organic photoelectrochemical transistor uric acid sensor, comprising the following steps:

[0008] S1. Surface-treat the conductive fibers, place them in a reaction vessel containing a mixed solution, and control the reaction temperature and time to prepare Fe-MOF@PANI composite conductive fibers; the mixed solution includes a complexing agent, an iron salt solution, an organic solvent, a dopant, and an aniline monomer;

[0009] S2. The Fe-MOF@PANI composite conductive fiber obtained in step S1 is surface treated, placed in a uric acid oxidase solution, and soaked at 2-4°C for 22-26 hours. After removal, it is air-dried naturally. Then, it is placed in a biocompatible membrane solution and soaked for 3-5 hours. After removal, it is air-dried naturally and used as the gate of the organic photoelectrochemical transistor uric acid sensor. The air-drying temperature for both steps is 2-4°C.

[0010] S3. Use the fiber with attached semiconductor material as the source and drain of the organic photoelectrochemical transistor uric acid sensor, and place it parallel to the gate of step S2 at a certain distance. Add gel electrolyte to obtain the fiber-based organic photoelectrochemical transistor uric acid sensor.

[0011] As a further improvement of the present invention, in step S1, the reaction temperature is 120-200°C and the time is 8-24 hours.

[0012] As a further improvement of the present invention, in step S1, the molar concentration ratio of the complexing agent to the aniline monomer is (0.5-3.0):1; the molar concentration ratio of the complexing agent to the iron salt solution is (1.6-2.4):1.

[0013] As a further improvement of the present invention, in step S1, the complexing agent is 2-aminoterephthalic acid; the iron salt solution includes one of ferric chloride hexahydrate, ferric chloride, ferric nitrate nonahydrate, and ferric sulfide.

[0014] As a further improvement of the present invention, in step S2, the concentration of the urate oxidase is 5-15 mg / ml, and the concentration of the biocompatible membrane solution is 5%-25%.

[0015] As a further improvement of the present invention, in step S1, the dopant includes one of acetic acid, hypochlorous acid, hydrofluoric acid and carbonic acid; the organic solvent includes any one of N,N-dimethylformamide, dimethylacetamide, dimethylpropionamide, diethylformamide or diethylacetamide.

[0016] As a further improvement of the present invention, in step S1, the conductive fiber includes one of carbon fiber, metal fiber or chemical fiber woven with a conductive medium; in step S2, the biocompatible membrane solution is a perfluorosulfonic acid type polymer solution; in step S3, the fiber with attached semiconductor material includes one of fiber loaded with PEDOT:PSS, polyaniline, polypyrrole, or polythiophene composite conductive fiber formed by in-situ polymerization.

[0017] As a further improvement of the present invention, in step S1, the surface treatment step is as follows: the fiber to be treated is placed in deionized water, anhydrous ethanol and acetone solution in sequence, and ultrasonically cleaned for 10-20 minutes in each solution, then taken out and dried to obtain a clean fiber surface; in step S2, the surface treatment is to clean the Fe-MOF@PANI composite conductive fiber in sequence with anhydrous ethanol and organic solvent of the same type as the mixed solution to remove unreacted impurities.

[0018] The present invention also provides a fiber-based organic photoelectrochemical transistor uric acid sensor, which is prepared by the preparation method of the fiber-based organic photoelectrochemical transistor uric acid sensor described in any one of the above claims; the fiber-based organic photoelectrochemical transistor uric acid sensor uses fiber as a substrate, and achieves the detection of uric acid by controlling the gate voltage and the chemical reaction of Fe-MOF@PANI material and uric acid oxidase on the gate, resulting in a change in the channel current.

[0019] As a further improvement of the present invention, the fiber-based organic photoelectrochemical transistor uric acid sensor has a uric acid concentration detection range of 1 nM to 10 mM, a detection limit of 1 nM, and a detection response time of 50 s.

[0020] The beneficial effects of this invention are:

[0021] 1. This invention discloses a fiber-based organic photoelectrochemical transistor uric acid sensor and its preparation method. The sensor is assembled by growing Fe-MOF@PANI on the surface of conductive fibers, modifying it with uric acid oxidase and a biocompatible membrane solution as the gate of the transistor, using fibers loaded with semiconductor materials as the source and drain electrodes of the photoelectrochemical transistor, and adding a gel electrolyte. This organic photoelectrochemical crystal uric acid sensor uses a fiber substrate as the electrode, with photosensitive materials and sensing substances modified on the gate. The photosensitive material allows electrons to jump to the electrode surface upon illumination, enabling regulation of the channel current and synergistic detection of uric acid with the sensing substance. This uric acid sensor improves the sensitivity of uric acid detection while operating at zero gate bias, simplifying the sensor structure, reducing background signal and interference, and exhibiting good current response to different concentrations of uric acid, thus possessing significant market potential.

[0022] 2. This invention, through temperature and time control during the preparation of Fe-MOF@PANI composite conductive fibers, generates a regularly structured photosensitive material on the surface of the conductive fibers, improving transmission performance and enabling high photoelectric response, thus achieving the conversion of light energy into electrical energy. Furthermore, this invention utilizes polyaniline linkers to anchor the photosensitive material to the conductive fibers, enhancing the bonding force between the two. The presence of the Fe-MOF structure promotes the in-situ polymerization of aniline monomers on the fiber surface without further intervention, and this in-situ polymerization process also facilitates the formation of a uniform Fe-MOF structure. Polyaniline possesses good conductivity, constructing a conductive network between the fiber substrate and the photosensitive material, thereby improving conductivity. Polyaniline can also adjust the conductivity of Fe-MOF, increasing its absorption of visible light, further enhancing its photoelectric response, improving the sensitivity of uric acid detection, and shortening the detection time.

[0023] 3. By limiting the ratio of complexing agent, aniline monomer, and iron salt solution in the preparation of Fe-MOF@PANI composite conductive fibers, this invention achieves an appropriate amount of Fe-MOF and PANI generated on the surface of the conductive fibers, realizing a synergistic promoting effect between the two during the generation process. This results in a stable Fe-MOF@PANI structure on the surface of the conductive fibers, which also has excellent biomolecular affinity and can protect the enzyme from the effects of harsh environments. Further modification of the composite conductive fibers with uricase and biocompatible membrane solution further improves the selectivity and sensitivity of the sensor.

[0024] 4. The fiber-based organic photoelectrochemical transistor uric acid sensor of this invention detects uric acid in real time under illumination by detecting the current; and realizes quantitative detection by reflecting the uric acid concentration based on the current intensity. Its uric acid concentration detection range is 1 nM to 10 mM, with a detection limit of 1 nM and a detection response time of 50 s, overcoming the shortcomings of traditional sensors such as long response time, high requirement for uric acid concentration, and only qualitative detection. This uric acid sensor uses fiber as the substrate for the sensor electrode, combining the excellent flexibility of fiber with the electrode, making it applicable to the field of flexible electronics; moreover, the preparation method is simple and controllable, and the materials are readily available. The prepared fiber-based organic photoelectrochemical transistor uric acid sensor achieves specific detection of uric acid and has good application prospects. Attached Figure Description

[0025] Figure 1 The graph shows the detection results of different uric acid concentrations using the fiber-based organic photoelectrochemical transistor uric acid sensor of Example 1.

[0026] Figure 2 The images shown are electron microscope (EM) images of the gate of the uric acid sensor of the fiber-based organic photoelectrochemical transistor in Examples 1 and 1-2.

[0027] Figure 3 The graph shows the detection results of uric acid at the same concentration using the fiber-based organic photoelectrochemical transistor uric acid sensor of Example 1 and Comparative Examples 1-2.

[0028] Figure 4 The image shows the detection results of the fiber-based organic photoelectrochemical transistor uric acid sensor of Example 1 for different solutions. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] It should also be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0031] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0032] A method for preparing a fiber-based organic photoelectrochemical transistor uric acid sensor includes the following steps:

[0033] S1. Surface-treat the conductive fibers, place them in a reaction vessel containing a mixed solution, and control the reaction temperature and time to prepare Fe-MOF@PANI composite conductive fibers; the mixed solution includes a complexing agent, iron salt solution, organic solvent, dopant, and aniline monomer;

[0034] S2. The Fe-MOF@PANI composite conductive fiber obtained in step S1 is surface treated, placed in uric acid oxidase solution, and soaked at 2-4℃ for 22-26 hours. After removal, it is naturally air-dried. Then it is placed in biocompatible membrane solution and soaked for 3-5 hours. After removal, it is naturally air-dried and used as the gate of the organic photoelectrochemical transistor uric acid sensor. The temperature of natural air drying is 2-4℃ for both times.

[0035] S3. Use the fiber with attached semiconductor material as the source and drain of the organic photoelectrochemical transistor uric acid sensor, and place it parallel to the gate of step S2 at a certain distance. Add gel electrolyte to obtain the fiber-based organic photoelectrochemical transistor uric acid sensor.

[0036] Specifically, this organic photoelectrochemical crystal uric acid sensor uses a fiber substrate as the electrode, with a photosensitive material and sensing substance modified on the gate. The photosensitive material allows electrons to jump to the electrode surface upon illumination, enabling regulation of the channel current and, in conjunction with the sensing substance, achieving uric acid detection. This uric acid sensor improves detection sensitivity while operating at zero gate bias, simplifying the sensor structure, reducing background signal and interference, and exhibiting excellent current response to different concentrations of uric acid, thus possessing significant market potential.

[0037] Specifically, in step S1, the reaction temperature is 120–200℃, and the time is 8–24 h. Thus, by controlling the temperature and time during the preparation of Fe-MOF@PANI composite conductive fibers, a regularly structured photosensitive material is generated on the surface of the conductive fibers, improving transmission performance and giving it high photoelectric response, thus realizing the conversion of light energy into electrical energy. Furthermore, this invention utilizes polyaniline linkers to anchor the photosensitive material to the conductive fibers, improving the bonding force between the photosensitive material and the conductive fibers. The presence of the Fe-MOF (iron-based metal-organic framework) structure promotes the in-situ polymerization of aniline monomers on the fiber surface without further intervention. The in-situ polymerization process of aniline monomers also facilitates the formation of a uniform Fe-MOF structure. Polyaniline has good conductivity, constructing a conductive network between the fiber substrate and the photosensitive material, improving conductivity. Polyaniline can also adjust the conductivity of Fe-MOF, increasing its absorption of visible light, further improving its photoelectric response, enhancing the sensitivity of uric acid detection, and shortening the detection time.

[0038] The molar concentration ratio of the complexing agent to the aniline monomer is (0.5–3.5):1; the molar concentration ratio of the complexing agent to the iron salt solution is (1.6–2.4):1; preferably 2:1. By limiting the ratio of complexing agent, aniline monomer, and iron salt solution in the preparation of Fe-MOF@PANI composite conductive fibers, the amount of Fe-MOF and PANI (polyaniline) generated on the surface of the conductive fibers is appropriate, achieving a synergistic promoting effect between the two in the generation process. This results in a stable Fe-MOF@PANI structure on the surface of the conductive fibers, which also has excellent biomolecular affinity and can protect the enzyme from the effects of harsh environments. After further modifying the composite conductive fibers with uric acid oxidase and a biocompatible membrane solution, the selectivity and sensitivity of the fiber-based organic photoelectrochemical transistor uric acid sensor are further improved.

[0039] More specifically, in step S1, the complexing agent is 2-aminoterephthalic acid; the iron salt solution includes one of ferric chloride hexahydrate, ferric chloride, ferric nitrate nonahydrate, and ferric sulfide. The dopant includes one of acetic acid, hypochlorous acid, hydrofluoric acid, and carbonic acid; the organic solvent includes one of N,N-dimethylformamide (DMF), dimethylacetamide (DMAC), dimethylpropionamide (DMP), diethylformamide (DEF), or diethylacetamide (DEAC).

[0040] In step S2, the concentration of uricase is 5–15 mg / ml, and the concentration of the biocompatible membrane solution is 5%–25%. The addition of the biocompatible membrane solution can prevent interference from other ions, thereby improving the anti-interference and selectivity of the fiber-based organic photoelectrochemical transistor uricase sensor.

[0041] In some specific embodiments, in step S1, the conductive fiber includes one of carbon fiber, metal fiber, or chemical fiber woven with a conductive medium.

[0042] In some specific embodiments, in step S2, the biocompatible membrane solution is a perfluorosulfonic acid polymer solution (Nafion solution).

[0043] In some specific embodiments, in step S3, the fiber with attached semiconductor material includes one of the following: fiber loaded with PEDOT:PSS, polyaniline (PANI), polypyrrole (PPy), and polythiophene (PEDOT) composite conductive fiber formed by in-situ polymerization.

[0044] In some specific embodiments, in step S1, the surface treatment step is as follows: the fiber to be treated is placed in deionized water, anhydrous ethanol and acetone solution in sequence, and ultrasonically cleaned for 10-20 minutes in each solution, then taken out and dried to obtain a clean fiber surface; in step S2, the surface treatment is to clean the Fe-MOF@PANI composite conductive fiber in sequence with anhydrous ethanol and organic solvent of the same type as those in the mixed solution to remove unreacted impurities.

[0045] A fiber-based organic photoelectrochemical transistor (OPT) uric acid sensor is prepared using the aforementioned method. This sensor uses fiber as a substrate and detects uric acid by regulating the gate voltage and the chemical reaction between the Fe-MOF@PANI material on the gate and uric acid oxidase, thereby altering the channel current. It should be noted that this OPT uric acid sensor is applied under illumination. Under illumination, the photosensitive material allows electrons to transition to the electrode surface, enabling the gate to regulate the channel current and synergistically detecting uric acid with the uric acid oxidase.

[0046] A fiber-based organic photoelectrochemical transistor uric acid sensor detects uric acid in real time under illumination by monitoring current. The uric acid concentration is quantitatively determined based on the current intensity. The sensor has a detection range of 1 nM to 10 mM, a detection limit of 1 nM, and a response time of 50 s, overcoming the limitations of traditional sensors such as long response time, high concentration requirements, and only qualitative detection capabilities. This uric acid sensor uses fiber as the substrate for the sensor electrode, combining the excellent flexibility of fiber with the electrode, making it applicable to flexible electronics. Furthermore, the fabrication method is simple and controllable, and the materials are readily available. The fabricated fiber-based organic photoelectrochemical transistor uric acid sensor achieves specific detection of uric acid and has promising application prospects.

[0047] Example 1

[0048] This embodiment provides a method for preparing a fiber-based organic photoelectrochemical transistor uric acid sensor, including the following steps:

[0049] S1. The carbon fiber was placed in deionized water, anhydrous ethanol and acetone solutions in sequence, and ultrasonically cleaned for 15 minutes in each solution. After being taken out and dried, the fiber with a clean surface was obtained.

[0050] S2. Take 15 mM 2-aminoterephthalic acid and 7.5 mM ferric chloride hexahydrate and put them into the reaction vessel for later use. Then take 10 mM aniline monomer and acetic acid and put them into the above reaction vessel together. Finally, add DMF as a solvent. Place the carbon fiber treated in step S1 into the reaction vessel and react at 150°C for 12 hours to obtain Fe-MOF@PANI composite conductive fiber.

[0051] S3. The Fe-MOF@PANI composite conductive fibers obtained in step S2 are cleaned with anhydrous ethanol and DMF respectively, and then placed in 10 mg / ml uric acid oxidase solution and soaked at 2°C for 24 h. After removal, they are air-dried at 2°C. Then they are soaked in 20% Nafion solution for 4 h and then air-dried at 2°C to serve as the gate of the organic photoelectrochemical transistor uric acid sensor.

[0052] S4. Take another fiber with PEDOT:PSS attached as the source and drain of the organic photoelectrochemical transistor uric acid sensor, and place it parallel to the gate of step S3 at a certain distance. Add gel electrolyte to coat the two fibers to obtain the fiber-based organic photoelectrochemical transistor uric acid sensor.

[0053] Please refer to Figure 1. The fiber-based organic photoelectrochemical transistor uric acid sensor prepared in Example 1 was used to detect different uric acid concentrations (1 nM, 10 nM, 1 μM, 10 μM, 1 mM, 5 mM) under illumination. The detection results are as follows. Figure 1 As shown in the figure, the fiber-based organic photoelectrochemical transistor uric acid sensor responds to the above-mentioned uric acid concentration, and the detection time is short, with a response occurring after 50 seconds. Therefore, the detection range of this uric acid sensor is 1 nM to 10 mM, and the detection limit is 1 nM.

[0054] Please see Figure 4 As shown, the fiber-based organic photoelectrochemical transistor uric acid sensor prepared in Example 1 was used to detect solutions containing 1 μM of different substances (DA-dopamine, Glu-glucose, Urea-urea, UA-urate, LA-lactic acid) under illumination. The results are as follows. Figure 4 As shown in the figure, the sensor exhibits good responsiveness only to uric acid solutions and strong anti-interference capabilities, indicating that in practical applications, it can eliminate interference from other substances in the human body, resulting in highly accurate detection results.

[0055] Comparative Example 1

[0056] Comparative Example 1 provides a method for preparing a fiber-based organic photoelectrochemical transistor uric acid sensor. The difference from Example 1 is that aniline monomer is not added in step S2. The rest is roughly the same as Example 1 and will not be repeated here.

[0057] Comparative Example 2

[0058] Comparative Example 2 provides a method for preparing a fiber-based organic photoelectrochemical transistor uric acid sensor. The difference from Example 1 is that 2-aminoterephthalic acid was not added in step S2. The rest is roughly the same as Example 1 and will not be repeated here.

[0059] Please see Figure 2 The image shows electron microscope (EM) images of the gate of the uric acid sensor prepared by the fiber-based organic photoelectrochemical transistor in Examples 1 and Comparative Examples 1-2; where (a) is carbon fiber, (b) is Comparative Example 1, (c) is Comparative Example 2, and (d) is Example 1. As can be seen from Figure (b), without the addition of aniline monomer, the Fe-MOF structure formed on the carbon fiber surface has poor uniformity and uneven distribution; while in Example 1, under the synergistic effect of aniline and Fe-MOF, a uniformly distributed, structurally regular, and dense Fe-MOF@PANI is formed on the carbon fiber surface.

[0060] Please see Figure 3 As shown in the figure, the fiber-based organic photoelectrochemical transistor uric acid sensors prepared in Example 1 and Comparative Examples 1-2 were used to detect uric acid of the same concentration, and the results are shown in the figure. It can be seen from the figure that the response time when Fe-MOF@PANI is used as the electrode is faster and the current change is larger than when Fe-MOF and PANI are used as electrodes alone. This is because Fe-MOF mainly absorbs light in the ultraviolet region, and the addition of PANI synergizes with the light absorption effect of Fe-MOF, increasing the sensor's absorption of visible light.

[0061] Examples 2-9 and Comparative Examples 3-8

[0062] Examples 2-9 and Comparative Examples 3-8 provide a method for preparing a fiber-based organic photoelectrochemical transistor uric acid sensor. Compared with Example 1, the differences are in the molar concentration of aniline monomer, the reaction temperature and reaction time settings in step S2, as shown in the table below. The rest are roughly the same as in Example 1 and will not be repeated here.

[0063] Table 1. Preparation parameters of Examples 2-9 and Comparative Examples 3-8

[0064]

[0065]

[0066] The fiber-based organic photoelectrochemical transistor uric acid sensors prepared in Examples 2-9 and Comparative Examples 3-8 were used to detect uric acid of the same concentration under light irradiation conditions. The results are shown in the table below.

[0067] Table 2. Detection results of uric acid sensors in Examples 2-9 and Comparative Examples 3-8.

[0068]

[0069] As shown in Table 2, Examples 2-4 and Comparative Examples 3 and 4, the initial current value and response time between the source and drain electrodes increase with the increase of the amount of aniline monomer. Decreasing the amount of aniline monomer increases the response time and decreases the initial current value between the source and drain electrodes. However, when the amount of aniline monomer is too large, it has a masking effect on the Fe-MOF, affecting the absorption of light by the Fe-MOF and reducing the change in current between the source and drain electrodes. As shown in Examples 5-7 and Comparative Examples 5 and 6, the initial current of the source and drain electrodes and the change in current between the source and drain electrodes increase with increasing temperature within the range of 100-150°C, while the response time decreases with increasing temperature within the same range. However, within the range of 150-220°C, the initial current of the source and drain electrodes and the change in current between the source and drain electrodes decrease with increasing temperature, while the response time increases with increasing temperature. This is because temperature affects the crystal size and grain distribution of the Fe-MOF, further affecting its absorption of light. As can be seen from Examples 8 and 9 and Comparative Examples 7 and 8, the hydrothermal reaction time also affects the initial source-drain current value, response time, and the change in source-drain current under illumination. This is because the reaction time affects the particle size of the Fe-MOF crystal.

[0070] In summary, this invention provides a fiber-based organic photoelectrochemical transistor uric acid sensor and its preparation method. The sensor is assembled by growing Fe-MOF@PANI on the surface of conductive fibers, modifying it with uric acid oxidase and a biocompatible membrane solution as the gate of the transistor, using fibers loaded with semiconductor materials as the source and drain electrodes of the photoelectrochemical transistor, and adding a gel electrolyte. This organic photoelectrochemical transistor uric acid sensor uses a fiber substrate as the electrode, with photosensitive materials and sensing substances modified on the gate. The photosensitive material allows electrons to jump to the electrode surface under illumination, enabling regulation of the channel current and, in conjunction with the sensing substance, achieving uric acid detection. Under illumination, the fiber-based organic photoelectrochemical transistor uric acid sensor detects uric acid by real-time detection of the current; and by reflecting the uric acid concentration based on the current intensity, it achieves quantitative detection. Its uric acid concentration detection range is 1 nM to 10 mM, with a detection limit of 1 nM and a detection response time of 50 s, overcoming the shortcomings of traditional sensors such as long response time, high concentration requirements for uric acid, and only qualitative detection. Furthermore, this uric acid sensor improves the sensitivity of uric acid detection while operating under zero grid bias, which not only simplifies the sensor structure but also reduces background signals and interference, thus exhibiting good current response to different concentrations of uric acid and possessing great market potential.

[0071] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a fiber-based organic photoelectrochemical transistor uric acid sensor, characterized in that, Includes the following steps: S1. Surface-treat the conductive fibers, place them in a reaction vessel containing a mixed solution, and control the reaction temperature and time to prepare Fe-MOF@PANI composite conductive fibers; the mixed solution includes a complexing agent, an iron salt solution, an organic solvent, a dopant, and an aniline monomer; S2. The Fe-MOF@PANI composite conductive fiber obtained in step S1 is surface treated, placed in a uric acid oxidase solution, and soaked at 2-4°C for 22-26 hours. After removal, it is air-dried naturally. Then, it is placed in a biocompatible membrane solution and soaked for 3-5 hours. After removal, it is air-dried naturally and used as the gate of the organic photoelectrochemical transistor uric acid sensor. The air-drying temperature for both steps is 2-4°C. S3. Use the fiber with attached semiconductor material as the source and drain of the organic photochemical transistor uric acid sensor, and place it parallel to the gate of step S2 at a certain distance. Add gel electrolyte to obtain the fiber-based organic photochemical transistor uric acid sensor. In step S1, the molar concentration ratio of the complexing agent to the aniline monomer is (0.5-2):1; the molar concentration ratio of the complexing agent to the iron salt solution is (1.6-2.4):

1. In step S1, the complexing agent is 2-aminoterephthalic acid; the iron salt solution includes one of ferric chloride hexahydrate, ferric chloride, ferric nitrate nonahydrate, and ferric sulfide. In step S1, the dopant includes one of acetic acid, hypochlorous acid, hydrofluoric acid, and carbonic acid; the organic solvent includes any one of N,N-dimethylformamide, dimethylacetamide, dimethylpropionamide, diethylformamide, or diethylacetamide.

2. The method for preparing the fiber-based organic photoelectrochemical transistor uric acid sensor according to claim 1, characterized in that, In step S1, the reaction temperature is 120–200°C and the reaction time is 8–24 hours.

3. The method for preparing the fiber-based organic photoelectrochemical transistor uric acid sensor according to claim 1, characterized in that, In step S2, the concentration of the uricase is 5–15 mg / ml, and the concentration of the biocompatible membrane solution is 5%–25%.

4. The method for preparing the fiber-based organic photoelectrochemical transistor uric acid sensor according to claim 1, characterized in that, In step S1, the conductive fiber includes one of carbon fiber, metal fiber, or chemical fiber woven with a conductive medium; in step S2, the biocompatible membrane solution is a perfluorosulfonic acid type polymer solution; in step S3, the fiber with attached semiconductor material includes one of fiber loaded with PEDOT:PSS, polyaniline, polypyrrole, or polythiophene composite conductive fiber formed by in-situ polymerization.

5. The method for preparing the fiber-based organic photoelectrochemical transistor uric acid sensor according to claim 1, characterized in that, In step S1, the surface treatment step is as follows: the fiber to be treated is placed in deionized water, anhydrous ethanol and acetone solution in sequence, and ultrasonically cleaned for 10-20 minutes in each solution. After cleaning, the fiber is taken out and dried to obtain a clean fiber. In step S2, the surface treatment is to clean the Fe-MOF@PANI composite conductive fiber in sequence with anhydrous ethanol and organic solvent of the same type as the mixed solution to remove unreacted impurities.

6. A fiber-based organic photoelectrochemical transistor uric acid sensor, characterized in that, The uric acid sensor is prepared by the method described in any one of claims 1 to 5. The uric acid sensor uses fiber as a substrate and detects uric acid by adjusting the gate voltage and the chemical reaction between the Fe-MOF@PANI material on the gate and uric acid oxidase, thereby changing the channel current.

7. The fiber-based organic photoelectrochemical transistor uric acid sensor according to claim 6, characterized in that, The fiber-based organic photoelectrochemical transistor uric acid sensor has a uric acid concentration detection range of 1 nM to 10 mM, a detection limit of 1 nM, and a response time of 50 s.

Images