Sensing platform based on Eu-MOF metal organic framework and application of sensing platform in visual detection of cortisol

Abstract

The invention discloses a sensing platform based on an Eu-MOF metal organic framework and application of the sensing platform in visual detection of cortisol, the sensing platform contains a multi-emission fluorescent probe based on the Eu-MOF metal organic framework, and the fluorescent probe is obtained by coordination polymerization of 1, 3, 5-tri (4-carboxyphenyl) benzene and EuCl3. 6H2O; the red fluorescent material has the characteristic of generating dual emission at 454 nm and 615 nm under single-wavelength excitation (338 nm) so as to display red fluorescence. When cortisol is added into a sensing platform, the cortisol and the Eu-MOF metal organic framework form a compound, so that red fluorescence at 615 nm is reduced, blue fluorescence at 454 nm is gradually increased, a clear color change from red to blue is presented, corresponding color information can be identified through intelligent equipment, and then visual detection of the cortisol is realized. A novel sensing platform is provided for non-invasive measurement of the cortisol marker in the body fluid.

Description

Technical Field

[0001] This application belongs to the field of analytical detection technology, specifically relating to a sensing platform based on Eu-MOF metal-organic frameworks and its application in the visual detection of cortisol. Background Technology

[0002] Cortisol (CORT) is an important glucocorticoid secreted by the adrenal cortex. Studies have shown that cortisol participates in physiological processes such as anti-inflammation, immune regulation, and metabolic homeostasis. Its levels are closely related to stress, neuroendocrine-immune disorders, and various diseases, making it a key clinical biomarker. Therefore, point-of-care testing (POCT) of cortisol is of great significance for early disease warning, timely diagnosis and treatment, and personalized health management.

[0003] Portable fluorescence sensing technology has become an ideal choice for point-of-care testing (POCT) due to its high sensitivity, ease of operation, and low cost. Among them, lanthanide metal-organic framework (Eu-MOF) fluorescent probes have been widely used for biomarker detection due to their strong luminescence, high selectivity, and good photostability. However, existing Eu-MOF probes mostly rely on multi-wavelength excitation or multi-channel signal readout, which leads to problems such as strong instrument dependence, large signal interference, and inaccurate quantification. In addition, most probes have drawbacks such as single fluorescence signal, weak anti-interference ability, and difficulty in achieving internal control calibration, making it difficult to achieve accurate detection in complex samples (such as human body fluids such as serum and urine). Summary of the Invention

[0004] In view of this, the primary objective of this application is to provide a sensing platform based on Eu-MOF metal-organic frameworks, which constructs multi-emission fluorescent probes with single-wavelength excitation and multiple emission outputs based on Eu-MOF metal-organic frameworks, thereby overcoming the problems of signal instability and the need for multi-wavelength excitation of current Eu-MOF probes, and realizing accurate and reliable visual detection of cortisol, especially suitable for POCT application scenarios under portable fluorescence sensing platforms.

[0005] To achieve the above objectives, this application adopts the following technical solution: One aspect of this application discloses a sensing platform based on a Eu-MOF metal-organic framework, comprising a multi-emission fluorescent probe based on the Eu-MOF metal-organic framework. The multi-emission fluorescent probe is obtained by coordination polymerization of 1,3,5-tris(4-carboxyphenyl)benzene and EuCl3·6H2O. The multi-emission fluorescent probe has the characteristic of multi-emission under single-wavelength excitation, and under ultraviolet excitation at 338 nm, it generates dual emission at 454 nm and 615 nm, showing red fluorescence.

[0006] This application also discloses the application of the sensing platform described herein in the visual detection of cortisol.

[0007] Another aspect of this application discloses a method for detecting cortisol based on the sensing platform described in this application, comprising the following steps: After thoroughly mixing the Eu-MOF metal-organic framework-based multi-emission fluorescent probe with the sample to be tested and incubating it, the sample was irradiated with 338nm ultraviolet light, and the RGB values ​​were obtained by color analysis software. The quantitative detection of cortisol was achieved by analyzing the RGB values.

[0008] The beneficial effects of this application are: The fluorescent probe based on the Eu-MOF metal-organic framework constructed in this application has the characteristics of single-wavelength multi-emission. Under ultraviolet light excitation at 338 nm, it can emit red fluorescence at 454 nm and 615 nm. When cortisol (CORT) is added, it will combine with Eu-MOF to form Eu-MOF-CORT complex, which causes the red emission of Eu-MOF at 615 nm to gradually decrease, while the blue emission at 454 nm gradually increases. This results in a significant fluorescence color change from red to blue under ultraviolet light. By collecting the color signal change generated by the probe sensing area through a smart device, rapid and accurate detection of cortisol can be achieved.

[0009] The sensing platform of this application has great potential and practical value in realizing non-invasive detection of cortisol biomarkers in human body fluids (such as serum, urine, etc.), and is of great significance for promoting the widespread application of functionalized metal-organic framework fluorescent sensors in the fields of personal health monitoring, healthcare, disease early warning and diagnosis. Attached Figure Description

[0010] Figure 1 This application demonstrates the design of a fluorescent probe and detection platform based on an Eu-MOF metal-organic framework for monitoring cortisol in human body fluids; wherein, Figure 1 Figure A illustrates the hypothalamus-pituitary-adrenal (HPA) axis in the human body, which secretes and controls cortisol levels to cope with circadian rhythms and stress. ACTH: adrenocorticotropic hormone; CRH: corticotropin-releasing hormone. Cortisol in the hypertension, hyperlipidemia, and hypercholesterolemia axis can be excreted through salivary glands, urine, and sweat glands. Figure 1 Figure B demonstrates that, compared to saliva cortisol levels, serum cortisol monitoring can more accurately reflect the levels of cortisol metabolites in human body fluids. Figure 1 The C-C section showcases an Eu-MOF fluorescent probe for cortisol monitoring, which can rapidly detect human body fluids (subcutaneous serum and urine) and selectively and accurately identify cortisol. The strong interaction between cortisol and the probe triggers Eu-MOF fluorescence quenching, enabling efficient quantitative analysis.

[0011] Figure 2 The synthesis and potential bonding mechanism of the Eu-MOF metal-organic framework compounds in this application are demonstrated.

[0012] Figure 3 The characterization results of the Eu-MOF probes for monitoring cortisol in this application are presented; among them, Figure 3 In the image, A represents the infrared spectra of Eu-MOF and Eu-MOF-CORT with H3BTB as ligands. Figure 3 B is the Eu-MOF wide-scan XPS spectrum with ligand H3BTB; Figure 3 In the middle, C represents the XRD pattern of the Eu-MOF and Eu-MOF-CORT complex; Figure 3 Figure D is a schematic diagram of the absorption, migration and emission of Eu-MOF with antenna effect, where A represents absorption at 338 nm, F represents fluorescence, P represents phosphorescence (ISC: intersystem transition; ET: energy transfer; S: singlet state; T: triplet state).

[0013] Figure 4 The fluorescence response of the Eu-MOF probe in this application is shown in the presence and absence of CORT; among which, Figure 4 In Figure A, the fluorescence spectrum of the Eu-MOF probe containing 0-2 μM CORT is shown. Figure 4 Figure B shows the relationship between fluorescence intensity and CORT concentration at room temperature; Figure 4 In the figure, C represents the Zeta potential of the Eu-MOF and Eu-MOF-CORT complex; Figure 4 D is the histogram of selectivity and interference experiments (both cortisol and interferon concentrations are 5 μM).

[0014] Figure 5 The fluorescence response of the Eu-MOF probe to different temperatures in the presence or absence of CORT was demonstrated. Figure 5 In Figure A, the fluorescence spectrum of the Eu-MOF probe is shown in the absence of CORT at 15~40℃. Figure 5 B represents the fluorescence spectrum of the Eu-MOF probe in the presence of CORT at 15~40℃. Figure 5 C represents the fluorescence intensity ratio (I0.05). 615 / I 454 )0 / (I 615 / I 454 (I) Temperature variation curve, 615 / I 454 )0 represents the fluorescence intensity ratio without the addition of CORT, (I 615 / I 454 () represents the fluorescence intensity ratio after adding 2 μM CORT.

[0015] Figure 6The fluorescence response of the Eu-MOF probe to different pH values ​​in the presence or absence of CORT was demonstrated. Figure 6 In Figure A, the fluorescence spectrum of the Eu-MOF probe without CORT is shown in the pH range of 2 to 12 (the inset shows the fluorescence spectra of the Eu-MOF probe without CORT at pH 6.8, 7.4 and 8.5, respectively). Figure 6 In Figure B, the fluorescence spectra of Eu-MOF probes in the pH range of 2 to 12 under CORT conditions are shown (the insets show the fluorescence spectra of Eu-MOF probes containing CORT under pH conditions of 6.8, 7.4, and 8.5, respectively). Figure 6 C and D are (I 615 / I 454 )0 / (I 615 / I 454 The intensity ratio as a function of pH value is shown in the curve. 615 / I 454 )0 / (I 615 / I 454 (I) represents the fluorescence intensity ratio when 2 μM CORT is added at 20℃. 615 / I 454 () represents the fluorescence intensity ratio at 20℃ without the addition of CORT.

[0016] Figure 7 This study demonstrates the changing trends of RGB values ​​in different fluorescence images after reacting different concentrations of CORT in human body fluids with the sensing probe. According to the RGB value change curves, after reacting with 0-2 μM CORT, the R, G, and B values ​​in the fluorescence images gradually change, and the fluorescence color of the Eu-MOF sensing probe changes from red to blue under ultraviolet light. These results indicate that the designed probe can perform rapid, convenient, intuitive, and highly sensitive detection of CORT in real samples. Detailed Implementation

[0017] The embodiments of this application will be clearly and completely described below. The technical solutions in the embodiments described below are exemplary and only possible technical implementations of this application, not all possible implementations. Those skilled in the art can combine the embodiments of this application to obtain other embodiments without creative effort, and these embodiments are also within the protection scope of this application.

[0018] The first aspect of this application discloses a sensing platform based on a Eu-MOF metal-organic framework, containing a multi-emission fluorescent probe based on the Eu-MOF metal-organic framework. The multi-emission fluorescent probe is obtained by coordination polymerization of 1,3,5-tris(4-carboxyphenyl)benzene and EuCl3·6H2O. The multi-emission fluorescent probe has the characteristic of multi-emission under single-wavelength excitation. Under ultraviolet excitation at 338 nm, it generates dual emission at 454 nm and 615 nm, showing red fluorescence.

[0019] In this application, specific raw materials are selected for coordination polymerization to obtain multi-emission fluorescent probes based on Eu-MOF metal-organic frameworks. The different charges, radii, and interactions with metals carried by the anions of different metal salts, as well as the varying pH values ​​of the initial solutions, all influence the reaction process to some extent. This further alters the nucleation and growth rates of Eu-MOF, ultimately changing the self-assembly process of the Eu-MOF probes and resulting in probe compositions with different fluorescence properties. Figure 2 The multi-emission fluorescent probe based on the Eu-MOF metal-organic framework in this application has the characteristic of multi-emission under single-wavelength excitation. Under ultraviolet excitation of 338 nm, it generates dual emission at 454 nm and 615 nm, showing red fluorescence.

[0020] In this application, the Eu-MOF metal-organic framework is prepared by a solvothermal method, including the following steps: Provides a mixed solvent of H2O and DMAC; EuCl3·6H2O and 1,3,5-tris(4-carboxyphenyl)benzene were added to a mixed solvent and thoroughly mixed to obtain a pre-reaction solution. The pre-reaction solution was then subjected to a solvothermal reaction at 100-120℃ for 24-48 h to obtain the Eu-MOF metal-organic framework.

[0021] The proportions of the mixed solvent and raw materials can be determined or optimized experimentally without particular limitation. In some specific examples, the volume ratio of H2O to DMAC in the mixed solvent is 3:1, and the pH range of the mixed solvent is 6-9. In other specific examples, the molar concentration of EuCl3·6H2O in the pre-reaction solution is 0.1 mmol / L, and the molar ratio of EuCl3·6H2O to 1,3,5-tris(4-carboxyphenyl)benzene is 1:1.

[0022] In this application, the sensing platform includes a probe solution formed from the Eu-MOF metal-organic framework, which is formed by dispersing the Eu-MOF metal-organic framework in a buffer solution.

[0023] Suitable temperature and pH have a certain impact on the detection effect of the detection system, which can be determined experimentally by those skilled in the art. In this application, the detection temperature of the probe solution is 15-40℃, preferably 20℃, and the pH of the buffer solution is preferably 6-9. In some specific examples, the buffer solution is 2.5mM PBS buffer with a pH of 7.4.

[0024] It should be understood that the concentration of Eu-MOF metal-organic framework in the probe solution has a certain impact on the detection results. The specific concentration can be appropriately selected according to the experimental purpose or research needs. In the preferred example of this application, the concentration of Eu-MOF metal-organic framework in the probe solution is 10 mg / mL.

[0025] In some examples of this application, the sensing platform further includes: A stage configured to hold a probe solution; The ultraviolet lamp is configured to emit excitation light at 338 nm. And intelligent color acquisition devices, which are configured to acquire color signals from probe solutions and analyze them using color analysis software.

[0026] Among them, intelligent color acquisition devices can be devices with color acquisition functions such as cameras, mobile phones, and webcams. Preferably, intelligent color acquisition devices can also be equipped with color analysis software. However, it is easy to understand that color analysis software can also be performed by other devices, such as computers. There are no special limitations or requirements here.

[0027] The second aspect of this application discloses the application of the sensing platform described in the first aspect of this application in the visual detection of cortisol. It further discloses a method for detecting cortisol based on the sensing platform described in this application.

[0028] The multi-emission fluorescent probe based on the Eu-MOF metal-organic framework in this application has the advantage of single-wavelength excitation and multi-wavelength emission, exhibiting two emission centers at 454nm and 615nm under single excitation at 338nm. Upon addition of cortisol, a strong interfacial interaction occurs between cortisol CORT and Eu-MOF. With increasing CORT concentration, the red fluorescence of Eu-MOF at 615nm gradually decreases, while the blue fluorescence at 454nm gradually increases. Under UV illumination, the Eu-MOF probe displays a clear color change from red to blue, allowing for quantitative detection by identifying the corresponding color information using an intelligent color acquisition device. The potential bonding mechanism can be found in [reference needed]. Figure 2 .

[0029] The specific testing process includes the following steps: After thoroughly mixing the Eu-MOF metal-organic framework-based multi-emission fluorescent probe with the sample to be tested and incubating it, the sample was irradiated with 338nm ultraviolet light, and the RGB values ​​were obtained by color analysis software. The quantitative detection of cortisol was achieved by analyzing the RGB values.

[0030] In this application, the sample to be tested is human body fluid, and specific examples include, but are not limited to, urine and serum.

[0031] The present application will be further illustrated below with reference to specific embodiments. It should be noted that the specific embodiments below are for illustrative purposes only and do not limit the scope of the present application in any way.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0033] In addition, unless otherwise specified, methods without detailed conditions or steps are conventional methods, and the reagents and materials used are commercially available.

[0034] Example 1: Preparation of Eu-MOF metal-organic frameworks In this embodiment, Eu-MOF metal-organic frameworks were prepared by a solvothermal method, and the specific steps are as follows: EuCl3·6H2O (final concentration 0.1 mmol / L) and H3BTB (final concentration 0.1 mmol / L) were mixed in a H2O / N,N-dimethylacetamide-DMAC (volume ratio 3:1). The mixture was heated at 100 °C for 24 h in a polytetrafluoroethylene-lined reactor. After cooling to room temperature, the product was centrifuged and thoroughly washed three times with DMAC and deionized water. It was then dried in a vacuum oven at 50 °C to obtain a white powdery Eu-MOF metal-organic framework.

[0035] Example 2: Fluorescence detection of cortisol 2.1 Solution Preparation Probe solution: Disperse 5 mg of Eu-MOF metal-organic framework in 0.5 mL of 2.5 mM PBS buffer (pH 7.4) to form a probe solution.

[0036] CORT analysis solution: Weigh different masses of cortisol powder and dissolve them in PBS buffer solution to obtain 0.1-5 μM CORT analysis solution.

[0037] 2.2 Detection of Cortisol Detection was performed using fluorescence spectrophotometry, with the excitation wavelength set at 338 nm. The fluorescence spectral range was 300–800 nm, and the slit widths for both excitation and emission were set to 5–20 nm.

[0038] Mix the probe solution from section 2.1 with CORT analysis solution with a concentration of 0.1~5.0 μM, add PBS buffer solution, and then bring the volume to 3.0 mL with deionized water. Adjust the pH to 7.4. After incubating the suspension at 25 °C for 1 min, place it in a quartz cuvette for ultraviolet fluorescence detection.

[0039] Example 3 Characterization of Eu-MOF and its fluorescence system As is well known to those skilled in the art, the detection sensitivity of a fluorescent probe to an analyte is related to its own properties. In this application, FT-IR, UV-Vis, and fluorescence spectroscopy were used to study the Eu... 3+ The structural features and spectroscopic properties of the H3BTB ligand and Eu-MOF probe were determined. Furthermore, SEM and EDX were used to determine the morphology of the Eu-MOF and its Eu content. 3+ The distribution of them.

[0040] The results are as follows Figure 3 As shown, to further confirm the functional groups contained in Eu-MOF, Figure 3 Image A shows the FTIR spectra of H3BTB and the synthesized Eu-MOF. The 1582, 1522, and 1402 cm⁻¹ spectra are particularly prominent. -1 The wavenumbers are respectively attributed to -COO - Asymmetric and symmetric stretching vibrations, 476cm -1 Corresponding to Eu-O stretching vibration, confirming Eu 3+ It coordinates with the carboxyl group. Figure 3 The X-ray photoelectron spectroscopy (XPS) of the Eu-MOF shown in Figure B confirms the presence of europium. This is further confirmed by comparison with simulated spectra (…). Figure 3 The XRD data compared with those in C) prove that Eu-MOF was successfully synthesized. Figure 3 The D-test confirmed that the organic linker, after being excited to the S1 state, undergoes an intersystem transition to the T1 state. Subsequently, due to the efficient nonradiative energy transfer of the ligand triplet state (this process is the core mechanism of the antenna effect), Eu... 3+ The ions eventually emit light through radiative relaxation.

[0041] Example 4: Optimization of detection conditions and response to CORT in the Eu-MOF fluorescence system 4.1 Response of Eu-MOF fluorescence system to CORT Those skilled in the art know that the detection of an analyte by a fluorescent probe is related to its fluorescence intensity. An Eu-MOF fluorescent probe was prepared by using an appropriate formulation, which emits strong red fluorescence under ultraviolet light. Since the eye is very sensitive to red, upon addition of CORT and excitation at 338 nm, the fluorescent probe exhibits blue fluorescence under ultraviolet light, resulting in a noticeable visual color change. Therefore, the designed Eu-MOF fluorescent probe is feasible for the detection of CORT.

[0042] Cortisol at different concentrations was detected according to the method in Example 2. It can be seen that when CORT at a concentration of 0-2 μM reacts with the Eu-MOF probe, dual emission is generated at 454 nm and 615 nm. As the CORT concentration increases, the red fluorescence weakens and the blue fluorescence strengthens. Figure 4 (A) Fluorescence quenching is mainly caused by static quenching induced by the strong interaction between CORT and Eu-MOF. This mechanism has been used for the qualitative and quantitative analysis of CORT. Eu-MOF, after binding with cortisol... 3+ The red emission of the ligand decreases, while the blue emission of the ligand increases. The color of the Eu-MOF probe shows a continuous change from red to blue. The content of cortisol in the sample is detected by the degree of fluorescence change in the Eu-MOF fluorescence system.

[0043] Figure 4 Figure C illustrates the zeta potential of the Eu-MOF and Eu-MOF-CORT complex. The zeta potential of Eu-MOF is -8.99 mV. After adding a neutrally charged CORT molecule to the system, the zeta potential changes to 12.47 mV, verifying the interaction between Eu-MOF and CORT and confirming the strong interfacial interaction between CORT and Eu-MOF at the molecular scale. When dynamic equilibrium is reached, H2O enters the internal channels of Eu-MOFs, which can facilitate sampling and sensing and detection of target molecules.

[0044] 4.2 Effects of Temperature and pH on Fluorescent Probes As is well known to those skilled in the art, temperature and pH value have a certain influence on the fluorescence intensity of Eu-MOF probes. The probe solution was obtained according to the method in Example 2, and different temperatures and pH values ​​of the probe system were varied.

[0045] The results are as follows Figure 5 As shown, temperature changes have little effect on the fluorescence intensity of the detection fluorescent probe. After adding CORT, the fluorescence intensity of the Eu-MOF probe is similar at different temperatures ( Figure 5 Furthermore, it can be seen that at different temperatures (I) 615 / I 454 )0 and I 615 / I 454The similarity in the ratios indicates that temperature has little effect on CORT detection in this fluorescence system. As a preferred example, 20℃ is selected as the optimal temperature for detection by the Eu-MOF probe in this application.

[0046] Furthermore, Figure 6 The effect of pH on the fluorescent probe is shown. It can be seen that when the pH of the solution system is higher than 5.0, the initial fluorescence intensity of Eu-MOF at 615 nm decreases. Under conditions of pH 7.0 and without added CORT, Eu-MOF reaches its maximum fluorescence intensity at an excitation wavelength of 338 nm. When the pH is 7.4 and CORT is present in the system, the fluorescence intensity of the Eu-MOF probe at 615 nm decreases significantly. Since the Eu-MOF probe readily reacts with CORT under neutral conditions, pH 7.4 is also close to the optimal physiological pH tolerable by human body fluids. When the solution pH is higher than 7.0, Eu-MOF exhibits decreased fluorescence at 615 nm in the pH range of 7.0 to 12.0. Although the fluorescence intensity of the probe at 454 nm decreases slightly in the absence of cortisol, the decrease is not significant after adding cortisol to the system. Figure 6 The correlation curve shows that when the pH value is 7.4, (I 615 / I 454 )0 and I 615 / I 454 The fluorescence ratio tends to be relatively stable. As a preferred example, pH 7.4 is selected as the reaction condition for this fluorescence system.

[0047] 4.3 Detection of CORT using the Eu-MOF fluorescence system Prepare a 10 mg / mL probe solution and a 0-2 μM CORT standard solution according to the method in Example 2. Mix the probe solution with CORT analysis solutions of different concentrations at room temperature, add PBS buffer solution, and then make up to a volume of 3.0 mL with deionized water and adjust the pH to 7.4. After incubating the suspension at 25 °C for 1 min, use a fluorescence spectrometer to test the fluorescence intensity at 454 nm and 615 nm under 338 nm excitation.

[0048] With fluorescence intensity ratios of 454nm and 615nm, I 615 / I 454 A standard curve was plotted with CORT concentration on the x-axis and y-axis as the vertical axis. Figure 4 (B) exhibits good linearity in both the 0-1.0 μM and 1.0-2.0 μM ranges. Specifically, in the 0-1.0 μM range, the linear relationship is y1 = 4.591 - 1.453x1, R0 2The value is 0.979; in the range of 1.0–2.0 μM, the linear relationship is y² = 4.018–1.016x², R0 2 The value is 0.993. The calculated detection limit (LOD) of the probe is 0.0012 nM, and the linear range is 0-2.0 μM.

[0049] 4.4 Selectivity and anti-interference ability of Eu-MOF fluorescence system For an excellent fluorescence sensing system, it is crucial to possess good selectivity for CORT, maintaining a selective response to CORT even in the presence of interfering substances. Therefore, this application investigates the selectivity and anti-interference capability of the Eu-MOF sensing system in detecting CORT through a series of experiments.

[0050] Under the same conditions, choose Zn + Ca² + Mg² + K + Cl - The selectivity of the Eu-MOF fluorescence sensing system for CORT was evaluated using substances including glucose, urea, glutamic acid (Glu), histidine (His), phenylalanine (Phe), glycine (Gly), arginine (Arg), nicotinic acid, lactose, and albumin. The interfering components were prepared as follows: 0.0009 g of glucose powder was weighed and dissolved in 1 mL of PBS buffer solution. The solution was then diluted to 3.0 mL with deionized water, and the pH was adjusted to 7.4 to obtain a 5 μM glucose standard solution. Other interfering component standard solutions were prepared using the same method, differing only in the mass of the interfering substance added. In this experiment, the concentration of cortisol and the interfering substances was 5 μM.

[0051] The results are as follows Figure 4 As shown in Figure D, the fluorescence intensity ratio of the probe at 615 nm and 454 nm (I0) is significantly different. 615 / I 454 The change was not obvious, and the color change became fainter. However, after adding 5 μM cortisol, the probe's I... 615 / I 454 The fluorescence intensity decreased significantly. Similarly, the change in this ratio was not significant when a certain amount of other interfering molecules were added to the probe solution. After adding CORT, I 615 / I 454 The fluorescence intensity changed significantly. This indicates that the influence of other interfering components on CORT detection is almost negligible. Figure 4 The results from the study show that Eu-MOF has good selectivity and anti-interference ability in CORT detection.

[0052] Example 5: Detection of GA using a smartphone color recognizer Containing 0.5~1.0 mg·mL -1 The Eu-MOF suspension was sonicated for 1–3 min to achieve a homogeneous solution. The Eu-MOF suspension was then uniformly dropped into the grooves of a porous quartz plate, followed by the addition of 0.1–2.0 μM CORT standard solution. When the CORT concentration in the Eu-MOF-containing quartz plate reached a certain level, a significant fluorescence color change was observed under UV light. Different concentrations of CORT were added to the Eu-MOF fluorescence sensor, and a color-changing recording device for the sensing area was constructed for data acquisition and analysis. The experiment used a smartphone as a detector, a portable UV lamp as a light source, and a platform to hold the fluorescence sensor and the UV lamp.

[0053] The images of fluorescence color changes were taken with a camera in a dark environment. To ensure the reliability of the experimental results, each sample was measured at least three times, and the average value was taken before proceeding to the next step of the experiment.

[0054] The software acquires the color information corresponding to the red-green-blue (RGB) values ​​of the fluorescence photographs, plots a standard curve, and quantifies cortisol by analyzing the RGB values. To ensure data accuracy, the experiment was repeated five times to obtain the average R / B ratio, which represents the proportion of red and blue information.

[0055] In this test case, to achieve quantitative analysis, the same smartphone (iPhone 14 Pro, MQ1C3CH / A) was used to collect color signals from the fluorescence sensor applied to each eye, and the data was analyzed using color analysis software (ColorDesk APP) to achieve rapid and accurate detection of the target. When recording color changes in the sensing area, the Eu-MOF fluorescence sensor was placed on the stage, the ultraviolet lamp was turned on, and the smartphone recorded the color changes in the sensing area in real time. Using the phone's color recognition application, the color information corresponding to the red, green, and blue (RGB) values ​​of the photograph could be obtained. Therefore, cortisol was quantitatively detected by analyzing the RGB values. To ensure data accuracy, the experiment was repeated five times to obtain the average value of the red-blue information ratio (R / B).

[0056] Example 6: Analysis of GA in real samples using Eu-MOF To verify the ability of the Eu-MOF probe to detect cortisol in real samples, artificial urine and serum samples were first collected and diluted with PBS buffer. Samples were then prepared by adding 0.1–2.0 μM cortisol standard solution to the diluted urine and serum, resulting in a final cortisol concentration of 0.1–2.5 μM in the sample solutions. The samples were mixed with Eu-MOF at 20 °C for 1 min, and quantitative analysis was performed by monitoring the continuous emission intensity at a wavelength of 338 nm.

[0057] The results are as follows Figure 7 As shown, Figure 7 This study demonstrates the changing trends of RGB values ​​in different fluorescence images after reacting with a sensing probe at different concentrations of CORT in human body fluids. According to the RGB value change curves, after reacting with 0–2 μM CORT, the R, G, and B values ​​in the fluorescence images gradually change, and the fluorescence color of the Eu-MOF sensing probe changes from red to blue under ultraviolet light. These results indicate that the designed probe can perform rapid, convenient, intuitive, and highly sensitive detection of CORT in real samples.

[0058] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A sensing platform based on Eu-MOF metal-organic frameworks, characterized in that, The multi-emission fluorescent probe is based on the Eu-MOF metal-organic framework and is obtained by coordination polymerization of 1,3,5-tris(4-carboxyphenyl)benzene and EuCl3·6H2O. The multi-emission fluorescent probe has the characteristic of multi-emission under single-wavelength excitation. Under ultraviolet excitation of 338 nm, it produces dual emission at 454 nm and 615 nm and shows red fluorescence.

2. The sensing platform as described in claim 1, characterized in that, The Eu-MOF metal-organic framework was prepared by a solvothermal method, including the following steps: Provides a mixed solvent of H2O and DMAC; EuCl3·6H2O and 1,3,5-tris(4-carboxyphenyl)benzene were added to a mixed solvent and thoroughly mixed to obtain a pre-reaction solution. The pre-reaction solution was then subjected to a solvothermal reaction at 100-120℃ for 24-48 h to obtain the Eu-MOF metal-organic framework.

3. The sensing platform as described in claim 2, characterized in that, In the mixed solvent, the volume ratio of H2O to DMAC is 3:

1.

4. The sensing platform as described in claim 2, characterized in that, In the pre-reaction solution, the molar concentration of EuCl3·6H2O is 0.1 mmol / L, and the molar ratio of EuCl3·6H2O to 1,3,5-tris(4-carboxyphenyl)benzene is 1:

1.

5. The sensing platform as described in claim 2, characterized in that, The pH range of the mixed solvent is 6-9.

6. The sensing platform as described in claim 1, characterized in that, The sensing platform includes a probe solution formed by the Eu-MOF metal-organic framework, which is formed by dispersing the Eu-MOF metal-organic framework in a buffer solution. Preferably, the buffer solution is a 2.5 mM PBS buffer with a pH of 7.4; Preferably, the concentration of the Eu-MOF metal-organic framework in the probe solution is 10 mg / mL.

7. The sensing platform as described in claim 6, characterized in that, The sensing platform also includes: A stage configured to hold a probe solution; The ultraviolet lamp is configured to emit excitation light at 338 nm. And intelligent color acquisition devices, which are configured to acquire color signals from probe solutions and analyze them using color analysis software.

8. The application of the sensing platform as described in any one of claims 1-7 in the visual detection of cortisol.

9. A method for detecting cortisol based on the sensing platform according to any one of claims 1-7, characterized in that, Includes the following steps: After thoroughly mixing the Eu-MOF metal-organic framework-based multi-emission fluorescent probe with the sample to be tested and incubating it, the sample was irradiated with 338nm ultraviolet light, and the RGB values ​​were obtained by color analysis software. The quantitative detection of cortisol was achieved by analyzing the RGB values.

10. The method as described in claim 9, characterized in that, The sample to be tested is human bodily fluid.

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