A molecular imprinting sensor based on phenylalanine-prochloraz and its preparation method

Abstract

The invention discloses a molecular imprinting sensor based on phenylalanine-prochloraz and a preparation method thereof, and relates to the technical field of molecular imprinting sensors. The preparation method comprises the following steps: S1. soaking a bare gold electrode in dilute nitric acid, rinsing the electrode, and then ultrasonically placing the electrode in anhydrous ethanol; polishing the surface of suede with aluminum oxide polishing powder; using a mixed solution of K4[Fe(CN)6] / K3[Fe(CN)6] and KCl as a probe molecule, performing cyclic voltammetry until the potential difference is no more than 120 mV, and obtaining a cleaned gold electrode; S2. immersing the cleaned gold electrode in a phenylalanine-polylysine complex framework solution for adsorption, and then placing the electrode in a prochloraz solution for hydrogen bonding, and electropolymerizing the electrode using o-phenylenediamine to obtain a gold electrode having a molecular imprinting polymer; and S3. eluting the prochloraz molecules from the gold electrode having the molecular imprinting polymer with a mixed solution of acetic acid and water, and obtaining the molecular imprinting sensor based on phenylalanine-prochloraz.

Description

Technical Field

[0001] The present invention relates to the technical field of molecular imprinted sensors, and in particular to a molecular imprinted sensor based on phenylalanine-prochloraz and a preparation method thereof. Background Art

[0002] Pesticide residue refers to the pesticides sprayed during the cultivation process, as well as their toxic metabolites, degradation products, and reaction impurities remaining on agricultural products. Pesticides are difficult to degrade, prone to residue, and highly toxic. While they prevent and control crop diseases, they also damage the environment, enter the food chain, and endanger human and animal health.

[0003] Prochloraz is a highly effective, low-toxic, broad-spectrum fungicide synthesized by the British company Boots. It plays an important role in crop production, demonstrating significant efficacy against a wide range of crop diseases caused by ascomycetes and deuteromycetes. It can also be mixed with most fungicides, insecticides, and herbicides, achieving good control results. Prochloraz has a wide range of uses, with residues often found in fruits, vegetables, and grains. It poses minimal harm to humans, generally causing mild irritation to the skin and eyes. Oral poisoning is low in toxicity and can be treated with gastric lavage and vomiting, with few reports of poisoning. Within the pesticide residue limit, prochloraz poses low risks to mutagenicity, teratogenicity, and carcinogenesis. However, prochloraz poses a high risk to aquatic organisms, and improper use can cause serious damage to the ecological environment. China's GB 2763-2016 stipulates a maximum residue limit of 0.1 to 10 mg / kg for prochloraz on crops. -1 Currently, the main methods for detecting prochloraz are gas chromatography, high-performance liquid chromatography, mass spectrometry, liquid chromatography-tandem mass spectrometry, and near-infrared spectroscopy. However, these methods have lengthy pretreatment steps, expensive experimental instruments, and long experimental times, making real-time analysis impossible. These methods fail to address the need for efficient and convenient detection of prochloraz.

[0004] Molecular imprinting sensors offer advantages such as high selectivity, low detection limits, and excellent stability, and have demonstrated outstanding performance in pesticide residue detection. The principle of molecular imprinting technology is to combine functional monomers with target molecules to form a complex. Cross-linking further enhances the stability of the complex. Elution of the template molecule yields highly selective imprinted pores, which, when combined with the target molecule, can identify, detect, and separate the target. However, conventionally prepared molecular imprinting sensors suffer from shortcomings such as uneven pore distribution and easy collapse, difficulty eluting the template molecule, prolonged binding to the target molecule, and poor selectivity for the target molecule.

[0005] At present, there is no molecular imprinting sensor based on phenylalanine-prochloraz that is convenient, rapid, stable, and has good selectivity for prochloraz. Summary of the Invention

[0006] To address the shortcomings of the prior art, the present invention provides a phenylalanine-prochloraz-based molecular imprinting sensor and its preparation method. The preparation method provided by the present invention first synthesizes a phenylalanine-polylysine complex framework, which is fixed to a gold electrode. The complex framework interacts with prochloraz to enrich and immobilize prochloraz, forming a prochloraz-amino acid composite framework complex. A crosslinker is then polymerized and encapsulated in the complex by electropolymerization. After prochloraz is eluted separately, molecular imprinting pores are formed that match each other in spatial conformation, structure, size, and recognition sites, thereby obtaining a phenylalanine-prochloraz-based molecular imprinting sensor that can specifically recognize prochloraz molecules. The phenylalanine-prochloraz-based molecular imprinting sensor prepared by the preparation method provided by the present invention can quickly, efficiently and sensitively identify prochloraz molecules, and has strong anti-interference ability. Compared with traditional molecular imprinting sensors, the molecular imprinting sensor prepared using the phenylalanine-polylysine composite framework of the present invention has a significantly improved selectivity detection limit, a wide range of applications, strong practicality, is not limited by material structure and functional group type, and can be used for the detection of pesticide residue molecules.

[0007] One object of the present invention is to provide a method for preparing a molecular imprinting sensor based on phenylalanine-prochloraz. The preparation method comprises the following steps:

[0008] S1. Soak a bare gold electrode in dilute nitric acid, rinse it, and then ultrasonicate it in anhydrous ethanol. Polish the suede surface with alumina polishing powder. Cyclic voltammetry is performed using a mixed solution of K₄[Fe(CN)₆] / K₃[Fe(CN)₆] and KCl as a probe molecule until the potential difference is no greater than 120 mV. This yields a cleaned gold electrode.

[0009] S2. Immersing the washed gold electrode in a phenylalanine-polylysine complex framework solution for adsorption to obtain a gold electrode assembled with a phenylalanine-polylysine complex framework, then placing it in a prochloraz solution for hydrogen bonding to obtain a gold electrode assembled with prochloraz molecules, and electropolymerizing it with o-phenylenediamine to obtain a gold electrode with a molecularly imprinted polymer;

[0010] S3. The gold electrode with the molecularly imprinted polymer is used to elute the prochloraz molecules with a mixed solution of acetic acid and water to obtain the phenylalanine-prochloraz-based molecular imprinting sensor.

[0011] Preferably, in step S1, the concentration of the dilute nitric acid is 1 mol / L, the soaking time is 5 min, and the ultrasonication time is 3 min.

[0012] Preferably, in step S1, the size of the aluminum oxide polishing powder is 0.03 μm.

[0013] Preferably, in step S1, the concentrations of K4[Fe(CN)6] / K3[Fe(CN)6] and KCl in the mixed solution of K4[Fe(CN)6] / K3[Fe(CN)6] and KCl are 5.0×10 -3 mol / L, 0.1mol / L.

[0014] Preferably, in step S2, the concentration of the phenylalanine-polylysine complex framework solution is 1.0×10 - 4 mol / L, and the adsorption time is 60 min.

[0015] In step S2, the concentration of the prochloraz solution is 1.0×10 -4 mol / L, and the hydrogen bond binding time is 30 min.

[0016] In step S2, the concentration of o-phenylenediamine is 5.0×10 -4 moL / L; the conditions for electropolymerization: the scanning voltage range is -0.2 to 0.6V, and the film is polymerized ten times at a rate of 0.05V / s.

[0017] In step S3, the volume ratio of acetic acid to water in the mixed solution of acetic acid and water is 4:1, and the elution time is 6 minutes.

[0018] The preparation method of the phenylalanine-polylysine complex framework solution comprises the following steps:

[0019] S101. To a 50.0 mL three-necked round-bottom flask, 16.5189 g of DL-β-phenylalanine was added. A magnetic stirrer was turned on and 25.00 mL of thionyl chloride was slowly added dropwise. The mixture was allowed to react in a fume hood for 2 h. The excess thionyl chloride was removed by rotary evaporation under reduced pressure to obtain a solid powder of phenylalanine chloride.

[0020] S102. Weigh 0.0385 g of polylysine into a beaker, add 30 mL of 0.2 mol / L NaOH solution, add 0.0165 g of phenylalanine chloride, stir and dissolve with a magnetic stirrer, transfer to a 100 mL volumetric flask, and dilute to volume with secondary water to obtain the phenylalanine-polylysine complex framework solution, which is then refrigerated.

[0021] Another object of the present invention is to protect the phenylalanine-prochloraz-based molecular imprinting sensor prepared by the above-mentioned preparation method.

[0022] The beneficial effects of the present invention are embodied in:

[0023] (1) The preparation method provided by the present invention first synthesizes a phenylalanine-polylysine complex framework, fixes it on a gold electrode, utilizes the interaction between the complex framework and prochloraz to enrich and fix prochloraz, and forms a prochloraz-amino acid complex framework complex. Then, a cross-linking agent is polymerized and wrapped with the complex by electropolymerization. After the prochloraz is eluted separately, molecular imprinting pores are formed that match each other in spatial conformation, structure, size, and recognition sites, thereby obtaining a phenylalanine-prochloraz-based molecular imprinting sensor that can specifically recognize the prochloraz molecule.

[0024] (2) The logarithm of the electrical signal intensity and the concentration of prochloraz in the molecular imprinting sensor based on phenylalanine-prochloraz provided by the present invention is within 1.0×10 -15 mol / L to 1.0×10 -12 There is a good linear relationship between the two, and the detection limit is DL = 9.2231 × 10 -16 mol / L, the linear equation is Δi(μA)=189.19+12.4673lgC(mol / L), and the correlation coefficient r=0.9997. Applied to the detection of prochloraz samples, the recoveries ranged from 97.0% to 104.0%, demonstrating practical applicability.

[0025] (3) The molecular imprinting sensor based on phenylalanine-myclobutanil prepared by the preparation method provided by the present invention can quickly, efficiently and sensitively identify myclobutanil molecules, and has strong anti-interference ability. Compared with traditional molecular imprinting sensors, the molecular imprinting sensor prepared using the phenylalanine-polylysine composite framework of the present invention has a significantly improved selective detection limit, a wide range of applications, strong practicality, is not limited by the material structure and functional group type, and can be used for the detection of pesticide residue molecules. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly describes the drawings required for the specific embodiments or the description of the prior art. Similar elements or parts are generally identified by similar reference numerals throughout the drawings. Elements or parts in the drawings are not necessarily drawn to scale.

[0027] Figure 1 The voltammetric response diagram of the molecular imprinting sensor based on phenylalanine-prochloraz provided in the embodiment;

[0028] Figure 2 is the voltammetric response diagram of the non-molecular imprinting sensor prepared in comparative example;

[0029] Figure 3 This is an impedance response diagram of the molecular imprinting sensor based on phenylalanine-prochloraz prepared in Example;

[0030] Figure 4 The infrared spectra of the framework of phenylalanine, polylysine and phenylalanine-polylysine complex;

[0031] Figure 5 The infrared spectra of phenylalanine-polylysine-prochloraz and prochloraz;

[0032] Figure 6 A graph showing the current response signal of the molecular imprinting sensor based on phenylalanine-prochloraz provided in the embodiment when exposed to prochloraz solutions of different concentrations;

[0033] Figure 7 A diagram showing the anti-interference capability of the molecular imprinting sensor based on phenylalanine-prochloraz provided in the embodiment;

[0034] Attachment Figure 1 a-bare gold electrode, b-gold electrode after assembling phenylalanine-polylysine complex framework, c-gold electrode after assembling prochloraz molecules, d-gold electrode with molecularly imprinted polymer, e-molecularly imprinted sensor based on phenylalanine-prochloraz, f-electrode of molecularly imprinted sensor based on phenylalanine-prochloraz placed at 1.0×10 - 9 mol / L prochloraz solution for re-adsorption;

[0035] Attachment Figure 2 a-bare gold electrode, b-gold electrode after assembling phenylalanine-polylysine complex framework, c-gold electrode after poly film, d-non-molecularly imprinted sensor, e-non-molecularly imprinted sensor placed in 1.0×10-9mol / L prochloraz solution for re-adsorption for 30min;

[0036] Attachment Figure 3 a-bare gold electrode, b-gold electrode after assembling phenylalanine-polylysine complex framework, c-gold electrode after assembling prochloraz molecules, d-gold electrode with molecularly imprinted polymer, e-molecularly imprinted sensor based on phenylalanine-prochloraz, f-electrode of molecularly imprinted sensor based on phenylalanine-prochloraz placed at 1.0×10 - 9 mol / L prochloraz solution for re-adsorption;

[0037] Attachment Figure 4 Middle, a-phenylalanine, b-polylysine, c-phenylalanine-polylysine complex framework;

[0038] Attachment Figure 5 middle, d -phenylalanine-polylysine-prochlorazine, e -prochlorazine;

[0039] Attachment Figure 6The concentration of a-prochloraz was 1.0×10 -15 mol / L, the concentration of b-prochloraz was 5.0×10 -15 mol / L, the concentration of c-prochloraz was 7.0×10 -15 mol / L, the concentration of d-prochloraz was 1.0×10 -14 mol / L, the concentration of e-prochloraz was 5.0×10 -14 mol / L, f-prochloraz concentration was 7.0×10 -14 mol / L, g-prochloraz concentration was 1.0×10 -13 mol / L, the concentration of h-prochloraz was 5.0×10 -13 mol / L. DETAILED DESCRIPTION

[0040] The following embodiments of the technical solution of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention and are therefore only examples and are not intended to limit the scope of protection of the present invention.

[0041] It should be noted that, unless otherwise specified, the technical or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0042] Example

[0043] This embodiment provides a method for preparing a molecular imprinting sensor based on phenylalanine-prochloraz, and the steps are as follows:

[0044] S1. Soak a bare gold electrode in dilute nitric acid, rinse it, and then ultrasonicate it in anhydrous ethanol. Polish the suede surface with alumina polishing powder. Cyclic voltammetry is performed using a mixed solution of K₄[Fe(CN)₆] / K₃[Fe(CN)₆] and KCl as a probe molecule until the potential difference is no greater than 120 mV. This yields a cleaned gold electrode.

[0045] S2. Immersing the washed gold electrode in a phenylalanine-polylysine complex framework solution for adsorption to obtain a gold electrode assembled with a phenylalanine-polylysine complex framework, then placing it in a prochloraz solution for hydrogen bonding to obtain a gold electrode assembled with prochloraz molecules, and electropolymerizing it with o-phenylenediamine to obtain a gold electrode with a molecularly imprinted polymer;

[0046] S3. The gold electrode with molecularly imprinted polymer was used to elute the prochloraz molecules with a mixed solution of acetic acid and water to obtain a molecular imprinting sensor based on phenylalanine-prochloraz.

[0047] Wherein, in step S1, the concentration of dilute nitric acid is 1 mol / L, the soaking time is 5 min, and the ultrasonication time is 3 min.

[0048] In step S1 , the size of the aluminum oxide polishing powder is 0.03 μm.

[0049] In step S1, the concentrations of K4[Fe(CN)6] / K3[Fe(CN)6] and KCl in the mixed solution of K4[Fe(CN)6] / K3[Fe(CN)6] and KCl are 5.0×10 -3 mol / L, 0.1mol / L.

[0050] In step S2, the concentration of the phenylalanine-polylysine complex framework solution was 1.0×10 -4 mol / L, and the adsorption time was 60 min.

[0051] In step S2, the concentration of the prochloraz solution is 1.0×10 -4 mol / L, and the hydrogen bonding time is 30 min.

[0052] In step S2, the concentration of o-phenylenediamine is 5.0×10 -4 moL / L; conditions for electropolymerization: scanning voltage range is -0.2~0.6V, and the film is polymerized ten times at a rate of 0.05V / s.

[0053] In step S3, the volume ratio of acetic acid to water in the mixed solution of acetic acid and water is 4:1, and the elution time is 6 minutes.

[0054] The preparation method of the phenylalanine-polylysine complex framework solution comprises the following steps:

[0055] S101. To a 50.0 mL three-necked round-bottom flask, 16.5189 g of DL-β-phenylalanine was added. A magnetic stirrer was turned on and 25.00 mL of thionyl chloride was slowly added dropwise. The mixture was allowed to react in a fume hood for 2 h. The excess thionyl chloride was removed by rotary evaporation under reduced pressure to obtain a solid powder of phenylalanine chloride.

[0056] S102. Weigh 0.0385 g of polylysine into a beaker, add 30 mL of 0.2 mol / L NaOH solution, add 0.0165 g of phenylalanine chloride, stir and dissolve with a magnetic stirrer, transfer to a 100 mL volumetric flask, and dilute to volume with secondary water to obtain the phenylalanine-polylysine complex framework solution, which is then refrigerated.

[0057] Comparative Example

[0058] This comparative example provides a preparation method of a non-molecular imprinting sensor, which is the same as step S1 of Example 1, except that it also includes: S2. immersing the washed gold electrode in a phenylalanine-polylysine complex framework solution for adsorption, placing it in a polyfilm solution, and electropolymerizing it to obtain a polyfilm-containing gold electrode; using a mixed solution of acetic acid and water to elute the myclobutanil molecules to prepare a non-molecular imprinting sensor.

[0059] In step S2, the concentration of the phenylalanine-polylysine complex framework solution was 1.0×10 -4 mol / L, the adsorption time was 60 min, and the polymembrane solution was composed of 5.0×10 -4 mol / L o-phenylenediamine solution, 1.0×10 -4 It is prepared by mixing 1 mol / L prochloraz solution with secondary water.

[0060] In step S2, the electropolymerization conditions are as follows: the scanning voltage range is -0.2 to 0.6 V, the polymerization rate is 0.05 V / s for ten cycles; the volume ratio of acetic acid to water in the mixed solution of acetic acid and water is 4:1; and the elution time is 6 minutes.

[0061] Test Example 1

[0062] Voltammetric response of the molecular imprinting sensor based on phenylalanine-prochloraz prepared in the test example

[0063] Reagent preparation: 0.005 mol / L potassium ferrocyanide solution: Use an analytical balance to weigh 0.4116 g of potassium hexacyanoferrate, 0.5280 g of potassium hexacyanoferrate trihydrate, and 2.0 g of potassium chloride into a 50 mL beaker, add deionized water to dissolve, transfer to a 250 mL volumetric flask, dilute to the mark with deionized water, and store in a dark place.

[0064] Test method: Using 0.005 mol / L potassium ferricyanide solution (containing 0.1 mol / L potassium chloride) as a probe molecule, the response of the modified electrode under different conditions in the embodiment was tested by differential pulse voltammetry (DPV), that is, the response of the bare gold electrode, the gold electrode after assembling the phenylalanine-polylysine complex framework, the gold electrode after assembling the prochloraz amine molecule, the gold electrode with a molecularly imprinted polymer, and the molecularly imprinted sensor based on phenylalanine-prochloraz amine in the test embodiment.

[0065] Test results: see Figure 1 .

[0066] from Figure 1It can be seen that when the bare gold electrode (curve "a") is immersed in the phenylalanine-polylysine complex framework solution for adsorption for 60 minutes and the resulting assembled phenylalanine-polylysine complex framework is compared (curve "b"), the assembled phenylalanine-polylysine complex framework hinders the passage of electrons through the electrode surface, thereby significantly decreasing the reduction peak current intensity of the probe molecule.

[0067] The gold electrode after assembling the phenylalanine-polylysine complex framework was placed in a prochloraz solution for hydrogen bonding, and the gold electrode after assembling the prochloraz molecule was obtained (curve "c"). The template molecule prochloraz further blocked the electron transfer and slowed down the electron transfer rate, resulting in a further decrease in the reduction peak current of the probe molecule. -4 mol / L o-phenylenediamine was used to electropolymerize the electrode to obtain a gold electrode with molecularly imprinted polymer (curve "d"), forming a dense and poorly conductive film on the electrode surface, which seriously affected the electron transfer rate and caused the probe molecule reduction peak current intensity to drop sharply.

[0068] The prochloraz in the molecularly imprinted polymer was eluted with an acetic acid: water mixed solution (V / V, 4 / 1) to obtain a molecularly imprinted sensor based on phenylalanine-prochloraz (curve "e"), on which the molecularly imprinted pores can transfer electrons, so the oxidation peak of the probe molecule increases again.

[0069] The electrodes of the phenylalanine-prochloraz molecular imprinting sensor were placed on a 1.0×10 -9 mol / L prochloraz solution was re-adsorbed (curve "f"), so that prochloraz was re-bound to the molecularly imprinted pores, the electron transfer channel was blocked, and the current signal intensity decreased again.

[0070] In summary, it can be seen that the phenylalanine-prochloraz-based molecular imprinting sensor prepared in the example has the ability to recognize prochloraz.

[0071] Test Example 2

[0072] Test the voltammetric response of the non-molecular imprinting sensor prepared in the comparative example

[0073] Reagent preparation: 0.005 mol / L potassium ferrocyanide solution: Use an analytical balance to weigh 0.4116 g of potassium hexacyanoferrate, 0.5280 g of potassium hexacyanoferrate trihydrate, and 2.0 g of potassium chloride into a 50 mL beaker, add deionized water to dissolve, transfer to a 250 mL volumetric flask, dilute to the mark with deionized water, and store in a dark place.

[0074] Test method: Using 0.005 mol / L potassium ferricyanide solution (containing 0.1 mol / L potassium chloride) as the probe molecule, differential pulse voltammetry (DPV) was used to test the response of the modified electrode under different conditions in the comparative example, that is, the response of the bare gold electrode, the gold electrode after assembling the phenylalanine-polylysine complex framework, the gold electrode after the polyfilm, and the non-molecular imprinting sensor in the comparative example was tested.

[0075] Test results: see Figure 2 .

[0076] from Figure 2 It can be seen that when the bare gold electrode (curve "a") is immersed in the phenylalanine-polylysine complex framework solution for adsorption for 60 minutes and the resulting assembled phenylalanine-polylysine complex framework is compared (curve "b"), the assembled phenylalanine-polylysine complex framework hinders the passage of electrons through the electrode surface, thereby significantly decreasing the reduction peak current intensity of the probe molecule.

[0077] 5.0×10 -4 mol / L o-phenylenediamine was used as the polymer base liquid for polymerization to obtain a gold electrode after polymerization (curve "c"). The oxide film formed by o-phenylenediamine on the electrode surface made it difficult for electrons to pass through, and the reduction peak current intensity dropped sharply.

[0078] The non-molecularly imprinted sensor was eluted with a mixed solution of acetic acid and water (V / V, 4 / 1) to obtain a non-molecularly imprinted sensor (curve "d"). -9 mol / L prochloraz solution for 30 min (curve "e"). Curve c does not change much from curves d and e because the non-molecularly imprinted sensor does not contain assembled target molecules. Therefore, elution fails to form molecularly imprinted pores, and the current does not change significantly. The re-adsorbed target molecules cannot be stably present on the molecularly imprinted membrane, thus eliminating the possibility of physical adsorption.

[0079] It can be seen from Experimental Examples 1 and 2 that the molecular imprinting sensor based on phenylalanine-prochloraz provided in the embodiment can specifically recognize prochloraz molecules.

[0080] Test Example 3

[0081] Impedance response of the molecular imprinting sensor based on phenylalanine-prochloraz prepared in the test example

[0082] Test method: Impedance response of the bare gold electrode, the gold electrode after assembling the phenylalanine-polylysine complex framework, the gold electrode after assembling the prochloraz molecule, the gold electrode with the molecularly imprinted polymer, and the molecularly imprinted sensor based on phenylalanine-prochloraz

[0083] Test results: see Figure 3 shown.

[0084] from Figure 3 The bare gold electrode has the lowest resistance (curve "a," 254.732Ω) and the best conductivity. The gold electrode modified with a phenylalanine-polylysine complex framework: The modified phenylalanine-polylysine complex framework hinders electron transfer and reduces current flow, resulting in a higher resistance than the bare electrode (curve "b," 811.551Ω).

[0085] Gold electrode after assembling the prochloraz molecule: After the target molecule prochloraz was fixed, the electron transfer rate further decreased, the current decreased again, and the resistance value further increased (curve "c", 1097.56Ω).

[0086] Gold electrode with molecularly imprinted polymer: After electropolymerization using o-phenylenediamine polyfilm solution, the dense and poorly conductive film on the electrode surface makes it more difficult for electrons to transfer, and the resistance value increases sharply (curve "d", 20386.9Ω).

[0087] Response of the phenylalanine-prochloraz molecular imprinting sensor: After eluting the target molecule prochloraz alone with an eluent, imprinted pores formed on the electrode surface that could transfer electrons, resulting in a decrease in resistance (curve "e", 1376.04Ω). After re-adsorption of the target molecule prochloraz, prochloraz reentered the imprinted pores, hindering electron transfer and causing the resistance to increase again (curve "f", 1634.52Ω).

[0088] In summary, the phenylalanine-prochloraz-based molecular imprinting sensor provided in the examples can specifically recognize prochloraz molecules, which is consistent with the voltammetric response results of Examples 1-2.

[0089] Test Example 4

[0090] Infrared spectroscopy characterization

[0091] Test method: phenylalanine, polylysine, the phenylalanine-polylysine complex framework in the gold electrode after assembling the phenylalanine-polylysine complex framework provided in the embodiment, the phenylalanine-polylysine-prochloraz in the gold electrode after assembling the prochloraz molecule provided in the embodiment, and prochloraz were tested respectively.

[0092] Test results: see Figure 4 and Figure 5 .

[0093] The infrared spectra of phenylalanine (curve "a"), polylysine (curve "b") and phenylalanine-polylysine complex framework (curve "c") are shown in Figure 2. Figure 4As shown, phenylalanine is at 2550.37~3067.97cm -1 There is an NH stretching absorption peak at 1587.37 cm -1 There is a hydroxyl absorption peak at 1566.09 cm -1 There is a strong absorption peak at 1669.11 cm -1 There is a stretching vibration peak of -C=O at 3451.30cm -1 The NH absorption peak of amide was generated at , which proved that phenylalanine and polylysine were combined in an amide manner and the phenylalanine-polylysine complex framework was successfully constructed.

[0094] The infrared spectra of phenylalanine-polylysine-prochloraz (curve "d") and prochloraz (curve "e") are shown in Figure 2. Figure 5 As shown. Curve "e" is at 3451.30cm -1 、1669.11cm -1 、1566.09cm -1 There is a characteristic absorption curve of benzene ring at 1239.40 cm -1 There is a COC characteristic absorption peak at 600~800cm -1 There is a C-Cl absorption peak at 3450.88cm. Comparing the peak positions of the characteristic peaks of c, d, and e, the curve "d" is at 3450.88cm -1 There is an amide NH absorption peak at 591.96 cm -1 The characteristic absorption peak of -NH2 at 1015.39cm -1 The CN absorption peak shifts.

[0095] In summary, the phenylalanine-polylysine complex framework in the embodiment is successfully combined with the prochloraz molecule through hydrogen bonds to form a phenylalanine-polylysine-prochloraz complex.

[0096] Test Example 5

[0097] The current response signals of the phenylalanine-prochloraz-based molecular imprinting sensor provided in the test example were measured in prochloraz solutions with different concentrations.

[0098] Test method: Prochloraz concentration a→h are 1.0×10 -15 mol / L、5.0×10 -15 mol / L、7.0×10 - 15 mol / L、1.0×10 -14 mol / L、5.0×10 -14 mol / L、7.0×10-14 mol / L、1.0×10 -13 mol / L、5.0×10 - 13 mol / L. The current response signals of the molecular imprinting sensors based on phenylalanine-prochloraz provided in the test examples were tested respectively.

[0099] Test results: see Figure 6 .

[0100] from Figure 6 It can be seen that the change value of the sensor response signal intensity decreases with the increase of the logarithm of the concentration of prochloraz solution (logC), and at 1.0×10 -15 mol / L to 5.0×10 -13 mol / L range showed a good positive correlation, and the detection limit was 9.2231×10 -16 mol / L, the linear equation is Δi(μA)=189.19+12.4673lgC(mol / L), and the correlation coefficient r=0.9997.

[0101] Test Example 6

[0102] Reproducibility, stability and service life of the molecular imprinting sensor based on phenylalanine-prochloraz provided in the test example

[0103] For 1.0×10 -13 The determination was performed using a 10 mol / L prochloraz solution, and the determination was repeated 6 times. The relative standard deviation (RSD) of the results of the 6 measurements was 5.1%. Therefore, the molecular imprinting sensor based on phenylalanine-prochloraz provided in the embodiment has good stability.

[0104] Under the same conditions and in the same way, six molecular imprinting sensors were prepared and the concentration of 1.0×10 - 13 The current value was measured using a 10 mol / L prochloraz solution, and the relative standard deviation (RSD) of the measured current value was 4.7%. Therefore, the molecular imprinting sensor based on phenylalanine-prochloraz provided in the embodiment has good reproducibility.

[0105] The molecular imprinted sensors prepared in the same batch were stored in a refrigerator in the dark for 3 days. -13 mol / L prochloraz solution, the current signal decreased by an average of 3.2%. -13 mol / L prochloraz solution was used for measurement, and the current signal decreased by 8.7% on average. Therefore, the molecular imprinting sensor based on phenylalanine-prochloraz provided in the embodiment has a long service life.

[0106] Test Example 7

[0107] Anti-interference ability of the molecular imprinting sensor based on phenylalanine-prochloraz provided in the test example

[0108] Test method: Pesticides and common anions and cations that are often mixed with prochloraz in agricultural production were selected as interfering substances. The interfering substances are as follows: thiacloprid, propoxur, thiamethoxam, carbendazim, isoprocarb, and anions and cations (Na + 、Cl — , K + ).

[0109] The molecular imprinting sensor based on phenylalanine-prochloraz provided in the embodiment was used to detect thiacloprid, propoxur, thiamethoxam, carbendazim, isoprocarb, and anions and cations (Na + 、Cl — , K + ) were re-adsorbed at a concentration of 1.0×10 -10 The abilities of the phenylalanine-prochloraz-based molecular imprinting sensors provided in the examples to recognize the interfering substance and the target molecule prochloraz were compared.

[0110] Test results: see Figure 7 .

[0111] from Figure 7 It can be seen that the maximum current response signal value among the interfering substances is only 5.6% of the response signal value of prochloraz. Therefore, the molecular imprinting sensor based on phenylalanine-prochloraz provided in the embodiment can highly selectively identify prochloraz molecules, but has low recognition ability for interfering particles.

[0112] Test Example 8

[0113] Sample testing

[0114] Preparation of sample solution: Peel and cut apples purchased from the market into small pieces, grind into a homogenate, weigh 10.0 g and place in a centrifuge tube, centrifuge at 2500 rpm for 20 min, take the supernatant, transfer it to a 100 mL volumetric flask, dilute to volume with secondary water to prepare the sample solution, and store in a refrigerator.

[0115] Test method: 10 mL of sample solution was placed in a small beaker, and the molecular imprinting sensor based on phenylalanine-prochloraz provided in the example was placed in the sample solution for re-adsorption for 30 minutes. The DPV response current intensity was detected, and the accuracy of the sensor was verified using the spike recovery method.

[0116] Test results: See Table 1.

[0117]

[0118] As shown in Table 1, the recoveries of the phenylalanine-prochloraz molecular imprinting sensor provided in the examples for detecting prochloraz in samples ranged from 97.0% to 104.0%. Therefore, the sensor can effectively measure the content of prochloraz molecules and has practical application capabilities.

[0119] In summary, the molecular imprinting sensor based on phenylalanine-prochloraz prepared by the preparation method provided by the present invention can quickly, efficiently and sensitively identify prochloraz molecules, and has strong anti-interference ability. Compared with traditional molecular imprinting sensors, the molecular imprinting sensor prepared using the phenylalanine-polylysine composite framework of the present invention has a significantly improved selectivity detection limit, a wide range of applications, strong practicality, is not limited by the material structure and functional group type, and can be used for the detection of pesticide residue molecules.

[0120] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and description of the present invention.

Claims

1. A method for preparing a molecular imprinting sensor based on phenylalanine-prochloraz, characterized in that: The preparation method comprises the following steps: S1. Soak a bare gold electrode in dilute nitric acid, rinse it, and then ultrasonicate it in anhydrous ethanol. Polish the suede surface with alumina polishing powder. Cyclic voltammetry is performed using a mixed solution of K₄[Fe(CN)₆] / K₃[Fe(CN)₆] and KCl as a probe molecule until the potential difference is no greater than 120 mV. This yields a cleaned gold electrode. S2. Immersing the washed gold electrode in a phenylalanine-polylysine complex framework solution for adsorption to obtain a gold electrode assembled with a phenylalanine-polylysine complex framework, then placing it in a prochloraz solution for hydrogen bonding to obtain a gold electrode assembled with prochloraz molecules, and electropolymerizing it with o-phenylenediamine to obtain a gold electrode with a molecularly imprinted polymer; S3. The gold electrode with the molecularly imprinted polymer is used to elute the prochloraz molecules with a mixed solution of acetic acid and water to obtain the phenylalanine-prochloraz-based molecular imprinting sensor.

2. The method for preparing a molecular imprinting sensor based on phenylalanine-prochloraz according to claim 1, characterized in that: In step S1, the concentration of the dilute nitric acid is 1 mol / L, the soaking time is 5 min, and the ultrasonication time is 3 min.

3. The method for preparing a molecular imprinting sensor based on phenylalanine-prochloraz according to claim 1, characterized in that: In step S1, the size of the aluminum oxide polishing powder is 0.03 μm.

4. The method for preparing a molecular imprinting sensor based on phenylalanine-prochloraz according to claim 1, wherein: In step S1, the concentrations of K4[Fe(CN)6] / K3[Fe(CN)6] and KCl in the mixed solution of K4[Fe(CN)6] / K3[Fe(CN)6] and KCl are 5.0×10 -3 mol / L, 0.1mol / L.

5. The method for preparing a molecular imprinting sensor based on phenylalanine-prochloraz according to claim 1, wherein: In step S2, the concentration of the phenylalanine-polylysine complex framework solution is 1.0×10 -4 mol / L, and the adsorption time is 60 min.

6. The method for preparing a molecular imprinting sensor based on phenylalanine-prochloraz according to claim 1, wherein: In step S2, the concentration of the prochloraz solution is 1.0×10 -4 mol / L, and the hydrogen bond binding time is 30 min.

7. The method for preparing a molecular imprinting sensor based on phenylalanine-prochloraz according to claim 1, wherein: In step S2, the concentration of o-phenylenediamine is 5.0×10 -4 moL / L; the conditions for electropolymerization: the scanning voltage range is -0.2 to 0.6V, and the film is polymerized ten times at a rate of 0.05V / s.

8. The method for preparing a molecular imprinting sensor based on phenylalanine-prochloraz according to claim 1, characterized in that: In step S3, the volume ratio of acetic acid to water in the mixed solution of acetic acid and water is 4:1, and the elution time is 6 minutes.

9. The method for preparing a molecular imprinting sensor based on phenylalanine-prochloraz according to claim 1, characterized in that: The preparation method of the phenylalanine-polylysine complex framework solution comprises the following steps: S101. To a 50.0 mL three-necked round-bottom flask, 16.5189 g of DL-β-phenylalanine was added. A magnetic stirrer was turned on and 25.00 mL of thionyl chloride was slowly added dropwise. The mixture was allowed to react in a fume hood for 2 h. The excess thionyl chloride was removed by rotary evaporation under reduced pressure to obtain a solid powder of phenylalanine chloride. S102. Weigh 0.0385 g of polylysine into a beaker, add 30 mL of 0.2 mol / L NaOH solution, add 0.0165 g of phenylalanine chloride, stir and dissolve with a magnetic stirrer, transfer to a 100 mL volumetric flask, and dilute to volume with secondary water to obtain the phenylalanine-polylysine complex framework solution, which is then refrigerated.

10. A molecular imprinting sensor based on phenylalanine-prochloraz prepared by the preparation method according to any one of claims 1 to 9.

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