An electrochemical molecular imprinting sensor and its preparation method and application

Abstract

The present invention relates to an electrochemical molecular imprinting sensor, its preparation method, and its application for highly selective identification of perfluorooctane sulfonic acid. The electrochemical molecular imprinting sensor comprises a base electrode and, sequentially applied to the surface of the base electrode, gold nanoparticles with a particle size range of 35-40 nm; a probe with multiple fluorophilic interactions; and a molecular imprinting membrane whose functional monomer is o-phenylenediamine. The electrochemical molecular imprinting sensor provided by the present invention exhibits high selectivity, fast response, and excellent sensitivity.

Description

Technical Field

[0001] The present invention relates to the technical field of pollutant detection, and in particular to an electrochemical molecular imprinting sensor and a preparation method and application thereof. Background Art

[0002] Perfluorooctane sulfonate (PFOS) has become a significant emerging pollutant for water monitoring due to its bioaccumulation, neurotoxicity, reproductive and developmental toxicity, and endocrine disrupting properties. Currently, the detection of PFOS in water relies primarily on liquid chromatography-mass spectrometry. Although these methods are highly sensitive, they rely on expensive equipment and require lengthy sample preparation, making them inadequate for on-site detection of PFOS in environmental samples. Summary of the Invention

[0003] In view of the above analysis, embodiments of the present invention aim to provide an electrochemical molecular imprinting sensor and a preparation method and application thereof, so as to solve at least one of the above problems.

[0004] In one aspect, the present invention provides an electrochemical molecular imprinting sensor, comprising a base electrode and:

[0005] Gold nanoparticles, with a particle size range of 35-40 nm;

[0006] Probes with multiple fluorophilic interactions;

[0007] Molecularly imprinted membrane, whose functional monomer is o-phenylenediamine.

[0008] Furthermore, the base electrode is a glassy carbon electrode, a gold electrode or a screen-printed electrode.

[0009] Furthermore, the probe having multiple fluorine-affinity effects is 1H,1H,2H,2H-perfluorodecylthiol.

[0010] In another aspect, the present invention provides a method for preparing an electrochemical molecular imprinting sensor, which can at least be used to prepare the above-mentioned electrochemical molecular imprinting sensor. The preparation method comprises the following steps:

[0011] S100: Provide basic electrodes;

[0012] S200: modifying the base electrode with gold nanoparticles to obtain a gold nanoparticle / base electrode;

[0013] S300: modifying the gold nanoparticle / basic electrode with the F17 probe to obtain the F17 / gold nanoparticle / basic electrode;

[0014] S400: immersing the F17 / gold nanoparticle / base electrode in a PFOS solution, and utilizing the FF bond interaction between F17 and PFOS to obtain a PFOS / F17 / gold nanoparticle / base electrode;

[0015] S500: PFOS / F17 / gold nanoparticles / base electrode are placed in an o-phenylenediamine solution, and o-phenylenediamine is electrochemically polymerized on the surface of PFOS / F17 / gold nanoparticles / base electrode using cyclic voltammetry. PFOS is then eluted in a methanol-water mixed solution, and an electrochemical molecular imprinting sensor is finally obtained.

[0016] Furthermore, the base electrode needs to be polished first, and then placed in ethanol and ultrapure water in sequence for step-by-step ultrasonic treatment for 5 to 10 minutes.

[0017] Furthermore, in step S200, the base electrode is immersed in a 0.5 mM HAuCl4 solution, and gold nanoparticles / base electrode are prepared by chronoamperometry and cyclic voltammetry;

[0018] The test conditions of the chronoamperometry were as follows: initial potential of 0.8 V, pulse width of 15 s;

[0019] The test conditions of cyclic voltammetry were as follows: potential range of -0.4 V to 0.3 V, scan rate of 50 mV / s, and number of cycles of 50.

[0020] Furthermore, in step S300, the gold nanoparticles / basic electrode is immersed in an F17 probe solution and incubated at room temperature to obtain an F17 / gold nanoparticles / basic electrode.

[0021] Furthermore, in step S400, the concentration of the PFOS solution is 1 mM to 5 mM, and the F17 / gold nanoparticles / base electrode is immersed in the PFOS solution and incubated for 20 to 180 min.

[0022] Furthermore, in step S500, the methanol-water mixture is a mixture of methanol and water in a volume ratio of 0:1 to 7:1.

[0023] The present invention also provides an application of an electrochemical molecular imprinting sensor. The electrochemical molecular imprinting sensor prepared based on the above preparation method can be used for the detection of perfluorooctane sulfonic acid.

[0024] Compared with the prior art, the present invention can achieve at least one of the beneficial effects. Based on the basic electrode, the present invention utilizes the multiple fluorine-affinity effects of perfluorinated substances and combines molecular imprinting recognition technology to prepare a highly selective electrochemical molecular imprinting sensor capable of detecting perfluorooctane sulfonic acid in water environment.

[0025] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of the present invention will be described in the following description, and some advantages will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0027] Figure 1 DPV graphs of AuNPs / GCE, F17 / AuNPs / GCE, PFOS / F17 / AuNPs / GCE, and o-PDMIP / PFOS / F17 / AuNPs / GCE (before and after PFOS elution) in a specific embodiment;

[0028] Figure 2 is the FESEM of o-PD MIP / F17 / AuNPs / GCE in a specific embodiment;

[0029] Figure 3 The DPV curve (left) and the established standard curve (right) in the concentration range of 0-1 mM PFOS in a specific embodiment are shown;

[0030] Figure 4 3 is a comparison chart of the recognition performance of the electrochemical molecular imprinting sensor for PFOS and perfluorinated analogues (PFOA, PFNA, PFHPA and PFDA) in a specific embodiment. DETAILED DESCRIPTION

[0031] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0032] In the description of the embodiments of the present invention, it should be noted that, unless otherwise specified or limited, the term "connected" should be understood in a broad sense. For example, it can mean a fixed connection, a detachable connection, or an integral connection. It can be a mechanical connection, an electrical connection, a direct connection, or an indirect connection through an intermediate medium. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0033] The terms "top," "bottom," "above," "below," and "on" used throughout the description refer to relative positions of components of a device, such as the relative positions of top and bottom substrates within a device. It will be understood that devices are multifunctional regardless of their orientation in space.

[0034] The working surface of the present invention can be a plane or a curved surface, can be inclined, or can be horizontal. For the convenience of description, the embodiment of the present invention is placed on a horizontal surface and used on the horizontal surface, and "high and low" and "up and down" are defined in this way.

[0035] A specific embodiment of the present invention discloses an electrochemical molecular imprinting sensor, comprising a base electrode and:

[0036] Gold nanoparticles (AuNPs), with a particle size range of 35–40 nm;

[0037] Probes with multiple fluorophilic interactions;

[0038] Molecularly imprinted polymer (MIP), whose functional monomer is o-phenylenediamine (o-PD).

[0039] The electrochemical molecular imprinting sensor (hereinafter referred to as the sensor) of the present invention can be used to quickly detect PFOS in environmental samples, and has the characteristics of high selectivity, high sensitivity and strong stability.

[0040] The base electrode is a glassy carbon electrode, a gold electrode or a screen-printed electrode, preferably a glassy carbon electrode (GCE) because of its advantages of good conductivity, high chemical stability, wide application range and easy processing.

[0041] By modifying the glassy carbon electrode with gold nanoparticles, the active area of ​​the electrode surface was increased, which promoted the Fe 2+ Fe 3+ The conversion process can improve the electrochemical response signal of the prepared sensor to potassium ferrocyanide.

[0042] The probe with multiple fluorine-affinity is 1H,1H,2H,2H-perfluorodecylthiol (chemical formula: C 10 H5F 17 F17 has multiple fluorine-loving properties and can be used for the selective recognition of PFOS. The FF bond between F17 and PFOS can prevent the adhesion of other organic matter and ions in water.

[0043] The molecular imprinting membrane is electrochemically polymerized on the surface of the F17 / gold nanoparticles / base electrode using cyclic voltammetry in an o-phenylenediamine solution, and then perfluorooctane sulfonic acid is eluted in a methanol / water mixed solution to finally obtain the electrochemical molecular imprinting sensor of perfluorooctane sulfonic acid.

[0044] The present invention also provides a method for preparing the electrochemical molecular imprinting sensor, comprising the following steps:

[0045] S100: Provide basic electrodes;

[0046] S200: modifying the base electrode with gold nanoparticles to obtain a gold nanoparticle / base electrode;

[0047] S300: modifying the gold nanoparticle / basic electrode with the F17 probe to obtain the F17 / gold nanoparticle / basic electrode;

[0048] S400: immersing the F17 / gold nanoparticle / base electrode in a PFOS solution, and utilizing the FF bond interaction between F17 and PFOS to obtain a PFOS / F17 / gold nanoparticle / base electrode;

[0049] S500: PFOS / F17 / gold nanoparticles / base electrode are placed in an o-phenylenediamine solution, and o-phenylenediamine is electrochemically polymerized on the surface of PFOS / F17 / gold nanoparticles / base electrode using cyclic voltammetry. PFOS is then eluted in a methanol-water mixed solution, and an electrochemical molecular imprinting sensor is finally obtained.

[0050] In step S100, the base electrode needs to be polished (for example, the glassy carbon electrode is polished with 0.03 μm aluminum oxide powder on the skin), and then placed in ethanol and ultrapure water in sequence for 5 to 10 minutes of step-by-step ultrasonic treatment.

[0051] In step S200, the base electrode was immersed in a 0.5 mM HAuCl₄ solution, and the gold nanoparticle / base electrode was prepared using chronoamperometry and cyclic voltammetry. The chronoamperometry test conditions were: an initial potential of 0.8 V and a pulse width of 15 s; the cyclic voltammetry test conditions were: a potential range of -0.4 V to 0.3 V, a scan rate of 50 mV / s, and 50 cycles.

[0052] In step S300, the gold nanoparticle / base electrode is immersed in an F17 probe solution and incubated at room temperature (20-30°C) to form an F17 / gold nanoparticle / base electrode. The F17 is primarily bonded to the surface of the gold nanoparticles through Au-S bonds. The F17 probe solution has a concentration of 80-110 mM (preferably 100 mM) and is incubated at room temperature for 20-120 minutes. Exemplary incubation times include 20, 40, 60, 90, and 120 minutes. The F17 probe solution is prepared using ultrapure water.

[0053] In step S400, the concentration of the PFOS solution is 1 mM to 5 mM, and the F17 / gold nanoparticle / base electrode is immersed in the PFOS solution and incubated for 20 to 180 minutes. Exemplary incubation times are 20, 40, 60, 120, and 180 minutes. PFOS primarily interacts with the F17 probe through the FF bond.

[0054] In step S500, the methanol-water mixture is prepared by mixing methanol and water at a volume ratio of 0:1 to 7:1 (illustratively, 0:1, 3:1, 7:1, 1:0, etc.; preferably 5:1). The methanol-water mixture can elute PFOS molecules embedded in the imprinted membrane.

[0055] After elution, the sensor was air-dried and stored, preferably under nitrogen atmosphere, in a refrigerator at 4°C.

[0056] The electrochemical molecular imprinting sensor of the present invention can be used for the detection of perfluorooctane sulfonic acid (PFOS), at least for detecting whether an environmental sample contains PFOS, and further for detecting the content of PFOS in the environmental sample by differential pulse voltammetry.

[0057] During field use, the prepared o-PD MIP / F17 / AuNPs / GCE electrode (prepared in the laboratory and brought to the site) was first tested for a blank background value in 5 mL of 5 mM iron / potassium ferroferrocyanide solution to obtain a current value (I0). Subsequently, the electrode was immersed in the water sample to be tested for 60 minutes, and a subsequent differential pulsed voltammetry (DPV) test was performed using the same process. After the test, the PFOS concentration in the water was calculated based on the calibration curve.

[0058] The DPV test was performed in 5 mL of 5 mM iron / potassium ferrocyanide solution (Fe 3+ with Fe 2+The test was carried out in a three-electrode system, in which the prepared electrode was the working electrode, the platinum wire was the counter electrode, and the silver / silver chloride was the reference electrode. The potential range of the parameters was -0.1~0.6 V (vs Ag / AgCl), and the scanning speed was 50 mV / s.

[0059] By constructing a PFOS calibration curve within a standard concentration range, fluorooctane sulfonic acid (FBS) in environmental samples can be quantified. For example, a standard curve covering a PFOS concentration range of 0–1 mM can be constructed to measure PFOS concentrations within this range.

[0060] The electrochemical molecular imprinting sensor of the present invention uses iron / potassium ferrocyanide as an external standard probe. When PFOS exists, the Fe in the potassium ferrocyanide solution near the electrode interface 2+ Fe 3+ The conversion of PFOS is suppressed, resulting in a lower signal response. When PFOS is eluted, a higher current value is generated. Differential pulse voltammetry is used to measure the sensor before and after elution, and the signal change between the probes before and after elution is obtained, thereby quantitatively analyzing the PFOS concentration in the water sample.

[0061] The electrochemical molecular imprinting sensor of the present invention can be used to detect PFOS in water environment and has the characteristics of high selectivity, high sensitivity and strong stability.

[0062] [Example] An electrochemical molecular imprinting sensor is provided, and the preparation method thereof comprises the following steps:

[0063] S100: Provide a glassy carbon electrode (GCE), polish it, and then ultrasonicate it in ethanol and ultrapure water for 5 minutes in sequence;

[0064] S200: The glassy carbon electrode was immersed in a 0.5 mM HAuCl4 solution, and gold nanoparticles / glassy carbon electrode (denoted as AuNPs / GCE) was prepared by chronoamperometry and cyclic voltammetry.

[0065] S300: AuNPs / GCE was immersed in 100 mM F17 solution and incubated at room temperature for 90 min to obtain F17 / gold nanoparticles / glassy carbon electrode (denoted as F17 / AuNPs / GCE);

[0066] S400: Immerse the above-mentioned F17 / AuNPs / GCE in a 2 mM perfluorooctanesulfonic acid solution and incubate at room temperature for 60 min to obtain a PFOS / F17 / gold nanoparticle / glassy carbon electrode (denoted as PFOS / F17 / AuNPs / GCE);

[0067] S500: PFOS / F17 / AuNPs / GCE was placed in 5 mL of a 10 mM o-phenylenediamine solution. O-phenylenediamine was electrochemically polymerized on the surface of the PFOS / F17 / gold nanoparticles / glassy carbon electrode using cyclic voltammetry. Specifically, cyclic voltammetry (CV) was performed over a potential range of 0–1 V at a scan rate of 50 mV / s for eight cycles to obtain an o-PD MIP / PFOS / F17 / gold nanoparticles / glassy carbon electrode (denoted as o-PD MIP / PFOS / F17 / AuNPs / GCE).

[0068] The o-PD MIP / PFOS / F17 / AuNPs / GCE was placed in a mixed solution of methanol and water with a volume ratio of 5:1 to remove PFOS, and finally an electrochemical molecular imprinting sensor (denoted as o-PD MIP / F17 / AuNPs / GCE) was obtained.

[0069] In the presence of 5 mM [Fe(CN)6] 3- / 4- Differential pulse voltammetry was used in solution to characterize the electrochemical behaviors of o-PD MIP / PFOS / F17 / AuNPs / GCE electrode before and after PFOS removal, AuNPs / GCE, F17 / AuNPs / GCE, and PFOS / F17 / AuNPs / GCE. The characterization results are shown in Figure 2. Figure 1 As shown in the DPV diagram, it can be seen that after F17 modification, its current value is significantly reduced. After further assembly of PFOS, the current value is further reduced. Subsequently, after polymerization of o-phenylenediamine, the current value of DPV also decreases. After PFOS is eluted, the current value increases significantly, indicating that PFOS is successfully removed from the molecular imprinting membrane.

[0070] Figure 2 This is the field emission scanning electron microscopy (FESEM) of o-PD MIP / F17 / AuNPs / GCE. It can be seen from the figure that the electrode surface has a film-like structure, indicating the successful preparation of the sensor interface.

[0071] The o-PD MIP / F17K / AuNPs / GCE was used for PFOS detection in water environments by incubating in real water samples. The DPV curves and the established standard curve were performed in the same process within the concentration range of 0-1 mM PFOS. The potential range of the DPV test was -0.1 V to 0.6 V (vs Ag / AgCl) with a scan rate of 50 mV / s. The experimental results are shown in Figure 2. Figure 3 As shown in the figure, it can be seen that the electrochemical molecular imprinting sensor of the present invention has the characteristics of high sensitive response (R 2 =0.9903).

[0072] The prepared sensor was used to study the selectivity of the sensor of the present invention with the same concentration of perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), tridecafluoroheptanoic acid (PFHPA), and nonadecafluorodecanoic acid (PFDA). Figure 4 As shown in the figure, since PFOS was selected as the template molecule for polymerization during the preparation of o-PDMIP / F17 / AuNPs / GCE, the prepared sensor had no obvious recognition ability for other perfluorinated analogues, which also shows that the sensor prepared by the present invention has the characteristics of high selectivity.

[0073] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for preparing an electrochemical molecular imprinting sensor, characterized in that: The preparation method comprises the following steps: S100: Provide basic electrodes; S200: modifying the base electrode with gold nanoparticles to obtain a gold nanoparticle / base electrode; S300: modifying the gold nanoparticle / base electrode with an F17 probe to obtain an F17 / gold nanoparticle / base electrode, wherein the F17 probe is 1H,1H,2H,2H-perfluorodecylthiol; S400: immersing the F17 / gold nanoparticle / base electrode in a PFOS solution, and utilizing the FF bond interaction between F17 and PFOS to obtain a PFOS / F17 / gold nanoparticle / base electrode; S500: PFOS / F17 / gold nanoparticles / base electrode are placed in an o-phenylenediamine solution, and o-phenylenediamine is electrochemically polymerized on the surface of PFOS / F17 / gold nanoparticles / base electrode using cyclic voltammetry. PFOS is then eluted in a methanol-water mixed solution, and an electrochemical molecular imprinting sensor is finally obtained.

2. The method for preparing an electrochemical molecular imprinting sensor according to claim 1, wherein: The base electrode needs to be polished first, and then placed in ethanol and ultrapure water in sequence for step-by-step ultrasonic treatment for 5 to 10 minutes.

3. The method for preparing an electrochemical molecular imprinting sensor according to claim 1, wherein: In step S200, the base electrode is immersed in a 0.5 mM HAuCl4 solution, and gold nanoparticles / base electrode are prepared by chronoamperometry and cyclic voltammetry; The test conditions of the chronoamperometry were as follows: initial potential of 0.8 V, pulse width of 15 s; The test conditions of cyclic voltammetry were as follows: potential range of -0.4 V to 0.3 V, scan rate of 50 mV / s, and number of cycles of 50.

4. The method for preparing an electrochemical molecular imprinting sensor according to claim 1, wherein: In step S300, the gold nanoparticle / basic electrode is immersed in an F17 probe solution and incubated at room temperature to obtain an F17 / gold nanoparticle / basic electrode.

5. The method for preparing an electrochemical molecular imprinting sensor according to claim 4, characterized in that: In step S400 , the concentration of the PFOS solution is 1 mM to 5 mM, and the F17 / gold nanoparticles / base electrode is immersed in the PFOS solution and incubated for 20 to 180 minutes.

6. The method for preparing an electrochemical molecular imprinting sensor according to claim 1, wherein: In step S500 , the methanol-water mixture is a mixture of methanol and water in a volume ratio of 3:1 to 7:

1.

7. An application of an electrochemical molecular imprinting sensor, characterized in that: The electrochemical molecular imprinting sensor prepared according to the preparation method according to any one of claims 1 to 6 can be used for the detection of perfluorooctane sulfonic acid.

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