A 4-APM / Zr-MOF / PET nanochannel sensor based on spatial modification and a preparation method and application thereof

Abstract

The application discloses a kind of 4-APM / Zr-MOF / PET nanochannel sensors based on space modification and its preparation method and application, belong to sensor preparation technical field.The sensor includes PET film, Zr-MOF and probe 4-APM;The PET film is etched with bullet type nanochannel structure;Zr-MOF is modified in the bullet type nanochannel structure of PET film by complexation, and the probe 4-APM is modified on Zr-MOF by coupling.The sensor of the application utilizes the characteristics of large specific surface area and porous structure of MOFs, making it a probe fixed substrate, and cooperates with functional probe 4-APM and special nanochannel structure, based on the complexation reaction of 4-APM and Con A amplifies current signal change, realizes the rapid and stable detection of Con A.

Description

Technical Field

[0001] This invention belongs to the field of sensor fabrication technology, specifically relating to a 4-APM / Zr-MOF / PET nanopore sensor based on spatial modification, its fabrication method, and its application. Background Technology

[0002] Lectins are a class of proteins that can specifically recognize and reversibly bind to carbohydrate compounds. They are widely found in plants, invertebrates, and higher animals, playing important roles in various biological processes such as cell recognition, signal transduction, and immune responses. Concanavalin A (Con A) is a typical plant lectin isolated and purified from canavalia seeds. Its sugar-binding activity is strictly dependent on calcium. 2+ and Mn 2+ The presence of metal ions exhibits a clear metal ion-dependent characteristic.

[0003] As a biologically active protein, Con A exhibits significant cytotoxicity even at low concentrations, posing a potential threat to human health. Oral ingestion of Con A can irritate the gastrointestinal mucosa, causing acute poisoning symptoms such as nausea, vomiting, abdominal pain, and diarrhea. High-dose exposure can interfere with lymphocyte activation and proliferation by binding to glucose receptors on the surface of immune cells, affecting the normal regulation of the body's immune function. However, Con A's specific recognition ability of carbohydrate molecules also makes it an indispensable tool protein in glycobiology research, widely used in biomedical detection fields such as cell membrane glycosylation analysis, glycoprotein isolation and purification, and targeted drug delivery.

[0004] Given the significant application value of Con A, establishing efficient and reliable Con A detection methods is of great practical importance. Currently, various analytical techniques have been reported for the quantitative detection of Con A, mainly including enzyme-linked immunosorbent assay (ELISA) based on antigen-antibody specific recognition, electrochemiluminescence based on electrochemical reactions, highly sensitive resonance Rayleigh scattering spectroscopy, label-free surface plasmon resonance sensing, electrochemical impedance spectroscopy for real-time monitoring of interfacial changes, flexible fluorescence sensing strategies, and various electrochemical analytical methods. These methods have achieved effective detection of Con A to varying degrees, providing technical support for related research and applications.

[0005] However, existing detection technologies still suffer from several common limitations: some methods involve complex detection systems, relying on sophisticated instruments and skilled operators, thus restricting their widespread application; sensor interfaces lack stability and are susceptible to interference from complex matrices, affecting the accuracy and reproducibility of detection results; most methods require fluorescent or electrochemical labeling of probe molecules, a cumbersome process that may affect the native conformation and biological activity of Con A; and response times are generally long, making it difficult to meet the practical needs of rapid detection. These technical bottlenecks, to some extent, restrict the practical application of Con A detection methods in fields such as food safety monitoring and environmental monitoring.

[0006] Therefore, developing a novel Con A detection method that is easy to operate, has a fast response, high stability, and excellent sensitivity, in order to address the shortcomings of existing methods, remains an important issue that urgently needs to be addressed in the fields of analytical chemistry and biosensing. This method has significant theoretical research value and broad application prospects. Summary of the Invention

[0007] To address the shortcomings of existing methods for detecting Con A, the first objective of this invention is to provide a spatially modified 4-APM / Zr-MOF / PET nanopore sensor. By fixing the probe 4-APM (4-aminophenyl-α-D-mannopyranoside) within the special pore structure of a PET membrane using Zr-MOF, more detection active sites can be provided, and the detection signal can be amplified.

[0008] The second objective of this invention is to provide a method for preparing a 4-APM / Zr-MOF / PET nanopore sensor based on spatial modification. By growing PET film and Zr-MOF in situ, the two materials are tightly bonded together, and the probe 4-APM is modified by chemical grafting. This method has the advantages of simple preparation method and high reliability.

[0009] The third objective of this invention is to provide an application of a spatially modified 4-APM / Zr-MOF / PET nanopore sensor, which, when applied to the detection of concanavalin A, has advantages such as high selectivity, high detection sensitivity, and stable sensing system.

[0010] To achieve the above-mentioned technical objectives, the present invention provides a space-modified 4-APM / Zr-MOF / PET nanopore sensor, the material comprising a PET film, Zr-MOF, and a probe 4-APM; the PET film is etched with a bullet-shaped nanopore structure; the Zr-MOF is complexed and modified in the bullet-shaped nanopore structure of the PET film, and the probe 4-APM is coupled and modified on the Zr-MOF; wherein, 4-APM is 4-aminophenyl-α-D-mannopyranoside.

[0011] In the technical solution of this invention, the combination of the sensor's unique morphology and the probe is key to achieving excellent selectivity, sensitivity, and detection stability. Specifically, this invention utilizes the large specific surface area, porous structure, and good stability of Zr-MOF, using it as a probe matrix for stereotactic modification within PET nanopores. Compared to planar modification, stereotactic modification provides more active sites for probe fixation within the nanopores, significantly increasing the binding probability of Con A and 4-APM, and enhancing the robustness of the modified layer through the coordination effect of the metal-organic framework. Furthermore, the probe 4-APM is covalently grafted and uniformly distributed on the Zr-MOF within the pores. Its mannose groups can specifically recognize target molecules. This recognition process occurs within a confined space at the nanoscale, resulting in a volume effect. The asymmetric bullet-shaped nanopore structure amplifies the ion current signal, enabling highly selective quantitative detection of the target analyte. Moreover, the stereotactic modification structure improves the sensor's anti-interference capability and long-term stability.

[0012] Further preferred, when the bullet-shaped nanopore structure is a single bullet-shaped nanopore structure, the sensor's signal response performance is even better.

[0013] This invention also provides a method for fabricating a 4-APM / Zr-MOF / PET nanopore sensor based on spatial modification, the method comprising the following steps:

[0014] After S1 PET film is bombarded with heavy ions to form tracks and activated, it is placed in an alkaline solution containing surfactant for asymmetric etching to obtain a PET film with bullet-shaped nanopore structure.

[0015] S2 The PET membrane with bullet-shaped nanopore structure is mixed with zirconium salt, amino-containing organic ligand, organic solvent and morphology modifier and then subjected to in-situ growth reaction to obtain Zr-MOF / PET composite material;

[0016] S3 The Zr-MOF / PET composite material is activated with glutaraldehyde and then impregnated in 4-APM solution, followed by a coupling reaction to obtain the final product.

[0017] The present invention mainly utilizes Zr after forming a PET film with a bullet-shaped nanopore structure. 4+The complexation reaction with carboxyl groups on the PET film enables the steric growth of Zr-MOF within the PET nanopores. Then, utilizing the amino groups on Zr-MOF and 4-APM, a coupling reaction is used to couple the probe 4-APM onto the Zr-MOF. In the alkaline etching process of PET nanopores, simple alkaline etching typically proceeds uniformly along the inner wall of the pores, easily producing symmetrical, iso-diameter pore structures. This is because alkaline molecules diffuse freely, and the dissolution reaction occurs almost simultaneously across the entire pore wall, lacking directional control. However, this invention adds a surfactant to the alkaline solution. The surfactant molecules selectively adsorb onto certain areas of the pore wall (such as the pore opening or bottom) to protect them from etching, altering the local surface energy and chemical reactivity, resulting in different etching rates at different locations. Simultaneously, the surfactant alters the wettability and forces of the liquid within the pores, creating a gradient concentration or flow difference in the alkaline solution, thereby producing asymmetric etching in the longitudinal direction and forming a unique bullet-shaped nanopore structure.

[0018] Furthermore, during the in-situ growth process of this invention, MOF precursor molecules directly aggregate and crystallize within the pores, enabling the uniform formation of thin films or nanocrystalline layers along the pore walls. The in-situ grown MOF material not only achieves a more stable bond with the PET pore walls, but also produces smaller and more uniformly distributed MOF nanocrystals, ensuring pore permeability. In contrast, directly adding Zr-MOF particles can easily lead to problems such as pore blockage or uneven pore wall coverage due to the large size or uneven dispersion of the Zr-MOF particles, which may prevent complete entry into the pores.

[0019] As a preferred embodiment, the heavy ions include, but are not limited to, Xe. When forming a multi-bullet nanoporous structure, multiple heavy ions are used to bombard the nanoporous structure to form multiple tracks; conversely, when forming a single-bullet nanoporous structure, heavy ion bombardment is used to form a single track.

[0020] As a preferred approach, the amino-containing organic ligand, organic solvent, and morphology modifier can be mixed evenly first, and then the PET membrane with bullet-shaped nanopore structure can be fixed and supported by a tetrafluoroethylene scaffold and placed in the Zr-MOF mixed solution for in-situ growth reaction.

[0021] As a preferred embodiment, in S1, the activation treatment involves irradiating one side of the PET film with a UV lamp for 10-12 hours; the surfactant in the surfactant-containing alkaline solution includes anionic surfactants, such as sodium dodecyl diphenyl ether disulfonate; the concentration of the alkaline solution in the surfactant-containing alkaline solution is 5-6 mol / L; and the temperature of the asymmetric etching is 50-60°C. Within the relatively high alkaline concentration and asymmetric etching temperature range of this invention, the single-bullet-shaped nanopore structure can be better guaranteed to be a through-hole. Furthermore, this invention uses single-sided UV irradiation during the irradiation process. The UV pretreatment destroys the cross-linked structure of the track portion under light, thereby significantly increasing the track etching rate, while the increase in the bulk etching rate is relatively limited. This makes it easier for etching to penetrate from one side and form a high aspect ratio pore shape.

[0022] In this invention, the etching time is not specifically limited, as long as it can be etched to form a through-hole single bullet-shaped nanopore structure.

[0023] As a preferred embodiment, the mass fraction of the surfactant in the alkaline solution containing the surfactant is 0.05~0.1%. During the alkaline etching process of PET nanopores, the amount of surfactant directly affects the pore morphology and etching effect. If the amount of surfactant is too low, the adsorption effect is insufficient, and the etching remains predominantly symmetrical, making it difficult to form the ideal bullet-shaped nanopore structure. Conversely, if the amount of surfactant is excessive, a large number of surfactant molecules easily remain on the inner wall of the nanopores or the membrane surface, which is difficult to remove through conventional cleaning. These residues will occupy some of the active sites for subsequent Zr-MOF in-situ growth.

[0024] As a preferred embodiment, in S2, the zirconium salt is at least one of zirconium chloride and zirconium oxychloride octahydrate; the amino-containing organic ligand includes 2-amino-4,4'-biphenyl dicarboxylic acid (BPDC-NH2); the organic solvent is at least one of N,N-dimethylformamide (DMF), N,N-diethylformamide, and tetrahydrofuran; the morphology modifier is at least one of formic acid and acetic acid; and the in-situ growth reaction is carried out at a temperature of 100~120℃ for 12~24h. More preferably, the temperature is 120℃ and the time is 20~24h.

[0025] As a preferred embodiment, in the in-situ growth reaction, the mass ratio of zirconium salt, amino-containing organic ligand, organic solvent, and morphology modifier is (0.48~0.5):(0.26~0.28):(28~31):(3.5~3.8). Within the mass ratio range of this invention, the synthesis of Zr-MOF materials with regular morphology can be guaranteed, and suitable Zr-MOF materials can be grown in situ within the pore structure of the PET membrane without clogging the pores. In the in-situ growth reaction of this invention, since the PET membrane with bullet-shaped nanopore structure only serves as a carrier for the sensor, its mass is not limited.

[0026] As a preferred embodiment, in S3, the activation conditions for glutaraldehyde are: a glutaraldehyde concentration of 2-3 wt%, a temperature of 4-10 °C, and a time of 6-10 h; the concentration of the 4-APM solution is 0.1-0.5 μg / mL, and the coupling reaction time is 20-24 h. Within the preferred concentration ranges of glutaraldehyde and 4-APM solution in this invention, more 4-APM probes can be grafted to achieve selective adsorption of Con A.

[0027] This invention utilizes the active aldehyde groups at both ends of the glutaraldehyde molecule as a bridge to connect the amino groups on Zr-MOF and 4-APM, thereby coupling and fixing the probe 4-APM onto Zr-MOF in the porous structure.

[0028] Furthermore, the Zr-MOF / PET composite material was fixed in an electrolytic cell, and both sides were soaked in glutaraldehyde solution. Then, probe 4-APM solution was placed in the electrolytic cells at both ends for soaking.

[0029] Finally, this invention also provides an application of a spatially modified 4-APM / Zr-MOF / PET nanopore sensor for the detection of concanavalin A.

[0030] The sensor of this invention can achieve highly selective and sensitive detection of concanavalin A. The principle is that the probe 4-APM in the sensor can selectively complex with Con A, producing a volume effect that causes K in the electrolyte to... + Cl - The transmembrane current generated by plasma transport changes, which in turn alters the ion current signal within the nanochannel, resulting in a significant change in conductivity. This enables rapid, simple, stable, and low-cost detection of Con A.

[0031] As a preferred embodiment, the specific detection process is as follows: electrochemical detection is performed using a 4-APM / Zr-MOF / PET nanopore sensor with conductivity detection method; a linear fitting curve is established between the conductivity of the sensor after reacting with concanavalin A and the concentration of concanavalin A; and the concentration of concanavalin A in the test solution is obtained by calculating through the linear fitting curve.

[0032] Furthermore, the present invention provides a spatially modified 4-APM / Zr-MOF / PET nanopore sensor for detecting concanavalin A, the process of which is as follows:

[0033] S1 The 4-APM / Zr-MOF / PET nanoporous sensor was placed in a solution containing Con A to carry out a complexation reaction, and a linear fitting curve of the conductivity after the complexation reaction and the Con A concentration was established.

[0034] S2 replaces the solution containing Con A with the test solution, measures the conductivity after the complexation reaction, and then substitutes the result into the linear fitting curve to calculate the concentration of Con A in the test solution.

[0035] As a preferred embodiment, the concentration of Con A is 10. -7 ~10 -12 M; the linear fitting curve is y = 41.68 - 1.84x, where y is the conductivity after the complexation reaction and x is the concentration of Con A.

[0036] As a preferred embodiment, the complexation reaction takes 3 to 12 minutes. More preferably, it takes 6 to 9 minutes.

[0037] As a preferred approach, the selectivity and anti-interference ability of the 4-APM / Zr-MOF / PET nanopore analytical sensing platform were tested using control samples of other amino acids at 1000-fold concentrations. To more clearly illustrate the difference in selectivity and anti-interference ability, this invention compared the conductivity ratio before and after the reaction, expressed by the following formula:

[0038] G i =G / G 0；

[0039] Where G is the conductivity before detection, G0 is the conductivity after detection, and G i It is the ratio of conductivity before and after the reaction.

[0040] In this invention, the ratio of conductivity before and after the complexation reaction is obtained by measuring the voltage from -60mV to +60mV, recording the corresponding current magnitude for every 10mV, plotting an IV curve, and calculating the slope of the curve.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) This invention utilizes the large specific surface area, porous structure, and good stability of Zr-MOF to stereo-modify the probe matrix within PET nanopores. Compared to planar modification, stereo-modification provides more active sites for probe fixation within the nanopores, significantly increasing the binding probability of Con A and 4-APM. It also enhances the robustness of the modified layer through the coordination of the metal-organic framework. Furthermore, the probe 4-APM is covalently grafted and uniformly distributed on the Zr-MOF within the pores. Its mannose groups can specifically recognize target molecules. This recognition process occurs within a confined space at the nanoscale, resulting in a volume effect. The asymmetric single-bullet-shaped nanopore structure amplifies the ion current signal, enabling highly selective quantitative detection of the target analyte. Moreover, the stereo-modified structure improves the sensor's anti-interference capability and long-term stability.

[0043] (2) The method of the present invention achieves quantitative detection of Con A by detecting the conductivity after complexation reaction, and has good selectivity and high sensitivity.

[0044] (3) The nanopore sensor prepared by the present invention using PET as a substrate is covered with a large number of carboxyl groups, which facilitates the fixation of various identification elements. Furthermore, due to the good thermal stability and flexibility of PET material, the PET nanopore sensor has great potential in the field of wearable sensing devices.

[0045] (4) The preparation method of the present invention achieves a tight bond between the two materials by in-situ growth of PET film and Zr-MOF, and by chemically grafting and modifying probe 4-APM, which has the advantages of simple preparation method and high reliability. Attached Figure Description

[0046] Figure 1 This is a schematic diagram illustrating the fabrication process of the 4-APM / Zr-MOF / PET nanopore sensor of the present invention and its selective detection of Con A.

[0047] Figure 2 The images show cross-sectional SEM images of the PET membrane with a single-bullet-shaped nanoporous structure prepared in Example 1 and the Zr-MOF / PET composite material prepared in Example 1. Specifically, (a) is a cross-sectional SEM image of the PET membrane with a single-bullet-shaped nanoporous structure prepared in Example 1; and (b) is a cross-sectional SEM image of the Zr-MOF / PET composite material prepared in Example 1.

[0048] Figure 3SEM images of the front, back, and cross-section of the cylindrical hole material prepared in Comparative Example 1, as well as the IV curve of the cylindrical hole material in its bare hole state. Among them, (a) is the SEM image of the front of the cylindrical hole material prepared in Comparative Example 1; (b) is the SEM image of the back of the cylindrical hole material prepared in Comparative Example 1; (c) is the SEM image of the cross-section of the cylindrical hole material prepared in Comparative Example 1; and (d) is the IV curve of the cylindrical hole material prepared in Comparative Example 1 in its bare hole state.

[0049] Figure 4 This is a comparison chart of the conductivity ratios of materials before and after the reaction under different Zr-MOF in-situ growth times in Example 2 of the present invention.

[0050] Figure 5 This is a comparison chart of the conductivity ratio of materials before and after the reaction at different complexation reaction times in Example 3 of the present invention.

[0051] Figure 6 The image shows the IV curves and corresponding conductivity changes of the 4-APM / Zr-MOF / PET nanoporous sensor used in Example 1 before and after detecting Con A. Specifically, (a) shows the IV curves of the 4-APM / Zr-MOF / PET nanoporous sensor used in Example 1 before and after detecting Con A; and (b) shows the corresponding conductivity changes.

[0052] Figure 7 The images show the response curves of the 4-APM / Zr-MOF / PET nanoporous sensor in Example 1 for detecting different concentrations of Con A, and the corresponding linear fitting curves of conductivity and concentration. Specifically, (a) shows the response curves of the 4-APM / Zr-MOF / PET nanoporous sensor in Example 1 for detecting different concentrations of Con A, and (b) shows the corresponding linear fitting curves.

[0053] Figure 8 The 4-APM / Zr-MOF / PET nanopore sensor prepared in Example 1 exhibits selectivity for Con A and different amino acids and proteins.

[0054] Figure 9 The 4-APM / Zr-MOF / PET nanopore sensor prepared in Example 1 exhibits resistance to interference from Con A and various amino acids and proteins. Detailed Implementation

[0055] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments. Obviously, the embodiments described below are only a part of the embodiments, and all other embodiments obtained by those skilled in the art without creative effort are still within the scope of protection of the present invention.

[0056] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0057] The polyethylene terephthalate (PET) film (13 μm thick, biaxially oriented) used in the embodiments and comparative examples of this invention was purchased from Goodfellow GmbH, Germany; the Ag / AgCl electrode was purchased from Shanghai Xianren Instrument Co., Ltd.; the experimental water was ultrapure water (resistivity ≥ 18.3 MΩ·cm); all reagents used were analytical grade (AR), and the descriptions of amino acids in the following descriptions are all abbreviated in English.

[0058] Example 1

[0059] 1. Fabrication of 4-APM / Zr-MOF / PET nanoporous sensors

[0060] (1) Bullet-shaped nanopores were prepared by ion track etching, using heavy ions Xe (8.98 MeVu) -1 A PET film with a single track was obtained by bombarding it. One side of the PET film was then activated by irradiating it with a 312 nm UV lamp for 12 hours. Subsequently, the activated PET film was subjected to asymmetric chemical etching at a constant temperature of 60 °C for 7 minutes using a 50 ml 6 mol / L NaOH solution containing 0.05% (mass fraction) sodium dodecyl diphenyl ether disulfonate. After etching, the PET film surface was washed with ultrapure water and allowed to stand overnight for later use, resulting in a PET film with a single bullet-shaped nanoporous structure containing through-holes.

[0061] (2) Using Zr 4+ Zr-MOF / PET composite material was prepared by complexing carboxyl groups on a PET membrane with a mono-bullet nanoporous structure: 0.488 g of ZrCl4 and 0.267 g of BPDC-NH2 were ultrasonically dissolved in 30 mL of DMF, and then 3.6 mL of acetic acid was added dropwise and the mixture was shaken for 30 min. The mixture was transferred to a 100 mL polytetrafluoroethylene-lined reactor. A clean and dry PET membrane with a mono-bullet nanoporous structure was fixed and supported in the mixture in the reactor using a polytetrafluoroethylene support. The mixture was placed in a drying oven at 120 °C for 24 h. After the system cooled to room temperature, it was removed and cleaned three times with DMF and methanol to remove surface impurities. After air drying, the Zr-MOF / PET composite material was obtained. A 1 M KCl (pH=7.4) electrolyte was placed in the dispersion tanks on both sides of the Zr-MOF / PET composite material, and the current-voltage (IV) curve was measured to detect whether Zr-MOF was successfully modified into the mono-bullet nanoporous space.

[0062] (3) A 4-APM / Zr-MOF / PET nanoporous sensor was prepared by chemical modification. Since both the probe 4-APM and the substrate Zr-MOF contain amino groups, 4-APM can be linked to Zr-MOF by glutaraldehyde coupling. The specific operation is as follows: 2 mL of 2.5 wt% glutaraldehyde (GA) solution was placed in the dispersion tanks on both sides of the Zr-MOF / PET composite material and activated at 4 °C for 6 h. After activation, the solution was aspirated and rinsed with ultrapure water. Subsequently, 2 mL of 4-APM probe solution with a concentration of 0.1 μg / mL was added to the dispersion tanks on both sides of the Zr-MOF / PET composite material and soaked for 24 h (4 °C). After activation, the probe solution was aspirated and rinsed with ultrapure water for later use, thus obtaining the 4-APM / Zr-MOF / PET nanoporous sensor. Subsequently, 1M KCl (pH=7.4) electrolyte was added to the dispersion tanks on both sides of the 4-APM / Zr-MOF / PET nanoporous sensor, and the IV curve was measured to detect whether the 4-APM was successfully modified.

[0063] The morphology of the monolithic bullet-shaped nanoporous PET film and the Zr-MOF / PET composite material was analyzed using scanning electron microscopy. The results are as follows: Figure 2 As shown. Figure 2 The cross-sectional view in (a) shows that the apertures at both ends are asymmetrical, with pointed round ends and a cylindrical shape in the middle section, indicating that the present invention has successfully prepared a single bullet-shaped channel structure, which is a through-hole structure. Figure 2 As can be seen in (b) of the invention, in the Zr-MOF / PET composite material, the MOF material is successfully modified inside the pores, presenting a three-dimensional spatial structure, and the Zr-MOF prepared by the method of the present invention has a regular octahedral structure.

[0064] 2. Feasibility of using a 4-APM / Zr-MOF / PET nanoporous sensor for Con A detection

[0065] When detecting Con A, the concanavalin A solution (concentration of 10) was used. -9 M) was mixed with an equal concentration of 4-APM solution and added to one side of the sensor. A bias voltage of 0.5V was applied for 3 min to promote multivalent binding between molecules. The sensor was then thoroughly rinsed with ultrapure water and 1M KCl electrolyte to remove non-specifically adsorbed substances. Finally, the conductivity of the nanopores was recorded in fresh 1M KCl electrolyte.

[0066] Depend on Figure 6As shown in (a) of the figure, the current at -1V is significantly greater than that at +1V in the bare pore state, indicating that the current asymmetry is consistent with the asymmetric characteristics of the bullet-shaped nanochannel. Subsequently, modification of Zr-MOF (i.e., UiO-67-NH2 in the figure) alters the effective size within the pore, thereby hindering the output of the ion signal. Its ion current and conductivity also decrease sharply, providing preliminary evidence for the successful modification of Zr-MOF on the inner surface of the pore.

[0067] Furthermore, the modified IV curve of 4-APM (i.e., 4-APM in the figure) produces a significantly higher current response signal than the bare via state. Its conductivity ratio results are as follows: Figure 6 As shown in (b), after Con A combines with 4-APM, it occupies the effective space of the pores, reducing the pore size of the PET film and thus decreasing the conductivity within the pores.

[0068] 3. Performance of 4-APM / Zr-MOF / PET nanoporous sensor for Con A detection and analysis

[0069] A series of concentrations from 0 M to 10 M were prepared. -12 A Con A solution of M was added to a 1M KCl electrolyte at pH 7.4 to incubate the sensor. The 4-APM / Zr-MOF / PET nanoporous sensor was used to quantitatively analyze Con A, and its IV curve was measured and the corresponding conductivity was calculated.

[0070] like Figure 7 As shown in curve (a) of Figure 1, the current at -1V increases in absolute value with increasing Con A concentration, further affecting its corresponding conductivity. With concentration increasing from 10... -6 M decreased to 10 -12 M, the absolute value of the current in each concentration group increases overall, indicating that the concentration directly affects the conductivity of the sample. After dextran binds with Con A, it occupies the effective size of the nanopores, which reduces the ion current and conductivity in the pores. The more the pore size is occupied, the lower the conductivity becomes.

[0071] Depend on Figure 7 As shown in (b), the linear fitting curve of the relationship between conductivity and concentration (y=41.68-1.84x, R) 2 In (=0.99329), R 2 Approaching 1, in 10 -12 M to 10 -7In the M concentration range, conductivity exhibits a highly linear correlation with the logarithm of concentration. This linear relationship provides a reliable model for quantitative concentration detection, indicating that the system can stably convert concentration signals into conductivity responses. Furthermore, the detection limit of the nanopore detection method is 2.41 pM, signifying exceptional sensitivity and effective response capability for ultra-trace to trace concentrations.

[0072] 4. Selectivity of 4-APM / Zr-MOF / PET nanoporous sensor for Con A

[0073] Cysteine ​​(L-Cys), glutamic acid (Glu), arginine (Arg), and bovine serum albumin (BSA) were selected as controls in the experiment. The concentration of Con A was 1 μmol / L, and the concentration of the other controls was 1 mmol / L. The solution before detection was used as a blank control group. To test the anti-interference ability, the control solutions were added to the dispersion tank on one side of the 4-APM / Zr-MOF / PET nanoporous sensor and reacted for three minutes. The control solutions were then aspirated and washed three or more times with ultrapure water and electrolyte, with the electrolyte replaced with fresh electrolyte. The conductivity was then measured.

[0074] Experimental results are as follows Figure 8 As shown, only when Con A binds to 4-APM within the pores does the pore conductivity decrease significantly, while the other control substances show almost no reaction, with no significant difference in conductivity. These experimental results demonstrate that the 4-APM / Zr-MOF / PET nanoporous sensor exhibits excellent selectivity for Con A.

[0075] 5. The anti-interference performance of the 4-APM / Zr-MOF / PET nanopore sensor against Con A

[0076] Cysteine ​​(Cys), glutamic acid (Glu), arginine (Arg), and bovine serum albumin (BSA) were selected as interfering agents in the experiment. The interfering agents were mixed separately with Con A solution, and simultaneously all interfering agents were mixed with Con A solution to obtain a mixed group. The concentration of Con A in the experiment was 1 μmol / L, and the concentration of the other interfering agents was 1 mmol / L. The control group served as a blank control. To test the anti-interference ability, the mixed solution of interfering agents and Con A was reacted in the dispersion tank on one side of the 4-APM / Zr-MOF / PET nanoporous sensor for three minutes. The control solution was then aspirated and washed three or more times with ultrapure water and electrolyte, with a fresh electrolyte added. The conductivity was then measured.

[0077] Experimental results are as follows Figure 9As shown, the pore conductivity decreased significantly, indicating that the interfering substances in the mixed solution mainly consisted of Con A binding with 4-APM within the pores, while the influence of other interfering substances was minimal. These experimental results demonstrate that the 4-APM / Zr-MOF / PET nanoporous sensor exhibits excellent anti-interference properties against Con A.

[0078] Example 2

[0079] This embodiment investigated the effect of Zr-MOF growth within bullet-shaped nanopores of PET membranes on ion current signals under different in-situ growth times. The only difference between this embodiment and Example 1 was that the in-situ growth time was replaced with 12h, 16h, 20h, and 24h, respectively; all other steps and conditions remained the same. The change in the conductivity ratio of the material before and after the in-situ reaction was measured, and the results are as follows: Figure 4 As shown.

[0080] Depend on Figure 4 The results show that when the growth time is 12 h, the Zr-MOF deposition within the pores is insufficient, resulting in low pore wall coverage and fewer subsequent probe fixation sites, leading to insignificant changes in the current signal. As the growth time is extended to 16–24 h, Zr-MOF forms a uniform and dense three-dimensional modified layer, the effective inner diameter of the pores is moderately reduced, and the ion current response is significant and stable. However, if the growth time exceeds 24 h, the PET film will be damaged. Therefore, the preferred in-situ growth time is 24 h, at which point the optimal balance between loading and pore permeability can be achieved.

[0081] Example 3

[0082] This embodiment investigated the effect of the complexation reaction time between the 4-APM probe and ConA after glutaraldehyde activation on sensor performance under different complexation reaction times. The only difference between this embodiment and Example 1 is that the complexation reaction time was replaced with 3 min, 6 min, 9 min, and 12 min, respectively; all other steps and conditions remained the same. The change in the conductivity ratio of the materials before and after the complexation reaction was measured, and the results are as follows: Figure 5 As shown.

[0083] Depend on Figure 5 As can be seen, when the complexation reaction time is less than 3 minutes, most of the ConA has not yet bound, resulting in a weak current signal and poor sensitivity. When the reaction time reaches 6-9 minutes, the sensor's response signal to ConA is the strongest and most stable. Further extending the reaction time to 12 minutes, the signal no longer increases significantly, indicating that the grafting has reached equilibrium. Therefore, the further preferred complexation reaction time is 6-9 minutes, with 9 minutes being optimal.

[0084] Comparative Example 1

[0085] The only difference between this comparative example and Example 1 is that sodium dodecyl diphenyl ether disulfonate is not added during the etching process in step 1, and the front side of the PET is irradiated with a 312nm ultraviolet lamp for 12 hours and the back side for 9 hours during the etching process. All other steps and conditions are the same. The microstructure of the PET film with columnar pore structure obtained after etching is shown in the figure below. Figure 3 As shown.

[0086] Depend on Figure 3 As can be seen in (a) and (b), the channels at both ends of the front and back sides are symmetrical and have similar sizes. The cross section in (c) further confirms its cylindrical pore morphology. The IV curve in (d) is symmetrical, which is consistent with the morphology and current characteristics of a cylindrical pore. It does not have an ion rectification effect, thus effectively distinguishing between symmetrical and asymmetrical pore types. Its current amplification effect is not as good as that of the single bullet-shaped nanopore in Example 1.

Claims

1. A 4-APM / Zr-MOF / PET nanopore sensor based on spatial modification, characterized in that: The invention comprises a PET film, a Zr-MOF, and a probe 4-APM; the PET film is etched with a bullet-shaped nanoporous structure; the Zr-MOF is complexed into the bullet-shaped nanoporous structure of the PET film, and the probe 4-APM is coupled onto the Zr-MOF; wherein, 4-APM is 4-aminophenyl-α-D-mannopyranoside. The nanopore sensor is prepared by the following steps: After S1 PET film is bombarded with heavy ions to form tracks and activated, it is placed in an alkaline solution containing surfactant for asymmetric etching to obtain a PET film with bullet-shaped nanopore structure. S2 The PET membrane with bullet-shaped nanopore structure is mixed with zirconium salt, amino-containing organic ligand, organic solvent and morphology modifier and then subjected to in-situ growth reaction to obtain Zr-MOF / PET composite material; S3 The Zr-MOF / PET composite material, after being activated with glutaraldehyde, is impregnated in a 4-APM solution and undergoes a coupling reaction; The nanopore sensor is used for the detection of concanavalin A.

2. A method for fabricating a 4-APM / Zr-MOF / PET nanopore sensor based on spatial modification as described in claim 1, characterized in that: Includes the following steps: After S1 PET film is bombarded with heavy ions to form tracks and activated, it is placed in an alkaline solution containing surfactant for asymmetric etching to obtain a PET film with bullet-shaped nanopore structure. S2 The PET membrane with bullet-shaped nanopore structure is mixed with zirconium salt, amino-containing organic ligand, organic solvent and morphology modifier and then subjected to in-situ growth reaction to obtain Zr-MOF / PET composite material; S3 The Zr-MOF / PET composite material is activated with glutaraldehyde and then impregnated in 4-APM solution, followed by a coupling reaction to obtain the final product.

3. The method for fabricating a 4-APM / Zr-MOF / PET nanopore sensor based on spatial modification according to claim 2, characterized in that: In S1, The activation treatment involves irradiating one side of the PET film with ultraviolet light for 10-12 hours; The surfactants in the alkaline solution containing surfactants include anionic surfactants; The concentration of the alkaline solution containing the surfactant is 5-6 mol / L; The temperature for the asymmetric etching is 50~60℃.

4. The method for fabricating a 4-APM / Zr-MOF / PET nanopore sensor based on spatial modification according to claim 3, characterized in that: The mass fraction of the surfactant in the alkaline solution containing surfactant is 0.05~0.1%.

5. The method for fabricating a 4-APM / Zr-MOF / PET nanopore sensor based on spatial modification according to claim 2, characterized in that: In S2, The zirconium salt is at least one of zirconium chloride and zirconium oxychloride octahydrate; The amino-containing organic ligands include 2-amino-4,4'-biphenyl dicarboxylic acid; The organic solvent is at least one of DMF, N,N-diethylformamide and tetrahydrofuran; The morphology modifier is at least one of formic acid and acetic acid.

6. The method for fabricating a 4-APM / Zr-MOF / PET nanopore sensor based on spatial modification according to claim 5, characterized in that: In S2, the temperature of the in-situ growth reaction is 100~120℃ and the time is 12~24h.

7. The method for fabricating a 4-APM / Zr-MOF / PET nanopore sensor based on spatial modification according to claim 6, characterized in that: In the in-situ growth reaction, the mass ratio of zirconium salt, amino-containing organic ligand, organic solvent, and speciation modifier is (0.48~0.5): (0.26~0.28): (28~31): (3.5~3.8).

8. The method for fabricating a 4-APM / Zr-MOF / PET nanopore sensor based on spatial modification according to claim 2, characterized in that: In S3 The activation conditions for glutaraldehyde are: a concentration of glutaraldehyde of 2-3 wt%, a temperature of 4-10 °C, and a time of 6-10 h; the concentration of the 4-APM solution is 0.1-0.5 μg / mL. The coupling reaction takes 20-24 hours.

9. An application of the 4-APM / Zr-MOF / PET nanopore sensor based on spatial modification as described in claim 1, characterized in that: It is used for the detection of concanavalin A.

10. The application of the 4-APM / Zr-MOF / PET nanopore sensor based on spatial modification according to claim 9, characterized in that: The specific detection process is as follows: an electrochemical detection method is performed using a 4-APM / Zr-MOF / PET nanopore sensor with conductivity detection. A linear fitting curve is established between the conductivity of the sensor after reacting with concanavalin A and the concentration of concanavalin A. The concentration of concanavalin A in the test solution is then calculated using the linear fitting curve.

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