A clay mineral-based aggregate material and its preparation method and application

Abstract

The present invention provides a clay mineral-based coacervate material, its preparation method, and application. The clay mineral-based coacervate material is a suspension capable of enriching ssDNA, comprising negatively charged clay mineral nanosheets, adenosine triphosphate, oligolysine, and water. This material, for the first time, combines the unique adsorption properties of inorganic clay minerals and organic coacervate materials. By using the negatively charged clay mineral nanosheets as anionic components to promote the increase in the number of coacervates and to increase the partition coefficient of individual coacervates for ssDNA, the ssDNA enrichment efficiency is significantly improved, and the enrichment efficiency for longer-chain ssDNA is significantly higher.

Description

Technical Field

[0001] The present invention belongs to the technical field of water environment monitoring, and in particular relates to a clay mineral-based aggregate material and a preparation method and application thereof. Background Art

[0002] Water pollution is an increasingly serious global environmental problem, significantly impacting human life and ecosystems. In aquatic ecological restoration, biodiversity is crucial for maintaining ecosystem stability and function. Aquatic organisms are important indicators for assessing the aquatic environment. Due to the uneven distribution of plankton in water, analyzing cell-free DNA in water is an essential component of water environment monitoring and a key component in characterizing the health of aquatic ecosystems. However, due to the extremely low concentration of cell-free DNA in water, finding a DNA enrichment material to enrich this free DNA in water is urgently needed.

[0003] Coacervate droplets are produced by the liquid-liquid phase separation process between oppositely charged polymers or highly charged small molecules. Due to their liquid-like fluidity and high isolation capacity, coacervate droplets provide a chemically enriched environment. These rich environments can ensure material exchange with the surrounding environment, high biomolecule loading and catalytic activity, making coacervate droplets have great application prospects in the field of material adsorption. Studies have reported that flexible single-stranded DNA (ssDNA) and polylysine are more likely to form coacervate droplets, while rigid double-stranded DNA (dsDNA) and polylysine are more likely to form gel-like aggregates. However, there are no reports on the formation of coacervates between oligolysine with smaller molecular weight and DNA. In addition, the concentration of free DNA in water is often extremely low, which is not enough to reach the concentration required to form coacervates with cationic components.

[0004] Therefore, how to improve the enrichment of DNA in aqueous solution is an urgent problem that scientific researchers need to solve. Summary of the Invention

[0005] The purpose of the present invention is to provide a clay mineral-based aggregate material and a preparation method and application thereof in response to the above-mentioned deficiencies in the prior art.

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

[0007] The first object of the present invention is to provide a clay mineral-based coacervate material, which is a suspension with ssDNA enrichment ability, comprising negatively charged clay mineral nanosheets, adenosine triphosphate, oligolysine and water, wherein the concentration ratio of the adenosine triphosphate to the oligolysine is 1:(4~8).

[0008] Furthermore, the clay mineral is a layered clay mineral, including any one of montmorillonite, illite and kaolinite.

[0009] Furthermore, the negatively charged clay mineral nanosheets are obtained by flaking and separating the layered clay mineral, the average size of the clay mineral nanosheets is 150 nm-300 nm, and the concentration of the negatively charged clay mineral nanosheets is 0.02-0.08 mg / mL.

[0010] Furthermore, the aggregates contained in the clay mineral-based aggregate material are spherical in structure, and the number of aggregates per 10 μL is not less than 3.9×10 5 .

[0011] A second object of the present invention is to provide a method for preparing the above-mentioned clay mineral-based aggregate material, comprising the following steps:

[0012] S1, dispersing negatively charged clay mineral nanosheets in deionized water to form a suspension for later use;

[0013] S2. Prepare an adenosine triphosphate aqueous solution and an oligolysine aqueous solution, and then add the adenosine triphosphate aqueous solution and the oligolysine aqueous solution to the suspension obtained in step S1, respectively, to obtain a clay mineral-based aggregate material.

[0014] Furthermore, in step S1, the method for preparing the negatively charged clay mineral nanosheet layer comprises the following steps:

[0015] S11, mixing a certain amount of clay mineral and NaNO3 and grinding them uniformly, and calcining the ground product at a certain temperature to obtain a calcined product;

[0016] S12. The calcined product is uniformly dispersed in deionized water and ultrasonically dispersed. The product is centrifuged and washed multiple times. The supernatant is taken out for the last step and freeze-dried and ground to obtain a freeze-dried product, namely, a clay mineral nanosheet.

[0017] Furthermore, the mass ratio of the clay mineral to NaNO3 is (0.5-3):(2.5-15); the calcination temperature is 300-450°C, and the calcination time is 2-6 hours; the centrifugal speed is 8000r / min-10000r / min, washing is performed 5-6 times, and the centrifugation time is 5min-25min.

[0018] Furthermore, the solutions used in the preparation method are adjusted to pH 6.0-6.5.

[0019] A third object of the present invention is to provide the use of the above-mentioned clay mineral-based aggregate material for enriching ssDNA in water, wherein the concentration of ssDNA in the water is not higher than 1 μmol / L.

[0020] Furthermore, the clay mineral-based aggregate material enriches ssDNA for 2 to 10 minutes.

[0021] A fourth object of the present invention is to provide an ssDNA enrichment system comprising the above-mentioned clay mineral-based aggregate material.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The present invention provides a clay mineral-based aggregate material, which is a suspension capable of ssDNA enrichment, comprising negatively charged clay mineral nanosheets, adenosine triphosphate, oligolysine, and water. This material, for the first time, combines the unique adsorption properties of inorganic clay minerals with those of organic aggregates. By using the negatively charged clay mineral nanosheets as anionic components to promote the increase in the number of aggregates and to increase the partition coefficient of individual aggregates for ssDNA, the material significantly improves the ssDNA enrichment efficiency, with significantly higher enrichment efficiency for longer-chain ssDNA.

[0024] (2) The method for preparing clay mineral-based aggregate materials provided by the present invention has the advantages of simple steps, mild reaction conditions, and high environmental safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the formation of the oligolysine / adenosine triphosphate aggregate and a clay mineral-based aggregate material of the present invention;

[0026] Figure 2 The X-ray diffraction patterns before and after MMT-Na treatment in Example 2;

[0027] Figure 3a Turbidity graphs of oligolysine / adenosine triphosphate aggregate suspensions prepared at different molar ratios of K10 / ATP;

[0028] Figure 3b Turbidity graphs of clay mineral-based oligolysine / adenosine triphosphate aggregate suspensions prepared with different concentrations of MMT-Na;

[0029] Figure 4a Microscope image of the prepared oligo-lysine / adenosine triphosphate aggregates, scale bar is 10 μm;

[0030] Figure 4b Microscope images of the prepared clay mineral-based aggregates, the scale bar is 10 μm;

[0031] Figure 5aTo prepare two-dimensional (2D) scatter plots of side scatter (SSC) and forward scatter (FSC) light of oligo-lysine / adenosine triphosphate aggregate suspension;

[0032] Figure 5b To prepare two-dimensional (2D) scatter plots of flow cytometry side scattered (SSC) and forward scattered (FSC) light of a clay mineral-based aggregate suspension;

[0033] Figure 5c Flow cytometric statistics of oligolysine / adenosine triphosphate aggregate suspension and clay mineral-based aggregate suspension;

[0034] Figure 6a This is a scanning electron micrograph of a freeze-dried oligolysine / adenosine triphosphate aggregate suspension;

[0035] Figure 6b This is a scanning electron micrograph of a freeze-dried suspension of clay mineral-based aggregates;

[0036] Figure 7 Zeta potential diagrams of MMT-Na suspension, oligolysine / adenosine triphosphate aggregate suspension, and clay mineral-based aggregate suspension;

[0037] Figure 8 This is a confocal fluorescence photograph of TAMRA-ssDNA (A10) enriched in oligo-lysine / adenosine triphosphate aggregates;

[0038] Figure 9 This is a confocal fluorescence photograph of TAMRA-ssDNA (A30) enriched in oligo-lysine / adenosine triphosphate aggregates;

[0039] Figure 10 The K value statistical diagram of the enrichment of TAMRA-ssDNA with different monomer lengths (A10, A30) by oligo-lysine / adenosine triphosphate aggregates;

[0040] Figure 11 This is a confocal fluorescence image of TAMRA-ssDNA (A10) enriched in clay mineral-based aggregates;

[0041] Figure 12 This is a confocal fluorescence image of TAMRA-ssDNA (A30) enriched in clay mineral-based aggregates;

[0042] Figure 13 The K value statistics of the enrichment of TAMRA-ssDNA with different monomer lengths (A10, A30) in clay mineral-based aggregates;

[0043] Figure 14Statistical bar graph of the distribution coefficient K value of TARMA-ssDNA enriched in oligolysine / adenosine triphosphate aggregates and clay mineral-based aggregates. DETAILED DESCRIPTION

[0044] To make the objectives, technical solutions, and advantages of the present invention more apparent, embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0045] refer to Figure 1 , is a schematic diagram of the formation structure of the clay mineral-based aggregate material of the present invention. The positively charged oligolysine and the negatively charged adenine triphosphate form aggregates with a high partition coefficient for ssDNA through electrostatic interaction. The negatively charged clay mineral nanosheets act as an anionic component to promote aggregate formation, significantly improving the enrichment of ssDNA by increasing the number of aggregates.

[0046] In some embodiments, the cationic component of the aggregates includes, but is not limited to, oligolysine, oligoarginine, polylysine, polyarginine, polydiallyldimethylammonium chloride (PDDA), and the like, and the anionic component includes, but is not limited to, ATP, for example, oligoaspartic acid, polyaspartic acid, DNA, RNA, and the like. The oligolysine mentioned in the present invention generally refers to an oligomer composed of 2 to 10 lysine residues. Oligomeric amino acids with less than 10 monomers are difficult to form aggregates.

[0047] The oligolysine selected in the specific embodiment is composed of 10 lysine residues, has a molecular weight of 1299.75 g / mol, and was purchased from Hefei Guopeptide Biotechnology Co., Ltd.

[0048] Example 1

[0049] In this example, oligolysine / adenosine triphosphate aggregate suspensions with different molar ratios were prepared.

[0050] ATP was dissolved in deionized water to prepare a 100 mmol / L ATP aqueous solution. Oligolysine was dissolved in deionized water to prepare a 100 mmol / L K10 aqueous solution. 4 μL of the ATP aqueous solution and different volumes of K10 aqueous solution (16 μL, 20 μL, 24 μL, 28 μL, 32 μL, 36 μL, and 40 μL) were sequentially added to deionized water and mixed thoroughly, resulting in a total volume of 100 μL. This yielded a suspension of oligolysine / adenosine triphosphate aggregates. The turbidity of the aggregates was measured using a microplate reader at a wavelength of 500 nm, with the detection index set as "T."

[0051] refer to Figure 3a , which is the turbidity diagram of the oligolysine / adenosine triphosphate aggregate suspension prepared with different molar ratios of K10 / ATP. It can be seen from the figure that when the molar ratio of K10 to ATP is 5:1, 6:1, 7:1, and 8:1, the turbidity is higher, and obvious white turbidity appears, indicating that a large number of aggregates are formed at this time.

[0052] refer to Figure 4a , which is an optical microscope image of the prepared oligolysine / adenosine triphosphate aggregates. As can be seen from the figure, the average particle size is 3.1 μm.

[0053] refer to Figure 5a , which is a two-dimensional (2D) scatter plot of side scatter (SSC) and forward scatter (FSC) light of a suspension of oligolysine / adenosine triphosphate aggregates labeled with fluorescein isothiocyanate (FITC). The number of aggregates in a sample volume of 10 μL is 2.9×10 5 .

[0054] refer to Figure 6a , is a scanning electron micrograph of the freeze-dried oligolysine / adenosine triphosphate aggregate suspension. As can be seen from the figure, its surface is smooth and uniform, presenting a spherical structure.

[0055] Example 2

[0056] This example prepares a clay mineral-based aggregate material.

[0057] A certain amount of montmorillonite (MMT) and NaNO3 (15g) were mixed and ground uniformly, and the ground product was calcined at 350°C for 4 hours. The calcined product was added to deionized water for 12 hours, ultrasonically dispersed, and centrifuged at 9000 rpm for five times, with each centrifugation time of 5 minutes, 10 minutes, 15 minutes, 20 minutes, and 25 minutes. The supernatant of the last centrifugation was freeze-dried and ground to obtain a freeze-dried product, namely the clay mineral nanosheet, denoted as MMT-Na. A certain amount of MMT-Na was then evenly dispersed in deionized water and stirred to form a 0.1 mg / mL MMT-Na stable suspension for later use. ATP was dissolved in deionized water to prepare a 100 mmol / L ATP aqueous solution. Oligolysine was dissolved in deionized water to prepare a 100 mmol / L K10 aqueous solution. 4 μL of the ATP aqueous solution and 32 μL of the K10 aqueous solution were sequentially added to the 0.1 mg / mL MMT-Na stable suspension and mixed evenly. The total volume of the system was 100 μL, thereby obtaining a clay mineral-based aggregate material.

[0058] The solutions prepared in the above preparation process were all adjusted to pH 6.5 with hydrochloric acid and sodium hydroxide. During the research process, the applicant found that it was difficult to form coacervates when the pH of the solution was adjusted to 7-10.

[0059] Visual observation shows that the clay mineral-based aggregate material prepared by the above method is a suspension.

[0060] The average lateral size of the clay mineral nanosheet MMT-Na prepared in this embodiment is about 200 nm.

[0061] refer to Figure 2 , which is the X-ray diffraction pattern of MMT-Na prepared in Example 2 before and after treatment. As can be seen from the figure: the dotted line indicates that after NaNO3 molten salt treatment, the (001) diffraction peak of MMT shifts to a higher 2θ position, confirming the exfoliation of MMT.

[0062] refer to Figure 3b , which is the turbidity diagram of the clay mineral-based coacervate suspension prepared with different concentrations of MMT-Na. As can be seen from the figure: the turbidity of MMT-Na is relatively high at concentrations of 0.02 mg / mL, 0.04 mg / mL, and 0.06 mg / mL, indicating that MMT-Na has a good promoting effect on the formation of coacervates at these concentrations.

[0063] Example 3

[0064] This example prepares a clay mineral-based aggregate material.

[0065] It is basically the same as Example 2, except that the clay mineral is kaolinite.

[0066] The average lateral size of the clay mineral nanosheet kaolinite-Na prepared in this example is about 150 nm.

[0067] Example 4

[0068] This example prepares a clay mineral-based aggregate material.

[0069] It is basically the same as Example 2, except that the clay mineral is illite.

[0070] The average lateral size of the clay mineral nanosheet illite-Na prepared in this embodiment is about 300 nm.

[0071] Example 5

[0072] This example prepares a clay mineral-based aggregate material.

[0073] The method is basically the same as Example 2, except that the mass ratio of MMT to NaNO3 is 2:10, the calcination temperature is 300°C, and the calcination time is 6 hours.

[0074] Example 6

[0075] This example prepares a clay mineral-based aggregate material.

[0076] The method is basically the same as Example 2, except that the mass ratio of MMT to NaNO3 is 0.5:2.5, the calcination temperature is 450°C, and the calcination time is 2h.

[0077] Example 7

[0078] This example prepares a clay mineral-based aggregate material.

[0079] The method is basically the same as Example 2, except that the pH of the solutions prepared during the preparation process is adjusted to 6.0 with hydrochloric acid and sodium hydroxide; 4 μL of ATP aqueous solution and 32 μL of K10 aqueous solution are sequentially added to the 0.03 mg / mL MMT-Na stable suspension and mixed evenly, with a total volume of 100 μL.

[0080] Example 8

[0081] This example prepares a clay mineral-based aggregate material.

[0082] The method is basically the same as Example 2, except that the pH of the solutions prepared during the preparation process is adjusted to 6.3 with hydrochloric acid and sodium hydroxide; 4 μL of ATP aqueous solution and 32 μL of K10 aqueous solution are sequentially added to the 0.13 mg / mL MMT-Na stable suspension and mixed evenly, with a total volume of 100 μL.

[0083] In order to better illustrate the enrichment performance of the clay mineral-based aggregate material prepared by the present invention, the applicant conducted the following research:

[0084] Performance characterization:

[0085] The clay mineral-based aggregate material was characterized by optical microscopy, and Examples 2-8 all had similar morphologies. Figure 4b As shown in the figure, the average particle size is 3.5 μm, which is larger to a certain extent compared with the oligolysine / adenosine triphosphate aggregates.

[0086] refer to Figure 5b , which is a two-dimensional (2D) scatter plot of side scatter (SSC) and forward scatter (FSC) light of a suspension of FITC-labeled clay mineral-based aggregates. The number of aggregates in a sample volume of 10 μL is 3.9×10 5 .

[0087] refer to Figure 5c, are flow cytometry statistics of oligo-lysine / adenosine triphosphate aggregate suspension and clay mineral-based aggregate suspension. These data show that compared with oligo-lysine / adenosine triphosphate aggregate ( Figure 4a 、 Figure 5a ), the number of clay mineral-based aggregates increased significantly compared with that of the control group, which further confirmed the promoting effect of MMT-Na on the formation of aggregates.

[0088] refer to Figure 6b , is a scanning electron microscope image of a freeze-dried clay mineral-based aggregate suspension, showing a smooth and uniform surface with a spherical structure.

[0089] refer to Figure 7 The Zeta potential of the MMT-Na suspension was -17.73 mV, that of the oligolysine / adenosine triphosphate aggregate suspension was 39.77 mV, and that of the MMT-Na-based oligolysine / adenosine triphosphate aggregate suspension was 39.37 mV. The potentials of the latter two remained basically unchanged, indicating that MMT-Na entered the aggregate as a component, thereby promoting the formation of MMT-Na-based oligolysine / adenosine triphosphate aggregates.

[0090] In order to better illustrate the effect of the clay mineral-based aggregates of the present invention on ssDNA enrichment in water, the applicant conducted the following research:

[0091] Example 9

[0092] The oligolysine / adenosine triphosphate aggregates prepared in Example 1 were used to enrich ssDNA in the solution.

[0093] The molar ratio of K10 to ATP was 8:1. The ssDNAs used were A10 and A30 of different chain lengths, A10 is a DNA composed of 10 monomers (adenine nucleotides); A30 is a DNA composed of 30 monomers (adenine nucleotides); and they were purchased from Sangon Biotech (Shanghai) Co., Ltd.

[0094] To facilitate characterization and detection, ssDNA was fluorescently labeled. In this embodiment, the fluorescent marker used was TAMRA (carboxytetramethylrhodamine). FAM (carboxyfluorescein), Cy3, Cy5 (cyanine dyes), etc. can also be used for labeling.

[0095] Treatment of hydrophobically modified coverslips (18×18mm): 1) Clean the glass bottle: anhydrous ethanol and water; 2) Add a coverslip and sonicate: anhydrous ethanol covers the coverslip for 30 minutes; 3) Sonicate the hydrophobic modifier solution (15mL toluene + 1mL hydrophobic agent (trimethyl[3-(2-methoxy)propyl]silane)): 30 minutes, soak overnight (minimum time); 4) Pour the modifier into the organic waste liquid bucket, add anhydrous ethanol and sonicate for 15 minutes; 5) Clip the coverslip and place it in a 10mL beaker; 6) Dry in a drying oven at 57°C (do not dry for too long, 15-30 minutes); 7) After drying, clip it into the modified coverslip box.

[0096] To the prepared oligolysine / adenosine triphosphate aggregates, 0.5 μL of a 100 μmol / L TAMRA-ssDNA aqueous solution (A10, A30) was added. After standing for 5 minutes, 5 μL of the aggregate suspension was pipetted and added to a hydrophobically modified glass slide sample cell. The samples were then photographed using a confocal fluorescence microscope with an excitation wavelength of 561 nm and an emission wavelength range of 575–700 nm. The dye was primarily concentrated in the aggregate phase. Images were analyzed and processed using Image J software. The enrichment efficiency was determined by the partition coefficient (K), the ratio of the fluorescence intensity within the aggregate to the surrounding dilute aqueous phase. Measurements were taken of 12 different aggregate droplets within the same field of view, and the mean and standard deviation were calculated to determine the enrichment efficiency of the aggregates for TAMRA-ssDNA of varying monomer lengths.

[0097] Partition coefficient K = [FssDNA] coacervate phase / [FssDNA] dilute phase (F is the fluorescence intensity).

[0098] refer to Figure 8 、 Figure 9 and Figure 10 , respectively, are confocal fluorescence photographs of oligolysine / adenosine triphosphate aggregates enriched with TAMRA-ssDNA of different monomer lengths (A10, A30) and K value statistical graphs. It can be seen from the figure that when the concentration of TAMRA-ssDNA is 0.5 μmol / L, the distribution coefficients of A10 and A30 are 29.67 and 62.23, respectively.

[0099] Example 10

[0100] The clay mineral-based aggregates prepared in Example 2 were used to enrich ssDNA in the solution.

[0101] Basically the same as Example 9.

[0102] Example 11

[0103] The clay mineral-based aggregates prepared in Example 3 were used to enrich ssDNA in the solution.

[0104] Basically the same as Example 9.

[0105] Example 12

[0106] The clay mineral-based aggregates prepared in Example 4 were used to enrich ssDNA in the solution.

[0107] Basically the same as Example 9.

[0108] Example 13

[0109] The clay mineral-based aggregates prepared in Example 5 were used to enrich ssDNA in the solution.

[0110] Basically the same as Example 9.

[0111] Example 14

[0112] The clay mineral-based aggregates prepared in Example 6 were used to enrich ssDNA in the solution.

[0113] Basically the same as Example 9.

[0114] Example 15

[0115] The clay mineral-based aggregates prepared in Example 7 were used to enrich ssDNA in the solution.

[0116] Basically the same as Example 9.

[0117] Example 16

[0118] The clay mineral-based aggregates prepared in Example 8 were used to enrich ssDNA in the solution.

[0119] Basically the same as Example 9.

[0120] The results of Examples 10-16 show that the clay mineral-based aggregates prepared in Examples 2-8 respectively exhibit similar enrichment effects on ssDNA of different monomer lengths, which will be described in detail below using Example 10 as an example.

[0121] refer to Figure 11 、 Figure 12 and Figure 13 The confocal fluorescence photographs and K value statistics of clay mineral-based aggregates enriched with TAMRA-ssDNA of different monomer lengths (A10, A30). As can be seen from the figure, when the TAMRA-ssDNA concentration is 0.5 μmol / L, the distribution coefficients of A10 and A30 are 50.07 and 114.32, respectively.

[0122] refer to Figure 14In clay mineral-based aggregates, the distribution coefficient of A10 increased from 29.67 to 50.07; the distribution coefficient of A30 increased from 62.23 to 114.32.

[0123] In summary, compared with oligolysine / adenosine triphosphate aggregates, clay mineral-based aggregates can nearly double the ssDNA enrichment efficiency by promoting the increase in the number of aggregates and improving the distribution coefficient of single aggregates to ssDNA, and the enrichment efficiency for longer-chain ssDNA is significantly higher.

[0124] Any matters not mentioned above shall be subject to the existing technology.

[0125] Although some specific embodiments of the present invention have been described in detail through examples, those skilled in the art should understand that the above examples are for illustration only and are not intended to limit the scope of the present invention. Those skilled in the art of the present invention may make various modifications or additions to the described specific embodiments or replace them in similar ways, but they will not deviate from the direction of the present invention or exceed the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent replacements, improvements, etc. made to the above embodiments based on the technical essence of the present invention should be included in the scope of protection of the present invention.

Claims

1. A clay mineral-based aggregate material, characterized in that: The clay mineral-based condensate material is a suspension with ssDNA enrichment capability, comprising negatively charged clay mineral nanosheets, adenosine triphosphate, oligolysine and water; the concentration ratio of the adenosine triphosphate to the oligolysine is 1:(4-8).

2. The clay mineral-based aggregate material according to claim 1, wherein: The clay mineral is a layered clay mineral, including any one of montmorillonite, illite and kaolinite.

3. The clay mineral-based aggregate material according to claim 2, wherein: The negatively charged clay mineral nanosheets are obtained by flaking and separating the layered clay mineral. The average lateral size of the clay mineral nanosheets is 150 nm to 300 nm, and the concentration of the negatively charged clay mineral nanosheets is 0.02 to 0.08 mg / mL.

4. The clay mineral-based aggregate material according to claim 1, wherein: The aggregates contained in the clay mineral-based aggregate material are spherical in structure, and the number of aggregates per 10 μL is not less than 3.9×10 5 .

5. A method for preparing a clay mineral-based aggregate material according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, dispersing negatively charged clay mineral nanosheets in deionized water to form a suspension for later use; S2. Prepare an adenosine triphosphate aqueous solution and an oligolysine aqueous solution, and then add the adenosine triphosphate aqueous solution and the oligolysine aqueous solution to the suspension obtained in step S1, respectively, to obtain a clay mineral-based aggregate material.

6. The preparation method according to claim 5, wherein In step S1, the method for preparing the negatively charged clay mineral nanosheet layer comprises the following steps: S11, mixing a certain amount of clay mineral and NaNO3 and grinding them uniformly, and calcining the ground product at a certain temperature to obtain a calcined product; S12, uniformly dispersing the calcined product in deionized water and ultrasonically dispersing the product, washing the product several times by centrifugation, and then freeze-drying and grinding the supernatant to obtain a freeze-dried product, namely, a clay mineral nanosheet.

7. The preparation method according to claim 6, wherein The mass ratio of the clay mineral to NaNO3 is (0.5-3):(2.5-15); the calcination temperature is 300-450°C, and the calcination time is 2-6 hours; the centrifugal speed is 8000r / min-10000r / min, washing is performed 5-6 times, and the centrifugation time is 5min-25min.

8. The preparation method according to claim 6, wherein The solutions used in the preparation method are all adjusted to pH 6.0-6.

5.

9. Use of the clay mineral-based aggregate material according to any one of claims 1 to 4 for enriching ssDNA in water, wherein the concentration of ssDNA in the water is not higher than 1 μmol / L.

10. A ssDNA enrichment system comprising the clay mineral-based aggregate material according to any one of claims 1 to 4.

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