A black phosphorus-gold / silver nanocomposite-based dual-template molecularly imprinted electrochemical sensor, and a preparation method and application thereof

Abstract

The application discloses a kind of based on black phosphorus-gold / silver nanocomposite double-template molecular imprinting electrochemical sensor and its preparation method and application.The sensor includes modified electrode, the modified electrode includes electrode base, electrode base is sequentially modified with electrode sensitizing material layer and double-template molecular imprinting polymer film layer, electrode sensitizing material layer includes black phosphorus nanoparticle-gold / silver nanoparticle composite material, template is fluroxacin and vancomycin.The electrode of the application can realize the efficient detection of FLE and VA simultaneously through only one interface, this breakthrough design ingeniously uses double-template molecular imprinting technology, embeds specific recognition site in polypyrrole film layer, when template molecule is removed, the cavity left as electrochemical probe enters and adheres to the channel on the surface of BPNS-Au / AgNPs composite substrate, greatly promotes electron transfer efficiency and sensing performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electrochemical sensors, in particular to a black phosphorus-gold / silver nanocomposite dual-template molecularly imprinted electrochemical sensor and a preparation method and application thereof. BACKGROUND

[0002] Fleroxacin (FLE), as a quinolone antibiotic, is widely used in the treatment of respiratory tract, urinary tract, biliary tract infections caused by gram-negative bacteria and chlamydia. However, the abuse of FLE can bring serious health risks, including gastrointestinal dysfunction, central nervous system damage, and allergic reactions when used in excess. On the other hand, Vancomycin (VA), as a representative of glycopeptide antibiotics, is an important drug for the treatment of severe gram-positive bacterial infections, but its high-dose use has potential toxicity to the ear and kidney, and low-dose use can also induce hypersensitivity reactions. Notably, the simultaneous or unreasonable combination of FLE and VA can exacerbate the toxic effects and produce additive negative effects.

[0003] In view of the urgent needs of food safety and environmental protection, it is particularly important to monitor the residual amounts of FLE and VA in animal-derived food and natural environment substrates. Currently, detection techniques for these two antibiotics, such as immunoassay, capillary electrophoresis, and high-performance liquid chromatography, exhibit high sensitivity and accuracy, but are limited by high equipment costs, complex operation procedures, and long analysis periods, limiting their application in a wide range of fields.

[0004] Under this background, electrochemical sensing technology has gradually become a mainstream means for detecting antibiotic residues in the environment due to its rapid response, simple preparation, and high sensitivity. To improve the performance of electrochemical sensors, researchers often use carbon-based nanomaterials, noble metals, transition metal compounds, and conductive polymers to carefully modify the electrodes to enhance their detection capabilities. However, the selectivity challenge faced by traditional electrochemical sensors cannot be ignored, especially the signal interference that may be caused by complex matrices in real samples.

[0005] To overcome this problem, molecularly imprinted polymer (MIPs) electrochemical sensors have emerged, which cleverly combine the high selectivity of molecular imprinting technology with the high efficiency of electrochemical sensing. MIPs electrochemical sensors produce response signals through two main mechanisms: direct measurement of the redox current caused by the binding of target molecules to imprinted sites (suitable for electrochemically active substances such as FLE), or using the "gate effect" principle to detect non-electrochemically active substances (such as VA) by measuring the signal change caused by the entry of probe molecules into the imprinted cavity, thereby achieving compatible detection of a wide range of analytes.

[0006] In view of the electrochemical activity of FLE and the non-electrochemical characteristics of VA, the traditional MIPs electrochemical sensor is still difficult to meet the detection needs of both, and therefore, it is of great significance to develop a new MIPs electrochemical sensor for detecting FLE and VA. SUMMARY

[0007] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application proposes a black phosphorus-gold / silver nanocomposite double-template molecular imprinting electrode, which can be used for simultaneous detection of FLE and VA.

[0008] The present application also proposes a preparation method of the above electrode.

[0009] The present application also proposes a sensor with the above electrode.

[0010] The present application also proposes a preparation method of the above sensor.

[0011] The present application also proposes an application of the above sensor.

[0012] The double-template molecular imprinting modified electrode of black phosphorus-gold / silver nanocomposite according to the first aspect embodiment of the present application, the modified electrode comprises an electrode substrate, the electrode substrate is sequentially modified with an electrode sensitization material layer and a double-template molecular imprinting polymer film layer, and an electrochemical probe is combined in the double-template molecular imprinting polymer film layer, wherein the electrode sensitization material layer comprises black phosphorus nanoparticle-gold / silver nanoparticle composite (BPNS-Au / AgNPs), and the templates of the double-template molecular imprinting polymer film layer are fluroxacin (FLE) and vancomycin (VA).

[0013] The modified electrode according to the embodiment of the present application has at least the following beneficial effects: the present application ingeniously designs a modified electrode integrating a double-signal response mechanism, which can realize efficient detection of FLE and VA at the same time through only one interface, and this breakthrough design ingeniously uses the double-template molecular imprinting technology to embed specific recognition sites in the polypyrrole film layer, and when the template molecules are removed, the cavities left behind enter and adhere to the channels on the surface of the BPNS-Au / AgNPs composite substrate as electrochemical probes, greatly improving the electron transfer efficiency and sensing performance.

[0014] The BPNS-Au / AgNPs as the enhancement material of the electrode substrate not only enhances the electron conduction ability by virtue of the unique nanostructure, but also effectively anchors the target analyte by virtue of the excellent catalytic activity and large specific surface area, so as to significantly improve the detection sensitivity of the sensor. The synergistic mechanism between the BPNS-Au / AgNPs and the dual-template molecularly imprinted film makes the sensor exhibit excellent sensitivity, selectivity and stability in the detection of FLE and VA in a wide concentration range (0.001 μM to 10 μM).

[0015] Specifically, for FLE, the sensor exhibits two linear detection intervals: a low concentration interval (1 nM to 1 μM) and a high concentration interval (1 μM to 10 μM), and the detection lower limit (LOD) is as low as 0.25 nM, which fully proves the high sensitivity. For VA, the sensor exhibits a good linear response in the entire detection range (0.001 μM to 10 μM), and the LOD is as low as 0.17 nM, which further highlights the excellent detection performance.

[0016] In addition, the modified electrode (MIP / BPNS-Au / AgNP / GCE) also performs well in practical applications, and can accurately detect FLE and VA in sewage and milk samples, and the recovery rates are stably between 91.17% and 107.97% and between 91.91% and 104.83% respectively, which fully verifies the practicability and reliability of the modified electrode in the actual environmental monitoring and food safety detection.

[0017] In summary, the dual-template molecularly imprinted electrochemical sensing platform of the application exhibits a broad application prospect in the fields of environmental monitoring, food safety analysis and the like, owing to the rapid response, simple operation, high cost-effectiveness and excellent detection performance, and opens up a new direction for the development of electrochemical sensing technology.

[0018] According to some embodiments of the application, the electrochemical probe contains at least one of methylene blue, ferrocene or [Fe(CN)6] 3- / 4- According to some embodiments of the application, the electrode substrate is at least one of a glassy carbon electrode (GCE), a screen-printed carbon electrode (SPCE) or a gold electrode.

[0019] According to some embodiments of the application, the polymer film layer is at least one of a polypyrrole film layer, a polyaniline film layer, a polythiophene film layer, a polydopamine film layer or a poly-o-phenylenediamine film layer.

[0020] The preparation method of the modified electrode according to the second aspect of the embodiments of the application comprises the following steps:

[0021] S1, preparing black phosphorus nanoparticle-gold / silver nanoparticle composite material: chloroauric acid is mixed with black phosphorus, and reacted under ultraviolet light irradiation, and the solid phase part I is collected by solid-liquid separation, the solid phase part I is prepared into a dispersion liquid I, and a silver salt is added, the silver salt is dispersed in the dispersion liquid I, and reacted again under ultraviolet light irradiation, and the solid phase part II is collected by solid-liquid separation again, and the black phosphorus nanoparticle-gold / silver nanoparticle composite material is obtained;

[0022] S2, the black phosphorus nanoparticle-gold / silver nanoparticle composite material is prepared into a dispersion liquid II, and the dispersion liquid is formed into an electrode sensitization material layer on an electrode substrate;

[0023] S3, the functional monomer and the template molecule are formed into a double-template molecule imprinted polymer film layer on the surface of the electrode sensitization material layer by electro-polymerization;

[0024] S4, the template is removed by elution, and the double-template molecule imprinted polymer film layer is combined with the electrochemical probe on the surface of the modified electrode in an electrochemical probe solution, and the modified electrode is obtained;

[0025] The template molecule is a mixture of fluroxacin and vancomycin.

[0026] The preparation method according to the embodiment of the application has at least the following beneficial effects: the preparation method of the application scheme is simple to operate and has good application prospects. The application scheme utilizes effective irradiation of ultraviolet light to promote the generation of a large number of active electron-hole pairs in the black phosphorus nanoparticle (BPNS). This process not only enriches the surface free electron density of the black phosphorus nanoparticle (BPNS) and significantly enhances its reduction capacity, but also endows BP with the dual role of a noble metal photocatalyst and an ideal substrate. The application scheme is ingenious in that, through fine regulation and control of ultraviolet light, BP self-optimization and the composite of noble metal nanoparticles (such as gold nanoparticles AuNPs and silver nanoparticles AgNPs) are realized, and a BPNS-Au / AgNPs bimetallic nanocomposite material is formed. The composite material provides a large number of active sites for efficient anchoring of target molecules due to its increased specific surface area, and thus greatly improves the sensitivity of the detection system.

[0027] Further, the application innovatively introduces BPNS-Au / AgNPs as an electrode sensitization material into the field of electrochemical sensing, selects pyrrole as a functional monomer, and accurately constructs a double-template molecular imprinting film on the surface of a BPNS-Au / AgNPs modified glassy carbon electrode (GCE) through an electro-polymerization technology. The film structure can specifically recognize and capture target analytes such as FLE and VA, and simultaneously combines with a high-sensitivity electrochemical probe technology to realize high-selectivity and high-sensitivity detection of the two compounds. This scheme not only widens the application range of black phosphorus nanomaterials in electrochemical sensing, but also provides a new idea and technical means for rapid and accurate detection of small molecule substances in complex biological systems.

[0028] According to some embodiments of the application, in the step S1, the molar ratio of chloroauric acid to silver salt is 0.5-2:1. For example, 1:1.

[0029] According to some embodiments of the application, in the step S1, the molar ratio of black phosphorus to chloroauric acid is 10:15-25.

[0030] According to some embodiments of the application, in the step S1, the reaction condition under the irradiation of ultraviolet light includes at least one of the following conditions: 1) the wavelength of ultraviolet light is 360-370 nm; 2) the time is 50-70 min; 3) the ultraviolet light is emitted by an ultraviolet lamp, and the power of the ultraviolet lamp is 45-55 W.

[0031] According to some embodiments of the application, in the step S1, the reaction condition under the irradiation of ultraviolet light includes at least one of the following conditions: 1) the wavelength of ultraviolet light is 365 nm; 2) the time is 60 min; 3) the ultraviolet light is emitted by an ultraviolet lamp, and the power of the ultraviolet lamp is 50 W.

[0032] According to some embodiments of the application, in the step S1, the reaction condition under the irradiation of ultraviolet light includes at least one of the following conditions: 1) the wavelength of ultraviolet light is 360-370 nm; 2) the time is 80-100 min; 3) the ultraviolet light is emitted by an ultraviolet lamp, and the power of the ultraviolet lamp is 45-55 W.

[0033] According to some embodiments of the application, in the step S1, the reaction condition under the irradiation of ultraviolet light includes at least one of the following conditions: 1) the wavelength of ultraviolet light is 365 nm; 2) the time is 90 min; 3) the ultraviolet light is emitted by an ultraviolet lamp, and the power of the ultraviolet lamp is 50 W.

[0034] According to some embodiments of the application, in the step S3, the molar ratio of the functional monomer, fluroxacin and vancomycin is 0.25-4:1:1.

[0035] According to some embodiments of the present application, the functional monomer is at least one of pyrrole, aniline, thiophene, dopamine, and o-phenylenediamine.

[0036] According to some embodiments of the present application, the number of electro-polymerization cycles is 5-15 cycles. Preferably, the number of cycles is 10 cycles.

[0037] According to some embodiments of the present application, the template is eluted by electrochemical elution. Specifically, the number of CV cycles in the CV scan for eluting the dual-template is more than 60 cycles. Preferably, the number of CV cycles is 60 cycles, which is stable and thus more energy-saving.

[0038] According to some embodiments of the present application, the electrochemical probe is combined with the surface of the dual-template molecularly imprinted polymer film layer by cyclic voltammetry scanning in step S4.

[0039] According to some embodiments of the present application, the cyclic voltammetry scanning is performed until the redox peak current in the cyclic voltammetry curve changes by less than 2%.

[0040] According to some embodiments of the present application, the electrochemical probe solution is 2-3 mmol / L of [Fe(CN)6] 3- / 4- solution.

[0041] According to some embodiments of the third aspect of the present application, the sensor comprises an electrode system and a supporting electrolyte solution.

[0042] According to some embodiments of the present application, the sensor further comprises a reference electrode and an auxiliary electrode.

[0043] According to some embodiments of the present application, the reference electrode is a saturated calomel electrode or an Ag / AgCl electrode.

[0044] According to some embodiments of the present application, the auxiliary electrode is a platinum wire.

[0045] According to some embodiments of the fourth aspect of the present application, the preparation method comprises the step of preparing the modified electrode by the above-mentioned preparation method of the modified electrode.

[0046] According to some embodiments of the present application, the preparation method further comprises the step of assembling the sensor by using the auxiliary electrode, the reference electrode, and the supporting electrolyte solution.

[0047] According to some embodiments of the present application, the supporting electrolyte comprises a phosphate buffer.

[0048] According to some embodiments of the present application, the concentration of the phosphate buffer in the supporting electrolyte solution is 0.08-0.12 mol / L, such as 0.1 mol / L.

[0049] According to some embodiments of the present invention, the pH of the supporting electrolyte solution is 4 to 7, such as 4, 5, 6, or 7.

[0050] According to the fifth aspect of the present invention, the above-described sensor is used in detecting FLE and / or VA.

[0051] The application according to a fifth aspect of the present invention also includes a method for detecting antibiotics using the above-described sensor, comprising the steps of: incubating the modified electrode in a solution containing a supporting electrolyte and an antibiotic, employing a dual-signal strategy, with [Fe(CN)6] as the signal. 3- / 4- An electrochemical probe is used to detect the antibiotic by voltammetry; wherein the antibiotic includes fleroxacin (FLE) and / or vancomycin (VA), and the voltammetry is one of linear sweep voltammetry (LSV), differential pulse voltammetry (DPV), and square wave pulse voltammetry (SWV).

[0052] According to some embodiments of the present invention, the incubation time is 6 to 10 minutes.

[0053] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0054] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0055] Figure 1 This is a schematic diagram of the preparation route of the modified electrode in an embodiment of the present invention;

[0056] Figure 2 The following figures represent the characterization results of the raw materials, intermediate products, and finished products of the modified electrodes in this embodiment of the invention: TEM images of BPNS (A) and BPNS-Au / AgNP (B); HAADF-STEM image (CF) of BPNS-Au / AgNP; XRD patterns (G), Raman spectra (H), and XPS spectra (I) of BPNS and BPNS-Au / AgNP.

[0057] Figure 3 These are AFM images of the modified electrodes prepared in the embodiments and comparative examples of the present invention before and after elution: AFM images of MIP / BPNS-Au / AgNP / GCE before elution (A), after elution (B), and NIP / BPNS-Au / AgNP / GCE before elution (C), after elution (D).

[0058] Figure 4is the parameter optimization test result graph in the preparation and application process of the modified electrode of the embodiment of the present application: analysis of the optimization of parameters, the influence of the loading amount (A) of BPNS-Au / AgNPs, the number of electro-polymerization cycles (B), the molar ratio of VA:FLE:Py (C), elution cycles (D), and incubation time (E) on the i pa of 10 μM VA and the relationship between the i pa of 10 μM FLE and pH value (F); the LSV curve (G) of 10 μM FLE and the i pa or E pa and pH value (H).

[0059] Figure 5 is the cyclic voltammogram (A, B) and Nyquist curve (C, D) of different electrodes in 0.1M KCl containing 5mM [Fe(CN)6] 3- / 4- of the embodiment and the comparative example of the present application.

[0060] Figure 6 is the peak current of 10 μM FLE and VA measured on different electrodes in the test example of the present application.

[0061] Figure 7 is the CV curve (A), i pa and v (B), the linear relationship graph (D) between log(i pa ) and log(v) (C), E pa and lnv, and the electrochemical mechanism (E) of FLE oxidation on MIP / BPNS-Au / AgNP / GCE obtained by the test example of the present application.

[0062] Figure 8 is the LSV curve (A) of MIP / BPNS-Au / AgNP / GCE prepared in the embodiment of the present application after incubation in different concentrations of VA (0.001-10 μM) and the linear relationship graph (B) between the anode peak current and the concentration in the range of 0.001-10 μM, the LSV curve (C) of MIP / BPNS-Au / AgNP / GCE after incubation in different concentrations of FLE (0.001-10 μM), and the calibration curve of FLE concentration change (D) and FLE peak current (E) with potassium ferricyanide current.

[0063] Figure 9The peak current (A) of LSV corresponding to the MIP / BPNS-Au / AgNP / GCE prepared in the embodiment of the present application incubated with 1 μM double template and environmental interferent, and the peak current (B) of LSV incubated with the same concentration of interferent (1:1) as the target analyte.

[0064] Figure 10 The column chart of the peak current response of 1 μM target analyte (A) measured seven times in succession in the same MIP / BPNS-Au / AgNP / GCE, the peak current response of 1 μM target analyte (B) recorded in five independent MIP / BPNS-Au / AgNP / GCE, and the peak current response of target analyte (C) within 28 days in the test example of the present application.

[0065] Figure 11 The linear relationship chart of MIP / BPNS-Au / AgNP / GCE incubated in sewage (A) and milk (B) added with different concentrations of FLE (0.1-1 μM), and the linear relationship chart of MIP / BPNS-Au / AgNP / GCE incubated in sewage (C) and milk (D) added with different concentrations of VA (0.1-1 μM) in the embodiment of the present application. DETAILED DESCRIPTION

[0066] The embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary only, and are for the purpose of explanation only, and are not to be construed as limiting the present application.

[0067] In the description of the present application, it is to be understood that if I, II are described, it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the sequence of the indicated technical features.

[0068] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0069] The purity and manufacturer information of some reagents used in the following examples, comparative examples and test examples are shown in Table 1 below:

[0070] Table 1

[0071]

[0072]

[0073] The model specifications and manufacturer information of the instruments used in the following test examples are shown in Table 2 below:

[0074] Table 2

[0075]

[0076] Example

[0077] In this example, a dual-template molecularly imprinted modified electrode (MIP / BPNS-Au / AgNP / GCE) based on black phosphorus-gold / silver nanocomposite material is prepared. The modified electrode comprises an electrode substrate, and an electrode sensitizing material layer and a dual-template molecularly imprinted polymer film layer are sequentially modified on the electrode substrate, and an electrochemical probe is combined in the dual-template molecularly imprinted polymer film layer. The electrode sensitizing material layer is made of BPNS-Au / AgNPs composite material, and the templates of the dual-template molecularly imprinted polymer film layer are FLE and VA.

[0078] The preparation route thereof is shown in Figure 1 The specific preparation process is as follows:

[0079] 1) Preparation of BPNS-Au / AgNPs: 1 mL of HAuCl4·4H2O (10 mM) was dispersed into 2 mL of black phosphorus crystals (300 μg / mL, 100-500 μg / mL can be used), and ultrasonic treatment was performed for 10 min. The mixed solution was irradiated with an ultraviolet lamp (365 nm, 50 W) for 1.0 h. Centrifugation was performed at a speed of 10 000 r / min for 6 min to obtain a precipitate. The obtained precipitate was dispersed in 2 mL of DIW (deionized water) to obtain a BPNS-AuNPs dispersion. Then, 1 mL of AgNO3 (10 mM) solution was dispersed in 2 mL of BPNS-AuNPs, ultrasonic treatment was performed for 10 min, and the solution was irradiated with an ultraviolet lamp (365 nm, 50 W) for 1.5 h. Centrifugation was performed at a speed of 10 000 r / min for 6 min to obtain a precipitate, and the obtained precipitate was again dispersed in 1 mL of DIW and stored in a 4°C refrigerator for standby.

[0080] 2) Preparation of MIP / BPNS-Au / AgNP / GCE: Before electrode modification, the glassy carbon electrode (GCE, 3.0 mm in diameter) was pretreated (the glassy carbon electrode was polished with 0.5, 0.3, and 0.05 μm Al2O3 powder on a leather pad in turn, and then cleaned with ultrapure water, anhydrous ethanol, and ultrapure water in turn under ultrasonic, and dried with nitrogen (or infrared lamp radiation drying or natural drying can also be used). First, 4 μL of BPNS-Au / AgNPs was dropped on the surface of the GCE, and after drying, BPNS-Au / AgNP / GCE was obtained. Subsequently, 15 cycles of CV scanning were performed in a water solution containing 10 mM VA, 10 mM FLE, and 10 mM Py (VA:FLE:PY = 1:1:1) at a potential range of 0-1.5 V at a scan rate of 100 mV s -1 . Electrochemical elution was then used to remove the template. That is, a continuous CV scan was applied to the obtained electrode in 0.1 M NaOH (potential range: -1.0-+1.0 V; scan rate: 100 mV s -1 ) until obvious and stable redox peaks appeared in the probe solution (2.5 mM [Fe(CN)6] 3- / 4- ) (the change in redox peak current was less than 2%), and MIP / BPNS-Au / AgNP / GCE was obtained.

[0081] The above modified electrode, a saturated calomel electrode, and a platinum wire were constructed into an electrode system, and 0.1 M PBS solution (pH = 5) was used as a supporting electrolyte to construct an electrochemical sensor.

[0082] The above sensor was used to detect antibiotics, and the operation process was as follows:

[0083] The above modified electrode was incubated in a solution containing a supporting electrolyte and antibiotics, and a double-signal strategy was used to detect the antibiotics by voltammetry with [Fe(CN)6] 3- / 4- as an electrochemical probe; wherein the antibiotics included FLE and / or VA, and the voltammetry could be any one of LSV, DPV, and SWV, and in this embodiment, LSV was specifically used.

[0084] Comparative Example

[0085] In this example, a modified electrode (NIP / BPNS-Au / AgNP / GCE) based on a black phosphorus-gold silver nanocomposite non-molecularly imprinted polymer was prepared, and the difference from the embodiment was that no template molecule was added during electro-polymerization.

[0086] The above modified electrode was constructed into a sensor based on the same method in the embodiment.

[0087] Test Example

[0088] The performance of the electrodes prepared in the examples and test examples was characterized and tested.

[0089] 1) Morphology characterization

[0090] The structure and morphology of the black phosphorus crystal and BPNS-Au / AgNPs composite material were characterized by TEM, EDS, XRD, XPS, and Raman spectrometer. The results are shown in Figure 2 .

[0091] As can be seen from Figure 2 , the black phosphorus crystal presents a typical layered structure and a smooth surface, with a diameter of about 200 nm. TEM of BPNS-Au / AgNPs can observe that the spherical Au / AgNPs with a particle size of about 50 nm are uniformly loaded on the layered surface of BPNS Figure 2 B). Element mapping Figure 2 C-F) of BPNS-Au / AgNPs can observe that Ag, Au, P, and O elements are uniformly distributed. XRD of BPNS and BPNS-Au / AgNPs is shown in Figure 2 G. BPNS appears three characteristic diffraction peaks at 16.9°, 34.2°, and 52.3°, which are respectively attributed to the (020), (040), and (060) crystal planes of orthorhombic BP (JCPDS #73-1358). BPNS-Au@AgNPs, in addition to the three characteristic diffraction peaks of BP, can also observe four additional diffraction peaks at 38.2°, 44.3°, 64.7°, and 77.5°, which are respectively attributed to the (111), (200), (220), and (311) crystal planes of Au@AgNPs, confirming that Au / AgNPs are successfully anchored on the surface of BPNS. Figure 2 H is the Raman spectrum of BP crystal, BPNS, and BPNS-Au@AgNP. BP crystal appears obvious characteristic peaks at 361, 437, and 465 cm -1 , which are respectively corresponding to the in-plane vibration mode A 1g and the out-of-plane vibration mode B2g and A 2g . Compared with the BP crystal, the three characteristic peaks of BPNS are slightly red-shifted by about 2 cm -1 . Studies have shown that BP exhibits obvious anisotropic electron-phonon interaction, and the Raman characteristic peak position is closely related to the polarization, wavelength, and thickness. Therefore, the red shift of the characteristic Raman peak of BPNS indicates that the BP crystal is successfully exfoliated into few-layered BPNS. Figure 2 I is the XPS spectrum of BPNS and BPNS-Au@AgNP. In the P 2p fine spectrum of BPNS, 2p 3 / 2 and 2p 1 / 2a broad peak at 133.8 eV, which might be attributed to P 2p from the surface of BPNSs x O y This indicates that BP is slightly oxidized during the stripping process. BPNS-Au@AgNPs show two sharp peaks at 87.03 and 83.33 eV, which are attributed to Au 4f 5 / 2 and 4f 7 / 2 ; Ag 3d fine spectra also show two sharp peaks at 373.51 and 367.51 eV, which are mainly related to Ag 0 3d 3 / 2 and 3d 5 / 2 . Meanwhile, the peaks of P 2p 1 / 2 and 2p 3 / 2 exhibit a slight red shift (about 0.2 eV), which might be due to the electron transfer from BP with a higher Fermi level to noble metal NPs. The potential mechanism might be due to the redox reaction between BP and noble metal ions. The work function of BP is related to the thickness, and the Fermi level of BP is much higher than the reduction potential of AuCl4 - and Ag + . Therefore, BP / AuCl4 - , BP / Ag + can form a redox couple, and the electron spontaneously transfers from BP to AuCl4 - and Ag + , thus generating AuNPs and AgNPs. It is worth noting that the intensity of P x O y characteristic peaks in BPNS-Au / AgNPs is obviously decreased compared with BPNS, indicating that Au / AgNPs significantly improve the stability of BPNS. In summary, BPNS-Au / AgNP contains Au 4f, Ag 3d and P 2p characteristic peaks, indicating that Au and Ag exist on the BP matrix at the same time.

[0092] The morphology of MIPs and NIPs before and after the removal of templates was analyzed by AFM. As shown in Fig. Figure 3 A, the roughness of MIPs film is larger (Ra=23.1 nm) in the presence of dual-template molecules; in the absence of dual-template molecules, a relatively dense and less rough film is formed on the surface of NIPs, and the average roughness Ra is 16.7 nm (Fig. Figure 3 C). As shown in Fig. Figure 3 B, the roughness of MIPs is enhanced (average roughness Ra=46.1 nm) after elution of FLE and VA from MIPs, indicating that imprint cavities are formed in the MIP film. For NIP, the roughness of NIP film is almost unchanged (Ra=21.0 nm, Fig. Figure 3 D) after "template removal".

[0093] 2) Parameter optimization analysis in the preparation process

[0094] 2.1 BPNS-Au / AgNPs loading amount

[0095] Figure 4 A is the effect of BPNS-Au / AgNPs loading amount on the anodic oxidation peak current (i pa (FLE)) of FLE. With the increase of BPNS-Au / AgNPs loading amount from 2 μL to 4 μL, the electrode surface is continuously covered by BPNS-Au / AgNPs, so i pa (FLE) also increases. However, when the BPNS-Au / AgNPs loading amount exceeds 4 μL, the BPNS-Au / AgNPs of the sensing layer is too thick, which seriously hinders the electron transfer, and i pa (FLE) instead sharply decreases. Therefore, the loading amount of BPNS-Au / AgNPs is preferably 4 μL.

[0096] 2.2 Number of electro-polymerization cycles

[0097] The number of electro-polymerization cycles is an important parameter in the electro-polymerization process, which is directly related to the thickness of the MIP film. Therefore, the thickness of the MIP film can be regulated by the number of electro-polymerization cycles. As shown in FIG. Figure 4 B, i pa (FLE) and Δi pa ([Fe(CN)6] 3- ) both reach the maximum when the electro-polymerization cycle is 10; when the electro-polymerization cycle exceeds 10, i pa (FLE) and Δi pa ([Fe(CN)6] 3- ) sharply decrease. With the continuous increase of the electro-polymerization cycle, the thickness of the MIP film continuously increases, and the number of imprint cavities that can be carried also increases, so i pa (FLE) and Δi([Fe(CN)6] 3- ) both continuously increase. Too many electro-polymerization cycles will result in a too thick MIP film, thereby increasing the electron transfer resistance, leading to the decrease of i pa (FLE) and Δi pa ([Fe(CN)6] 3- ). Therefore, the optimal electro-polymerization cycle is 10.

[0098] 2.3 Template: monomer ratio

[0099] The binding strength of the template and the MIP is highly related to the ratio of the two templates and the functional monomers. Figure 4 C is the effect of different VA:FLE:Py on i pa (FLE) and Δi pa ([Fe(CN)6] 3-) of the MIPs. VA:FLE:Py was in the range of 1:1:0.25 to 1:1:4, i pa ([Fe(CN)6] 3- ) reached the maximum at 1:1:1. When the concentration of the functional monomer was low, the MIP film was thin, and the number of imprinted cavities was very limited, which resulted in a weak adsorption ability of the imprinted cavities to the template. However, a high concentration of Py led to a thick MIP film, which resulted in poor conductivity of the MIP film and difficulty in removing the template embedded in the MIP, thus decreasing the specific recognition ability of the MIP to the template. Therefore, the optimal molar ratio of VA:FLE:Py was 1:1:1.

[0100] 2.4 Template elution

[0101] After the electro-polymerization of the MIP, the template was embedded in the imprinted cavities. In this chapter, the electrochemical elution strategy was used to elute the double template by CV scanning. Obviously, the number of CV scanning cycles directly affected the template removal effect. After the template elution, the diffusion of [Fe(CN)6] 3- / 4- and the subsequent redox were significantly enhanced. Therefore, the change in Δi pa ([Fe(CN)6] 3- ) before and after the elution (Δi pa ([Fe(CN)6] 3- )) could well evaluate the template removal efficiency. As shown in Figure 4 D, with the increase in the number of CV scanning cycles from 30 to 60, Δi(Fe(III)) continuously increased, and after 60 cycles, Δi pa ([Fe(CN)6] 3- ) tended to be stable, indicating that the template removal was complete or the template removal had reached the limit. Therefore, the optimal number of CV scanning cycles for the electrochemical elution of the template was 60.

[0102] 2.5 Incubation time

[0103] As shown in Figure 4 E, with the extension of the incubation time, i pa (FLE) on the MIP / BPNS-Au / AgNP / GCE gradually increased and reached the maximum at 7 min, and then tended to be saturated. This indicated that the imprinted cavities in the MIP film gradually combined with the template, and the combination of the template and the imprinted cavities reached saturation after 7 min. Therefore, the optimal incubation time was set to 7 min.

[0104] 2.6 pH of the supporting electrolyte solution

[0105] Figure 4 F is the corresponding Δi pa ([Fe(CN)6] 3-) with pH, it can be seen that Δi([Fe(CN)6] 3- ) gradually increased and reached a maximum at pH 5.0. Figure 4 G is the LSV curve of FLE at different buffer pH (2.0-8.0), and the corresponding i pa (FLE) with pH is shown in Figure 4 H. With the continuous increase of pH, the anodic peak potential of FLE is continuously negatively shifted, indicating that protons (H + ) are involved in the oxidation of FLE. With the increase of pH of the supporting electrolyte solution from 2.0 to 5.0, i pa (FLE) gradually increased and reached a maximum at pH 5.0; with the continuous increase of pH, i pa (FLE) instead sharply decreased. Therefore, the optimal pH of the supporting electrolyte solution was set to 5.0. The anodic peak potential (E pa ) of FLE showed a good linear correlation with the buffer pH, and the linear regression equation was E pa (V) = -0.06715pH + 1.377 (R 2 = 0.9995) ( Figure 4 G). The slope (-67.15 mV pH -1 ) is close to the Nernst theoretical value (-59.2 mV pH -1 ), indicating that the oxidation of FLE involves equal electron and equal proton transfer.

[0106] 3) Electrochemical performance test

[0107] The CV and electrochemical impedance spectroscopy (EIS) of different electrodes were recorded in 2.5 mM [Fe(CN)6] 3- / 4- redox probe solution to characterize their electrochemical performance. LSV was used to quantitatively detect FLE and VA, and the specific test method was as follows: under stirring, MIP / BPNS-Au / AgNP / GCE was incubated in a mixed solution of different concentrations of VA and FLE (VA:FLE = 1:1) for 7 min, and then MIP / BPNS-Au / AgNP / GCE was transferred to 2.5 mM [Fe(CN)6] 3- / 4- , and the LSV curve of -0.2-1.4 V was recorded at a scan rate of 100 mV s -1 .

[0108] 3.1 Electrochemical behavior of [Fe(CN)6] 3- / 4- on modified electrode

[0109] 5 mM [Fe(CN)6] 3- / 4-The stepwise construction process of BPNS-Au / AgNP / GCE was investigated by CV in 0.1M KCl solution (e.g. Figure 5 As shown in Figure A). [Fe(CN)6] was observed in the bare GCE. 3- / 4- A pair of symmetrical redox peaks, i pa and i pc The values ​​were 138.6 μA and -134.6 μA, respectively. When GCE was modified with BPNSs, i pa and i pc The increases to 142.4 and -144.4 μA, respectively, are likely due to the improved electron transfer induced by BPNSs. When GCE is modified with BPNS-Au / AgNPs, its i pa and i pc All showed a significant increase (i pa =204μA;i pc =-184.1μA), which may be due to the improved stability of black phosphorus by Au / AgNPs, and the synergistic effect of BPNS and Au / AgNPs improving catalytic activity.

[0110] Due to the electron transfer blockade of the PPy matrix, [Fe(CN)6] 3- / 4- The redox peaks on MIP / BPNS-Au / AgNP / GCE almost disappeared (e.g.) Figure 5 (As shown in B). After eluting the template, a pair of sharp redox peaks appeared (i). pa =126.5μA; i pc =-117.1 μA), because the imprinted cavity promotes [Fe(CN)6] 3- / 4- The diffusion and redox processes indirectly confirmed the efficient elution of the template from the PPy membrane. After incubation in 10 μM VA and FLE, [Fe(CN)6]... 3- / 4- i pa and i pc Significantly reduced (i pa =100.1μA; i pc =-103.5μA), possibly because FLE binds to VA in the imprinted cavity, suppressing [Fe(CN)6]. 3- / 4- The diffusion and redox processes. Furthermore, the voltammetric response on MIP / BPNS-Au / AgNP / GCE is significantly higher than that on MIP / GCE(i pa =89.43μA;i pc = -82.71 μA), indicating that BPNS-Au / AgNP, with its large surface area, can accommodate more imprinted sites. Conversely, due to the lack of effective imprinted sites, no obvious redox peaks were observed on NIP / BPNS-Au / AgNP / GCE.

[0111] Figure 5 C, D show the Nyquist plots of different electrodes at open circuit voltage. After BPNS-Au / AgNPs modified GCE, R ct significantly decreased, indicating that BPNS-Au / AgNP has good conductivity. When imprint PPy film is coated on BPNS-Au / AgNP, R ct significantly increased. This is mainly due to the poor conductivity of MIP film, which hinders the transmission of electrons from the solution to the electrode. After removing the template, R ct of MIP / BPNS-Au / AgNP / GCE decreased, which proved that the template molecules had been effectively removed from the MIP film, and the imprinting cavity enhanced the porosity of MIP, thus promoting the diffusion and redox reaction of [Fe(CN) 3- / 4- ]6. In contrast, NIP / BPNS-Au / AgNP / GCE showed the largest semicircle compared to the MIP counterpart, which is due to the quite large electronic transmission barrier of compact and non-conductive NIP film. The results are consistent with the CV current response trend.

[0112] 3.2 Electrochemical responses of FLE and VA on different modified electrodes

[0113] LSV was used to record the anodic peak current changes of FLE and [Fe(CN) 3- / 4- ]6on different electrodes to evaluate their detection performance for FLE and VA (as shown in Figure 6 Due to slow electrode kinetics, the anodic peak of FLE on bare electrode is very weak (Δi pa (FLE) = 0.2533 μA) and Δi pa ([Fe(CN) 3- ]6) is 0.01667 μA. Both Δi pa (FLE) (0.3080 μA) and Δi pa ([Fe(CN) 3- ]6) (0.05200 μA) on BPNS / GCE increased, which may be due to the improvement of BPNSs in electron transfer. When BPNS-Au / AgNP modified GCE, Δi pa (FLE) and Δi pa ([Fe(CN) 3- ]6) increased to 0.5997 μA and 0.07167 μA, respectively, which is mainly due to the improvement of Au / AgNP functionalization in the stability and electrocatalytic activity of BPNS. When imprint PPy film modified GCE, BPNS / GCE, BPNS-Au / AgNP / GCE, respectively, its Δi pa (FLE) and Δi pa ([Fe(CN)3- The adsorption and specific recognition capabilities of the imprinted PPy membranes significantly increased to 1.730 μA / 0.07900 μA, 2.172 μA / 0.1277 μA, and 9.179 μA / 1.170 μA, primarily due to the strong adsorption capacity and specific recognition ability of the Δi membrane. pa (FLE) and Δi pa (Fe(III)) reaches its maximum at all MIP / BPNS-Au / AgNP / GCE, approximately four times that of MIP / GCE, Δi pa ([Fe(CN)6) 3- The value is approximately 14 times that of MIP / GCE. The Δi of NIP / BPNS-Au / AgNP / GCE pa (FLE) and Δi pa ([Fe(CN)6) 3- ) are all relatively small (Δi) pa (FLE) = 0.705 μA; Δi pa ([Fe(CN)6) 3- The NIP film has a conductivity of 0.05067 μA, which is significantly lower than that of MIP / BPNS-Au / AgNP / GCE. This may be due to the poor conductivity and lack of imprinted sites on the NIP film, which severely hinders electron transfer.

[0114] 3.3 Electrochemical oxidation mechanism of FLE

[0115] To elucidate the electrochemical oxidation mechanism of FLE in MIP / BPNS-Au / AgNP / GCE, after incubation in 10 μM FLE, the samples were incubated in 0.1 M PBS (pH = 5) at different v (20-220 mV s). -1 Record the CV curve of FLE ( Figure 7 A). As v increases, the anodic peak of the FLE continuously shifts positively, and the peak current gradually increases. Furthermore, no obvious cathode peak was observed during reverse scanning, indicating that the redox reaction of the FLE on MIP / BPNS-Au / AgNP / GCE is irreversible. Figure 7 As shown in B, the peak current of the FLE is related to the v height (i pa (μA)=0.1449v(mV s -1 +0.01156, R 2 =0.9999), and i pa The double logarithmic graph of v approximates a straight line. Figure 7 C), with a slope of 1.001, indicates that FLE oxidation is adsorption-controlled. Furthermore, the E of FLE... pa As lnv increases linearly ( Figure 7 D), the linear regression equation is E pa (V)=0.03842ln(v / mV s-1 )+0.7855, R 2 =0.9935. For irreversible electrochemical reactions, the charge transfer coefficient (α) is generally assumed to be 0.5. Combining the Laveron equation, the number of electrons transferred (n) during FLE oxidation is approximately 1. As described in Section 4.3.2, the number of protons and electrons involved in FLE electrochemical oxidation is equal. Therefore, it is speculated that FLE oxidation involves 1 electron and 1 proton. The possible FLE oxidation mechanism of MIP / BPNS-Au / AgNP / GCE is as follows: Figure 7 As shown in E.

[0116] 3.4 Linear Response Range and Detection Limit

[0117] Under optimal conditions, Δi on MIP / BPNS-Au / AgNP / GCE at different concentrations of FLE or VA was recorded by LSV. pa (FLE) and Δi pa ([Fe(CN)6) 3- Quantitative analysis of FLE and VA content. For example... Figure 8 As shown in A and 8B, Δi pa ([Fe(CN)6) 3- The concentration of vitamin A (VA) decreased with increasing concentration, as shown in the standard curves for 0.001–1.0 μM and 1.0–10 μM. pa (μA)=0.3172C(μM)-0.6777(R) 2 =0.9901) and i pa (μA)=0.05108C(μM)-0.9441(R 2 =0.9898), the linear detection range is 0.001–10 μM, and the LOD (3σ / S, where σ is the standard deviation of 7 consecutive blank tests and S is the slope of the standard curve at lower concentrations) is 0.17 nM. As the FLE concentration increases, i pa (FLE) gradually increases, while Δi pa (Fe(III)) significantly decreased ( Figure 8 C). Within the range of 0.001–10 μM, Δi pa ([Fe(CN)6) 3- The relationship between the concentration of FLE and the concentration of FLE is linear. Figure 8 D), its standard curve is i pa (μA)=0.1144C(μM)-0.5347(R) 2 =0.9901); i pa (FLE) also showed a linear correlation with FLE concentration in the range of 0.001-10 μM. Figure 8 E), its standard curve is i pa(μA)=4.350C(μM)+1.416(R 2 =0.9984) and i pa (μA)=0.6697C(μM)+5.143(R 2 =0.9976). The LOD of FLE is 0.25 nM (S / N = 3). These results indicate that MIP / BPNS-Au / AgNP / GCE can simultaneously detect the non-electroactive substance VA and the electroactive substance FLE.

[0118] 3.5 Anti-interference capability test

[0119] To verify the anti-interference capability of MIP / BPNS-Au / AgNPs / GCE, after incubation with 1 μM FLE and potential interfering substances present in VA structural analogs or actual samples, Δi was recorded. pa (FLE) and Δi pa ([Fe(CN)6) 3- ).like Figure 9 The results showed that no obvious anodic peaks were detected after incubation with 1 μM of each interfering substance. To further evaluate the anti-interference ability of MIP / BPNS-Au / AgNP / GCE, Δi was also recorded under coexistence with the same concentration of potential interfering substances. pa (FLE) and Δi pa ([Fe(CN)6) 3- Their relative errors are all less than 5%, indicating that FLE and VA preferentially bind to the imprinted cavity. These results confirm that MIP / BPNS-Au / AgNP / GCE has strong anti-interference capabilities.

[0120] 3.6 Repeatability, Reproducibility and Stability Tests

[0121] For reuse, after each detection, the modified electrode was immersed in 0.1M NaOH solution and 20 consecutive CV scans were applied (potential range: -1.0 to +1.0 V; scan rate: 100 mV s). -1 To remove the bound dual-template molecules VA and FLE, the reproducibility, repeatability, and stability of MIP / BPNS-Au / AgNP / GCE were evaluated to verify its practicality. Figure 10 The RSDs of seven consecutive measurements in 1 μM FLE and VA solutions were 2.97% and 1.99%, respectively, indicating good reproducibility of the MIP / BPNS-Au / AgNPs / GCE. Five independent parallel determinations of 1 μM FLE and VA using the MIP / BPNS-Au / AgNPs / GCE solution showed RSDs of 4.89% and 2.98%, respectively, demonstrating good reproducibility of the electrode preparation. Furthermore, after 28 days, the RSDs of 1 μM FLE and VA were...pa Still maintained at 83.05% and 85.02% of the original value, respectively, which confirmed that the MIP / BPNS-Au / AgNP / GCE had good stability.

[0122] 5) Actual sample determination

[0123] The MIP / BPNS-Au / AgNP / GCE was used for the quantitative determination of FLE and VA in actual samples. Skimmed pure milk (250 mL / bag, Eli) was purchased from a local supermarket. The pure milk sample was diluted 100 times with 0.1 M PBS (pH = 5). Sewage was taken from the pool in front of the library of Hunan University of Technology. Different concentrations of FLE and VA standard solutions were added to the milk and sewage, respectively, and then the recovery rate was determined.

[0124] The detection results of FLE and VA in sewage and milk samples are shown in Tables 3 and 4, respectively.

[0125] Table 3

[0126]

[0127] Table 4

[0128]

[0129]

[0130] As can be seen from Tables 3 and 4, no FLE and VA residues were found in the sewage and milk samples. After adding FLE and VA standard solutions with known concentrations, the recovery rate was 91.17-107.97%. The added concentrations and the determined electrochemical performance test results of the sensor after incubation in sewage and milk samples with different concentrations of FLE (0.1-1 μM) and VA (0.1-1 μM) were linearly fitted, and the results are shown in Figure 11 As can be seen from the figure, the electrochemical performance change trend of MIP / BPNS-Au / AgNP / GCE after incubation in sewage and milk with different concentrations of FLE (0.1-1 μM) and VA (0.1-1 μM) was linear, and the slope was close to the standard curve, indicating that it could be well applied to the detection of actual samples.

[0131] The embodiments of the application are described in detail above with reference to the accompanying drawings, but the application is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the purpose of the application. In addition, the embodiments of the application and the features in the embodiments can be combined with each other without conflict.

Claims

1. A black phosphorus-gold / silver nanocomposite-based dual-template molecularly imprinted modified electrode, characterized in that: The modified electrode comprises an electrode substrate, an electrode sensitizing material layer and a double-template molecularly imprinted polymer film layer are sequentially modified on the electrode substrate, and an electrochemical probe is combined in the double-template molecularly imprinted polymer film layer, wherein the electrode sensitizing material layer comprises black phosphorus nanoparticle-gold / silver nanoparticle composite material, templates of the double-template molecularly imprinted polymer film layer are fluroxquinolone and vancomycin; the polymer film layer is at least one of a polypyrrole film layer, a polyaniline film layer, a polythiophene film layer, a polydopamine film layer and a poly-o-phenylenediamine film layer; and a preparation process of the black phosphorus nanoparticle-gold / silver nanoparticle composite material comprises the following steps: mixing chloroauric acid with black phosphorus, reacting under ultraviolet light irradiation, collecting a solid phase part I through solid-liquid separation, preparing the solid phase part I into a dispersion liquid I, adding a silver salt, dispersing the silver salt in the dispersion liquid I, reacting again under ultraviolet light irradiation, and collecting a solid phase part II through solid-liquid separation again, thereby obtaining the black phosphorus nanoparticle-gold / silver nanoparticle composite material.

2. The black phosphorus-gold / silver nanocomposite-based dual-template molecularly imprinted modified electrode according to claim 1, characterized in that: The electrochemical probe contains any one of methylene blue, ferrocene or [Fe(CN)6] 3- / 4- ; and / or, the electrode substrate is at least one of a glassy carbon electrode, a screen-printed carbon electrode, a gold electrode.

3. The preparation method of the black phosphorus-gold / silver nanocomposite-based dual-template molecularly imprinted modified electrode according to claim 1 or 2, characterized in that: The preparation method comprises the following steps: S1, preparing black phosphorus nanoparticle-gold / silver nanoparticle composite material: mixing chloroauric acid with black phosphorus, reacting under ultraviolet light irradiation, collecting a solid phase part I through solid-liquid separation, preparing the solid phase part I into a dispersion liquid I, adding a silver salt, dispersing the silver salt in the dispersion liquid I, reacting again under ultraviolet light irradiation, and collecting a solid phase part II through solid-liquid separation again, thereby obtaining the black phosphorus nanoparticle-gold / silver nanoparticle composite material; S2, preparing the black phosphorus nanoparticle-gold / silver nanoparticle composite material into a dispersion liquid II, and making the dispersion liquid form an electrode sensitizing material layer on an electrode substrate; S3, making functional monomers and template molecules form a double-template molecularly imprinted polymer film layer through electropolymerization on a surface of the electrode sensitizing material layer; S4, eluting and removing the templates, and making a surface of the double-template molecularly imprinted polymer film layer combine with an electrochemical probe in an electrochemical probe solution, thereby obtaining the modified electrode; wherein the template molecules are a mixture of fluroxquinolone and vancomycin.

4. The method of claim 3, wherein: The preparation method further comprises at least one of the following conditions: 1) in the step S1, a molar ratio of the chloroauric acid to the silver salt is 0.5-2:1, and a molar ratio of the black phosphorus to the chloroauric acid is 10:15-25; 2) in the step S3, a molar ratio of the pyrrole, fluroxquinolone and vancomycin is 0.25-4:1:1; 3) a number of electropolymerization circles is 5-15; 4) an electrochemical elution method is used when the templates are eluted; and a number of CV circles is 60 or more in a CV scanning process for eluting the double templates.

5. A dual-template molecularly imprinted sensor based on black phosphorus-gold / silver nanocomposite, characterized in that: The sensor comprises an electrode system and a supporting electrolyte solution, and the electrode system comprises the modified electrode according to claim 1 or 2.

6. A preparation method of a dual-template molecularly imprinted sensor based on black phosphorus-gold / silver nanocomposites, characterized in that: The preparation method comprises the following steps: S1, preparing black phosphorus nanoparticle-gold / silver nanoparticle composite material: mixing chloroauric acid with black phosphorus, reacting under ultraviolet light irradiation, collecting a solid phase part I through solid-liquid separation, preparing the solid phase part I into a dispersion liquid I, adding a silver salt, dispersing the silver salt in the dispersion liquid I, reacting again under ultraviolet light irradiation, and collecting a solid phase part II through solid-liquid separation again, thereby obtaining the black phosphorus nanoparticle-gold / silver nanoparticle composite material; S2, preparing the black phosphorus nanoparticle-gold / silver nanoparticle composite material into a dispersion liquid II, and making the dispersion liquid form an electrode sensitizing material layer on an electrode substrate; S3, making functional monomers and template molecules form a double-template molecularly imprinted polymer film layer through electropolymerization on a surface of the electrode sensitizing material layer; S4, eluting and removing the templates, and making a surface of the double-template molecularly imprinted polymer film layer combine with an electrochemical probe in an electrochemical probe solution, thereby obtaining the modified electrode; wherein the template molecules are a mixture of fluroxquinolone and vancomycin. The preparation method further comprises at least one of the following conditions: 1) in the step S1, a molar ratio of the chloroauric acid to the silver salt is 0.5-2:1, and a molar ratio of the black phosphorus to the chloroauric acid is 10:15-25; 2) in the step S3, a molar ratio of the pyrrole, fluroxquinolone and vancomycin is 0.25-4:1:1; 3) a number of electropolymerization circles is 5-15; 4) an electrochemical elution method is used when the templates are eluted; and a number of CV circles is 60 or more in a CV scanning process for eluting the double templates. The sensor comprises an electrode system and a supporting electrolyte solution, and the electrode system comprises the modified electrode according to claim 1 or 2.

7. The method of claim 6, wherein: The preparation method further comprises the steps of taking an auxiliary electrode, a reference electrode and a supporting electrolyte solution to cooperate to form the sensor, wherein the supporting electrolyte comprises a phosphate buffer salt, the concentration of the phosphate buffer salt in the supporting electrolyte solution is 0.08-0.12 mol / L, and the pH of the supporting electrolyte solution is 4-7.

8. Use of the black phosphorus-gold / silver nanocomposite-based dual-template molecularly imprinted sensor of claim 5 in detecting FLE and / or VA.

9. A method for detecting antibiotics by using the dual-template molecularly imprinted sensor based on black phosphorus-gold / silver nanocomposites according to claim 5, characterized in that: It comprises the following steps: incubating the modified electrode in a solution containing a supporting electrolyte and an antibiotic, using a double signal strategy, taking [Fe(CN)6] 3- / 4- As an electrochemical probe, detecting the antibiotic by voltammetry; wherein the antibiotic comprises fleroxacin and / or vancomycin, and the voltammetry is one of linear sweep voltammetry, differential pulse voltammetry and square wave pulse voltammetry.

10. The method of claim 9, wherein: The incubation time is 6-10 min.

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