A method for preparing carbon quantum dots, carbon quantum dots, applications, and a method for detecting rifampicin concentration.

Abstract

This invention provides a method for preparing carbon quantum dots, the carbon quantum dots themselves, their applications, and a method for detecting rifampicin concentration. The method includes: mixing 2-hydroxyaniline and ethylenediamine dihydrochloride in a solvent, then transferring the mixture to a reaction vessel and heating it to obtain the carbon quantum dots. Compared to other carbon quantum dots that can detect rifampicin concentration through bimodal ratios, the carbon quantum dots of this invention, after being mixed with rifampicin, exhibit [F...]. 381 The reduction amount and F 443 The reduction amounts are more significantly different, which makes the carbon quantum dots of the present invention have higher detection accuracy and lower detection limit for rifampicin.

Description

Technical Field

[0001] This invention relates to the field of rifampicin detection, and in particular to a method for preparing carbon quantum dots, carbon quantum dots, their applications, and a method for detecting rifampicin concentration. Background Technology

[0002] Rifampin (RIF) is a broad-spectrum antibiotic belonging to the rifamycin family, and it plays an important role in controlling bacterial diseases in fish, including saddleback disease caused by bacteria. As a lipophilic compound, RIF readily penetrates the cell barrier via passive transport, leading to its rapid distribution throughout the aquatic product and its accumulation within the product.

[0003] Long-term consumption of the aforementioned aquatic products can easily induce adverse reactions such as joint pain, allergic rashes, and neurological disorders. More seriously, it may induce severe reactions such as liver necrosis. Furthermore, reactive oxygen species (RIFs) enter the environment through animal metabolism and excretion, causing water pollution and posing a potential threat to aquatic ecosystems. Given their persistence in the environment and potential health risks, accurate and sensitive monitoring of RIFs is crucial for mitigating ecological pollution and ensuring food safety.

[0004] To date, various methods exist for detecting RIFs, such as high-performance liquid chromatography (HPLC), thin-layer chromatography (TLC), capillary electrophoresis (CE), real-time polymerase chain reaction (RT-PCR), and molecularly imprinted electrochemiluminescence (MIECL). However, these methods often suffer from drawbacks such as long detection times, complex procedures, and expensive equipment, limiting their applicability in rapid and on-site visual analysis.

[0005] In comparison, using carbon dots for RIF monitoring offers advantages such as low cost and ease of operation. However, it is worth noting that carbon dots often exhibit strong detection specificity when performing substance detection, resulting in a limited number of carbon dot types that can actually be used for RIF monitoring. Furthermore, these available carbon dots often suffer from lower detection accuracy and relatively higher detection limits during RIF detection. Summary of the Invention

[0006] Therefore, it is necessary to address the problem of insufficient accuracy in rifampicin concentration detection by providing a method for preparing carbon quantum dots, the application of carbon quantum dots, and a method for detecting rifampicin concentration.

[0007] The technical solution provided by this invention is as follows:

[0008] A method for preparing carbon quantum dots, comprising:

[0009] 2-hydroxyaniline and ethylenediamine dihydrochloride are mixed in a solvent and then transferred to a reaction vessel for heating to obtain the carbon quantum dots.

[0010] In some embodiments of this application, the mass ratio of 2-hydroxyaniline to ethylenediamine dihydrochloride is 1:1.

[0011] In some embodiments of this application, the reaction temperature is 200°C and the reaction time is 9 hours.

[0012] In some embodiments of this application, the solvent is water.

[0013] A carbon quantum dot, prepared using the method described above.

[0014] The application of the carbon quantum dots in the detection of rifampicin.

[0015] A method for detecting rifampicin concentration, comprising:

[0016] Prepare a first solution, wherein the first solution is an aqueous solution of carbon quantum dots;

[0017] The first solution was irradiated with excitation light at 381 nm, and the fluorescence intensity f emitted by the first solution at a wavelength of 519 nm was obtained. 381 ;

[0018] The first solution was irradiated with excitation light at 443 nm, and the fluorescence intensity f emitted by the first solution at a wavelength of 519 nm was obtained. 443 ;

[0019] The first solution is mixed with the solution to be tested to obtain a second solution;

[0020] The second solution was irradiated with excitation light at 381 nm, and the fluorescence intensity F emitted by the second solution at a wavelength of 519 nm was obtained. 381 ;

[0021] The second solution was irradiated with excitation light at 443 nm, and the fluorescence intensity F emitted by the second solution at a wavelength of 519 nm was obtained. 443 ;

[0022] Based on f 381 / f 443 and F 381 / F 443 Determine the concentration of rifampicin in the test solution.

[0023] The beneficial effects of this invention are as follows:

[0024] The carbon quantum dots provided by this invention have two emission centers, with excitation wavelengths of 381 nm and 443 nm corresponding to the two emission centers, and an emission wavelength of 519 nm for both. In the PLE spectrum of the carbon quantum dots, the intensities at 381 nm and 443 nm are respectively F 381 and F443 When the carbon quantum dots and RIF are mixed, F 381 and F 443 All gradually decreased, and as the RIF concentration increased, F... 381 and F 443 The rate of decline is also increasing, but F 443 The descent speed is faster than F 381 The rate of decrease. Therefore, the carbon quantum dots of this invention can be controlled by the bimodal ratio, i.e., F... 381 / F 443 The detection of rifampicin concentration can be achieved by using the bimodal ratio, which can improve the detection accuracy of rifampicin by carbon quantum dots and reduce the detection limit of rifampicin.

[0025] Furthermore, compared to other carbon quantum dots that can detect rifampicin concentration through bimodal ratio, the carbon quantum dots of this invention, after being mixed with rifampicin, exhibit F... 381 The reduction amount and F 443 The reduction amounts are more significantly different, which makes the carbon quantum dots of the present invention have higher detection accuracy and lower detection limit for rifampicin. Attached Figure Description

[0026] Figure 1 This is a TEM image of carbon quantum dots in an embodiment of the present invention;

[0027] Figure 2 This is a particle size distribution diagram of carbon quantum dots in an embodiment of the present invention;

[0028] Figure 3 The image shows the XRD pattern of carbon quantum dots in an embodiment of the present invention.

[0029] Figure 4 The image shows the AFM diagram of carbon quantum dots in an embodiment of the present invention.

[0030] Figure 5 The FT-IR spectrum of carbon quantum dots in this embodiment of the invention;

[0031] Figure 6 The XPS spectrum of carbon quantum dots in an embodiment of the present invention;

[0032] Figure 7 The high-resolution XPS spectrum of carbon quantum dots in this embodiment of the invention;

[0033] Figure 8 The UV-vis absorption spectrum, PL spectrum, and PLE spectrum of carbon quantum dots in the embodiments of the present invention are shown below.

[0034] Figure 9 The PL spectra of carbon quantum dots under different wavelengths of excitation light in the embodiments of the present invention;

[0035] Figure 10 The EEM spectrum of carbon quantum dots in this embodiment of the invention;

[0036] Figure 11 Fluorescence stability test of carbon quantum dots in embodiments of the present invention Figure 1 ;

[0037] Figure 12 Fluorescence stability test of carbon quantum dots in embodiments of the present invention Figure 2 ;

[0038] Figure 13 The PLE spectra of carbon quantum dots and different concentrations of RIF in this embodiment of the invention are shown.

[0039] Figure 14 F in the embodiments of the present invention 381 / F 443 Functional relationship between RIF concentration and Figure 1 ;

[0040] Figure 15 F in the embodiments of the present invention 381 / F 443 Functional relationship between RIF concentration and Figure 2 ;

[0041] Figure 16 The UV-vis absorption spectra of carbon quantum dots, UV-vis absorption spectra of RIF, theoretical UV-vis absorption spectra of carbon quantum dots and RIF, and actual UV-vis absorption spectra of carbon quantum dots and RIF are shown in the embodiments of the present invention.

[0042] Figure 17 The PL spectrum, PLE spectrum, and UV-vis absorption spectrum of carbon quantum dots are shown in the embodiments of the present invention.

[0043] Figure 18 The fluorescence decay curves of carbon quantum dots before and after mixing with RIF are shown in the embodiments of the present invention.

[0044] Figure 19 This is a test diagram showing the specificity of carbon quantum dots for RIF detection in an embodiment of the present invention. Detailed Implementation

[0045] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0046] Example:

[0047] This embodiment first provides a carbon quantum dot, the preparation method of which includes the following steps: 0.4 g of 2-hydroxyaniline (2-aminophenol) and 0.4 g of ethylenediamine hydrochloride (EDA·2HCl) are mixed in 30 mL of deionized water and ultrasonically stirred, then transferred to a reaction vessel and reacted at 200 °C for 9 h. After the reaction is completed and cooled to room temperature, the solution obtained from the reaction is filtered through a filter with a pore diameter of 0.22 μm, and then reaction byproducts are removed by centrifugation (centrifugation speed 8000 rpm, centrifugation time 30 min) and dialysis (dialysis membrane molecular weight cutoff 1000 Da, dialysis time 24 h), and then the carbon quantum dots are obtained by rotary evaporation.

[0048] like Figure 1 As shown, the carbon quantum dots are uniformly distributed spherical nanoparticles with no obvious agglomeration, and their lattice spacing is 0.21 nm, matching the (100) crystal plane of graphite carbon. Figure 2 As shown, the carbon quantum dots have a particle size distribution between 2 nm and 6 nm, with an average particle size of approximately 3.92 nm. Figure 3 As shown, the XRD pattern of the carbon quantum dots shows a relatively broad diffraction peak at 22.6°, corresponding to the (002) crystal plane of graphitic carbon. Figure 4 As shown, the average thickness of the carbon quantum dots is approximately 1.33 nm, indicating that they have multiple graphene-like layers.

[0049] like Figure 5 As shown, in the FT-IR spectrum of the carbon quantum dots, at 3100 cm⁻¹ -1 -3500cm -1 There is a relatively broad absorption band between them, corresponding to the characteristic stretching vibration of OH or the vibration of NH; 2963 cm⁻¹ -1 -3085cm -1 The peak between these points corresponds to the stretching vibration of CH; 1602 cm⁻¹ -1 The peak at 1510 cm⁻¹ corresponds to C=O. -1 The peak at 1352 cm corresponds to C=C. -1 The peak at this location corresponds to C=N, 1039 cm⁻¹ -1 The peak at 804 cm⁻¹ corresponds to CO. -1 The peak at that location corresponds to C-Cl.

[0050] like Figure 6As shown, in the XPS spectrum of the carbon quantum dots, the peak at 284.1 eV corresponds to C 1s, the peak at 399.1 eV corresponds to N 1s, the peak at 532.1 eV corresponds to O 1s, and the peak at 197.4 eV corresponds to Cl 2p; based on Figure 6 Measurements showed that the carbon quantum dots contained 63.28% C, 17.24% N, 14.44% O, and 5.04% Cl. Further combination... Figure 7 In the high-resolution C 1s spectrum, the peak at 283.42 eV corresponds to C=C / CC, the peak at 284.13 eV corresponds to CN / CO, and the peak at 285.23 eV corresponds to C=O / C=N; in the high-resolution N 1s spectrum, the peak at 398.35 eV corresponds to CNC, and the peak at 400.25 eV corresponds to NH; in the high-resolution O 1s spectrum, the peak at 530.5 eV corresponds to C=O, and the peak at 531.7 eV corresponds to CO; in the high-resolution Cl 2p spectrum, the peak at 196.9 eV corresponds to Cl 2p. 3 / 2 The peak at 198.2 eV corresponds to the Cl 2p orbital, and the peak at 198.8 eV corresponds to the Cl 2p orbital. 1 / 2 .

[0051] like Figure 8 As shown, in the UV-vis absorption spectrum of the carbon quantum dots, the absorption peak at 235 nm corresponds to C=C. The transition, with an absorption peak at 293 nm corresponding to the CO / C=O transition. The absorption band between 350 nm and 450 nm corresponds to electronic transitions of defect-related surface states. For example... Figure 8 As shown in the middle inset, the aqueous solution of the carbon quantum dots emits green fluorescence under ultraviolet light and appears light brownish-yellow under sunlight. The PLE and PL spectra of the carbon quantum dots show that they have two excitation wavelengths at 381 nm and 443 nm, and an emission wavelength of 519 nm. Meanwhile, as... Figure 9 As shown, as the excitation wavelength increases from 370 nm to 470 nm, the emission wavelength of the carbon quantum dots remains almost unchanged. Further as... Figure 10 As shown, the carbon quantum dot has two emission centers, with excitation wavelengths of 381 nm and 443 nm corresponding to the two emission centers, and an emission wavelength of 519 nm for both.

[0052] like Figure 11 As shown in the attached figure on the left, after 24 hours of ultraviolet light irradiation, the fluorescence intensity emitted by the carbon quantum dots under 381 nm excitation light and under 443 nm excitation light showed almost no decrease; Figure 11As shown in the middle figure, after 30 days of storage, the fluorescence intensity emitted by the carbon quantum dots under 381 nm excitation light and under 443 nm excitation light showed almost no decrease; Figure 11 As shown in the attached figure on the right, the fluorescence intensity emitted by the carbon quantum dots under 381 nm excitation light and under 443 nm excitation light is almost completely preserved even in a 2.2 mol / L NaCl solution; Figure 12 As shown, the fluorescence intensity of the carbon quantum dots remains almost unchanged within a temperature range of 15°C to 65°C. This demonstrates that the carbon quantum dots possess extremely high physical and chemical stability.

[0053] In the PLE spectrum of the carbon quantum dots, the intensities at 381 nm and 443 nm are F0 and F1, respectively. 381 and F 443 .like Figure 13 As shown, when the carbon quantum dots and RIF are mixed, F 381 and F 443 All gradually decreased, and as the RIF concentration increased, F... 381 and F 443 The rate of decline is also increasing, but F 443 The descent speed is faster than F 381 The rate of descent. Based on this, further combining... Figure 14 and Figure 15 F 381 / F 443 The concentration of F increases with increasing RIF concentration. When the RIF concentration is in the range of 0.058 μM-35 μM, F... 381 / F 443 There is a good linear relationship between the concentration of RIF and the concentration of RIF (R0). 2 =0.9976), the corresponding linear relationship is y=0.0047x+1.4679, where x represents the RIF concentration and y represents F 381 / F 443 This demonstrates that the carbon quantum dots can be used for the detection of RIF. According to the 3σ / k method, the detection limit (LOD) of the carbon quantum dots for RIF is 58 nM, which is significantly lower than that of most existing RIF detection reagents.

[0054] Further as Figure 19 As shown, after the carbon quantum dots are mixed with RIF, F 381 and F 443 A significant decrease occurred ( Figure 19 As shown in Blank (in the middle). Based on this, the carbon quantum dots and interfering substances are mixed separately, F 381 and F 443 Very little change ( Figure 19(As shown in the Interference diagram), the carbon quantum dots, RIF, and interfering substances are mixed together, F 381 and F 443 A significant decrease occurred ( Figure 19 As shown in the Interference+RIF diagram, this demonstrates that the carbon quantum dots exhibit excellent detection specificity for RIF. The interfering substance is Co. 2+ Ba 2+ Zr 4+ Mg 2+ Cd 2+ Na + Eu 3+ Pb 2+ Mn 2+ Ca 2 + Zn 2+ Cl - BO3 3- SO4 2- SO3 2- HCO3 - NO3 - One of the following: alanine (Ala), serine (Ser), L-asparagine (Asn), L-cysteine ​​(Cys), glycine (Gly), glucose (Glu), and dopamine (Dop).

[0055] Based on the above findings, this embodiment further provides a method for detecting rifampicin concentration, comprising the following steps:

[0056] Step 101: Prepare the first solution, which is an aqueous solution of carbon quantum dots;

[0057] Step 102: Irradiate the first solution with 381nm excitation light and obtain the fluorescence intensity f of the first solution at a wavelength of 519nm. 381 ;

[0058] Step 103: Irradiate the first solution with excitation light at 443 nm and obtain the fluorescence intensity f of the first solution at a wavelength of 519 nm. 443 ;

[0059] Step 104: Mix the first solution with the solution to be tested to obtain the second solution;

[0060] Step 105: Irradiate the second solution with excitation light at 381 nm and obtain the fluorescence intensity F of the second solution at a wavelength of 519 nm. 381 ;

[0061] Step 106: Irradiate the second solution with excitation light at 443 nm and obtain the fluorescence intensity F of the second solution at a wavelength of 519 nm. 443 ;

[0062] Step 107: Based on f 381 / f 443 and F 381 / F 443 Determine the concentration of rifampicin in the test solution.

[0063] Regarding the detection mechanism of RIF by carbon quantum dots, the following research was conducted in this embodiment.

[0064] Firstly, as Figure 16 As shown, the actual UV-vis absorption spectrum of the carbon quantum dots and RIF mixed solution did not produce any new absorption peaks compared to the theoretical UV-vis absorption spectrum, and the two are in high agreement, indicating that no new complex was formed between the carbon quantum dots and RIF. Figure 17 As shown, the UV-vis absorption spectrum of RIF and the PL and PLE spectra of the carbon quantum dots show significant overlap, indicating that the detection mechanism of RIF by the carbon quantum dots may originate from the combined effect of internal filtering effect (IFE) and fluorescence resonance energy transfer (FRET). Further... Figure 18 As shown, after the carbon quantum dots and RIF are mixed, their fluorescence lifetime under 381nm excitation light decreases from 3.68ns to 2.66ns, and under 443nm excitation light, their fluorescence lifetime decreases from 3.76ns to 3.02ns, confirming that IFE and FRET occur simultaneously.

[0065] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0066] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing carbon quantum dots, characterized in that, include: 2-hydroxyaniline and ethylenediamine dihydrochloride are mixed in a solvent and then transferred to a reaction vessel for heating to obtain the carbon quantum dots.

2. The method for preparing carbon quantum dots according to claim 1, characterized in that, The mass ratio of 2-hydroxyaniline to ethylenediamine dihydrochloride is 1:

1.

3. The method for preparing carbon quantum dots according to claim 2, characterized in that, The reaction temperature was 200℃ and the reaction time was 9 hours.

4. The method for preparing carbon quantum dots according to claim 3, characterized in that, The solvent is water.

5. A carbon quantum dot, characterized in that, The carbon quantum dots were prepared using the method described in any one of claims 1-4.

6. The application of carbon quantum dots as described in claim 5 in the detection of rifampicin.

7. A method for detecting rifampicin concentration, characterized in that, include: Prepare a first solution, wherein the first solution is an aqueous solution of carbon quantum dots as described in claim 5; The first solution was irradiated with excitation light at 381 nm, and the fluorescence intensity f emitted by the first solution at a wavelength of 519 nm was obtained. 381 ; The first solution was irradiated with excitation light at 443 nm, and the fluorescence intensity f emitted by the first solution at a wavelength of 519 nm was obtained. 443 ; The first solution is mixed with the solution to be tested to obtain a second solution; The second solution was irradiated with excitation light at 381 nm, and the fluorescence intensity F emitted by the second solution at a wavelength of 519 nm was obtained. 381 ; The second solution was irradiated with excitation light at 443 nm, and the fluorescence intensity F emitted by the second solution at a wavelength of 519 nm was obtained. 443 ; Based on f 381 / f 443 and F 381 / F 443 Determine the concentration of rifampicin in the test solution.

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