High-sensitivity ethylene fluorescent probe based on carbon dots as well as preparation method and application of high-sensitivity ethylene fluorescent probe
By preparing carbon dot-based ethylene fluorescent probes, and using olefin metathesis reaction to change the carbon dot electronic structure, the problem that existing carbon dot materials cannot respond to non-polar ethylene is solved, high sensitivity and high selectivity ethylene detection and imaging are achieved, and the application range of carbon dot materials is expanded.
Patent Information
- Application Number
- CN202510425756.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-07
- Publication Date
- 2025-07-18
AI Technical Summary
Existing carbon dot fluorescent probes cannot effectively respond to non-polar gas ethylene, resulting in low detection sensitivity, poor selectivity and long response time, making it difficult to achieve real-time detection and spatial resolution imaging of ethylene in complex biological substrates.
Pre-reacting the Grubbs catalyst with a compound with an alkenyl group at the end gives a precursor, and then reacting with aromatic amine compounds and carboxylic acid compounds under heating conditions, a carbon dot fluorescent probe that can specifically recognize ethylene was prepared, and the electronic structure of the carbon dot was changed by olefin metathesis reaction, resulting in an increase in fluorescence intensity.
The high sensitivity detection limit for ethylene is as low as 0.12 ppm, which can quickly respond and eliminate interference from other substances, and realize spatially resolved fluorescence imaging of ethylene in plant tissues. It is suitable for agricultural production, food preservation and plant physiology research.
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Figure CN120329943A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical fields of nanomaterials and gas sensing technology, and particularly relates to a highly sensitive ethylene fluorescence probe based on carbon dots, its preparation method and application, and more particularly to a carbon dot fluorescence probe for real-time detection and imaging of ethylene in plant tissues, its preparation method and application. Background Art
[0002] Ethylene is an important plant hormone that is widely involved in physiological processes such as plant growth, fruit ripening, and stress responses. However, ethylene is a low-reactivity non-polar gas molecule, and existing detection methods usually rely on its coordination reactions with metal ions (such as Cu(I), Ag(I), Ru(III), etc.), which have problems such as low sensitivity, poor selectivity, and long response time. Moreover, it is difficult for existing methods to achieve real-time detection and spatial resolution imaging of ethylene in complex biological matrices (such as plant tissues). Therefore, developing a highly sensitive and selective ethylene detection method that can achieve real-time detection and spatial resolution imaging is of great scientific significance and application value for in-depth study of the role of ethylene in plant growth, fruit ripening, and stress responses, as well as for optimizing agricultural production and food preservation technologies.
[0003] In recent years, carbon dots (CDs), as a new type of fluorescent nanomaterial, have shown great potential in the field of gas sensing due to their excellent biocompatibility, fluorescent properties, and large specific surface area. Existing carbon dot fluorescence probes are only applicable to the detection of polar gases (such as NO, H2S) or highly reactive molecules (such as reactive oxygen species), and their mechanism relies on the direct interaction between the gas and polar functional groups (such as -COOH, -NH2) on the surface of the carbon dots. However, ethylene, as a non-polar gas molecule, lacks effective interaction sites with carbon dots.
[0004] Therefore, the present invention constructs a carbon dot fluorescence probe that can specifically recognize non-polar ethylene, solves the inherent technical limitation in the prior art that carbon dot materials cannot effectively respond to non-polar gases, proves that carbon dots are also applicable to the detection of non-polar gases, and fills the technical gap in this field. Summary of the Invention
[0005] Aiming at the above deficiencies of the prior art, the present invention provides an ethylene fluorescence probe based on carbon dots with high sensitivity and capable of achieving quantitative detection and fluorescence imaging of ethylene in plant tissues, its preparation method and application, solves the problems of low sensitivity, poor selectivity, and long response time of existing ethylene detection methods, and at the same time fills the gap of carbon dots in the field of ethylene detection.
[0006] To achieve the above object, the specific technical solutions of the present invention are as follows:
[0007] In a first aspect, the present invention provides a highly sensitive ethylene fluorescent probe based on carbon dots. A precursor is obtained by pre-reacting a Grubbs catalyst with a compound having an alkenyl group at the end, and then the precursor is reacted with an aromatic amine compound and a carboxylic acid compound under heating conditions to obtain the fluorescent probe; the fluorescent probe exhibits a significant fluorescence enhancement effect in the presence of ethylene.
[0008] Aiming at the problem that carbon dot fluorescent probes in the prior art cannot effectively respond to non-polar gases, the present invention pre-reacts a compound having an alkenyl group at the end with a Grubbs catalyst to obtain a precursor. The precursor can undergo a specific reaction with ethylene through olefin metathesis reaction, thereby changing the electronic structure of the carbon dots and resulting in a change in fluorescence intensity. The carbon dot fluorescent probe of the present invention has weak fluorescence in the absence of ethylene, but after a specific reaction with ethylene molecules, the fluorescence intensity is significantly enhanced; at the same time, the carbon dot fluorescent probe has a specific response to ethylene and can exclude the interference of other substances (such as common metal ions, anions, biological thiols, and unsaturated metabolic molecules in plants, etc.); in addition, the carbon dot fluorescent probe can also achieve spatial resolution fluorescence imaging of ethylene in plant tissues and has broad application prospects in the fields of agricultural production, food preservation, and plant physiology research.
[0009] Further, the compound having an alkenyl group at the end includes, but is not limited to, R-CH=CH2 or R1R2C=CH2, where: R is selected from C1-C8 alkyl, aryl, heteroaryl, or substituted aryl; R1 and R2 are each independently selected from hydrogen, C1-C6 alkyl, aryl, or heteroaryl, and are not both hydrogen at the same time.
[0010] Still further, the compound having an alkenyl group at the end includes, but is not limited to, styrene (R = phenyl), 1-hexene (R = n-butyl), 1,1-diphenylethylene (R1 = R2 = phenyl), or N-vinylcarbazole (R = carbazolyl).
[0011] Further, the aromatic amine compound is an aromatic diamine compound and / or an aromatic aminophenol compound, and the aromatic amine compound includes, but is not limited to, at least one of o-phenylenediamine, p-phenylenediamine, o-aminophenol, and p-aminophenol.
[0012] Further, the carboxylic acid compound includes, but is not limited to, at least one of maleic acid, terephthalic acid, trimellitic acid, 2,6-dipyridinedicarboxylic acid, 3,4-diaminobenzoic acid, nicotinic acid, 1,2,3-propanetricarboxylic acid, and 1,2,4-benzenetricarboxylic acid.
[0013] Further, the molar ratio of the Grubbs catalyst to the compound having an alkenyl group at the end is 1:(10~40).
[0014] Further, the mass ratio of the precursor, the aromatic amine compound and the carboxylic acid compound is (3 - 12):(10 - 35):35.
[0015] Still further, the mass ratio of the precursor, the aromatic amine compound and the carboxylic acid compound is 6:32:35.
[0016] In a second aspect, the method for preparing the highly sensitive ethylene fluorescence probe based on carbon dots according to the present invention comprises the following steps:
[0017] Mix a compound with an alkenyl end and a Grubbs catalyst in an organic solvent for a pre - reaction; after the reaction is completed, remove the solvent, wash and dry to obtain a precursor;
[0018] Uniformly disperse the precursor, the aromatic amine compound and the carboxylic acid compound in an organic solvent, and react the dispersed mixture under heating conditions; after the reaction is completed, purify and dry to obtain the highly sensitive ethylene fluorescence probe based on carbon dots.
[0019] Further, the organic solvent includes but is not limited to methanol, ethanol, dichloromethane, N,N - dimethylformamide.
[0020] Further, the temperature of the pre - reaction is 10 - 50 °C and the time is 1 - 6 h.
[0021] Further, the temperature of the reaction under heating conditions is 100 - 200 °C and the time is 6 - 16 h.
[0022] Further, the purification is to perform dialysis treatment on the obtained suspension in pure water using a cellulose membrane with a molecular retention rate of 500 - 3000 Da (Dalton) to remove the solvent and unreacted raw materials.
[0023] In a third aspect, the present invention provides the application of the fluorescence probe in detecting ethylene or preparing an ethylene detection product.
[0024] Compared with the prior art, the advantages of the present invention are as follows:
[0025] 1. Filling a technical gap: At present, carbon dot materials for ethylene detection have not been reported. The present invention is the first highly sensitive carbon dot fluorescence probe for ethylene detection, filling the technical gap in this field.
[0026] 2. Breakthrough in the application field: The detection object of carbon dot materials is extended to non - polar gas small molecules.
[0027] 3. High sensitivity: The ethylene detection fluorescence probe provided by the present invention has a detection limit for ethylene as low as 0.12 ppm, which is significantly better than the existing ethylene detection methods (usually about 1 ppm).
[0028] 4. High selectivity: The ethylene detection fluorescent probe provided by the present invention has a specific response to ethylene and can exclude the interference of other substances (such as common metal ions, anions, biological thiols, and unsaturated metabolic molecules in plants, etc.).
[0029] 5. Fast response: The ethylene detection fluorescent probe provided by the present invention can complete the detection of ethylene within 3 minutes and is suitable for real-time dynamic monitoring.
[0030] 6. Versatility: The ethylene detection fluorescent probe provided by the present invention can not only achieve highly sensitive detection of ethylene but also realize spatially resolved fluorescence imaging of ethylene in plant tissues.
[0031] 7. Simple preparation method: The preparation method of the ethylene detection fluorescent probe provided by the present invention is easy to operate and suitable for large-scale production.
[0032] 8. Wide application prospects: The ethylene detection fluorescent probe provided by the present invention has wide application prospects in the fields of agricultural production, food preservation, and plant physiology research, providing a new tool for ethylene-related research. Brief Description of the Drawings
[0033] Figure 1 It is a schematic diagram of the method for preparing e-CDs in Example 1 of the present invention;
[0034] Figure 2 It is the characterization results of the e-CDs prepared in Example 1 of the present invention; among them, (a) is the transmission electron microscope image of e-CDs; (b) is the particle size distribution histogram of e-CDs; (c) is the X-ray diffraction pattern of e-CDs; (d) is the Fourier transform infrared spectrum of e-CDs;
[0035] Figure 3 It is the fluorescence spectra of e-CDs before and after reacting with ethylene;
[0036] Figure 4 It is the fluorescence spectra of e-CDs after reacting with different concentrations of ethylene;
[0037] Figure 5 It is the linear relationship between the fluorescence intensity at 576 nm and the ethylene concentration;
[0038] Figure 6 It is the selectivity test results of e-CDs (the test objects are common ions, biological thiols, and ethylene);
[0039] Figure 7 It is the selectivity test results of e-CDs (the test objects are common unsaturated metabolic molecules in plants and ethylene);
[0040] Figure 8Detection of the change in ethylene concentration released by e-CDs from different fruits at different incubation times (2 - 12 h);
[0041] Figure 9 Detection of the ethylene release rate of e-CDs from different fruits;
[0042] Figure 10 Fluorescence imaging of ethylene released from mangoes treated with ACC, H2O, and PZA by e-CDs;
[0043] Figure 11 Fluorescence spectra of j-CDs before and after reaction with ethylene;
[0044] Figure 12 Fluorescence spectra of b-CDs before and after reaction with ethylene;
[0045] Figure 13 Fluorescence spectra of n-CDs before and after reaction with ethylene. Detailed implementation mode
[0046] The technical solutions of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.
[0047] The present invention provides a highly sensitive ethylene fluorescence probe based on carbon dots. The probe is obtained by pre-reacting a Grubbs catalyst with a compound having an alkenyl group at the end to obtain a precursor, and then reacting the precursor with an aromatic amine compound and a carboxylic acid compound under heating conditions. The fluorescence probe exhibits a significant fluorescence enhancement effect in the presence of ethylene.
[0048] In some examples, the compound having an alkenyl group at the end includes, but is not limited to, R-CH=CH2 or R1R2C=CH2, where: R is selected from C1-C8 alkyl, aryl, heteroaryl or substituted aryl; R1 and R2 are each independently selected from hydrogen, C1-C6 alkyl, aryl or heteroaryl, and are not both hydrogen at the same time. Specifically, the compound having an alkenyl group at the end includes, but is not limited to, styrene (R = phenyl), 1-hexene (R = n-butyl), 1,1-diphenylethylene (R1 = R2 = phenyl) or N-vinylcarbazole (R = carbazolyl).
[0049] In some examples, the aromatic amine compound is an aromatic diamine compound and / or an aromatic aminophenol compound, and the aromatic amine compound includes but is not limited to at least one of o-phenylenediamine, p-phenylenediamine, o-aminophenol, and p-aminophenol. The carboxylic acid compound includes but is not limited to at least one of maleic acid, terephthalic acid, trimellitic acid, 2,6-dipyridinedicarboxylic acid, 3,4-diaminobenzoic acid, nicotinic acid, 1,2,3-propanetricarboxylic acid, and 1,2,4-benzenetricarboxylic acid.
[0050] In some examples, the molar ratio of the Grubbs catalyst to the compound with an alkenyl end is 1:(10 - 40). The mass ratio of the precursor, the aromatic amine compound, and the carboxylic acid compound is (3 - 12):(10 - 35):35.
[0051] A preparation method of a highly sensitive ethylene fluorescence probe based on carbon dots includes the following steps:
[0052] Mix the compound with an alkenyl end and the Grubbs catalyst in an organic solvent, and pre-react at 10 - 50 °C for 1 - 6 h; after the reaction is completed, remove the solvent, wash and dry to obtain the precursor;
[0053] Uniformly disperse the precursor, the aromatic amine compound, and the carboxylic acid compound in an organic solvent, and react the dispersed mixture at 100 - 200 °C for 6 - 16 h; after the reaction is completed, use a cellulose membrane with a molecular cut-off rate of 500 - 3000 Da (Dalton) to dialyze the obtained suspension in pure water to remove the solvent and unreacted raw materials, and dry to obtain a highly sensitive ethylene fluorescence probe based on carbon dots.
[0054] Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood as having the meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. In case of contradiction, this specification shall prevail.
[0055] In the following specific examples, all kinds of raw materials, reagents, instruments, and equipment used can be obtained through market purchase or can be obtained by existing methods.
[0056] Example 1
[0057] A highly sensitive ethylene fluorescence probe based on carbon dots (for the schematic diagram of the preparation method, see Figure 1 )
[0058] 1. Synthesis of Precursor 1
[0059] Styrene (R = phenyl) (83 μL, 0.72 mmol) and Grubbs catalyst (59 mg, 0.072 mmol) were added to 5 mL of dichloromethane and reacted at room temperature for 2 h. After the reaction, the solvent was removed under vacuum, washed repeatedly with acetone (3 mL), and dried under vacuum for several hours to obtain a dark green solid precursor 1. Precursor 1 can be used to prepare carbon dot fluorescent probes without purification such as column chromatography.
[0060] 2. Synthesis of Carbon Dot Fluorescent Probes
[0061] Precursor 1 (6 mg), o-phenylenediamine (32 mg), and maleic acid (35 mg) were dissolved in 10 mL of absolute ethanol and sonicated for 10 minutes to assist dissolution. After uniform dispersion, the dispersed mixture was transferred to a 25 mL Teflon-lined autoclave and reacted at 120 °C for 12 h. After natural cooling to room temperature, the obtained suspension was dialyzed in pure water for 12 h using a cellulose membrane with a molecular cut-off rate of 500 Da (Dalton) to remove ethanol and unreacted raw materials. Finally, the solution was collected and freeze-dried in a vacuum freeze dryer for 48 h to obtain a dark green solid carbon dot fluorescent probe (the carbon dot fluorescent probe prepared in this example was denoted as e-CDs).
[0062] 3. Characterization of e-CDs
[0063] The present invention characterized e-CDs, and the results are shown in Figure 2 . Figure 2 The transmission electron microscope (TEM) image in (a) shows that e-CDs are spherical in distribution. Figure 2 The particle size distribution histogram in (b) shows that the diameter of e-CDs is distributed between 3 - 12 nm, and the average diameter is 6.95 ± 0.13 nm. Figure 2 The X-ray diffraction (XRD) pattern in (c) indicates that e-CDs have a certain degree of amorphous structure. Figure 2 The Fourier transform infrared spectroscopy (FT-IR) in (d) shows that the surface of e-CDs contains groups such as hydroxyl (O-H), carbon-carbon double bond (C=C), carbonyl (C=O), and carbon-hydrogen bond (C-H).
[0064] 4. Spectral Properties of e-CDs
[0065] The present invention measured the fluorescence spectra, ultraviolet-visible absorption spectra, and fluorescence quantum yields of e-CDs before and after reaction with ethylene in pure aqueous solution, and the fluorescence quantum yield was measured by the absolute quantum fluorescence yield method. The measurement results are shown in Table 1.
[0066] Table 1: Spectral Properties of e-CDs before and after Reaction with Ethylene
[0067]
[0068] In addition, the fluorescence spectra of e-CDs before and after the reaction with ethylene are shown as Figure 3 follows; the fluorescence spectra of e-CDs after the reaction with ethylene at different concentrations (0 - 70 ppm) are shown as Figure 4 follows; the linear relationship between the fluorescence intensity at 576 nm and the ethylene concentration (0 - 70 ppm) is shown as Figure 5 follows. The above experimental results indicate that the fluorescence of the carbon dot fluorescence probe of the present invention is very weak by itself, and the fluorescence intensity increases significantly after the reaction with ethylene.
[0069] 5. Selectivity of e-CDs to ethylene
[0070] The present invention respectively investigated the responses of e-CDs to ethylene, metal ions (K + , Na + , Cu 2+ , Zn 2+ , Ca 2+ , Mg 2+ , Fe 3+ ), anions (F - , Br - , I - , Ac - , CO3 2- , HCO3 - , HSO3 - , S2O3 2- , S2O5 2- , SCN - , SO3 2- , SO4 2- , NO3 - ), biothiols (Hcy, GSH) and other competitive unsaturated plant metabolite molecules (including farnesol, limonene, pinene, terpinene, citronellol and myrcene). The results are shown as Figure 6 and Figure 7 follows. Among them, the concentration of ethylene is 2 ppm, the concentration of various types of terpene compounds is 6 mM, and other substances are 1 mM; it can be seen from the figure that the fluorescence enhancement degree of e-CDs after the reaction with ethylene (2 ppm) is much greater than that of other substances. This result indicates that the carbon dot fluorescence probe of the present invention has good selectivity to ethylene.
[0071] 6. e-CDs are used to monitor the ethylene release rate of different fruits
[0072] The present invention uses e-CDs to monitor the ethylene released during the ripening process of different fruits (apples, mangoes, avocados, passion fruits). The results are shown as Figure 8As shown in the figure, it can be seen that as the fruit sealing time increases, the detected ethylene concentration also gradually rises. Further calculating the ethylene release rate shows that the ethylene release rate of passion fruit is the highest, followed by avocado and mango, and the ethylene release rate of apple is the lowest (as Figure 9 shown). These differences not only reflect the physiological characteristics of various fruits but also indicate their different requirements in post-harvest handling and storage.
[0073] 7. Dynamic Monitoring of Ethylene under Exogenous Stimulation by e-CDs
[0074] In the present invention, e-CDs are used to perform fluorescence imaging on mango slices treated with water (control group), ACC (ethylene synthesis precursor), and PZA (ethylene synthesis inhibitor) respectively to monitor the change in fluorescence intensity of ethylene release in real time. The results are as Figure 10 shown. The figure shows that for the samples treated with ACC, the fluorescence intensity increases significantly with time, indicating that ethylene synthesis is promoted; for the samples treated with PZA, the fluorescence intensity remains at a low level, indicating that ethylene synthesis is inhibited; for the samples treated with water, the fluorescence intensity increases slightly with time, but the increase amplitude is lower than that of the samples treated with ACC. The above results show that the carbon dot fluorescence probe of the present invention can dynamically monitor the synthesis and release of ethylene under exogenous stimulation, and at the same time, through the observation of the control group, its stability and reliability in complex biological matrices are verified.
[0075] Comparative Example 1
[0076] Weigh Grubbs catalyst (or weigh Grubbs catalyst and other raw materials; or weigh Precursor 1 and other raw materials) and dissolve it in 10 mL of absolute ethanol, and use ultrasonic waves to assist in dissolving the mixture for 10 minutes. After uniform dispersion, transfer the dispersed mixture to a 25 mL Teflon-lined autoclave and react at 120 °C for 12 h. After natural cooling to room temperature, use a cellulose membrane with a molecular retention rate of 500 Da (Dalton) to perform dialysis treatment on the obtained suspension in pure water for 12 h to remove unreacted ethanol and raw materials. Finally, collect the solution and freeze-dry it in a vacuum freeze-dryer for 48 h to obtain a solid carbon dot product.
[0077] Prepare a solution with a certain concentration of the obtained carbon dots, introduce ethylene, and the fluorescence change data are shown in Table 2.
[0078] Table 2: Fluorescent Characteristics of Ethylene Response of Carbon Dots Derived from Grubbs Catalyst
[0079]
[0080] Example 2
[0081] A Highly Sensitive Ethylene Fluorescent Probe Based on Carbon Dots
[0082] 1. Synthesis of Precursor 2
[0083] 1-Hexene (R = n-butyl) (760 μL, 6 mmol) and Grubbs catalyst (0.1234 g, 0.15 mmol) were added to 5 mL of dichloromethane and reacted at room temperature for 2 h. After the reaction, the solvent was removed under vacuum, and the residue was washed repeatedly with acetone (3 mL) and dried under vacuum for several hours to obtain a dark brown solid precursor 2. Precursor 2 can be used for the preparation of carbon dots without purification such as column chromatography.
[0084] 2. Synthesis of Carbon Dot Fluorescent Probe
[0085] Precursor 2 (6 mg), o-phenylenediamine (32 mg) and maleic acid (35 mg) were dissolved in 10 mL of absolute ethanol, and the mixture was sonicated for 10 minutes to assist dissolution. After uniform dispersion, the dispersed mixture was transferred to a 25 mL Teflon-lined autoclave and reacted at 120 °C for 12 h. After natural cooling to room temperature, the obtained suspension was dialyzed against pure water for 12 h using a cellulose membrane with a molecular cut-off of 500 Da (Dalton) to remove ethanol and unreacted raw materials. Finally, the solution was collected and freeze-dried in a vacuum freeze-dryer for 48 h to obtain a black solid carbon dot fluorescent probe (the carbon dot fluorescent probe prepared in this example was denoted as j-CDs).
[0086] 3. Spectral Properties of j-CDs:
[0087] The fluorescence spectra of j-CDs before and after reaction with ethylene were measured in pure aqueous solution, and the test results are shown in Figure 11 .
[0088] Example 3
[0089] Precursor 2, an aromatic amine compound and a carboxylic acid compound were weighed and dissolved in 10 mL of an organic solvent according to a mass ratio of 6:32:35, and the mixture was sonicated for 10 minutes to assist dissolution. After uniform dispersion, the dispersed mixture was transferred to a 25 mL Teflon-lined autoclave and reacted at 120 °C for 12 h. After natural cooling to room temperature, the obtained suspension was dialyzed against pure water for 12 h using a cellulose membrane with a molecular cut-off of 1000 Da (Dalton) to remove the organic solvent and unreacted raw materials. Finally, the solution was collected and freeze-dried in a vacuum freeze-dryer for 48 h to obtain a solid carbon dot product.
[0090] The obtained carbon dots were formulated into a solution of a certain concentration, and ethylene was introduced. The fluorescence change data are shown in Table 3.
[0091] Table 3: Fluorescent Characteristics of Ethylene Response of Carbon Dots Derived from Grubbs Catalyst
[0092]
[0093] Example 4
[0094] A highly sensitive ethylene fluorescence probe based on carbon dots
[0095] 1. Synthesis of precursor 3
[0096] 1,1 - diphenylethylene (R1 = R2 = phenyl) (0.1803 g, 1 mmol) and Grubbs catalyst (0.0824 g, 0.1 mmol) were added to 5 mL of dichloromethane and reacted at room temperature for 2 h. After the reaction, the solvent was removed under vacuum, washed repeatedly with acetone (3 mL), and dried under vacuum for several hours to obtain the black liquid precursor 3. Precursor 3 can be used to prepare carbon dots without purification such as column chromatography.
[0097] 2. Synthesis of the carbon dot fluorescence probe
[0098] Precursor 3 (6 mg), o - phenylenediamine (32 mg), and maleic acid (35 mg) were dissolved in 10 mL of absolute ethanol, and the mixture was dissolved by ultrasonic assistance for 10 minutes. After uniform dispersion, the dispersed mixture was transferred to a 25 mL Teflon - lined autoclave and reacted at 120 °C for 12 h. After natural cooling to room temperature, the obtained suspension was dialyzed in pure water for 12 h using a cellulose membrane with a molecular cut - off rate of 500 Da (Dalton) to remove ethanol and unreacted raw materials. Finally, the solution was collected and freeze - dried in a vacuum freeze - dryer for 48 h to obtain a black solid carbon dot fluorescence probe (the carbon dot fluorescence probe prepared in this example is denoted as b - CDs).
[0099] 3. Spectral properties of b - CDs
[0100] The fluorescence spectra of b - CDs before and after reaction with ethylene were measured in pure aqueous solution, and the test results are shown in Figure 12 .
[0101] Example 5
[0102] A highly sensitive ethylene fluorescence probe based on carbon dots
[0103] 1. Synthesis of precursor 4
[0104] N-vinylcarbazole (R = carbazolyl) (0.1932 g, 1 mmol) and Grubbs catalyst (0.0824 g, 0.1 mmol) were added to 5 mL of dichloromethane and reacted at room temperature for 2 h. After the reaction, the solvent was removed under vacuum, washed repeatedly with acetone (3 mL), and dried under vacuum for several hours to obtain a dark purple solid precursor 4. The precursor 4 can be used to prepare carbon dots without purification methods such as column chromatography.
[0105] 2. Synthesis of Carbon Dots Fluorescent Probe
[0106] Precursor 4 (6 mg), o-phenylenediamine (32 mg), and maleic acid (35 mg) were dissolved in 10 mL of absolute ethanol, and the mixture was dissolved by ultrasonic assistance for 10 minutes. After uniform dispersion, the dispersed mixture was transferred to a 25 mL Teflon-lined autoclave and reacted at 120 °C for 12 h. After natural cooling to room temperature, the obtained suspension was dialyzed in pure water for 12 h using a cellulose membrane with a molecular cut-off rate of 500 Da (Dalton) to remove ethanol and unreacted raw materials. Finally, the solution was collected and freeze-dried in a vacuum freeze-dryer for 48 h to obtain a dark purple solid carbon dots fluorescent probe (the carbon dots fluorescent probe prepared in this example was denoted as n-CDs).
[0107] 3. Spectral Properties of n-CDs
[0108] The fluorescence spectra of n-CDs before and after reaction with ethylene were measured in pure aqueous solution, and the test results are shown in Figure 13 .
[0109] In summary, in the present invention, a precursor is obtained by pre-reacting a Grubbs catalyst with a compound having an alkenyl group at the end, and then the precursor is reacted with an aromatic amine compound and a carboxylic acid compound under heating conditions to obtain a carbon dots fluorescent probe. The carbon dots fluorescent probe has good specific recognition and fluorescence enhancement response to non-polar ethylene molecules, can rapidly and highly selectively detect ethylene in complex biological matrices within 3 minutes, and its detection limit is as low as 0.12 ppm. In addition, the carbon dots fluorescent probe can also achieve spatially resolved fluorescence imaging of ethylene in plant tissues, and has broad application prospects in the fields of agricultural production, food preservation, and plant physiology research.
[0110] The above specific embodiments have described the implementation of the present invention in detail. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solutions of the present invention, and these simple variations all belong to the protection scope of the present invention.
Claims
1. A highly sensitive ethylene fluorescence probe based on carbon dots, characterized in that, The precursor is obtained by pre-reacting a Grubbs catalyst with a compound having an alkenyl group at the end, and then the precursor is reacted with an aromatic amine compound and a carboxylic acid compound under heating conditions to obtain the fluorescent probe.
2. The highly sensitive ethylene fluorescence probe based on carbon dots according to claim 1, characterized in that, The compound having an alkenyl group at the end includes, but is not limited to, R-CH=CH2 or R1R2C=CH2, where: R is selected from C1-C8 alkyl, aryl, heteroaryl or substituted aryl; R1 and R2 are each independently selected from hydrogen, C1-C6 alkyl, aryl or heteroaryl, and are not both hydrogen at the same time.
3. The highly sensitive ethylene fluorescence probe based on carbon dots according to claim 2, characterized in that, The compound having an alkenyl group at the end includes, but is not limited to, styrene, 1-hexene, 1,1-diphenylethylene or N-vinylcarbazole.
4. A highly sensitive ethylene fluorescence probe based on carbon dots according to claim 1, characterized in that, The aromatic amine compound includes, but is not limited to, at least one of o-phenylenediamine, p-phenylenediamine, o-aminophenol, p-aminophenol.
5. A highly sensitive ethylene fluorescence probe based on carbon dots according to claim 1, characterized in that, The carboxylic acid compound includes, but is not limited to, at least one of maleic acid, terephthalic acid, trimellitic acid, 2,6-dipyridinedicarboxylic acid, 3,4-diaminobenzoic acid, nicotinic acid, 1,2,3-propanetricarboxylic acid, 1,2,4-benzenetricarboxylic acid.
6. A highly sensitive ethylene fluorescence probe based on carbon dots according to claim 1, characterized in that, The molar ratio of the Grubbs catalyst to the compound having an alkenyl group at the end is 1:(10-40).
7. A highly sensitive ethylene fluorescence probe based on carbon dots according to claim 1, characterized in that, The mass ratio of the precursor, the aromatic amine compound and the carboxylic acid compound is (3-12):(10-35):
35.
8. A highly sensitive ethylene fluorescence probe based on carbon dots according to claim 1, characterized in that, The temperature of the reaction under heating conditions is 110-130 °C, and the time is 8-16 h.
9. The method for preparing a highly sensitive ethylene fluorescent probe based on carbon dots according to any one of claims 1-8, comprising the following steps: Mix the compound having an alkenyl group at the end and the Grubbs catalyst in an organic solvent for pre-reaction; after the reaction is completed, remove the solvent, wash and dry to obtain the precursor; Uniformly disperse the precursor, the aromatic amine compound and the carboxylic acid compound in an organic solvent, and react the dispersed mixture under heating conditions; after the reaction is completed, purify and dry to obtain a highly sensitive ethylene fluorescent probe based on carbon dots.
10. The application of the fluorescent probe according to any one of claims 1-8 in detecting ethylene or preparing an ethylene detection product.