Organic cocrystal TCNB-TODI and its preparation method and application

Abstract

The present invention discloses the field of tetracycline detection technology, specifically to an organic cocrystal TCNB-TODI and its preparation method and application. The organic cocrystal uses 1,2,4,5-tetracyanobenzene as an acceptor molecule and dimethylbiphenyl diisocyanate as a donor molecule, and is prepared by a liquid-assisted grinding method. During the preparation, an appropriate amount of 1,2,4,5-tetracyanobenzene and dimethylbiphenyl diisocyanate are placed in a mortar, an acetonitrile solution is added dropwise, and the mixture is wet-ground for 10 minutes until the mixture becomes a yellow powder. The yellow powder obtained by grinding is placed in a 75°C oven and dried for 24 hours. The present invention provides a new fluorescence signal analysis method for rapid and sensitive detection of TC in food residues. Compared with traditional detection methods such as chromatography and surface-enhanced Raman spectroscopy, the fluorescence signal analysis method of the present invention has multiple advantages such as a wide linear range, low cost, short time consumption, and simple operation.

Description

Technical Field

[0001] The present invention relates to the technical field of tetracycline detection, and in particular to an organic cocrystal TCNB-TODI and a preparation method and application thereof. Background Art

[0002] Tetracycline (TC) is a broad-spectrum antibiotic derived from Streptomyces. Its notable characteristics include potent antibacterial activity, good oral absorption, low toxicity, and cost-effectiveness. This antibiotic plays a key role in the prevention and treatment of bacterial diseases in animals and is also commonly used as a growth promoter. However, if TC is overused in animal husbandry for economic gain, its accumulation in animal-derived foods will pose a significant threat to human health. Long-term consumption of foods containing TC residues can lead to a range of health problems, such as yellowing of teeth, gastrointestinal disorders, allergic reactions, and liver damage, and can also exacerbate bacterial resistance to antibiotics. Therefore, monitoring TC residues in animal products is crucial to ensuring food safety.

[0003] Traditional TC detection methods have high requirements for the precision of instruments, sample pretreatment process and the professional level of operators. In contrast, fluorescence analysis stands out for its unique advantages. It identifies substances and determines their content based on the position and intensity of the fluorescence spectrum of the substance. It is not only simple to operate and low-cost, but also has a fast response speed and can visualize the results. For example, Zhou Tong's team developed a fluorescence sensor based on nitrogen-doped carbon quantum dots. This method has high sensitivity and a detection limit of 89.26μg / L. Yin, Yang and others designed fluorescent probes with different ion ratios to analyze the presence of tetracycline. Their LODs were 11.8nmol / L and 0.07μmol / L, respectively, with excellent sensitivity. Thanks to the use of efficient sample pretreatment technology and highly sensitive instruments, these methods have good sensitivity, but they often consume more time and manpower.

[0004] In recent years, organic cocrystal functional materials have found promising applications in ferroelectric materials, optical waveguides, stimulus-responsive materials, and analytical detection due to their simple synthesis methods and easily tunable physicochemical properties. Unlike traditional chemical synthesis methods, the structural units of organic cocrystals are tightly assembled through non-covalent intermolecular interactions, such as hydrogen bonds, halogen bonds, charge transfer (CT), and π-π interactions. Because the strength of these non-covalent interactions in cocrystals is relatively weak (0.25 to 40 kcal / mol), the preparation of organic cocrystals avoids harsh experimental conditions such as high temperature and pressure, greatly simplifying the synthesis process. Summary of the Invention

[0005] To address the above problems, the present invention provides an organic cocrystal TCNB-TODI, a preparation method, and an application thereof. The organic cocrystal exhibits fluorescence quenching behavior when in contact with tetracycline, providing a new fluorescence signal analysis method for rapid and sensitive detection of tetracycline residues.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] The organic cocrystal TCNB-TODI is prepared by a liquid-assisted grinding method using 1,2,4,5-tetracyanobenzene (TCNB, CAS: 712-74-3) as an acceptor molecule and dimethyldiphenyl diisocyanate (TODI) as a donor molecule.

[0008] The present invention also provides a method for preparing the organic cocrystal TCNB-TODI, comprising the following steps:

[0009] S1: Place 1,2,4,5-tetracyanobenzene (TCNB, CAS: 712-74-3) and dimethyldiphenyl diisocyanate (TODI) in a mortar at a molar ratio of 1:1, add acetonitrile solution dropwise, and grind for 10 min until the mixture becomes a yellow powder;

[0010] S2. Place the yellow powder obtained by grinding in an oven at 75°C and dry for 24 hours.

[0011] The organic cocrystal TCNB-TODI of the present invention can be used to prepare a fluorescent sensor. The fluorescent sensor has good selectivity and sensitivity for tetracycline, has a good linear relationship in the range of 10 to 160 μM, has a detection limit of 1.09 μM, and has a spiked recovery rate of between 100.77% and 105.61%.

[0012] When the fluorescence sensor based on organic cocrystal TCNB-TODI is used for detection, 1 g / L organic cocrystal TCNB-TODI solution is placed in the test solution, reacted for 16 minutes, and its fluorescence intensity is measured. Based on the linear relationship between the fluorescence intensity of organic cocrystal TCNB-TODI and the tetracycline concentration, the tetracycline concentration can be obtained.

[0013] The organic cocrystal of the present invention has an excitation wavelength of 348.0 nm and an emission wavelength of 510.8 nm. This organic cocrystal exhibits excellent selectivity and sensitivity for tetracycline, with a good linear relationship within the range of 10 to 160 μM, a detection limit of 1.09 μM, and a spike recovery rate between 100.77% and 105.61%. This provides a new fluorescence signal analysis method for the rapid and sensitive detection of tetracycline in food residues. Compared to traditional detection methods such as chromatography and surface-enhanced Raman spectroscopy, the fluorescence signal analysis method of the present invention offers multiple advantages, including a wide linear range, low cost, short processing time, and ease of operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0015] Figure 1 Schematic diagram of the synthesis of TCNB-TODI organic cocrystal.

[0016] Figure 2 Schematic diagram of the organic donor TODI, organic acceptor TCNB, and organic cocrystal TCNB-TODI powder under natural light and ultraviolet light irradiation.

[0017] Figure 3 This is the PXRD spectrum of the organic cocrystal TCNB-TODI.

[0018] Figure 4 This is the Fourier transform infrared spectrum of the organic cocrystal TCNB-TODI.

[0019] Figure 5 Transmission electron microscopy image of organic cocrystal TCNB-TODI.

[0020] Figure 6 This is the UV-visible absorption spectrum of the organic cocrystal TCNB-TODI.

[0021] Figure 7 This is the fluorescence spectrum of the organic cocrystal TCNB-TODI.

[0022] Figure 8 Schematic diagram of thermogravimetric analysis of organic cocrystal TCNB-TODI.

[0023] Figure 9 (A) XRD spectra of organic cocrystal TCNB-TODI from different batches; (B) fluorescence spectra of organic cocrystal TCNB-TODI from different batches.

[0024] Figure 10(A) XRD spectra of organic cocrystal TCNB-TODI placed for different times; (B) fluorescence spectra of organic cocrystal TCNB-TODI placed for different times.

[0025] Figure 11 (A) Effect of pH on the fluorescence intensity of the prepared organic cocrystal TCNB-TODI; (B) Changes in the fluorescence intensity of the organic cocrystal TCNB-TODI over time after the addition of TC.

[0026] Figure 12 (A) Relationship between the fluorescence intensity of TCNB-TODI and different TC concentrations; (B) Linear fitting diagram of TCNB-TODI for detecting TC.

[0027] Figure 13 (A) Ratio of the fluorescence intensity of the blank sample of organic cocrystal TCNB-TODI to the fluorescence intensity after adding different antibiotics; (B) Fluorescence intensity of the blank sample of organic cocrystal TCNB-TODI and after adding different antibiotics.

[0028] Figure 14 This is the anti-interference property of the organic cocrystal TCNB-TODI.

[0029] Figure 15 (A) Fluorescence spectrum of organic cocrystal TCNB-TODI; (B) UV-visible absorption spectra of different antibiotics. DETAILED DESCRIPTION

[0030] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several variations and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0031] Reagent parameters:

[0032] All reagents used in the following examples were purchased from commercial channels without further purification or other operations, including: 1,2,4,5-tetracyanobenzene (C 10 H2N4) purity 98%, the manufacturer is San Chemical Technology (Shanghai) Co., Ltd.; Tetracycline (C 22 H 24 N2O8) purity 98%, the manufacturer is Tianjin Ai (Shanghai) Chemical Industry Development Co., Ltd.; dimethyl diphenyl diisocyanate (C 16 H 12N2O2) purity 98%, manufacturer is San Chemical Technology (Shanghai) Co., Ltd.; acetone (CH3H6O) purity 98%, manufacturer is Chengdu Kelong Chemical Co., Ltd.; acetonitrile (CH3CN) is analytical grade.

[0033] Instrument parameters:

[0034] Fourier transform infrared spectrometer, model is Thermo Nicolet 365; UV-visible absorption spectrometer model is UV-2600; powder X-ray diffractometer model is YYRIII30; fluorescence spectrometer model is Agilent5J2-0022 model F-4700; thermogravimetric analyzer model is NETZSCH STA 449FS.

[0035] Example 1: Preparation of organic cocrystal

[0036] The target organic cocrystal was prepared by solution-assisted grinding: 1,2,4,5-tetracyanobenzene (TCNB, CAS: 712-74-3) was used as the acceptor molecule and dimethyldiphenyl diisocyanate (TODI) was used as the donor molecule. TCNB (0.1818 g, 1 mmol) and TODI (0.2697 g, 1 mmol) were placed in a mortar and approximately 1 mL of acetonitrile solution was added dropwise. After the two components were wet-ground for 10 minutes, the mixture turned into a yellow powder. The ground organic cocrystal was placed in a 75°C oven and dried for 24 hours to obtain an organic cocrystal (TCNB-TODI) (e.g. Figure 1 shown).

[0037] Under natural light, TODI is a white powder, TCNB is a light pink powder, and the organic cocrystal TCNB-TODI is a yellow powder. Under ultraviolet light, TODI and TCNB do not fluoresce, while the organic cocrystal TCNQ-TODI emits strong yellow fluorescence (e.g. Figure 2 shown).

[0038] Example 2: Characterization of organic cocrystal TCNB-TODI

[0039] In order to further study its luminescence properties and intrinsic luminescence mechanism, the organic cocrystal compound TCNB-TODI was characterized by various characterization techniques including powder X-ray diffraction, ultraviolet absorption spectroscopy, fluorescence spectroscopy and infrared spectroscopy.

[0040] The prepared organic co-crystal TCNB-TODI and its monomer components were subjected to X-ray powder diffraction (PXRD) test (such as Figure 4(as shown), we can observe that the diffraction pattern of TCNB shows its unique crystal diffraction peaks at 14.0°, 18.5°, 22.5°, 30.0°, etc., which confirms its unique crystal structure. At the same time, TODI also shows obvious diffraction peaks at 10.0°, 15.5°, 18.5°, etc. When turning to the prepared cocrystal product TCNB-TODI, we observed new sharp diffraction peaks at 8.5° and 12.5° in the diffraction spectrum of TCNB-TODI. These newly emerged diffraction peaks are direct evidence of the interaction between the donor and acceptor molecules during the cocrystal formation process to assemble into a new crystalline state. The results demonstrate the successful preparation of the organic cocrystal TCNB-TODI and provide a structural basis for its subsequent applications.

[0041] Fourier transform infrared spectrum of organic cocrystal TCNB-TODI cocrystal (recording range 4000-500 cm -1 ) showed that compared with the donor-acceptor component monomers, the characteristic IR peaks of the organic cocrystals shifted slightly (e.g. Figure 3 shown).

[0042] Specifically, the double bond absorption peak on the benzene ring of TODI is from 2282 cm -1 Move to 2289cm -1 At the same time, the -C≡N stretching vibration peak in TCNB shifts from 2245 cm -1 The peak shifted significantly to 2289 cm-1 in the TCNB-TODI eutectic. -1 The changes in these peak positions indicate that the electron cloud density of the donor and acceptor molecules changes during the cocrystal formation process, and the charge transfer interaction serves as the intrinsic driving force for the formation of the cocrystal. By comparing the IR spectra of the monomer and the cocrystal, it can be determined that the TCNB-TODI organic cocrystal forms a peak at 3118 cm -1 、3051cm -1 and 2289cm -1 The characteristic peaks of TCNB-TODI were observed, proving that the TCNB-TODI organic cocrystal was successfully synthesized by liquid-assisted grinding.

[0043] The morphology of TCNB-TODI cocrystal was characterized by transmission electron microscopy (e.g. Figure 7 TCNB-TODI has a flat rod-like structure with a diameter of 0.26±0.01μm and a length of about 1μm.

[0044] The organic cocrystal was scanned by UV-visible spectrophotometer (e.g. Figure 5 A new absorption peak appeared in the mixture of TODI and TCNB, indicating the formation of a complex.

[0045] Notably, TCNB exhibits almost no absorption peak beyond 400 nm, whereas TODI and the organic cocrystal TCNB-TODI exhibit absorption peaks extending to approximately 800 nm. Compared to the precursor, the cocrystal TCNB-TODI exhibits a red-shifted peak (CT absorption band). This broad absorption peak is red-shifted from 330 nm for TCNB and 315 nm for TODI to approximately 450 nm for TCNB-TODI, indicating the presence of a charge transfer (CT) transition.

[0046] Solid-state fluorescence spectroscopy (eg Figure 6 The fluorescence emission intensity of TCNB and TODI at their maximum excitation wavelengths is relatively weak. However, the fluorescence emission intensity of the TCNB-TODI cocrystal is significantly enhanced compared to the ligand. Its maximum excitation and emission wavelengths are 348.0 nm and 510.8 nm, respectively, with a half-width (FWHM) of approximately 75 nm. This indicates that the TCNB-TODI organic cocrystal exhibits excellent luminescence properties. This result indicates that the combination of TCNB and TODI triggers a fluorescence effect, resulting in the TCNB-TODI cocrystal exhibiting strong yellow fluorescence.

[0047] Example 3: Study on the Thermal Stability of Organic Cocrystal TCNB-TODI

[0048] Thermogravimetric analysis (TG) curves of the organic cocrystal TCNB-TODI were measured under a nitrogen atmosphere over a temperature range of 30-800°C at a heating rate of 10°C / min. The results showed that the thermal stability of the experimentally prepared organic cocrystal TCNB-TODI was intermediate between the two monomeric components. Below 120°C, the TG curve of the organic cocrystal TCNB-TODI exhibited a stable baseline, reflecting the stable crystalline structure of the TCNB-TODI cocrystal. When the temperature was raised to 164°C, a weight loss peak appeared, likely due to the loss of TODI. As the temperature further increased, the driving force for molecular self-assembly within the cocrystal system was disrupted, and TCNB molecules gradually precipitated from the cocrystal system. By the time the temperature reached 800°C, 21.25% of the initial mass of the TCNB-TODI cocrystal remained. The mass of the monomeric TODI had decreased by 99.36%, while the remaining mass of TCNB was 26.72%.

[0049] Example 4: Performance study of the fluorescence sensor based on organic cocrystal TCNB-TODI for the determination of tetracycline (TC)

[0050] Take 10 mg of organic cocrystal TCNB-TODI and dissolve it in 10 mL of aqueous solution to prepare 1 g / L organic cocrystal TCNB-TODI solution; at the same time, prepare 10 -3 mol / L tetracycline solution, set aside.

[0051] To further evaluate the reproducibility of a fluorescent sensor based on the organic cocrystal TCNB-TODI for the determination of tetracycline (TC), a systematic study was conducted on TCNB-TODI organic cocrystals prepared from different batches and stored for the same period of time. The experimental results showed that the peak positions of the PXRD patterns of the organic cocrystals prepared from batches 1, 2, and 3 remained consistent ( Figure 9 A), indicating that the organic co-crystals prepared from different batches have a high degree of structural consistency. A 1g / L organic co-crystal sample was diluted to 500μM for fluorescence excitation. Under the same excitation conditions, the organic co-crystals prepared from different batches all showed stable fluorescence intensity and the same emission wavelength ( Figure 9 B), which shows that the TCNB-TODI organic cocrystal has excellent reproducibility and can achieve mass production of organic cocrystals.

[0052] In order to evaluate the stability of the fluorescent sensor based on TCNB-TODI organic cocrystal in measuring TC, a time stability test was conducted on the cocrystal products prepared in the same batch. The results showed that the PXRD peak position of the cocrystal product remained unchanged after 1 day, 10 days, and 30 days ( Figure 10 A), which indicates that the TCNB-TODI organic cocrystal can maintain its structural stability over a long period of time. At the same time, a 1g / L organic cocrystal sample was diluted to 500μM for fluorescence excitation. Under the same excitation conditions, the fluorescence intensity and emission wavelength of these cocrystal products did not change significantly over time ( Figure 10 B), further confirming that the TCNB-TODI organic cocrystal has good temporal stability and can be stored for a long time.

[0053] Optimization of Fluorescence Detection Conditions for Organic Cocrystals

[0054] Preliminary experiments showed that tetracycline can significantly quench the fluorescence intensity of the organic cocrystal TCNB-TODI, which provides a possibility for designing an efficient fluorescence sensor based on the organic cocrystal TCNB-TODI to measure tetracycline. To optimize the performance of this sensor, we further explored the effects of pH and quenching reaction time on the fluorescence intensity of the organic cocrystal TCNB-TODI. 500 μL of a 1 g / L organic cocrystal sample was added to 10 -3 100 μL of mol / L tetracycline was added to maintain the final solution volume at 1 ml and the pH was adjusted to 1-14. Figure 11 As shown in (A), within the pH range of 1 to 10, the fluorescence response of TCNB-TODI slightly increased with increasing pH; when the pH value increased from 10 to 14, its fluorescence response decreased significantly.

[0055] In addition, 500 μL of 1 g / L organic eutectic sample was added with 10-3 100 μL of mol / L tetracycline was added, and water was added to make the final solution volume 1 ml. The fluorescence intensity of TCNB-TODI at different time points after the addition of TC was measured. We found that the reaction was complete within 16 minutes, and the fluorescence intensity was stable at around 646 nm (such as Figure 11 B), demonstrating excellent stability. These optimization results provide important insights for the practical application of TCNB-TODI-based fluorescence sensors for TC measurement. We continued to use a neutral solution (pH = 7) in subsequent experiments because the pH of most natural environments is 7. While the fluorescence intensity at pH 7 is not the highest, it is still relatively strong, eliminating the need for pH adjustment in subsequent experiments.

[0056] Linearity testing and fitting of organic cocrystals

[0057] Take 500 μL of 1 g / L organic eutectic sample and add 10 -3 After adding 10-160 μM of tetracycline, water was added to maintain the final solution volume at 1 mL. At this time, the tetracycline concentration was between 10-160 μM. As the amount of tetracycline added increased, the fluorescence intensity of the prepared organic cocrystal TCNB-TODI gradually decreased, especially when the tetracycline concentration was within the range of 10-160 μM, and its change showed a good linear relationship (such as Figure 12 (As shown). Within this concentration range, the detection limit of tetracycline is 1.09 μM, a value calculated using the formula LOD = 3σ / s (where σ represents the standard deviation of the blank signal and s is the slope of the calibration curve in the low concentration range). When the tetracycline concentration exceeds 160 μM, the fluorescence intensity of the system stabilizes, indicating that the reaction is complete. Compared with tetracycline fluorescence sensors reported in existing literature, the preparation of this organic cocrystal TCNB-TODI is simpler and requires less time. In addition, the analysis time is shortened by more than 3 hours compared to other reports.

[0058] Selectivity experiments of organic cocrystals

[0059] In order to evaluate the selectivity of the organic cocrystal fluorescence sensor for tetracycline, we took 500 μL of 1 g / L organic cocrystal TCNB-TODI sample and added equal volumes of various 10 -3 mol / L antibiotic analogs (including tetracycline, creatine, erythromycin, neomycin sulfate, glufosinate, thiamphenicol, sulfadiazine, chloramphenicol, florfenicol, sulfamethoxazole, sulfapyridine) to maintain the final solution volume at 1 ml. Figure 13 A. Figure 13As shown in Figure B, with the exception of tetracycline, the ΔF values ​​of the other antibiotics remained almost unchanged, with the I0 / I ratio remaining near 1. However, upon addition of tetracycline, the fluorescence intensity of the sample decreased significantly to one-third of its original value. These results demonstrate that the organic cocrystal TCNB-TODI exhibits excellent selectivity for tetracycline.

[0060] Anti-interference experiment of organic cocrystal

[0061] To further explore whether the presence of other antibiotics would interfere with the detection of tetracycline by organic cocrystal TCNB-TODI, we conducted anti-interference experiments.

[0062] By comparing the fluorescence intensity of the organic cocrystal TCNB-TODI after adding tetracycline alone and adding tetracycline in the presence of other antibiotics (such as Figure 14 We found that the presence of other antibiotics, such as erythromycin, did not affect the quenching effect of tetracycline on the fluorescence intensity of TCNB-TODI (e.g., the organic cocrystal TCNB-TODI + erythromycin + tetracycline). Even in the complex environment of other antibiotics, the addition of tetracycline significantly reduced the fluorescence intensity of the organic cocrystal sample. This result demonstrates that the presence of other antibiotics has minimal impact on the detection of tetracycline by TCNB-TODI. Even in complex environments, the organic cocrystal TCNB-TODI maintains excellent specific recognition and anti-interference capabilities for tetracycline.

[0063] Study on the detection mechanism of organic cocrystals

[0064] Based on the principle that the fluorescence intensity of organic cocrystal TCNB-TODI can be weakened or enhanced through interactions in the presence of target analytes, organic cocrystal TCNB-TODI can detect a variety of analytes. Fluorescence quenching mechanisms generally include dynamic quenching, static quenching, fluorescence energy transfer, inner filter effect (IFE), and self-quenching and self-absorption. Energy transfer mechanisms such as Forster resonance energy transfer (FRET), Dexter energy transfer (DET), and surface energy transfer (SET) also play a role.

[0065] When the aqueous solution of the organic cocrystal TCNB-TODI contains tetracycline, a substance that absorbs fluorescence excitation light, the emitted light is absorbed, resulting in a decrease in fluorescence intensity, which is likely related to the IFE quenching mechanism. To further explore the sensing mechanism, we studied the fluorescence spectrum of the organic cocrystal under 348 nm excitation ( Figure 15 A) UV-visible spectra of different antibiotics ( Figure 15B). In particular, the UV-visible absorption spectrum of tetracycline partially overlaps with the fluorescence spectrum of the organic cocrystal TCNB-TODI. When TC comes into contact with the fluorescent substance TCNB-TODI, TC may absorb the photon energy emitted by TCNB-TODI or receive energy from the fluorescent substance, causing the excited state energy level of the fluorescent substance to shift to a non-excited state energy level, resulting in the disappearance or weakening of the fluorescence signal. This is consistent with the mechanism of action of IFE. In contrast, other antibiotics such as erythromycin do not show similar spectral overlap ( Figure 15 ).

[0066] Application Examples

[0067] In order to investigate the practicality of this detection method, we applied the developed organic cocrystal TCNB-TODI to the detection of tetracycline in an actual sample (Cuihu Lake water sample). 10 mg of the organic cocrystal was dissolved in 10 mL of Cuihu Lake water sample, 500 μL of the actual sample was taken, and 10 -3 After adding 100 μL of 1 mol / L tetracycline, Cuihu water was added to maintain a final solution volume of 1 mL. Fluorescence intensity was measured and the organic cocrystal TCNB-TODI demonstrated excellent performance in detecting TC. As shown in Table 1, the spiked recoveries for TC using TCNB-TODI ranged from 100.77% to 105.61%, with a relative standard deviation of less than 5.49% (n=3). This result demonstrates that the organic cocrystal TCNB-TODI fluorescence detection method has promising practical applications for tetracycline detection.

[0068] Table 1 TCNB-TODI detection of TC (n=3)

[0069]

[0070] Comparison of different fluorescence detection methods for tetracycline

[0071] Existing literature has reported a variety of analytical methods for determining tetracycline. For example, Zhou Tong's team developed a fluorescence sensor based on nitrogen-doped carbon quantum dots. For details, see [1] Zhou Tong, Wu Chen, Zhao Wen, et al. Detection of tetracycline in pork by fluorescence method using nitrogen-doped carbon quantum dots [J]. Journal of Chinese Institute of Food Science and Technology, 2024, 24(02): 303-314. This method has high sensitivity and a detection limit of 89.26 μg / L. Yin Xinyue, Yang Ziyan and others designed fluorescent probes with different ion ratios to analyze the presence of tetracycline. For details, see [2] Yin Xinyue, Deng Xinyi, Xiang Yuhong, et al. Detection of tetracycline in milk based on ratiometric fluorescence sensor of non-conjugated polymer dots and Eu~(3+) [J / OL]. Journal of Capital Normal University (Natural Science Edition), 1-15 [2024-04-08]; [3] Yang Ziyan. Study on a new method for fluorescence detection of thiram and tetracycline based on silver nanoclusters [D]. Huazhong Agricultural University, 2023; their LODs were 11.8 nmol / L and 0.07 μmol / L, respectively, with excellent sensitivity. Thanks to the use of efficient sample pretreatment technology and high-sensitivity instruments, these methods have good sensitivity, but they often consume more time and manpower.

[0072] The organic cocrystal TCNB-TODI fluorescence sensor of this invention stands out for its simple and rapid performance in measuring pollutants. Compared to other reported tetracycline fluorescence detection methods, this sensor not only boasts slightly higher sensitivity but also boasts simpler and faster synthesis and operation. Importantly, the interaction between TCNB-TODI and tetracycline is extremely rapid, with measurements completed in just 16 minutes, significantly saving time for target analyte analysis (as shown in Table 2).

[0073] Table 2 Comparison of different fluorescence detection methods for tetracycline

[0074]

[0075] In summary, the present invention successfully prepared a high-quantum-yield fluorescent organic cocrystal TCNB-TODI using a liquid grinding method, and explored its application as an efficient fluorescence sensor for the detection of tetracycline (TC) antibiotic residues. When the organic cocrystal came into contact with tetracycline, it exhibited significant fluorescence quenching, which provided us with a rapid and sensitive TC detection method. The fluorescence detection method exhibited a good linear response in the concentration range of 10 to 160 μM, indicating that it has excellent performance in the quantitative detection of TC. In addition, the detection method also exhibited strong anti-interference and excellent selectivity for tetracycline, giving it significant advantages in practical applications. Compared with traditional tetracycline detection methods, the fluorescence detection method proposed in this study is more convenient and rapid, and has extremely high practical value.

[0076] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. Organic eutectic TCNB-TODI, characterized by: The organic cocrystal is prepared by liquid-assisted grinding with 1,2,4,5-tetracyanobenzene as the acceptor molecule and dimethylbiphenyl diisocyanate as the donor molecule. Here are the steps: S1: Take appropriate amounts of 1,2,4,5-tetracyanobenzene and dimethylbiphenyl diisocyanate in a mortar, add acetonitrile solution dropwise, and grind for 10 min until the mixture turns into a yellow powder; S2. Place the yellow powder obtained by grinding in an oven at 75°C and dry for 24 hours.

2. The method for preparing the organic cocrystal TCNB-TODI according to claim 1, wherein: The steps include: S1: Take appropriate amounts of 1,2,4,5-tetracyanobenzene and dimethylbiphenyl diisocyanate in a mortar, add acetonitrile solution dropwise, and grind for 10 min until the mixture turns into a yellow powder; S2. Place the yellow powder obtained by grinding in an oven at 75°C and dry for 24 hours.

3. The method for preparing the organic cocrystal TCNB-TODI according to claim 2, wherein: In the step S1, the molar ratio of 1,2,4,5-tetracyanobenzene to dimethylbiphenyl diisocyanate is 1:

1.

4. The use of the organic cocrystal TCNB-TODI according to claim 1, characterized in that: Used to prepare fluorescent sensors based on organic cocrystal TCNB-TODI.

5. The use of the organic cocrystal TCNB-TODI according to claim 4, characterized in that: The organic cocrystal TCNB-TODI-based fluorescent sensor can be used to detect tetracycline.

6. The use of the organic cocrystal TCNB-TODI according to claim 5, characterized in that: During the detection, a 1 g / L organic cocrystal TCNB-TODI solution was placed in the test solution, reacted for 16 minutes, and its fluorescence intensity was measured. Based on the linear relationship between the fluorescence intensity of the organic cocrystal TCNB-TODI and the tetracycline concentration, the tetracycline concentration could be obtained.

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