A Y-type polypeptide-modified ion-selective electrode, its preparation method and application

Abstract

This invention relates to the field of electrochemical detection technology, specifically to a Y-type peptide-modified ion-selective electrode, comprising an electrode substrate, a solid-state transduction layer, an ion-selective membrane, and an antifouling and antibacterial layer. A conductive porous metal-organic framework (MOF) material is used as the solid-state transduction layer, whose large specific surface area provides numerous active sites for ion transfer, promoting ion transport and conversion. By employing different ion exchange membranes, the detection of multiple different ions can be achieved. Simultaneously, a peptide is used as an antifouling and antibacterial layer attached to the surface of the ion-selective membrane, modifying the ion-selective electrode and integrating both anti-adhesion and bactericidal properties. This solves the problem of biofouling caused by biomass adhesion or growth on the electrode surface during seawater detection, providing excellent antifouling performance and enabling more accurate ion detection. The invention also provides a method for preparing the ion-selective electrode and its applications.

Description

Technical Field

[0001] This invention relates to the field of electrochemical detection technology, specifically to a Y-type polypeptide-modified ion-selective electrode, its preparation method, and its application. Background Technology

[0002] All-solid-state ion-selective electrodes (SC-ISEs) are widely used in environmental monitoring technology due to their advantages such as high sensitivity, portability, and fast response. However, their application in marine environments faces challenges, including the growth of bacteria or microorganisms in seawater and the formation of biofouling on electrode surfaces. Biofouling refers to the undesirable adhesion of organisms and their metabolites to electrode surfaces. When proteins, bacteria, and other biomolecules adhere and accumulate, they eventually form unique biofilms. Marine biofouling on electrode surfaces not only alters the interfacial morphology but also interferes with the interaction between the electrode and ions in the solution. This interference reduces the electrode's selectivity and response capability, severely impacting the analytical accuracy and stability during long-term monitoring in marine environments.

[0003] Currently, commonly used surface-modified antifouling materials include hydrophilic materials such as polyethylene glycol-based polymers and oligomeric polyethylene glycols. Although these materials exhibit excellent antifouling properties, they are prone to oxidative damage, which limits their further application. In addition, there are widely used antimicrobial materials such as nano-silver and quaternary ammonium compounds, but they may cause potential environmental pollution problems to seawater systems.

[0004] Therefore, it is of great significance to develop an all-solid-state ion-selective electrode that solves the problem of biological pollution and has environmentally friendly, antifouling and antibacterial properties. Summary of the Invention

[0005] To address the technical problems in existing technologies, the present invention aims to provide a Y-type peptide-modified ion-selective electrode. Based on a conductive MOF and modified with a Y-type peptide, it possesses multiple functions including anti-adhesion and antibacterial properties, solving the problem of biofouling on the electrode surface. The prepared SC-ISE exhibits excellent antifouling performance and maintains good potential response during long-term testing. Importantly, the prepared electrode achieves accurate detection of multiple ions, including potassium ions, in a real seawater environment. The present invention also provides its preparation method and application performance testing.

[0006] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0007] On one hand, the present invention provides a Y-type polypeptide-modified ion-selective electrode, comprising an electrode substrate, a solid-state transduction layer, an ion-selective membrane, and an antifouling and antibacterial layer. The solid-state transduction layer is self-assembled on the electrode substrate and is a conductive porous metal-organic framework material. The ion-selective membrane is disposed on the solid-state transduction layer, and the antifouling and antibacterial layer is disposed on the surface of the ion-selective membrane.

[0008] In this application, conductive porous metal-organic framework (MOF) materials are used as solid-state transduction layers. Their large specific surface area provides many active sites for ion transfer, promoting ion transport and conversion. By using different ion exchange membranes, the detection of various ions can be achieved. At the same time, peptides are used as antifouling and antibacterial layers attached to the surface of the ion-selective membrane to modify the ion-selective electrode, integrating both anti-adhesion and bactericidal properties. This solves the problem of biofouling caused by the attachment or growth of biomass on the electrode surface during seawater detection, providing good antifouling performance and enabling more accurate ion detection.

[0009] Based on the above technical solution, the electrode substrate is a gold electrode; the solid-state transduction layer uses Ni3(HITP)2 as the MOF material; the ion-selective membrane is one of potassium ion-selective membrane, calcium ion-selective membrane, magnesium ion-selective membrane, lead ion-selective membrane, copper ion-selective membrane, and sodium ion-selective membrane; and the antifouling and antibacterial layer is a Y-type polypeptide.

[0010] Based on the above technical solution, the Y-type polypeptide includes an antimicrobial chain, an antimicrobial chain, and an adhesion amino acid, with the sequence DOPA-K(RWRWRW-)EKEKEKEK.

[0011] Modifying electrodes with peptides, which are environmentally friendly, easy to synthesize and store, cost-effective, and structurally tunable, is of significant research value in antifouling and antibacterial applications. Specifically, the Y-type peptide used in this application contains an anti-adhesion chain that prevents organisms from adhering to the electrode surface, an antibacterial chain that effectively removes bacteria accumulated on the electrode, and adhesion amino acids that enhance the peptide's adhesion to ion-selective membrane surfaces.

[0012] Taking a potassium ion selective electrode as an example, the transport mechanism of potassium ions in the antifouling and antibacterial layer formed by peptides was investigated, as follows:

[0013] Massive parallel atomic / molecular simulations (MD) were performed using the software LAMMPS23. An adsorption simulation model was constructed using a Y-type polypeptide as an ion transport interface coating in a 0.1M KCl solution system, as shown in the figure. Figure 1 As shown in Figure a. After adsorption reaches equilibrium, potassium ions can be observed to pass smoothly through the polypeptide interface, as shown in Figure a. Figure 1 As shown in Figure b. To gain a more intuitive understanding of the potassium ion density distribution, molecular distances in three-dimensional space were measured to verify potassium ion transport, as shown in Figure b. Figure 1 As shown in cd. In Figure 1 In the middle of the middle, K + Ion diffusion is very rapid at 22 ps, after which it tends to stabilize. The diffusion coefficient calculated by simulation is 6.14 Å. 2 ps -1 This indicates that potassium ions diffuse rapidly within the peptide coating. The radial distribution function (RDF) shows that nitrogen (N) in the peptide molecules binds effectively to potassium ions over a radial distance of 2-5 Å, indicating adsorption and desorption of potassium ions within the peptide layer. Figure 1 As shown in f. In general, K + Successful permeation through peptide membranes can be attributed to three main reasons: (1) the membranes composed of Y-type peptides have a porous structure, which can act as channels to facilitate the transport of ions at the peptide interface, including the adsorption, migration, and desorption of ions within the pores; (2) the nitrogen element in the amino group of the peptide molecule has lone pairs of electrons and exhibits significant electrophilicity, which increases the affinity of nitrogen for positively charged K+. + The possibility of ion interactions or adsorption; (3) the electrophilicity of nitrogen may lead to interactions with K + The interaction of ions involves mechanisms such as charge attraction, hydrogen bond formation, or other interaction methods.

[0014] On the other hand, the present invention provides a method for preparing a Y-type peptide-modified ion-selective electrode, comprising the following steps:

[0015] Step 1: Pretreatment of the electrode substrate; the electrode substrate is cleaned, polished, and activated before use.

[0016] Step 2, MOF material preparation: The electrode substrate pretreated in Step 1 is placed in a flask, and a conductive porous MOF material is used as a solid transconducting layer to perform a self-assembly process on the electrode substrate to obtain an electrode substrate with a self-assembled solid transconducting layer.

[0017] Step 3: Preparation of ion-selective membrane; Prepare ion-selective membrane solution, and drop the ion-selective membrane solution onto the self-assembled solid transconducting layer obtained in step 2 to form an ion-selective membrane; The electrode prepared is denoted as Au / MOF / ISM;

[0018] Step four, preparation of ion-selective electrode; an antifouling and antibacterial layer is set on the ion-selective membrane formed in step three to obtain the final ion-selective electrode, which is denoted as Au / MOF / ISM / pep.

[0019] Based on the above technical solution, in step one, the electrode substrate is a gold electrode, and the pretreatment includes the following steps:

[0020] S1, the gold electrode is cleaned with ultrasonic ultrapure water for 10 minutes and then dried with nitrogen.

[0021] S2, the electrode is at a concentration of 100 mmol L -1 In a sodium hydroxide solution at 0.1 V s -1 The rate is 100 cycles within a potential range of -0.5 to 1.5 V; electrochemical performance testing and evaluation through cyclic scanning can help understand the electrochemical activity, redox behavior and surface characteristics of the electrode.

[0022] S3, the gold electrode is precisely polished using 0.3μm and 0.05μm alumina polishing powder on a special polishing cloth; after polishing, the electrode is cleaned by ultrasonic treatment with ultrapure water.

[0023] S4. Immerse the electrode in a mixed aqueous solution containing 30wt% H2SO4 and 30wt% H2O2 for 15-20 minutes, wherein the volume ratio of H2SO4 to H2O2 solution is 3:1; further clean the electrode surface to remove any possible organic residues or oxide layer and increase the active sites on the electrode surface.

[0024] S5, the electrode is at a concentration of 100 mmol / L -1 The solution was circulated in H₂SO₄ solution at a potential range of -0.2 to 1.5 V, with a circulation scan rate of 0.1 V / s. -1 The process was repeated 25 times. After further activation, the electrode was thoroughly rinsed with ultrapure water and set aside for later use.

[0025] Based on the above technical solution, in step two, self-assembled Ni3(HITP)2 is used as the MOF material. The preparation process of Ni3(HITP)2 includes the following steps: 20.85 mg of nickel acetate tetrahydrate is dissolved in 9 mL of dimethyl sulfoxide, and ultrasonically treated for 2 min to prepare solution A, which is then preheated to 65 °C; subsequently, 30 mg of HATP·6HCl solution is added to 9 mL of ultrapure water and stirred until the solution is homogeneous, and then 12 mL of 4 mol / L... -1 Solution B was obtained from NaOAc aqueous solution. Solution A and solution B were mixed evenly and stirred at 65°C for 2 hours to form a black suspension. After the synthesis was completed, the gold electrode with the self-assembled solid transconductance layer was extracted, washed continuously with ultrapure water and methanol, and dried at room temperature.

[0026] Based on the above technical solution, the ion-selective membrane in step three is a potassium ion-selective membrane. The preparation process includes the following steps: dissolving 4 mg of valproic acid, 1 mg of NaTFPB, 65.4 mg of PVC, and 143.4 μL of LDS in 1500 μL of THF to form a potassium ion-selective membrane solution; adding 80 μL of the potassium ion-selective membrane solution to the self-assembled MOF material on the surface of the gold electrode and letting it stand overnight; allowing the membrane to dry naturally at room temperature; the resulting electrode is denoted as Au / MOF / K. + -ISM. That is, an ion-selective electrode that has not undergone peptide incubation.

[0027] Based on the above technical solution, the ion-selective electrode in step four is a potassium ion-selective electrode, and the preparation process includes the following steps: incubating 10 μL of 0.2 mg / mL water on the surface of the potassium ion-selective membrane. -1 Y-type polypeptide was incubated for 4 hours; the resulting electrode was denoted as Au / MOF / K. + -ISM / pep. The Y-type polypeptide was designed and synthesized by Suzhou Modifu Biotechnology Co., Ltd., with the sequence DOPA-K(RWRWRW-)EKEKEKEK.

[0028] Taking potassium ions as an example, the Au / MOF / K + The transduction and antifouling mechanisms of ISM / PEP are analyzed as follows:

[0029] Ni3(HITP)2 is a π-d conjugated MOF (Metal-Oxide-Facility) that forms π-d orbitals through strong metal-ligand orbital hybridization between the d orbitals of transition metal ions and the π orbitals of organic ligands. The delocalized charge present throughout the system contributes to enhanced conductivity. Simultaneously, as an energy storage material, it exhibits a large double-layer capacitance, and its large specific surface area provides abundant active sites; this characteristic is advantageous for the efficient conversion and transport of ions and electrons. Figure 2 As shown in Figure a, the ion-electron process of the prepared ion-selective electrode involves the complexation of potassium ions with substances within the ion-selective membrane. After passing through the ion membrane, potassium ions reach the interface, where charged ions KLn within the ion-selective membrane... + The ion-electron pair capacitively couples with electrons in Ni3(HITP)2, thus converting the ion signal into an electrical signal output. Simultaneously, the excellent conductivity and large specific surface area of ​​Ni3(HITP)2 accelerate ion-electron transfer, as shown in the EIS diagram. Figure 2 As shown in Figure b, this enhances the short-term stability of the electrode. Figure 1 As shown in Figure b, with Au / K + Compared to -ISM, Au / MOF / K +-ISM exhibits lower membrane resistance (Rb = 6.7 kΩ) and Rct (9.6 kΩ) in the high-frequency region. This is due to the larger specific surface area of ​​porous Ni3(HITP)2, which provides more active sites for ions and promotes ion-electron transfer. Furthermore, due to the non-conductive nature of the antifouling peptide membrane, the Rct of the ion-selective electrode increases after incubation with the peptide. Despite the increased impedance, the effect on interfacial ion transport is minimized due to the large ion transport channels present in the peptide layer.

[0030] The Y-type polypeptide used in this application contains a resistant peptide chain and an antimicrobial peptide chain, achieving dual functions of anti-contamination and sterilization. This ensures that bacteria in contact with the testing system are killed while preventing them from adhering to the electrode surface and forming biofouling. Figure 1 As shown in Figure a, the antifouling mechanism of the Y-type polypeptide is to improve the hydrophobic potassium ion membrane interface (CA=103±0.12°) into a hydrophilic interface with a contact angle of 24±0.08°, as... Figure 2 As shown in Figure c, water at the hydrophilic peptide interface competes with contaminants, easily forming a hydrated layer on the peptide surface. This reduces the non-specific adsorption of contaminants at the electrode interface, thus achieving anti-fouling. Furthermore, maintaining the peptide in a near-neutral state in the testing environment eliminates interfacial charge interactions, effectively preventing the non-specific adsorption of contaminants.

[0031] Furthermore, this invention also provides the application of a Y-type polypeptide-modified ion-selective electrode in the detection of potassium, calcium, magnesium, lead, copper, or sodium ions in seawater.

[0032] Based on the above technical solution, the Nernst response range of the ion-selective electrode for potassium ion detection is 10. -8 -10 -3 M, detection limit is 2.51×10 -9 M, with a response time of 2-8 seconds.

[0033] The beneficial effects of the technical solution provided by this invention are as follows:

[0034] 1. This application employs conductive porous metal-organic framework (MOF) materials as the solid-state transduction layer. Their large specific surface area provides numerous active sites for ion transfer, promoting ion transport and conversion. By using different ion exchange membranes, the detection of various ions can be achieved. Simultaneously, peptides are used as an antifouling and antibacterial layer attached to the surface of the ion-selective membrane to modify the ion-selective electrode, integrating both anti-adhesion and bactericidal properties. This solves the problem of biofouling caused by biomass adhesion or growth on the electrode surface during seawater detection, providing excellent antifouling performance and enabling more accurate ion detection. A method for preparing the ion-selective electrode is also provided.

[0035] 2. This application also provides the application of the prepared ion-selective electrode in the detection of multiple ions in seawater, especially in the detection of potassium ions, where the Nernst response range of the ion-selective electrode is 10. -8 -10 -3 M, detection limit is 2.51×10 -9 M, with a response time of 2-8 seconds, demonstrates more accurate and superior detection capabilities. Attached Figure Description

[0036] Figure 1 In the diagram, ab represents the adsorption equilibrium configuration; cd represents the three-dimensional density distribution of the initial and final adsorption states; and e represents the molecular dynamics simulation K. + Schematic diagram of diffusion coefficient; f is K + -N radial distribution function plot;

[0037] Figure 2 (a) Schematic diagram of the response mechanism of the antifouling potassium ion selective electrode; (b) Au / MOF / K + -ISM / pep, Au / MOF / K + -ISM and Au / K + -ISM impedance spectrum; (c)Au / MOF / K + -ISM / pep and Au / MOF / K + - Schematic diagram of contact angles on the ISM surface;

[0038] Figure 3 In the image, a is the SEM image of MOF / Au, and b is the energy spectrum of MOF (c: carbon, d: nitrogen, f: sulfur, e: nickel).

[0039] Figure 4 In the image, a represents the X-ray photoelectron spectrum of the MOF material; b represents the X-ray photoelectron spectrum at 10... -3 The scan rate in the M KCl solution was 100 mV / s. -1 Cyclic voltammetry curves of Au and Au / MOF electrodes at 10 °C; c shows the N2 adsorption-desorption isotherm and pore size distribution of the MOF material (inset); d shows the cyclic voltammetry curves of Au and Au / MOF electrodes at 10 °C. -3 Impedance spectrum at open circuit potential in M ​​KCl solution;

[0040] Figure 5 Image a shows typical growth curves (NACV and incubation time) of *E. coli* with different electrodes; image b shows typical growth curves (NACV and incubation time) of *Staphylococcus aureus* with different electrodes; images cd show *E. coli* and *Staphylococcus aureus* colonies on different coated surfaces; image ef shows Au / MOF / K... + -ISM electrode, gh is Au / MOF / K +- Fluorescence microscopy images of the ISM / pep electrode surface, schematic diagram of the number of live bacteria (SYTO 9 green staining) and dead bacteria (PI red staining);

[0041] Figure 6 In this context, 'a' represents Au / MOF / K. + -ISM / pep, Au / MOF / K + -ISM and Au / K + -ISM at 10 -10.5 -10 -3 Potential response diagrams within the concentration range of M; b shows the potential response diagrams of the three electrodes over time.

[0042] Figure 7 In the middle, a represents Au / MOF / K. + -ISM / pep, Au / MOF / K + -ISM and Au / K + -ISM chronopotential diagram; b is Au / MOF / K + -ISM / pep, Au / MOF / K + - Long-term stability spectrum of the ISM electrode in a bacterial solution environment; c represents the effect of O2, CO2, and light irradiation on Au / MOF / K + -ISM / pep potential stability effect spectrum; d represents Au / MOF / K + -ISM / pep, Au / MOF / K + -Selectivity coefficient plot of ISM; Detailed Implementation

[0043] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items. It should be understood that, unless otherwise specified, all the various materials used in this invention are commercially available.

[0045] Example 1

[0046] This invention provides a Y-type peptide-modified ion-selective electrode, comprising an electrode substrate, a solid-state transduction layer, an ion-selective membrane, and an antifouling and antibacterial layer. The solid-state transduction layer is self-assembled on the electrode substrate and is a conductive porous metal-organic framework material. The ion-selective membrane is disposed on the solid-state transduction layer, and the antifouling and antibacterial layer is disposed on the surface of the ion-selective membrane. Specifically, the electrode substrate is a gold electrode; the solid-state transduction layer uses Ni3(HITP)2 as the MOF material; the ion-selective membrane is a potassium ion-selective membrane; and the antifouling and antibacterial layer is a Y-type peptide, which includes an antimicrobial chain, an antimicrobial chain, and an adhesion amino acid, with the sequence DOPA-K(RWRWRW-)EKEKEKEK.

[0047] This invention provides a method for preparing a Y-type polypeptide-modified ion-selective electrode, comprising the following steps:

[0048] Step 1, Pretreatment of the electrode substrate; including: S1, the gold electrode is ultrasonically cleaned with ultrapure water for 10 min and dried with nitrogen; S2, the electrode is subjected to a concentration of 100 mmol / L... -1 In a sodium hydroxide solution at 0.1 V s -1 The rate is cycled 100 times within a potential range of -0.5 to 1.5 V; S3, the gold electrode is precisely polished on a special polishing cloth using 0.3 μm and 0.05 μm alumina polishing powder; after polishing, the electrode is cleaned by ultrasonic treatment with ultrapure water; S4, the electrode is immersed in a mixed aqueous solution containing 30 wt% H2SO4 and 30 wt% H2O2 for 15-20 min, wherein the volume ratio of H2SO4 to H2O2 solution is 3:1; S5, the electrode is subjected to a concentration of 100 mmol L... -1 The solution was circulated in H₂SO₄ solution at a potential range of -0.2 to 1.5 V, with a circulation scan rate of 0.1 V / s. -1 The process was repeated 25 times. After further activation, the electrode was thoroughly rinsed with ultrapure water and set aside for later use.

[0049] Step 2, MOF material preparation; self-assembled Ni3(HITP)2 was used as the MOF material. The preparation process of Ni3(HITP)2 included the following steps: 20.85 mg of nickel acetate tetrahydrate was dissolved in 9 mL of dimethyl sulfoxide, and the solution was sonicated for 2 min to prepare solution A, which was then preheated to 65 °C; subsequently, 30 mg of HATP·6HCl solution was added to 9 mL of ultrapure water and stirred until the solution was homogeneous, and then 12 mL of 4 mol / L... -1 Solution B was obtained from NaOAc aqueous solution. Solution A and solution B were mixed evenly and stirred at 65°C for 2 hours to form a black suspension. After the synthesis was completed, the gold electrode with the self-assembled solid transconductance layer was extracted, washed continuously with ultrapure water and methanol, and dried at room temperature.

[0050] Step 3: Preparation of the potassium ion-selective membrane; specifically including the following steps: Dissolve 4 mg of valproic acid, 1 mg of NaTFPB, 65.4 mg of PVC and 143.4 μL of LDS in 1500 μL of THF to form a potassium ion-selective membrane (ISM) solution; drop 80 μL of the potassium ion-selective membrane solution onto the self-assembled MOF material on the gold electrode surface and let it stand overnight; allow the membrane to dry naturally at room temperature; the prepared electrode is denoted as Au / MOF / K + -ISM.

[0051] Step four, preparation of the potassium ion selective electrode; an antifouling and antibacterial layer is applied to the ion selective membrane formed in step three to obtain the final potassium ion selective electrode; specifically, this includes the following steps: incubating 10 μL of 0.2 mg / mL solution on the surface of the ion selective membrane. -1 Y-type polypeptide was incubated for 4 hours; the resulting electrode was denoted as Au / MOF / K. + -ISM / pep.

[0052] This invention provides an application of a Y-type peptide-modified ion-selective electrode in the detection of potassium ions in seawater; the Nernst response range of the ion-selective electrode is 10. -8 -10 -3 M, detection limit is 2.51×10 -9 M, with a response time of 2-8 seconds.

[0053] Example 2

[0054] This embodiment studies the morphology of conductive porous metal-organic framework (MOF) materials in solid-state transconducting layers, as detailed below:

[0055] The surface morphology of the solid transconductance layer of MOF material was characterized using scanning electron microscopy, and the images are shown below. Figure 3 As shown in the figure, the spectrum reveals the self-assembly of MOF materials on the Au electrode surface, forming a micro / nanofiber array. The fiber length is approximately 1 μm, and the diameter ranges from 80 to 110 nm. EDX results are shown below. Figure 3 As shown in Figure BE, the presence of C, N, and Ni elements is revealed, confirming the MOF material formed by nickel and organic ligands. The chemical state of the Ni3(HITP)2 surface elements was further investigated using XPS. Figure 4 The measured spectra in sample a confirmed the presence of Ni, N, C, and O resonance peaks in both the material itself and the water guest molecules. To further investigate the capacitance properties of Ni3(HITP)2, CV experiments were also conducted, such as... Figure 4As shown in b, the CV curve of the self-assembled Ni3(HITP)2 gold electrode shows a larger and more rectangular current window compared to the bare gold electrode, indicating that Ni3(HITP)2 has a larger capacitance. This is attributed to the larger specific surface area of ​​Ni3(HITP)2. Figure 4 As shown in Figure c, the N2 adsorption-desorption isotherm indicates that the calculated specific surface area of ​​Ni3(HITP)2 is 325.6 m²g. -1 , Figure 4 The illustration in Figure c further confirms the porous structure of Ni3(HITP)2, with the main micropore size around 1 nm. Furthermore, the impedance spectrum of the solid-state transconductance layer is as follows: Figure 4 As shown in d, the charge transfer resistance (Rct) of Ni3(HITP)2 is 3.436 kΩ cm², which confirms that Ni3(HITP)2 has a relatively fast electron transfer rate at the electrode-solution interface.

[0056] Example 3

[0057] This embodiment tests the antifouling performance of the potassium ion selective electrode prepared above, as detailed below:

[0058] Potassium ion selective electrode incubated with peptides, namely Au / MOF / K + -ISM / pep electrode and electrode without peptide incubation, namely Au / MOF / K + -ISM electrodes were at 10 6 CFU mL -1 The bacteria were immersed in a solution for 12 hours. After rinsing, the electrodes were diluted, and bacterial growth kinetics were monitored in real time using a 32-channel non-contact conductivity sensor. The bacterial solution used consisted of typical Gram-positive bacteria (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli). Figure 4 As shown in ab, the positive control (inoculation concentration of 10) 6 CFU mL -1 Diluted bacterial solution, Au / MOF / K + -ISM / pep electrode and Au / MOF / K + The -ISM ​​electrode yielded the expected S-shaped curve. It is noteworthy that the Au / MOF / K ratio was observed in both E. coli and Staphylococcus aureus solutions. + -Microbial growth curves after immersion of bacterial solution on the surface of ISM / PEP electrode and Au / MOF / K + Compared to the -ISM ​​electrode, it exhibits a longer hysteresis period. Furthermore, the onset of the exponential phase is delayed, as shown in the growth rate curve (see...). Figure 5The insets in ab, a, and b represent microbial growth rate curves. I: Lag phase, II: Acceleration phase, III: Exponential phase, IV: Deceleration phase, V: Stationary phase. After the exponential phase, the deceleration phase continues until the stationary phase is reached. Au / MOF / K + The normalized apparent conductivity (NACV) values ​​of the microbial growth curves on the -ISM / PEP electrode are relatively small. These microbial growth kinetic data indicate that peptide incubation effectively inhibits microbial adhesion to the electrode surface and helps to delay microbial growth. Plate counting also verifies these conclusions, such as... Figure 5 cd. After incubation with the peptide, the number of colonies on the electrode surface was significantly reduced, indicating that the Y-type peptide can effectively inhibit the adhesion of microorganisms.

[0059] To verify the antibacterial activity of the Y-type peptide, Au / MOF / K was immersed in bacterial solution before testing. + -ISM / pep electrode and Au / MOF / K + - Fluorescence analysis was performed using an ISM electrode. For example... Figure 5 As shown in the figure, comparative analysis revealed a decrease in the number of viable bacteria after peptide incubation. Furthermore, more dead bacteria were observed on the electrode surface after peptide incubation, indicating that the Y-type peptide possesses antibacterial activity.

[0060] Example 4

[0061] In this embodiment, Au / MOF / K after peptide incubation was performed. + The effect of peptide introduction on detection performance in the -ISM / pep electrode was investigated, as follows: In 10 -10.5 -10 -3 Within the concentration range of M, for Au / MOF / K + -ISM / pep, Au / MOF / K + -ISM、Au / K + -ISM conducted Nernst response tests, such as Figure 6 As shown in figure a, the linear range of the ion-selective electrode without self-assembled Ni3(HITP)2 is 10. -6 -10 -3 M, the Nernst response slope is 55 ± 0.32 mV / dec. In contrast, the self-assembled Ni3(HITP)2 treated electrode exhibits a wider linear range of 10 -8 -10 -3 M, this is due to the enhanced interfacial ion-electron transfer resulting from the introduction of porous MOF materials. Furthermore, incubation with peptides did not significantly affect the Nernst response range of the electrode, with the detection limit decreasing from 1.26 × 10⁻⁶. -9 M increased slightly to 2.51 × 10 -9M. Experimental results show that the electrode maintained good detection performance after peptide incubation. For example... Figure 6 As shown in b, Au / K + The response time of -ISM ​​is 20-28 s, while the response time of the electrode prepared by the self-assembly of porous Ni3(HITP)2 is within 2-8 s, achieving a stable response potential. Furthermore, the peptide layer possesses wide ion transport channels, resulting in a large diffusion coefficient for ions within the peptide layer. Combining the advantages of MOF materials, a rapid response can be achieved.

[0062] Example 5

[0063] This embodiment focuses on Au / MOF / K + The stability and selectivity of the -ISM / PEP electrode were analyzed as follows: To investigate the short-term stability of the prepared ion-selective electrode, a current of ±1 nA was applied to the electrode to obtain chronopotential test results, such as... Figure 7 a. Determine Au / K according to the calculation formula ΔE / Δt. + -ISM, Au / MOF / K + -ISM / pep and Au / MOF / K + The short-term potential stability of the -ISM ​​is 702.8, 15.8, and 11.3 μV / s, respectively. Furthermore, based on the formula ΔE / Δt=I / Cf, where Cf is the low-frequency capacitance, Au / MOF / K is calculated. + -ISM / pep and Au / MOF / K + The Cf values ​​of -IS are 63.3 μF and 88.5 μF, respectively, which are much larger than those of the all-solid-state ISE based on MOF materials (1.4 μF). These results indicate that a potassium-ion selective electrode Ki can be constructed using porous MOF materials as a solid-state transduction layer. + -ISE exhibits the best short-term potential stability. This superior performance may be attributed to the excellent ion-electron transfer properties of porous MOFs.

[0064] The long-term stability of the prepared electrode was also investigated. It was continuously exposed to a bacterial suspension for different durations, and the changes in the Nernst slope were observed. Figure 7 As shown in b. It can be observed that within the 8-day testing period, Au / MOF / K + -The ISM / pep electrode exhibits a relatively stable potential response; compared to Au / MOF / K... + The response slope of the -ISM ​​electrode did not change significantly within 5 days of immersion, but after 6 days of immersion, the deviation from the theoretical value gradually increased with increasing immersion time. For the control electrode, a thicker biofilm formed on the electrode surface, thus affecting the response of the all-solid-state ion-selective electrode. Furthermore, the Au / MOF / K ratio was also investigated. +-Stability of the ISM / PEP electrode under light, O2, and CO2 conditions. For example... Figure 7 As shown in c, the prepared Au / MOF / K + -ISM / PEP electrodes are insensitive to light, O2, and CO2, but slight potential fluctuations can occur due to external interference such as airflow and external inductance. Furthermore, Au / MOF / K... + -ISM / pep electrodes exhibit good reproducibility and repeatability.

[0065] To evaluate the response of the ion-selective electrode in real samples, the Au / MOF / K ratio was investigated using a solution-separate method. + -ISM / pep and Au / MOF / K + -ISM in different cations (Cu 2+ Cd 2+ H + Na + Mg 2+ Ca 2+ Pb 2+ Zn 2+ K in solution + The selectivity. For example... Figure 7 As shown, the results confirm the excellent selectivity of the ion-selective electrode. In the presence of each potential interfering ion, the Au / MOF / K... + -ISM / pep selectivity coefficient and Au / MOF / K + The selectivity coefficients of the -ISMs are comparable, indicating that selectivity depends on the composition of the ion-selective membrane. Importantly, incubation with peptides does not adversely affect the selectivity of the ion-selective electrode.

[0066] Example 6

[0067] In this embodiment, the prepared Au / MOF / K + The application performance of the -ISM / PEP electrode was analyzed, specifically its ability to detect potassium ions in actual seawater. Three seawater samples were collected from different locations near the Qingdao coast and diluted. Au / MOF / K... + The potassium concentration in three water samples was determined using the ISM / PEP electrode direct measurement method and inductively coupled plasma atomic emission spectrometry (ICP-AES), as shown in Table 1. The results indicate that the potassium concentration in Au / MOF / K... + The -ISM / pep electrode exhibits excellent quantitative performance, consistent with potassium ion concentrations in diluted seawater samples determined by ICP-AES. Importantly, in real-world seawater environments, the peptide-incubated electrode demonstrates superior antifouling properties and more stable detection performance during long-term monitoring. These results ultimately validate the antifouling and bactericidal Au / MOF / K electrode developed in this study.+ -ISM / pep electrodes can be used to accurately determine the concentration of potassium ions in seawater.

[0068] Table 1. Determination of K in three diluted seawater samples from the Qingdao coast by direct potentiometry and ICP-AES. + concentration

[0069]

[0070] Note: a) Samples 1, 2, and 3 were diluted 10, 100, and 120 times respectively from samples collected in the coastal waters near Qingdao; b) Statistical parameters were obtained from three separate electrodes.

[0071] Therefore, this application provides an ion-selective electrode with antifouling and bactericidal functions, particularly suitable for the detection of potassium ions in complex seawater. Specifically, a conductive porous MOF with a high specific surface area is selected as the solid-state transconducting layer, which helps the ion-selective electrode to perform ion-electron transfer more quickly. Simultaneously, a Y-type peptide is used to modify the electrode. Due to its hydrophilicity and near-neutral charge in the marine environment, it can effectively remove bacteria from the electrode surface and effectively inhibit the adhesion of bacteria and other organisms. Real-time analysis of microbial growth kinetics on different electrode surfaces was performed using a microbial growth analyzer. Theoretical calculations and experimental results show that the introduction of the peptide improves the antifouling performance of the electrode without affecting its detection performance. The prepared antifouling potassium ion-selective electrode exhibits a Nernst response range of 10⁻⁶. -8 ~10 -3 M, detection limit is 2.51×10 -9 The prepared potassium ion selective electrode maintained a good Nernst response slope during the 8-day bacterial culture environment test and a good potential response during long-term testing. Furthermore, the prepared electrode maintained excellent antifouling and detection capabilities in real seawater. Therefore, the construction of an antifouling ion selective electrode based on conductive MOF materials and Y-type peptide modification has good feasibility and operational prospects in real marine environments, especially for long-term application in seawater.

[0072] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0073] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A Y-type polypeptide-modified ion-selective electrode, characterized in that, The electrode base, the solid-state transduction layer, the ion-selective membrane, and the anti-fouling and anti-bacterial layer, the solid-state transduction layer is self-assembled on the electrode base, the solid-state transduction layer is a conductive porous metal organic framework material, the ion-selective membrane is arranged on the solid-state transduction layer, the anti-fouling and anti-bacterial layer is arranged on the surface of the ion-selective membrane, the anti-fouling and anti-bacterial layer is a Y-type polypeptide, the Y-type polypeptide includes a resistance chain, an anti-bacterial chain, and an adhesive amino acid, and the sequence is DOPA-K(RWRWRW-)EKEKEKEK.

2. The Y-type polypeptide-modified ion-selective electrode according to claim 1, wherein, The electrode base adopts a gold electrode; the solid-state transduction layer adopts Ni3(HITP)2 as the MOF material; and the ion-selective membrane is one of a potassium ion-selective membrane, a calcium ion-selective membrane, a magnesium ion-selective membrane, a lead ion-selective membrane, a copper ion-selective membrane, and a sodium ion-selective membrane.

3. A method for the preparation of a Y-type polypeptide-modified ion-selective electrode according to claim 1 or 2, characterized in that, The method includes the following steps: Step one, pretreatment of the electrode base; the electrode base is used after being cleaned, polished, and activated; Step two, preparation of the MOF material; the pretreated electrode base in step one is placed in a flask, a conductive porous MOF material is used as the solid-state transduction layer, a self-assembly process is performed on the electrode base, and an electrode base with a self-assembled solid-state transduction layer is obtained; Step three, preparation of the ion-selective membrane; an ion-selective membrane solution is configured, the ion-selective membrane solution is added dropwise on the self-assembled solid-state transduction layer obtained in step two, and an ion-selective membrane is formed thereon; The prepared electrode is denoted as Au / MOF / ISM; Step four, preparation of the ion-selective electrode; an anti-fouling and anti-bacterial layer is arranged on the ion-selective membrane formed in step three, and a final ion-selective electrode is obtained, and the prepared electrode is denoted as Au / MOF / ISM / pep.

4. The method for preparing a Y-type polypeptide-modified ion-selective electrode according to claim 3, wherein the Y-type polypeptide-modified ion-selective electrode is prepared by the steps of: The electrode base in step one adopts a gold electrode, and the pretreatment includes the following steps: S1, the gold electrode is cleaned with ultrasonic ultrapure water for 10 minutes and dried with nitrogen; S2, the electrode was cycled in a 100 mmol L -1 solution of sodium hydroxide at a rate of 0.1 V s -1 over a potential range of -0.5 to 1.5 V for 100 cycles; S3, the gold electrode is precisely polished on a special polishing cloth using 0.3 μm and 0.05 μm aluminum oxide polishing powder; after polishing, the electrode is cleaned by ultrasonic ultrapure water treatment; S4, the electrode is soaked in a mixed aqueous solution containing 30wt% H2SO4 and 30wt% H2O2 for 15-20 minutes, and the volume ratio of the H2SO4 and H2O2 solution is 3:1; S5, the electrode was cycled in a 100 mmol L -1 solution of H2SO4 with a potential range of -0.2-1.5 V at a cyclic scan rate of 0.1 V s -1 for 25 cycles; after activation, the electrode was thoroughly rinsed with ultrapure water and stored for later use.

5. The method for preparing the Y-type polypeptide-modified ion-selective electrode according to claim 3, characterized in that, In step two, Ni3(HITP)2 is used as the MOF material, and the preparation process of Ni3(HITP)2 includes the following steps: A solution was prepared by dissolving 20.85 mg of nickel acetate tetrahydrate in 9 mL of dimethyl sulfoxide, sonicating for 2 min, and then preheating to 65 °C. Then, 30 mg of HATP-6HCl solution was added to 9 mL of ultrapure water and stirred until the solution was uniform. Then, 12 mL of 4 mol L -1 A solution was prepared by dissolving 20.85 mg of nickel acetate tetrahydrate in 9 mL of dimethyl sulfoxide, sonicating for 2 min, and then preheating to 65 °C. Then, 30 mg of HATP-6HCl solution was added to 9 mL of ultrapure water and stirred until the solution was uniform. Then, 12 mL of 4 mol L -1 An aqueous NaOAc solution was prepared by dissolving 0.5 g of NaOAc in 100 mL of ultrapure water. A solution was prepared by dissolving 20.85 mg of nickel acetate tetrahydrate in 9 mL of dimethyl sulfoxide, sonicating for 2 min, and then preheating to 65 °C. Then, 30 mg of HATP-6HCl solution was added to 9 mL of ultrapure water and stirred until the solution was uniform. Then, 12 mL of 4 mol L -1 An aqueous NaOAc solution was prepared by dissolving 0.5 g of NaOAc in 100 mL of ultrapure water. A 6. The method for preparing the Y-type polypeptide-modified ion-selective electrode according to claim 3, characterized in that, In step three, the ion-selective membrane adopts a potassium ion-selective membrane, and the preparation process includes the following steps: A potassium ion selective membrane solution was formed by dissolving 4 mg valinomycin, 1 mg NaTFPB, 65.4 mg PVC and 143.4 μL DOS in 1500 μL THF; 80 μL of the potassium ion selective membrane solution was added on the self-assembled MOF material on the surface of the gold electrode and left overnight; the membrane was naturally dried at room temperature; the prepared electrode was recorded as Au / MOF / K + - ISM.

7. The method for preparing the Y-type polypeptide-modified ion-selective electrode according to claim 3, characterized in that, In step four, the ion-selective electrode adopts a potassium ion-selective electrode, and the preparation process includes the following steps: In the surface of the potassium ion-selective membrane 10 μL of 0.2 mg mL -1 of Y-type polypeptide were incubated for 4 h; the electrode thus obtained was denoted Au / MOF / K + - ISM / pep.

8. Application of the Y-type polypeptide modified ion-selective electrode according to claim 1 or 2 in detection of seawater potassium ions, calcium ions, magnesium ions, lead ions, copper ions, or sodium ions.

9. Use according to claim 8, characterized in that, The Nernst response range of the ion-selective electrode is 10 -8 -10 -3 M, with a detection limit of 2.51 x 10 -9 M and a response time of 2-8 s.

Images