ZIF-8-centered electrochemical sensor for detecting ion content in urine, detection method and antibacterial catheter

Abstract

The invention belongs to the technical field of electrochemical sensors, and relates to an electrochemical sensor for detecting the ion content in urine by taking ZIF-8 as a center, a detection method and an antibacterial catheter. An electrode array is arranged in the electrochemical sensor and comprises a working electrode, a counter electrode and a reference electrode; the working electrode comprises a ZIF-8 modified carbon electrode, and the electrode is prepared by coating a flexible substrate containing a carbon electrode with turbid liquid containing a ZIF-8 composite porous sensitive material and then drying. The ZIF-8 composite porous sensitive material is prepared by in-situ synthesis on a polyvinyl chloride material containing hydroxyl or carboxyl through a one-step method. When the sensor is used for ion detection, the anti-interference performance is high, the sensitivity is high, the ion selectivity is high, and the concentration of ions such as K < + >, Na < + > and Cl <-> in urine can be monitored for a long time under soaking. When the catheter loaded with the sensor is used for urine drainage of a patient, ions in urine can be detected in real time, and the sensor has lasting antibacterial performance.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical sensor technology, and relates to an electrochemical sensor, detection method and antibacterial urinary catheter for detecting ion content in urine centered on ZIF-8. Background Technology

[0002] The concentration of certain compounds in urine can provide information about many different conditions, including kidney disease, urinary tract infections, and electrolyte deficiencies, thus reflecting a person's health status. 24-hour urinary potassium, sodium, and chloride levels can help doctors diagnose relevant diseases in patients and their potential causes, guiding appropriate treatment. Generally, the excretion of potassium, sodium, and chloride in urine varies considerably throughout the day; therefore, measuring these levels requires collecting a complete 24-hour urine sample. The normal reference values ​​for urinary potassium are 25-100 mmol / 24h, urinary sodium 130-260 mmol / 24h, and urinary chloride 170-250 mmol / 24h.

[0003] For example, the determination of potassium ions in urine is of great significance for the clinical diagnosis of uremia, acute intestinal obstruction, and adrenocortical insufficiency or hyperadrenocorticism. Patients who wish to undergo urine testing usually have to go through a hospital laboratory or use test strips themselves; however, the sensitivity of test strips is generally low, making rapid clinical diagnosis impossible. To overcome these limitations of test strip testing, various electrochemical sensing technologies have attracted considerable attention, becoming one of the most promising rapid detection methods due to their simplicity and speed. An electrochemical sensor is a sensor device that performs qualitative and quantitative analysis and measurement, converting the chemical quantity of the analyte into an electrical quantity for sensing and detection. The basic components of a typical electrochemical sensor are: a working (or sensing) electrode, a reference electrode, and usually a counter electrode. These electrodes are attached to the sensor and lined with an electrolyte. The electrodes are located on the inner surface of a diffusion membrane, which has pores allowing the analyte to pass through, but the electrolyte cannot permeate. After the analyte diffuses into the sensor and passes through the membrane to reach the electrode, an electrochemical reaction occurs, either oxidation or reduction, depending on the type of substance. Oxidation reactions cause electrons to flow from the working electrode to the counter electrode through the external circuit; conversely, reduction reactions cause electrons to flow from the counter electrode to the working electrode. These electron flows constitute an electric current, which is proportional to the gas concentration. The sensor module and internal instrument circuitry detect and amplify the current, ultimately measuring the type and concentration of the analyte and outputting the results.

[0004] Patent document CN110146577A discloses an electrochemical sensor and a method for monitoring potassium ions. The method involves ultrasonically dispersing 1-aza-18-crown-6 ether-functionalized graphene oxide (Crown-GO) in an aqueous solution to obtain a Crown-GO suspension. This Crown-GO suspension is then uniformly dropped onto the surface of a polished, cleaned, and dried glassy carbon electrode to obtain a Crown-GO / GCE working electrode. This method primarily uses graphene oxide to immobilize the potassium ion carrier, improving the adsorption capacity and binding selectivity of the material for potassium ions. However, the graphene oxide used in this method is prone to aggregation, reducing detection sensitivity. Although traditional sensors for ion assessment are widely used, they suffer from many limitations and obstacles in terms of sensitivity, selectivity, and simplicity. Against this backdrop, metal ions and metal-organic frameworks (MOFs) based on organic ligands have attracted widespread attention due to their advantages such as larger surface area, porosity, high sensitivity, and well-defined selectivity.

[0005] Patent document CN117030686A discloses a method for preparing an iodide ion electrochemiluminescence sensor. This method uses iodide ions as the target analyte, a zinc porphyrin complex as the electrochemiluminescent agent, and selects classic glutathione-stabilized silver nanoclusters (GSH-AgNCs) as a model. A composite nanomaterial (GSH-AgNCs@ZIF-8) constructed with imidazole MOF (ZIF-8) is then used as a catalyst to further construct the electrochemiluminescence sensor (ECL). This novel ECL system is simple in design, easy to use, and has minimal interference with analytes, achieving high-efficiency detection of iodides (I-) with a low detection limit. However, the preparation process is complex, undoubtedly increasing the difficulty for large-scale production.

[0006] Patent document CN110183674B discloses a method for preparing a sodium ion electrochemical sensor electrode material. This method produces a metal-organic framework (MOF) material with a dendritic self-similar fractal structure. The surface can be enriched and immobilized with a large number of hydrated sodium ions, and the small amount of hydrated sodium ions that can enter the pores can diffuse and distribute uniformly. This method solves the problem of synthesizing fractal structured MOF materials on substrates using conventional methods, and the entire process is simple, energy-efficient, and fast. However, the copper ions released by this MOF material have certain biotoxicity, making it difficult to integrate with implantable devices, such as urinary catheters, thus limiting its application in implantable devices.

[0007] Patent document CN114805912B discloses a method for preparing a MOF composite porous sensitive membrane for a potassium ion electrochemical sensor. First, K-MOF material is prepared. Then, appropriate amounts of K-MOF, polymer substrate material, ion support, and ion localization agent are dissolved together in a tetrahydrofuran solution. After thorough dissolution by magnetic stirring and ultrasonic vibration, the solution is poured onto a glass slide and dried at room temperature to obtain a MOF composite porous sensitive membrane. The composite porous sensitive membrane for the K+ electrochemical sensor prepared by this method has a short K+ recognition response time. Furthermore, the preparation method of this invention is simple, with a short process flow, effectively improving production efficiency and facilitating small-scale production. However, in the method disclosed in the aforementioned patent document, the binding degree between the K-MOF material and the polymer substrate in the working electrode is poor, which is not conducive to the adsorption and sustained monitoring of potassium ions.

[0008] Current research indicates that electrochemical sensors integrated with implantable devices can transmit information in real time, including vital signs, biomarker concentrations, and disease progression. However, developing self-monitoring systems for wearable (implantable) biosensors for clinical applications to continuously track patient status remains a challenge. Summary of the Invention

[0009] Therefore, the purpose of this invention is to provide an electrochemical sensor centered on ZIF-8 for detecting the ion content in urine and a method for detecting the ion content in urine using this sensor. The working electrode of this sensor is a ZIF-8 modified carbon electrode, which detects K+ ions in urine. + Na + Cl - When plasma ions are detected, the ZIF-8 composite porous sensing material can adsorb a large number of hydrated ions and ion carriers. The fixed ion carriers also improve the adsorption capacity and binding selectivity of ions, solving the problem of weak ion selectivity in traditional electrochemical sensors.

[0010] This invention also provides a urinary catheter containing the sensor, which allows for the detection of ions in the urine while simultaneously draining urine from a patient. This catheter exhibits a short response time for ion recognition, can continuously monitor ion concentrations in urine, and demonstrates excellent ion selectivity and long-lasting antibacterial properties, showing great potential and market prospects in the field of urine analysis.

[0011] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides an electrochemical sensor for detecting ion content in urine, centered on ZIF-8, comprising an electrode array including a working electrode, a counter electrode, and a reference electrode. The working electrode comprises a ZIF-8 modified carbon electrode, the counter electrode comprises a platinum electrode, and the reference electrode comprises a coated Ag / AgCl electrode. The ZIF-8 modified carbon electrode is obtained by coating a suspension containing a ZIF-8 composite porous sensing material onto a flexible substrate containing the carbon electrode, with a coating amount of 1-10 mg / cm³. 2 It is prepared after drying.

[0012] The electrode array has ≥1 working electrode, and the number of working electrodes can be configured differently depending on the type of ion to be measured in the urine.

[0013] Furthermore, the preparation process of the suspension containing the ZIF-8 composite porous sensing material includes the following steps: S1, a metal ion precursor solution is mixed with carboxyl or hydroxyl-functionalized polyvinyl chloride to form a dispersion. Then, an ion support, ligand, and ion localizing agent are added to the dispersion. After reacting at 60±5℃ for 1.5~2.5 hours, crude ZIF-8 composite porous sensitive material is obtained. In this process, the metal ion precursor, ion support, and ligand self-assemble through coordination to form polyhedral nodes, and the ligand rings bridge and construct a three-dimensional porous crystal structure with topology. S2, first wash the crude ZIF-8 composite porous sensitive material described in S1 with purified water, and then dry it at 75~85℃ to obtain the ZIF-8 composite porous sensitive material. S3, dissolve the ZIF-8 composite porous sensitive material described in S2 in a redistilled tetrahydrofuran solution containing bis(2-ethylhexyl) sebacate (plasticizer), stir and sonicate for 30-60 minutes to obtain a suspension containing the ZIF-8 composite porous sensitive material.

[0014] Further, in S1, the mass fraction of carboxyl or hydroxyl functionalized polyvinyl chloride in the dispersion is 30-50 wt%, and the remainder is the metal ion precursor solution; the metal ion precursor solution includes an aqueous solution of Zn(NO3)2, ZnCl2, ZnSO4 or Zn(Ac)2, with a concentration of 5-20 g / L.

[0015] Further, the ion carrier in S1 includes a potassium ion carrier, a sodium ion carrier, or a chloride ion carrier. The potassium ion carrier includes valinemycin, the sodium ion carrier includes N,N,N',N'-tetracyclohexyl-1,2-phenyldioxydiacetamide (sodium ion carrier III), and the chloride ion carrier includes tridodecylmethylammonium chloride. The ligand includes dimethylimidazole, and the ion localizing agent includes sodium tetraphenylborate. The amounts of the ion carrier, the ligand, and the ion localizing agent added are 1-5 wt%, 1-5 wt%, and 2-5 wt% of the mass of the dispersion, respectively.

[0016] Furthermore, the mass fraction of bis(2-ethylhexyl) sebacate in the tetrahydrofuran solution in S3 is 55~70wt%; the amount of ZIF-8 composite porous sensitive material added to the redistilled tetrahydrofuran solution containing bis(2-ethylhexyl) sebacate is 0.35-0.45g / mL.

[0017] Furthermore, the preparation process of the coated Ag / AgCl electrode includes the following steps: (1) Take 40-60 parts of sodium chloride, 79-80 parts of polyvinyl butyral, 1-3 parts of poloxamer, and 0.1-0.5 parts of multi-walled carbon nanotubes and dissolve them in 390-1600 parts of ethanol to obtain a mixed solution; the raw material components are in parts by weight. (2) Take 2~10μL of the mixed solution described in step (1) and drop it onto the surface of the Ag / AgCl electrode, and let it dry to obtain the solution.

[0018] The present invention further provides a method for detecting the ion content in urine, comprising the following steps: (A) Preparation of standard curve: The electrochemical sensor centered on ZIF-8 for detecting ion content in urine was immersed in potassium chloride standard solutions of different concentrations. Using an electrochemical workstation with a frequency range of 106 Hz-0.01 Hz, an amplitude of 5 mV, an initial voltage of open circuit voltage, and a settling time of 30 s, the response voltage values ​​of the electrochemical sensor at different concentrations were recorded. The electrochemical impedance spectroscopy was used to detect potassium ions of different concentrations and a voltage-concentration standard curve was plotted. (B) Detection of potassium ion content in urine: Immerse the above-mentioned electrochemical sensor centered on ZIF-8 for detecting ion content in urine into the urine sample to be tested, and use the method in step (A) to test and record the response voltage value of the electrochemical sensor. (C) Compare the response voltage value recorded in step (B) with the voltage-concentration standard curve in step (A) to obtain the ion content in the urine.

[0019] Further, the concentrations of the potassium chloride standard solutions of different concentrations mentioned in step (A) are 2, 20, 40, 80 and 160 mM (mM is millimoles per liter).

[0020] The present invention further provides an antibacterial urinary catheter containing the above-mentioned electrochemical sensor centered on ZIF-8 for detecting the ion content in urine.

[0021] Furthermore, the electrochemical sensor centered on ZIF-8 for detecting ion content in urine is fixedly connected to the catheter body by adhesive bonding or laser embedding.

[0022] The beneficial effects of this invention are: 1. The electrochemical sensor for detecting ion content in urine, centered on ZIF-8, of this invention comprises an electrode array. The working electrode of this array is a ZIF-8 modified carbon electrode, on which a ZIF-8 composite porous sensing material is loaded. This material can adsorb a large number of hydrated ions and ion carriers. The immobilized ion carriers also improve the adsorption capacity and binding selectivity of a specific ion, thus solving the problem of weak ion selectivity in traditional electrochemical sensors.

[0023] 2. The ZIF-8 composite porous sensing material of this invention is prepared by in-situ synthesis on carboxyl or hydroxyl-functionalized polyvinyl chloride (PVC) in a one-step method. The principle is as follows: the adsorption and coordination of Zn²⁺ by the functional groups (-OH / -COOH) on the PVC surface acts as nucleation centers, inducing ZIF-8 to nucleate and grow in situ at the interface. Simultaneously, a strong bond is achieved through chemical bonding, ultimately yielding a structurally stable and functionally synergistic porous composite material. ZIF-8 exhibits high bonding with carboxyl or hydroxyl-functionalized PVC and good mechanical properties, meeting the requirements for long-term monitoring of potassium in urine under immersion conditions. + Na + Cl - Plasma concentration. During the preparation of this material, the anti-interference capability of the working electrode was improved by optimizing the addition ratio of ion carrier and ion localizer.

[0024] 3. This invention integrates an electrochemical sensor centered on ZIF-8 for detecting ion content in urine with an implantable urinary catheter. While using this catheter to drain urine from the patient, ions in the urine can be detected in real time. The ZIF-8 composite porous sensing material is non-biotoxic, and the released zinc ions have good antibacterial activity and durability, improving the catheter's long-lasting antibacterial performance. It possesses enormous potential and market prospects in the field of urine analysis. Attached Figure Description

[0025] To more clearly illustrate the technical solution of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Appendix Figure 1 This is a SEM image of the ZIF-8 composite porous sensitive material prepared in Example 1 of this invention, with a scale bar of 200 nm. Appendix Figure 2 This is a schematic diagram of the electrode array arrangement contained in the electrochemical sensor in Embodiment 1 of the present invention, wherein 1 is the ion working electrode, 2 is the reference electrode, and 3 is the counter electrode; Appendix Figure 3 The figures show the voltage-concentration response of the working electrode when the sensors in Examples 1-3 and Comparative Example 1 of this invention detect potassium ion standard solutions of different concentrations. Appendix Figure 4 These are anti-interference test diagrams of the electrochemical sensors in Examples 1, 4, and 5 of this invention; Appendix Figure 5 This is a stability test diagram of the electrochemical sensor in Example 1 of the present invention; Appendix Figure 6 This is a real-time working curve of the electrochemical sensor used in Example 1 of the present invention to test urine. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. All mentioned embodiments are implemented based on the technical solutions of the present invention, and detailed implementation processes are given. However, it should be stated that the scope of protection of the present invention is not limited to the following embodiments.

[0028] The following embodiments provide detailed implementation procedures for the technical solutions of the present invention. Unless otherwise specified, the experimental methods used in the following experimental examples are conventional methods; unless otherwise specified, the materials and reagents used are commercially available.

[0029] Example 1 1. Preparation of a suspension containing ZIF-8 composite porous sensing material: 1.47 g of zinc nitrate hexahydrate was dissolved in 100 mL of aqueous solution. 80 g of poly(vinyl chloride-CO-acrylic acid) was added to the solution, and the mixture was stirred until completely dispersed. The solution was then heated to 60°C in a water bath. Next, 100 mL of an aqueous solution containing 3.24 g of dimethylimidazole, preheated to 60°C, was added to the solution. Then, 7.8 g of potassium ion carrier valamicin and 3.9 g of ion-localizing agent sodium tetraphenylborate were added to the mixed solution, and the mixture was stirred at 60°C for 2 h. The solution was then washed with purified water until the supernatant was colorless and dried in an oven at 80°C to obtain a white solid. Finally, the dried white solid was dissolved in 240 mL of redistilled tetrahydrofuran solution containing 157.1 g of bis(2-ethylhexyl) sebacate. The solution was magnetically stirred and ultrasonically vibrated for 30–60 min until completely dissolved, yielding a suspension containing ZIF-8 composite porous sensing material.

[0030] 2. Preparation of the working electrode: The suspension prepared in step 1 is coated onto a flexible substrate containing a carbon electrode, with a coating amount of 6 mg / cm³. 2 The carbon electrode was naturally air-dried to obtain ZIF-8 modified carbon electrode.

[0031] 3. Preparation of reference electrode: Dissolve 50 mg sodium chloride, 80 mg polyvinyl butyral, 2 mg poloxamer, and 0.3 mg multi-walled carbon nanotubes in 1 mL ethanol to obtain a mixed solution; add 6 μL of the mixed solution to the surface of the silver-silver chloride electrode, and dry at room temperature to obtain the coated Ag / AgCl electrode.

[0032] 4. Preparation of an electrochemical sensor for detecting ion content in urine centered on ZIF-8: using the ZIF-8 modified carbon electrode from step 2 as the working electrode, the film-modified Ag / AgCl electrode from step 3 as the reference electrode, and a platinum electrode as the counter electrode, the three electrodes are bonded together using double-sided medical tape. Figure 2 Then, an electrode array is formed. After assembly, an ion detection electrochemical sensor centered on ZIF-8 is obtained.

[0033] 5. Preparation of antibacterial urinary catheter: The ion detection electrochemical sensor centered on ZIF-8 from step 4 is bonded to the urinary catheter body, and its antibacterial performance is tested.

[0034] Example 2 The difference between this embodiment and Example 1 is as follows: The process of preparing the suspension containing ZIF-8 composite porous sensitive material in step 1 is as follows: 1.47 g of zinc nitrate hexahydrate was dissolved in 100 mL of aqueous solution, and then 60 g of poly(vinyl chloride-CO-acrylic acid) was added to the solution. The mixture was stirred to ensure complete dispersion and heated to 60°C in a water bath. Subsequently, 100 mL of aqueous solution containing 3.24 g of dimethylimidazole, preheated to 60°C, was added to the solution. Then, 7.8 g of potassium ion carrier valamicin and 3.9 g of ion-localizing agent sodium tetraphenylborate were added to the mixed solution, and the mixture was stirred at 60°C for 2 h. After washing with purified water, the sample was dried in an oven at 80°C. Finally, the dried sample was dissolved in 180 mL of redistilled tetrahydrofuran solution containing 117.8 g of bis(2-ethylhexyl) sebacate, and the solution was magnetically stirred and ultrasonically vibrated for 30-60 min to ensure complete dissolution, thus obtaining the suspension containing ZIF-8 composite porous sensitive material.

[0035] Example 3 The difference between this embodiment and Example 1 is as follows: The process of preparing the suspension containing ZIF-8 composite porous sensitive material in step 1 is as follows: 1.47 g of zinc nitrate hexahydrate was dissolved in 100 mL of aqueous solution, and then 100 g of poly(vinyl chloride-CO-acrylic acid) was added to the solution. The mixture was stirred to ensure complete dispersion and heated to 60°C in a water bath. Subsequently, 100 mL of aqueous solution containing 3.24 g of dimethylimidazole, preheated to 60°C, was added to the solution. Then, 7.8 g of potassium ion carrier valamicin and 3.9 g of ion-localizing agent sodium tetraphenylborate were added to the mixed solution, and the mixture was stirred at 60°C for 2 h. After washing with purified water, the sample was dried in an oven at 80°C. Finally, the dried sample was dissolved in 300 mL of tetrahydrofuran solution containing 196.4 g of bis(2-ethylhexyl) sebacate, magnetically stirred, and ultrasonically vibrated for 30-60 min to ensure complete dissolution, thus obtaining the suspension containing ZIF-8 composite porous sensitive material.

[0036] Example 4 The difference between this embodiment and Example 1 is as follows: The process of preparing the suspension containing ZIF-8 composite porous sensitive material in step 1 is as follows: 1.47 g of zinc nitrate hexahydrate was dissolved in 100 mL of aqueous solution, and then 60 g of poly(vinyl chloride-CO-acrylic acid) was added to the solution. The mixture was stirred to ensure complete dispersion and heated to 60°C in a water bath. Subsequently, 100 mL of aqueous solution containing 3.24 g of dimethylimidazole, preheated to 60°C, was added to the solution. Then, 7.8 g of potassium ion carrier and 7.8 g of sodium tetraphenylborate ion localization agent were added to the mixed solution, and the mixture was stirred at 60°C for 2 h. After washing with purified water, the sample was dried in an oven at 80°C. Finally, the dried sample was dissolved in 180 mL of redistilled tetrahydrofuran solution containing 117.8 g of bis(2-ethylhexyl) sebacate, and the solution was magnetically stirred and ultrasonically vibrated for 30-60 min to ensure complete dissolution, thus obtaining the suspension containing ZIF-8 composite porous sensitive material.

[0037] Example 5 The difference between this embodiment and Example 1 is as follows: The process for preparing the suspension containing ZIF-8 composite porous sensitive material in step 1 is as follows: 1.47 g of zinc nitrate hexahydrate was dissolved in 100 mL of aqueous solution, and then 60 g of poly(vinyl chloride-CO-acrylic acid) was added to the solution. The mixture was stirred to ensure complete dispersion and heated to 60°C in a water bath. Subsequently, 100 mL of aqueous solution containing 3.24 g of dimethylimidazole, preheated to 60°C, was added to the solution. Then, 7.8 g of potassium ion carrier, 2.6 g of sodium tetraphenylborate ion localizer, and 170.2 g of bis(2-ethylhexyl) sebacate were added to the mixed solution, and the mixture was stirred at 60°C for 2 h. After washing with purified water, the solution was dried in an oven at 80°C. Finally, the dried sample was dissolved in 180 mL of redistilled tetrahydrofuran solution containing 117.8 g of bis(2-ethylhexyl) sebacate, and the solution was magnetically stirred and ultrasonically vibrated for 30-60 min to completely dissolve it, thus obtaining a suspension containing ZIF-8 composite porous sensitive material.

[0038] Example 6 The difference between this embodiment and Example 1 is as follows: In step 1, a suspension containing ZIF-8 composite porous sensitive material is prepared: 1.47 g of zinc nitrate hexahydrate is dissolved in 100 mL of aqueous solution, and then 80 g of poly(vinyl chloride-CO-acrylic acid) is added to the solution. The mixture is stirred to ensure complete dispersion and heated to 60°C in a water bath. Subsequently, 100 mL of aqueous solution containing 3.24 g of dimethylimidazole, preheated to 60°C, is added to the solution. Then, 7.8 g of sodium ion carrier sodium green ETH 227 and 3.9 g of ion localizing agent sodium tetraphenylborate are added to the mixed solution, and the mixture is stirred at 60°C for 2 h. After washing with purified water, the mixture is dried in an oven at 80°C. The dried material is dissolved in 240 mL of redistilled tetrahydrofuran solution containing 157.1 g of bis(2-ethylhexyl) sebacate, and the solution is magnetically stirred and ultrasonically vibrated for 30-60 min to ensure complete dissolution, ultimately yielding a suspension containing ZIF-8 composite porous sensitive material.

[0039] Comparative Example 1 The difference between this comparative example and Example 1 is that step 1 involves preparing a suspension for potassium ion detection. The specific steps are as follows: 60 g of poly(vinyl chloride-CO-acrylic acid), 7.8 g of potassium ion carrier, and 7.8 g of sodium tetraphenylborate ion-localizing agent were stirred at 60°C for 2 h. After washing with purified water, the mixture was dried in an oven at 80°C. Finally, all the components were dissolved together in 180 mL of redistilled tetrahydrofuran solution containing 117.8 g of bis(2-ethylhexyl) sebacate, and the solution was magnetically stirred and ultrasonically vibrated for 30-60 min until completely dissolved, thus obtaining the potassium ion detection suspension.

[0040] Implementation effect analysis Test 1 Morphology testing of ZIF-8 composite porous sensitive materials The surface morphology of the ZIF-8 composite porous sensitive material prepared in Example 1 was tested using scanning electron microscopy. The test results are as follows: Figure 1 As shown. From Figure 1 As can be seen, the surface of the material has irregularly shaped, irregularly sized, and angular spherical crystals, and the crystals are densely arranged, which indicates that ZIF-8 is grown in situ on hydroxyl or carboxyl functionalized polyvinyl chloride.

[0041] Test 2 Sensitivity and Linearity Testing of Electrochemical Sensors The sensitivity and linearity of the electrochemical sensors in Examples 1-5 and Comparative Example 1 were tested respectively. The test method was as follows: potassium chloride standard solutions with concentrations of 2, 20, 40, 80, and 160 mM were prepared, and the electrochemical sensors were sequentially immersed in the prepared 2 to 160 mM potassium chloride standard solutions. The electrode array ( Figure 2 Connected to an electrochemical workstation, data was recorded after 30 seconds of settling at each concentration as the response voltage value for that concentration. After each concentration test, the electrode surface was cleaned with ultrapure water and dried with nitrogen gas. Test results are as follows: Figure 3 As shown.

[0042] from Figure 3 The test results show that, compared with the potassium ion working electrode without ZIF-8, the working electrode containing ZIF-8 has higher sensitivity to potassium ion standard solutions of different concentrations and exhibits good linearity. Furthermore, comparisons of Examples 1, 2, and 3 reveal that with increasing poly(vinyl chloride-CO-acrylic acid) solid content, the response of the working electrode to potassium ion standard solutions of different concentrations initially increases and then stabilizes. This indicates that the in-situ growth of ZIF-8 on carboxyl-functionalized PVC is affected by the solid content of PVC. When the solid content of PVC reaches 20 wt%, the amount of ZIF-8 synthesized in situ tends to stabilize, and the sensitivity of the working electrode also tends to stabilize, with a sensitivity of 0.101 V / log[K+] and a linearity of 0.996.

[0043] Test 3 Ion selectivity testing of electrochemical sensors The ion selectivity of the electrochemical sensors in Examples 1, 4, and 5 was tested. The test method was as follows: the ion selectivity of the working electrode was determined using the mixed solution method. First, the interfering ion NH4 was fixed. + The activity of K changes + The activity was used to prepare a series of standard solutions. The potential value of the working electrode in the solution was measured (test method is the same as test 2), and the potential value was plotted at different K. + The activity curves of the concentrations were used to calculate the ion selectivity coefficient. The test results are shown in Table 1 below.

[0044] The test results in Table 1 show that the ion selectivity coefficient of the working electrode first increases and then decreases with the increase of the ratio of valamicin to sodium tetraphenylborate. This indicates that the specific adsorption of potassium ions by valamicin is affected by the ratio of valamicin to sodium tetraphenylborate. When the ratio reaches 3:1, the active sites of sodium tetraphenylborate decrease, and the ion selectivity of the working electrode decreases. This demonstrates that optimizing the ratio of potassium ion carrier to anion localizer in this invention helps to improve the ion selectivity of the working electrode. Due to its special structure and bonding properties, the potassium ion carrier valamicin has a very strong adsorption capacity for potassium ions. Utilizing the specific adsorption of potassium ions by valamicin, the electrode can adsorb potassium ions in the solution. The anion localizer sodium tetraphenylborate can effectively remove the interference of anions, shorten the electrode response time, improve the electrode membrane performance, and enhance the membrane selectivity. However, the concentration of the ion localizer should not be too low, otherwise the ion selectivity will be affected to some extent.

[0045] Test 4 Anti-interference performance test of electrochemical sensor The anti-interference performance of the electrochemical sensors in Examples 1, 4, and 5 was tested. The test method was as follows: 2 mM potassium chloride (KCl) solution, 2 mM potassium chloride (KCl) solution + 5 mM ammonium chloride (NH4Cl) solution, 2 mM potassium chloride (KCl) solution + 0.5 mM magnesium chloride (MgCl2) solution, 2 mM potassium chloride (KCl) solution + 0.5 mM calcium chloride (CaCl2) solution, 2 mM potassium chloride (KCl) solution + 5 mM glucose (Glu) solution, and 4 mM potassium chloride solution were prepared respectively. The potassium ion working electrode was immersed in the prepared test solutions sequentially. The electrode array was connected to the electrochemical workstation through wires. Data was recorded for 150 seconds at each concentration (test method is the same as in Test 2). The data of the last 15 seconds was taken as the response voltage value at that concentration. After each concentration test, the electrode surface was cleaned with ultrapure water and dried with nitrogen. The test results are as follows. Figure 4 As shown.

[0046] from Figure 4 As can be seen, the response voltage of the working electrode first increases and then decreases with the increase of the ratio of valproic acid to sodium tetraphenylborate, which is consistent with the trend of ion selectivity. Furthermore, the working electrode prepared in Example 1 was not affected by other common ion interfering substances, demonstrating that the potassium ion working electrode has good specificity for potassium ions.

[0047] Test 5 Stability testing of electrochemical sensors The stability of the electrochemical sensor in Example 1 was tested. The test method was as follows: a 4 mM potassium chloride standard solution was prepared, and the potassium ion working electrode was immersed in the prepared 4 mM potassium chloride standard solution. The electrode array was connected to the electrochemical workstation through wires, and the data for 2 hours was recorded as the response voltage value at that concentration. After each concentration test, the electrode surface was cleaned with ultrapure water and dried with nitrogen gas. The test results are as follows. Figure 5 As shown.

[0048] from Figure 5 As can be seen, the response voltage drift value of the potassium ion working electrode is 0.87mV / h, which shows good stability.

[0049] Test 6 Detecting potassium ion content in urine The potassium ion content in urine was tested using the electrochemical sensor described in Example 1. The test method was as follows: (1) Preparation of standard curve: Immerse the electrochemical sensor prepared in step 4 into potassium chloride standard solution. At a frequency range of 106Hz~0.01Hz, an amplitude of 5mV, an initial voltage of open circuit voltage, and a standing time of 30s, use electrochemical impedance spectroscopy to detect potassium ions of different concentrations.

[0050] (2) Detection of potassium ion content in urine: 100 mL of human urine was collected, and a self-made electrochemical sensor was used to monitor the urine. Then, 1 mM potassium chloride standard solution was added to the human urine sample twice consecutively, and the change in response voltage was observed. The test results are as follows: Figure 6 As shown.

[0051] from Figure 6 As can be seen, the potassium ion working electrode can respond promptly to changes in the concentration of potassium ions in urine, showing a change in response voltage, indicating that the potassium ion working electrode of the present invention has high sensitivity in real-time monitoring.

[0052] Test 7 Antibacterial performance test of antibacterial urinary catheter The antibacterial properties of the antibacterial catheters in Example 1 and Comparative Example 1 were tested. The test method was as follows: *Escherichia coli* (ATCC11229) and *Staphylococcus aureus* (ATCC6538) were selected, and the antibacterial properties of the self-made antibacterial medical catheter and ordinary catheter were tested according to the standard *SN-T 3122-2012 Test Method for Antibacterial Properties of Inorganic Antibacterial Materials*, applicable to film-type antibacterial materials. Bacteria were quantitatively inoculated onto the test samples, and a film was used to ensure uniform contact between the bacteria and the sample. After a certain period of incubation, the number of viable bacteria in the samples was measured, and the sterilization rate was calculated. The test results are shown in Table 2 below.

[0053] As shown in Table 2, the antibacterial rates of Staphylococcus aureus, Escherichia coli, and Candida albicans in the urinary catheter integrated with the ZIF-8-centered potassium ion detection sensor were significantly higher than those in the urinary catheter integrated with the potassium ion detection sensor without ZIF-8. Therefore, the in-situ synthesis of ZIF-8 on the working electrode greatly improved the antibacterial performance of the urinary catheter. Further test results indicate that ZIF-8, as a typical representative of ZIFs materials, is a non-toxic nanomolecule that can be integrated into implantable urinary catheters. Furthermore, the zinc ions it releases exhibit good antibacterial activity and durability, significantly improving the long-lasting antibacterial performance of the urinary catheter.

[0054] In summary, the electrochemical sensor for detecting ion content in urine, centered on ZIF-8, provided by this invention, has a ZIF-8-modified carbon electrode as its working electrode. This sensor is effective in detecting K+ ions in urine. + Na + Cl - When detecting plasma ions, the ZIF-8 composite porous sensitive material can adsorb a large number of hydrated ions and ion carriers. The immobilized ion carriers also improve the adsorption capacity and binding selectivity of ions, solving the problem of weak ion selectivity in traditional electrochemical sensors. The urinary catheter containing this sensor provided by this invention allows for the detection of ions in urine while simultaneously draining urine from a patient. This catheter has a short ion recognition response time, can continuously monitor ion concentration in urine, and exhibits good ion selectivity and long-lasting antibacterial properties, demonstrating great potential and market prospects in the field of urine analysis.

[0055] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An electrochemical sensor centered on ZIF-8 for detecting ion content in urine, characterized in that, An electrode array is provided, comprising a working electrode, a counter electrode, and a reference electrode; the working electrode comprises a ZIF-8 modified carbon electrode, the counter electrode comprises a platinum electrode, and the reference electrode comprises a coating-modified Ag / AgCl electrode; the ZIF-8 modified carbon electrode is prepared by first coating a suspension containing a ZIF-8 composite porous sensitive material onto a flexible substrate containing a carbon electrode, and then drying it.

2. The electrochemical sensor for detecting ion content in urine centered on ZIF-8 as described in claim 1, characterized in that, The preparation process of the suspension containing the ZIF-8 composite porous sensitive material includes the following steps: S1, a metal ion precursor solution is mixed with carboxyl or hydroxyl functionalized polyvinyl chloride to form a dispersion, and then an ion carrier, ligand and ion localizing agent are added to the dispersion. After reacting at 60±5℃ for 1.5~2.5 hours, crude ZIF-8 composite porous sensitive material is obtained. S2, first wash the crude ZIF-8 composite porous sensitive material described in S1 with purified water, and then dry it at 75~85℃ to obtain the ZIF-8 composite porous sensitive material. S3, dissolve the ZIF-8 composite porous sensitive material described in S2 in a redistilled tetrahydrofuran solution containing bis(2-ethylhexyl) sebacate, stir and sonicate for 30-60 minutes to obtain a suspension containing the ZIF-8 composite porous sensitive material.

3. The electrochemical sensor for detecting ion content in urine centered on ZIF-8 as described in claim 2, characterized in that, The dispersion in S1 contains 30-50 wt% of carboxyl or hydroxyl-functionalized polyvinyl chloride, with the remainder being the metal ion precursor solution; the metal ion precursor solution includes an aqueous solution of Zn(NO3)2, ZnCl2, ZnSO4 or Zn(Ac)2, with a concentration of 5-20 g / L.

4. The electrochemical sensor for detecting ion content in urine centered on ZIF-8 as described in claim 2, characterized in that, The ion carrier in S1 includes a potassium ion carrier, a sodium ion carrier, or a chloride ion carrier. The potassium ion carrier includes valinemycin, the sodium ion carrier includes N,N,N',N'-tetracyclohexyl-1,2-phenyldioxydiacetamide, and the chloride ion carrier includes tris(2-)-dodecylmethylammonium chloride. The ligand includes dimethylimidazole, and the ion localizing agent includes sodium tetraphenylborate. The amounts of the ion carrier, ligand, and ion localizing agent added are 1-5 wt%, 1-5 wt%, and 2-5 wt% of the mass of the dispersion, respectively.

5. The electrochemical sensor for detecting ion content in urine centered on ZIF-8 as described in claim 2, characterized in that, The mass fraction of bis(2-ethylhexyl) sebacate in the tetrahydrofuran solution in S3 is 55~70wt%; the amount of ZIF-8 composite porous sensitive material added to the redistilled tetrahydrofuran solution containing bis(2-ethylhexyl) sebacate is 0.35-0.45g / mL.

6. The electrochemical sensor for detecting ion content in urine centered on ZIF-8 as described in claim 1, characterized in that, The preparation process of the coating-modified Ag / AgCl electrode includes the following steps: (1) Take 40-60 parts of sodium chloride, 79-80 parts of polyvinyl butyral, 1-3 parts of poloxamer, and 0.1-0.5 parts of multi-walled carbon nanotubes and dissolve them in 390-1600 parts of ethanol to obtain a mixed solution; the raw material components are in parts by weight. (2) Take 2~10μL of the mixed solution described in step (1) and drop it onto the surface of the Ag / AgCl electrode, and let it dry to obtain the solution.

7. A method for detecting the ion content in urine, characterized in that, Includes the following steps: (A) Preparation of standard curve: The electrochemical sensor for detecting ion content in urine centered on ZIF-8 as described in any one of claims 1 to 6 is immersed in potassium chloride standard solutions of different concentrations. The response voltage values ​​of the electrochemical sensor at different concentrations are recorded at a frequency range of 106 Hz to 0.01 Hz, an amplitude of 5 mV, an initial voltage of open circuit voltage, and a settling time of 30 s. The electrochemical impedance spectroscopy is used to detect potassium ions of different concentrations and a voltage-concentration standard curve is plotted. (B) Detection of ion content in urine: Immerse the electrochemical sensor for detecting ion content in urine centered on ZIF-8 as described in any one of claims 1 to 6 into the urine sample to be tested, and use the method in step (A) to test and record the response voltage value of the electrochemical sensor. (C) Compare the response voltage value recorded in step (B) with the voltage-concentration standard curve in step (A) to obtain the ion content in the urine.

8. The method for detecting ion content in urine as described in claim 7, characterized in that, The concentrations of the potassium chloride standard solutions in step (A) are 2, 20, 40, 80 and 160 mM, respectively.

9. An antibacterial urinary catheter comprising an electrochemical sensor centered on ZIF-8 for detecting ion content in urine as described in any one of claims 1 to 6.

10. The antibacterial urinary catheter as described in claim 9, characterized in that, The electrochemical sensor centered on ZIF-8 for detecting ion content in urine is fixedly connected to the catheter body by adhesive bonding or laser embedding.

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