Preparation of B, N co-doped dual-emission ratio type fluorescent carbon quantum dot fluorescent probe and application of B, N co-doped dual-emission ratio type fluorescent carbon quantum dot fluorescent probe in atrazine detection

Abstract

The invention discloses preparation of a B and N co-doped dual-emission ratio type fluorescent carbon quantum dot fluorescent probe and application of the B and N co-doped dual-emission ratio type fluorescent carbon quantum dot fluorescent probe in atrazine detection, and belongs to the technical field of nano functional materials and fluorescence analysis and detection. When the fluorescent carbon quantum dot fluorescent probe is prepared, the optimal reaction temperature is 160 DEG C, the optimal heating time is 5 hours, the optimal raw material ratio of 3-CPBA to PPD is 2: 1, and the optimal pH is 8. The concentration range of the detected atrazine is 0.15-600 [mu] g / L, the I660 / I380 ratio and the concentration of the atrazine show a good linear relationship, the linear fitting equation is y = 0.004 [atrazine] + 0.29, and the detection limit is 0.187 [mu] g / L. 3.5 min is selected as the detection time, so that both efficiency and accuracy can be considered. The probe has a specific recognition capability on atrazine in actual sample detection, and has a good detection effect. The method has great significance in the field of atrazine detection.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterials and fluorescence analysis and detection technology, and particularly relates to a B, N co-doped dual-emission ratio carbon quantum dot fluorescent probe, its preparation method and its application in the detection of the triazine herbicide atrazine. Background Technology

[0002] Atrazine, a triazine selective herbicide, is one of the most widely used herbicides globally, extensively applied to control weeds in corn, sorghum, sugarcane, wheat, and public green spaces. Due to its extremely high environmental stability, persistence, and high migration rate, atrazine has become a typical persistent organic pollutant (POPs). Therefore, establishing a rapid, sensitive, low-cost atrazine detection technology suitable for field monitoring is of significant environmental and food safety importance. Currently, traditional atrazine detection techniques include gas chromatography (GC), high-performance liquid chromatography (HPLC), and mass spectrometry (GC-MS, LC-MS / MS). While these methods offer high sensitivity, they suffer from significant drawbacks such as expensive equipment, complex operation, long detection times, time-consuming sample pretreatment, and high dependence on specialized personnel, making them unsuitable for rapid monitoring at the grassroots level and in field environments. Therefore, developing a novel sensing material that is simple to operate, rapid in detection, and exhibits high selectivity and sensitivity for atrazine has become a research hotspot.

[0003] In recent years, fluorescence detection methods based on nanomaterials have gradually attracted attention. Among them, carbon quantum dots (CQDs) have become an important material for constructing fluorescent probes due to their good water solubility, stable fluorescence, low toxicity, ease of synthesis, and ease of modification. However, most existing CQDs are single-emission, and their fluorescence signals are easily affected by probe concentration, instrument fluctuations, and complex matrix backgrounds, leading to a decrease in quantitative accuracy.

[0004] In contrast, ratiometric dual-emission fluorescent probes self-calibrate by the intensity ratio of the two emission peaks, effectively compensating for errors caused by light source, concentration, instrument drift, and environmental background. This makes them one of the most promising fluorescence detection strategies in recent years. However, carbon quantum dot materials capable of generating stable dual emission under single excitation conditions and exhibiting high selectivity for atrazine are still relatively few, and shortcomings remain in preparation methods, dual-emission mechanisms, and application stability.

[0005] Therefore, there is an urgent need to develop a novel carbon quantum dot fluorescent probe that is structurally stable, has clear dual emission, is sensitive to atrazine, and has ratio self-calibration capability, in order to solve the technical bottlenecks in atrazine detection, such as insufficient sensitivity, strong matrix interference, and high equipment dependence. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a B / N co-doped dual-emission ratiometric carbon quantum dot fluorescent probe. This novel carbon quantum dot fluorescent probe exhibits structural stability, well-defined dual emission, sensitive response to atrazine, and ratio self-calibration capability, effectively solving the problems of insufficient sensitivity, strong matrix interference, and high equipment dependence in the field of atrazine detection.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: One objective of this invention is to provide a method for preparing a B, N co-doped dual-emission ratio carbon quantum dot fluorescent probe, comprising the following steps: S1. Dissolve a boron-containing organic acid source and an aromatic amine source in an organic solvent to obtain a mixed solution; S2. Add an alkaline solution to the mixed solution to adjust the pH to 7.0-9.0, and after dispersion treatment, carry out a hydrothermal reaction to obtain the precursor product; S3. Add boric acid solution to the precursor product and allow it to stand; S4. After microporous membrane filtration, dialysis bag dialysis, and nitrogen blowing concentration to remove impurities, the B, N co-doped dual-emission ratio carbon quantum dot fluorescent probe is obtained.

[0008] Preferably, the boron-containing organic acid source includes 3-carboxyphenylboronic acid, and the aromatic amine source includes p-phenylenediamine, with a mass ratio of (1.5:1) to (2.5:1).

[0009] Preferably, the organic solvent includes formamide and anhydrous ethanol in a volume ratio of (1.5-2.5):1.

[0010] Preferably, the alkaline solution comprises an aqueous ammonia solution.

[0011] Preferably, the dispersion treatment includes ultrasonic treatment for 10-20 minutes.

[0012] Preferably, the hydrothermal reaction is carried out at a temperature of 150-170°C for 4-6 hours.

[0013] Preferably, the concentration of the boric acid solution is 0.5-1.5 g / L, and the settling time is 22-26 hours.

[0014] The second objective of this invention is to provide a B, N co-doped dual-emission ratio carbon quantum dot fluorescent probe, which is prepared using the aforementioned preparation method.

[0015] A third objective of this invention is to provide a method for detecting atrazine, including the step of using the aforementioned B, N co-doped dual-emission ratio carbon quantum dot fluorescent detector.

[0016] The fourth objective of this invention is to provide the application of the preparation method, the B, N co-doped dual-emission ratio carbon quantum dot fluorescent probe, or the detection method in the detection of atrazine.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The optimal reaction temperature for preparing the B / N co-doped dual-emission ratio fluorescent carbon quantum dot probe of this invention is 160℃, the optimal heating time is 5 h, the optimal raw material ratio is 3-CPBA:PPD=2:1, and the optimal pH is 8. Its detection range for atrazine concentration is 0.15-600 μg / L, and the I660 / I380 ratio shows a good linear relationship with the atrazine concentration. The linear fitting equation is: y=0.004[atrazine]+0.29, and the detection limit is 0.187 μg / L. Choosing 3.5 min as the detection time balances efficiency and accuracy. It exhibits specific recognition ability for atrazine in actual sample detection.

[0018] 2. The B, N co-doped dual-emission ratiometric carbon quantum dot fluorescent probe of this invention is a novel carbon quantum dot fluorescent probe with stable structure, well-defined dual emission, sensitive response to atrazine, and ratio self-calibration capability. It can effectively solve the problems of insufficient sensitivity, strong matrix interference, and high equipment dependence in the field of atrazine detection, and is of great significance in the field of atrazine detection. Attached Figure Description

[0019] Figure 1 The microstructure analysis results of B,NCQDs in Example 1 of this invention are as follows: (a) TEM image; (b) particle size distribution histogram.

[0020] Figure 2 This is an orthogonal experimental diagram of the fluorescence performance of B,NCQDs in Example 2 of the present invention.

[0021] Figure 3 The graphs shown are linear fluorescence spectra (a) and fitted curves (b) of the binding of B,NCQDs and atrazine in Example 3 of this invention.

[0022] Figure 4 This is the result of the investigation on the interaction duration between B, NCQDs and atrazine in Example 4 of the present invention.

[0023] Figure 5 This is a diagram showing the interference of some common interfering substances on fluorescence intensity in Example 5 of the present invention. Detailed Implementation

[0024] The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the invention. Any modifications or substitutions made to the methods, steps, or conditions of the present invention without departing from the spirit and essence of the invention are within the scope of the invention. Unless otherwise specified, the products and equipment used in the following embodiments are commercially available, and the methods used are consistent with conventional methods unless otherwise specified.

[0025] The main contents of this invention are as follows: 1. Preparation of B, N co-doped dual-emission ratiometric carbon quantum dot fluorescent probes 0.4 g of 3-carboxyphenylboronic acid (3-CPBA) and 0.2 g of p-phenylenediamine (PPD) were weighed and dissolved in 20 mL of formamide, followed by the addition of 10 mL of anhydrous ethanol to form a homogeneous mixture. 0.1 M ammonia was slowly added dropwise to adjust the pH of the solution to approximately 8.0. After sonication for 15 min, the resulting mixture was transferred to a stainless steel hydrothermal reactor lined with a 100 mL polytetrafluoroethylene (PTFE) bushing and heated at 160 °C for 5 h. After the reaction was completed and cooled to room temperature, 2 mL of a 1 g / L boric acid (BA) solution was added to the resulting dark-colored solution and allowed to stand for 24 h to further dope and rearrange the boron. Subsequently, a 0.22 μm microporous membrane was used to remove large molecular particles and insoluble matter, and the filtrate was dialyzed using a 1000 Da dialysis bag to remove unreacted precursors and small molecule impurities. The dialyzed solution was concentrated using nitrogen blowing to remove residual organic solvents. Finally, the concentrated quantum dot solution was diluted to an absorbance of approximately 0.40 at its maximum absorption wavelength and stored at 4°C for later use. It was named B,NCQDs.

[0026] 2. Establishment of a detection method for atrazine Add 0.4 mL of atrazine at different concentrations (0, 0.05, 0.1, 0.15, 0.5, 1, 50, 100, 300, 500, 600, 800, 1000, 1200 μg / L) to 3.2 mL of prepared probe solution, and add 0.1 M sodium citrate buffer to adjust the pH to 5. Mix and shake at room temperature for 3-4 min, and record the fluorescence spectrum changes at 380 nm and 660 nm. Excite the slit for 5 nm and illuminate the slit for 10 nm to obtain the fluorescence intensity. Finally, fit the linear relationship with I660 / I380 as the ordinate and atrazine concentration as the abscissa. Repeat the process 5 times.

[0027] 3. Determination of atrazine content 10g of soil and fruit homogenate were added to 10mL of a mixture of acetonitrile and water (v / v = 5:5). The mixture was centrifuged at 5000 rpm for 5 min, and the supernatant was filtered through a 0.22 μm organic filter membrane. 10mL of water sample was directly added to a centrifuge tube and centrifuged at 5000 rpm for 5 min. The supernatant was filtered through a 0.22 μm organic filter membrane. 0.4mL of the supernatant was added to 3.2mL of the prepared probe solution, and 0.1M sodium citrate buffer was added to adjust the pH to 5. After mixing and shaking at room temperature for 3-4 min, the fluorescence spectra at 380 nm and 660 nm were recorded. The concentration was determined using a standard curve.

[0028] The technical solution of the present invention will be further described in detail below with reference to the embodiments.

[0029] Example 1: Preparation of B, N co-doped dual-emission ratiometric carbon quantum dot fluorescent probe Weigh 0.4 g of 3-carboxyphenylboronic acid (3-CPBA, Shanghai Maclean Biochemical Technology Co., Ltd., C7H7BO4, 99%, CAS 25487-66-5) and 0.2 g of p-phenylenediamine (PPD, Shanghai Maclean Biochemical Technology Co., Ltd., C6H8N2, 98%, CAS 106-50-3), dissolve them in 20 mL of formamide (Shanghai Maclean Biochemical Technology Co., Ltd., CH3NO, 99%, CAS 75-12-7), and then add 10 mL of anhydrous ethanol to form a homogeneous mixture. Slowly add 0.1 M ammonia to adjust the pH of the solution to approximately 8.0. After sonication for 15 min, transfer the resulting mixture to a stainless steel hydrothermal reactor lined with a 100 mL polytetrafluoroethylene (PTFE) bushing, and heat at 160 °C for 5 h. After the reaction was completed and cooled to room temperature, 2 mL of a 1 g / L boric acid solution (BA, Shanghai Maclean Biochemical Technology Co., Ltd., H3BO3, ≥99.8%, CAS 10043-35-3) was added to the resulting dark-colored solution and allowed to stand for 24 h to complete further doping and surface rearrangement of boron. Subsequently, a 0.22 μm microporous membrane was used to remove large molecular particles and insoluble matter, and the filtrate was dialyzed using a 1000 Da dialysis bag to remove unreacted precursors and small molecule impurities. The dialyzed solution was concentrated using nitrogen blowing to remove residual organic solvents. Finally, the concentrated quantum dot solution was diluted to an absorbance of approximately 0.40 at its maximum absorption wavelength and stored at 4 °C for later use.

[0030] The prepared carbon quantum dots were characterized by TEM analysis, and the results are as follows: Figure 1As shown, the prepared B,NCQDs exhibit excellent dispersibility in water with no agglomeration. The particle size is concentrated in the range of 8.72-13.54 nm, with an average particle size of 10.10 nm, which corresponds to the particle size measured by the nanoparticle size analyzer.

[0031] Example 2 Optimization of Synthesis Conditions To obtain the optimal fluorescence intensity of B,NCQDs, the reaction temperature, reaction time, raw material ratio, and pH were optimized. These factors are crucial for controlling the polycondensation and carbonization of CQDs. Except for the factor under investigation, all other conditions were kept consistent. Considering the above factors, a four-factor, four-level orthogonal experiment was conducted on B,NCQDs, as shown in Table 1. The reaction temperatures were (140℃, 160℃, 180℃, 200℃), the reaction times were (4h, 5h, 6h, 7h), the raw material ratios were (1:1, 2:1, 3:1, 4:1), and the pH was (6, 7, 8, 9).

[0032] Table 1. Orthogonal experimental design table for optimizing experimental conditions

[0033] Figure 2 To compare the fluorescence intensity of the material after binding with atrazine under different experimental conditions during the preparation process, it was found that the optimal reaction temperature was 160℃, the heating time was 5 h, the raw material ratio was 3-CPBA:PPD=2:1, and the pH was 8, resulting in the highest fluorescence intensity ratio of B and NCQDs.

[0034] Example 3: Construction of a fluorescence detection method for atrazine Using the fluorescence intensity ratio (I660 / I380) without atrazine as the initial value, the change in the ratio after adding atrazine was plotted on the ordinate and the concentration on the abscissa. Figure 3 a represents the change in fluorescence intensity after the addition of atrazine. Figure 3 b represents the linear relationship after adding different concentrations of atrazine. The results show that the concentration range of atrazine detected by the prepared fluorescent carbon quantum dots is 0.15-600 μg / L. The I660 / I380 ratio shows a good linear relationship with the atrazine concentration (r2=0.9929), and the linear fitting equation is: y=0.004[atrazine]+0.29, with a detection limit of 0.187 μg / L.

[0035] Example 4B: Investigation of the interaction time between NCQDs and atrazine As shown in Figure 4, within a short interaction time (2 min), the fluorescence I660 / I380 intensity ratio increases rapidly. With the interaction time extended to 3.5 min, the fluorescence I660 / I380 ratio gradually increases and reaches a stable value, indicating that the binding of the probe to atrazine tends to stabilize. Further extending the interaction time did not significantly change the fluorescence signal, indicating that the interaction is essentially completed within 3.5 min. This demonstrates that choosing 3.5 min as the detection time for the probe in this invention balances efficiency and accuracy.

[0036] Example 5: Results of Interference Measurement The selective detection results of atrazine by B,NCQDs fluorescent probes are as follows: Figure 5 As shown (interferant concentration: atrazine concentration = 10:1), the addition of atrazine to B,NCQDs significantly enhanced the I660 / I380 fluorescence ratio, while the change in the fluorescence ratio for interferants was relatively weak. This further confirms the probe's specific recognition ability for atrazine in actual sample detection, providing a reliable basis for future applications.

[0037] Example 6: Determination of Atrazine Residual Concentration The residual concentration of atrazine in water, soil, and fruit samples was determined using the established detection method. Different concentrations of atrazine solution were added to the homogenates of water, soil, and fruit, and the samples were left at room temperature for 1 hour to allow for analyte absorption. For soil and fruit homogenates, 10 g of each was added to 10 mL of a mixture of acetonitrile and water (v / v = 5:5). The mixture was centrifuged at 5000 r / min for 5 min, and the supernatant was filtered through a 0.22 μm organic filter membrane. For water samples, 10 mL was directly centrifuged at 5000 r / min for 5 min, and the supernatant was filtered through a 0.22 μm organic filter membrane. 0.4 mL of the supernatant was added to 3.2 mL of the prepared probe solution, and 0.1 M sodium citrate buffer was added to adjust the pH to 5. After mixing and shaking at room temperature for 3-4 min, the fluorescence spectra at 380 nm and 660 nm were recorded. The data were then used to derive the measured concentration using a standard curve. The recovery rate and relative standard deviation (RSD) were calculated to examine the accuracy and precision of the method, and the experiment was repeated 5 times. The results are shown in Table 2.

[0038] Table 2. Average recoveries and relative standard deviations (RSD) of atrazine in spiked samples.

[0039] Table 2 shows that the rapid residue detection method established based on the present invention has an average recovery rate of 94.6%~105.75% for the added samples and a relative standard deviation of 1.65%~5.65%, which can be used for the detection of actual samples.

[0040] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a B, N co-doped dual-emission ratio type carbon quantum dot fluorescent probe, characterized in that, The method comprises the following steps: S1. Dissolving a boron-containing organic acid source and an aromatic amine source in an organic solvent to obtain a mixed solution; S2. Adding a basic solution to the mixed solution to adjust the pH to 7.0-9.0, and then performing a dispersion treatment, and then performing a hydrothermal reaction to obtain a precursor product; S3. Adding a boric acid solution to the precursor product and performing a standing treatment; S4. Filtering through a microporous filter membrane, dialyzing through a dialysis bag, and concentrating and removing impurities through nitrogen blowing to obtain the B, N co-doped double-emission-ratio carbon quantum dot fluorescent probe.

2. The production method according to claim 1, characterized by, The boron-containing organic acid source comprises 3-carboxyphenylboronic acid, and the aromatic amine source comprises p-phenylenediamine, and the mass ratio of the two is (1.5:1)-(2.5:1).

3. The production method according to claim 2, characterized by, The organic solvent comprises formamide and anhydrous ethanol, and the volume ratio of the two is (1.5-2.5):

1.

4. The production method according to claim 3, characterized by, The basic solution comprises an ammonia solution.

5. The preparation method according to claim 4, characterized in that, The dispersion treatment comprises ultrasonic treatment, and the time is 10-20 minutes.

6. The production method according to claim 5, wherein The temperature of the hydrothermal reaction is 150-170°C, and the time is 4-6 hours.

7. The production method according to claim 6, wherein The concentration of the boric acid solution is 0.5-1.5 g / L, and the standing treatment time is 22-26 hours.

8. A B, N co-doped dual-emission ratio type carbon quantum dot fluorescent probe, characterized in that, The B, N co-doped double-emission-ratio carbon quantum dot fluorescent probe is prepared by using the preparation method of any one of claims 1-7.

9. A method of detecting atrazine, characterized by, The method comprises the steps of using the B, N co-doped double-emission-ratio carbon quantum dot fluorescent probe of claim 8.

10. Application of the preparation method of any one of claims 1-7, the B, N co-doped double-emission-ratio carbon quantum dot fluorescent probe of claim 8, or the detection method of claim 9 in atrazine detection.

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