Bimetallic-mof-based dual-mode sensing material and preparation method and application thereof

Abstract

The application relates to the technical field of sensing detection, and provides a dual-mode sensing material based on a bimetallic MOF, a preparation method of the dual-mode sensing material and application of the dual-mode sensing material in detection of cysteine. The dual-mode sensing material based on the bimetallic MOF is prepared by using a flexible conductive fiber as a base material, and a bimetallic MOF is synthesized on the surface of the base material by a hydrothermal method. The dual-mode sensing material has a unique heterostructure and a high specific surface area, can specifically recognize and capture cysteine, can cause a ligand-metal charge transfer effect, and can realize fluorescence signal enhancement. Meanwhile, the introduction of the cysteine into a detection system can significantly change the electronic structure and the conductivity of the MOF, and further cause a synergistic weakening of a current signal. The application realizes high-sensitivity and high-selectivity detection of the cysteine by integrating two detection modes of fluorescence and electrochemistry, has the outstanding advantages of fast response speed, low detection limit, strong anti-interference capability and portability, and shows a broad application prospect in the fields of biomedical diagnosis, food safety analysis and environmental monitoring.

Description

Technical Field

[0001] This invention relates to the field of sensing and detection technology, specifically to a dual-mode sensing material based on bimetallic MOFs, its preparation method, and its application in detecting cysteine. Background Technology

[0002] L-cysteine ​​is a conditionally essential amino acid containing a sulfhydryl group (-SH). Abnormal concentrations of L-cysteine ​​in the body are closely related to various diseases. For example, elevated serum L-cysteine ​​levels are an important risk marker for cardiovascular disease and Alzheimer's disease, while decreased L-cysteine ​​concentrations may be associated with liver damage, tumor progression, and congenital metabolic disorders. Furthermore, in the food industry, L-cysteine ​​is commonly used as a dough improver and antioxidant preservative, and its content directly affects food quality and safety. In addition, accurate detection of L-cysteine ​​in biological fluids and food samples not only provides important molecular diagnostic evidence for early disease screening and disease progression monitoring, but also ensures the quality controllability of food and pharmaceutical products, possessing irreplaceable practical significance for clinical medicine, public health, and industrial production.

[0003] Currently, common methods for detecting cysteine ​​include high-performance liquid chromatography (HPLC) and enzyme-linked immunosorbent assay (ELISA). HPLC has drawbacks such as high requirements for instruments and techniques, and long detection time; ELISA has drawbacks such as lower detection accuracy and its accuracy being easily affected by factors such as antibody quality and cross-reactivity.

[0004] Existing technical document CN119350638A also discloses a bimetallic organic framework capable of recognizing cysteine ​​and its preparation method. The bimetallic organic framework material is prepared by heating hypoxanthine with 1,3,5-benzenetricarboxylic acid, zinc ions, cobalt ions, and HNO3 in a polytetrafluoroethylene high-pressure reactor at 140°C for 72 hours. In this framework, Co... 2+ and Co 3+ Partially replaced Zn at the metal sites 2+ This enhances the functionality of the active metal center, and the specific pore shape and size significantly enhance the detection signal for cysteine. However, this bimetallic organic framework material requires a solvothermal reaction time of up to 3 days, resulting in a long preparation cycle. Furthermore, the cysteine ​​solution needs to be stored in the dark for 3 days for detection. Although the color change of the solution from colorless to yellow and the change of the MOF crystals from dark purple to light purple are visually identifiable, the detailed detection cycle remains excessively long. Summary of the Invention

[0005] Therefore, it is necessary to provide a dual-mode sensing material based on bimetallic MOFs, its preparation method, and its application in detecting cysteine. The preparation cycle is shortened and it can achieve both electrochemical and fluorescence responses to cysteine, with high detection sensitivity, fast response, and good stability.

[0006] The present invention adopts the following technical solution: This invention provides a dual-mode sensing material based on bimetallic MOF, comprising a conductive fiber substrate and a MOF particle layer uniformly composited on the conductive fiber substrate; the MOF particle layer is mainly prepared by hydrothermal reaction of metal salt, 2-aminoterephthalic acid, N,N-dimethylformamide and deionized water, wherein the metal salt is selected from zinc salt and nickel salt.

[0007] In some embodiments, the molar ratio of the two metal salts to 2-aminoterephthalic acid is (1~3):(1~3):1.

[0008] In some embodiments, the conductive fiber substrate is selected from at least one of carbon fiber, metal fiber, conductive metal compound fiber, and conductive polymer fiber.

[0009] In some of these embodiments, the MOF particle size is 1~2µm.

[0010] This invention provides a method for preparing a dual-mode sensing material based on a bimetallic MOF, comprising the following steps: mixing a metal salt as a precursor, 2-aminoterephthalic acid as a ligand, N,N-dimethylformamide, and deionized water, followed by ultrasonic treatment to obtain a mixed solution containing the precursor and ligand; subjecting a pretreated conductive fiber substrate (after cleaning and drying) to a hydrothermal reaction with the mixed solution containing the precursor and ligand, followed by cooling, cleaning, and drying to obtain the final product.

[0011] Preferably, the metal salt is selected from zinc salt and nickel salt, and the molar ratio of zinc salt, nickel salt and 2-aminoterephthalic acid is 2:1:1.

[0012] Preferably, the parameters for the hydrothermal reaction are: temperature 140~150℃, duration 12h.

[0013] Preferably, the volume ratio of N,N-dimethylformamide to deionized water is (1~3):1.

[0014] Preferably, the concentration of the metal salt in the mixed solution containing the precursor and ligand is 0.001~0.003 mol / L.

[0015] Preferably, the parameters for the ultrasonic treatment are: power 100~300W, duration 10~30min.

[0016] Preferably, the cleaning process uses N,N-dimethylformamide and ethanol.

[0017] This invention provides the application of a bimetallic MOF-based dual-mode sensing material in the detection of cysteine-containing samples.

[0018] This invention relates to the application of bimetallic MOF-based flexible fiber-based dual-mode sensing materials in the fields of smart wearables and smart anti-counterfeiting. The MOF powder can be made into photoluminescent ink, which can be used to write on paper. The writing is not visible under sunlight, but can be seen under ultraviolet light. The flexible fiber base can be reacted with cotton thread, and the resulting cotton thread can be used for weaving, or it can be wet-spun to obtain fibers, dried, and then woven into desired patterns or electrospun into films.

[0019] Compared with existing technologies, the core technical advantages and beneficial effects of this invention are as follows: This invention uses two metal salts as precursors and 2-aminoterephthalic acid as ligand to synthesize a uniformly distributed bimetallic MOF on the surface of conductive fibers using a hydrothermal method. As a dual-mode sensing material and device, it can achieve dual fluorescence and current response to cysteine, with high sensitivity and low detection limit, and the fluorescence intensity change can be observed with the naked eye.

[0020] This invention relates to a method for preparing flexible fiber-based dual-mode sensing materials based on bimetallic MOFs. By controlling the molar ratio of precursors and ligands and reaction parameters, the uniformity and particle size of the organometallic framework particles distributed on the surface of conductive fibers can be effectively controlled. This allows the organometallic framework particles to be tightly bonded to the fiber substrate, thereby effectively controlling the luminescence intensity and stability of the fibers. As a result, the fiber-based dual-mode sensor device exhibits good flexibility, fast response time, excellent fluorescence stability, and sensitive sensing characteristics, showing promising application prospects in the fields of smart wearables and visual smart sensing.

[0021] Compared to the scheme disclosed in existing technical document CN119350638A, this invention, when detecting cysteine ​​samples, exhibits enhanced fluorescence intensity and a change in fluorescence color from blue to cyan-blue with increasing analyte concentration, which can be discerned visually under ultraviolet light. The fluorescence color change is more pronounced at mM concentrations. The current decreases systematically with increasing analyte concentration. The entire detection response is extremely fast, with significant fluorescence changes within 1 minute, eliminating the need for prolonged waiting. The flexible fiber-based dual-mode sensing material based on bimetallic MOFs is directly grown on the fiber substrate, eliminating the need for cumbersome steps such as weighing, sealing, and settling. Cysteine ​​analytes can be directly added for detection, truly facilitating portable and rapid sampling and detection. The detection range is broad, covering concentrations from μM to 1M, making it highly practical. Simultaneously, material preparation efficiency is significantly improved; the entire preparation process can be completed within one day, with a simpler procedure and no need for prolonged high-temperature reactions. Attached Figure Description

[0022] Figure 1 The image shows a scanning electron microscope (SEM) image of the carbon fiber substrate used in Example 1 after cleaning. The scale bar is 10 µm.

[0023] Figure 2 The image shows a scanning electron microscope (SEM) image of the flexible fiber-based dual-mode sensor based on a bimetallic MOF prepared in Example 1.

[0024] Figure 3 The fluorescence sensing image shows the application of the flexible fiber-based dual-mode sensor based on bimetallic MOF prepared in Example 1 to cysteine ​​detection.

[0025] Figure 4 This is a statistical graph showing the stability of fluorescence intensity in the detection of cysteine ​​by the flexible fiber-based dual-mode sensor based on bimetallic MOF prepared in Example 1.

[0026] Figure 5 The image shows the electrochemical sensing of the flexible fiber-based dual-mode sensor based on bimetallic MOF prepared in Example 1, applied to the detection of cysteine.

[0027] Figure 6 The flexible fiber-based dual-mode sensor of the bimetallic MOF prepared in Example 1 was used to detect the fluorescence sensing linear fitting relationship of different concentrations of cysteine ​​(L-cys).

[0028] Figure 7 The flexible fiber-based dual-mode sensor based on the bimetallic MOF prepared in Example 1 was used to perform current sensing linear fitting of different concentrations of cysteine.

[0029] Figure 8 The fluorescence comparison image shows the bimetallic MOF-based sensor prepared in Example 1 being used to detect different analytes (Tyr, Ile, Trp, glu, GSH, L-cys) at the same concentration.

[0030] Figure 9 The image shows the fluorescence changes of a cotton thread after different concentrations of L-cysteine ​​were applied to a bimetallic MOF-based sensor prepared in Example 1.

[0031] Figure 10 The images show the blue light emitted by the bimetallic MOF powder prepared in Example 1 under a UV lamp and the UV lamp irradiation of the MOF powder attached to the carbon fiber after adding 100 mM L-cys. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to specific embodiments, so that those skilled in the art can more clearly understand the present invention. The following embodiments are only used to illustrate the present invention, and are not intended to limit the scope of the present invention. Based on the specific embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention. In the embodiments of the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art; in the embodiments of the present invention, unless specifically specified, the technical means used are conventional means well known to those skilled in the art.

[0033] Key experimental materials sources and physicochemical properties: Zinc chloride: purchased from Macklin, physicochemical properties: purity ≥98.0%.

[0034] Nickel chloride hexahydrate, purchased from Macklin, physicochemical properties: purity ≥98.0%.

[0035] 2-Aminoterephthalic acid, purchased from Macklin, physicochemical properties: purity ≥98.0%.

[0036] Carbon fiber: purchased from Sinopharm Chemical Reagent Co., Ltd., physicochemical properties: average fiber diameter is approximately 5μm.

[0037] Metal fibers: purchased from Nanjing Xianfeng Nanomaterials Technology Co., Ltd., with physical and chemical properties: fiber diameter 1–10 μm and purity ≥99.0%.

[0038] Conductive metal compound fiber: purchased from Suzhou Youzirconium Nanomaterials Co., Ltd., physicochemical properties: volume resistivity ≤10. -3 Ω・cm, fiber diameter 2–8 μm.

[0039] Conductive polymer fiber: purchased from Shanghai Maclean Biochemical Technology Co., Ltd., physicochemical properties: volume resistivity ≤10. -2 Ω・cm, fiber diameter 3–10 μm.

[0040] Additionally, it is worth noting the evaluation criteria for sensing performance in this invention: (1) Good: When different concentrations of the analyte are added, the detected fluorescence intensity and current change regularly, the fitting relationship is good, the fluorescence changes are obvious to the naked eye, and the fluorescence increases with the increase of the concentration of the analyte.

[0041] (2) Medium: When different concentrations of the analyte are added, the detected fluorescence intensity and current change but there is no regularity. The fluorescence changes slightly with the increase of the concentration of the analyte, but the change is not significant.

[0042] (3) Generally: When different concentrations of the analyte are added, the fluorescence intensity and current of the detection change slightly, but the fluorescence and current changes little with different concentrations.

[0043] (4) Poor: When different concentrations of the analyte are added, the detected fluorescence intensity and current hardly change.

[0044] Evaluation criteria for fluorescence performance: (1) Good: When the target product is detected, the entire fiber can emit light, and the light emission is uniform and obvious.

[0045] (2) Medium: When the target product is detected, the light emission is obvious, and the entire fiber is basically luminescent with no obvious non-luminescent areas.

[0046] (3) General: When detecting the target product, the luminescence is not very obvious, and only some parts of a fiber may emit light.

[0047] (4) Poor: When detecting the target product, only a few spots emit light, and some spots do not emit light at all.

[0048] Evaluation criteria for uniformity of bimetallic MOFs: (1) Good: The bimetallic MOF is evenly distributed on the fiber, and the entire fiber is densely covered.

[0049] (2) Medium: Bimetallic MOFs are distributed relatively evenly on the fiber, and are attached to all positions, but may not grow much in some places.

[0050] (3) Generally: Bimetallic MOFs are unevenly distributed on fibers, or they grow very large in some places but are not tightly attached and are easy to fall off. They are not present in every location, and some places are not covered.

[0051] (4) Poor: Most fibers did not grow bimetallic MOFs, and the fibers were still very clean, with only a few sporadic attachments in some places.

[0052] The following example illustrates this.

[0053] Example 1 This embodiment provides a method for preparing bimetallic MOF composite fibers and their application as flexible fiber-based dual-mode sensors.

[0054] The preparation method of bimetallic MOF composite fibers in this embodiment includes the following steps: S1, prepare a mixed solution containing precursor and ligand.

[0055] Weigh out 0.2 mmol of zinc chloride, 0.1 mmol of nickel chloride hexahydrate and 0.1 mmol of 2-aminoterephthalic acid, respectively, and add them to a mixed solvent of 10 mL of N,N-dimethylformamide and 5 mL of deionized water. Sonicate at 300 W for 30 min to obtain a mixed solution containing the precursor and ligand.

[0056] S2, hydrothermal reaction to prepare bimetallic MOF-based composite fibers.

[0057] Carbon fibers were ultrasonically cleaned in deionized water and ethanol for 30 min in sequence, and then dried to obtain pretreated carbon fiber substrate. The mixed solution containing precursor and ligand prepared in step S1 was transferred to a polytetrafluoroethylene liner, and the pretreated carbon fiber substrate (size: 5 μm) was placed in the aforementioned mixed solution. The substrate was hydrothermally reacted at 150 °C for 12 h, cooled to room temperature, removed, and cleaned in sequence with DMF and ethanol. The substrate was then air-dried to obtain bimetallic MOF composite fiber (ZnNi-MOF composite fiber).

[0058] The pretreated carbon fiber substrate and the bimetallic MOF composite fiber (ZnNi-MOF composite fiber) of this embodiment were structurally characterized, respectively. The results are as follows: Figure 1 and Figure 2 As shown.

[0059] from Figure 1 As can be seen, the surface of the pretreated carbon fiber substrate is smooth after cleaning.

[0060] from Figure 2 As can be seen, after the hydrothermal reaction, a thick layer of ZnNi-MOF particles with a diameter of about 1~2 µm was densely grown on the surface of the pretreated carbon fiber.

[0061] This embodiment uses bimetallic MOF composite fiber (ZnNi-MOF composite fiber) as a flexible fiber-based dual-mode sensor to detect cysteine. The specific steps are as follows: A 1 mol / L cysteine ​​solution is prepared and diluted with deionized water to concentrations of 100 mmol / L, 10 mmol / L, 1 mmol / L, 100 µmol / L, 10 µmol / L, 1 µmol / L, 100 nmol / L, 10 nmol / L, and 1 nmol / L. The cysteine ​​solutions of different concentrations are then added dropwise to the fiber with the bimetallic MOF growth, and fluorescence and electrochemical detection are performed.

[0062] Fluorescence detection: The change in fluorescence intensity was measured using a fluorescence spectrophotometer, and the fluorescence change was observed with the naked eye under a UV lamp.

[0063] Electrochemical detection: The current change is measured using a semiconductor analyzer using the differential pulse method to determine the quality of the sensing performance.

[0064] The statistical results of the fluorescence sensing examination are as follows: Figure 3 As shown, this embodiment uses bimetallic MOF composite fiber (ZnNi-MOF composite fiber) as a sensor device, which has a significant fluorescence response to the above-mentioned different concentrations of cysteine.

[0065] The stability test results of fluorescence intensity of ZnNi-MOF composite fibers prepared from different batches of the same sample are as follows: Figure 4 As shown, the fluorescence intensity values ​​of different devices do not change significantly, indicating that the fabricated flexible fiber-based dual-mode sensor based on bimetallic MOF has good fluorescence stability.

[0066] Electrochemical test results as follows Figure 5 As shown, this embodiment, based on bimetallic MOF composite fiber (ZnNi-MOF composite fiber) as a sensor device, exhibits a significant current response to the above-mentioned different concentrations of cysteine, demonstrating good electrochemical detection performance.

[0067] A fluorescence spectrophotometer with a 10 nm slit and an excitation wavelength of 370 nm was used to excite the sample. The fluorescence intensity was measured without the analyte and with different concentrations of the analyte added. The fluorescence intensity without the analyte was taken as F0, and the fluorescence intensity after the analyte was added was taken as F.

[0068] Using Origin software, a scatter plot was created with the analyte concentration on the x-axis and (F-F0) / F0 (the ratio of the difference between the original fluorescence value and the original fluorescence value after adding different concentrations of analyte) on the y-axis. The plot was then linearly fitted to obtain the following results: Figure 6 The fitted curve.

[0069] Electrochemical measurements were performed using a three-electrode system with KCl and potassium ferricyanide electrolytes. The redox peak position was located using cyclic voltammetry with a semiconductor analyzer. The voltage at the redox peak position was set to the voltage range of differential pulse voltammetry. The current values ​​were measured with and without the addition of different concentrations of the analyte. It was found that the current gradually decreased with increasing concentration.

[0070] Using Origin plotting software, the concentration of the analyte was plotted on the x-axis, the current without analyte addition was plotted as the initial current I0, and the ratio of the current difference before and after addition to the initial current was plotted on the y-axis. A linear fit was then performed on the data to obtain... Figure 7 The fitted curve.

[0071] This indicates that the concentration range for electrochemical detection of cysteine ​​is 1 μM to 100 μM, while the concentration range for fluorescence detection of cysteine ​​is 1 μM to 1 M.

[0072] Further, cut filter paper pieces were added to the solution after dissolving and dispersing the bimetallic MOF powder. The mixture was soaked for several hours to ensure the MOF was evenly coated on the filter paper. After drying in an oven, filter paper pieces coated with MOF were added to the analytes (Tyr, Ile, Trp, glu, GSH, L-cys). The photographs show that only L-cys emitted the strongest and most uniform fluorescence. The results are as follows... Figure 8 As shown.

[0073] Similarly, after soaking cotton fibers containing MOF, the fluorescence of different concentrations of the analyte L-cys changed, showing that the fluorescence became stronger with increasing concentration, and the fluorescence color changed from blue to cyan-blue, as shown in the results. Figure 9 As shown.

[0074] The bimetallic MOF powder prepared in Example 1 emitted blue light under ultraviolet light. The MOF powder attached to carbon fibers, after being irradiated with 100 mM L-cys, exhibited significant fluorescence under ultraviolet light. The results are as follows... Figure 10 As shown.

[0075] Comparative Example 1 Comparative Example 1 provides a method for preparing bimetallic MOF composite fibers, the steps of which are basically the same as those in Example 1, except that the carbon fiber surface is not pretreated.

[0076] The experimental results showed that the number of MOF particles grown from carbon fiber composites without surface pretreatment was small, making further application testing impossible.

[0077] Comparative Example 2 Comparative Example 2 provides a method for preparing bimetallic MOF composite fibers. The method steps are basically the same as those in Example 1, except that in step S1, the mixed solution of solvent N,N-dimethylformamide and deionized water is replaced with deionized water.

[0078] The test results showed that the surface of the pretreated carbon fiber had almost no particles, making it unsuitable for further application testing.

[0079] Comparative Example 3 Comparative Example 2 provides a method for preparing bimetallic MOF composite fibers. The method steps are basically the same as those in Example 1, except that in step S1, ultrasonic treatment was not performed when preparing the mixed solution containing the precursor and ligand.

[0080] The experimental results showed that the MOF growth on the carbon fiber surface was uneven after pretreatment.

[0081] Example 2 Referring to the preparation method of bimetallic MOF composite fibers and the application method of using them as flexible fiber-based dual-mode sensors to detect cysteine ​​in Example 1, this example explores the performance comparison of products prepared from different conductive fibers.

[0082] The types of conductive fibers, product characterization, and performance test results are shown in the table below: As can be seen from the table above, all four types of conductive fibers can achieve the bimetallic MOF composite effect.

[0083] Example 3 Referring to the preparation method of metal MOF composite fibers and the application method of using them as flexible fiber-based dual-mode sensors to detect cysteine ​​in Example 1, this example explores the performance comparison of products prepared with different molar ratios of metal salts.

[0084] The experimental molar ratios of metal salts and the results of product characterization and performance testing are shown in the table below: As can be seen from the table above: When the molar ratio of zinc salt and nickel salt in a metal salt is different, it will affect the distribution uniformity and particle size of MOF particles, thus affecting the fluorescence performance.

[0085] Example 4 Referring to the preparation method of metal MOF composite fibers and the application method of using them as flexible fiber-based dual-mode sensors to detect cysteine ​​in Example 1, this example explores the performance comparison of products prepared under different hydrothermal reaction conditions.

[0086] The experimental hydrothermal reaction conditions, product characterization, and performance test results are shown in the table below: As can be seen from the table above: Hydrothermal reaction conditions have a significant impact on the distribution and particle size of MOF particles on carbon fiber substrates, thus affecting fluorescence sensing performance.

[0087] Example 5 Referring to the preparation method of metal MOF composite fibers and the application method of using them as flexible fiber-based dual-mode sensors to detect cysteine ​​in Example 1, this example explores the performance comparison of products prepared under ultrasonic conditions.

[0088] The ultrasonic time conditions, product characterization, and performance test results are shown in the table below: Example 6 Referring to the preparation method of metal MOF composite fibers and the application method of using them as flexible fiber-based dual-mode sensors to detect cysteine ​​in Example 1, this example explores the performance comparison of products prepared by replacing nickel chloride with different types of metal salts (chlorides) in equal molar amounts.

[0089] The metal salt types, product characterization, and performance test results are shown in the table below: As can be seen from the table above: MOF composite fibers prepared using ZnNi bimetallic salts exhibit superior overall performance.

[0090] Not limited to the above experimental examples, this invention has discovered through extensive experimental research that: (1) Using conductive fibers as substrate, preferably using hydrothermal method to grow regular bimetallic MOF particles on its surface, can achieve significant fluorescence and electrochemical response to cysteine.

[0091] (2) Zinc chloride and nickel chloride metal salt are preferred to be combined. N,N-dimethylformamide and deionized water are preferred as a mixed solvent. After ultrasonic treatment, hydrothermal reaction is carried out. The reaction temperature is preferably 140~150℃ and the reaction time is about 12h. This can obtain bimetallic MOF particles with uniform surface growth.

[0092] (3) The dual-mode sensor based on ZnNi-MOF flexible fiber has good flexibility, excellent electrochemical fluorescence dual-mode sensing performance, and high sensitivity, with superior overall performance.

[0093] It should be noted that the above embodiments are only for further elaboration and explanation of the technical solution of the present invention, and are not intended to further limit the technical solution of the present invention. The method of the present invention is only a preferred embodiment and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A dual-mode sensing material based on a bimetallic MOF, characterized in that, It comprises a conductive fiber substrate and a MOF particle layer uniformly composited on the conductive fiber substrate; The MOF particle layer is mainly prepared by hydrothermal reaction of metal salt, 2-aminoterephthalic acid, N,N-dimethylformamide and deionized water, wherein the metal salt is selected from zinc salt and nickel salt.

2. The dual-mode sensing material based on bimetallic MOF according to claim 1, characterized in that, The conductive fiber substrate is selected from at least one of carbon fiber, metal fiber, conductive metal compound fiber, and conductive polymer fiber.

3. The dual-mode sensing material based on a bimetallic MOF according to claim 1 or 2, characterized in that, MOF particles have a diameter of 1~2µm.

4. The method for preparing the dual-mode sensing material based on bimetallic MOFs according to any one of claims 1 to 3, characterized in that, Includes the following steps: A metal salt was used as a precursor, 2-aminoterephthalic acid was used as a ligand, and N,N-dimethylformamide and deionized water were mixed and ultrasonically treated to obtain a mixed solution containing the precursor and ligand. The conductive fiber substrate, after being cleaned and dried, is subjected to a hydrothermal reaction with a mixed solution containing precursors and ligands at a temperature of 140~150℃ for 12 hours. After cooling, cleaning, and drying, the product is obtained.

5. The method for preparing a dual-mode sensing material based on a bimetallic MOF according to claim 4, characterized in that, The metal salt is selected from zinc salt and nickel salt, and the molar ratio of zinc salt, nickel salt and 2-aminoterephthalic acid is 2:1:

1.

6. The method for preparing a dual-mode sensing material based on a bimetallic MOF according to claim 4 or 5, characterized in that, The parameters for the hydrothermal reaction are: temperature 140~150℃, duration 12~18h.

7. The method for preparing a dual-mode sensing material based on a bimetallic MOF according to claim 4 or 5, characterized in that, The volume ratio of N,N-dimethylformamide to deionized water is (1~3):

1.

8. The method for preparing a dual-mode sensing material based on a bimetallic MOF according to claim 4 or 5, characterized in that, The parameters for the ultrasonic treatment are: power 100~300W, duration 10~30min.

9. The method for preparing a dual-mode sensing material based on a bimetallic MOF according to claim 4 or 5, characterized in that, The cleaning process uses N,N-dimethylformamide and ethanol.

10. The application of the bimetallic MOF-based dual-mode sensing material as described in claim 1 or 2 in the detection of cysteine-containing samples, smart wearable products, and smart anti-counterfeiting products.

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