UIO-66-NH2-based surface molecular imprinting fluorescence sensor, preparation method thereof and application of UIO-66-NH2-based surface molecular imprinting fluorescence sensor in detection of rhodamine 6G

Abstract

The invention discloses a surface molecular imprinting fluorescence sensor based on UIO-66-NH2, a preparation method of the surface molecular imprinting fluorescence sensor and application of the surface molecular imprinting fluorescence sensor in detection of rhodamine 6G, and relates to the field of surface molecular imprinting fluorescence sensors. The preparation method comprises the following steps: S1, dissolving UIO-66-NH2 in acetonitrile, adding warfarin and acrylic acid, and performing ultrasonic treatment to obtain a UIO-66-NH2 solution; adding ethylene glycol dimethacrylate and azodiisobutyronitrile, heating to 70-90 DEG C in an inert atmosphere, carrying out reflux reaction for 7-9 hours, and carrying out suction filtration and drying to obtain an intermediate; and S2, eluting warfarin in the intermediate, and drying to obtain the surface molecular imprinting fluorescence sensor. UIO-66-NH2 is adopted as a carrier and a fluorophore at the same time, the surface molecular imprinting fluorescence sensor capable of specifically recognizing and detecting rhodamine 6G is synthesized, and the surface molecular imprinting technology and the fluorescence sensing technology are combined, so that the capability of specifically recognizing rhodamine 6G of the surface molecular imprinting technology and the fluorescence sensing technology is kept; meanwhile, the advantages of high sensitivity and the like of the rhodamine 6G are fully exerted, so that the aim of trace detection of the rhodamine 6G is fulfilled.

Description

Technical Field

[0001] The invention relates to the field of surface molecular imprinting fluorescence sensors, in particular to a surface molecular imprinting fluorescence sensor based on UIO-66-NH2 and a preparation method thereof and application thereof in detecting rhodamine 6G. Background Art

[0002] Rhodamine 6G (Rh6G), also known as Rose Red 6G, is a water-soluble fluorescent dye with strong coloring ability. It has been widely used in food, textile dyeing, laser optics and plastic industry. However, studies have found that Rhodamine 6G has strong teratogenicity and carcinogenicity to the human body, and can cause a series of diseases such as the respiratory system, skin tissue, and nervous system, posing a certain threat to human life and health. Therefore, building a fast and efficient Rhodamine 6G detection technology is of great value to ensure food safety in my country.

[0003] At present, the detection methods for rhodamine pigments mainly include high performance liquid chromatography, liquid chromatography-tandem mass spectrometry, enhanced Raman scattering, etc. Although these methods are excellent in detection, there are some problems in practical application, such as cumbersome operating procedures, high detection costs, and time-consuming tests. Therefore, there is an urgent need to develop a rapid, sensitive and efficient detection method.

[0004] Molecularly imprinted fluorescent sensor is a fluorescent sensing material that introduces fluorescent response groups into molecularly imprinted polymers (MIPs). Compared with traditional molecularly imprinted polymers, surface molecularly imprinted polymers (SMIPs) are generated on the surface of solid substrates or close to their surface, providing more surface imprinting sites, accelerating the mass transfer rate, and greatly improving the adsorption capacity and adsorption efficiency. The surface molecularly imprinted fluorescent sensor prepared on the basis of SMIPs not only has the rapid and highly specific recognition ability of SMIPs, but also overcomes the defect of SMIPs itself that it is difficult to transmit signals, achieving the purpose of rapid and efficient detection of targets. However, there are few reports on the use of surface molecularly imprinted fluorescent sensors to detect rhodamine 6G. Summary of the invention

[0005] The present invention aims to provide a surface molecular imprinting fluorescence sensor based on UIO-66-NH2 and a preparation method thereof and an application thereof in detecting rhodamine 6G, so as to perform rapid, sensitive and efficient detection of rhodamine 6G.

[0006] In order to solve the above technical problems, the specific scheme adopted by the present invention is: a preparation method of a surface molecular imprinting fluorescence sensor based on UIO-66-NH2, comprising the following steps:

[0007] S1: Dissolve UIO-66-NH2 in acetonitrile and perform ultrasonic treatment, then add warfarin and acrylic acid and perform ultrasonic treatment again, finally add ethylene glycol dimethacrylate and azobisisobutyronitrile, heat to 70-90° C. under an inert atmosphere, reflux for 7-9 hours, filter, and dry to obtain an intermediate;

[0008] S2: using an eluent to elute the warfarin in the intermediate, and drying the eluted intermediate to obtain the surface molecular imprinting fluorescence sensor.

[0009] As a further optimization of the above technical solution: the preparation method of UIO-66-NH2 is as follows: zirconium chloride and 2-aminoterephthalic acid are dissolved in N,N-dimethylformamide aqueous solution, reacted at 110-130°C for 22-26h, centrifuged, washed, and dried to obtain UIO-66-NH2.

[0010] As a further optimization of the above technical solution: in step S1, the mass ratio of UIO-66-NH2 to warfarin is 2:1.4-1.6.

[0011] As a further optimization of the above technical solution: in step S2, the eluent is a mixture of methanol and acetic acid in a volume ratio of 4:1.

[0012] As a further optimization of the above technical solution: in step S2, the intermediate is placed in a Soxhlet extractor for elution at a temperature of 80-100°C.

[0013] As a further optimization of the above technical solution: Step S2 is specifically: using an eluent to elute the warfarin in the intermediate until no warfarin is detected in the supernatant, then eluting with pure methanol for 10-12 hours, and finally drying the eluted intermediate to obtain the surface molecular imprinting fluorescent sensor.

[0014] As a further optimization of the above technical solution: the drying temperature of step S2 is 55-65°C.

[0015] A surface molecular imprinting fluorescent sensor based on UIO-66-NH2 is prepared by any of the above methods. The surface molecular imprinting fluorescent sensor is UIO-66-NH2@Rh6G@SMIPs.

[0016] Application of a surface molecular imprinted fluorescence sensor based on UIO-66-NH2 in the detection of rhodamine 6G.

[0017] As a further optimization of the above technical solution: the detection environment is pH = 7.0.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention uses UIO-66-NH2 as both a carrier and a fluorescent group to synthesize a surface molecular imprinting fluorescent sensor that can specifically identify and detect rhodamine 6G. By combining the surface molecular imprinting technology with the fluorescent sensing technology, not only the ability of the former to specifically identify rhodamine 6G is maintained, but also the advantages of the latter such as high sensitivity are fully utilized to achieve the purpose of trace detection of rhodamine 6G. The surface molecular imprinting fluorescent sensor prepared by the present invention has the advantages of good optical stability, high sensitivity, strong specific adsorption ability and good anti-interference, and meets the needs of accurately detecting rhodamine 6G in complex actual samples. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Infrared spectra (A) and X-ray diffraction patterns (B) of UIO-66-NH2, UIO-66-NH2@Rh6G@SMIPs, UIO-66-NH2@Rh6G@SNIPs and Rh6G@MIPs;

[0021] Figure 2 For I 560 / I 440 pH change graph;

[0022] Figure 3 Fluorescence spectra and fluorescence photos of UIO-66-NH2@Rh6G@SMIPs (A) and UIO-66-NH2@Rh6G@SNIPs (B) after adsorption of rhodamine 6G, and their corresponding I 560 / I 440 Scatter plot (C);

[0023] Figure 4 The excitation spectrum (curve a), emission spectrum (curve b) of UIO-66-NH2@Rh6G@SMIPs and the excitation spectrum (curve c), emission spectrum (curve d) of Rhodamine 6G;

[0024] Figure 5 The dynamic adsorption curves of UIO-66-NH2@Rh6G@SMIPs and UIO-66-NH2@Rh6G@SNIPs for rhodamine 6G;

[0025] Figure 6 I after UIO-66-NH2@Rh6G@SMIPs adsorbed different pigments (A) and Rhodamine 6G+interfering pigment mixture (B) 560 / I 440 ;

[0026] Figure 7 I after adsorption of rhodamine 6G and interfering ions (A) and mixed solution of rhodamine 6G + interfering ions (B) by UIO-66-NH2@Rh6G@SMIPs 560 / I 440 ;

[0027] Figure 8 The stability of UIO-66-NH2@Rh6G@SMIPs;

[0028] Fig. 9 This is the working curve of UIO-66-NH2@Rh6G@SMIPs. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further elaborated in detail below in conjunction with specific embodiments. The parts of the present invention that are not described and disclosed in detail in the following embodiments should be understood as the prior art known or should be known to those skilled in the art.

[0030] The present invention discloses a method for preparing a surface molecular imprinting fluorescence sensor based on UIO-66-NH2, and the preparation method comprises the following steps:

[0031] S1: Dissolve UIO-66-NH2 in acetonitrile, add warfarin and acrylic acid (hereinafter referred to as AA), perform ultrasonic treatment, then add ethylene glycol dimethacrylate (hereinafter referred to as EGDMA) and azobisisobutyronitrile (hereinafter referred to as AIBN), stir, and finally heat to 70-90°C under an inert atmosphere for reflux reaction for 7-9h, filter, and dry to obtain an intermediate;

[0032] Among them, the mass ratio of UIO-66-NH2 and warfarin is 2:1.4-1.6; the inert atmosphere is N2 atmosphere; the preparation method of UIO-66-NH2 is as follows: zirconium chloride and 2-aminoterephthalic acid are dissolved in N,N-dimethylformamide (hereinafter referred to as: DMF) aqueous solution, and magnetically stirred at room temperature for 20 minutes to make it fully dissolved, and then the solution is transferred to a reactor, reacted at 110-130°C for 22-26h, centrifuged, and repeatedly washed with DMF and anhydrous ethanol twice, and finally, the product obtained by centrifugation is placed in a 60°C oven to dry to obtain UIO-66-NH2.

[0033] S2: Methanol and acetic acid are mixed to prepare an eluent, wherein the volume ratio of methanol to acetic acid in the eluent is 4:1; the eluent is used to elute the warfarin in the intermediate, and the eluted intermediate is dried to obtain the surface molecular imprinting fluorescent sensor. Specifically, the intermediate is placed in a Soxhlet extractor for elution, and the elution temperature is 80-100°C. When the eluent is used to elute the warfarin in the intermediate, when the warfarin is not detected in the supernatant, pure methanol is used for elution for 10-12h, and finally the eluted intermediate is dried in an oven at 55-65°C to obtain the surface molecular imprinting fluorescent sensor, which is UIO-66-NH2@Rh6G@SMIPs.

[0034] The present invention uses precipitation polymerization method and UIO-66-NH2 as both a carrier and a fluorescent group to prepare a surface molecular imprinting fluorescent sensor UIO-66-NH2@Rh6G@SMIPs that can specifically identify rhodamine 6G, which can be used to detect rhodamine 6G. In the actual detection, the preferred detection environment is pH=7.0.

[0035] Example 1 Preparation of UIO-66-NH2@Rh6G@SMIPs

[0036] 1. Weigh 0.9g zirconium chloride and 0.6996g 2-aminoterephthalic acid, put them into a mixed solution of 180mL DMF and 0.57mL ultrapure water, and stir them magnetically at room temperature for 20 minutes to fully dissolve them. Then transfer all the solutions to the reactor and react at 120°C for 24 hours. Then centrifuge the solution in the reactor and wash it repeatedly with DMF and anhydrous ethanol twice. Finally, place the product obtained by centrifugation in a 60°C oven to dry to obtain UIO-66-NH2;

[0037] 2. Weigh 0.2g UIO-66-NH2 and 125mL acetonitrile in a three-necked flask, and ultrasonicate for 10min to make the carrier fully and evenly dispersed in the solvent. Weigh 0.1542g warfarin and 255μL AA, and ultrasonicate for 30min to make the two prepolymerize on the surface of UIO-66-NH2, then add 3965μL EGDMA and 0.1267g AIBN, stir magnetically for 10min at room temperature, and heat under reflux at 80℃ under N2 protection for 8h, filter, discard the filtrate, take the filter residue, and dry the filter residue. The dried product is the intermediate;

[0038] A Soxhlet extraction apparatus was built, and the elution temperature was set to 90°C. The intermediate wrapped in filter paper was placed in the Soxhlet extractor, and warfarin was eluted with a mixed solution of methanol / acetic acid (v / v=4:1) until warfarin was not detected in the supernatant. Then, pure methanol was used for elution for 12 hours, and finally the product was dried in an oven at 60°C to obtain the product UIO-66-NH2@Rh6G@SMIPs.

[0039] Example 2 Preparation of UIO-66-NH2@Rh6G@SMIPs

[0040] 1. Weigh 0.9g zirconium chloride and 0.6996g 2-aminoterephthalic acid, put them into a mixed solution of 180mL DMF and 0.57mL ultrapure water, and stir them magnetically at room temperature for 20 minutes to fully dissolve them. Then transfer all the solution to the reactor and react at 130°C for 22 hours. Then centrifuge the solution in the reactor and wash it repeatedly with DMF and anhydrous ethanol twice. Finally, place the product obtained by centrifugation in a 60°C oven to dry to obtain UIO-66-NH2;

[0041] 2. Weigh 0.2g UIO-66-NH2 and 125mL acetonitrile in a three-necked flask, and ultrasonicate for 10min to make the carrier fully and evenly dispersed in the solvent. Weigh 0.16g warfarin and 255μL AA, and ultrasonicate for 30min to make the two prepolymerize on the surface of UIO-66-NH2, then add 3965μL EGDMA and 0.1267g AIBN, stir magnetically at room temperature for 10min, and heat under reflux at 85℃ under N2 protection for 7h, filter, discard the filtrate, take the filter residue, and dry the filter residue. The dried product is the intermediate;

[0042] A Soxhlet extraction apparatus was built, and the elution temperature was set to 85°C. The intermediate wrapped in filter paper was placed in the Soxhlet extractor, and warfarin was eluted with a mixed solution of methanol / acetic acid (v / v=4:1) until warfarin was not detected in the supernatant. Then, pure methanol was used for elution for 12 hours, and finally the product was dried in an oven at 65°C to obtain the product UIO-66-NH2@Rh6G@SMIPs.

[0043] Example 3 Preparation of UIO-66-NH2@Rh6G@SMIPs

[0044] 1. Weigh 0.9g zirconium chloride and 0.6996g 2-aminoterephthalic acid, put them into a mixed solution of 180mL DMF and 0.57mL ultrapure water, and stir them magnetically at room temperature for 20 minutes to fully dissolve them. Then transfer all the solution to the reactor and react at 110°C for 26 hours. Then centrifuge the solution in the reactor and wash it repeatedly with DMF and anhydrous ethanol twice. Finally, place the product obtained by centrifugation in a 60°C oven to dry to obtain UIO-66-NH2;

[0045] 2. Weigh 0.2g UIO-66-NH2 and 125mL acetonitrile in a three-necked flask, and ultrasonicate for 10min to make the carrier fully and evenly dispersed in the solvent. Weigh 0.14g warfarin and 255μL AA, and ultrasonicate for 30min to make the two prepolymerize on the surface of UIO-66-NH2, then add 3965μL EGDMA and 0.1267g AIBN, stir magnetically at room temperature for 10min, and heat under reflux at 75℃ under N2 protection for 9h, filter, discard the filtrate, take the filter residue, and dry the filter residue. The dried product is the intermediate;

[0046] A Soxhlet extraction apparatus was built, and the elution temperature was set to 95°C. The intermediate wrapped in filter paper was placed in the Soxhlet extractor, and warfarin was eluted with a mixed solution of methanol / acetic acid (v / v=4:1) until warfarin was not detected in the supernatant. Then, pure methanol was used for elution for 10 hours, and finally the product was dried in an oven at 55°C to obtain the product UIO-66-NH2@Rh6G@SMIPs.

[0047] Comparative Example 1 Preparation of UIO-66-NH2@Rh6G@SNIPs

[0048] The overall steps of this comparative example 1 are similar to those of Example 1, except that warfarin is not added, as follows:

[0049] 1. Weigh 0.9g zirconium chloride and 0.6996g 2-aminoterephthalic acid, put them into a mixed solution of 180mL DMF and 0.57mL ultrapure water, and stir magnetically at room temperature for 20 minutes to fully dissolve them. Then transfer all the solution to the reactor and react at 120°C for 24 hours. Then centrifuge the solution in the reactor and wash it repeatedly with DMF and anhydrous ethanol twice. Finally. Place the product obtained by centrifugation in a 60°C oven to dry to obtain UIO-66-NH2;

[0050] 2. Weigh 0.2g UIO-66-NH2 and 125mL acetonitrile in a three-necked flask, and ultrasonicate for 10min to make the carrier fully and evenly dispersed in the solvent. Weigh 255μL AA, add 3965μL EGDMA and 0.1267g AIBN, stir magnetically at room temperature for 10min, and heat under reflux at 80℃ and N2 protection for 8h. Discard the filtrate, take the filter residue, and dry the filter residue. The dried product is UIO-66-NH2@Rh6G@SNIPs.

[0051] Comparative Example 2 Preparation of Rh6G@MIPs

[0052] Take 125mL of acetonitrile in a three-necked flask, add 0.1542g of warfarin and 255μL of AA, ultrasonicate for 30min, then add 3965μL of EGDMA and 0.1267g of AIBN, stir magnetically at room temperature for 10min, heat under reflux at 80℃ under N2 protection for 8h, filter, discard the filtrate, take the filter residue, dry the filter residue, and the dried product is the intermediate;

[0053] A Soxhlet extraction apparatus was built, and the elution temperature was set to 90°C. The intermediate wrapped in filter paper was placed in the Soxhlet extractor, and warfarin was eluted with a mixed solution of methanol / acetic acid (v / v=4:1) until warfarin was not detected in the supernatant. Then, pure methanol was used for elution for 12 hours, and finally the product was dried in an oven at 60°C to obtain the product Rh6G@SMIPs.

[0054] Next, the performance of UIO-66-NH2@Rh6G@SMIPs prepared by the present invention is analyzed.

[0055] For ease of understanding, the raw materials used in the following experimental process are first described as follows: the following UIO-66-NH2@Rh6G@SMIPs is prepared in Example 1, UIO-66-NH2 is prepared by the method of step 1 in Example 1, UIO-66-NH2@Rh6G@SNIPs is prepared in Comparative Example 1, and Rh6G@MIPs is prepared in Comparative Example 2.

[0056] 1. Structural Characterization

[0057] <Infrared Spectroscopy Analysis>

[0058] Take UIO-66-NH2, UIO-66-NH2@Rh6G@SMIPs, UIO-66-NH2@Rh6G@SNIPs, and Rh6G@MIPs and place them in an infrared spectrophotometer respectively, adjust the pressure value to about 20, scan the infrared spectrum, and obtain the infrared spectrum (FT-IR spectrum).

[0059] The infrared spectra of UIO-66-NH2, UIO-66-NH2@Rh6G@SMIPs, UIO-66-NH2@Rh6G@SNIPs and Rh6G@MIPs are as follows Figure 1 as shown in -1 A. The absorption peaks at 667 cm -1 and 1571 cm -1 are the infrared characteristic peaks of UIO-66-NH2. Compared with the infrared spectrum of Rh6G@MIPs, these two characteristic peaks can be found in the infrared spectra of UIO-66-NH2@Rh6G@SMIPs and UIO-66-NH2@Rh6G@SNIPs, indicating that the polymer has been successfully synthesized onto UIO-66-NH2. At the same time, the absorption peaks at 2987 cm -1 for the C-H stretching vibration and C=O stretching vibration of AA and EGDMA can be found in UIO-66-NH2@Rh6G@SMIPs, UIO-66-NH2@Rh6G@SNIPs and Rh6G@MIPs, indicating that AA and EGDMA have been successfully polymerized into the polymer.

[0060] <X-ray Diffraction Analysis>

[0061] UIO-66-NH2, UIO-66-NH2@Rh6G@SMIPs, UIO-66-NH2@Rh6G@SNIPs and Rh6G@MIPs were ground, pressed into tablets, and finally loaded onto an X-ray diffractometer to scan the X-ray diffraction pattern (XRD pattern) under the conditions of a scanning speed of 10° min -1 and a scanning range of 5-90°.

[0062] The X-ray diffraction patterns of UIO-66-NH2, UIO-66-NH2@Rh6G@SMIPs, UIO-66-NH2@Rh6G@SNIPs and Rh6G@MIPs are as follows Figure 1 as shown in B. UIO-66-NH2 shows sharp characteristic peaks at diffraction angles 2θ = 7.34° and 8.4°, and a non-main peak appears near 2θ = 25.64°. These peaks can be found in both UIO-66-NH2@Rh6G@SMIPs and UIO-66-NH2@Rh6G@SNIPs, but not in Rh6G@MIPs, indicating that UIO-66-NH2@Rh6G@SMIPs and UIO-66-NH2@Rh6G@SNIPs have been successfully loaded onto UIO-66-NH2.

[0063] II. Adsorption Performance Test and Result Analysis

[0064] <pH Optimization>

[0065] In order to optimize the performance of UIO-66-NH2@Rh6G@SMIPs in detecting rhodamine 6G, this experiment focused on the pH value of the detection environment. pH value is one of the important indicators that affect the polymer adsorption target, which will affect the affinity of UIO-66-NH2@Rh6G@SMIPs for rhodamine 6G, so it is necessary to optimize the pH environment of its adsorption target.

[0066] Add NaH2PO4 and Na2HPO4 to a beaker to prepare a phosphate buffered saline (PBS buffer) with a pH of 7, and then add concentrated NaOH and concentrated HCl to prepare PBS buffers of different pH values. Use PBS buffers of different pH values ​​as solvents and prepare concentrations of 5 μmol·L -1 Rhodamine 6G solution. Rhodamine 6G solutions (6 mL) with different pH values ​​were mixed with 30 mg UIO-66-NH2@Rh6G@SMIPs, oscillated on an oscillator for 30 min, filtered, washed with distilled water, and the filter cakes were collected and dried naturally to measure their fluorescence spectra.

[0067] Figure 2 The fluorescence peak ratio I of UIO-66-NH2@Rh6G@SMIPs after adsorption of Rhodamine 6G under different pH conditions 560 / I 440 At pH = 7.0, I 560 / I 440 When pH < 7.0, as the pH decreases, I 560 / I 440 This may be due to the fact that H + The presence of I affects the imprinting sites of UIO-66-NH2@Rh6G@SMIPs and reduces its adsorption capacity for rhodamine 6G. When pH>7.0, I 560 / I 440 It also shows a gradually decreasing trend, which is due to the defects on the polymer surface under alkaline conditions, destroying the binding sites. Therefore, the detection environment of UIO-66-NH2@Rh6G@SMIPs was carried out under pH=7.0.

[0068] <Static adsorption curve measurement>

[0069] In order to explore the detection ability of UIO-66-NH2@Rh6G@SMIPs and UIO-66-NH2@Rh6G@SNIPs for rhodamine 6G in the experiment, samples with different concentrations of rhodamine 6G adsorbed were tested.

[0070] Rhodamine 6G solutions (6 mL) of different concentrations were mixed with 30 mg of UIO-66-NH2@Rh6G@SMIPs, respectively, oscillated on an oscillator for 30 min, filtered, washed with distilled water, and the filter cakes were collected and dried naturally, and their fluorescence spectra were measured.

[0071] The static adsorption curve of UIO-66-NH2@Rh6G@SNIPs was determined in accordance with the above experimental procedures.

[0072] like Figure 3 As shown in A, with the increase of rhodamine 6G concentration, the fluorescence peak at 440nm gradually decreased, while the fluorescence peak at 560nm gradually increased, and the fluorescence intensity showed a ratiometric change. At the same time, under ultraviolet light, the fluorescence color of UIO-66-NH2@Rh6G@SMIPs also changed visibly with the increase of rhodamine 6G, from the initial bright blue fluorescence to bright orange fluorescence.

[0073] Under the same conditions, the adsorption of different concentrations of rhodamine 6G by UIO-66-NH2@Rh6G@SNIPs was tested. Figure 3 As shown in B, UIO-66-NH2@Rh6G@SNIPs also has a fluorescence change trend similar to that of UIO-66-NH2@Rh6G@SMIPs. However, the increase in the fluorescence peak of UIO-66-NH2@Rh6G@SNIPs at 560 nm is not as significant as that of UIO-66-NH2@Rh6G@SMIPs.

[0074] like Figure 3 As shown in C, the I of UIO-66-NH2@Rh6G@SMIPs and UIO-66-NH2@Rh6G@SNIPs after adsorption of rhodamine 6G 560 / I 440 It can be found that the I 560 / I 440 Both gradually increased, but the increasing trend of UIO-66-NH2@Rh6G@SMIPs was higher than that of UIO-66-NH2@Rh6G@SNIPs. This is because UIO-66-NH2@Rh6G@SMIPs has a similar structural cavity to rhodamine 6G, which makes it have a stronger adsorption capacity for rhodamine 6G.

[0075] In order to explore the reason for the fluorescence change after UIO-66-NH2@Rh6G@SMIPs adsorbed rhodamine 6G, the excitation and emission spectra of UIO-66-NH2@Rh6G@SMIPs and rhodamine 6G were scanned. Figure 4It can be seen that the excitation spectra of UIO-66-NH2@Rh6G@SMIPs and rhodamine 6G overlap near 350nm. It can be inferred that the two will compete with each other for excitation light, resulting in the fluorescence peak of UIO-66-NH2@Rh6G@SMIPs at 440nm decreasing and the fluorescence peak at 560nm increasing as the concentration of rhodamine 6G increases.

[0076] <Dynamic adsorption curve measurement>

[0077] To further study whether UIO-66-NH2@Rh6G@SMIPs has a fast and efficient adsorption capacity for rhodamine 6G, UIO-66-NH2@Rh6G@SMIPs and UIO-66-NH2@Rh6G@SNIPs were allowed to adsorb the same concentration of rhodamine 6G at different times.

[0078] A certain concentration of rhodamine 6G solution (6 mL) was mixed with 30 mg of UIO-66-NH2@Rh6G@SMIPs, and the oscillation time was controlled to be 0, 3, 9, 18, 29, 37, 50, 80, 120, 180, 300, 500, and 600 s. The mixture was filtered, washed with distilled water, and the filter cake was collected and dried naturally, and its fluorescence spectrum was measured.

[0079] The dynamic adsorption curve of UIO-66-NH2@Rh6G@SNIPs was determined in accordance with the above experimental procedures.

[0080] like Figure 5 As shown, within 0-80 s, the I 560 / I 440 Both of them reached adsorption equilibrium at 300s and 500s, respectively. After adsorption saturation, the I 560 / I 440 The above results show that UIO-66-NH2@Rh6G@SMIPs has a faster adsorption rate and a larger adsorption amount.

[0081] <Optional Test>

[0082] To further confirm whether UIO-66-NH2@Rh6G@SMIPs has the ability to selectively adsorb rhodamine 6G, UIO-66-NH2@Rh6G@SMIPs was allowed to adsorb different pigments, rhodamine 6G + interfering pigments, different ions, and rhodamine 6G + interfering ion samples under the same conditions for comparison, and their fluorescence spectra were measured.

[0083] Take 6 mL of each sample with a concentration of 5 μmol·L -1 Rhodamine 6G, allura red, alizarin red, carmine, Sudan I, amaranth and acid fuchsin solutions and blank solution (PBS buffer) were mixed with 30 mg UIO-66-NH2@Rh6G@SMIPs, oscillated on an oscillator for 30 min, filtered, washed with distilled water, the filter cake was collected and dried naturally, and its fluorescence spectrum was measured.

[0084] To a conical flask containing 30 mg of UIO-66-NH2@Rh6G@SMIPs, 6 mL of 5 μmol·L -1 The mixtures of rhodamine 6G solution, rhodamine 6G+allura red, rhodamine 6G+alizarin red, rhodamine 6G+carmine, rhodamine 6G+Sudan I, rhodamine 6G+amaranth and rhodamine 6G+acid fuchsin (the concentration ratio of rhodamine 6G to pigment in the mixtures was 1:1) were oscillated on an oscillator for 30 minutes, filtered, washed with distilled water, the filter cakes were collected and dried naturally, and their fluorescence spectra were measured.

[0085] Take 6 mL of each sample with a concentration of 5 μmol·L -1 Rhodamine 6G solution, potassium persulfate, potassium carbonate, potassium bromide, potassium iodide, magnesium chloride, barium chloride, sodium chloride, calcium chloride and potassium chloride as well as blank solution (PBS buffer) were mixed with 30 mg UIO-66-NH2@Rh6G@SMIPs, oscillated on an oscillator for 30 min, filtered, washed with distilled water, the filter cake was collected and dried naturally, and its fluorescence spectrum was measured.

[0086] To a conical flask containing 30 mg of UIO-66-NH2@Rh6G@SMIPs, 6 mL of 5 μmol·L -1 The mixture of rhodamine 6G solution, rhodamine 6G + potassium persulfate, rhodamine 6G + potassium carbonate, rhodamine 6G + potassium bromide, rhodamine 6G + potassium iodide, rhodamine 6G + magnesium chloride, rhodamine 6G + barium chloride, rhodamine 6G + sodium chloride, rhodamine 6G + calcium chloride, and rhodamine 6G + potassium chloride (the concentration ratio of rhodamine 6G to interference in the mixture was 1:1) was oscillated on an oscillator for 30 minutes, filtered, washed with distilled water, the filter cake was collected and dried naturally, and its fluorescence spectrum was measured.

[0087] like Figure 6 As shown in A, UIO-66-NH2@Rh6G@SMIPs adsorbed rhodamine 6G. 560 / I 440 Moreover, after adsorbing a single rhodamine 6G solution and a mixed interfering pigment solution, its I 560 / I 440 Not much difference ( Figure 6 B).

[0088] like Figure 7 As shown in A, compared with the adsorption of other ions, the I 560 / I 440 When rhodamine 6G and different interfering ions were adsorbed simultaneously, the I 560 / I 440 The change value is similar to the result of adsorption of rhodamine 6G only ( Figure 7 B). The above results show that UIO-66-NH2@Rh6G@SMIPs has good specific adsorption ability and good anti-interference ability.

[0089] <Stability Performance Test>

[0090] PBS buffer (6 mL) and 5 μmol·L -1 Rhodamine 6G solution (6 mL) was added to a conical flask containing 30 mg UIO-66-NH2@Rh6G@SMIPs, oscillated on an oscillator for 30 min, filtered, washed with distilled water, and the filter cake was collected and dried naturally. The fluorescence spectrum was measured within 14 days. Under the same conditions, the above experiments were carried out in parallel in 3 groups.

[0091] The results are as follows Figure 8 As shown in the figure, the I 560 / I 440 No obvious changes occurred, indicating that it has good optical stability.

[0092] 3. Application in actual samples

[0093] <Working curve measurement>

[0094] To investigate the fluorescence response of UIO-66-NH2@Rh6G@SMIPs to different concentrations of rhodamine 6G, the concentration of rhodamine 6G was 0-10 μmol·L -1 Draw a working curve within the range.

[0095] Different concentrations of Rhodamine 6G solution (6 mL) were mixed with 30 mg UIO-66-NH2@Rh6G@SMIPs, shaken for 30 min, filtered, washed with distilled water, and the filter cake was collected and dried naturally to measure its fluorescence spectrum. Under the same conditions, the above experiments were carried out in parallel for 3 groups.

[0096] The results are as follows Fig. 9As shown, the fluorescence intensity ratio of UIO-66-NH2@Rh6G@SMIPs I 560 / I 440 With rhodamine 6G concentration in the range of 0-10 μmol·L -1 It shows a good linear relationship, and its linear equation is I 560 / I 440 =0.28992c+0.02187(R 2 =0.998). According to 3S b / m calculation (where S b is the standard deviation of 10 blank samples, m is the slope of the working curve), and the detection limit is 12.77nmol·L -1 .

[0097] <Actual sample spike experiment>

[0098] In order to explore the detection effect of UIO-66-NH2@Rh6G@SMIPs on rhodamine 6G in actual samples, this experiment tested the actual samples of lake water and dried chili peppers at 3, 5, and 7 μmol·L -1 Spiked recovery experiments of three concentrations of Rhodamine 6G.

[0099] Water from Lianhu Lake of Henan University of Technology was taken and filtered through a 0.22 μm filter membrane to collect the filtrate. Dried chili peppers were purchased from a local supermarket, 5 g of ground dried chili peppers were placed in a beaker, PBS buffer was added for ultrasonication for 10 min, and then filtered three times with a 0.22 μm filter membrane to collect the filtrate. The treated samples were prepared with rhodamine 6G spike concentrations of 3, 5, and 7 μmol·L -1 The solution was mixed with 30 mg UIO-66-NH2@Rh6G@SMIPs, oscillated on an oscillator for 30 min, filtered, washed with distilled water, and the filter cake was collected and dried naturally to measure its fluorescence spectrum. Under the same conditions, the above experiments were carried out in parallel for 3 groups.

[0100] The results are shown in Table 1. The recoveries of rhodamine 6G in lake water samples were 103.40%-104.19%, and the relative standard deviation (RSD) was 1.76%-3.05%. The recoveries of rhodamine 6G in dried chili samples were 103.66%-108.60%, and the RSD was 1.96%-3.70%. The results show that UIO-66-NH2@Rh6G@SMIPs can be applied to the detection of rhodamine 6G in actual samples.

[0101] Table 1

[0102] The present invention combines surface molecular imprinting technology with fluorescence sensing technology, and uses precipitation polymerization to polymerize the luminescent metal organic framework UIO-66-NH2 into the molecular imprinting polymer. By utilizing the dual characteristics of the luminescent metal organic framework as both a carrier and a fluorescence response signal, a surface molecular imprinting fluorescence sensor UIO-66-NH2@Rh6G@SMIPs that can specifically recognize rhodamine 6G is prepared.

[0103] The present invention characterizes the sensor by using a variety of methods, including infrared spectroscopy, X-ray diffraction, etc., to confirm that the UIO-66-NH2 and rhodamine 6G imprinting recognition sites have been successfully synthesized in the sensor; by analyzing the static adsorption curve, it is found that with the increase of the concentration of rhodamine 6G, the fluorescence peak of the sensor at 440nm gradually decreases, while the fluorescence peak at 560nm gradually increases, showing a ratio-type change; the dynamic adsorption curve is analyzed, and the results show that UIO-66-NH2@Rh6G@SMIPs can quickly and efficiently detect rhodamine 6G; using U IO-66-NH2@Rh6G@SMIPs was used to adsorb different interfering pigments and interfering ions. The results showed that UIO-66-NH2@Rh6G@SMIPs had excellent specific adsorption capacity and good anti-interference ability for rhodamine 6G. The fluorescence detection of UIO-66-NH2@Rh6G@SMIPs with and without rhodamine 6G for 14 days showed that it had good stability. In the application of actual samples, UIO-66-NH2@Rh6G@SMIPs had good adsorption capacity at the concentration of rhodamine 6G of 0-10μmol·L -1 The minimum detection limit was 12.77 nmol·L -1 ; When testing real samples of lake water and dried chili peppers, the sensor has good recovery rate and small relative standard deviation for rhodamine 6G.

[0104] In summary, the present invention successfully uses the luminescent metal organic framework as both a carrier and a fluorescent response group, and combines it with molecular imprinting technology to prepare a surface molecular imprinting fluorescent sensor UIO-66-NH2@Rh6G@SMIPs. The sensor has the advantages of good optical stability, high sensitivity, strong specific adsorption ability and good anti-interference, which meets the needs of accurately detecting rhodamine 6G in complex actual samples.

[0105] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a surface molecular imprinted fluorescence sensor based on UIO-66-NH2, characterized in that: The following steps are involved: S1: Dissolve UIO-66-NH2 in acetonitrile and perform ultrasonic treatment, then add warfarin and acrylic acid and perform ultrasonic treatment again, finally add ethylene glycol dimethacrylate and azobisisobutyronitrile, heat to 70-90° C. under an inert atmosphere, reflux for 7-9 hours, filter, and dry to obtain an intermediate; S2: using an eluent to elute the warfarin in the intermediate, and drying the eluted intermediate to obtain the surface molecular imprinting fluorescence sensor.

2. The method for preparing a surface molecular imprinted fluorescence sensor based on UIO-66-NH2 according to claim 1, characterized in that: The preparation method of UIO-66-NH2 is as follows: zirconium chloride and 2-aminoterephthalic acid are dissolved in an N,N-dimethylformamide aqueous solution, reacted at 110-130° C. for 22-26 hours, centrifuged, washed, and dried to obtain UIO-66-NH2.

3. The method for preparing a surface molecular imprinted fluorescence sensor based on UIO-66-NH2 according to claim 1, characterized in that: In step S1, the mass ratio of UIO-66-NH2 to warfarin is 2:1.4-1.

6.

4. The method for preparing a surface molecular imprinted fluorescence sensor based on UIO-66-NH2 according to claim 1, characterized in that: In step S2, the eluent is a mixture of methanol and acetic acid in a volume ratio of 4:

1.

5. The method for preparing a surface molecular imprinted fluorescence sensor based on UIO-66-NH2 according to claim 1, characterized in that: In step S2, the intermediate is placed in a Soxhlet extractor for elution at a temperature of 80-100°C.

6. The method for preparing a surface molecular imprinted fluorescence sensor based on UIO-66-NH2 according to claim 1, characterized in that: Step S2 specifically comprises: eluting the warfarin in the intermediate with an eluent until no warfarin is detected in the supernatant, eluting with pure methanol for 10-12 hours, and finally drying the eluted intermediate to obtain the surface molecular imprinting fluorescence sensor.

7. The method for preparing a surface molecular imprinted fluorescence sensor based on UIO-66-NH2 according to claim 1, characterized in that: The drying temperature in step S2 is 55-65°C.

8. A surface molecular imprinting fluorescence sensor based on UIO-66-NH2, characterized in that: The surface molecular imprinting fluorescence sensor is prepared by the method described in any one of claims 1 to 7, and is UIO-66-NH2@Rh6G@SMIPs.

9. Use of the surface molecular imprinting fluorescence sensor based on UIO-66-NH2 as claimed in claim 8 in detecting rhodamine 6G.

10. The use of the surface molecular imprinting fluorescence sensor based on UIO-66-NH2 in detecting rhodamine 6G according to claim 9, characterized in that: The detection environment was pH=7.0.

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