Sensing detection application and sensor for identifying 6PPD and 6PPD-Q based on cyclodextrin subject and object

Abstract

The invention discloses a sensing detection application and a sensor for identifying 6PPD and 6PPD-Q based on a cyclodextrin subject and object, and relates to the technical field of pollutant detection. Specifically, the invention provides an application of at least one of cyclodextrin, functional group modified cyclodextrin and polycyclodextrin in detection of 6PPD or 6PPD-Q. According to the invention, cyclodextrin, functional group modified cyclodextrin and polycyclodextrin can selectively recognize and combine with 6PPD and 6PPD-Q hydrophobic molecules through a subject-object inclusion effect. Cyclodextrin, functional group modified cyclodextrin and polycyclodextrin can be used as ideal molecular recognition elements of 6PPD and 6PPD-Q, have high selectivity and specificity, are convenient and fast to operate, can realize linear response to 6PPD in a concentration range of 0.01-30 [mu] M, and have a detection limit as low as 4.13 nM.

Description

Technical Field

[0001] This invention relates to the field of pollutant detection technology, and in particular to a sensing application and sensor based on the cyclodextrin subject-guest recognition of 6PPD and 6PPD-Q. Background Technology

[0002] "Urban runoff mortality syndrome," the acute death of coho salmon following heavy rain runoff, has been identified as primarily caused by N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine-quinone (6PPD-Q). 6PPD-Q is a product of the ozone oxidation of N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD), an antioxidant widely used in tires. Experiments have shown that coho salmon are extremely sensitive to 6PPD-Q, with a 96-hour median lethal concentration (LC50) of [a certain value]. 50 The concentration of 6PPD-Q is only 41-95 ng / L, far lower than most environmental detection concentrations. This finding reveals the potentially serious ecological risks of tire-derived pollutants in urban runoff, posing new challenges to the protection of aquatic ecosystem health. As a precursor to 6PPD-Q, 6PPD is widely used in rubber products, including automobile tires, rubber asphalt, and protective cushioning materials. Due to its large usage and continuous environmental release, 6PPD and its oxidation product 6PPD-Q have been frequently detected in surface water, stormwater runoff, and even human biological samples. These findings indicate that both pose significant environmental exposure risks and have raised widespread ecological and health safety concerns. Given their potential hazards, the U.S. Environmental Protection Agency (EPA) has set a screening limit of 8.9 µg / L (33 nM) for aquatic organisms of 6PPD and 11 ng / L for 6PPD-Q. -1 (37 pM).

[0003] Currently, the detection of 6PPD and 6PPD-Q mainly relies on high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS / MS). Although this method offers high sensitivity and accuracy, its complex pretreatment, cumbersome analytical procedures, and expensive instruments limit its application in routine monitoring and rapid on-site detection. Sensor detection, due to its low cost, rapid response, and ease of operation, has received widespread attention in the field of pollutant monitoring in recent years. Given the inherent electrochemical activity of 6PPD, researchers have attempted to construct various electrochemical sensing platforms to achieve its sensitive detection. For example, some studies have significantly enhanced the catalytic activity of carbon paste electrodes by modifying the surface with zinc oxide or γ-Mo2N composite materials, thus achieving highly sensitive detection of 6PPD; other studies have used flexible screen-printed carbon electrodes loaded with Fe2O3 / carbon nanotube electrocatalysts to achieve real-time, non-destructive monitoring of 6PPD in plants. However, despite the high sensitivity of these electrochemical sensors, their detection results are still susceptible to interference from coexisting electroactive substances, potentially leading to false or false positive signals, thus limiting their reliable application in complex environmental samples. Furthermore, literature reports that 6PPD can be oxidized in potassium persulfate (K₂S₂O₈) to form a red protonated product, N-1,3-dimethylbutyl-N′-phenylquinone diamine (6QDI). Based on this phenomenon, researchers have developed a rapid colorimetric detection kit for simple visual detection of 6PPD. While this method can distinguish 6PPD from monoaromatic or triaromatic compounds to some extent, it lacks sufficient selectivity for structurally similar diaromatic compounds, making it difficult to apply for accurate quantification in complex matrices. Moreover, there are currently no publicly reported sensor detection methods for 6PPD-Q.

[0004] Therefore, developing a recognition element that can specifically identify and sensitively detect 6PPD and its transformation product 6PPD-Q, and that is easy and quick to operate, is of great scientific significance and application value for improving the monitoring capabilities of this type of pollutant in the environment and for carrying out research on its migration, transformation and ecological risk assessment. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a sensing and detection application and sensor based on the host-guest recognition of 6PPD and 6PPD-Q by cyclodextrin, and to provide a recognition material and sensor that can specifically identify and sensitively detect 6PPD and its conversion product 6PPD-Q, and is convenient and quick to operate.

[0006] The technical solution of the present invention is as follows: In a first aspect, the present invention provides the use of at least one of cyclodextrin, functionally modified cyclodextrin, and polycyclodextrin in the detection of 6PPD or 6PPD-Q, wherein 6PPD is N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine, and 6PPD-Q is N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine-quinone.

[0007] Optionally, the functional groups include -NH2, -COOH, -SH, -OH, and -SO3. - At least one of -CH3.

[0008] Optionally, the polycyclodextrin is prepared by polymerization, wherein the polymerization method is selected from one of chemical polymerization, template-directed polymerization, thermally induced polymerization, interfacial polymerization, sol-gel polymerization, and self-assembly polymerization.

[0009] In a second aspect, the present invention provides a fluorescence sensor, wherein the fluorescence sensor includes a recognition element, the recognition element including a recognition material and / or a fluorescently responsive material modified with the recognition material, the recognition material including at least one of cyclodextrin, functionally modified cyclodextrin, and polycyclodextrin.

[0010] A third aspect of the present invention provides a photoelectrochemical sensor, wherein the photoelectrochemical sensor includes a working electrode, a counter electrode, and a reference electrode, the working electrode comprising a photoactive material modified with a recognition material, the recognition material comprising at least one selected from cyclodextrin, functionally modified cyclodextrin, and polycyclodextrin; or, The photoelectrochemical sensor includes a working electrode, a counter electrode, and a reference electrode. The working electrode includes a photoactive layer and a recognition layer modified on the surface of the photoactive layer. The recognition layer includes a recognition material, which includes at least one of cyclodextrin, functionally modified cyclodextrin, and polycyclodextrin. The photoactive layer includes a photoactive material.

[0011] A fourth aspect of the present invention provides an electrochemical sensor, wherein the electrochemical sensor includes a working electrode, a counter electrode, and a reference electrode, the working electrode comprising an electrocatalytically active material modified with a recognition material, the recognition material comprising at least one selected from cyclodextrin, functionally modified cyclodextrin, and polycyclodextrin; or, The electrochemical sensor includes a working electrode, a counter electrode, and a reference electrode. The working electrode includes an electrocatalytic layer and a recognition layer modified on the surface of the electrocatalytic layer. The recognition layer includes a recognition material, which includes at least one of cyclodextrin, functionally modified cyclodextrin, and polycyclodextrin. The electrocatalytic layer includes an electrocatalytically active material.

[0012] Optionally, the electrocatalytic active material includes at least one of graphene, carbon nanotubes, and MOF materials.

[0013] A fifth aspect of the present invention provides an electrochemiluminescence sensor, wherein the electrochemiluminescence sensor includes a working electrode, a counter electrode, and a reference electrode, the working electrode comprising an electrochemiluminescence material modified with a recognition material, the recognition material comprising at least one selected from cyclodextrin, functionally modified cyclodextrin, and polycyclodextrin; or, The electrochemiluminescence sensor includes a working electrode, a counter electrode, and a reference electrode. The working electrode includes an electrochemiluminescence layer and a recognition layer modified on the surface of the electrochemiluminescence layer. The recognition layer includes a recognition material, which includes at least one of cyclodextrin, functionally modified cyclodextrin, and polycyclodextrin. The electrochemiluminescence layer includes an electrochemiluminescence material.

[0014] Optionally, the electrochemiluminescent material includes at least one of metal complexes, quantum dots, organic small molecule luminescent materials, and polymer luminescent materials.

[0015] In a sixth aspect, the present invention provides a colorimetric sensor, wherein the colorimetric sensor comprises a colorimetric reaction material, a recognition material, and a carrier support material, wherein the recognition material comprises at least one selected from cyclodextrin, functionally modified cyclodextrin, and polycyclodextrin.

[0016] Beneficial Effects: In this invention, cyclodextrins, functionally modified cyclodextrins, and polycyclodextrins can selectively recognize and bind to 6PPD and 6PPD-Q hydrophobic molecules through host-guest inclusion interactions. Cyclodextrins, functionally modified cyclodextrins, and polycyclodextrins can serve as ideal molecular recognition elements for 6PPD and 6PPD-Q, exhibiting high selectivity and specificity, and are convenient and quick to operate. They achieve a linear response to 6PPD within a concentration range of 0.01–30 μM, with a detection limit (LOD) as low as 4.13 nM. Therefore, different types of sensors can be constructed based on cyclodextrins, functionally modified cyclodextrins, and polycyclodextrins for the detection of 6PPD and 6PPD-Q. Attached Figure Description

[0017] Figure 1 This is a schematic diagram illustrating the recognition mechanism of cyclodextrin for 6PPD and 6PPD-Q.

[0018] Figure 2 The figure shows the ITC characterization results of β-cyclodextrin for host-guest recognition of 6PPD in Example 1. In the figure, a is the ITC characterization result of β-cyclodextrin (20 mM) and 6PPD (1 mM); b is the ITC characterization result of β-cyclodextrin (20 mM) and pure solvent (phosphate buffer).

[0019] Figure 3The figure shows the ITC characterization results of β-cyclodextrin for host-guest recognition of 6PPD-Q in Example 2. In the figure, a is the ITC characterization result of β-cyclodextrin (10 mM) and 6PPD-Q (200 µM); b is the ITC characterization result of β-cyclodextrin (10 mM) and pure solvent (phosphate buffer).

[0020] Figure 4 The figure shows the results of the molecular docking simulation analysis of β-cyclodextrin and 6PPD in Example 3, where a is a side view and b is a top view.

[0021] Figure 5 The figure shows the results of the molecular docking simulation analysis of β-cyclodextrin and 6PPD-Q in Example 4, where a is a side view and b is a top view.

[0022] Figure 6 The image shows the NMR results of β-cyclodextrin, 6PPD and the β-cyclodextrin-6PPD inclusion complex in Example 5, as well as the structural formulas of β-cyclodextrin and 6PPD.

[0023] Figure 7 The following are fluorescence emission spectra of different substances in Example 6, where a is the fluorescence emission spectrum of β-cyclodextrin, 6PPD and β-cyclodextrin-6PPD inclusion complex, and b is the fluorescence emission spectrum of β-cyclodextrin, 6PPD-Q and β-cyclodextrin-6PPD-Q inclusion complex.

[0024] Figure 8 This is a schematic diagram of a fluorescence sensor that uses β-cyclodextrin as the recognition material for 6PPD detection.

[0025] Figure 9 The image shows the fluorescence detection results of β-cyclodextrin identifying different concentrations of 6PPD in Example 7, where a is the fluorescence emission spectrum and b is the linear fitting result.

[0026] Figure 10 The diagram shows the structural formula of the interfering object in Example 8, as well as the results of the selective test and the anti-interference test. In this diagram, a is the structural formula of the interfering object, and b is the result of the selective test and the anti-interference test.

[0027] Figure 11 This is a schematic diagram of a photoelectrochemical sensor for detecting 6PPD, constructed using β-cyclodextrin as the recognition material.

[0028] Figure 12 The graph shows the photoelectrochemical detection results of the photoelectrochemical sensor in Example 11, which identifies different concentrations of 6PPD. In the graph, a is the photocurrent intensity graph and b is the linear fitting result graph.

[0029] Figure 13 The graph shows the results of the selectivity and anti-interference test of the photoelectrochemical sensor in Example 12. Detailed Implementation

[0030] This invention provides a sensing and detection application and sensor based on cyclodextrin subject-guest recognition 6PPD and 6PPD-Q. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0031] Unless otherwise defined, all technical and scientific terms used herein 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 be limiting of the invention.

[0032] If the embodiments of the present invention involve descriptions such as "first" or "second", such descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated.

[0033] This invention provides the application of at least one of cyclodextrin, functionalized cyclodextrin, and polycyclodextrin in the detection of 6PPD or 6PPD-Q.

[0034] In this invention, cyclodextrins, functionally modified cyclodextrins, and polycyclodextrins can selectively recognize and bind to 6PPD and 6PPD-Q hydrophobic molecules through host-guest inclusion interactions. Cyclodextrins, functionally modified cyclodextrins, and polycyclodextrins can serve as ideal molecular recognition elements for 6PPD and 6PPD-Q, exhibiting high selectivity and specificity, and are convenient and quick to operate. They achieve a linear response to 6PPD within a concentration range of 0.01–30 μM, with a detection limit (LOD) as low as 4.13 nM.

[0035] In this invention, cyclodextrin specifically refers to β-cyclodextrin (βCD), a typical cyclic oligosaccharide composed of carbon, oxygen, and hydrogen elements. Its molecules have a bowl-shaped structure with a hydrophobic inner cavity and a hydrophilic outer surface. The cavity diameter of β-cyclodextrin is approximately 6.0–7.0 Å, while 6PPD and 6PPD-Q are hydrophobic molecules composed of carbon, nitrogen, and oxygen, with a molecular width of approximately 6.5 Å. Figure 1As shown, this high degree of spatial matching enables β-cyclodextrin to selectively recognize and bind to 6PPD and 6PPD-Q hydrophobic molecules through host-guest inclusion interactions (6PPD and 6PPD-Q can bind to the internal hydroxyl groups of β-cyclodextrin through hydrogen bonding, forming stable hydrogen-bonded inclusion complexes based on suitable spatial matching). Based on this characteristic, β-cyclodextrin can serve as an ideal molecular recognition element for 6PPD and 6PPD-Q, exhibiting high selectivity and specificity, achieving a linear response to 6PPD within the concentration range of 0.01–30 μM, with a detection limit (LOD) as low as 4.13 nM.

[0036] In some embodiments, the functional groups include -NH2, -COOH, -SH, -OH, and -SO3. - At least one of -CH3 and -CH3. These functional groups can enhance the interaction between cyclodextrin and functional materials, thereby improving the performance of the sensor and achieving more sensitive detection.

[0037] Optionally, the polycyclodextrin is prepared by polymerization, wherein the polymerization method is selected from, but not limited to, one of chemical polymerization (e.g., pure chemical polymerization, electrochemical polymerization or photochemical polymerization), template-directed polymerization, thermally induced polymerization, interfacial polymerization, sol-gel polymerization and self-assembly polymerization.

[0038] This invention also provides a fluorescence sensor, wherein the fluorescence sensor includes a recognition element, and the recognition element includes a recognition material.

[0039] This invention also provides another fluorescence sensor, wherein the fluorescence sensor includes a recognition element, and the recognition element includes a fluorescence-responsive material modified with a recognition material.

[0040] The present invention also provides another fluorescence sensor, wherein the fluorescence sensor includes a recognition element, the recognition element including a recognition material and a fluorescence-responsive material modified with the recognition material.

[0041] In the aforementioned fluorescence sensor, the recognition material includes at least one of cyclodextrin, functionally modified cyclodextrin, and polycyclodextrin.

[0042] In some embodiments, the fluorescent responsive material includes inorganic quantum dots (such as CdSe, UIO-66 QDs, etc.) and rare earth-doped luminescent materials (such as NaYF4:Eu). 3+ 、Tb 3+These fluorescent materials include carbon-based fluorescent materials (such as carbon dots and graphene quantum dots), organic fluorescent dyes (such as rhodamine, fluorescein, and coumarin), and conjugated polymer fluorescent materials. These fluorescent response materials possess tunable emission wavelengths, high quantum efficiency, and excellent photostability, and are widely used in fluorescence sensing. By modifying recognition materials onto fluorescent response materials, fluorescence sensing detection of guest molecules at different concentrations (6PPD or 6PPD-Q) can be achieved.

[0043] This invention also provides a photoelectrochemical sensor, wherein the photoelectrochemical sensor includes a working electrode, a counter electrode, and a reference electrode, the working electrode includes a photoactive material modified with a recognition material, and the recognition material includes at least one of cyclodextrin, functionally modified cyclodextrin, and polycyclodextrin.

[0044] In some embodiments, the method for preparing the working electrode includes the following steps: 10-1000 mg of the photoactive material modified with the recognition material was added to a mixed solution of 10-500 µL of ethanol and 1-20 µL of Nafion (perfluorosulfonic acid-polytetrafluoroethylene copolymer), and sonicated for 10 min-2 h to disperse it evenly to obtain a dispersion. Then, take 5~100 µL of the dispersion and drop it onto the substrate electrode (such as ITO electrode, glassy carbon electrode, screen-printed electrode, Au electrode, etc.), and let it air dry naturally to obtain the working electrode.

[0045] In some embodiments, the working electrode can also be prepared by the following method: Electropolymerization: Monomers (such as pyrrole, aniline, EDOT, etc.) are polymerized in situ on the surface of the substrate electrode by potential scanning or constant potential, and photoactive materials modified by recognition materials are co-embedded or covalently grafted into the conductive polymer film, which has both strong adhesion and conductivity.

[0046] Sol-gel immobilization: Using silane or organometallic precursors as a matrix, photoactive materials modified with recognition materials are embedded in an inorganic-organic hybrid network on the surface of the substrate electrode through a hydrolysis-condensation reaction, exhibiting excellent chemical stability and controllable pore structure.

[0047] Template-directed assembly: Using the target molecule or its analogue as a template, and with the help of molecular imprinting or host-guest templated reactions, a functional recognition membrane with specific binding sites can be constructed to achieve highly selective detection.

[0048] Surface coating or encapsulation: Photoactive materials modified with recognition materials are blended with nanoparticles, quantum dots, or metal oxides and then embedded into the composite material through coating, co-precipitation, or in-situ growth to form on the surface of the substrate electrode, thus balancing stability and signal transmission efficiency.

[0049] In some implementations, an Ag / AgCl electrode or a saturated calomel electrode is used as the reference electrode, and a platinum wire or platinum sheet is used as the counter electrode.

[0050] Alternatively, another photoactive material with opposite photocurrent polarity can be selected as the reference electrode and counter electrode. For example, if the photoactive material of the working electrode is a cathode photocurrent, then a photoactive material with an anode photocurrent can be selected as the reference electrode and counter electrode, thus forming a self-powered photoelectrochemical sensor. The advantage of a self-powered photoelectrochemical sensor is that light energy directly drives the electrochemical reaction, achieving signal output without the need for an external bias voltage. This system not only has the advantages of low energy consumption, low noise, and high sensitivity, but also excellent portability and environmental friendliness, enabling stable and sensitive target detection in complex environments. In some embodiments, the recognition material can be modified or fixed onto the surface of the photoactive material through various methods, specifically including the following methods: Physical adsorption: Recognition materials can spontaneously adsorb onto the surface of photoactive materials through van der Waals forces, electrostatics, or hydrophobic interactions. This method is simple to operate and maintains activity, but its stability is relatively weak. For example, mixing photoactive materials with cyclodextrin in ethanol or deionized water and sonicating for 30 min to 3 h, followed by drying, can physically adsorb the photoactive materials and cyclodextrin together through electrostatics or van der Waals forces.

[0051] Covalent coupling: Using activating groups (such as carboxyl-amino, mercapto-gold, epoxy-hydroxyl reactions, etc.) to form stable chemical bonds between recognition materials and photoactive materials is one of the most commonly used immobilization methods.

[0052] For example, the modification of common Au-SH covalent bonds includes the following steps: First, gold nanoparticles are modified onto photoactive materials to obtain gold nanoparticle-modified photoactive materials. The modification methods mainly include the following three: (1) Directly drop-coat 0.01~0.2 mg / mL gold nanoparticles onto the surface of a photoactive material to obtain a photoactive material modified with gold nanoparticles (specifically, a suspension of the photoactive material can be drop-coatled onto a substrate and allowed to air dry to form a photoactive material layer; a solution of gold nanoparticles can be drop-coatled onto the surface of the photoactive material layer on the substrate and allowed to air dry to obtain a photoactive material layer modified with gold nanoparticles). (2) After mixing the photoactive material (10~500 mg) with chloroauric acid solution (0.1~5 mM), place it under a xenon lamp for 30 min~5 h to allow the gold nanoparticles to be photodeposited on the surface of the photoactive material, and obtain the gold nanoparticle-modified photoactive material (this method can also be used to modify the surface of the photoactive material layer located on the substrate). (3) Immerse the photoactive material in a solution containing chloroauric acid (0.1~5 mM) and electrodeposit at a constant potential (0.1~0.5 V) for 10 min~2 h to allow gold nanoparticles to be electrodeposited onto the surface of the photoactive material, thereby obtaining a gold nanoparticle-modified photoactive material (specifically, the substrate containing the photoactive material layer on the surface can be immersed in a solution containing chloroauric acid for electrodeposition).

[0053] Then, the substrate containing a photoactive material layer modified with gold nanoparticles is immersed in a solution containing a recognition material modified with thiol groups, and left to stand for 12-16 h. Based on the Au-SH covalent interaction, the recognition material is then modified onto the surface of the photoactive material layer; or... The photoactive material modified with gold nanoparticles (concentration of 20~100 µg / mL) was mixed with the recognition material modified with thiol groups (-SH- recognition material, concentration of 0.1~20 mM) for 12~16 h, and the recognition material was modified onto the surface of the photoactive material based on the Au-SH covalent interaction.

[0054] Another common EDC-NHS covalent modification method includes the following steps: First, the photoactive material is mixed with 0.5-10 mM mercaptoacetic acid and stirred for 5-12 h to modify the carboxyl group onto the photoactive material, thus obtaining a carboxyl-modified photoactive material. Then, the carboxyl-modified photoactive material was dispersed in a mixture of 0.1-1 M EDC (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride) and 0.1-0.5 M NHS (N-hydroxysuccinimide) and immersed for 30 min to 2 h to activate the carboxyl groups on the surface of the photoactive material.

[0055] Subsequently, the photoactive material with activated surface carboxyl groups and the amino-modified recognition material were incubated overnight (12-16 h) to modify the recognition material onto the surface of the photoactive material (the recognition material can also be modified onto the surface of the photoactive material layer on the substrate by the above method).

[0056] This invention also provides another photoelectrochemical sensor, wherein the photoelectrochemical sensor includes a working electrode, a counter electrode, and a reference electrode (forming a three-electrode system required for the photoelectrochemical sensor). The working electrode includes a photoactive layer and a recognition layer modified on the surface of the photoactive layer (the recognition layer can be a dense layer or a sparse layer; when it is a sparse layer, the underlying photoactive layer can be exposed in the recognition layer). The recognition layer includes a recognition material, which includes at least one of cyclodextrin, functionally modified cyclodextrin, and polycyclodextrin. The photoactive layer includes a photoactive material.

[0057] In some embodiments, the photoactive material includes a heterojunction photoactive material, which includes at least one of type II heterojunction photoactive materials, Z-type heterojunction photoactive materials, S-type heterojunction photoactive materials, ternary type II heterojunction photoactive materials, ternary Z-type heterojunction photoactive materials, and ternary S-type heterojunction photoactive materials, but is not limited thereto.

[0058] This invention also provides an electrochemical sensor, wherein the electrochemical sensor includes a working electrode, a counter electrode, and a reference electrode, the working electrode includes an electrocatalytically active material modified with a recognition material, the recognition material including at least one of cyclodextrin, functionally modified cyclodextrin, and polycyclodextrin.

[0059] The preparation methods for the working electrode and the photoactive material modified with the electrocatalytic active material in the above-mentioned photoelectrochemical sensor can be found in the preparation methods of the working electrode and the photoactive material modified with the photoactive material.

[0060] This invention also provides another electrochemical sensor, wherein the electrochemical sensor includes a working electrode, a counter electrode, and a reference electrode. The working electrode includes an electrocatalytic layer and a recognition layer modified on the surface of the electrocatalytic layer (the recognition layer can be a dense layer or a sparse layer; when it is a sparse layer, the underlying photoactive layer can be exposed in the recognition layer). The recognition layer includes a recognition material, which includes at least one of cyclodextrin, functionally modified cyclodextrin, and polycyclodextrin. The electrocatalytic layer includes an electrocatalytically active material.

[0061] In some embodiments, the electrocatalytic active material includes at least one of graphene, carbon nanotubes, and MOF materials, but is not limited thereto.

[0062] This invention also provides an electrochemiluminescence sensor, wherein the electrochemiluminescence sensor includes a working electrode, a counter electrode, and a reference electrode. The working electrode includes an electrochemiluminescence material modified with a recognition material, wherein the recognition material includes at least one selected from cyclodextrin, functionally modified cyclodextrin, and polycyclodextrin. The working electrode and the electrochemiluminescence material modified with the recognition material can be prepared using the methods described above for preparing the working electrode and the photoactive material modified with the recognition material in the photoelectrochemical sensor.

[0063] This invention also provides another electrochemiluminescence sensor, wherein the electrochemiluminescence sensor includes a working electrode, a counter electrode, and a reference electrode. The working electrode includes an electrochemiluminescence layer and a recognition layer modified on the surface of the electrochemiluminescence layer (the recognition layer can be a dense layer or a sparse layer; when it is a sparse layer, the underlying photoactive layer can be exposed in the recognition layer). The recognition layer includes a recognition material, which includes at least one of cyclodextrin, functionally modified cyclodextrin, and polycyclodextrin. The electrochemiluminescence layer includes an electrochemiluminescence material.

[0064] In some embodiments, the electrochemiluminescent material includes a metal complex (such as Ru(bpy)3). 2+ At least one of the following: Ir(ppy)3), quantum dots (CdSe quantum dots, g-C3N4 quantum dots, carbon quantum dots, graphene quantum dots), organic small molecule light emitters, and polymer light emitters (such as luminol, carbazole polymers, etc.).

[0065] This invention also provides a colorimetric sensor, wherein the colorimetric sensor includes a colorimetric reaction material, a recognition material, and a carrier support material, and the recognition material includes at least one of cyclodextrin, functionally modified cyclodextrin, and polycyclodextrin.

[0066] In some embodiments, the colorimetric material includes metal nanoparticles with surface plasmon resonance properties (such as Au nanoparticles and Ag nanoparticles), enzyme-like nanozyme catalysts (such as Fe3O4, MnO2, MOFs, etc.), or organic colorimetric dyes and metal complex systems, which can produce obvious color changes through redox, coordination, or aggregation-depolymerization reactions. Recognition materials such as cyclodextrins, functionally modified cyclodextrins, and polycyclodextrins impart high selectivity to the system. The support material can specifically be paper-based, polymer film, or inorganic nanocomposite substrate, which can provide a stable fixed interface and signal amplification platform for the colorimetric reaction.

[0067] The present invention will be further described below through specific embodiments.

[0068] Example 1: Isothermal titration calorimetry (ITC) characterization of β-cyclodextrin (βCD) for host-guest recognition of 6PPD At 25 °C, 20 mM βCD solution (phosphate buffer, pH 7.4) was titrated stepwise into a sample cell containing 1 mM 6PPD solution (phosphate buffer, pH 7.4). The heat change was recorded in real time. The obtained thermotiter curve was integrated and then fitted to obtain thermodynamic parameters such as dissociation constant (kd), enthalpy change (ΔH), and entropy change (ΔS) to evaluate the thermodynamic properties of the combination of the two.

[0069] Simultaneously, 20 mM βCD solution (solvent is phosphate buffer, pH 7.4) was gradually titrated into a sample cell containing pure solvent (pure solvent is phosphate buffer, pH 7.4) for TIC testing as a control.

[0070] The results are as follows Figure 2 As shown, the results indicate that βCD exhibits a significant exothermic reaction upon binding with 6PPD. Fitting the titration curves based on a single binding site model yielded a dissociation constant (Kd) of 2.11 μM and an enthalpy change (ΔH) of -127.1 kcal·mol⁻¹ for βCD and 6PPD. -1 The entropy change (ΔS) is 25.5 cal·mol⁻¹ -1 ·K -1 The dissociation constant (Kd) of 2.11 μM indicates a strong host-guest interaction between βCD and 6PPD. This binding strength is sufficient to form a stable inclusion complex in aqueous solution, and it is not irreversible, consistent with typical non-covalent host-guest recognition characteristics. The negative ΔH indicates that the binding process is exothermic, reflecting a favorable host-guest interaction. The positive ΔS indicates an entropy-driven effect in the binding process, possibly stemming from the release of structured water molecules after the hydrophobic guest molecule 6PPD enters the βCD cavity. The free energy change (ΔG) calculated according to the Gibbs–Helmholtz equation is... 89.2 kcal·mol - ¹ indicates that the inclusion process is thermodynamically spontaneous.

[0071] The βCD titration experiment using pure solvent as a control showed almost no thermal effect, ruling out the influence of the heat of dilution. In summary, the ITC results indicate that βCD and 6PPD can form stable and spontaneous inclusion complexes, and their binding process is driven by both enthalpy and entropy effects.

[0072] Example 2: ITC characterization of βCD for 6PPD-Q subject-object recognition At 25 °C, 10 mM βCD solution (phosphate buffer, pH 7.4) was titrated stepwise into a sample cell containing 200 µM 6PPD-Q solution (phosphate buffer, pH 7.4). The heat change was recorded in real time. The obtained thermotiter curve was integrated and then fitted to obtain thermodynamic parameters such as dissociation constant (kd), enthalpy change (ΔH), and entropy change (ΔS) to evaluate the thermodynamic properties of the combination of the two.

[0073] Note: The concentration of the 6PPD-Q solution used is lower than that of the 6PPD solution in Example 1 because the ITC test was performed in phosphate buffer, and 6PPD-Q is less water-soluble than 6PPD. Therefore, the concentration of the 6PPD-Q solution used was 200 µM instead of 1 mM.

[0074] Simultaneously, 10 mM βCD solution was gradually titrated into a sample cell containing pure solvent (phosphate buffer, pH 7.4) for TIC testing as a control.

[0075] The results are as follows Figure 3 As shown, the results indicate that βCD and 6PPD-Q exhibit a significant exothermic reaction. Fitting the titration curves based on a single binding site model yielded a dissociation constant (Kd) of 2.01 μM and an enthalpy change (ΔH) of -51.09 kcal·mol⁻¹ for βCD and 6PPD-Q. -1 The entropy change (ΔS) is 25.9 cal·mol⁻¹. -1 ·K -1 The dissociation constant of βCDCD and 6PPD-Q is 2.01 μM, indicating a strong host-guest interaction and high binding affinity, enabling the formation of a stable inclusion complex. Similar to the result for 6PPD, this suggests that βCD can effectively recognize not only the parent molecule 6PPD but also its oxidation product 6PPD-Q, demonstrating good molecular recognition versatility. The negative ΔH indicates that the binding process is exothermic, reflecting a favorable host-guest interaction; while the positive ΔS indicates an entropy-driven effect, stemming from the release of structured water molecules after the hydrophobic guest molecule 6PPD-Q enters the βCD cavity. The free energy change (ΔG) calculated using the Gibbs–Helmholtz equation is -58.8 kcal·mol⁻¹. -1 This indicates that the inclusion process is thermodynamically spontaneous.

[0076] The βCD titration experiment using pure solvent as a control showed almost no thermal effect, ruling out the influence of the heat of dilution. In summary, the ITC results indicate that βCD and 6PPD-Q can form stable and spontaneous inclusion complexes, and their binding process is driven by both enthalpy and entropy effects.

[0077] Example 3: Molecular docking simulation analysis of βCD for host-guest recognition of 6PPD To explore the molecular recognition mechanism (binding configuration and interaction mechanism) between 6PPD and βCD, molecular docking simulation analysis was performed using AutoDock 4.2.6 software. Before docking, the system was pretreated by removing all water molecules and adding hydrogen atoms to both the ligand and acceptor molecules. A semi-flexible docking strategy was adopted, allowing the guest molecule's conformation to rotate freely while the host molecular skeleton remained rigid. The resulting binding conformations were sorted according to their binding free energy and visualized and analyzed using PyMOL software to assess the orientation of the host-guest inclusion complex and key intermolecular interactions.

[0078] The results are as follows Figure 4 As shown, the cavity size of βCD matches well with that of the 6PPD molecule, allowing 6PPD to be completely embedded within its cavity. In the resulting inclusion complex, 6PPD forms two N–H···O hydrogen bonds with the hydroxyl groups within the βCD cavity, with bond lengths of 2.109 Å and 2.105 Å, respectively, and a binding energy of -5.95 kcal·mol⁻¹. -1 The results demonstrate strong binding stability. These results indicate that 6PPD can selectively enter the cavity of βCD, stabilizing the host-guest inclusion complex through hydrogen bonding and spatial matching. This molecular docking result is highly consistent with the ITC test results in Example 1, further verifying the stable and specific inclusion relationship between βCD and 6PPD.

[0079] Example 4: Molecular docking simulation analysis of βCD for 6PPD-Q host-guest recognition In this embodiment, the steps for molecular docking simulation analysis are the same as in Example 3, and the results are as follows: Figure 5 As shown, the results indicate that the guest molecule 6PPD-Q can be completely embedded within the cavity of the βCD. According to theoretical calculations, 6PPD-Q forms two hydrogen bonds with the hydroxyl groups within the βCD cavity, with bond lengths of 2.040 Å and 1.909 Å, respectively, and a binding energy of -5.51 kcal·mol⁻¹. -1 The results show a strong interaction energy. This indicates that 6PPD-Q can bind to the internal hydroxyl groups of βCD via hydrogen bonding and form a stable hydrogen-bonded inclusion complex based on suitable spatial matching. This molecular docking result is highly consistent with the ITC test results in Example 2, further demonstrating the effective recognition and stable inclusion of 6PPD-Q by βCD.

[0080] Example 5: Nuclear magnetic resonance analysis of βCD for 6PPD subject-guest recognition To verify the formation and interaction characteristics of host-guest inclusion complexes and further evaluate the hydrogen chemical shift changes caused by the interaction between 6PPD and βCD, their ¹H NMR spectra were collected and analyzed. The chemical shift changes (Δδ) of individual guest molecules, individual host molecules, and corresponding inclusion complexes were compared to evaluate the type of interaction between host and guest molecules.

[0081] The results are as follows Figure 6 As shown, the results indicate that the characteristic alkyl proton (Ha) and aromatic proton (Hb) signals of 6PPD are clearly visible. In the spectrum of βCD, H1, H2, and H4 correspond to the protons located on the outer side, while H3, H5, and H6 correspond to the protons facing the inner cavity. In the βCD-6PPD inclusion complex (obtained by incubating a mixture of 10 mM βCD aqueous solution and 100 µM 6PPD aqueous solution for 30 min), all 6PPD proton signals show significant high-field shifts, and the inner cavity protons (H3, H5, and H6) of βCD also exhibit significant chemical shift changes, while the outer protons (H1, H2, and H4) are almost unaffected. These results suggest that 6PPD is successfully included in the cavity of βCD, and the -CH2- group of βCD may be affected by the shielding effect of the aromatic ring of 6PPD. These results indicate that the cavity size of βCD is highly matched with that of the 6PPD molecule, enabling complete inclusion, and the binding mechanism is highly consistent with the predictions of molecular docking simulations.

[0082] In summary, ¹H NMR results indicate that βCD provides the most stable host-guest recognition environment for 6PPD through its reasonable cavity size and significant internal hydrogen bonding interactions. Combined with results from ITC, molecular docking, and ¹H NMR, the findings further confirm that βCD is the recognition material for 6PPD. Its recognition mechanism is primarily driven by hydrophobic interactions, hydrogen bonding, and complementary spatial size effects, laying a solid theoretical foundation for the subsequent design and construction of sensors.

[0083] Example 6: Spectral characterization of βCD, 6PPD, and 6PPD-Q After mixing and incubating a 5 mM βCD aqueous solution with a 10 µM 6PPD aqueous solution for 30 min, a βCD-6PPD inclusion complex was obtained.

[0084] After mixing and incubating 5 mM βCD aqueous solution with 10 µM 6PPD-Q aqueous solution for 30 min, the βCD-6PPD-Q inclusion complex was obtained. Fluorescence emission spectra of βCD, 6PPD, and the βCD-6PPD inclusion complex were measured under 290 nm excitation; fluorescence emission spectra of βCD, 6PPD-Q, and the βCD-6PPD-Q inclusion complex were measured under 420 nm excitation. The results are as follows: Figure 7 As shown.

[0085] Depend on Figure 7 As shown in 'a', under 290 nm excitation, standalone βCD has no emission peak, while free 6PPD shows an emission peak at 399 nm. After free 6PPD binds to βCD to form an inclusion complex (corresponding to βCD+6PPD in the figure), the fluorescence intensity is significantly enhanced, indicating that the low polarity environment of the βCD cavity restricts the nonradiative relaxation pathway and stabilizes the excited state. These spectroscopic results confirm that βCD can provide the most suitable microenvironment for 6PPD inclusion. This conclusion is consistent with TIC testing, molecular docking, and NMR testing, and highlights the potential of βCD in fluorescence recognition applications.

[0086] Depend on Figure 7 As shown in b, under 420 nm excitation, standalone βCD emits no fluorescence, while free 6PPD-Q exhibits an emission peak at 630 nm. When 6PPD-Q forms an inclusion complex with βCD (corresponding to βCD+6PPD-Q in the figure), the fluorescence intensity significantly decreases. This is mainly because the 6PPD-Q molecule is confined within the cavity of βCD, restricting the intramolecular rotation or vibration between its benzene ring and quinone group, which may lead to an intramolecular fluorescence quenching effect. The above spectroscopic results confirm that βCD can provide the most suitable microenvironment for 6PPD-Q inclusion, a conclusion consistent with TIC testing, molecular docking, and NMR testing, highlighting the potential of βCD in fluorescence recognition applications.

[0087] It is evident that although βCD can recognize both 6PPD and 6PPD-Q, the spectral properties of 6PPD and 6PPD-Q after binding with βCD are completely different; the former shows enhanced fluorescence intensity, while the latter shows weakened fluorescence intensity.

[0088] Example 7 Fluorescence Detection of 6PPD Based on Subject-Object Recognition Technology The schematic diagram of fluorescence sensor detection of 6PPD based on subject-object recognition technology is as follows: Figure 8As shown, 6PPD alone exhibits a fluorescence emission spectrum at 399 nm under a fluorescence excitation wavelength of 290 nm, and the fluorescence emission spectrum intensity of the inclusion complex formed after 6PPD and βCD are fully incubated is significantly enhanced at 399 nm under a fluorescence excitation wavelength of 290 nm (as can also be seen from the fluorescence detection results of Example 6). Based on the fluorescence enhancement effect produced by 6PPD being included by βCD, an "on" type fluorescence sensor based on the host-guest interaction between βCD and 6PPD can be prepared. The specific verification process is as follows: First, a 15 mM βCD solution (using deionized water) was prepared. Then, different volumes of 6PPD stock solution were added to obtain mixtures with final 6PPD concentrations of 0.01 μM, 0.05 μM, 0.1 μM, 0.5 μM, 1 μM, 5 μM, 10 μM, and 30 μM. These mixtures were then placed in a shaker at 150 rpm for 30 min to allow sufficient host-guest interactions to form βCD-6PPD inclusion complexes. Finally, 1 mL of the completely reacted mixture was pipetted into a quartz fluorescent cuvette and placed in a fluorescence instrument for fluorescence emission spectroscopy (excitation wavelength 290 nm, spectral range 300–550 nm). The fluorescence emission intensity at different concentrations was recorded.

[0089] The results are as follows Figure 9 As shown, the fluorescence emission spectrum intensity increases with increasing 6PPD solution concentration, exhibiting a good linear relationship within the range of 0.01–30 μM. The fitted regression equation is y = 26509C + 2034 (R² = 0.9919, where C is the concentration). The calculated limit of detection (LOD = 3σ / S, where LOD represents the detection limit, σ represents the standard deviation of the blank sample, and S represents the slope of the calibration curve) is 4.13 nM, far below the freshwater screening threshold (33 nM) specified by the US Environmental Protection Agency (USEPA), indicating that the βCD-based sensor has high sensitivity and good practical application potential.

[0090] Example 8: Selectivity Test and Interference Immunity Test Structural analogs of the guest molecule (6PPD) were selected (including aniline, 1,2-dihydro-2,2,4-trimethylquinoline (TMQ), dopamine (DA), and ascorbic acid (AA)), as well as common matrix components (Na). + Cd 2+ Fe 2+ and Fe 3+ ( ) as an interfering substance.

[0091] Provides 15 µM βCD aqueous solution, 1 µM 6PPD aqueous solution, 1 µM aniline aqueous solution, 1 µM TMQ aqueous solution, 1 µM DA aqueous solution, 1 µM AA aqueous solution, 1 µM sodium chloride aqueous solution, 1 µM cadmium chloride aqueous solution, 1 µM ferrous chloride aqueous solution, and 1 µM ferric chloride aqueous solution.

[0092] The selectivity test was performed by incubating 1 mL of 6PPD aqueous solution and 1 mL of interfering substance aqueous solution with 1 mL of βCD aqueous solution for 30 min, respectively, and the fluorescence emission spectra were determined based on the fluorescence intensity to determine the selectivity of the host molecule to the guest molecule.

[0093] The results are as follows Figure 10 As shown, the results indicate that the fluorescence intensity after incubation of 6PPD with βCD is approximately 30 × 10⁻⁶. 3 Around, after aniline was incubated with βCD, after TMQ was incubated with βCD, after DA was incubated with βCD, after AA was incubated with βCD, Na + After incubation with βCD, Cd 2+ After incubation with βCD, Fe 2+ After incubation with βCD and Fe 3+ The fluorescence intensity after incubation with βCD is about 10% of the fluorescence intensity after incubation with 6PPD and βCD under the same conditions, which is almost negligible, indicating that the constructed fluorescence sensor has good selectivity.

[0094] The anti-interference performance test involves mixing the guest molecule (6PPD) and the interfering agent in a certain proportion, incubating them with βCD, and then performing fluorescence emission spectroscopy. The measured fluorescence emission intensity is then compared with the fluorescence emission intensity obtained after 6PPD is incubated with βCD to determine the anti-interference performance of βCD in detecting 6PPD.

[0095] The anti-interference performance test involved mixing 1 µM 6PPD, 1 µM aniline, 1 µM TMQ, 1 µM DA, 1 µM AA, 1 µM sodium chloride, 1 µM cadmium chloride, 1 µM ferrous chloride, and 1 µM ferric chloride with deionized water to obtain a mixed solution. 1 mL of this mixed solution was incubated with 1 mL of 15 mM βCD aqueous solution for 30 min, followed by fluorescence intensity testing. The results are as follows: Figure 10 As shown, the fluorescence intensity of the mixture after incubation with βCD (corresponding to the mixture in the figure) was almost the same as that of 6PPD after incubation with βCD under the same conditions, indicating that the constructed βCD has good anti-interference ability.

[0096] The above results fully demonstrate that βCD has excellent selectivity and anti-interference ability, showing its good applicability in the detection of trace 6PPD.

[0097] Example 9: Performance Evaluation of a Photoelectrochemical Sensor for Detecting 6PPD Based on Subject-Guest Recognition Technology Photoelectrochemical sensors consist of a working electrode, a counter electrode (i.e., a platinum wire), and a reference electrode (i.e., an Ag / AgCl electrode).

[0098] The method for preparing the working electrode includes the following steps: like Figure 11 As shown, a photoactive material solution (concentration of 70 µg / mL, solvent of ethanol, and the photoactive material specifically selected is C3N4 / Cu2O heterojunction material) was drop-coated onto an ITO conductive glass electrode. After natural drying, a photoactive material layer was formed, resulting in an ITO / nanomaterial electrode. A gold nanoparticle solution (concentration of 0.05 mg / mL, solvent of ethanol) was drop-coated onto the surface of a photoactive material layer (the gold nanoparticles were fixed on the surface of the photoactive material layer based on electrostatic interactions). After natural drying, a metal nanoparticle-modified photoactive material layer was formed, resulting in an ITO / nanomaterial / Au electrode. A thiol-modified βCD solution (15 mM concentration of thiol-modified βCD, deionized water as solvent) was drop-coated onto a metal nanoparticle-modified photoactive material layer. Based on Au-SH interaction, βCD was covalently modified onto an ITO / nanomaterial / Au electrode. After natural drying, the working electrode was obtained.

[0099] During testing, the working electrode was immersed in 0.01 μM, 0.05 μM, 0.1 μM, 0.5 μM, 1 μM, 5 μM, 10 μM and 50 μM 6PPD solutions (solvent is deionized water) for 1 hour. After incubation, the working electrode was gently rinsed with deionized water and dried with nitrogen gas to remove non-specific adsorption on the surface.

[0100] Subsequently, the dried working electrode was placed in 0.1M phosphate buffer (pH 7.4), with a platinum wire used as the counter electrode and an Ag / AgCl electrode used as the reference electrode. These three electrodes were then connected to an electrochemical workstation, and photocurrent measurements were recorded for different concentrations of 6PPD.

[0101] The results are as follows Figure 12 As shown, the photoelectrochemical sensor exhibits a good linear response to 6PPD in the range of 0.01–50 μM, and its regression equation is I (μA) = -3.02581 log C (μM) + 10.7534 (R 2= 0.9920), and the calculated limit of detection (LOD) is 3.19 nM, which is significantly lower than the freshwater screening limit of 33 nM set by the US EPA. This indicates that the photoelectrochemical sensor has extremely high sensitivity and can achieve accurate detection of trace amounts of 6PPD.

[0102] Example 10: Selectivity and Anti-interference Test of Photoelectrochemical Sensor To further evaluate the selectivity and anti-interference capability of the photoelectrochemical sensor prepared in Example 9.

[0103] Prepare 1 µM 6PPD aqueous solution, 1 µM aniline aqueous solution, 1 µM TMQ aqueous solution, 1 µM DA aqueous solution, 1 µM MAA aqueous solution, 1 µM sodium chloride aqueous solution, 1 µM cadmium chloride aqueous solution, 1 µM ferrous chloride aqueous solution and 1 µM ferric chloride aqueous solution.

[0104] A mixed solution was obtained by mixing 1 µM 6PPD, 1 µM aniline, 1 µM TMQ, 1 µM DA, 1 µM AA, 1 µM sodium chloride, 1 µM cadmium chloride, 1 µM ferrous chloride, and 1 µM ferric chloride with deionized water.

[0105] The photocurrent of the working electrode prepared in Example 9 in phosphate buffer is recorded as I0. The photocurrent of the working electrode in phosphate buffer after being incubated for 1 hour in 6PPD aqueous solution, aqueous solutions of different interfering substances, and mixed solutions is recorded as I. The selectivity and anti-interference ability of the photoelectrochemical sensor are evaluated based on the decrease in photocurrent, that is, ΔI=I0-I.

[0106] The results are as follows Figure 13 As shown, after the working electrode was incubated in a 1 μM 6PPD aqueous solution, the photocurrent decreased by 10.63 μA; while after the working electrode was incubated in aqueous solutions of a single interfering substance, it only caused a slight change in current of 0.21–0.62 μA, corresponding to 1.97%–5.83% of the 6PPD response under the same conditions. It can be seen that the photoelectrochemical sensor has good selectivity.

[0107] Furthermore, when the working electrode was incubated with the mixed solution, the photocurrent decreased by approximately 10.71 μA (for the mixture in the figure), which is almost identical to the signal change after incubation in 1 μM 6PPD aqueous solution, indicating that the photoelectrochemical sensor has good anti-interference performance.

[0108] The results of this embodiment demonstrate that the photoelectrochemical sensor has excellent selectivity and anti-interference performance, enabling highly selective detection of 6PPD in complex environmental matrices.

[0109] In summary, the isothermal titration calorimetry results demonstrate that the host molecule can form a stable inclusion complex with the guest molecule. Molecular docking analysis further reveals that the guest molecule can be completely embedded in the hydrophobic cavity of the host molecule and achieves specific binding through the formation of two stable hydrogen bonds, exhibiting a low binding energy. Proton NMR spectroscopy shows that the host-guest interaction leads to a significant chemical shift in the proton signal, further confirming that the host molecule forms a stable inclusion structure with the guest molecule due to its suitable cavity size and hydrogen bonding. Multiple characterization techniques collectively verify that the host molecule can effectively recognize the guest molecule, providing a solid theoretical basis for constructing a highly selective recognition sensor. Spectroscopic studies revealed significant changes in the UV absorption peak and fluorescence emission spectrum after the host and guest molecules form an inclusion complex. Based on the above host-guest recognition, a fluorescence sensing platform using the host molecule as the recognition unit was further constructed. This system achieved a linear response to 6PPD in the concentration range of 0.01–30 μM, with a detection limit (LOD) as low as 4.13 nM, significantly lower than the EPA-set screening limit for aquatic organisms. A photoelectrochemical sensor based on host molecule recognition was further developed. This sensor has a detection range of 0.01–50 μM and a detection limit of 3.19 nM. This invention is the first to propose and verify that the host molecule serves as a universal recognition element for 6PPD and its conversion product 6PPD-Q, and its molecular recognition mechanism is revealed through multidimensional analysis including ITC, molecular docking, and NMR. Based on this, a fluorescence and electrochemical dual-mode sensing system was constructed, enabling efficient differentiation and sensitive detection of 6PPD and 6PPD-Q. This provides new ideas and technical support for the rapid monitoring and ecological risk assessment of this type of tire-derived pollutant in complex environmental matrices.

[0110] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. The application of at least one of cyclodextrin, functionally modified cyclodextrin, and polycyclodextrin in the detection of 6PPD or 6PPD-Q, wherein, 6PPD is N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine, and 6PPD-Q is N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine-quinone.

2. The application according to claim 1, characterized in that, The functional groups include -NH2, -COOH, -SH, -OH, and -SO3. - At least one of -CH3.

3. The application according to claim 1, characterized in that, The polycyclodextrin is prepared by polymerization, which is selected from one of the following polymerization methods: chemical polymerization, template-directed polymerization, thermally induced polymerization, interfacial polymerization, sol-gel polymerization, and self-assembly polymerization.

4. A fluorescence sensor, characterized in that, The fluorescence sensor includes a recognition element, which includes a recognition material and / or a fluorescently responsive material modified with the recognition material. The recognition material includes at least one of cyclodextrin, functionally modified cyclodextrin, and polycyclodextrin.

5. A photoelectrochemical sensor, characterized in that, The photoelectrochemical sensor includes a working electrode, a counter electrode, and a reference electrode. The working electrode includes a photoactive material modified with a recognition material, wherein the recognition material includes at least one selected from cyclodextrin, functionally modified cyclodextrin, and polycyclodextrin; or, The photoelectrochemical sensor includes a working electrode, a counter electrode, and a reference electrode. The working electrode includes a photoactive layer and a recognition layer modified on the surface of the photoactive layer. The recognition layer includes a recognition material, which includes at least one of cyclodextrin, functionally modified cyclodextrin, and polycyclodextrin. The photoactive layer includes a photoactive material.

6. An electrochemical sensor, characterized in that, The electrochemical sensor includes a working electrode, a counter electrode, and a reference electrode. The working electrode includes an electrocatalytically active material modified with a recognition material, wherein the recognition material includes at least one selected from cyclodextrin, functionally modified cyclodextrin, and polycyclodextrin; or, The electrochemical sensor includes a working electrode, a counter electrode, and a reference electrode. The working electrode includes an electrocatalytic layer and a recognition layer modified on the surface of the electrocatalytic layer. The recognition layer includes a recognition material, which includes at least one of cyclodextrin, functionally modified cyclodextrin, and polycyclodextrin. The electrocatalytic layer includes an electrocatalytically active material.

7. The electrochemical sensor according to claim 6, characterized in that, The electrocatalytic active material includes at least one of graphene, carbon nanotubes, and MOF materials.

8. An electrochemiluminescence sensor, characterized in that, The electrochemiluminescence sensor includes a working electrode, a counter electrode, and a reference electrode. The working electrode includes an electrochemiluminescence material modified with a recognition material, wherein the recognition material includes at least one selected from cyclodextrin, functionally modified cyclodextrin, and polycyclodextrin; or, The electrochemiluminescence sensor includes a working electrode, a counter electrode, and a reference electrode. The working electrode includes an electrochemiluminescence layer and a recognition layer modified on the surface of the electrochemiluminescence layer. The recognition layer includes a recognition material, which includes at least one of cyclodextrin, functionally modified cyclodextrin, and polycyclodextrin. The electrochemiluminescence layer includes an electrochemiluminescence material.

9. The electrochemiluminescence sensor according to claim 8, characterized in that, The electrochemiluminescent material includes at least one of metal complexes, quantum dots, organic small molecule luminescent materials, and polymer luminescent materials.

10. A colorimetric sensor, characterized in that, The colorimetric sensor includes a colorimetric reaction material, a recognition material, and a carrier support material. The recognition material includes at least one of cyclodextrin, functionally modified cyclodextrin, and polycyclodextrin.

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