Preparation method of perovskite quantum dot-molecular imprinting fluorescent composite material as well as obtained product and application of perovskite quantum dot-molecular imprinting fluorescent composite material

Abstract

The invention belongs to the technical field of fluorescent composite material preparation and food safety detection, and particularly relates to a preparation method of a perovskite quantum dot-molecular imprinting-based fluorescent composite material, an obtained product and application. The composite material is prepared by the following steps: firstly, preparing perovskite (CsPbBr3); then carrying out surface modification on the CsPbBr3; and finally, synthesizing CsPbBr3 (at) MIP. The material provided by the invention is simple in preparation method and good in stability, and the prepared composite material integrates the characteristics of a molecularly imprinted polymer and a fluorescent material and has the characteristics of high selectivity, high-sensitivity fluorescent response and the like to a target object. The material prepared by the invention can be directly used for detection and analysis of ciprofloxacin in aquatic products, and high-selectivity and high-sensitivity analysis and detection of ciprofloxacin in aquatic products are realized; the operation is simple and convenient, the detection period is short, and the detection time is greatly shortened; the method is high in detection sensitivity, and the minimum detection limit is 0.03 mg / L.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite material preparation and food safety detection, and specifically relates to a preparation method based on perovskite quantum dot-molecular imprinting fluorescent composite material and the obtained products and applications. Background Art

[0002] Ciprofloxacin is a synthetic third-generation quinolone antibiotic that is widely used in the prevention and treatment of animal diseases in livestock, poultry and aquaculture production due to its broad spectrum of antimicrobial activity and low side effects. However, long-term or excessive use of ciprofloxacin can lead to its accumulation in animal tissues. When they enter the food chain, ciprofloxacin can cause adverse reactions and increase drug resistance, especially affecting the nervous and sensory systems. Regarding the serious threat of ciprofloxacin to public health, people are increasingly concerned about ciprofloxacin residues in food, and strict regulatory limits have been established. Therefore, it is of great significance to develop a simple and sensitive method for monitoring ciprofloxacin residues in food or the environment.

[0003] At present, the main methods for the determination of ciprofloxacin include spectrophotometry, liquid chromatography (GB 5009.35-2016), capillary electrophoresis, liquid chromatography-mass spectrometry, etc. Although the above detection methods have greatly promoted the development of ciprofloxacin detection technology, these methods inevitably have disadvantages such as high cost and complex operation, which limits their practical application in routine analysis. Although some new sensor detection methods have high sensitivity, they have poor stability and selectivity. In the face of complex food matrices, it is particularly important to establish a detection method with low detection cost, strong selectivity, and time saving while ensuring detection sensitivity. Therefore, the preparation of a new type of highly selective and sensitive sensing material is the main purpose of current research. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a method for preparing a perovskite quantum dot-molecularly imprinted fluorescent composite material. The method improves the stability of the perovskite by coating a silicon dioxide-based molecularly imprinted layer on the surface of the perovskite, thereby solving the problems of poor stability and selectivity of the traditional ciprofloxacin detection method.

[0005] The present invention also provides a perovskite quantum dot-molecular imprinting fluorescent composite material prepared by the above preparation method.

[0006] Another object of the present invention is to provide an application of the above-mentioned perovskite quantum dot-molecular imprinting fluorescent composite material in the sensing detection of ciprofloxacin, and to establish a highly sensitive and highly selective detection technology for ciprofloxacin in food using a fluorescence spectrophotometer, thereby providing feasible ideas and technologies for the detection of harmful substances in food.

[0007] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: The present invention provides a method for preparing a perovskite quantum dot-molecular imprinting fluorescent composite material, comprising the following steps: (1) Preparation of perovskite (CsPbBr3) Lead bromide and tetra-n-octylammonium bromide are dissolved in toluene, stirred until clear, and a small amount of cesium carbonate n-octanoic acid solution is added dropwise. The solution immediately changes color to form a CsPbBr3 dispersion. (2) CsPbBr3 surface modification 3-aminopropyltriethoxysilane was added dropwise to the CsPbBr3 dispersion, stirred for a period of time to obtain CsPbBr3@SiO2 coated with silica, centrifuged and washed, and after washing, the supernatant was removed and vacuum dried overnight to obtain CsPbBr3@SiO2; (3) Synthesis of CsPbBr3@MIP The template molecule, the functional monomer and CsPbBr3@SiO2 are dispersed in anhydrous ethanol for prepolymerization; after the prepolymerization, a crosslinking agent is added and stirred in the dark; A mixed solution of glacial acetic acid and anhydrous ethanol was used as an eluent for elution, and the product was collected by centrifugation and vacuum dried to obtain a molecularly imprinted fluorescent composite material CsPbBr3@MIP.

[0008] Furthermore, in step (1), the concentration of the cesium carbonate n-octanoic acid solution is 0.03-0.05 g / 5 mL; the lead bromide and tetra-n-octylammonium bromide added to each 5 mL of toluene are 0.183 g and 0.547 g, respectively; and the volume ratio of n-octanoic acid to toluene is 1:1.

[0009] Furthermore, in step (2), the ratio of 3-aminopropyltriethoxysilane to cesium carbonate is 0.4 mL: 0.15-0.17 g; and the stirring time is 25-35 min.

[0010] Furthermore, in step (3), the molar ratio of the template molecule, the functional monomer and the cross-linking agent is 1:2-5:4-24, the template molecule is ciprofloxacin, the functional monomer is 3-aminopropyltriethoxysilane, and the cross-linking agent is tetramethoxysilane; the ratio of the template molecule to CsPbBr3@SiO2 is 1 mmol:30 mg.

[0011] Furthermore, the prepolymerization is carried out at 25° C. for 0.5 h; and the light-proof stirring time is 8 h.

[0012] Furthermore, in step (3), the volume ratio of glacial acetic acid to anhydrous ethanol is 1:4.

[0013] The present invention also provides a perovskite quantum dot-molecular imprinting fluorescent composite material prepared by the above preparation method.

[0014] The present invention further provides the use of the above-mentioned perovskite quantum dot-molecularly imprinted fluorescent composite material in the analysis and detection of ciprofloxacin, characterized in that it comprises the following steps: (1) Add CsPbBr3@MIP to the sample extract and shake at room temperature for analysis and detection.

[0015] (2) The sample to be tested is detected and analyzed using a fluorescence spectrophotometer.

[0016] Furthermore, in step (1), the solid-liquid ratio of the CsPbBr3@MIP to the sample extract is 2 mg:2 mL; and the room temperature oscillation time is 20 min.

[0017] Furthermore, in step (2), the conditions for the fluorescence spectrophotometer detection and analysis are: excitation wavelength of 365 nm, emission wavelength of 400-600 nm, gain of medium, and slit width of 5 nm.

[0018] The present invention adopts surface imprinting technology and prepares a perovskite molecular imprinting fluorescent composite material by adding silica-coated perovskite. On the one hand, the fluorescence characteristics of the fluorescent material are used to improve the sensitivity and stability of the material. On the other hand, the molecular imprinting material can improve the selectivity of the fluorescent material.

[0019] The beneficial effects of the present invention are: (1) The material preparation method provided by the present invention is simple and the synthesis environment is relatively friendly. The prepared composite material integrates the characteristics of molecular imprinting polymer and fluorescent material, and exhibits high selectivity and efficient fluorescence response to the target.

[0020] (2) The material prepared by the present invention can be directly used for the detection and analysis of ciprofloxacin in complex matrices, achieving highly selective and highly sensitive analytical detection of ciprofloxacin in food; the operation is simple and the detection cycle is short, which greatly shortens the detection time; the technical invention has a high detection sensitivity, and its minimum detection limit is 0.03 mg / L. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Transmission electron microscopy of CsPbBr3@MIP material; Figure 2 This is a scanning electron microscope image of CsPbBr3@MIP material; Figure 3 This is the infrared spectrum of CsPbBr3@MIP material; Figure 4The fluorescence selectivity of CsPbBr3@MIP material to ciprofloxacin; Figure 5 This is the standard curve of the fluorescence response of CsPbBr3@MIP to ciprofloxacin solution. DETAILED DESCRIPTION

[0022] In order to make the above features and advantages of the present invention clearer and easier to understand, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0023] Unless otherwise specified, the reagents involved in the following embodiments are commercially available and were not processed before use.

[0024] Example 1 The preparation method of the perovskite molecular imprinting fluorescent composite material comprises the following steps: (1) Dissolve 0.163 g of cesium carbonate solution in 5 mL of octanoic acid and stir magnetically until completely dissolved. Then, dissolve 0.183 g of lead bromide and 0.547 g of tetra-n-octylammonium bromide in 5 mL of toluene and stir until clear. Then, drop 0.5 mL of cesium carbonate solution in octanoic acid. The solution immediately changes color and CsPbBr3 is generated. (2) Add 0.4 mL of 3-aminopropyltriethoxysilane dropwise into the CsPbBr3 dispersion and stir for a while to obtain CsPbBr3@SiO2 coated with silica. After centrifugation, redisperse the mixture in n-hexane for washing. After washing, remove the supernatant and vacuum dry overnight.

[0025] (3) Disperse 1 mmol of ciprofloxacin, 3 mmol of 3-aminopropyltriethoxysilane and 30 mg of CsPbBr3@SiO2 in 15 mL of anhydrous ethanol and prepolymerize at 25 °C for 0.5 h. After the prepolymerization, add 8 mmol of tetramethoxysilane and stir in the dark for 8 h. A mixed solution of glacial acetic acid and anhydrous ethanol in a volume ratio of 1:4 was used as an eluent to remove the unreacted raw materials. The elution was performed 7 times, and the product was collected by centrifugation and vacuum dried to obtain the molecularly imprinted fluorescent composite material CsPbBr3@MIP. Without the template molecule ciprofloxacin, the above steps were repeated to obtain the fluorescent non-molecularly imprinted material (CsPbBr3@NIP).

[0026] Example 2 According to the method provided in Example 1, the ratio of the cross-linker to the template molecule (16:1) and the ratio of the functional monomer to the template molecule (3:1) were fixed respectively, and the dosage of the functional monomer and the cross-linker was optimized and analyzed. The ratio of the fluorescence quenching intensity of CsPbBr3@MIP and CsPbBr3@NIP by ciprofloxacin solution (imprinting factor) was used as the measurement index. The specific dosage relationship and imprinting factor are shown in Table 1.

[0027] Table 1 Optimization of functional monomer and cross-linking agent dosage Effect Example 1. Study on the properties of perovskite molecular imprinted fluorescent composites In order to further understand the properties of the prepared materials, the properties of the perovskite-based molecular imprinting fluorescent composite material prepared in Example 1 were studied.

[0028] Figure 1 This is a transmission electron microscope image of CsPbBr3@MIP material. As shown in the figure, CsPbBr3@MIP has an obvious molecular imprinting layer, proving that the imprinted material was successfully prepared.

[0029] Figure 2 This is a scanning electron microscope image of CsPbBr3@MIP material. As shown in the figure, CsPbBr3@MIP presents a regular spherical structure, proving that the imprinted material was successfully prepared.

[0030] Figure 3 This is the infrared spectrum of CsPbBr3@MIP material. The stretching vibration peak of Si-O-Si is located at 1056 cm -1 This indicates the presence of APTES and TMOS. -1 The characteristic peak at 2935 cm −1 Corresponding to the stretching vibration of CH, 1700 cm -1 The stretching vibration of NH is shown. These absorption peaks are consistent with those reported in the literature, indicating that CsPbBr3 and CsPbBr3@MIP have been successfully prepared.

[0031] Figure 4 This is the fluorescence selectivity experiment of CsPbBr3@MIP material to the same concentration of ciprofloxacin and its structural analogs enrofloxacin, ofloxacin, pefloxacin, norfloxacin, levofloxacin and fleroxacin. As shown in the figure, the fluorescence response of the material to the template molecule ciprofloxacin is significantly higher than that of its structural analogs, indicating that it has good fluorescence selectivity to ciprofloxacin.

[0032] Figure 5 Figure 2 is the standard curve of fluorescence response of CsPbBr3@MIP material to different concentrations of ciprofloxacin. As can be seen from the figure, with the increase of ciprofloxacin concentration, the fluorescence intensity of the material is quenched, and at 0.05 mg L -1 ~10 mg L -1 The minimum detection limit of this method was 0.03 mg L -1(S / N=3).

[0033] (II) Application of perovskite molecular imprinted fluorescent composite materials in the analysis and detection of ciprofloxacin The polymer CsPbBr3@MIP prepared in Example 1 was added to the sample extract at a solid-liquid ratio of 2 mg: 2 mL, and shaken at room temperature for 20 min before use for fluorescence spectrophotometer analysis. This method was applied to the determination of ciprofloxacin in actual samples and compared with the results of HPLC. The results are shown in Table 2. P ≥0.05, there was no significant difference in the results obtained by the two detection methods. Table 2 Application of CsPbBr3@MIP materials in fluorescence sensing of ciprofloxacin

Claims

1. A method for preparing a perovskite quantum dot-molecularly imprinted fluorescent composite material, characterized in that: The following steps are involved: (1) Preparation of perovskite (CsPbBr3) Lead bromide and tetra-n-octylammonium bromide are dissolved in toluene, stirred until clear, and a small amount of cesium carbonate n-octanoic acid solution is added dropwise. The solution immediately changes color to form a CsPbBr3 dispersion. (2) CsPbBr3 surface modification 3-aminopropyltriethoxysilane was added dropwise to the CsPbBr3 dispersion, stirred for a period of time to obtain CsPbBr3@SiO2 coated with silica, centrifuged and washed, and after washing, the supernatant was removed and vacuum dried overnight to obtain CsPbBr3@SiO2; (3) Synthesis of CsPbBr3@MIP The template molecule, the functional monomer and CsPbBr3@SiO2 are dispersed in anhydrous ethanol for prepolymerization; after the prepolymerization, a crosslinking agent is added and stirred in the dark; A mixed solution of glacial acetic acid and anhydrous ethanol was used as an eluent for elution, and the product was collected by centrifugation and vacuum dried to obtain a molecularly imprinted fluorescent composite material CsPbBr3@MIP.

2. The preparation method according to claim 1, characterized in that: In step (1), the concentration of the cesium carbonate n-octanoic acid solution is 0.03-0.05 g / 5 mL; the lead bromide and tetra-n-octylammonium bromide added to each 5 mL of toluene are 0.183 g and 0.547 g, respectively; and the volume ratio of n-octanoic acid to toluene is 1:

1.

3. The preparation method according to claim 1 or 2, characterized in that: In step (2), the ratio of 3-aminopropyltriethoxysilane to cesium carbonate is 0.4 mL: 0.15-0.17 g; and the stirring time is 25-35 min.

4. The preparation method according to any one of claims 1 to 3, characterized in that In step (3), the molar ratio of the template molecule, the functional monomer and the cross-linking agent is 1:2-5:4-24, the template molecule is ciprofloxacin, the functional monomer is 3-aminopropyltriethoxysilane, and the cross-linking agent is tetramethoxysilane; the ratio of the template molecule to CsPbBr3@SiO2 is 1 mmol:30 mg.

5. The preparation method according to claim 1 or 4 is characterized in that: The prepolymerization was carried out at 25° C. for 0.5 h, and the light-proof stirring time was 8 h.

6. The preparation method according to claim 1, 4 or 5, characterized in that: In step (3), the volume ratio of glacial acetic acid to anhydrous ethanol is 1:

4.

7. A perovskite quantum dot-molecular imprinting fluorescent composite material prepared by the preparation method according to any one of claims 1 to 6.

8. An application of the perovskite quantum dot-molecularly imprinted fluorescent composite material according to claim 7 in the analysis and detection of ciprofloxacin, characterized in that: The following steps are involved: (1) Add CsPbBr3@MIP to the sample extract and shake at room temperature for analysis and detection. (2) The sample to be tested is detected and analyzed using a fluorescence spectrophotometer.

9. The use according to claim 8, characterized in that: In step (1), the solid-liquid ratio of the CsPbBr3@MIP to the sample extract is 2 mg:2 mL; and the room temperature oscillation time is 20 min.

10. The use according to claim 8 or 9, characterized in that: In step (2), the conditions for the fluorescence spectrophotometer detection and analysis are: excitation wavelength of 365 nm, emission wavelength of 400-600 nm, gain of medium, and slit width of 5 nm.

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