Double-emission molecular imprinting fluorescence sensing detection method based on metal organic framework carrier

Abstract

According to the dual-emission molecularly imprinted fluorescence sensing detection method based on the metal organic framework carrier, the good carrier function of UiO-66, the excellent fluorescence performance of Mg / N-CDs and r-CdTe QDs and the specific recognition advantage of a molecularly imprinted layer are fused, in the presence of target molecules, fluorescence of Mg / N-CDs at 446 nm and fluorescence of r-CdTe QDs at 660 nm are quenched, and the fluorescence of Mg / N-CDs at 446 nm and fluorescence of r-CdTe QDs at 660 nm are quenched. Different fluorescence responses of the LHUatMIP can be used for detecting target molecules in a sample; when the fluorescent response signal is displayed, the color of the imprinted polymer changes along with different concentrations of the target molecules, so that the visual detection of the target molecules can be realized, and the specific sensitive detection of the target molecules in a complex sample is realized. The method has the advantages of being high in sensitivity, easy and convenient to operate, good in reproducibility, high in anti-interference performance and the like, rapid, specific and sensitive detection of explosives, synthetic precursors of the explosives and other imprinted molecules can be achieved by preparing imprinted polymers of different target molecules without fluorescence interference, and the method has wide application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of biochemical sensing detection and analysis, and specifically relates to a dual-emission molecular imprinting fluorescence sensing detection method including the preparation of a zirconium-based metal organic framework, magnesium nitrogen carbon dots and cadmium telluride quantum dots, the construction of a molecular imprinting fluorescence sensing polymer, ratio fluorescence sensitive detection and visual rapid detection. Background Art

[0002] Molecularly imprinted polymers (MIPs) mimic the high selectivity of antibodies and adsorb analytes by leaving a large number of imprinted cavities that match the template in structure, shape, and size. To date, MIPs have been applied in sensing, environmental science, food safety, biomedicine, and other fields due to their advantages such as high sensitivity, strong specificity, and simple synthesis. However, the synthesis of MIPs using bulk polymerization methods usually suffers from the problems of difficult elution and limited imprinting efficiency. In order to overcome these effects, it is very important to find a suitable carrier for molecular imprinting sensors.

[0003] Metal-organic frameworks (MOFs) are assembled by organic ligands and metal ions or metal clusters through coordination bonds. MOFs have extremely high specific surface area, uniform pore size, strong chemical customization ability and good thermal stability. Due to the elasticity of the composition, MOFs are often used in gas adsorption / storage, heterogeneous catalysis, luminescence and other fields. In addition, MOFs can also be used as nanomaterial scaffolds for loading organic probes for the design of optical and fluorescent chemical sensors. UiO-66 is a typical zirconium-based MOF that has been used as a support material for imprinted fluorescence sensing due to its porous structure, good thermal stability and ideal water stability. In addition, UiO-66, which has a high specific surface area and excellent signal transduction ability, provides more imprinting sites for imprinting preparation, thereby further improving the sensitivity of the sensor. However, the development of fluorescent sensors based on MOFs such as UiO-66 still has limitations such as low sensitivity, mainly due to the low fluorescence quantum yield (FLQY) of the luminescent quantum dots.

[0004] In summary, based on the demand for developing highly sensitive molecular imprinting sensing detection methods, it is extremely necessary to organically combine suitable metal organic framework carriers and luminescent materials with high fluorescence quantum yield to construct efficient molecular imprinting fluorescence sensors and establish a specific and sensitive new imprinting fluorescence sensing detection method. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] The present invention proposes a dual-emission molecular imprinting fluorescence sensing detection method based on a metal organic framework carrier. A typical zirconium-based metal organic framework UiO-66 is used as a carrier, and magnesium nitrogen carbon dots (Mg / N-CDs) and cadmium telluride quantum dots (r-CdTe QDs) with high fluorescence quantum yield are loaded and encapsulated to construct a novel dual-emission fluorescence imprinting sensor, so as to solve the technical problem of how to effectively realize specific and sensitive detection of detection samples and establish a molecular imprinting fluorescence sensing detection method with high sensitivity, strong selectivity and simple operation.

[0007] (II) Technical solution

[0008] In order to solve the above technical problems, the present invention proposes a dual-emission molecular imprinting fluorescence sensing detection method based on a metal organic framework carrier. The dual-emission molecular imprinting fluorescence sensing detection method comprises the following steps: preparing magnesium nitrogen carbon dots Mg / N-CDs with blue fluorescence, cadmium telluride quantum dots r-CdTe QDs with red fluorescence and UiO-66 carrier; using a target molecule as a template, 3-aminopropyltriethoxysilane APTES as a functional monomer, tetraethyl orthosilicate TEOS as a crosslinking agent, Mg / N-CDs and r-CdTe QDs as fluorophores, and UiO-66 as a carrier to prepare a molecular imprinting fluorescent polymer Mg / N-CDs / r-CdTe@UiO-66@MIP, and eluting the target molecule template; after combining the target molecule to be detected with the molecular imprinting polymer, the blue fluorescence of Mg / N-CDs at a wavelength of 446nm and the red fluorescence of r-CdTe The red fluorescence of QDs at a wavelength of 660 nm is quenched, showing a dual fluorescence response signal. At the same time, the color of the imprinted polymer changes with the concentration of the target molecule, realizing the visual detection of the target molecule.

[0009] Furthermore, the preparation of magnesium nitrogen carbon dots Mg / N-CDs includes the following steps: dispersing citric acid in ultrapure water, mixing with Mg(OH) 2 The mixture was fully mixed with ethylenediamine, added into a stainless steel autoclave lined with polytetrafluoroethylene, heated, cooled to room temperature after the reaction was completed, further purified by dialysis to obtain a light yellow solution, and freeze-dried to obtain Mg / N-CDs powder, which was stored at 4°C for future use.

[0010] Furthermore, the preparation of magnesium nitrogen carbon dots Mg / N-CDs includes the following steps: 10 g of citric acid is dispersed in 40 mL of ultrapure water, and 4.2 g of Mg(OH) 2 It was fully mixed with 5 mL of ethylenediamine, added into a 100 mL polytetrafluoroethylene-lined stainless steel autoclave, heated to 200 °C for 3 h, cooled to room temperature after the reaction was completed, and further purified by dialysis to obtain a light yellow solution. After freeze-drying, Mg / N-CDs powder was obtained and stored at 4 °C for later use.

[0011] Further, the preparation of cadmium telluride quantum dots r-CdTe QDs includes the following steps: tellurium powder and NaBH 4 dissolved in deionized water, and the mixture was stirred to obtain a NaHTe solution; at the same time, CdCl 2 2.5H 2 O and 3-mercaptopropionic acid are dissolved in deionized water, the pH value of the solution is adjusted with 1 mol / L NaOH, and the solution is stirred under a nitrogen environment to obtain a precursor solution; the NaHTe solution and the precursor solution are refluxed to obtain r-CdTe QDs.

[0012] Further, the preparation of cadmium telluride quantum dots r-CdTe QDs specifically includes the following steps: 25.5 mg of tellurium powder and 100 mg of NaBH 4 Dissolve in 1.5 mL of deionized water and stir the mixture for 8 h to obtain NaHTe solution. At the same time, 228 mg of CdCl 2 2.5H 2 O and 132 μL 3-mercaptopropionic acid were dissolved in 100 mL deionized water, the pH value of the solution was adjusted to 11.0 with 1 mol / L NaOH, and stirred for 30 min under a nitrogen environment to obtain a precursor solution; 1 mL NaHTe solution and 100 mL precursor solution were refluxed for 3 h to obtain r-CdTe QDs.

[0013] Furthermore, the preparation of UiO-66 comprises the following steps: ZrCl 4 and terephthalic acid were dissolved in DMF, stirred for 10 min, added into a stainless steel autoclave lined with polytetrafluoroethylene, heated, and after the reaction was completed and cooled to ambient temperature, washed three times with DMF and methanol, and dried in an oven overnight to obtain UiO-66 white powder.

[0014] Furthermore, the preparation of UiO-66 includes the following steps: 0.24 g ZrCl 4 and 0.17 g terephthalic acid were dissolved in 50 mL DMF, stirred at 25 °C for 10 min, added into a 100 mL polytetrafluoroethylene-lined stainless steel autoclave, heated to 120 °C for 24 h, and after the reaction was completed and cooled to ambient temperature, washed three times with DMF and methanol, and dried in an oven at 60 °C overnight to obtain UiO-66 white powder.

[0015] Furthermore, the preparation of molecularly imprinted fluorescent polymer Mg / N-CDs / r-CdTe@UiO-66@MIP includes the following steps: dispersing the synthesized UiO-66, Mg / N-CDs and r-CdTe QDs in a phosphate buffer solution, and dissolving the target molecule in a phosphate buffer solution; mixing the above two solutions, adding APTES, stirring, and then adding TEOS and NH 3 ·H 2 O; after the reaction is completed, the crude product is centrifuged and washed several times with a mixture of ethanol and acetonitrile until the template is no longer detectable in the supernatant under ultraviolet visible light at a wavelength of 350 nm, and then freeze-dried to obtain the molecularly imprinted fluorescent polymer Mg / N-CDs / r-CdTe@UiO-66@MIP.

[0016] Furthermore, the preparation of molecularly imprinted fluorescent polymer Mg / N-CDs / r-CdTe@UiO-66@MIP includes the following steps: 20 mg of synthesized UiO-66, 10 mg of Mg / N-CDs and 800 μL of r-CdTe QDs are dispersed in 5 mL of phosphate buffer solution, and 5 mg of target molecules are dissolved in 1 mL of PBS; the two solutions are mixed, and 120 μL of APTES is added, and after stirring for 1 h, 160 μL of TEOS and 160 μL of NH 3 ·H 2 O; after the mixture was reacted at 25°C for 12 hours, the crude product was centrifuged and washed several times with a mixture of ethanol and acetonitrile until the template could not be detected in the supernatant under ultraviolet visible light at a wavelength of 350 nm, and then freeze-dried to obtain the molecularly imprinted fluorescent polymer Mg / N-CDs / r-CdTe@UiO-66@MIP.

[0017] (III) Beneficial effects

[0018] The present invention proposes a dual-emission molecular imprinting fluorescence sensing detection method based on a metal organic framework carrier, which integrates the good carrier function of UiO-66, the excellent fluorescence performance of Mg / N-CDs and r-CdTe QDs, and the specific recognition advantage of the molecular imprinting layer. In the presence of target molecules, the fluorescence of Mg / N-CDs at 446nm and r-CdTe QDs at 660nm is quenched, and the different fluorescence responses of LHU@MIP can be used to detect target molecules in samples; while displaying the fluorescence response signal, the color of the imprinted polymer also changes with the concentration of the target molecule, so that the visual detection of the target molecule can also be realized, thereby realizing the specific and sensitive detection of the target molecule in the complex sample. This method has the advantages of high sensitivity, simple operation, good reproducibility, strong anti-interference, etc., and can also realize the rapid, specific and sensitive detection of explosives and their synthetic precursors and other imprintable molecules by preparing imprinted polymers of different target molecules without fluorescence interference, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 TEM photos of the products obtained in the examples of the present invention;

[0020] In the figure: A is Mg / N-CDs; B is r-CdTe QDs; C is UiO-66; D is LHU@MIP; E is LHU@NIP;

[0021] Figure 2 Element mapping diagram of the product LHU@MIP obtained in the embodiment of the present invention;

[0022] Figure 3 The XRD spectrum of the product obtained in the embodiment of the present invention;

[0023] In the figure: a is UiO-66; b is LHU@MIP; c is LHU@NIP;

[0024] Figure 4 FT-IR spectrum of the product obtained in the embodiment of the present invention;

[0025] Figure 5 The XPS spectrum of the product Mg / N-CDs obtained in the embodiment of the present invention;

[0026] In the figure: A is the full XPS spectrum of Mg / N-CDs; B is the high-resolution spectrum of C1s; C is the high-resolution spectrum of N1s; D is the high-resolution spectrum of O1s; E is the high-resolution spectrum of Mg1s;

[0027] Figure 6 Schematic diagram of the principle of dual-emission molecular imprinting fluorescence sensing for detecting TNP based on metal organic framework carrier;

[0028] Figure 7 The fluorescence spectra and Stern-Volmer plots of LHU@MIP and LHU@NIP at different 2,4,6-trinitrophenol (TNP) concentrations in the embodiments of the present invention;

[0029] In the figure: A is the fluorescence spectrum of LHU@MIP under different TNP concentrations (1, 2, 5, 10, 20, 30, 40, 50, 60, 70, 80, 100 μM); B is the fluorescence spectrum of LHU@NIP under different TNP concentrations (1, 2, 5, 10, 20, 30, 40, 50, 60, 70, 80, 100 μM); C is the Stern-Volmer plot of LHU@MIP; D is the Stern-Volmer plot of LHU@NIP;

[0030] Figure 8 is the fluorescence response of LHU@MIP and LHU@NIP to TNP and its analogs (concentration of 100 μM);

[0031] Fig. 9 The fluorescence responses of LHU@MIP and LHU@NIP to TNP and other interfering ions at a concentration of 100 μM;

[0032] Fig.10 The fluorescence responses of LHU@MIP and LHU@NIP to TNP and other interfering ions at a concentration of 4 mM;

[0033] Fig.11 is the stability of LHU@MIP;

[0034] Fig.12 is the reproducibility of LHU@MIP after adding 20 μM TNP;

[0035] Fig.13 The reusability of LHU@MIP in determining TNP;

[0036] Fig.14 Schematic diagram of TNP detection by smartphone and fluorescence images of LHU@MIP after adding different concentrations of TNP, as well as the corresponding linear relationship between R / B and TNP concentration (TNP concentration: 2, 5, 10, 20, 30, 40, 50, 60, 70, 80 μM);

[0037] Fig.15 The fluorescence color response of LHU@NIP to TNP and the corresponding linear relationship between R / B and TNP concentration (TNP concentration: 2, 5, 10, 20, 30, 40, 50, 60, 70, 80 μM). DETAILED DESCRIPTION

[0038] In order to make the purpose, content and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below in conjunction with the drawings and examples.

[0039] This embodiment proposes a dual-emission molecular imprinting fluorescence sensing detection method based on a metal organic framework carrier, and the dual-emission molecular imprinting fluorescence sensing detection method specifically includes the following steps:

[0040] 1. Preparation of Mg / N-CDs

[0041] Disperse 10 g of citric acid in 40 mL of ultrapure water and stir vigorously with 4.2 g of Mg(OH) 2 It was fully mixed with 5 mL of ethylenediamine, added into a 100 mL polytetrafluoroethylene-lined stainless steel autoclave, heated to 200 °C for 3 h, cooled to room temperature after the reaction was completed, and further purified by dialysis to obtain a light yellow solution. After freeze-drying, Mg / N-CDs powder was obtained and stored at 4 °C for later use.

[0042] 2. Preparation of r-CdTe QDs

[0043] 25.5 mg of tellurium powder and 100 mg of NaBH 4 Dissolve in 1.5 mL of deionized water and stir the mixture for 8 h to obtain NaHTe solution. At the same time, 228 mg of CdCl 2 2.5H 2 O and 132 μL 3-mercaptopropionic acid (MPA) were dissolved in 100 mL deionized water, the pH value of the solution was adjusted to 11.0 with 1 mol / L NaOH, and stirred for 30 min under a nitrogen environment to obtain a precursor solution; 1 mL NaHTe solution and 100 mL precursor solution were refluxed for 3 h to obtain r-CdTe QDs.

[0044] 3. Preparation of UiO-66

[0045] 0.24 g ZrCl 4 and 0.17 g terephthalic acid (H 2 BDC) was dissolved in 50 mL DMF, stirred at 25 °C for 10 min, added into a 100 mL polytetrafluoroethylene-lined stainless steel autoclave, heated to 120 °C for 24 h, and after the reaction was completed and cooled to ambient temperature, washed three times with DMF and methanol, and dried in an oven at 60 °C overnight to obtain UiO-66 white powder.

[0046] 4. Preparation of Molecularly Imprinted Fluorescent Polymer LHU@MIP

[0047] In this example, molecular imprinting polymers were prepared using 2,4,6-trinitrophenol (TNP), a precursor of explosives and drugs, as the detection target molecule. 20 mg of UiO-66, 10 mg of Mg / N-CDs, and 800 μL of r-CdTe QDs were dispersed in 5 mL of phosphate buffer solution (PBS, pH = 8, 10 mM), and 5 mg of TNP was dissolved in 1 mL of PBS. The two solutions were mixed, and 120 μL of APTES was added. After stirring for 1 h, 160 μL of TEOS and 160 μL of NH 3 ·H 2 O; after the mixture was reacted at 25°C for 12 hours, the crude product was centrifuged and washed several times with a mixture of ethanol and acetonitrile (v / v, 8:2) until the supernatant could not detect the template under ultraviolet visible light at a wavelength of 350nm, and the molecularly imprinted polymer Mg / N-CDs / r-CdTe@UiO-66@MIP (LHU@MIP) was obtained after freeze drying. In addition, as a comparison, the non-imprinted polymer LHU@NIP was prepared by the same procedure except that no template molecules were added.

[0048] 5. Characterization of Mg / N-CDs, r-CdTe QDs, UiO-66 and molecularly imprinted fluorescent polymers The products obtained in the above steps were characterized.

[0049] (1) TEM characterization

[0050] The morphology and structure of Mg / N-CDs, r-CDTe, UiO-66, LHU@MIP and LHU@NIP were characterized by TEM. Figure 1 As shown in Figure 1, Mg / N-CDs exhibit good dispersion and uniform size, with an average size of 2 nm. Figure 1 As shown in Figure B, the diameter of r-CdTe QDs is about 4 nm and the size is uniform. Figure 1 As shown in C, UiO-66 crystallites are typical rhombic octahedrons with an average size of 80 nm. Figure 1 The average size of LHU@MIP and LHU@NIP shown in Figures D and E is about 150 nm, which is larger than that of UiO-66, indicating that the materials were successfully prepared.

[0051] (2) Element mapping and element spectrum characterization

[0052] Elemental Spectrum ( Figure 2 ) showed that the imprinted polymer contained characteristic elements (Mg, N, Cd, Te, Zr, Si), proving that LHU@MIP was successfully prepared.

[0053] (3) XRD characterization

[0054] The crystal structures of UiO-66, LHU@MIP and LHU@NIP were characterized by XRD. Figure 3 As shown in Figure 2, the peaks at 2θ = 7.34°, 2θ = 8.48°, and 2θ = 25.7° confirm the successful synthesis of high-crystalline UiO-66. In addition, the diffraction peaks of LHU@MIP and LHU@NIP are different from those of UiO-66. The characteristic diffraction peaks of LHU@MIP and LHU@NIP (2θ = 23°) belong to amorphous SiO 2 The above results indicate that the imprinting layer was successfully prepared.

[0055] (4) FT-IR characterization

[0056] The surface functional groups of Mg / N-CDs, UiO-66, LHU@MIP and LHU@NIP were verified by FT-IR. Figure 4 As shown, Mg / N-CDs at 1577 cm -1 The peak at 1400 cm-1 belongs to the stretching vibration of -COO. -1 The peak at 1102cm belongs to the stretching vibration of C=O. -1 and 854cm -1 The peaks at 1584 cm-1 are related to the stretching vibration of CN and the bending vibration of NH. The results show that Mg / N-CDs were successfully prepared. -1 and 1397cm -1 The characteristic peak at 664 cm is attributed to the stretching mode of the carboxyl group, while the peak at 664 cm -1 and 747cm -1 The peak at 1644 cm is attributed to Zr-O. These results show that UiO-66 was successfully synthesized. -1 The peak at 1046cm is considered to be the stretching vibration of NH. -1 The peak at 766 cm belongs to the asymmetric Si-O-Si stretching. -1 and 450cm -1 The peaks at are related to Si-O vibration and Si-O-Si bending vibration, respectively. The results show that the imprinted silicon dioxide layer was successfully prepared. In summary, LHU@MIP was successfully prepared.

[0057] (5) XPS characterization

[0058] Figure 5 Shown are the XPS of Mg / N-CDs. Figure 5 Figure A shows the full XPS spectrum of Mg / N-CDs, including four elements: C, N, O, and Mg. Among them, the C1s XPS spectrum has peaks at 284.4eV, 286.0eV, and 288.1eV ( Figure 5B), attributed to CC / C=C, CO and C=O, respectively. The N1s XPS spectrum shows peaks at 399.5 eV, 400.7 eV and 401.5 eV, which belong to NC, NH and NO, respectively ( Figure 5 C in the middle). The O1s XPS spectrum shows the peaks of C=O (531.2 eV) and CO (533.2 eV) ( Figure 5 D). The Mg1s spectrum shows a peak at 1303.7 eV ( Figure 5 The above results indicate that magnesium and nitrogen elements were successfully doped to form Mg / N-CDs.

[0059] 6. Dual-emission molecular imprinting fluorescence sensing method based on metal organic framework support for detection of TNP

[0060] The principle of dual-emission molecular imprinting fluorescence sensing based on metal organic frameworks to detect TNP is as follows Figure 6 As shown. Based on the preparation of Mg / N-CDs, r-CdTe QDs and UiO-66, molecular imprinting polymers were synthesized by sol-gel method based on Mg / N-CDs and r-CdTe QDs (phosphors), UiO-66 (carrier), TNP (template), APTES (functional monomer) and TEOS (cross-linker). After removing TNP, LHU@MIP obtained a specific recognition cavity for TNP in size and shape. The use of UiO-66 provides a favorable carrier for the coating of Mg / N-CDs and r-CdTe QDs, and provides imprinting sites, which is beneficial to improve the imprinting efficiency. At an excitation wavelength of 350nm, the emission peaks of LHU@MIP at 446nm and 660nm are attributed to Mg / N-CDs and r-CdTe QDs, respectively. After adding TNP, the fluorescence at 446nm and 660nm can be effectively quenched. Therefore, the different fluorescence responses of LHU@MIP can be used to detect TNP in the sample. While displaying the fluorescent response signal, the color of the imprinted polymer also changes due to different concentrations of the target molecule, thereby enabling visual detection of the target molecule, thereby achieving specific and sensitive detection of the target molecule in complex samples.

[0061] Under the best optimized conditions, fluorescence measurements were performed using a fluorescence spectrometer after TNPs were combined with the imprinted polymer. Figure 7 As shown in Figures A and B, the fluorescence emission at 446 nm and 660 nm gradually weakened with the increase of TNP concentration. When the TNP concentration increased from 1 μM to 100 μM, the fluorescence intensity of LHU@MIP changed faster than that of LHU@NIP. Figure 7 As shown in C and D, the fluorescence response value (F 660 / F446 ) / (F 660 / F 446 ) 0 ) showed a good linear relationship with the concentration of TNP. The standard linear equations corresponding to LHU@MIP and LHU@NIP were y=0.0031x+0.9872 and y=0.0011x+0.9851, respectively. According to the 3σ / k standard, the limit of detection (LOD) of LHU@MIP was 0.56μM. Compared with LHU@NIP, LHU@MIP showed richer color changes to TNP (from blue to pink), indicating that LHU@MIP had higher selectivity for TNP due to its specific binding site. The imprinting factor (IF) was used to evaluate the imprinting effect of BR@MIP, and the calculated IF value was 2.82. The results showed that LHU@MIP had a stronger recognition ability for TNP.

[0062] 7. Selectivity and anti-interference performance of dual-emission molecular imprinting fluorescence sensing method based on metal organic framework support

[0063] The fluorescence responses of LHU@MIP and LHU@NIP to TNP and nine analogs (2-nitrophenol, 3-nitrophenol, 4-nitrophenol, catechol, resorcinol, hydroquinone, 2,4-dinitroaniline, phenol, and 24-dinitrophenol) were investigated to evaluate the selectivity of the imprinted fluorescence sensor. Figure 8 As shown, only TNP produced a more significant fluorescence response to LHU@MIP compared with other analogs, indicating that the TNP-imprinted cavity was specific.

[0064] In order to further verify the specificity of the prepared sensor in a complex environment, K + , Ca 2+ 、Na + 、Cl-、Cu 2+ 、SO 4 2- , Pb 2+ Mg 2+ 、Zn 2+ , Mn 2+ 、NO 3 - 、Ni + 、Co 2+ etc. have been studied as interfering substances. Fig. 9 and Fig.10 As shown in the figure, the concentrations of the above interfering ions are 100 μM and 4 mM, respectively. It can be seen that regardless of the concentration of the interfering substance, the fluorescence response of LHU@MIP to TNP is significantly higher than that of other interfering substances. The results show that these interfering substances will not affect the recognition of TNP by LHU@MIP.

[0065] 8. Stability, reproducibility and repeatability of sensor detection

[0066] The stability of LHU@MIP is investigated. The results are as follows Fig.11 As shown in Figure 2, within 20 days, the fluorescence response value (F 660 / F 446 ) / (F 660 / F 446 ) 0 ) did not change significantly, indicating that LHU@MIP has excellent fluorescence stability. To evaluate the reproducibility of the detection, 8 samples containing 20 μΜ TNP were tested and the fluorescence response of LHU@MIP was monitored. Fig.12 As shown in Figure 2, the fluorescence response value (F 660 / F 446 ) / (F 660 / F 446 ) 0 ) had no significant change. To evaluate the reusability of LHU@MIP, five removal-binding cycle experiments were performed. Fig.13 As shown, with the increase of the number of repetitions, ((F 660 / F 446 ) / (F 660 / F 446 ) 0 ) value decreased slightly and remained at 94.23% of the original value. This indicates that the imprinted sensing polymer has a relatively ideal reusability. The above results show that LHU@MIPs can be reused at least 5 times without obvious loss of detection ability.

[0067] 9. Simulation sample testing

[0068] In order to verify the feasibility of LHU@MIP in actual sample detection, river water, tap water and soil were selected as simulated samples for spike recovery experiments. The final concentrations of TNP in the spiked river water, tap water and soil were 5μM, 10μΜ and 20μM, respectively. The test results are shown in the table below. The recovery rates of TNP in river water, tap water and soil were 96.8%-100.2%, 96.9%-99.4% and 95.6%-99.15%, respectively, and the RSDs were all less than 3.1%. The results show that the constructed LHU@MIP sensor has good reliability and feasibility in detecting TNP in river water, tap water and soil.

[0069]

[0070] 10. Detection of TNP in samples using a smartphone-assisted fluorescence sensing platform

[0071] In order to achieve on-site detection of TNP and eliminate visual errors, a smartphone-based fluorescence sensing auxiliary platform was made to distinguish subtle color changes. Fluorescence color images were extracted using a smartphone and converted into RGB values ​​using professional software (ColorPicker). First, LHU@MIP containing different concentrations of TNP was incubated for 1 min. Then, under the same parameter conditions, a series of fluorescence images were obtained using a smartphone and further converted into RGB values ​​using Colorpicker. Fig.14 As shown in Figure 2, in the range of 2-80 μM, R / B and TNP concentration show a good linear relationship, that is, y = 0.0028x + 0.7512 (R 2 =0.986). At the same time, according to the 3σ / k standard, the LOD is 1.73μM. Compared with the LHU@NIP detection situation ( Fig.15 ), the color of LHU@MIP changed significantly from blue to green. The results showed that the combination of this detection method and the prepared smartphone-assisted fluorescence sensor platform can provide a reliable strategy for on-site analysis and detection of TNPs.

[0072] Similarly, river water, soil and tap water were used to investigate the practicality of the smartphone-based sensing platform. The results are shown in the table below. The recovery rate was 93.2%-99.1% and the RSD was <3.5%. The results show that the sensing platform achieved satisfactory results in detecting TNP, and this method has great potential in the on-site detection of TNP.

[0073]

[0074]

[0075] According to the above embodiments, the present invention uses zirconium-based metal organic framework UiO-66 as a functional carrier, and uses the blue fluorescence of Mg / N-CDs and the red fluorescence of r-CdTe QDs as response signals to establish a new dual-emission molecular imprinting fluorescence sensing detection method, which can effectively realize the rapid and sensitive detection of the target molecule TNP, with a detection limit of 0.56μM, and has the advantages of high sensitivity, simple operation, good reproducibility, and strong anti-interference. On this basis, a smartphone-assisted fluorescence sensing platform is constructed to realize portable on-site rapid detection of TNP in samples. This method can realize rapid and sensitive detection of explosives and their synthetic precursors and other imprintable molecules by preparing imprinted polymers of different target molecules without fluorescence interference, and has broad application prospects.

[0076] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A dual-emission molecular imprinting fluorescence sensing detection method based on a metal organic framework carrier, characterized in that: The dual-emission molecular imprinting fluorescence sensing detection method comprises the following steps: preparing magnesium nitrogen carbon dots Mg / N-CDs with blue fluorescence, cadmium telluride quantum dots r-CdTe QDs with red fluorescence and UiO-66 carrier; taking the target molecule as a template, 3-aminopropyltriethoxysilane APTES as a functional monomer, tetraethyl orthosilicate TEOS as a crosslinker, Mg / N-CDs and r-CdTe QDs as fluorophores, and UiO-66 as a carrier, preparing a molecular imprinting fluorescent polymer Mg / N-CDs / r-CdTe@UiO-66@MIP, and eluting the target molecule template; after the target molecule to be detected is combined with the molecular imprinting polymer, the blue fluorescence of Mg / N-CDs at a wavelength of 446nm and the red fluorescence of r-CdTeQDs at a wavelength of 660nm are quenched, showing a dual fluorescence response signal, and the color of the imprinting polymer changes with the concentration of the target molecule, thereby realizing the visual detection of the target molecule.

2. The dual-emission molecular imprinting fluorescence sensing detection method based on a metal organic framework carrier according to claim 1, characterized in that: The preparation of the magnesium nitrogen carbon dots Mg / N-CDs comprises the following steps: dispersing citric acid in ultrapure water, fully mixing with Mg(OH)2 and ethylenediamine under vigorous stirring, adding the mixture into a stainless steel autoclave lined with polytetrafluoroethylene, heating, cooling to room temperature after the reaction is completed, further purifying by dialysis to obtain a light yellow solution, freeze-drying to obtain Mg / N-CDs powder, and storing at 4°C for future use.

3. The dual-emission molecular imprinting fluorescence sensing detection method based on a metal organic framework carrier according to claim 2, characterized in that: The preparation of the magnesium nitrogen carbon dots Mg / N-CDs includes the following steps: dispersing 10g of citric acid in 40mL of ultrapure water, fully mixing with 4.2g of Mg(OH)2 and 5mL of ethylenediamine under vigorous stirring, adding into a 100mL polytetrafluoroethylene-lined stainless steel autoclave, heating to 200°C for 3h, cooling to room temperature after the reaction is completed, further purifying by dialysis to obtain a light yellow solution, and freeze-drying to obtain Mg / N-CDs powder, which is stored at 4°C for future use.

4. The dual-emission molecular imprinting fluorescence sensing detection method based on a metal organic framework carrier according to claim 1, characterized in that: The preparation of cadmium telluride quantum dots r-CdTe QDs comprises the following steps: dissolving tellurium powder and NaBH4 in deionized water, stirring the mixture to obtain a NaHTe solution; simultaneously, dissolving CdCl2·2.5H2O and 3-mercaptopropionic acid in deionized water, adjusting the pH value of the solution with 1 mol / L NaOH, stirring under a nitrogen environment to obtain a precursor solution; and refluxing the NaHTe solution and the precursor solution to obtain r-CdTe QDs.

5. The dual-emission molecular imprinting fluorescence sensing detection method based on a metal organic framework carrier according to claim 4, characterized in that: The preparation of the cadmium telluride quantum dots r-CdTe QDs specifically includes the following steps: dissolving 25.5 mg of tellurium powder and 100 mg of NaBH4 in 1.5 mL of deionized water, stirring the mixture for 8 hours to obtain a NaHTe solution; at the same time, dissolving 228 mg of CdCl2·2.5H2O and 132 μL of 3-mercaptopropionic acid in 100 mL of deionized water, adjusting the pH value of the solution to 11.0 with 1 mol / L NaOH, and stirring for 30 minutes in a nitrogen environment to obtain a precursor solution; reflux 1 mL of the NaHTe solution and 100 mL of the precursor solution for 3 hours to obtain r-CdTe QDs.

6. The dual-emission molecular imprinting fluorescence sensing detection method based on a metal organic framework carrier according to claim 1, characterized in that: The preparation of UiO-66 includes the following steps: dissolving ZrCl4 and terephthalic acid in DMF, stirring for 10 minutes, adding into a stainless steel autoclave lined with polytetrafluoroethylene, heating, and after the reaction is completed and cooled to ambient temperature, washing with DMF and methanol three times, and drying in an oven overnight to obtain UiO-66 white powder.

7. The dual-emission molecular imprinting fluorescence sensing detection method based on a metal organic framework carrier according to claim 6, characterized in that: The preparation of UiO-66 includes the following steps: dissolving 0.24 g ZrCl4 and 0.17 g terephthalic acid in 50 mL DMF, stirring at 25° C. for 10 min, adding into a 100 mL polytetrafluoroethylene-lined stainless steel autoclave, heating to 120° C. for 24 h, and after the reaction is completed and cooled to ambient temperature, washing with DMF and methanol three times, and drying in an oven at 60° C. overnight to obtain UiO-66 white powder.

8. The dual-emission molecular imprinting fluorescence sensing detection method based on a metal organic framework carrier according to claim 1, characterized in that: The preparation of the molecular imprinted fluorescent polymer Mg / N-CDs / r-CdTe@UiO-66@MIP comprises the following steps: dispersing the synthesized UiO-66, Mg / N-CDs and r-CdTe QDs in a phosphate buffer solution, and dissolving the target molecule in the phosphate buffer solution; mixing the two parts of the solution, adding APTES, stirring, and then sequentially adding TEOS and NH3·H2O; after the reaction is completed, centrifuging the crude product, and washing it with a mixed solution of ethanol and acetonitrile for multiple times until the template is not detected in the supernatant under ultraviolet visible light at a wavelength of 350nm, and freeze-drying to obtain the molecular imprinted fluorescent polymer Mg / N-CDs / r-CdTe@UiO-66@MIP.

9. The dual-emission molecular imprinting fluorescence sensing detection method based on a metal organic framework carrier according to claim 8, characterized in that: The preparation of the molecularly imprinted fluorescent polymer Mg / N-CDs / r-CdTe@UiO-66@MIP includes the following steps: 20 mg of synthesized UiO-66, 10 mg of Mg / N-CDs and 800 μL of r-CdTe QDs are dispersed in 5 mL of phosphate buffer solution, and 5 mg of the target molecule is dissolved in 1 mL of PBS; the two parts of the solution are mixed, 120 μL of APTES is added, and after stirring for 1 hour, 160 μL of TES and 160 μL of NH3·H2O are added in sequence; after the mixture is reacted at 25° C. for 12 hours, the crude product is centrifuged and washed with a mixed solution of ethanol and acetonitrile for multiple times until the template is not detected in the supernatant under ultraviolet visible light at a wavelength of 350 nm, and the molecularly imprinted fluorescent polymer Mg / N-CDs / r-CdTe@UiO-66@MIP is obtained after freeze drying.

Images