A carbon dot composite terbium metal organic framework material capable of identifying uric acid in urine

Abstract

The application relates to preparation and application of carbon dot composite terbium metal organic framework material which can be used for uric acid identification in urine. S1, raw materials are selected, including terbium nitrate, trimesic acid, ammonium bicarbonate and sodium citrate; S2, trimesic acid is dissolved and stirred; S3, terbium nitrate solution is added into the solution obtained in S2 and stirred; S4, standing, centrifugal drying and then white terbium metal organic framework material is obtained; S5, ammonium bicarbonate and sodium citrate are dissolved in deionized water, ultrasonic treatment is carried out, then the solution is transferred into a high-pressure reaction kettle and reacts; S6, the solution obtained in S5 is centrifuged, the supernatant is filtered by using a microporous filter membrane, nitrogen-doped carbon dots are obtained by dialysis; S7, different volumes of carbon dots are added into the terbium metal organic framework material and stirred; S8, carbon dot composite terbium metal organic framework material is obtained through centrifugal drying; and S9, the obtained carbon dot composite terbium metal organic framework material is used for uric acid detection.

Description

Technical Field

[0001] This invention relates to the field of preparation technology of carbon dot and lanthanide metal-organic framework composite materials, specifically to the preparation and application of a carbon dot composite terbium-based metal-organic framework material that can be used for the recognition of uric acid in urine. Background Technology

[0002] Uric acid (UA) is the end product of purine metabolism in the human body. Excessive uric acid leads to hyperuricemia, causing it to accumulate in the body and increasing the risk of kidney disease, cardiovascular disease, and metabolic syndrome. Therefore, exploring a sensitive method for effective and rapid urine detection is of great significance for clinical diagnosis. Reported methods for uric acid detection include electrochemical analysis, chromatography, spectrophotometry, Raman spectroscopy, enzyme catalysis, and fluorescence spectroscopy. Among these, fluorescence detection, with its advantages of ease of operation, short processing time, and high sensitivity, has shown significant application potential.

[0003] Lanthanide metal-organic frameworks (Ln-MOFs) provide a superior material basis for the construction of fluorescent probes due to their excellent optical properties, such as large Stokes shift, visual recognition, and long fluorescence lifetime. Traditional single-signal fluorescent probes are susceptible to interference from environmental and instrumental factors. Ratiometric fluorescent probes, however, possess self-calibration capabilities, enabling highly accurate and stable detection of target analytes. To further reduce testing errors and eliminate other interfering factors, guest molecules can be introduced. Carbon dots (CDs), as novel nanomaterials, possess advantages such as low toxicity and small size, making them ideal guest molecules. Therefore, developing a sensitive, rapid, and convenient fluorescent method for the detection of uric acid is of great significance. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a terbium-based metal-organic framework material that can be used for the preparation and application of a carbon dot composite material for the identification of uric acid in urine.

[0005] To achieve the above objectives, the present invention provides the following technical solution: Preparation and application of a terbium-based metal-organic framework material composed of carbon dots for the recognition of uric acid in urine, comprising the following steps:

[0006] S1, Select raw materials: terbium nitrate, pyromellitic acid, ammonium bicarbonate, and sodium citrate;

[0007] S2, Dissolve and stir the pyromellitic acid;

[0008] S3, add terbium nitrate solution to the solution obtained in S2 and stir;

[0009] S4, after standing, centrifugation and drying, yielded a white terbium-based metal-organic framework material;

[0010] S5, dissolve ammonium bicarbonate and sodium citrate in deionized water, sonicate, and then transfer the solution to a high-pressure reactor for reaction;

[0011] S6. The solution obtained in S5 is centrifuged, and then the supernatant is filtered using a microporous membrane. Nitrogen-doped carbon dots are then obtained by dialysis.

[0012] S7, Add carbon dots of different volumes to the terbium-based metal-organic framework material and stir;

[0013] S8, centrifugal drying yields terbium-based metal-organic framework materials with carbon dots;

[0014] S9, the obtained carbon dot composite terbium-based metal-organic framework material is used for the detection of uric acid.

[0015] Preferably, step S2 involves stirring at room temperature until completely dissolved, step S3 involves stirring at room temperature for 1 hour, step S7 involves stirring at room temperature for 24 hours, and step S5 involves sonication until fully dissolved.

[0016] Preferably, in step S4, the resting time is 12 hours, the drying temperature is 60 ℃, and the drying time is 24 hours.

[0017] Preferably, the reaction temperature in step S5 is 200 °C and the reaction time is 3 hours.

[0018] Preferably, in step S6, the size of the microporous filter membrane is 0.22 μm, the molecular weight cutoff of the dialysis membrane is 500 Da, and the dialysis time is 24 hours.

[0019] Preferably, in step S7, the volume of N-CDs is 5, 10, or 15 mL.

[0020] Preferably, the drying temperature in step S8 is 60 °C and the drying time is 24 hours.

[0021] Preferably, the detection in step S9 refers to the selectivity, anti-interference ability, and sensitivity of the material in recognizing uric acid in urine.

[0022] Compared with the prior art, the beneficial effects of the present invention are: the present invention uses rare earth terbium ions (Tb) 3+ A rare earth metal-organic framework is formed by combining pyromellitic acid (TMA) with free carboxyl groups, and then compounded with nitrogen-doped carbon dots (N-CDs) to obtain a ratiometric fluorescent probe, which can more sensitively and accurately identify and detect uric acid in urine. Attached Figure Description

[0023] Figure 1This is a schematic diagram illustrating the synthesis of the terbium-based metal-organic framework material with carbon dot composites that can be used for the recognition of uric acid in urine according to the present invention.

[0024] Figure 2 XRD patterns of N-CDs@Tb-MOFs composite material, Tb-MOFs and La(TMA)(H2O)6 single crystal simulated in this invention (a); FT-IR patterns of Tb-MOFs and N-CDs@Tb-MOFs composite material (b); Zeta potential diagrams of N-CDs, Tb-MOFs and N-CDs@Tb-MOFs materials (c); (d) Numerical histograms of Zeta potentials of N-CDs, Tb-MOFs and N-CDs@Tb-MOFs materials;

[0025] Figure 3 The excitation spectrum (a) and emission spectrum (b) of N-CDs in this invention are shown in the figure, and the inset is the CIE chromaticity diagram of N-CDs; the excitation spectrum (c) and emission spectrum (d) of Tb-MOFs are shown in the figure, and the inset is the chromaticity diagram of Tb-MOFs.

[0026] Figure 4 The excitation wavelengths of N-CDs and Tb-MOFs in this invention are shown in (a); the emission spectra of N-CDs@Tb-MOFs with different doping ratios at 316 nm are shown in (b).

[0027] Figure 5 The emission spectra of N-CDs@Tb-MOFs at excitation wavelengths of 316-336 nm (a) and N-CDs@Tb-MOFs at excitation wavelengths of 318-326 nm (b) are shown in this invention.

[0028] Figure 6 The inset shows the emission spectrum of N-CDs@Tb-MOFs at 322 nm in this invention, with the CIE plot of N-CDs@Tb-MOFs in the inset.

[0029] Figure 7 Waterfall plots of emission spectra of N-CDs@Tb-MOFs composite materials in different urine compositions in this invention (Inset: Comparison of N-CDs@Tb-MOFs composite materials before and after identifying uric acid under UV light) (a); Pie chart of fluorescence intensity ratios of N-CDs@Tb-MOFs composite materials in solutions with different urine compositions (I) 544 / I 433 (b); Quenching rate of N-CDs@Tb-MOFs in solutions containing different urine components (c); Response of N-CDs@Tb-MOFs composites to uric acid in the presence of other interfering components (d);

[0030] Figure 8The different UA concentrations and N-CDs@Tb-MOFs fluorescence intensity ratios in this invention (I 544 / I 433 A linear relationship between ( ). Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1:

[0033] See Figure 1 The preparation and application of a carbon dot composite terbium-based metal-organic framework material for recognizing uric acid in urine are described below:

[0034] S1, Select raw materials: terbium nitrate, pyromellitic acid, ammonium bicarbonate, and sodium citrate;

[0035] S2, Dissolve and stir the pyromellitic acid;

[0036] S3, add terbium nitrate solution to the solution obtained in S2 and stir;

[0037] S4, after standing, centrifugation and drying, yielded a white terbium-based metal-organic framework material;

[0038] S5, dissolve ammonium bicarbonate and sodium citrate in deionized water, sonicate, and then transfer the solution to a high-pressure reactor for reaction;

[0039] S6. The solution obtained in S5 is centrifuged, and then the supernatant is filtered using a microporous membrane. Nitrogen-doped carbon dots are then obtained by dialysis.

[0040] S7, Add carbon dots of different volumes to the terbium-based metal-organic framework material and stir;

[0041] S8, centrifugal drying yields terbium-based metal-organic framework materials with carbon dots;

[0042] S9, the obtained carbon dot composite terbium-based metal-organic framework material is used for the detection of uric acid.

[0043] Furthermore, in step S2, the mixture is stirred at room temperature until completely dissolved; in step S3, the mixture is stirred at room temperature for 1 hour; in step S7, the mixture is stirred at room temperature for 24 hours; and in step S5, the mixture is sonicated until fully dissolved.

[0044] Furthermore, in step S4, the standing time is 12 hours, the drying temperature is 60 ℃, and the drying time is 24 hours.

[0045] Furthermore, in step S5, the reaction temperature is 200 °C and the reaction time is 3 hours.

[0046] In step S6, the microporous filter membrane has a size of 0.22 μm, the dialysis membrane has a molecular weight cutoff of 500 Da, and the dialysis time is 24 hours.

[0047] Furthermore, in step S7, the volume of N-CDs is 5, 10, or 15 mL.

[0048] Furthermore, in step S8, the drying temperature is 60 ℃ and the time is 24 hours.

[0049] Furthermore, the detection in step S9 refers to the selectivity, anti-interference ability, and sensitivity of the material in recognizing uric acid in urine.

[0050] Among them, the prepared carbon dot composite terbium-based metal-organic framework material was used for selective testing of different urine components: at room temperature, 3 mg of N-CDs@Tb-MOFs sample was weighed and dispersed in 4 mL of water, and 1 mL of a 10% concentration was taken. -2 A mol / L solution of urine components (uric acid, glucose, urea, hippuric acid, creatinine, creatine, TDGA, NaCl, KCl, NH4Cl) was added to the N-CDs@Tb-MOFs dispersion. The mixture was then sonicated to form a homogeneous and stable solution containing urine components, and the prepared solution was subjected to fluorescence testing.

[0051] The prepared carbon dot composite terbium-based metal-organic framework (N-CDs@Tb-MOFs) was used to test its anti-interference ability in the detection of uric acid in the presence of different urine components: At room temperature, 3 mg of N-CDs@Tb-MOFs sample was weighed and dissolved in 3 mL of water, and 1 mL of 10% terbium hydroxide solution was added to each solution. -2 A urine component solution (uric acid, glucose, urea, hippuric acid, creatinine, creatine, TDGA, NaCl, KCl, NH4Cl) was prepared, and then a solution with a concentration of 10 mol / L was added. -2 A mol / L aqueous solution of uric acid was prepared. The mixture was then sonicated until a homogeneous and stable solution containing urinary components was formed. Finally, the prepared solution was subjected to a fluorescence test.

[0052] Sensitivity testing of the prepared carbon dot composite terbium-based metal-organic framework (N-CDs@Tb-MOFs) for uric acid detection: The sensitivity was calculated by measuring the fluorescence intensity of uric acid at different concentrations in aqueous solution. 3 mg of N-CDs@Tb-MOFs sample was dissolved in 4 mL of water, and 1 mL of uric acid at different concentrations (1×10⁻⁶) was added. -5 5×10 -4 1×10 -3 2×10 -3 2.5×10 -3 5×10 -3 The mixture was then placed in an aqueous solution (M) and sonicated until a homogeneous and stable solution containing urine components was formed. Finally, the prepared solution was subjected to a fluorescence test.

[0053] The structure of the sample was characterized. The sample is a terbium-based metal-organic framework material and a terbium-based metal-organic framework material composed of carbon dots.

[0054] XRD spectrum analysis: The samples were analyzed using an X-ray diffraction spectrometer from Beijing Puxi General Instrument Co., Ltd.

[0055] To investigate the structure of the obtained product, XRD was used to characterize it. Figure 2 (a) Shows the simulated XRD patterns of nitrogen-doped carbon dot composite terbium trimellitate (N-CDs@Tb-MOFs), terbium trimellitate (Tb-MOFs), and La(TMA)(H2O)6 single crystals, respectively. It can be clearly seen that the peak positions of the prepared N-CDs@Tb-MOFs and Tb-MOFs correspond to those of the theoretical crystal, indicating that the prepared composite materials Tb-MOFs and N-CDs@Tb-MOFs are pure phases and there are no other impurity peaks.

[0056] Infrared spectroscopy analysis: Infrared analysis (IR) was performed using a Thermo Fisher Scientific Nicoleti S200 Fourier transform infrared spectrometer to detect the functional groups and structures of Tb-MOFs and N-CDs@Tb-MOFs samples, with a wavenumber range of 4000-400 cm⁻¹. -1 ;

[0057] like Figure 2 As shown in (b), it should originally be at 1280 cm. -1 and 1690-1730 cm -1 The characteristic peak corresponding to free H3BTC disappeared. This verifies the interaction between MOF ligands and Tb. 3+ Successful coordination of ions and formation of Tb-MOF structures. 3412-3483 cm⁻¹ -1The broad peak observed at 1375 cm⁻¹ is attributed to the stretching vibration of the coordinated water molecule OH. -COOH at 1375 cm⁻¹ -1 -1437 cm -1 Symmetric stretching vibration at 1560 cm and at 1560 cm -1 -1614 cm -1 Asymmetric stretching vibration centered at 707 cm -1 and 762 cm -1 The peak at 531 cm⁻¹ belongs to the out-of-plane CH bending vibration mode of the aromatic ring of the organic linker. -1 The peak belongs to the stretching vibration of Tb-O. This is consistent with previous reports.

[0058] Zeta potential analysis: Figure 2 (c) and (d) show the Zeta potential values ​​of N-CDs, Tb-MOFs, and N-CDs@Tb-MOFs. The Zeta potential (ζ) is a key indicator representing the surface charge density of colloidal particles. A negative value indicates that the particle surface is negatively charged (this originates from the dissociation of acidic functional groups on the surface, such as -COOH and -OH); the larger the absolute value, the more negative charge on the surface, the stronger the electrostatic repulsion between colloidal particles, and the more stable the system; the smaller the absolute value, the lower the surface negative charge density (or that it is partially shielded). N-CDs exhibit a negative potential of approximately -9.58 mV, Tb-MOFs exhibit a negative potential of approximately -6.67 mV, while the Zeta potential of N-CDs@Tb-MOFs is approximately -6.37 mV, demonstrating a certain electrostatic interaction between the two. This proves the successful synthesis of N-CDs@Tb-MOFs.

[0059] Furthermore, the performance of the carbon dot composite terbium-based metal-organic framework material (N-CDs@Tb-MOFs) of this invention was characterized.

[0060] Excitation and emission spectra of N-CDs: Figure 3 (a) and (b) are the excitation and emission spectra of N-CDs, respectively. It can be seen that the excitation wavelength of N-CDs is 361 nm and its emission wavelength is 440 nm, which is a typical blue-emitting carbon dot. Figure 3 The illustration in (b) shows more intuitively that it is located at coordinates (0.150, 0.081) on the CIE chromaticity diagram, in the blue area, which further confirms that it is a blue carbon dot.

[0061] Excitation and emission spectra of Tb-MOFs: Figure 3 (c) is the excitation spectrum of Tb-MOFs, with the excitation peak located at 267 nm. Figure 3(d) is the emission spectrum of Tb-MOFs, with an emission peak at 544 nm, indicating a distinct green-emitting material. The emission spectrum of Tb-MOFs is at 488 nm ( 5 D4→ 7 F6), 544 nm 5 D4→ 7 F5), 582 nm 5 D4→ 7 F4) and 623 nm 5 D4→ 7 Tb is shown at F3) 3+ Characteristic ionic transitions. Figure 2 (d) can be clearly seen in the chromaticity diagram of the illustration to be in the green area, where the coordinates (0.257, 0.597) are in the green area.

[0062] Emission spectra of N-CDs@Tb-MOFs: In order to find a suitable excitation wavelength for the investigation of doping ratio, such as... Figure 4 As shown in (a), the excitation wavelengths of N-CDs and Tb-MOFs have a clear intersection at 316 nm. Therefore, 316 nm was chosen as the excitation wavelength to investigate subsequent doping ratios. To determine the optimal doping ratio for the ratiometric fluorescent probe, 5 mL, 10 mL, and 15 mL of N-CDs were added to 50 mg of Tb-MOFs sequentially, as follows: Figure 4 (b) Fluorescence tests were performed on the three composite materials. The results clearly showed that the carbon peaks in the composite material obtained from 5 mL N-CDs + 50 mg Tb-MOFs were not obvious; the carbon peaks in the composite material obtained from 15 mL N-CDs + 50 mg Tb-MOFs were too abrupt; only the intensity and morphology of the two fluorescence peaks in the 10 mL N-CDs + 50 mg Tb-MOFs mixture were more suitable for subsequent fluorescence testing. Therefore, the optimal doping ratio for the composite material was finally determined to be 10 mL N-CDs + 50 mg Tb-MOFs.

[0063] To determine the optimal excitation wavelength for the N-CDs@Tb-MOFs composite material in subsequent fluorescence testing, the fluorescence emission spectrum of the overlapping excitation wavelengths of N-CDs and Tb-MOFs was first measured. When the excitation wavelength was ≤316 nm, the fluorescence peak intensity at 544 nm was too high to be monitored. Therefore, the emission spectrum for excitation wavelengths between 316 nm and 336 nm is shown below. Figure 5 As shown in (a). Next, the detection range was further narrowed, selecting 318 nm–326 nm as the excitation wavelength monitoring range. The emission spectrum obtained with the excitation wavelength of 318 nm–326 nm is shown below. Figure 5 As shown in (b), finally, the peak value I is determined.433 / I 544 When the ratio is 1:2, that is, 322 nm is the excitation value for subsequent fluorescence measurements of N-CDs@Tb-MOFs.

[0064] When the excitation wavelength of the N-CDs@Tb-MOFs composite material is 322 nm, the emission spectrum is as follows: Figure 6 As shown, it exhibits two distinct emission peaks at 433 nm and 544 nm, corresponding to the emission peaks of N-CDs and Tb-MOFs, respectively. Therefore, the N-CDs@Tb-MOFs composite material is a blue-green dual-emission material. The CIE chromaticity diagram in the inset further confirms this, with the coordinates located at the (0.190, 0.260) boundary of the blue-green chromaticity diagram.

[0065] Example 2

[0066] The present invention utilizes a carbon dot composite terbium-based metal-organic framework material as a fluorescent probe for the detection of uric acid.

[0067] Selectivity: The obtained N-CDs@Tb-MOFs were respectively reacted with a concentration of 10 -2 The fluorescence spectra of 10 mol / L urine components were measured, as follows: Figure 7 As shown in (a) and (b), it is easy to see that the N-CDs@Tb-MOFs composite material has a significant response to UA. After the addition of UA, the fluorescence peak at 544 nm in the composite material is significantly quenched, but the fluorescence peak at 433 nm remains basically unchanged. This fluorescent probe is a typical "single-variable constant type". Figure 7 The inset in (a) is a color comparison of the N-CDs@Tb-MOFs composite material before and after the addition of UA under a UV dark chamber. After adding UA, the green color immediately becomes lighter. Figure 7 (c) The fluorescence intensity ratio I of the N-CDs@Tb-MOFs composite material is only increased when UA is added. 544 / I 433 There was a clear quenching phenomenon; no significant changes were observed when other urinary components were added, and the quenching rate was as high as 91.2%.

[0068] Interference resistance: Interference resistance is an important indicator of fluorescent probes; therefore, we conducted interference resistance experiments on N-CDs@Tb-MOFs materials. For example... Figure 7 As shown in (d), the addition of uric acid also leads to I in the presence of other urinary components (glucose, urea, hippuric acid, creatinine, creatine, TDGA, NaCl, KCl, NH4Cl). 544 / I 433The reduction in uric acid levels demonstrates that the composite material exhibits excellent anti-interference capabilities against uric acid (UA), and the fluorescent probe can still clearly identify uric acid even in the presence of other urine components. This material provides certain conditions for future applications as a fluorescent probe.

[0069] Sensitivity: Sensitivity is another important indicator of fluorescent probes, which determines the practical application value of the material. Figure 8 The linear relationship between N-CDs@Tb-MOFs composites and uric acid is shown. This is when the uric acid concentration is 0-5 × 10⁻⁵. -3 At time M, the N-CDs@Tb-MOFs composite material exhibits excellent linearity for uric acid, as shown in equation I. 544 / I 433 = 1.71252-151.4627 [C], R 2 =0.9999. This indicates that the material is an excellent fluorescent probe for detecting uric acid. The limit of detection (LOD) was calculated to be 0.15 μM using the formula 3σ / K. To highlight the advantages of ratiometric fluorescent probes, fluorescence tests were performed on Tb-MOFs with added uric acid.

[0070] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. The preparation and application of a carbon dot composite terbium-based metal-organic framework material for the recognition of uric acid in urine, characterized in that... The following are the operating steps: S1, Select raw materials: terbium nitrate, pyromellitic acid, ammonium bicarbonate, and sodium citrate; S2, Dissolve and stir the pyromellitic acid; S3, add terbium nitrate solution to the solution obtained in S2 and stir; S4, after standing, centrifugation and drying, yielded a white terbium-based metal-organic framework material; S5, dissolve ammonium bicarbonate and sodium citrate in deionized water, sonicate, and then transfer the solution to a high-pressure reactor for reaction; S6. The solution obtained in S5 is centrifuged, and then the supernatant is filtered using a microporous membrane. Nitrogen-doped carbon dots are then obtained by dialysis. S7, Add carbon dots of different volumes to the terbium-based metal-organic framework material and stir; S8, centrifugal drying yields terbium-based metal-organic framework materials with carbon dots; S9, the obtained carbon dot composite terbium-based metal-organic framework material is used for the detection of uric acid.

2. The terbium-based metal-organic framework material with carbon dot composites for the recognition of uric acid in urine according to claim 1, characterized in that: In step S2, the mixture is stirred at room temperature until completely dissolved; in step S3, the mixture is stirred at room temperature for 1 hour; in step S7, the mixture is stirred at room temperature for 24 hours; and in step S5, the mixture is sonicated until fully dissolved.

3. The terbium-based metal-organic framework material with carbon dots for recognizing uric acid in urine according to claim 1, characterized in that: In step S4, the settling time is 12 hours; in steps S4 and S8, the drying temperature is 60 ℃ and the time is 24 hours; in step S5, the reaction temperature is 200 ℃ and the time is 3 hours; in step S6, the size of the microporous filter membrane is 0.22 μm, the molecular weight cutoff of the dialysis membrane is 500 Da, and the dialysis time is 24 hours.

4. The terbium-based metal-organic framework material with carbon dot composites for recognizing uric acid in urine according to claim 1, characterized in that: In step S7, different volumes of N-CDs are added to the terbium-based metal-organic framework material and stirred (volumes of 5, 10, and 15 mL, respectively).

5. The terbium-based metal-organic framework material with carbon dot composites for the identification of uric acid in urine according to claim 1, characterized in that: The detection in step S9 refers to the selectivity, anti-interference ability, and sensitivity of the material in recognizing uric acid in urine.

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