CN109021283B

CN109021283B - CsPbBr for detecting omethoate3Perovskite quantum dot-molecularly imprinted fluorescent sensor and preparation method thereof

Info

Publication number: CN109021283B
Application number: CN201810358830.XA
Authority: CN
Inventors: 梁勇; 郭慢丽
Original assignee: South China Normal University
Current assignee: South China Normal University
Priority date: 2018-04-19
Filing date: 2018-04-19
Publication date: 2021-01-26
Anticipated expiration: 2038-04-19
Also published as: CN109021283A

Abstract

The invention relates to CsPbBr for detecting omethoate₃The preparation method of the perovskite quantum dot-molecular imprinting fluorescence sensor comprises the following steps: s1: preparation of APTES-capped CsPbBr₃Perovskite quantum dots; s2: preparation of CsPbBr₃Perovskite quantum dots-molecularly imprinted polymers; s3: and eluting the template molecule omethoate. The invention also provides CsPbBr for detecting omethoate₃Perovskite quantum dot-molecularly imprinted fluorescent sensor, CsPbBr₃The perovskite quantum dot-molecularly imprinted fluorescent sensor is prepared according to the preparation method. The preparation method provided by the invention has the advantages of mild reaction conditions, high reaction speed and high yield; the CsPbBr provided by the invention₃The perovskite quantum dot-molecular imprinting fluorescence sensor has the characteristics of high sensitivity and specificity identification on omethoate, the linear detection range is 50-400ng/mL, the linear correlation coefficient is 0.997, the detection limit is 18.8ng/mL, and the detection precision is 1.7% (RSD).

Description

CsPbBr for detecting omethoate3Perovskite quantum dot-molecularly imprinted fluorescent sensor and preparation method thereof

Technical Field

The invention belongs to the field of analytical chemistry, and particularly relates to CsPbBr for detecting omethoate₃A perovskite quantum dot-molecular imprinting fluorescence sensor and a preparation method thereof.

Background

Omethoate detection is a hot spot in research and development of food safety fields at home and abroad, and at present, methods such as gas chromatography, liquid chromatography, immunoassay, gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS) and the like are mainly adopted. Chromatography-mass spectrometry has high detection sensitivity but is expensive. Chromatographic detection has high limit, and can not meet the actual requirements of trace pesticide residue and export trade detection, so enrichment is usually required before analysis. The pretreatment methods adopted at present mainly comprise solid phase extraction, liquid-liquid extraction, matrix dispersion solid phase extraction, solid phase micro-extraction, supercritical fluid extraction, column chromatography and the like. Since matrix solid phase dispersion extraction has the advantages of less sample consumption, less consumption of organic solvent and the like, the matrix solid phase dispersion extraction is widely applied to analysis of drugs, organic pollutants and natural products in environment, biology and food. However, the solid phase dispersion extraction adsorbent based on commercial matrix is often poor in selectivity, the acting force between the target and the adsorbent is nonspecific, the efficiency of extraction and purification is not high, the interference of the matrix is difficult to completely remove, and the cost is also high. Therefore, the synthesis of adsorption functional materials with specific recognition ability to omethoate by using molecular imprinting technology is a trend.

Over the past two decades, photoluminescent semiconductor Quantum Dots (QDs) have attracted considerable attention due to their excellent photostability, broad absorption spectrum, narrow symmetric emission and adjustable size. They have wide application prospects in the fields of bio-imaging, Light Emitting Diodes (LEDs), solar cells, and particularly sensors. Therefore, in order to improve the selectivity of QD-based sensors, Molecularly Imprinted Polymers (MIPs) were introduced to synthesize MIP @ QDs fluorescence sensors to selectively detect analytes. The molecular imprinting technology is a mature technology for establishing a customized binding site and memorizing the shape, size and functional group of a template. MIPs have the characteristics of strong affinity, high selectivity, easy preparation, low cost and the like, so the MIPs are increasingly applied to some important application fields of biomimetic sensors, chromatographic separation, solid-phase extraction, controlled release of drug delivery, catalysis and the like. To date, a number of MIP-terminated QDs fluorescence sensors have been developed that combine MIP selectivity with QDs sensitivity to detect various compounds, such as cytochrome c, 4-nitrophenol, pyrethroids, melamine and ractopamine. Currently, common quantum dots used as luminescent elements of fluorescent sensors are composed of group IV, II-VI, IV-VI or III-V elements, such as CdSe, CdTe, CdS, Si, C, ZnS quantum dots, and the like. However, these quantum dots as the sensing element have a disadvantage of low sensitivity of the sensor due to their low quantum yield. Therefore, there is a great need to develop novel semiconductor quantum dots having excellent photoluminescence properties and high fluorescence quantum yield.

More recently, having the formula ABX₃(wherein A ═ Cs⁺、CH₃NH₃ ⁺；B＝Pb、Sn、Ge；X＝Br^-、I^-、Cl^-) Due to their tunable optical band gap, high emission efficiency and excellent charge transport properties, perovskites of have attracted considerable attention and have shown great potential in many areas of solar cells, photovoltaic cells, light emitting diodes and lasers. All Inorganic Metal Halide (IMH) perovskite quantum dots (CsBX)₃，B＝Pb、Sn、Ge；X＝Br^-、I^-、Cl^-While having the advantages of both QDs and halide perovskites. all-Inorganic Metal Halide (IMH) perovskites have greater stability than organic-inorganic metal halide (OMH) perovskites. In addition, such inorganic perovskite quantum dots have high Photoluminescence (PL) Quantum Yield (QYs). Wherein CsPbBr₃The photoluminescence quantum yield of the perovskite quantum dot is more than 90%, and the perovskite quantum dot is a novel quantum dot material with growth potential. Although CsPbBr₃The perovskite quantum dot has higher Photoluminescence (PL) Quantum Yield (QYs), CsPbBr₃The stability of perovskite quantum dots in water and oxygen remains a significant challenge.

Therefore, the invention develops CsPbBr for detecting omethoate₃The perovskite quantum dot-molecular imprinting fluorescence sensor has the advantages of high sensitivity and specificity identification on omethoate.

Disclosure of Invention

The technical problem to be solved by the invention is to provide CsPbBr for detecting omethoate aiming at the defects in the prior art₃The preparation method of the perovskite quantum dot-molecularly imprinted fluorescent sensor has the advantages of simple steps, mild reaction conditions and high reaction speed; prepared CsPbBr₃Perovskite quantum dot-molecular imprinting fluorescence transmissionThe sensor can detect omethoate in a sample quickly, with high sensitivity and specificity.

In order to achieve the purpose, the invention adopts the following technical scheme:

CsPbBr for detecting omethoate₃The preparation method of the perovskite quantum dot-molecular imprinting fluorescence sensor comprises the following steps:

s1: preparation of APTES-capped CsPbBr₃Perovskite quantum dots

Adding 3-Aminopropyltriethoxysilane (APTES) into cesium carbonate, octadecene, and PbBr₂Stirring in the mixture of oleic acid and oleylamine for 3 hours at 20 ℃ and 40% humidity in the presence of air, hydrolyzing, and purifying to obtain the APTES-terminated CsPbBr₃Perovskite quantum dots;

s2: preparation of CsPbBr₃Perovskite quantum dot-molecularly imprinted polymer

Oxidizing the template molecule with dimethoate, octadecene and the APTES-terminated CsPbBr obtained in the step S1₃Mixing and stirring the perovskite quantum dots and the residual 3-Aminopropyltriethoxysilane (APTES) reacted in the step S1 for 30 minutes, adding a cross-linking agent, and stirring for 12 hours to obtain CsPbBr₃Perovskite quantum dots-molecularly imprinted polymers;

s3: elution template molecular oxidation dimethoate

CsPbBr obtained in step S2₃Centrifuging the perovskite quantum dot-molecularly imprinted polymer, removing supernatant, removing template molecule with eluent to oxidize dimethoate, and obtaining CsPbBr₃Perovskite quantum dot-molecularly imprinted fluorescence sensor.

Preferably, the step S1 includes:

1) mixing cesium carbonate, oleic acid and octadecene, degassing for 10 minutes in vacuum, heating to 120 ℃ under the vacuum condition, keeping the temperature constant for 1 hour, heating to 150 ℃ under the condition of introducing nitrogen, keeping the temperature constant for 2 hours until the solution is clear, and preparing a cesium oleate solution;

2) octadecene and PbBr₂Mixing, vacuum degassing for 10 min, vacuum drying at 120 deg.C for 1 hr, introducing nitrogen,adding oleic acid, oleylamine and 3-Aminopropyltriethoxysilane (APTES), allowing the solution to settle, and heating to 160 deg.C;

3) preheating the cesium oleate solution prepared in the step 1) to 100 ℃, quickly injecting the preheated cesium oleate solution into the solution in the step 2), cooling the solution to room temperature by using an ice water bath after 5 seconds, stirring for 3 hours under the conditions of temperature of 20 ℃, humidity of 40% and air, and hydrolyzing;

4) centrifuging at 5000rpm for 10 min, washing with hexane for 2 times to obtain APTES-capped CsPbBr₃Perovskite quantum dots.

Particularly preferably, in the step 1), the molar volume ratio of the cesium carbonate to the oleic acid and the octadecene is 1mmol to (1.0-1.1) ml to (12.0-12.3) ml.

Particularly preferably, in step 2), the PbBr is₂And octadecene, oleic acid, oleylamine, 3-Aminopropyltriethoxysilane (APTES) in a molar volume ratio of 1mmol: (20-30) ml: (0.2-0.3) ml: (3-4.5) ml.

Particularly preferably, in step 3), the cesium oleate solution and PbBr₂The molar volume ratio of (2-3) ml to 1 mmol.

Preferably, in step S2, the molar volume ratio of the template molecule omethoate and the octadecene is 1 mol: (8-12) L.

Particularly preferably, in step S2, the molar volume ratio of the template molecule omethoate to the octadecene is 1 mol: 10L.

Preferably, in step S2, the molar ratio of the template molecular omethoate to the APTES-terminated CsPbBr3 perovskite quantum dots is 1: (1 × 10)^-6-3×10^-6)。

Particularly preferably, in step S2, the template molecule omethoate and APTES-capped CsPbBr₃The molar ratio of the perovskite quantum dots is 1 to (1.88 multiplied by 10)^-6)。

Preferably, in step S2, the molar ratio of the template molecule omethoate to the residual 3-Aminopropyltriethoxysilane (APTES) is 1: (3-5).

Particularly preferably, the mole ratio of the template molecule omethoate to the rest of the reaction 3-Aminopropyltriethoxysilane (APTES) is 1: 3.

Preferably, in step S2, the cross-linking agent is tetramethyl orthosilicate, and the molar volume ratio of the template molecule omethoate to the tetramethyl orthosilicate is 1 mol: (75-125) ml.

Particularly preferably, the molar volume ratio of the template molecule omethoate to the tetramethyl orthosilicate is 1 mol: 100 ml.

Preferably, in step S3, the eluent is a mixture of hexane and ethyl acetate, and the volume ratio of hexane to ethyl acetate is 1: 3.

The invention also provides CsPbBr for detecting omethoate₃Perovskite quantum dot-molecularly imprinted fluorescent sensor, CsPbBr₃The perovskite quantum dot-molecularly imprinted fluorescent sensor is prepared according to the preparation method.

The invention has the beneficial effects that:

1. the preparation method provided by the invention has the advantages of mild reaction conditions, high reaction speed and high yield, and is a simple, convenient and efficient method for preparing CsPbBr with high sensitivity and specificity recognition on omethoate₃A preparation method of the perovskite quantum dot-molecular imprinting fluorescence sensor;

2. in the invention, APTES is directly added into cesium carbonate, octadecene and PbBr₂In the reaction mixture of oleic acid and oleylamine, the APTES-terminated CsPbBr is synthesized in one step₃Quantum dots, then capturing the trace water vapor in the air and reacting with APTES, the surface of the quantum dots, thereby gradually forming a silica matrix, the silica is optically transparent and inert and is an ideal coating for protecting the luminescent quantum dots, so that CsPbBr₃The quantum dots are protected; at the same time, APTES is taken as a functional monomer to synthesize CsPbBr₃The perovskite quantum dot-molecular imprinting fluorescence sensor has high sensitivity;

3. CsPbBr of the invention₃The perovskite quantum dot-molecular imprinting fluorescence sensor performs a fluorescence titration experiment on omethoate to obtain a detection sample with a linear detection range of 50-400ng/mL and a linear correlation coefficient of 0.997The limit is 18.8ng/mL, and the detection precision is 1.7 percent (RSD);

4. CsPbBr of the invention₃The perovskite quantum dot-molecular imprinting fluorescence sensor carries out selectivity test, and proves that CsPbBr of the invention₃The perovskite quantum dot-molecular imprinting fluorescence sensor has good selectivity on omethoate;

6. CsPbBr of the invention₃The perovskite quantum dot-molecular imprinting fluorescence sensor is applied to the labeling detection of omethoate in an actual sample and the direct detection of ultra-trace omethoate residues in agricultural products, the recovery rate in the surface labeling detection is 96.7-101%, and the relative standard deviation is less than 4.21%; the test results show that the CsPbBr of the invention₃The perovskite quantum dot-molecular imprinting fluorescence sensor has practical detection value and significance for omethoate.

Drawings

FIG. 1 is a process flow diagram of the preparation process according to the invention;

FIG. 2 is a scheme for the preparation of CsPbBr₃A test result diagram for optimizing the addition amount of the cross-linking agent in the perovskite quantum dot-molecularly imprinted fluorescent sensor;

FIG. 3 is a scheme for the preparation of CsPbBr₃An optimized molar ratio test result graph of template molecule omethoate and APTES in the perovskite quantum dot-molecular imprinting fluorescence sensor;

FIG. 4 is APTES capped CsPbBr₃UV-vis absorption and PL emission spectra of the quantum dot solution;

FIG. 5 is APTES capped CsPbBr₃Time-resolved PL decay spectrum of quantum dots under 365nm excitation;

FIG. 6 is APTES capped CsPbBr₃An energy dispersive X-ray (EDX) spectrogram of quantum dots;

FIG. 7 is CsPbBr₃Quantum dot and APTES-terminated CsPbBr₃Quantum dots, CsPbBr₃Perovskite quantum dot-molecular imprinting fluorescence sensor (MIP @ CsPbBr)₃QDs);

FIG. 8 shows CsPbBr (without template molecule eluted)₃Perovskite quantum dot-molecularly imprinted polymer, CsPbBr₃Perovskite quantum dot-fractionSubscription fluorescence sensor and CsPbBr₃A fluorescence excitation/emission spectrum of the perovskite quantum dot-molecular non-imprinted fluorescence sensor;

FIG. 9 is a pure silica, APTES capped CsPbBr₃Quantum dots, CsPbBr₃An XRD representation diagram of the perovskite quantum dot-molecular imprinting fluorescence sensor;

FIG. 10 is CsPbBr₃Quantum dot and APTES-terminated CsPbBr₃Quantum dots and CsPbBr₃Transmission electron microscopy characterization (TEM) image of perovskite quantum dot-molecularly imprinted fluorescent sensor, wherein FIG. 10(a) is CsPbBr₃Transmission electron microscopy results of the quantum dots, and FIG. 10(b) shows CsPbBr₃High resolution projection Electron microscopy of Quantum dots, FIG. 10(c) is APTES capped CsPbBr₃Transmission electron microscopy results of the quantum dots, CsPbBr in FIG. 10(d)₃Transmission electron microscope results of perovskite quantum dot-molecularly imprinted fluorescent sensor;

FIG. 11 is CsPbBr₃Perovskite quantum dot-molecular imprinting fluorescence sensor and CsPbBr₃A perovskite quantum dot-molecular non-imprinted fluorescent sensor adsorption kinetics test result graph;

FIG. 12 is temperature vs CsPbBr₃A perovskite quantum dot-molecular imprinting fluorescence sensor is used for determining an influence test result graph of omethoate;

FIG. 13 shows the different polarity organic solvent pair MIP @ CsPbBr₃A graph of the results of the test on the influence of QDs recognition performance; wherein, FIG. 13(a) shows the different polarity organic solvent pair MIP @ CsPbBr₃Graphs of the results of the effects of QDs optical properties; FIG. 13(b) MIP @ CsPbBr₃QDs is the fluorescence spectrum in different polar organic solutions;

FIG. 14 is CsPbBr₃A fluorescence response test result graph of the perovskite quantum dot-molecular imprinting fluorescence sensor to omethoate with different concentrations;

FIG. 15 is CsPbBr₃A fluorescence response test result graph of the perovskite quantum dot-molecular non-imprinted fluorescence sensor to omethoate with different concentrations;

FIG. 16 shows the concentration of omethoate versus CsPbBr₃Perovskite quantumCalibration curve of point-molecularly imprinted fluorescent sensor;

FIG. 17 is a graph of omethoate versus CsPbBr at various concentrations₃A calibration curve of the perovskite quantum dot-molecular non-imprinted fluorescent sensor;

FIG. 18 is CsPbBr₃Perovskite quantum dot-molecular imprinting fluorescence sensor and CsPbBr₃And (3) a selective test result diagram of the perovskite quantum dot-molecular non-imprinted fluorescent sensor on omethoate and structural analogues thereof.

Detailed Description

As shown in FIG. 1, the invention provides CsPbBr for detecting omethoate₃The preparation method of the perovskite quantum dot-molecular imprinting fluorescence sensor comprises the following steps:

s1: preparation of APTES-capped CsPbBr₃Perovskite quantum dots

Adding 3-Aminopropyltriethoxysilane (APTES) to cesium carbonate (Cs)₂CO₃) Octadecene (ODE), PbBr₂Mixing oleic acid (0A) and oleylamine (OAm), stirring at 20 deg.C and 40% humidity for 3 hr, hydrolyzing, and purifying to obtain APTES-capped CsPbBr₃Perovskite quantum dots;

Oxidizing the template molecules with dimethoate (OMT), octadecene and the APTES-terminated CsPbBr obtained in the step S1₃Mixing and stirring the perovskite quantum dots and the residual 3-Aminopropyltriethoxysilane (APTES) reacted in the step S1 for 30 minutes, adding a cross-linking agent, and stirring for 12 hours to obtain CsPbBr₃Perovskite quantum dots-molecularly imprinted polymers;

s3: elution template molecular oxidation dimethoate

The invention also provides a method for detecting the Oxycor prepared by the preparation methodCsPbBr of fruit₃Perovskite quantum dot-molecularly imprinted fluorescence sensor.

The various test devices and reagents are commercially available and commercially available.

The technical solution of the present invention is further described below by using specific preferred embodiments in combination with preparation process test examples, structure characterization test examples, detection condition test examples, and effect test examples, but the present invention is not limited to the following embodiments.

Example 1:

preparation of APTES-terminated CsPbBr₃Perovskite quantum dots

1) Adding 0.32g of cesium carbonate, 1ml of oleic acid (90%, OA) and 12ml of octadecene (90%, ODE) into a 50ml three-neck round-bottom flask, carrying out vacuum degassing on a Schlenk line for 10 minutes, heating to 120 ℃ under a vacuum condition, keeping the temperature constant for 1 hour, then heating to 150 ℃ under a nitrogen-introduced condition, keeping the temperature constant for 2 hours until the solution is clear, and thus obtaining a cesium oleate solution;

2) 10ml of octadecene (90%, ODE) and 0.376mmol of PbBr₂Loading into a 50ml three-necked round bottom flask, degassing for 10 minutes under vacuum, and vacuum drying at 120 ℃ for 1 hour, then switching the flask to nitrogen atmosphere, slowly adding 100. mu.l oleic acid (90%, OA), 100. mu.l oleylamine (80% -90%, OAm), and 1ml 3-Aminopropyltriethoxysilane (APTES) to the flask, and heating to 160 ℃ until the solution is clear;

3) preheating the cesium oleate solution prepared in the step 1) to 100 ℃, quickly injecting 1ml of the preheated cesium oleate solution into the solution in the step 2), cooling the solution to room temperature by using an ice water bath after 5 seconds, then opening a flask, stirring for 3 hours under the conditions of temperature of 20 ℃, humidity of 40% and air, hydrolyzing, and forming an organic silicon substrate through silanization;

4) centrifuging at 5000rpm for 10 min, washing with hexane for 2 times to obtain APTES-capped CsPbBr₃Perovskite quantum dots; the prepared APTES-terminated CsPbBr₃The perovskite quantum dots are dispersed in n-hexane for storage, and the molar concentration of the perovskite quantum dots is 0.376 multiplied by 10^-4mol/L。

(II) preparation of CsPbBr₃Perovskite quantum dot-molecularly imprinted polymer

To a 25mL flask was added 1mmol of the template molecule Omethoate (OMT), 10mL octadecene (90%, ODE), 50. mu.L of the APTES capped CsPbBr obtained in step one₃The perovskite quantum dot is prepared by taking the residual 3-Aminopropyltriethoxysilane (APTES) in the first step reaction as a functional monomer, mixing and stirring for 30 minutes, adding 100ul of tetramethyl orthosilicate (TMOS) into the mixture, and stirring for 12 hours to obtain CsPbBr₃Perovskite quantum dots-molecularly imprinted polymers.

(III) elution template molecule omethoate

The CsPbBr obtained in the step two₃Centrifuging the perovskite quantum dot-molecularly imprinted polymer at a rotating speed, removing supernatant, washing with hexane/ethyl acetate mixed solution (the volume ratio of hexane to ethyl acetate is 1: 3) for 10 times, removing template molecular Omethoate (OMT), and obtaining CsPbBr₃Perovskite quantum dot-molecular imprinting fluorescence sensor (MIP @ CsPbBr)₃ QDs)。

Comparative example 1

Preparation of APTES-terminated CsPbBr₃Perovskite quantum dots

In this comparative example, the above-mentioned APTES-capped CsPbBr was used₃The perovskite quantum dots are prepared by the same method as in example 1.

(II) preparation of CsPbBr₃Perovskite quantum dot-molecular non-imprinted polymer

A25 mL flask was charged with 10mL octadecene (90%, ODE), 50. mu.L of APTES capped CsPbBr obtained in step one₃The perovskite quantum dot is prepared by taking the residual 3-Aminopropyltriethoxysilane (APTES) in the first step reaction as a functional monomer, mixing and stirring for 30 minutes, adding 100 mu l of tetramethyl orthosilicate (TMOS) into the mixture, and stirring for 12 hours to obtain CsPbBr₃Perovskite quantum dots-molecularly non-imprinted polymers.

(III) elution

The CsPbBr obtained in the step two₃Centrifuging the perovskite quantum dot-molecular non-imprinted polymer at a rotating speed, removing supernatant,washing with hexane/ethyl acetate mixture (volume ratio of hexane to ethyl acetate is 1: 3) for 10 times to obtain CsPbBr₃Perovskite quantum dot-molecular non-imprinted fluorescence sensor (NIP @ CsPbBr)₃ QDs)。

Comparative example 1

(I) preparation of CsPbBr₃Perovskite quantum dots

CsPbBr as described above in this comparative example₃The perovskite quantum dots were prepared as in example 1, but without the addition of 3-Aminopropyltriethoxysilane (APTES).

To a 25mL flask was added 1mmol of the template molecule Omethoate (OMT), 10mL octadecene (90%, ODE), 50. mu.L of the APTES capped CsPbBr obtained in step one₃Perovskite quantum dots and 3mmol 3-Aminopropyltriethoxysilane (APTES) as functional monomers, mixing and stirring for 30 minutes, adding 100 μ l tetramethyl orthosilicate (TMOS) into the mixture, stirring for 12 hours to obtain CsPbBr₃Perovskite quantum dots-molecularly imprinted polymers.

(III) elution template molecule omethoate

The CsPbBr obtained in the step two₃Centrifuging the perovskite quantum dot-molecularly imprinted polymer at a rotating speed, removing supernatant, washing with hexane/ethyl acetate mixed solution (the volume ratio of hexane to ethyl acetate is 1: 3) for 10 times, removing template molecule Omethoate (OMT), and obtaining the APTES-free terminated CsPbBr₃Perovskite quantum dot-molecularly imprinted fluorescence sensor.

Preparation Process test example 1:

optimization of the amount of crosslinking agent tetramethyl orthosilicate (TMOS).

The test method comprises the following steps: except for the crosslinking agent, the same amounts of all the compounds as in example 1/comparative example 1 were used, and 50. mu.l, 100. mu.l and 150. mu.l of Tetramethylorthosilicate (TMOS) were added to prepare CsPbBr₃Perovskite quantum dot-molecular imprinting fluorescence sensor (MIP @ CsPbBr)₃QDs) and CsPbBr₃Perovskite quantum dot-molecular non-imprinted fluorescence sensor (NIP @ CsPbBr)₃QDs)。

The prepared CsPbBr₃Perovskite quantum dot-molecular imprinting fluorescence sensor (MIP @ CsPbBr)₃QDs) and CsPbBr₃Perovskite quantum dot-molecular non-imprinted fluorescence sensor (NIP @ CsPbBr)₃QDs) were dispersed in methylene chloride to a concentration of 5 × 10^-6g/mL solution, under the condition of 25 ℃, fully interacting with 300ng/mL Omethoate (OMT) for 30 minutes, and testing MIP @ CsPbBr before and after the action with the Omethoate (OMT) by using a fluorescence spectrometer₃QDs and corresponding NIP @ CsPbBr₃Fluorescence intensity of QDs at 510 nm. Specific recognition ability of imprinted polymers was evaluated by Imprinted Factor (IF). The formula for the print factor is as follows:

IF＝ΔF_{(MIP@CsPbBr3 QDs)}/ΔF_{(NIP@CsPbBr3 QDs)}

wherein, Δ F_{(MIP@ CsPbBr3 QDs)}Denotes MIP @ CsPbBr₃Difference between fluorescence intensity before and after re-adsorption of QDs solution to template ((F)₀-F)/F)，ΔF_{(NIP@ CsPbBr3 QDs)}Denotes NIP @ CsPbBr₃Difference in fluorescence intensity before and after re-adsorption of QDss solution to template ((F)₀-F)/F)。

Fluorescence test conditions: 365nm is adopted as an excitation wavelength, the width of an excitation light slit is 5nm, the width of an emission light slit is 10nm, and the voltage of a photomultiplier is 400V; the measurements were performed using a quartz cell (1cm path length).

The test results are shown in FIG. 2.

As can be seen from fig. 2, IF is highest when the amount of the crosslinking agent TMOS is 100 μ L, too high addition amount of TMOS may cause excessive crosslinking to cause aggregation of the polymer, and too low addition amount of TMOS may cause insufficient crosslinking and insufficient formation of embossed sites. Therefore, the most preferable amount of TMOS added is 100. mu.L, and the molar volume ratio of the template molecular omethoate to TMOS is 1 mol: 100 ml.

Preparation Process test example 2:

optimizing the proportion of the template molecule Omethoate (OMT) and the functional monomer 3-aminopropyl triethoxysilane (APTES).

The test method comprises the following steps: CsPbBr was prepared as shown in Table 1 (5 kinds of template molecular omethoate and APTES in a molar ratio, and other compounds were used in the same amounts as in example 1/comparative example 1)₃Perovskite quantum dot-molecular imprinting fluorescence sensor (MIP @ CsPbBr)₃QDs) and CsPbBr₃Perovskite quantum dot-molecular non-imprinted fluorescence sensor (NIP @ CsPbBr)₃ QDs)。

The prepared CsPbBr₃Perovskite quantum dot-molecular imprinting fluorescence sensor (MIP @ CsPbBr)₃QDs) and CsPbBr₃Perovskite quantum dot-molecular non-imprinted fluorescence sensor (NIP @ CsPbBr)₃QDs) were dispersed in methylene chloride to a concentration of 5 × 10^-6g/mL solution, under the condition of 25 ℃, fully interacting with 300ng/mL Omethoate (OMT) for 30 minutes, and testing MIP @ CsPbBr before and after the action with the Omethoate (OMT) by using a fluorescence spectrometer₃QDs and corresponding NIP @ CsPbBr₃Fluorescence intensity of QDs at 510 nm. Specific recognition ability of imprinted polymers was evaluated by Imprinted Factor (IF).

TABLE 1 optimization of template molecule to functional monomer ratio

The specific test results are shown in FIG. 3. As can be seen from FIG. 3, as the amount of APTES added increases, the IF value increases and then decreases. The molar ratio of template to functional monomer is 1: 1 or 1: 2, providing a lower combinatorial capacity due to the low number of recognition sites for the target analyte. The highest combined capacity was obtained at a template to functional monomer molar ratio of 1:3, corresponding to an IF of 3.16. Therefore, the preferred molar volume ratio of the template molecule omethoate to the APTES is 1: (3-5), and the most preferred molar volume ratio of the template molecule omethoate to the APTES is 1: 3.

Structural characterization test example 1:APTES-blocked CsPbBr₃Structural characterization of perovskite quantum dots

The test method comprises the following steps: the APTES capped CsPbBr prepared in the first step of example 1 was taken₃Measuring an ultraviolet-visible (UV-vis) absorption spectrum of the perovskite quantum dot solution; absolute PL quantum yield (PLQY) was measured with PL excitation at 365 nm; the energy dispersive X-ray (EDX) spectrum is measured. The test results are shown in FIGS. 4-6.

FIG. 4 is APTES capped CsPbBr₃UV-vis absorption and PL emission spectra of quantum dot solutions. As can be seen from FIG. 4, CsPbBr was blocked at APTES₃A narrow green emission peak at 512nm was observed on the quantum dots; the green emission has a full width at half maximum (fwhm) of 34 nm.

FIG. 5 is APTES capped CsPbBr₃Time-resolved PL decay spectrum of quantum dots under 365nm excitation. As can be seen in FIG. 5, APTES-capped CsPbBr₃The absolute PL quantum yield (PLQY) of quantum dots was measured with 365nm excitation, yielding high values up to 92%, well above about 54% of the representative organic dye rhodamine 6G and about 65% of CdSe/CdS-ZnS. Transient studies indicate CsPbBr₃The high PLQY of quantum dots may be due to negligible electron hole trapping pathways. It is noteworthy that these intermediate gap states are the main cause of low PLQY for conventional quantum dots. The PL decay curve can be well fitted to a double exponential decay function, and the average PL decay life of the APTES end-capped CsPbBr3 quantum dot is measured to be 62.3ns, which is similar to other perovskite quantum dots.

FIG. 6 is APTES capped CsPbBr₃Energy dispersive X-ray (EDX) spectrograms of quantum dots. From fig. 6, Cs, Pb, Br and Si, N, 0 elements can be seen, demonstrating that quantum dots are successfully encapsulated in a silica matrix.

Structural characterization test example 2:FT-IR characterization

Separately detect CsPbBr₃Quantum dots (CsPbBr)₃QDs), APTES capped CsPbBr₃Quantum dots (APTES-capped CsPbBr)₃ QDs)、CsPbBr₃Perovskite quantum dot-molecular imprintingTrace fluorescence sensor (MIP @ CsPbBr)₃QDs).

The test method comprises the following steps: dried 100mg potassium bromide and 1mg CsPbBr prepared in the first step of comparative example 1 were weighed separately₃Quantum dots, APTES capped CsPbBr prepared in example 1₃Quantum dots, CsPbBr₃Perovskite quantum dot-molecular imprinting fluorescence sensor (MIP @ CsPbBr)₃QDs), mixing well in a dry agate mortar and grinding to a fine powder, tabletting. After deducting the potassium bromide background, three materials are respectively detected at 4000cm^-1-400cm^-1Light transmittance within the range. And (4) putting the sample into a Fourier infrared transform spectrometer for scanning to obtain an infrared spectrogram (figure 7).

As can be seen from FIG. 7, (a), (b) and (c) are CsPbBr, respectively₃Quantum dots (CsPbBr)₃QDs), APTES capped CsPbBr₃Quantum dots (APTES-capped CsPbBr)₃ QDs)、CsPbBr₃Perovskite quantum dot-molecular imprinting fluorescence sensor (MIP @ CsPbBr)₃QDs). In (a), 1716cm^-1A characteristic peak at (c), which corresponds to CO stretching vibration of the carboxyl group. Compared with the infrared data of the CsPbBr3 quantum dot, the infrared spectrum (b) of the APTES capped CsPbBr3 quantum dot is 1074cm^-1SiOSi asymmetric stretching at and 1640cm corresponding to NH^-1Stretching of the amino group at the characteristic peak of the absorption band of (1), and at 947cm^-1The Si — OH band of (a) is a weak band, which is the hydrolytic condensation of APTES and verifies the formation of a crosslinked organosilica network. CsPbBr₃Perovskite quantum dot-molecular imprinting fluorescence sensor (MIP @ CsPbBr)₃QDs) similar to the APTES capped CsPbBr3 quantum dots, indicating 1080cm^-1The absorption peak is attributed to the asymmetric expansion of SiOSi, and the SiO vibration band is 454cm^-1And 790cm^-1At 3321cm^-1The absorption peak at (a) is due to OH stretching. The infrared absorption from (c) indicates that the polymer layer was successfully synthesized.

Structural characterization test example 3:fluorescence excitation/emission spectroscopy

Detection of CsPbBr₃Perovskite quantum dot-molecular imprintingFluorescence sensor (MIP @ CsPbBr)₃QDs) and CsPbBr₃Perovskite quantum dot-molecular non-imprinted fluorescence sensor (NIP @ CsPbBr)₃QDs) (fig. 8).

The test method comprises the following steps:

1. 2mL of CsPbBr prepared in control example 1 was aspirated₃Perovskite quantum dot-molecular non-imprinted fluorescence sensor (NIP @ CsPbBr)₃QDs) into a fluorescence cuvette, a fixed fluorescence spectrometer emits excitation light at 365nm, and scans the emission spectrum of the double-bond quantum dot in the range of 380-600nm (fig. 8 (a)).

2. 2mL of CsPbBr prepared in example 1 was aspirated₃Perovskite quantum dot-molecular imprinting fluorescence sensor (MIP @ CsPbBr)₃QDs) into a fluorescence cuvette, a fixed fluorescence spectrometer emits excitation light at 365nm, and scans the emission spectrum of the double-bond quantum dot in the range of 380-600nm (fig. 8 (b)).

3.2 mL of CsPbBr from the unwashed template molecular Deoxyrogue (OMT) prepared in example 1 was aspirated₃Perovskite quantum dot-molecularly imprinted polymer, to a fluorescence cuvette, fixing a fluorescence spectrometer to emit excitation light of 365nm, and scanning the emission spectrum of the double-bond quantum dot in the range of 380-600nm (figure 8 (c)).

As can be seen in FIG. 8, CsPbBr of unwashed template molecularly deoxidized dimethoate (OMT)₃The fluorescence intensity of the perovskite quantum dot-molecularly imprinted polymer is relatively weak (fig. 8 (c)); however, after removal of the template molecule, CsPbBr₃Perovskite quantum dot-molecular imprinting fluorescence sensor (MIP @ CsPbBr)₃QDs) was remarkably recovered (FIG. 8(b)), and the fluorescence intensity was recovered to CsPbBr₃The perovskite quantum dot-molecular non-imprinted fluorescent sensor has almost the same value (fig. 8 (a)). These results indicate that the template molecule is almost completely removed from MIP @ CsPbBr₃Removal in the recognition chamber in QDs; in addition, the fluorescence signal is obvious, indicating MIP @ CsPbBr₃The size of QDs isIs uniform.

Structural characterization test example 4:characterization of XRD

The test method comprises the following steps: pure silica, APTES capped CsPbBr prepared in example 1₃Quantum dots (APTES-capped CsPbBr)₃ QDs)、CsPbBr₃Perovskite quantum dot-molecular imprinting fluorescence sensor (MIP @ CsPbBr)₃QDs) was ground into a uniform powder, loaded into a glass sample stage by means of tabletting, and the sample was irradiated with X-rays generated from a copper target to collect diffraction signals of the sample. The characterization results are shown in FIG. 9.

As can be seen in FIG. 9, (a), (b) and (c) are pure silica, APTES capped CsPbBr, respectively₃Quantum dots (APTES-capped CsPbBr)₃ QDs)、CsPbBr₃Perovskite quantum dot-molecular imprinting fluorescence sensor (MIP @ CsPbBr)₃QDs) X-ray diffraction (XRD) patterns. Pure silica (fig. 9(a)) has a broad peak at 2 θ of 20 ° to 25 °, and its amorphous structure is similar to other reports. APTES-blocked CsPbBr₃Quantum dots (APTES-capped CsPbBr)₃QDs) (FIG. 9(b)) and CsPbBr₃Perovskite quantum dot-molecular imprinting fluorescence sensor (MIP @ CsPbBr)₃QDs) (fig. 9(c)) showed that the (100), (110), (200), (211) peaks have cubic structures (or zincblende) and (220) shelves. MIP @ CsPbBr₃The diffraction peak intensity of QDs is weaker than that of APTES-trapped CsPbBr₃QDs, as can be explained in MIP @ CsPbBr₃The presence of the ratio APTES-capped CsPbBr in QDs₃QDs are more amorphous materials (silicon dioxide).

Structural characterization test example 4:transmission Electron microscopy characterization (TEM)

Separately detect CsPbBr₃Quantum dots (CsPbBr)₃QDs), APTES capped CsPbBr₃Quantum dots (APTES-capped CsPbBr)₃ QDs)、CsPbBr₃Perovskite quantum dot-molecular imprinting fluorescence sensor (MIP @ CsPbBr)₃QDs) Transmission Electron microscopy characterization (TEM)

The test method comprises the following steps: a small amount of CsPbBr prepared in step one of comparative example 1 was taken₃Quantum dots, APTES capped CsPbBr prepared in example 1₃Quantum dots, CsPbBr₃Perovskite quantum dotsMolecular imprinting fluorescence sensor (MIP @ CsPbBr)₃QDs) was dispersed in n-hexane and ultrasonically dispersed for 15 minutes. Absorbing a small amount of liquid sample, dripping the liquid sample on an ultrathin carbon film copper net, drying, and respectively CsPbBr₃Quantum dot and APTES-terminated CsPbBr₃Quantum dots, CsPbBr₃And (3) amplifying and photographing the perovskite quantum dot-molecular imprinting fluorescence sensor. FIG. 10(a) shows CsPbBr₃FIG. 10(b) is a graph showing the results of transmission electron microscopy characterization of quantum dots, CsPbBr₃High resolution projection electron microscopy characterization of the Quantum dots Structure, FIG. 10(c) APTES blocked CsPbBr₃FIG. 10(d) is a graph showing the results of transmission electron microscopy characterization of quantum dots, CsPbBr₃And (3) a transmission electron microscope characterization result graph of the perovskite quantum dot-molecular imprinting fluorescence sensor.

As can be seen from fig. 10(a) and (b), the quantum dots have good dispersibility, and the particle diameter is between 8 and 16 nm. As can be seen from FIG. 10(c), the APTES-capped CsPbBr₃Quantum dots, after hydrolysis, the original quantum dots are aggregated and embedded in SiO₂In the material, the APTES-terminated CsPbBr₃The particle diameter of the quantum dot is 30 nm. As can be seen from FIG. 10(d), CsPbBr₃Perovskite quantum dot-molecular imprinting fluorescence sensor (MIP @ CsPbBr)₃QDs) increased significantly to 200nm, indicating MIP @ CsPbBr₃QDs have large surface areas and efficient imprinting sites to bind template molecules.

Test conditions test example 1:MIP@CsPbBr₃kinetics of adsorption of QDs to Omethoate (OMT)

The test method comprises the following steps: the MIP @ CsPbBr prepared in example 1 was taken₃QDs and NIP @ CsPbBr prepared in control example 1₃QDs are respectively dispersed in dichloromethane to be prepared into a mass concentration of 5 × 10^-6Mixing the g/mL solution with 300ng/mL Omethoate (OMT), water bathing at 25 deg.C, and testing for different time (0, 5, 10, 15, 20, 25, 30, 40, 50, 60min), MIP @ CsPbBr₃QDs and NIP @ CsPbBr₃Fluorescence intensity of QDs at 510 nm. The adsorption kinetics of both complexes were explored and the results are shown in figure 11.

As can be seen in FIG. 11, the value at NIP @ CsPbBr₃After omethoate was added to the QDs, the fluorescence intensity remained constant after 15 minutes, indicating omethoate and NIP @ CsPbBr₃Lack of specific binding between QDs. In contrast, MIP @ CsPbBr₃The intensity of QDs decreases at a faster rate and reaches a constant value after 30 minutes. The constant intensity value indicates an equilibrium state when the adsorption and desorption rates are equal. Therefore, a preferred incubation time is 30 minutes. MIP @ CsPbBr₃QDs and NIP @ CsPbBr₃The different absorption kinetics of QDs for omethoate can be attributed to the blotting process.

Test conditions test example 2:temperature vs. MIP @ CsPbBr₃QDs measurement of Effect of omethoate

The test method comprises the following steps: the MIP @ CsPbBr prepared in example 1 was taken₃QDs and NIP @ CsPbBr prepared in control example 1₃QDs are respectively dispersed in dichloromethane to be prepared into a mass concentration of 5 × 10^-6g/ml solution, separately taking MIP @ CsPbBr prepared in example 1₃QDs are dispersed in methylene chloride to a mass concentration of 5X 10^-6Mixing the g/mL solution with 300ng/mL Omethoate (OMT), sequentially placing in water bath at 15 deg.C, 20 deg.C, 25 deg.C, 30 deg.C, 35 deg.C, 40 deg.C, 45 deg.C, 50 deg.C, 55 deg.C and 60 deg.C, standing for 30min, and testing MIP @ CsPbBr₃ QDs、NIP@CsPbBr₃QDs and Omethoate (OMT) -binding MIP @ CsPbBr₃Fluorescence intensity of QDs at 510 nm. The test results are shown in FIG. 12.

Fluorescence test conditions: the same conditions as those of the fluorescence test in test example 1 were used.

As can be seen from FIG. 12, NIP @ CsPbBr₃QDs and MIP @ CsPbBr₃The change of fluorescence intensity of QDs after adsorption of Omethoate (OMT) with temperature. NIP @ CsPbBr₃QDs and MIP @ CsPbBr₃QDs show strong fluorescence intensity at lower temperature and stable fluorescence at 15-30 deg.CThe light quenching rate. In order to obtain stable fluorescence intensity and high sensitivity, the temperature condition is easier to realize when the temperature is 25 ℃ and is normal temperature. Therefore, the preferred detection temperature is 25 ℃.

Test conditions test example 3:effect of solvent on MIP @ CsPbBr3 QDs recognition Performance

The test method comprises the following steps: MIP @ CsPbBr prepared in example 1₃QDs are dispersed in different solvents respectively to be configured into a mass concentration of 5 × 10^-6g/ml solution. Test MIP @ CsPbBr₃Fluorescence intensity at 510nm for QDs. The test results are shown in FIG. 13.

Different solvents: hexane, toluene, dichloromethane, ethyl acetate, chloroform, acetonitrile, N-dimethyl formamide (DMF) and ethanol.

FIG. 13(a) is a graph showing the effect of different polar organic solvent on the optical properties of MIP @ CsPbBr3 quantum dot composite; FIG. 13(b) MIP @ CsPbBr₃QDs is the fluorescence spectrum in different polar organic solutions. As can be seen from FIG. 13, MIP @ CsPbBr₃Bright solutions of QDs in low polarity solvents (i.e., hexane, toluene and dichloromethane) exhibit characteristic absorption and emission peaks resulting from localization; however, compared to chalcogenide quantum dots, MIP @ CsPbBr₃QDs are unstable in many common solvents, particularly in polar solvents (i.e., DMF and ethanol), because they are fully ionic crystals. The preferred detection solvent is methylene chloride, taking into account the toxicity of toluene and the subsequent sample extraction process.

Effect test example 1：MIP@CsPbBr₃Fluorescence sensing of Omethoate (OMT) by QDs

To evaluate MIP @ CsPbBr₃Fluorescence sensing of Omethoate (OMT) by QDs, separately determining MIP @ CsPbBr₃QDs and NIP @ CsPbBr₃Fluorescence response of QDs to various concentrations of Omethoate (OMT).

The test method comprises the following steps: MIP @ CsPbBr prepared in example 1₃QDs and NIP @ Cs prepared in control 1PbBr₃QDs are respectively dispersed in dichloromethane to be prepared into 5 multiplied by 10 mass concentration^-6The g/ml solution is mixed with Omethoate (OMT) solutions with different concentrations respectively, reacted for 30 minutes at the temperature of 25 ℃, and the fluorescence intensity of the solution at the position of 380-600nm is tested. The test results are shown in FIGS. 14-17.

The mass concentrations of the omethoate (0MT) solution are respectively as follows: 0ng/mL, 50ng/mL, 100ng/mL, 150ng/mL, 200ng/mL, 250ng/mL, 300ng/mL, 350ng/mL, 400 ng/mL.

As can be seen from FIGS. 14-15, MIP @ CsPbBr₃QDs and NIP @ CsPbBr₃QDs all exhibit a spectral response to the template molecule. However, with MIP @ CsPbBr₃More pronounced fluorescence quenching was NIP @ CsPbBr compared to QDs₃ QDs；MIP@CsPbBr₃Quenching efficiency or sensitivity of QDs is higher due to MIP @ CsPbBr₃The imprinting cavities are present in QDs and have a specific binding affinity for omethoate.

The fluorescence quenching system conforms to the Stern-Volmer equation in a certain concentration range, namely (F)₀-F)/F＝K_svc_q， c_qIs the concentration of the quencher, K_svAre constants of the Stern-Volmer equation. As can be seen from FIGS. 16-17, (F)₀/F-1) and MIP @ CsPbBr₃QDs and NIP @ CsPbBr₃Concentration of quencher for QDs (c)_q) All have good linear relationship. Calculated to obtain MIP @ CsPbBr₃The quenching equation for QDs is a linear equation: (F)₀-F)/F＝0.0016c-0.0082 (R²0.997) at Omethoate (OMT) concentrations ranging from 50 to 400 ng/mL; the quenching equation for NIP @ CsPbBr3 QDs is a linear equation: (F)₀-F)/F＝0.0005c-0.0082(R²＝0.991)

The assay also calculates the detection limit according to the 3 σ IUPAC criterion (3 σ/S), where σ is the standard deviation of the blank signal and S is the slope of the linear calibration, calculating MIP @ CsPbBr₃The Omethoate (OMT) detection limit of QDs is 18.8 ng/mL. In addition, the precision of 9 replicates of 300ng/mL Omethoate (OMT) was 1.7% (RSD). Under the optimal condition, the IF is 3.2, which shows that the imprinting process can greatly improve MIP @ CsPbBr₃Quenching efficiency of QDs for fluorescence of template molecules.

Effect test example 2：MIP@CsPbBr₃Selectivity of QDs

Organophosphorus insecticides such as dimethoate, dichlorvos and phoxim are selected as analogues of the template molecule Omethoate (OMT) to examine MIP @ CsPbBr₃Selectivity of QDs.

The test method comprises the following steps: the MIP @ CsPbBr prepared in example 1 was taken₃QDs and NIP @ CsPbBr prepared in control example 1₃QDs dispersed dichloromethane was prepared as a solution with a mass concentration of 100mg/L, mixed with 0.3. mu.g/mL omethoate, dimethoate, dichlorvos and phoxim, respectively, and subjected to a sufficient interaction at 25 ℃ for 30 minutes to measure the fluorescence intensity at 510 nm. The selectivity factor (γ) was used to evaluate the selectivity of the composite material, calculated from the formula: γ ═ Δ Ftemplate/Δ Fanalog, where Δ Ftemplate and Δ Fanalog are MIP @ CsPbBr₃QDs or NIP @ CsPbBr₃In the QDs complexed analyte, the more the gamma value is close to 1.00, the higher the selectivity of the material to the template. The test results are shown in FIG. 18 and Table 2.

TABLE 2 MIP @ CsPbBr₃QDs and NIP @ CsPbBr₃Selectivity factors for QDs

	ΔF_analytes(MIP)	γ_MIP	ΔF_analytes(NIP)	γ_NIP
					Omethoate	490	1.00	197	1.00
Leguo (fruit of musical instruments)	422	1.16	180	1.09
					Dichlorvos	205	2.39	189	1.04
Phoxim	200	2.46	196	1.01

As can be seen from FIG. 18 and Table 2, MIP @ CsPbBr3 QDs reacted most strongly to OMT in all the organophosphorus pesticides selected. This result indicates that MIP @ CsPbBr3 QDs have higher specificity for OMT because of their size, shapeAnd chemical group, the custom imprinted cavity is complementary to the OMT. Because the structure of Dimethoate is closest to the template in the template, Dimethoate's MIP @ CsPbBr3 QDs show an excellent selectivity factor of 1.16 in the analogs, closest to 1.00, indicating that a portion of Dimethoate can enter the imprinted cavity of the OMT. Further, MIP @ CsPbBr₃QDs and NIP @ CsPbBr₃QDs are less reactive towards dichlorvos and phoxim. Compared with OMT, other pesticides have different structures and cannot enter MIP @ CsPbBr₃Identification cavities of QDs. Thus, the relatively weak reaction is due to non-specific adsorption. Furthermore, NIP @ CsPbBr₃The selectivity factor of QDs for template and all analogues was close to 1.00, indicating NIP @ CsPbBr₃QDs are not selective for analogs and templates. The results show that MIP @ CsPbBr₃QDs are specific for Omethoate (OMT).

Effect test example 3:actual sample detection

To investigate MIP @ CsPbBr of the present invention₃Whether QDs can be used in real samples or not was examined for the amount of omethoate remaining in commercially available cabbage. No target analyte was found in the sample after the sample extraction procedure. Therefore, the recovery test using the spiked samples was used for the evaluation. Further, MIP @ CsPbBr₃The utility of QDs depends largely on the direct detection of ultra-trace OMT residues in agricultural products.

The test method comprises the following steps:

1. adding Omethoate (OMT) 50, 150, 300ng/mL into the extract to obtain samples with low, medium and high addition concentrations; then, MIP @ CsPbBr prepared in example 1 was taken₃QDs are dispersed in methylene chloride to a mass concentration of 5X 10^-6g/ml of the solution, mixed with the sample solution, interacted well for 30 minutes at 25 ℃ and tested for fluorescence intensity at 510 nm. Recovery corresponding to low, medium and high addition concentrations was carried out three times respectively. The test results are shown in Table 3.

2. The 40% Omethoate (OMT) pesticide was diluted 1000 times and then sprayed on the cabbage with an atomizer. After sample extraction procedure, MIP @ CsPbBr was used₃QDs detecting cabbage spraysOmethoate residual after 1 day, 7 days and 15 days. The test results are shown in Table 4.

Table 3 recovery and RSD values for spiked vegetable samples (n ═ 3)

As can be seen from Table 3, the recovery of the spiked vegetable samples ranged from 96.7 to 101% with a relative standard deviation of less than 4.21%. The results show that MIP @ CsPbBr₃The QDs has reliability and practicability for analyzing the pesticide in the standard sample, and has higher accuracy and repeatability.

Table 4 OMT remains in sprayed cabbage

As can be seen from Table 4, the OMT residues after 1 day, 7 days and 15 days of spraying were 0.30, 0.05 and 0.012 mg/kg, respectively, with a Relative Standard Deviation (RSD) of 3.35% -4.81%. The OMT residue after 15 days is lower than the Maximum Residue Limit (MRL) of vegetables allowed by GB 2763-2016 (national food safety standard, "maximum residue limit in pesticide food") by 0.02 mg/kg. Thus, MIP @ CsPbBr₃The sensitivity of QDs can meet the requirement of direct detection of OMT residues in agricultural products.

Effect test example 4:detection limit compared with the prior art

The detection limit is compared with other methods for detecting omethoate in the prior art, and the result is shown in a table 5.

TABLE 5 detection limit comparison

As can be seen from Table 5, CsPbBr of the present invention₃The perovskite quantum dot-molecular imprinting fluorescence sensor has the advantages of lowest detection limit, high sensitivity and good selectivity.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, so that any simple modification, equivalent change and modification made to the above embodiment according to the technical spirit of the present invention will still fall within the scope of the technical solution of the present invention without departing from the content of the technical solution of the present invention.

Claims

1. CsPbBr for detecting omethoate₃The preparation method of the perovskite quantum dot-molecular imprinting fluorescence sensor is characterized by comprising the following steps:

s1: preparation of APTES-capped CsPbBr₃Perovskite quantum dots

Adding 3-aminopropyltriethoxysilane into cesium carbonate, octadecene and PbBr₂Stirring in the mixture of oleic acid and oleylamine for 3 hours at 20 ℃ and 40% humidity in the presence of air, hydrolyzing, and purifying to obtain the APTES-terminated CsPbBr₃Perovskite quantum dots;

Oxidizing the template molecule with dimethoate, octadecene and the APTES-terminated CsPbBr obtained in the step S1₃Mixing and stirring the perovskite quantum dots and the residual 3-aminopropyltriethoxysilane after the reaction in the step S1 for 30 minutes, adding a cross-linking agent, and stirring for 12 hours to obtain CsPbBr₃Perovskite quantum dots-molecularly imprinted polymers;

s3: elution template molecular oxidation dimethoate

CsPbBr obtained in step S2₃Centrifuging the perovskite quantum dot-molecularly imprinted polymer, removing supernatant, removing template molecule with eluent to oxidize dimethoate, and obtaining CsPbBr₃Perovskite quantum dots-molecularly imprinted fluorescent sensors;

the step S1 includes:

2) octadecene and PbBr₂Mixing, vacuum degassing for 10 min, vacuum drying at 120 deg.C for 1 hr, introducing nitrogen gas, adding oleic acid, oleylamine and 3-aminopropyltriethoxysilane, clarifying, and heating to 160 deg.C;

4) centrifuging at 5000rpm for 10 min, washing with hexane for 2 times to obtain APTES-capped CsPbBr₃Perovskite quantum dots;

in the step 1), the molar volume ratio of the cesium carbonate to the oleic acid and the octadecene is 1mmol (1.0-1.1) ml: (12.0-12.3) ml;

in step 2), the PbBr is₂And octadecene, oleic acid, oleylamine, 3-aminopropyltriethoxysilane in a molar volume ratio of 0.376 mmol: 10 ml: 0.1 ml: 0.1 ml:1 ml;

in step 3), the cesium oleate solution and PbBr₂The molar volume ratio of (2-3) ml to 1 mmol;

in step S2, the molar volume ratio of the template molecule omethoate to octadecene is 1 mol: (8-12) L; the template molecule omethoate and APTES capped CsPbBr₃The molar ratio of the perovskite quantum dots is 1: (1X 10)^-6-3×10^-6)；

In step S2, the mole ratio of the template molecule omethoate to the rest of the 3-aminopropyl triethoxysilane in the reaction is 1 (3-5);

in step S2, the cross-linking agent is tetramethyl orthosilicate, and the molar volume ratio of the template molecule omethoate to the tetramethyl orthosilicate is 1 mol: (75-125) ml.

2. The method of claim 1, wherein: in step S3, the eluent is a mixture of hexane and ethyl acetate, and the volume ratio of hexane to ethyl acetate is 1: 3.

3. CsPbBr for detecting omethoate₃The perovskite quantum dot-molecular imprinting fluorescence sensor is characterized in that: the CsPbBr₃The perovskite quantum dot-molecular imprinting fluorescence sensor is prepared by the preparation method according to any one of claims 1-2.