An ACC nanoparticle stabilizer and its application

Abstract

This invention belongs to the field of preparation and stabilization technology of functional inorganic nanocomposites, specifically disclosing an ACC nanoparticle stabilizer and its application. This invention uses a single amino acid such as aspartic acid, glutamic acid, and lysine, or a mixture of multiple amino acids, as the amino acid source, and phosphoric acid solution as the phosphorus source. By controlling the reaction temperature at 130-220℃ and the reaction time at 1-5 hours, hydrothermal polymerization is achieved to prepare ACC nanoparticle stabilizers. The hydrothermal method does not require complex catalysts, has mild reaction conditions, and is suitable for acidic, alkaline, and mixed amino acid systems, exhibiting strong versatility. The hydrothermal product can be directly concentrated and used without separation and purification, which not only reduces preparation costs but also helps improve the stability of ACC nanoparticles, solving the problem of insufficient long-term stability and easy crystallization of ACC nanoparticles. It has the advantages of being green and efficient, highly controllable, and biosafe.

Description

Technical Field

[0001] This invention belongs to the field of preparation and stabilization technology of functional inorganic nanocomposites, specifically relating to an ACC nanoparticle stabilizer and its application in stabilizing ACC nanoparticles. Background Technology

[0002] Amorphous calcium carbonate (ACC), as a metastable form of calcium carbonate, possesses high specific surface area, high reactivity, and good biocompatibility, making it valuable for applications in drug carriers, cosmetic additives, and food preservation. However, ACC suffers from poor thermodynamic stability and readily transforms into a crystalline state (calcite, aragonite, etc.), limiting its practical applications. To address this issue, Chinese patent CN108778296B (Amorphical) discloses a stabilizer-stabilized amorphous calcium carbonate. The stabilizer is selected from polyphosphates, phosphorylated amino acids, organic acids, phosphorylated peptides, phosphate or sulfate esters of hydroxycarboxylic acids, sugars, or combinations thereof, and can be used to prepare drugs for treating Duchenne muscular dystrophy (DMD). Furthermore, existing research indicates that polyamino acids or phosphorylated polyamino acids can inhibit ACC crystallization through surface adsorption and charge repulsion, making them ideal ACC stabilizers. For example, in their study entitled "Stabilization and crystallization mechanism of amorphous calciumcarbonate" (Journal of Colloid and Interface Science, Volume 680, Part B, 15 February 2025, Pages 24-35), Wang, Q. et al. systematically investigated the effects of polyaspartic acid (pAsp) with different chain lengths on the ACC crystallization process. Their study indicated that although pAsp can inhibit ACC crystallization to some extent, its effect is strongly dependent on the polymer chain length and concentration, and fine-tuning the ACC crystallization mechanism remains challenging, particularly in achieving a controllable transformation to a specific crystalline phase and morphology. Therefore, current technology still lacks a method to efficiently and stably control the ACC crystallization process and achieve selective generation of specific crystalline phases.

[0003] Furthermore, the aforementioned ACC stabilizers typically suffer from complex preparation methods, poor versatility, and short stabilization times for ACC nanoparticles. Moreover, traditional stabilizers require separation and purification before use in ACC nanoparticle preparation, increasing process costs and operational complexity. Therefore, there is an urgent need to develop a mild, efficient, universal, and long-lasting method for preparing ACC nanoparticles, thereby simplifying the process and reducing costs. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide an amorphous calcium carbonate (ACC) nanoparticle stabilizer and its preparation method. This invention solves the problems of complex operation and poor versatility of traditional preparation methods. After hydrothermal reaction, no separation and purification are required, all reaction products are retained, ensuring the controllability and practicality of the method, and also achieving long-term stability of ACC nanoparticles.

[0005] Secondly, this invention provides an application of an ACC nanoparticle stabilizer in stabilizing ACC nanoparticles, which extends their storage period by inhibiting the ACC crystallization transformation.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solutions:

[0007] An ACC nanoparticle stabilizer, the preparation method of which includes the following steps:

[0008] The amino acid raw material is mixed evenly with the phosphoric acid solution, and then subjected to hydrothermal reaction at 130-220℃ for 1-5 hours. The mixture is then concentrated to obtain the final product.

[0009] In a preferred embodiment of the present invention, the amino acid raw material is an acidic amino acid and / or a basic amino acid, selected from any one or more of 20 amino acids.

[0010] Specifically, the amino acid raw materials are selected from one or more of aspartic acid (acidic), glutamic acid (acidic), and lysine (basic). Among them, basic amino acids such as lysine undergo dehydration condensation with phosphoric acid to form phosphorus-doped polymers, while acidic amino acids such as aspartic acid and glutamic acid form a series of different polymers through intramolecular cyclization, ring-opening polymerization, and other reactions.

[0011] In a preferred embodiment of the present invention, the ratio of the amino acid raw material to the phosphoric acid solution is 0.005-0.015 mol: 1 mL, and the mass concentration (w / w) of the phosphoric acid solution is 40%-60%, preferably 50%.

[0012] In a preferred embodiment of the present invention, the product of the hydrothermal reaction is directly concentrated to 1 / 10-1 / 2 of its original volume without separation and purification. The concentration process only requires heating and evaporating the solvent at the original hydrothermal temperature, without the need for rotary evaporation at low temperatures. The temperature, time, and concentration ratio of the hydrothermal reaction should be appropriately adjusted according to the different types of amino acids: for example, the minimum temperature for the hydrothermal reaction of glutamic acid can be lowered to 130℃, the minimum temperature for the hydrothermal reaction of aspartic acid can be lowered to 160℃, while the minimum temperature for the hydrothermal reaction of lysine needs to be higher than 160℃.

[0013] Application of an ACC nanoparticle stabilizer in stabilizing ACC nanoparticles.

[0014] As a preferred embodiment of the present invention, the application includes the following steps:

[0015] The ACC nanoparticle stabilizer was mixed with calcium chloride solution and reacted with sodium carbonate solution under ice-water bath conditions to prepare ACC nanoparticles.

[0016] In a preferred embodiment of the present invention, the volume ratio of the ACC nanoparticle stabilizer to the calcium chloride solution is 1:5-15, and the concentration of the calcium chloride solution is 0.05-0.15 mol / L. After mixing, the mixture is pre-cooled to 4°C (30 min) and rapidly mixed with the sodium carbonate solution under ice-water bath conditions, immediately producing a white precipitate to inhibit ACC crystallization.

[0017] Specifically, for ACC nanoparticle stabilizers prepared with basic amino acids, the pH value is adjusted to 2-3 with phosphoric acid after mixing with calcium chloride solution to avoid premature precipitation; for ACC nanoparticle stabilizers prepared with acidic amino acids, the pH value is adjusted to 1.90-5.63 with sodium hydroxide after mixing with calcium chloride solution to optimize the stabilizer adsorption effect.

[0018] In a preferred embodiment of the present invention, the molar ratio of calcium chloride to sodium carbonate is 1:1-1.05, and the concentration of the sodium carbonate solution is 0.05-0.15 mol / L.

[0019] As a preferred embodiment of the present invention, after reaction under ice-water bath conditions (e.g., 0-5℃), impurities are removed by filtration and washing, and then freeze-drying is performed to retain the amorphous structure of ACC.

[0020] Specifically, the washing process involves washing with deionized water and anhydrous ethanol 1-3 times each.

[0021] Specifically, the freeze-drying process involves freeze-drying at -50°C and a vacuum of 10 Pa for 20-30 hours.

[0022] An ACC nanoparticle comprising the ACC nanoparticle stabilizer.

[0023] The beneficial effects of this invention are:

[0024] This invention uses a single amino acid such as aspartic acid, glutamic acid, and lysine, or a mixture of multiple amino acids, as the amino acid source, and phosphoric acid solution as the phosphorus source. By controlling the reaction temperature of 130-220℃ and the reaction time of 1-5h, hydrothermal polymerization is used to prepare ACC nanoparticle stabilizers. The hydrothermal method does not require complex catalysts, has mild reaction conditions, and is suitable for acidic, alkaline, and mixed amino acid systems, making it highly versatile. The hydrothermal products can be directly concentrated and used without separation and purification, which not only reduces the preparation cost but also helps to improve the stability of ACC nanoparticles.

[0025] The ACC nanoparticle stabilizer prepared by this invention binds to calcium ions on the surface of ACC nanoparticles through electrostatic, hydrogen bonding, and steric hindrance interactions. The phosphorus-doped structure also exhibits stronger coordination bonding, which further enhances the adsorption effect. The ACC nanoparticles prepared in this way maintain a good amorphous morphology after 210 days of storage and have high biocompatibility. Transmission electron microscopy shows that the particle size of the ACC nanoparticles after storage is about 20-50 nm, and they have a porous structure. They have potential advantages in drug carriers, catalysis, adsorption and other fields, and provide technical support for the large-scale application of ACC nanoparticles. Attached Figure Description

[0026] Figure 1 This is the XRD pattern of ACC nanoparticle sample 1 in Example 1.

[0027] Figure 2 This is the XRD pattern of ACC nanoparticle sample 2 in Example 2.

[0028] Figure 3 This is the XRD pattern of ACC nanoparticle sample 3 in Example 3.

[0029] Figure 4 This is the XRD pattern of ACC nanoparticle sample 4 in Example 4.

[0030] Figure 5 This is the XRD pattern of ACC nanoparticle sample 1 in Example 1 after 210 days of storage.

[0031] Figure 6 This is the XRD pattern of ACC nanoparticle sample 2 after 210 days of storage in Example 2.

[0032] Figure 7 This is the XRD pattern of ACC nanoparticle sample 3 in Example 3 after 210 days of storage.

[0033] Figure 8 This is the XRD pattern of ACC nanoparticle sample 4 in Example 4 after 210 days of storage.

[0034] Figure 9 This is the FT-IR spectrum of the macromolecules in the hydrothermal products of Example 1.

[0035] Figure 10 This is the FT-IR spectrum of the macromolecules in the hydrothermal products of Example 2.

[0036] Figure 11 This is the FT-IR spectrum of the macromolecules in the hydrothermal products of Example 3.

[0037] Figure 12 It is the macromolecule in the hydrothermal product of Example 1 1 H-NMR spectrum.

[0038] Figure 13 It is the macromolecule in the hydrothermal product of Example 1 13 C-NMR spectrum.

[0039] Figure 14 It is the macromolecule in the hydrothermal products of Example 2. 1 H-NMR spectrum.

[0040] Figure 15 It is the macromolecule in the hydrothermal products of Example 2. 13 C-NMR spectrum.

[0041] Figure 16 It is the macromolecule in the hydrothermal product of Example 3. 1 H-NMR spectrum.

[0042] Figure 17 It is the macromolecule in the hydrothermal product of Example 3. 31 P-NMR image.

[0043] Figure 18 It is the macromolecule in the hydrothermal product of Example 3. 13 C-NMR spectrum.

[0044] Figure 19 This is a TEM image of ACC nanoparticle sample 1 from Example 1 after 210 days of storage.

[0045] Figure 20 This is a TEM image of ACC nanoparticle sample 2 after 210 days of storage in Example 2.

[0046] Figure 21 This is a TEM image of ACC nanoparticle sample 3 in Example 3 after 210 days of storage.

[0047] Figure 22 This is the SAED (Self-Organizational Electron Diffraction) pattern of ACC nanoparticle sample 1 after 210 days of storage in Example 1.

[0048] Figure 23 This is a SAED image of ACC nanoparticle sample 2 after 210 days of storage in Example 2.

[0049] Figure 24 This is a SAED image of ACC nanoparticle sample 3 in Example 3 after 210 days of storage. Detailed Implementation

[0050] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments and experimental examples. However, those skilled in the art should understand that the embodiments are only used to illustrate the technical solution of the present invention and should not be regarded as limiting the scope of protection of the present invention. Based on the following embodiments, all other implementation schemes obtained by those skilled in the art without creative effort, such as implementation schemes obtained by modification, variation or simple substitution, should fall within the scope of protection of the present invention.

[0051] Unless otherwise specified, the raw materials, instruments, etc. used in the following examples and comparative examples are all commonly used in the art and commercially available to the public. Unless otherwise specified, the experimental methods used in the experimental examples are conventional methods, and the terms and abbreviations used have their conventional meanings in the art.

[0052] Example 1

[0053] This embodiment provides an ACC nanoparticle stabilizer and its preparation method, including the following steps:

[0054] S1: Weigh 0.005 mol of aspartic acid (0.665 g) and add it to a 100 mL flask. Add 40 mL of deionized water and 0.5 mL of 50% phosphoric acid solution, and stir magnetically for 30 min until completely dissolved.

[0055] S2: Transfer the solution to a 100mL hydrothermal reactor, seal it, and place it in an oven. React at 160℃ for 3 hours. After the reaction is complete, allow it to cool naturally to room temperature to obtain a mixture containing hydrothermal products.

[0056] S3: The mixture is concentrated to 1 / 2 of its original volume by heating and evaporation (160℃) to obtain ACC nanoparticle stabilizer.

[0057] This embodiment also provides an application of an ACC nanoparticle stabilizer in stabilizing ACC nanoparticles, including the following steps:

[0058] A1: Mix 2 mL of ACC nanoparticle stabilizer with 20 mL of 0.1 mol / L calcium chloride solution, adjust the pH to 3.01 with 1 mol / L sodium hydroxide solution to obtain mixture A; prepare 20 mL of 0.1 mol / L sodium carbonate solution as solution B; pre-cool mixture A and solution B in a refrigerator at 4℃ for 30 min;

[0059] A2: Under ice-water bath conditions (0-5℃), quickly pour mixture A and solution B into a beaker and stir magnetically for 1 minute. A white precipitate will be produced immediately.

[0060] A3: The precipitate was filtered through a 0.22 μm filter membrane and washed three times each with 10 mL of deionized water and 10 mL of anhydrous ethanol. The precipitate was then transferred to a freeze dryer (-50℃, 10 Pa) and dried for 24 h to obtain ACC nanoparticle sample 1.

[0061] Performance testing:

[0062] (1) XRD analysis: Sample 1 showed no sharp peaks near 2θ=29.5°, exhibiting typical amorphous characteristics. Figure 1 ).

[0063] (2) Long-term stability: After 210 days of sealed storage at room temperature, XRD testing showed no crystallization peaks. Figure 5 ( ), still remains in amorphous form.

[0064] (3) TEM Figure 19 ) and SEDA ( Figure 22 Analysis: After 210 days of storage, the particle size was approximately 20-50 nm, with only a certain degree of aggregation and no obvious large-size crystal growth, indicating that ACC nanoparticles have good anti-aggregation and anti-crystallization stability. The porous structure indicates that the ACC nanoparticles did not undergo significant Ostwald ripening (i.e., small particle dissolution and large particle growth) or fusion crystallization after 210 days of storage, which is indirect evidence that the nanoparticles maintain their nanoscale and amorphous morphology, and also shows the potential advantages of ACC nanoparticles in applications such as drug carriers, catalysis, and adsorption. SEDA showed a broad, diffuse halo ring without sharp crystal diffraction spots or rings, consistent with the XRD analysis results, indicating that the sample still maintains an amorphous morphology and has not undergone a phase transition to crystalline calcium carbonate such as calcite or aragonite, proving the structural stability of the ACC nanoparticles.

[0065] Identification of macromolecules in hydrothermal products:

[0066] FT-IR ( Figure 9 ) and NMR spectra ( Figure 12 , 13 Analysis (using DMSO-d6 as solvent): The mixture containing hydrothermal products was dialyzed through a dialysis bag (MWCO 500) to remove unreacted small molecule compounds. The mixture was then further concentrated, freeze-dried, and the reaction products were measured using FT-IR and NMR. 1 1H NMR characteristics (7.0 ppm singlet peak is the only product peak), 13 C10 NMR characteristics (peaks at 166 ppm and 134 ppm), no signal in the P10 spectrum, FT-IR characteristic region of amide bond and carbonyl (C=O) (~1672 cm⁻¹). -1 ~1424cm -1 ), hydroxyl and NH vibrational region (~3426cm) -1), aliphatic CH vibration region (~2950-2850cm) -1 ), fingerprint region characteristic peak (~1424cm) -1 and ~1278cm -1 ~1200-1100cm -1 This indicates that aspartic acid undergoes intramolecular dehydration cyclization and ring-opening amide bond polymerization under hydrothermal conditions to form high molecular weight poly(pyroaspartic acid), and phosphoric acid does not participate in the formation of a stable phosphorus hybrid structure.

[0067] Example 2

[0068] This embodiment provides an ACC nanoparticle stabilizer and its preparation method, including the following steps:

[0069] S1: Weigh 0.005 mol of glutamic acid (0.735 g) into a 100 mL flask, add 40 mL of deionized water and 0.5 mL of 50% phosphoric acid solution, and stir until dissolved;

[0070] S2: Transfer the solution to a hydrothermal reactor and react at 130°C for 1 hour. After cooling, a mixture containing hydrothermal products is obtained.

[0071] S3: Concentrate the mixture to 1 / 5 of its original volume to obtain ACC nanoparticle stabilizer.

[0072] This embodiment also provides an application of an ACC nanoparticle stabilizer in stabilizing ACC nanoparticles, including the following steps:

[0073] A1: Mix 2 mL of ACC nanoparticle stabilizer with 15 mL of 0.1 mol / L calcium chloride solution, adjust the pH to 3.48 with 1 mol / L sodium hydroxide solution to obtain mixture A; prepare 15 mL of 0.1 mol / L sodium carbonate solution as solution B, and pre-cool at 4℃;

[0074] A2: Under ice-water bath conditions, quickly pour mixture A and solution B into a beaker and stir magnetically for 1 minute. A white precipitate will immediately form.

[0075] A3: The precipitate was filtered through a 0.22 μm filter membrane and washed three times each with 10 mL of deionized water and 10 mL of anhydrous ethanol. The precipitate was then transferred to a freeze dryer (-50℃, 10 Pa) and dried for 24 h to obtain ACC nanoparticle sample 2.

[0076] Performance testing:

[0077] (1) XRD analysis: Sample 2 showed obvious amorphous characteristics ( Figure 2 ).

[0078] (2) Long-term stability: After 210 days of storage, the XRD pattern showed no significant changes. Figure 6 It exhibits excellent stability.

[0079] (3) TEM Figure 20 ) and SEDA ( Figure 23 Analysis: After 210 days of storage, the particle size was 20-50 nm, with only a certain degree of aggregation and no obvious large-size crystal growth, indicating that ACC nanoparticles have good anti-aggregation and anti-crystallization stability. The porous structure indicates that the ACC nanoparticles did not undergo obvious Ostwald ripening or fusion crystallization after 210 days of storage, which is indirect evidence that the nanoparticles maintain their nanoscale and amorphous morphology, and also shows the potential advantages of ACC nanoparticles in drug carrier, catalysis, adsorption and other applications. SEDA showed a broad, diffuse halo ring without sharp crystal diffraction spots or rings, consistent with the XRD analysis results, indicating that the sample still maintains its amorphous morphology and has not undergone phase transition, proving the structural stability of the ACC nanoparticles.

[0080] Identification of macromolecules in hydrothermal products:

[0081] FT-IR ( Figure 10 ) and NMR spectra ( Figure 14 , 15 Analysis (using DMSO-d6 as solvent): The mixture containing hydrothermal products was treated using the same separation and purification method as in Example 1, followed by FT-IR and NMR measurements. The NMR 1H spectrum showed characteristic features (a singlet peak at 3.6 ppm was the only product peak), and the P spectrum showed no signal. The FT-IR spectrum showed characteristic regions of amide bonds and carbonyl groups (C=O) (~1650 cm⁻¹). -1 ~1550cm -1 The vibrational region of hydroxyl and NH (~3400-3200cm) -1 ), aliphatic CH vibration region (~2950-2850 cm) -1 ), fingerprint region characteristic peak (~1450cm) -1 and ~1380cm -1 ~1200-1100cm -1 This indicates that glutamic acid undergoes intramolecular dehydration cyclization and ring-opening amide bond polymerization under hydrothermal conditions to form high molecular weight poly(pyroglutamic acid), and phosphoric acid does not participate in the formation of a stable phosphorus hybrid structure.

[0082] Example 3

[0083] This embodiment provides an ACC nanoparticle stabilizer and its preparation method, including the following steps:

[0084] S1: Weigh 0.005 mol of lysine (0.735 g) and add it to a 100 mL flask. Add 40 mL of deionized water and 0.5 mL of 50% phosphoric acid solution, and stir to dissolve.

[0085] S2: Transfer the solution to a hydrothermal reactor and react at 220°C for 3 hours. After cooling, a mixture containing hydrothermal products is obtained.

[0086] S3: Concentrate the mixture to 1 / 5 of its original volume to obtain ACC nanoparticle stabilizer.

[0087] This embodiment also provides an application of an ACC nanoparticle stabilizer in stabilizing ACC nanoparticles, including the following steps:

[0088] A1: Mix 2 mL of ACC nanoparticle stabilizer with 20 mL of 0.1 mol / L calcium chloride solution, adjust the pH to 2.98 with phosphoric acid to obtain mixture A; prepare 20 mL of 0.1 mol / L sodium carbonate solution as solution B, and pre-cool at 4℃;

[0089] A2: Under ice-water bath conditions, quickly pour mixture A and solution B into a beaker and stir magnetically for 1 minute. A white precipitate will immediately form.

[0090] A3: The precipitate was filtered through a 0.22 μm filter membrane and washed three times each with 10 mL of deionized water and 10 mL of anhydrous ethanol. The precipitate was then transferred to a freeze dryer (-50℃, 10 Pa) and dried for 24 h to obtain ACC nanoparticle sample 3.

[0091] Performance testing:

[0092] (1) XRD analysis: Sample 3 showed significant amorphous characteristics ( Figure 3 ).

[0093] (2) Long-term stability: After 210 days of storage, it still maintains an amorphous form. Figure 7 ).

[0094] (3) TEM Figure 21 ) and SEDA ( Figure 24 Analysis: The analysis results are basically the same as above.

[0095] Identification of macromolecules in hydrothermal products:

[0096] FT-IR ( Figure 11 ) and NMR spectra ( Figure 16-18 (D2O as solvent) Analysis: The mixture containing hydrothermal products was treated using the same separation and purification method as in Example 1, and then FT-IR and NMR were measured. The FT-IR spectrum showed a value of 3500 cm⁻¹. -1 The broad peaks in the vicinity correspond to the OH stretching vibration, possibly originating from the hydroxyl group (-PO3H2) of the phosphate group or the water of crystallization in the product. (3000-2800 cm⁻¹) -1Peak: Belongs to the CH stretching vibration. Combined with the presence of the aliphatic chain methylene peak (δ~1.5-1.8ppm) in the 1H NMR spectrum and the aliphatic chain carbon peak (δ~20-40ppm) in the 1C NMR spectrum, this indicates that the alkyl chain structure of lysine is largely preserved. 1600-1500cm -1 Regional peaks: correspond to NH bending vibrations or C=O stretching vibrations, combined with... 13 The carbonyl characteristic peak at δ~170-180 ppm in C NMR indicates that lysine molecules form amide bonds through the condensation of amino and carboxyl groups (amide bond, -CONH-). (1200-1000 cm⁻¹) -1 Dense peaks: These belong to the stretching vibrations of PO or PN, clearly indicating that the product contains a phosphate ester or phosphorus heterocyclic structure, which is consistent with... 31 The corresponding peaks in the δ~1.5ppm P NMR spectrum indicate that phosphoric acid and the amino group of lysine underwent dehydration condensation, forming a phosphorus hybrid structure. In summary, this product is a phosphoric acid-modified derivative of ε-polylysine formed by the condensation and polymerization of lysine and phosphoric acid under hydrothermal conditions. That is, some of the side chain amino groups on the ε-polylysine backbone underwent protonation or covalent bonding with phosphoric acid.

[0097] Example 4

[0098] This embodiment provides an ACC nanoparticle stabilizer and its preparation method, including the following steps:

[0099] S1: Weigh 0.005 mol of mixed amino acids (0.005 / 3 mol each of aspartic acid, glutamic acid, and lysine) into a 100 mL flask, add 40 mL of deionized water and 0.5 mL of 50% phosphoric acid solution, and stir to dissolve;

[0100] S2: Transfer the solution to a hydrothermal reactor and react at 220°C for 1 hour. After cooling, a mixture containing hydrothermal products is obtained.

[0101] S3: Concentrate to 1 / 2 of the original volume to obtain ACC nanoparticle stabilizer.

[0102] This embodiment also provides an application of an ACC nanoparticle stabilizer in stabilizing ACC nanoparticles, including the following steps:

[0103] A1: Mix 2 mL of ACC nanoparticle stabilizer with 20 mL of 0.1 mol / L calcium chloride solution, adjust the pH to 3.64 to obtain mixture A; prepare 20 mL of 0.1 mol / L sodium carbonate solution as solution B, and pre-cool at 4℃;

[0104] A2: Under ice-water bath conditions (0-5℃), quickly pour mixture A and solution B into a beaker and stir magnetically for 1 minute. A white precipitate will be produced immediately.

[0105] A3: The precipitate was filtered through a 0.22 μm filter membrane and washed three times each with 10 mL of deionized water and 10 mL of anhydrous ethanol. The precipitate was then transferred to a freeze dryer (-50℃, 10 Pa) and dried for 24 h to obtain ACC nanoparticle sample 4.

[0106] Performance testing:

[0107] (1) XRD analysis: Sample 4 has a stable amorphous structure. Figure 4 ).

[0108] (2) Long-term stability: After 210 days of storage, no crystallization peak was observed in the XRD pattern. Figure 8 This confirms the stabilizing effect of the mixed system.

[0109] Performance characterization and stability verification results:

[0110] Phase analysis: The amorphous morphology of ACC was characterized by X-ray diffraction (XRD). The amorphous sample showed no sharp crystalline peaks near 2θ=29.5°.

[0111] Long-term stability: After 210 days of sealed storage at room temperature, monthly XRD tests showed that the sample still maintained an amorphous morphology.

[0112] In summary, this invention verifies the effectiveness of hydrothermal products from different amino acid systems in the preparation of ACC nanoparticles and their long-term stabilizing effect through four embodiments. Whether using acidic amino acids (aspartic acid, glutamic acid), basic amino acids (lysine), or mixed amino acid systems, ACC nanoparticles can be prepared, ensuring that the ACC nanoparticles have an amorphous morphology. The long-term stability test results show that the ACC nanoparticles prepared by the method of this invention remain stable for 210 days, providing reliable support for their practical application.

[0113] In other embodiments of the present invention, the process parameters in the preparation method of ACC nanoparticle stabilizer can be arbitrarily adjusted within a given range without significantly affecting the amorphous morphology and long-term stability of ACC.

[0114] Although the technical solution of the present invention has been described in detail above with general descriptions, specific embodiments, and experimental examples, it should be noted that the embodiments and experimental examples are only used to illustrate the technical solution and technical effects of the present invention, and should not be regarded as any limitation on the scope of protection of the present invention. Simple modifications, alterations, or improvements made based on the technical concept of the present invention are all within the scope of protection claimed by the present invention.

Claims

1. An ACC nanoparticle stabilizer, characterized in that: Its preparation method includes the following steps: The amino acid raw material is mixed evenly with the phosphoric acid solution, and then subjected to hydrothermal reaction at 130-220℃ for 1-5 hours. The mixture is then concentrated to obtain the final product.

2. The ACC nanoparticle stabilizer according to claim 1, characterized in that: The amino acid raw material is an acidic amino acid and / or a basic amino acid, selected from any one or more of 20 amino acids.

3. The ACC nanoparticle stabilizer according to claim 1 or 2, characterized in that: The amino acid raw material is selected from one or more of aspartic acid, glutamic acid, and lysine.

4. The ACC nanoparticle stabilizer according to claim 1, characterized in that: The ratio of amino acid raw material to phosphoric acid solution is 0.005-0.015 mol: 1 mL, and the mass concentration (w / w) of phosphoric acid solution is 40%-60%.

5. The ACC nanoparticle stabilizer according to claim 1, characterized in that: The products of the hydrothermal reaction are directly concentrated to 1 / 10-1 / 2 of their original volume without separation or purification.

6. The use of an ACC nanoparticle stabilizer as described in any one of claims 1-5 in stabilizing ACC nanoparticles.

7. The application according to claim 6, characterized in that: The application includes the following steps: The ACC nanoparticle stabilizer was mixed with calcium chloride solution and reacted with sodium carbonate solution under ice-water bath conditions to prepare ACC nanoparticles.

8. The application according to claim 7, characterized in that: The volume ratio of the ACC nanoparticle stabilizer to the calcium chloride solution is 1:5-15, and the concentration of the calcium chloride solution is 0.05-0.15 mol / L.

9. The application according to claim 7, characterized in that: The molar ratio of calcium chloride to sodium carbonate is 1:1-1.05, and the concentration of the sodium carbonate solution is 0.05-0.15 mol / L.

10. An ACC nanoparticle, characterized in that: It contains the ACC nanoparticle stabilizer as described in any one of claims 1-5.

Images