Composite ice nucleating material, and preparation method and application thereof

Abstract

The present application relates to the technical field of artificial ice nucleating material, and more particularly to a composite ice nucleating material, a preparation method and application thereof.The composite ice nucleating material comprises ice nucleation protein and nano silver iodide particles complexed on the surface of the ice nucleation protein.The composite ice nucleating material provided by the present application has excellent performance of high nucleation threshold temperature and fast nucleation rate, and can exhibit excellent intervention effect in the core temperature zone of freezing rain intervention, thereby effectively reducing freezing rain disasters.

Description

Technical Field

[0001] This invention relates to the field of artificial ice core materials technology, and in particular to a composite ice core material, its preparation method, and its application. Background Technology

[0002] Freezing rain is a hazardous weather phenomenon originating from a specific atmospheric structure. Its typical characteristic is the presence of a warm layer in the middle atmosphere with temperatures above 0°C, keeping precipitation in a liquid state. When raindrops fall and pass through a thin layer of cold air near the ground with temperatures below 0°C, they cool into supercooled water droplets. These supercooled water droplets freeze instantly upon contact with the ground or objects below 0°C, forming a hard, smooth ice layer that poses a serious threat to infrastructure such as power grids, transportation, and communications.

[0003] An effective way to proactively intervene in freezing rain disasters is to seed highly efficient artificial ice nuclei into the near-surface cold layer, inducing supercooled water droplets to freeze into ice crystals, ice particles, or snowflakes in the air before impact. This strategy not only directly avoids impact freezing but also slightly improves local temperatures through the latent heat released by the supercooled water-ice phase transition, and causes precipitation to fall in a more easily preventable solid form, thus significantly reducing the risk of disasters. However, the most widely used artificial ice nuclei material is currently silver iodide (AgI). Its crystal structure closely matches that of ice, making it an excellent heterogeneous nucleation template, but its efficient nucleation activity strongly depends on sufficiently low temperatures. Experiments and observations show that large-scale activation of AgI typically requires temperatures below -7°C or even -10°C. However, within the critical temperature range of -1°C to -5°C, common in freezing rain cold layers, the nucleation efficiency of AgI drops sharply, requiring extremely large seeding doses, often with poor results or even complete failure.

[0004] On the other hand, naturally occurring ice nucleoproteins (INPs, such as those derived from Pseudomonas syringae) exhibit the ability to initiate ice crystal formation at relatively high temperatures (e.g., -2°C to -4°C). However, as biological materials, they suffer from relatively weak environmental stability and sometimes limited nucleation rates when used alone.

[0005] Therefore, developing a novel material capable of achieving precise and robust composite of AgI and INP at the molecular / nanoscale, exhibiting a definite and significant synergistic effect in the core temperature range of freezing rain intervention (-1℃ to -5℃), and its reliable and reproducible preparation method, has become an urgent need to break through the current bottleneck of artificial freezing rain intervention technology. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a composite ice core material, its preparation method, and its applications. The composite ice core material provided by this invention possesses excellent properties, including a high nucleation threshold temperature (above -4℃) and a fast nucleation rate. It exhibits superior intervention effects in the core temperature range (-1℃ to -5℃) of freezing rain intervention, thereby effectively reducing freezing rain disasters.

[0007] In a first aspect, the present invention provides a composite ice core material, the composite ice core material comprising an ice core protein and nano-silver iodide particles complexed on the surface of the ice core protein.

[0008] The composite ice core material provided by this invention combines the excellent properties of ice core proteins and silver iodide, exhibiting both a high nucleation threshold temperature (above -4℃) and a fast nucleation rate. It demonstrates excellent intervention effects in the core temperature range (-1℃ to -5℃) of freezing rain intervention, thereby effectively reducing freezing rain disasters. Specifically: The composite ice nucleus material provided by this invention includes ice nucleus protein and nano-silver iodide particles complexed on the surface of the ice nucleus protein. This structure allows water molecule clusters pre-organized by the ice nucleus protein at higher temperatures (above -4°C) to be immediately guided into ice crystals by neighboring AgI particles with highly matched crystal lattices. This achieves a rapid relay from "pre-organization" to "lattice guidance," thereby raising the active temperature threshold for efficient nucleation of the composite ice nucleus material to above -4°C and significantly accelerating the nucleation kinetics process. It exhibits excellent nucleation rate and, when seeded into the near-surface cold layer, demonstrates excellent freezing rain intervention, significantly outperforming traditional silver iodide materials and solving the problem of low catalytic efficiency of traditional ice nucleus materials.

[0009] As a preferred embodiment of the present invention, the molar ratio of silver iodide to ice nucleus protein in the composite ice nucleus material is 10-50:1, for example, 10:1, 20:1, 30:1, 40:1, 50:1, etc.

[0010] When the molar ratio of silver iodide to ice nucleoprotein is within the above range, the nano-silver iodide particles form a uniform, high-density monolayer on the surface of the ice nucleoprotein. The two work synergistically to achieve a high nucleation threshold temperature (above -4℃) and a fast nucleation rate.

[0011] As a preferred embodiment of the present invention, the average particle size of the nano-silver iodide particles is 10-50 nm, such as 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, etc.

[0012] As a preferred embodiment of the present invention, the ice nucleus protein is selected from any one or more of bacterial ice nucleus proteins, fungal ice nucleus proteins, or recombinant ice nucleus proteins.

[0013] As a preferred embodiment of the present invention, the ice nucleus protein is derived from *Pseudomonas syringae*, *Pseudomonas fluorescens*, *Erwinia gracilis*, or *Xanthomonas campestris*.

[0014] As a preferred embodiment of the present invention, the ice nucleus protein exists in the form of purified protein, bacterial extract, or inactivated bacterial powder.

[0015] Secondly, the present invention provides a method for preparing the composite ice core material as described in the first aspect, the method comprising the following steps: (1) Dissolve the ice nucleoprotein in a solvent to obtain an ice nucleoprotein solution; (2) Silver nitrate was added dropwise to the ice nucleoprotein solution to obtain ice nucleoprotein-Ag. + Precursor solution; (3) Add water-soluble metal iodide dropwise to the ice nucleoprotein-Ag + The precursor solution was purified to obtain the composite ice core material.

[0016] The preparation method provided by this invention achieves efficient composite of two phases at the nanoscale by guiding in situ synthesis of silver iodide nanoparticles on the surface of ice nuclei proteins. This generates a quantitatively verifiable nucleation synergistic effect, effectively improving the nucleation threshold temperature and nucleation rate of the composite ice nuclei material, and breaking through the performance limitations of simple physical mixing.

[0017] As a preferred embodiment of the present invention, step (1) is performed at 0-4°C (e.g., 0°C, 1°C, 2°C, 3°C, 4°C, etc.) to maximize the preservation of the native conformation and activity of the ice nucleoprotein. It is understood that the solvent in step (1) is a pre-cooled solvent to ensure the native conformation and activity of the ice nucleoprotein.

[0018] As a preferred embodiment of the present invention, the concentration of the ice nucleoprotein solution is 1.0-5.0 mg / mL, such as 1.0 mg / mL, 2.0 mg / mL, 3.0 mg / mL, 4.0 mg / mL, 5.0 mg / mL, etc.

[0019] The concentration of the ice nucleoprotein solution within the above range ensures that the ice nucleoprotein molecules are fully dispersed in the solvent, thereby fully exposing the active sites on its surface for pre-organizing water molecules (such as regularly arranged carboxyl groups, hydrophobic patches formed by the aggregation of multiple hydrophobic groups, etc., which is the basis for achieving the synergistic effect of ice nucleoprotein and AgI in subsequent steps).

[0020] As a preferred embodiment of the present invention, the solvent includes a phosphate buffer solution, wherein the pH of the phosphate buffer solution is 7.5-8.0.

[0021] As a preferred technical solution of the present invention, the droplet addition in step (2) is carried out under the conditions of avoiding light, 0-4℃ and stirring.

[0022] As a preferred embodiment of the present invention, the molar ratio of silver nitrate to ice nucleoprotein is 10-50:1, for example, 10:1, 20:1, 30:1, 40:1, 50:1, etc.

[0023] The purpose of step (2) is to make silver ions (Ag) + This specific binding to the active functional groups of ice nucleoproteins creates conditions for in-situ AgI generation on the ice nucleoprotein template. The principle lies in the negatively charged functional groups on the surface of ice nucleoproteins (primarily carboxylate-COO groups). - ) for Ag + The process involves electrostatic adsorption and coordination. This can be understood using the Langmuir adsorption model, which assumes that the surface of the ice nucleoprotein has a series of uniform, equivalent adsorption sites; each site can only adsorb one Ag. + Ions form a monolayer; there is no interaction between adsorption sites.

[0024] Under this model, the amount of adsorption on the protein surface at adsorption equilibrium is... With Ag in solution + equilibrium concentration C The relationship is:

[0025] in, This represents the theoretical maximum adsorption capacity, corresponding to the amount of adsorption when all active sites are occupied. K ads It is the adsorption equilibrium constant, reflecting Ag + Affinity to the binding site of ice nucleoproteins, K ads The higher the value, the easier the adsorption process.

[0026] This invention achieves instantaneous Ag in the system by controlling the molar ratio of silver nitrate to ice nucleoprotein and by slow dropwise addition. + concentration C Maintaining a low level, thereby driving Ag + It preferentially and orderly occupies effective adsorption sites on the protein surface, making the total dosage approach the optimal level. This move aims to achieve Ag + High-density, selective immobilization at protein active sites forms ice nucleoprotein-Ag for subsequent in situ reactions. + Precursor, and minimize free Ag + .

[0027] As a preferred embodiment of the present invention, the molar ratio of iodide ions in the water-soluble metal iodide to silver ions in the silver nitrate is 1-1.05:1, for example, 1:1, 1.01:1, 1.02:1, 1.03:1, 1.04:1, 1.05:1, etc.

[0028] This invention controls the molar ratio of iodide ions in water-soluble metal iodides to silver ions in silver nitrate within the above-mentioned range, so that all silver ions bound to the surface of ice nucleoprotein are converted into AgI.

[0029] Because in step (2) Ag + It has been pre-fixed onto the ice nucleoprotein molecular chain, I - The introduction of AgI allows AgI nuclei to directly nucleate and grow around the active sites of proteins, ultimately forming nano-AgI particles with an average size of 10-50 nm. This "in-situ precipitation" strategy ensures that the nano-AgI particles achieve close contact with the active sites of ice nuclei proteins at the atomic / molecular level. This structure allows the pre-organized water molecule clusters of ice nuclei proteins at higher temperatures to be immediately guided into ice crystals by neighboring, highly lattice-matched AgI particles, thus achieving a rapid relay from "pre-organization" to "lattice guidance." This results in composite ice nuclei materials with excellent properties such as high nucleation threshold temperature (above -4℃) and fast nucleation rate.

[0030] As a preferred technical solution of the present invention, the dripping in step (3) is carried out under the conditions of avoiding light, 0-4℃ and stirring.

[0031] As a preferred embodiment of the present invention, the water-soluble metal iodide is added dropwise to the ice nucleoprotein-Ag in the form of a solution. + In the precursor solution, the water-soluble metal iodide includes any one or more of potassium iodide, sodium iodide, lithium iodide, and ammonium iodide.

[0032] As a preferred embodiment of the present invention, the purification method is dialysis.

[0033] This invention removes unreacted ions and byproducts through dialysis to obtain purified composite ice core materials. Exemplarily, dialysis is performed using a dialysis bag with a molecular weight cutoff greater than that of the ice core protein at 4°C. The dialysis process follows Fick's diffusion law, and impurity ions (such as K+) are dispersed. + NO3 - Excessive I - Removal flux (etc.) J With the concentration gradient inside and outside the membrane Proportional:

[0034] In the formula, JFor diffusion flux, D The diffusion coefficient is... C ion The value represents the concentration of impurity ions, and x is the coordinate perpendicular to the dialysis membrane. By continuously replacing the external dialysis fluid (total time 48-72 hours), a high concentration gradient is maintained until conductivity testing shows that the ions have been completely removed, resulting in a pure dispersion of the composite ice core material.

[0035] As a preferred embodiment of the present invention, the purified material is further freeze-dried to obtain the composite ice core material.

[0036] For the purposes of facilitating storage, transportation and precise use, the present invention freeze-dries the purified composite ice core material dispersion.

[0037] As a preferred embodiment of the present invention, the freeze-drying method involves freezing at a temperature of -50°C or less for 3-10 hours, followed by freeze-drying at a temperature of -50°C or less and a vacuum of less than 10 Pa for 12-48 hours.

[0038] The freeze-drying method provided by this invention can avoid the destruction of ice nucleus protein activity and nanostructure by high temperature, and finally obtain a loose composite ice nucleus material powder.

[0039] Thirdly, the present invention provides the application of composite ice core materials as described in the first aspect or composite ice core materials prepared by the preparation method described in the second aspect in freezing rain intervention.

[0040] The technical solution provided by the embodiments of the present invention has the following advantages compared with the prior art: (1) The composite ice core material provided by the present invention has excellent properties such as high nucleation threshold temperature (above -4℃) and fast nucleation rate, and can exhibit excellent intervention effect in the core temperature zone of freezing rain intervention, thereby effectively reducing the occurrence of freezing rain disasters.

[0041] (2) The preparation method provided by the present invention achieves efficient composite of two phases at the nanoscale by guiding in situ synthesis of silver iodide nanoparticles on the surface of ice nuclei protein, generating a quantitatively verifiable nucleation synergistic effect, effectively improving the nucleation threshold temperature and nucleation rate of composite ice nuclei material, and breaking through the performance limitations of simple physical mixing. Detailed Implementation

[0042] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0043] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0044] Example 1 This embodiment provides a composite ice core material and its preparation method, the preparation method comprising the following steps: (1) Take the frozen ice nucleoprotein (INP, extracted from Snomax powder) stock solution and thaw it at 4°C. Dilute it with pre-cooled PBS buffer (pH 8) to prepare a solution with the following concentration: C INP 50 mL of a 2.0 mg / mL ice nucleoprotein solution was kept in an ice bath throughout the process.

[0045] (2) Transfer the above ice nucleoprotein solution to a light-protected reaction flask and place it on a low-temperature stirring table at 4°C. Using a syringe pump, add 7.35 mL of 0.1 M AgNO3 solution dropwise at a rate of 0.2 mL / min. The calculated molar ratio of silver ions to ice nucleoprotein is 30:1. After the addition is complete, continue stirring in the dark for 30 minutes to obtain ice nucleoprotein-Ag. + Precursor solution.

[0046] (3) Maintain light-proof and low-temperature conditions, and inject the ice nucleoprotein-Ag obtained in step (2) at a rate of 0.2 mL / min. + 7.50 mL of 0.1 M KI solution was added dropwise to the precursor solution to make the molar ratio of iodide ions to silver ions 1.02. The solution was immediately observed to change from colorless to pale yellow and gradually deepen in color. The reaction was continued to be stirred for 2 hours to obtain the reaction solution.

[0047] (4) Transfer the reaction solution obtained in step (3) to a dialysis bag with a molecular weight cutoff of 10 kDa, and place the dialysis bag in a container containing 2 L of ultrapure water. Dialyze and purify the solution at 4°C. Replace the ultrapure water (i.e., the dialysis fluid) in the container every 6 hours for a total of 48 hours. Detect the conductivity of the final dialysis fluid until it is less than 5 μS / cm, at which point the dialysis is complete. Dispense the purified pale yellow colloidal dispersion into freeze-drying bottles, pre-freeze at -80°C for 6 hours, and then transfer it to a freeze dryer. Freeze-dry the solution at a condenser temperature of -85°C and a vacuum degree of <10 Pa for 24 hours to obtain a light yellow, fluffy composite ice core material powder.

[0048] Example 2 This embodiment provides a composite ice core material and its preparation method. The preparation method is the same as that in Example 1. The difference between Example 1 and Example 1 is that the molar ratio of silver ions to ice core protein in step (2) of this embodiment is 10:1.

[0049] Example 3 This embodiment provides a composite ice core material and its preparation method. The preparation method is the same as that in Example 1. The difference between Example 1 and Example 1 is that the molar ratio of silver ions to ice core protein in step (2) of this embodiment is 50:1.

[0050] Performance testing DSC tests were performed on the ice core material provided in the examples.

[0051] (1) Weigh the following three samples in equal mass (2.0 mg): (A) the composite ice core material powder prepared in Example 1, (B) pure ice core protein (Snomax) powder, and (C) pure nano silver iodide (AgI) powder; mix them with 10.0 μL of ultrapure water in a special aluminum crucible for differential scanning calorimetry and seal them.

[0052] (2) The sample crucibles were placed in the DSC instrument and cooled from 5.0℃ to -30.0℃ at a constant cooling rate (2.0℃ / min) under nitrogen protection to obtain the heat flow curve as a function of temperature. The crystallization (freezing) process of water releases latent heat, which is represented by an exothermic peak on the curve.

[0053] (3) Observation indicators and verification conclusions 1) Observation indicators Nucleation initiation temperature ( T onset The nucleation temperature (t) is the temperature at which the exothermic peak begins to deviate significantly from the baseline. This temperature directly reflects the ease with which the material triggers ice crystal formation; a higher value indicates a higher nucleation activity temperature.

[0054] Peak shape characteristics: The sharpness of the exothermic peak can usually be expressed as the half-width at half-maximum (ΔT). FWHM Quantitative characterization. The sharper the peak shape (ΔT)... FWHM The smaller the value, the more concentrated and synchronous the nucleation events are, meaning the faster the nucleation rate.

[0055] 2) Verification conclusions If the DSC curve of sample (A) satisfies both of the following conditions, then the synergistic effect is proven: Condition 1: Its nucleation initiation temperature is significantly higher than that of the pure AgI sample (C).

[0056] Condition 2: Its nucleation initiation temperature is close to or even slightly higher than that of the pure ice nucleoprotein sample (B), and its exothermic peak shape is sharper than that of sample (B).

[0057] (4) Test results The DSC test results are shown in Table 1: Table 1

[0058] Table 1 shows that the T of sample A onset It was 4.4°C higher than pure AgI (sample C); and compared with pure ice nucleoprotein (sample B), its T... onset Higher and ΔT FWHM With a narrowing of approximately 42%, it fully meets the synergistic effect criterion, indicating that the composite ice core material obtained by the "in-situ synthesis method" of this invention can rapidly induce crystallization at -2.8°C, which can meet the needs of artificial intervention in the near-surface cold layer under freezing rain conditions.

[0059] This indicates that the composite ice core material of this invention not only inherits the high threshold temperature characteristics of ice core proteins, but also significantly accelerates the nucleation kinetics process by introducing in-situ synthesized nano-AgI, achieving a synergistic effect of "1+1>2". Furthermore, this invention provides a standard verification method based on differential scanning calorimetry, ensuring objective and reliable performance evaluation and demonstrating clear prospects for engineering applications.

[0060] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0061] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those 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 invention. Therefore, the present invention is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A composite ice core material, characterized in that, The composite ice core material includes ice core protein and silver nanoparticles of iodide complexed on the surface of the ice core protein.

2. The composite ice core material according to claim 1, characterized in that, The molar ratio of silver iodide to ice nucleus protein in the composite ice nucleus material is 10-50:1; And / or, the average particle size of the nano-silver iodide particles is 10-50 nm.

3. The composite ice core material according to claim 1 or 2, characterized in that, The ice nucleoprotein is selected from any one or more of bacterial ice nucleoproteins, fungal ice nucleoproteins, or recombinant ice nucleoproteins; Preferably, the ice nucleoprotein is derived from *Pseudomonas syringae*, *Pseudomonas fluorescens*, *Erwinia gracilis*, or *Xanthomonas campestris*. More preferably, the ice nucleoprotein exists in the form of purified protein, bacterial extract, or inactivated bacterial powder.

4. A method for preparing a composite ice core material as described in any one of claims 1-3, characterized in that, The preparation method includes the following steps: (1) Dissolve the ice nucleoprotein in a solvent to obtain an ice nucleoprotein solution; (2) Silver nitrate was added dropwise to the ice nucleoprotein solution to obtain ice nucleoprotein-Ag. + Precursor solution; (3) Add water-soluble metal iodide dropwise to the ice nucleoprotein-Ag + The precursor solution was purified to obtain the composite ice core material.

5. The preparation method according to claim 4, characterized in that, The operation of step (1) is carried out at 0-4℃; And / or, the concentration of the ice nucleoprotein solution is 1.0-5.0 mg / mL; And / or, the solvent includes a phosphate buffer having a pH of 7.5-8.

0.

6. The preparation method according to claim 4 or 5, characterized in that, The addition in step (2) is carried out under conditions of light protection, 0-4℃, and stirring. And / or, the molar ratio of silver nitrate to ice nucleoprotein is 10-50:

1.

7. The preparation method according to any one of claims 4-6, characterized in that, The molar ratio of iodide ions in the water-soluble metal iodide to silver ions in the silver nitrate is 1-1.05:

1.

8. The preparation method according to any one of claims 4-7, characterized in that, The addition described in step (3) is carried out under conditions of light protection, 0-4℃, and stirring. And / or, the water-soluble metal iodide includes any one or more of potassium iodide, sodium iodide, lithium iodide, and ammonium iodide.

9. The preparation method according to any one of claims 4-8, characterized in that, The purification method is dialysis; And / or, the purified material is further freeze-dried to obtain the composite ice core material.

10. The application of the composite ice core material as described in any one of claims 1-3 or the composite ice core material prepared by the preparation method as described in any one of claims 4-9 in freezing rain intervention.

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