Preparation method and application of amide-silanized fluorescent nano-cluster

Abstract

The invention discloses a preparation method and application of amide-silanized fluorescent nano-clusters (SiANs), and belongs to the crossing field of nano functional materials and agricultural technologies. The silicon-based nano-cluster with the fluorescence characteristic is assembled through double-interface engineering of ammonium carboxylate and an amino functional group silane derivative, and the material is synthesized by adopting a hydrothermal method. The method has the advantages of mild reaction conditions, simplified process steps and low energy consumption, the average particle size of the prepared nano-cluster material is 2.29 nm, and the nano-cluster material has near ultraviolet region fluorescence emission characteristics, good carbon dioxide adsorbability and good biocompatibility. Compared with a blank group, the plant height and the root length of wheat seedlings in a 5mg / L SiANs treatment group are increased by 20% and 80% respectively, and the dry weight and the fresh weight of the plants are increased by 25% and 15% respectively.

Description

Technical Field

[0001] The present invention relates to the intersection of nano-functional material design and agricultural technology, and more specifically to a preparation method of amide-silanized fluorescent nanoclusters (SiANs) based on double-interface molecular assembly and its application in crop photosynthetic regulation. Through the interface engineering of silane network and amide group, light energy conversion and CO 2 The dual functions of adsorption are integrated, thus breaking through the traditional fertilization mode to improve the photosynthetic performance of crops. Background Art

[0002] The global population has exceeded 8 billion, but due to the uneven distribution of arable land resources and limited production efficiency, nearly 1.3 billion people still face food security issues. In order to meet the demand for increased production under limited arable land conditions, the intensive use of fertilizers and pesticides has increased food production, but has led to serious ecological and environmental costs: about 55% of the world's fertilizers enter the water system through leaching, causing eutrophication and causing 12% of anthropogenic greenhouse gas emissions; 98% of pesticides spread to non-target areas, causing a 30%-70% decrease in soil microbial diversity. The extensive chemical application model, while increasing crop yields and stress resistance, triggers a cascade effect of air-water-soil pollution, which has become the core contradiction restricting the green transformation of agriculture.

[0003] Compared with the traditional strategy of exogenous nutrient supplementation, the new agronomic technology based on photosynthetic physiological regulation provides a new solution to break through the biological limitations of light energy utilization efficiency. As the core metabolic process of crop material accumulation, photosynthesis contributes more than 90% of the total dry matter of crops. Limited by the high selectivity of the light response range of the chloroplast photosynthetic pigment system (400-500nm blue-violet light region and 610-660nm red-orange light region), the light energy conversion efficiency of existing crops is generally lower than 30% of the theoretical maximum value. In recent years, the innovative application research of fluorescent nanomaterials in the field of agriculture has continued to deepen.

[0004] However, these technologies mostly focus on the single-dimensional optimization of the light energy capture stage, ignoring the systematic coupling mechanism of the light reaction (electron transport chain) and the dark reaction (Calvin cycle) in photosynthesis. For example, although quantum dot light conversion materials can extend the light absorption spectrum to the entire visible light range (400-700nm), they lack CO 2 The enrichment function leads to an imbalance between the ATP / NADPH synthesis rate and the Rubisco carboxylation demand, resulting in a metabolic mismatch between light energy conversion and carbon assimilation. When the PSII electron transfer rate exceeds the Rubisco carboxylation capacity by 30%, it will trigger an explosive accumulation of reactive oxygen species (ROS), ultimately leading to a photoinhibitory effect. The application of fluorescent nanoclusters with both photoconversion and carbon dioxide adsorption capabilities to regulate wheat light-carbon synergy to improve photosynthetic efficiency has not been reported. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing amide-silanized fluorescent nanoclusters and their application. The fluorescent nanoclusters (SiANs) achieve precise conversion of ultraviolet light to blue light spectrum (300-400nm→450nm), achieve optimal spectral matching with the chlorophyll absorption curve of the reaction center of wheat leaf photosystem II (PSII), improve the electron transfer rate of photosynthesis, and increase the production of ATP / NADPH, providing energy for the Calvin cycle. As a supplement to light-driven enhancement, SiANs' excellent CO 2 The adsorption capacity provides more raw materials for carbon fixation. This dual-functional design solves the kinetic mismatch problem between the light-dependent reaction and the carbon fixation process, and can effectively achieve the dynamic coupling between the efficiency of the electron transport chain and the enzyme carboxylation rate.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A method for preparing amide-silylated fluorescent nanoclusters, comprising:

[0008] (1) dissolving an amino-functional silane derivative in deionized water, subjecting it to ultrasonic treatment to completely hydrolyze it, adding an ammonium carboxylate salt, and stirring and dissolving the mixture to obtain a precursor solution;

[0009] (2) The precursor solution is transferred to a reactor, heated to react for a period of time, naturally cooled to room temperature, and then filtered through a membrane. The resulting solution is then dialyzed in a dialysis bag, and finally freeze-dried to obtain amide-silanized fluorescent nanoclusters.

[0010] Furthermore, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) characterization confirmed that the surface of the fluorescent nanoclusters was modified with amino groups (-NH 2 ), carboxyl (-COOH) and other hydrophilic nitrogen-containing / oxygen-containing functional groups.

[0011] Furthermore, fluorescence spectroscopy, UV-visible absorption spectroscopy and chronocoulometry analysis showed that the nanocluster has both light conversion properties and carbon dioxide adsorption capacity.

[0012] Furthermore, CCK-8 cytotoxicity experiments showed that the fluorescent nanoclusters exhibited lower physiological toxicity and higher biocompatibility.

[0013] The amide-silanized fluorescent nanoclusters prepared by the present invention have the following effects:

[0014] 1. The spherical nanocluster morphology and particle size distribution are 2.5-4.0nm.

[0015] 2. It can convert ultraviolet light (300-400nm) into blue light (410nm-500nm)

[0016] 3. The interior is linked by a three-dimensional silanized molecular skeleton, and the surface is modified with oxygen-containing and nitrogen-containing groups, such as amino and carboxyl groups.

[0017] 4. With CO 2 Adsorption function: adsorption capacity determined by chronocoulometry ≥ 2.5mmol / g (298K).

[0018] 5. It has low physiological toxicity. During the 48h exposure period, at the test concentration of 5000mg / L, the synthesized SiANs have little effect on the metabolic activity of human bronchial cells (16HBE), and the cell viability is always maintained above 80%.

[0019] Further, the general formula of the amino-functional silane derivative is NH 2 -R-Si-(OR') 3 , wherein R is an organic moiety and R' is a methyl group or an ethyl group.

[0020] Preferably, the amino-functional silane derivative is selected from any one of the following: 3-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-aminoethyl-γ-aminopropyltrimethoxysilane, N-aminoethyl-γ-aminopropylmethyldimethoxysilane.

[0021] Further, the general formula of the ammonium carboxylate salt is (NH 4 ) n [R-(COO - ) n ], wherein R is the organic part of the carboxylic acid other than the carboxyl group, specifically including: an alkyl group, an aryl group or a substituent containing other functional groups, and n is the number of carboxyl groups in the carboxylic acid molecule.

[0022] Furthermore, the ammonium carboxylate salt includes one of ammonium tartrate, ammonium malonate, ammonium succinate, ammonium gluconate, ammonium citrate, ammonium malate and ammonium isocitrate.

[0023] Furthermore, the molar ratio of the amino-functional silane derivative to the ammonium carboxylate salt is 1:(0.1-0.5), preferably 1:0.3.

[0024] Furthermore, the sufficient stirring and dissolving in step (1) is performed by rotor stirring at a rotation speed of 450-550 rpm, preferably 500 rpm.

[0025] Furthermore, the heating reaction in step (2) is carried out at 90-160° C. for 8-12 hours, preferably at 160° C. for 8 hours. Temperature deviation from this range will result in a significant decrease in the fluorescence quantum yield.

[0026] Furthermore, the pore size of the filter membrane in the membrane filtration in step (2) is 0.1-0.5 μm; the dialysis bag is 500 Da-3500 Da, preferably 500 Da.

[0027] Preferably, the freeze-drying temperature in step (2) is -50°C to -40°C.

[0028] Another object of the present invention is to provide the application of the amide-silylated fluorescent nanoclusters prepared by the above-mentioned preparation method of amide-silylated fluorescent nanoclusters in the agricultural field, which can significantly promote the growth and development of wheat seedlings during cultivation.

[0029] Furthermore, mechanism studies have shown that the growth-promoting effect originates from the improvement of the photosynthetic efficiency of wheat seedlings by fluorescent nanoclusters.

[0030] The application method is as follows: spray at the root with a concentration of 1-100 mg / L to enhance crop photosynthesis through the following synergistic mechanisms:

[0031] (a) Light energy conversion: Increase chlorophyll synthesis by 90%; increase the electron transfer rate of photosystem II (PSII) by 40%;

[0032] (b)CO 2 Adsorption: The abundant amino functional groups on the surface of amide-silanized fluorescent nanoclusters form multi-level adsorption sites with dynamic hydrogen bond networks, in which the primary amino groups interact with CO through Lewis acid-base interactions. 2 Chemical adsorption occurs, and the OH…O=C=O hydrogen bonds formed between adjacent molecules further enhance the physical adsorption capacity. This hydrogen bond-electrostatic synergy makes the material resistant to CO 2 The adsorption capacity reaches 2.50mmol / g (298K).

[0033] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0034] The fluorescent nanoclusters prepared by the present invention innovatively integrate the dual functional properties of spectral conversion and gas adsorption, and construct a synergistic mechanism for photosynthesis enhancement. Through precise spectral modulation technology, the material efficiently converts 300-400nm ultraviolet light into 450nm blue light emission, forming an ideal spectral overlap with the absorption band of chlorophyll in the PSII reaction center of wheat leaves, significantly improving the efficiency of light energy conversion. Experiments have confirmed that the nanomaterial can increase the electron transfer rate of photosystem II and build a more efficient energy supply system for the Calvin cycle. As a synergistic mechanism of the light-driven effect, the fluorescent nanoclusters, with their mesoporous surface-modified amino active sites, have excellent CO 2The adsorption capacity provides more raw materials for carbon fixation and effectively activates the catalytic activity of Rubisco carboxylase. This dual-functional design solves the kinetic mismatch problem between the light-dependent reaction and the carbon fixation process, and realizes the dynamic coupling between the efficiency of the electron transport chain and the enzyme carboxylation rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0036] Figure 1 It is the synthesis pathway of SiANs;

[0037] Figure 2 TEM image of SiANs; particle size distribution of SiANs; infrared spectrum of SiANs; x-ray photoelectron spectrum of SiANs;

[0038] Figure 3 3D fluorescence spectrum of SiANs, ultraviolet absorption spectrum of SiANs, carbon dioxide adsorption capacity of SiANs; physiological toxicity of SiANs;

[0039] Figure 4 (a) Photo of wheat seedlings; (b) Comparison of root length, plant height, dry weight and fresh weight; (c) Net photosynthetic rate (Pn); (d) Stomatal conductance (Tr); (e) Chlorophyll; (f) Rubisco carboxylase activity; (g) Rubisco activase activity; (h) DCPIP reduction rate kinetic equation (Hill reaction);

[0040] Figure 5 It is the fluorescence comparison of fluorescent nanoclusters with the same concentration under 360nm ultraviolet light;

[0041] Figure 6 This is the TEM image of Example 3.

[0042] Figure 7 This is the TEM image of Example 4.

[0043] Figure 8 This is the TEM image of Example 5.

[0044] Fig. 9 Comparison of carbon dioxide adsorption capacity between SiANs of Example 1 and Comparative Example 3. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] Example 1

[0047] A specific method for preparing fluorescent nanoclusters comprises:

[0048] 10 mL of N-aminoethyl-γ-aminopropyltrimethoxysilane (DAMO) was dissolved in 50 mL of deionized water, ultrasonicated for 10 min to completely hydrolyze it, and 3.28 g of ammonium citrate was added and stirred thoroughly to dissolve. The precursor solution was transferred to a 100 mL reactor and heated at 160 ° C for 8 h. After cooling naturally to room temperature, it was filtered through a 0.1 μm filter membrane. For further purification, the resulting solution was dialyzed in a 500 Da dialysis bag for 24 h, and finally freeze-dried to obtain fluorescent nanoclusters (SiANs) solid.

[0049] Figure 1 The assembly mechanism of fluorescent nanocluster SiANs is studied. In the heating reaction, the ammonium citrate precursor first dissociates into citrate and ammonium ions, which are then esterified and ammonolyzed to form a fluorescent molecule citrazinic acid with a conjugated π electron system. The amino end of DAMO and the carboxyl group on the citrazinic acid molecule form a covalent cross-linked network through amidation, while the siloxane end constructs a three-dimensional rigid skeleton through hydrolysis and condensation. Based on density functional theory, the B3LYP hybrid functional and the 6-31G(d) basis set were used to optimize the geometry of the molecular ground state. Molecular dynamics simulations show that the assembly process is synergistically regulated by electrostatic interactions and hydrogen bond networks, and the synergistic effect of the silane network and amide bonds ultimately forms a nanocluster with a stable structure.

[0050] Figure 2 The morphology and structure of fluorescent nanocluster SiANs are characterized. The morphology and structure of fluorescent nanocluster SiANs show that they have a unique spherical configuration. TEM analysis shows that SiANs are evenly distributed with an average particle size of 2.29nm, and AFM three-dimensional morphology measures an average height of 2.30nm. The two data are consistent with each other, confirming its three-dimensional spherical characteristics.

[0051] XPS analysis shows that the material has a high nitrogen doping content of 14.7%. In the elemental chemical state analysis, the C1s spectrum shows the presence of CC, CO and C=O bonds in the carbon skeleton, the O1s spectrum confirms the characteristic peak of the Si-O bond (530.8eV), and the Si2p spectrum reveals the presence of Si-O (101.8eV) and Si-C (102.5eV), confirming that silicon atoms are successfully embedded in the carbon skeleton.

[0052] The strong peak at 398.8 eV in the N1s spectrum indicates the effective retention of the precursor primary amine group (CNC), while the CNH bond at 399.8 eV is related. The FTIR spectrum further supports the structural characteristics: 3300 cm -1 The broad peak at 1100 cm -1 The Si-O characteristic vibration peak appears at , which together with the XPS data, provides complete evidence of the silicon-oxygen hybrid structure. The rich oxygen / nitrogen functional groups on the surface of the material not only enhance its hydrophilicity, but also significantly improve its water phase dispersion stability through polarity regulation.

[0053] Figure 3 The performance of fluorescent nanocluster SiANs is characterized. The UV-visible absorption spectrum analysis shows that there are characteristic peaks at 245nm (π-π* transition) and 360nm (n-π* transition), among which the strong absorption in the range of 300-400nm is attributed to the electronic effect of N / O atoms to enhance the UV capture ability. The three-dimensional fluorescence spectrum confirms that SiANs produce 450nm high-intensity blue light emission under 360nm excitation. The Qt based on the diffusion control theory is (1 / 2) Quantitative model successfully analyzed CO 2 Adsorption kinetics of CO on amino-modified SiANs under light 2 The adsorption capacity is 2.63mmol / g, and its surface -NH 2 The dual active sites of -OH synergistically enhance CO 2 Adsorption. Cytotoxicity evaluation showed that after exposure to a concentration of 5000 mg / L for 48 hours, the viability of human bronchial epithelial (16HBE) cells still remained above 80%, confirming that the material has excellent biosafety.

[0054] Example 2

[0055] Application of a fluorescent nanocluster to regulate photosynthetic carbon fixation in wheat growth promotion:

[0056] Wheat was selected as a representative of silicon-loving crops. The wheat growth and cultivation experiment was carried out in a constant temperature incubator. The environmental parameters were set as day and night temperature 25 / 20°C, relative humidity 60%, photoperiod 16h / 8h (day / night), photosynthetically active radiation intensity 180umol·m -2 ·s -1Two-leaf wheat seedlings with uniform phenotypes were selected, and their roots were fixed in a hydroponic device containing 1 / 2 Hoagland nutrient solution. Treatment began after the plants had adapted for 3 days. Five SiANs treatment concentration gradients (1, 5, 10, 50, 100 mg·L -1 ), with ultrapure water treatment as the control (CK). The treatment solution was applied by root spraying, and fresh nutrient solution was replaced every 48 hours to maintain ion balance. Three independent biological replicates were set for each treatment, and each replicate contained 12 seedlings. After 10 days of continuous treatment (the plants entered the tillering stage), samples were collected for phenotypic and photosynthetic physiological index determination. This experimental design strictly controls environmental variables, uses random block arrangement to eliminate edge effects, and ensures data reliability through repeated settings, which is in line with the experimental specifications of plant physiology.

[0057] Figure 4 The fluorescent nanocluster SiANs were applied to the physiological phenotype and photosynthesis parameters of wheat. SiANs treatment significantly promoted the growth and root development of seedlings. SiANs solutions at concentrations of 5, 10, and 100 mg / L increased plant height by 20%, 19%, and 17%, respectively, and root length by 80%, 67%, and 65%, respectively. Especially at a concentration of 5 mg / L, SiANs significantly increased the net photosynthetic rate (45%), stomatal conductance (21%), and chlorophyll content (total chlorophyll increased by 90%).

[0058] Furthermore, SiANs increased the DCPIP reduction rate by 40% in isolated chloroplasts by enhancing light-harvesting ability and enhanced the Rubisco carboxylase activity (90%) and Rubisco activase activity (50%), which was attributed to the CO ions from the surface amino-hydrogen bond network of SiANs. 2 These results show that SiANs not only promote chlorophyll synthesis and accelerate the electron transfer rate, but also optimize the enzyme activity during carbon fixation, thereby improving the overall photosynthesis efficiency and solving the kinetic mismatch between light reaction and carbon fixation. Dynamic coupling between the electron transport chain efficiency and the enzyme carboxylation rate is achieved.

[0059] Example 3

[0060] A specific preparation method of fluorescent nanoclusters:

[0061] Dissolve 10 mL of N-aminoethyl-γ-aminopropyltrimethoxysilane (DAMO) in 50 mL of deionized water, sonicate for 10 min to completely hydrolyze it, add 3.28 g of ammonium citrate, and stir thoroughly to dissolve. Transfer the precursor solution to a 100 mL reactor and heat at 90 ° C for 8 h. After naturally cooling to room temperature, filter through a 0.1 μm filter membrane. For further purification, dialyze the resulting solution in a 500 Da dialysis bag for 24 h, and finally freeze-dry to obtain fluorescent nanoclusters (SiANs) solids. TEM Figure 6 shown.

[0062] Example 4

[0063] A specific preparation method of fluorescent nanoclusters:

[0064] 8.00 mL of 3-aminopropyltrimethoxysilane (APTMS) was dissolved in 50 mL of deionized water, and ultrasonicated for 10 min to completely hydrolyze it. 3.28 g of ammonium malate was added and stirred thoroughly to dissolve. The precursor solution was transferred to a 100 mL reactor and heated at 160 ° C for 8 h. After cooling naturally to room temperature, it was filtered through a 0.1 μm filter membrane. For further purification, the resulting solution was dialyzed in a 500 Da dialysis bag for 24 h, and finally freeze-dried to obtain fluorescent nanoclusters (SiANs) solid. TEM Figure 7 shown.

[0065] Example 5

[0066] A specific preparation method of fluorescent nanoclusters:

[0067] Dissolve 10.00 mL of γ-aminopropyltriethoxysilane (APTES) in 50 mL of deionized water, sonicate for 10 min to completely hydrolyze it, add 3.28 g of ammonium malate, and stir thoroughly to dissolve. Transfer the precursor solution to a 100 mL reactor and heat at 160 ° C for 8 h. After naturally cooling to room temperature, filter through a 0.1 μm filter membrane. For further purification, dialyze the resulting solution in a 500 Da dialysis bag for 24 h, and finally freeze-dry to obtain fluorescent nanoclusters (SiANs) solid. TEM Figure 8 shown.

[0068] Example 6

[0069] A specific preparation method of fluorescent nanoclusters:

[0070] 9.30 mL of N-aminoethyl-γ-aminopropylmethyldimethoxysilane (AEAPS) was dissolved in 50 mL of deionized water, ultrasonicated for 10 min to completely hydrolyze it, and 3.28 g of ammonium tartrate was added and stirred thoroughly to dissolve. The precursor solution was transferred to a 100 mL reactor and heated at 160 ° C for 8 h. After cooling naturally to room temperature, it was filtered through a 0.1 μm filter membrane. For further purification, the resulting solution was dialyzed in a 500 Da dialysis bag for 24 h, and finally freeze-dried to obtain fluorescent nanoclusters (SiANs) solid.

[0071] Figure 5 The fluorescence intensity of Example 1 and Examples 3-6 under 360nm ultraviolet light, all groups have blue fluorescence, it can be seen that the silane coupling agent and temperature in Example 1 are the best choices.

[0072] Comparative Example 1

[0073] A specific preparation method of fluorescent nanoclusters

[0074] Dissolve 4.50 mL of vinyl trimethoxysilane (VTMS) in 50 mL of deionized water, sonicate for 10 min to completely hydrolyze it, add 3.28 g of ammonium citrate, and stir thoroughly to dissolve. Transfer the precursor solution to a 100 mL reactor and heat at 160 ° C for 8 h. After cooling naturally to room temperature, filter through a 0.1 μm filter membrane. For further purification, dialyze the resulting solution in a 500 Da dialysis bag for 24 h, and finally freeze-dry to obtain a fluorescent nanocluster (SiANs) solid.

[0075] Since VTMS is difficult to effectively hydrolyze in water, no fluorescent nanoclusters were generated after the reaction, indicating that it is unable to construct a stable silane network structure.

[0076] Comparative Example 2

[0077] A specific preparation method of fluorescent nanoclusters

[0078] 10.00 mL of N-aminoethyl-γ-aminopropyltrimethoxysilane (DAMO) was dissolved in 50 mL of deionized water, ultrasonicated for 10 min to completely hydrolyze it, and 3.28 g of ammonium citrate was added and stirred thoroughly to dissolve. The precursor solution was transferred to a 100 mL reactor and heated at 60 ° C for 8 h. After cooling naturally to room temperature, it was filtered through a 0.1 μm filter membrane. For further purification, the resulting solution was dialyzed in a 500 Da dialysis bag for 24 h, and finally freeze-dried to obtain fluorescent nanoclusters (SiANs) solid.

[0079] After the reaction was completed, no fluorescent nanoclusters were obtained by freeze drying, and there was no fluorescence under ultraviolet light. The reaction temperature was too low and fluorescent molecular clusters could not be formed.

[0080] Comparative Example 3

[0081] A specific preparation method of fluorescent nanoclusters

[0082] 10.00 mL of 3-aminopropyltrimethoxysilane (APTMS) was dissolved in 50 mL of deionized water, and the mixture was ultrasonicated for 10 min to completely hydrolyze the mixture. 2.59 g of citric acid was added and stirred to dissolve the mixture. The precursor solution was transferred to a 100 mL reactor and heated at 60 ° C for 8 h. After cooling to room temperature naturally, the precursor solution was filtered through a 0.1 μm filter membrane. For further purification, the resulting solution was dialyzed in a 500 Da dialysis bag for 24 h, and finally the fluorescent nanoclusters (SiANs) solid were obtained by freeze drying.

[0083] Figure 6 The carbon dioxide adsorption capacity of SiANs in Example 1 is compared with that of Comparative Example 3. Due to the lack of ammonium ions, the amino groups on the surface of the synthesized fluorescent nanoclusters are greatly reduced, which greatly weakens their carbon dioxide adsorption capacity.

[0084] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0085] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing amide-silanized fluorescent nanoclusters, characterized in that: Ammonium carboxylate salts and amino-functional silane derivatives were used as precursors and reacted under hydrothermal conditions to assemble amide-silanized fluorescent nanoclusters through double interfaces.

2. The method for preparing an amide-silylated fluorescent nanocluster according to claim 1, characterized in that: The preparation method specifically comprises: (1) dissolving an amino-functional silane derivative in deionized water, subjecting it to ultrasonic treatment to completely hydrolyze it, adding an ammonium carboxylate salt, and stirring and dissolving the mixture to obtain a precursor solution; (2) The precursor solution is transferred to a container, heated to react for a period of time, naturally cooled to room temperature, and then filtered through a membrane. The resulting solution is then dialyzed in a dialysis bag, and finally freeze-dried to obtain amide-silanized fluorescent nanoclusters.

3. The method for preparing an amide-silylated fluorescent nanocluster according to claim 2, characterized in that: The general formula of the ammonium carboxylate salt is (NH4)n[R-(COO-)n], wherein R is the organic part of the carboxylic acid except the carboxyl group, specifically including: alkyl, aryl or substituents containing other functional groups, and n is the number of carboxyl groups in the carboxylic acid molecule.

4. The method for preparing an amide-silylated fluorescent nanoclusters according to claim 2, wherein the ammonium carboxylate salt comprises: A type of ammonium tartrate, ammonium malonate, ammonium succinate, ammonium citrate, ammonium gluconate, ammonium malate, and ammonium isocitrate.

5. The method for preparing an amide-silylated fluorescent nanoclusters according to claim 2, wherein the general formula of the amino-functional silane derivative is NH2-R-Si-(OR')3, wherein R is an organic molecular chain and R' is a methyl group or an ethyl group.

6. The method for preparing an amide-silylated fluorescent nanocluster according to claim 2, characterized in that: The amino functional silane derivatives include: 3-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-aminoethyl-γ-aminopropyltrimethoxysilane or N-aminoethyl-γ-aminopropylmethyldimethoxysilane.

7. The method for preparing an amide-silylated fluorescent nanocluster according to claim 2, characterized in that: The molar ratio of the amino-functional silane derivative to the ammonium carboxylate salt in step (1) is 1:(0.1-0.5); The sufficient stirring and dissolving in step (1) is carried out by stirring with a rotor at a rotation speed of 450-550 rpm.

8. The method for preparing an amide-silylated fluorescent nanocluster according to claim 2, characterized in that: The heating reaction in step (2) is carried out at 90-160° C. for 8-12 hours; The pore size of the filtration membrane in the membrane filtration in step (2) is 0.1-0.5 μm; the dialysis bag is 500Da-3500Da.

9. The method for preparing an amide-silylated fluorescent nanocluster according to claim 2, characterized in that: The freeze-drying temperature in step (2) is -50°C to -40°C.

10. An application of amide-silylated fluorescent nanoclusters prepared by the method for preparing amide-silylated fluorescent nanoclusters according to any one of claims 2 to 9 in the field of agriculture, characterized in that: Spraying at the roots at a concentration of 1-100 mg / L can enhance crop photosynthesis through the following synergistic mechanisms: (a) Light energy conversion: Increase chlorophyll synthesis by 80%; increase the electron transfer rate of photosystem II (PSII) by 40%; (b) CO2 adsorption: The abundant amino functional groups on the surface of amide-silanized fluorescent nanoclusters and the dynamic hydrogen bond network form multi-level adsorption sites, among which the primary amino groups chemically adsorb CO2 through Lewis acid-base reaction. At the same time, the OH···O=C=O hydrogen bonds formed between adjacent molecules further enhance the physical adsorption capacity. This hydrogen bond-electrostatic synergistic effect makes the material's CO2 adsorption capacity reach 2.50 mmol / g (298 K).

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