CN117800458A - Clay mineral-based aggregate material and preparation method and application thereof - Google Patents

Abstract

The invention provides a clay mineral-based aggregate material, a preparation method and application thereof. The clay mineral-based aggregate material is a suspension with ssDNA enrichment capability, and comprises a negatively charged clay mineral nano-sheet, adenine nucleoside triphosphate, oligomeric lysine and water. The material combines the unique advantages of inorganic clay mineral and organic aggregate material in adsorption performance for the first time, takes part in two ways of promoting the increase of the aggregate quantity and improving the distribution coefficient of single aggregate to ssDNA through taking the negatively charged clay mineral nano-sheet layer as an anion component, obviously improves the enrichment efficiency of ssDNA, and has obviously higher enrichment efficiency to longer-chain ssDNA.

Description

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

Technical field

The 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 technique

Water pollution is an increasingly serious global environmental problem, which has a huge impact on human life and ecosystems. In aquatic ecological restoration, biodiversity is the key to maintaining ecosystem stability and function. Aquatic life is an important indicator for evaluating the water environment. Due to the uneven distribution of plankton in the water, the analysis of free DNA in the water body during water environment monitoring is an indispensable key link to characterize the health of the aquatic ecosystem. However, since the concentration of free DNA in water is very low, it is urgent to find a DNA enrichment material to enrich free DNA in water.

Coacervate droplets are generated by the liquid-liquid phase separation process between oppositely charged polymers or highly charged small molecules. Due to the characteristics of 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 inclined to form coacervate droplets, while rigid double-stranded DNA (dsDNA) and polylysine are more inclined to form gel-like aggregates, and 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 of forming coacervates with cationic components.

Therefore, how to improve the enrichment of DNA in aqueous solutions is an urgent problem that scientific researchers need to solve.

Contents of the invention

The object of the present invention is to provide a clay mineral-based aggregate material and its preparation method and application in view of the above-mentioned shortcomings of the prior art.

In order to achieve the above objects, the present invention adopts the following technical solutions:

The first object of the present invention is to provide a clay mineral-based aggregate material. The clay mineral-based aggregate material is a suspension with ssDNA enrichment ability, which includes negatively charged clay mineral nanosheets, adenine nucleosides Triphosphate, oligolysine and water, the concentration ratio of the adenine nucleoside triphosphate and the oligolysine is 1: (4-8).

Further, the clay mineral is a layered clay mineral, including any one of montmorillonite, illite and kaolinite.

Further, the negatively charged clay mineral nanosheets are obtained by peeling and separating the layered clay minerals. The average size of the clay mineral nanosheets is 150nm-300nm, and the negatively charged clay mineral nanosheets are The concentration is 0.02-0.08mg/mL.

Further, the aggregates contained in the clay mineral-based aggregate material have a spherical-like structure, and the number of aggregates per 10 μL is not less than 3.9×10 ⁵ .

The 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:

S1. Disperse the negatively charged clay mineral nanosheets in deionized water to form a suspension for later use;

S2. Prepare adenine nucleoside triphosphate aqueous solution and oligolysine aqueous solution, and then add adenine nucleoside triphosphate aqueous solution and oligolysine aqueous solution respectively to the suspension obtained in step S1 to obtain clay minerals. Based agglomerate material.

Further, in step S1, the preparation method of the negatively charged clay mineral nanosheets includes the following steps:

S11. After mixing and grinding a certain amount of clay minerals and NaNO ₃ evenly, the ground product is calcined at a certain temperature to obtain a calcined product;

S12, uniformly dispersing the calcined product in deionized water for ultrasonic dispersion, washing by centrifugation for multiple times, taking the last supernatant for freeze-drying and grinding to obtain a freeze-dried product, that is, a clay mineral nanosheet.

Further, the mass ratio of the clay mineral and NaNO ₃ is (0.5-3): (2.5-15); the calcination temperature is 300~450°C, the calcination time is 2~6h; the centrifugal speed is 8000r/min～10000r/min, wash 5～6 times, centrifuge time 5min～25min.

Further, the pH of the solution used in the preparation method is adjusted to 6.0-6.5.

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

Further, the time for the clay mineral-based aggregate material to enrich ssDNA is 2 to 10 minutes.

The fourth object of the present invention is to provide an ssDNA enrichment system, which includes the above-mentioned clay mineral-based aggregate material.

Compared with the prior art, the beneficial effects of the present invention are:

(1) A clay mineral-based condensate material provided by the invention is a suspension with ssDNA enrichment ability, including negatively charged clay mineral nanosheets, adenine nucleoside triphosphate, oligolysine and water . This material is the first to combine the unique advantages of inorganic clay minerals and organic condensate materials in adsorption performance. The negatively charged clay mineral nanosheets serve as anionic components to promote the increase in the number of condensates and improve the distribution coefficient of a single condensate to ssDNA. These two pathways significantly improve the enrichment efficiency of ssDNA, and the enrichment efficiency of longer ssDNA is significantly higher.

(2) The preparation method of clay mineral-based aggregate materials provided by the present invention has the advantages of simple steps, mild reaction conditions, and high environmental safety.

Description of drawings

FIG1 is a schematic diagram of the formation of the oligolysine/adenosine triphosphate aggregate and a clay mineral-based aggregate material of the present invention;

Figure 2 is the X-ray diffraction pattern before and after MMT-Na treatment in Example 2;

Figure 3a is a turbidity diagram of oligolysine/adenine nucleoside triphosphate aggregate suspension prepared with different molar ratios of K10/ATP;

Figure 3b shows the turbidity diagram of clay mineral-based oligolysine/adenine nucleoside triphosphate aggregate suspension prepared with different concentrations of MMT-Na;

Figure 4a is a microscope image of the prepared oligolysine/adenine nucleoside triphosphate condensate, the scale bar is 10 μm;

Figure 4b is a microscope image of the prepared clay mineral-based aggregates, the scale bar is 10 μm;

Figure 5a is a two-dimensional (2D) scatter plot of flow side scattered (SSC) and forward scattered (FSC) light of the prepared oligolysine/adenine nucleoside triphosphate aggregate suspension;

Figure 5b is a two-dimensional (2D) scatter plot of flow side scattered (SSC) and forward scattered (FSC) light prepared from a clay mineral-based aggregate suspension;

Figure 5c is a flow counting statistical diagram of oligolysine/adenine nucleoside triphosphate aggregate suspension and clay mineral-based aggregate suspension;

Figure 6a is a scanning electron microscope image of the oligolysine/adenine nucleoside triphosphate aggregate suspension after freeze-drying;

Figure 6b is a scanning electron microscope image of the clay mineral-based aggregate suspension after freeze-drying;

FIG7 is a Zeta potential diagram of MMT-Na suspension, oligolysine/adenosine triphosphate aggregate suspension, and clay mineral-based aggregate suspension;

Figure 8 is a confocal fluorescence photo of TAMRA-ssDNA (A10) enriched in oligolysine/adenine nucleoside triphosphate condensates;

Figure 9 is a confocal fluorescence photo of TAMRA-ssDNA (A30) enriched in oligolysine/adenine nucleoside triphosphate condensates;

Figure 10 is a K value statistical diagram of TAMRA-ssDNA (A10, A30) with different monomer lengths enriched by oligolysine/adenine nucleoside triphosphate condensates;

Figure 11 is a confocal fluorescence photo of TAMRA-ssDNA (A10) enriched in clay mineral-based aggregates;

Figure 12 is a confocal fluorescence photo of TAMRA-ssDNA (A30) enriched in clay mineral-based aggregates;

Figure 13 is a statistical diagram of the K value of TAMRA-ssDNA (A10, A30) with different monomer lengths enriched in clay mineral-based condensates;

Figure 14 is a statistical histogram of the partition coefficient K value of TARMA-ssDNA enriched in oligolysine/adenine nucleoside triphosphate condensate and clay mineral-based condensate.

Detailed ways

In order to make the purpose, technical scheme and advantages of the present invention clearer, embodiments of the present invention are described in detail below, and 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 with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

Refer to Figure 1, which is a schematic diagram of the formation structure of the clay mineral-based condensate material of the present invention. The electrostatic interaction between the positively charged oligolysine and the negatively charged adenine nucleoside triphosphate results in a higher distribution of ssDNA. Coefficient of agglomerates, negatively charged clay mineral nanosheets as anionic components participate in promoting the formation of agglomerates, significantly improving the enrichment of ssDNA by increasing the number of agglomerates.

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

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

Example 1

This example prepares suspensions of oligolysine/adenine triphosphate aggregates with different molar ratios.

ATP was dissolved in deionized water to prepare a 100mmol/L ATP aqueous solution; oligolysine was dissolved in deionized water to prepare a 100mmol/L K10 aqueous solution; 4μL ATP aqueous solution and different volumes (16μL, 20μL, 24μL, 28μL, 32μL, 36μL, 40μL) of K10 aqueous solution were added to deionized water in sequence and mixed evenly, with a total volume of 100μL to obtain an oligolysine/adenosine triphosphate coacervate suspension. The absorbance at a wavelength of 500nm was used to characterize the turbidity of the coacervate, and the detection index was set as "T".

Refer to Figure 3a, which shows the turbidity diagram of the oligolysine/adenine nucleoside triphosphate aggregate suspension prepared with different molar ratios of K10/ATP. It can be seen from the figure that the molar ratio of K10 to ATP is 5:1, 6 When :1, 7:1, and 8:1, the turbidity is high, and obvious white turbidity appears, indicating that a larger number of aggregates are formed at this time.

Referring to Figure 4a, it is an optical microscope image of the prepared oligolysine/adenine nucleoside triphosphate condensate. It can be seen from the figure that its average particle size is 3.1 μm.

Referring to Figure 5a, it is the flow side scattered (SSC) and forward scattered (FSC) light of the fluorescein isothiocyanate (FITC) labeled oligolysine/adenine nucleoside triphosphate condensate suspension. Three-dimensional (2D) scatter plot, the number of aggregates with a sample volume of 10 μL is 2.9×10 ⁵ .

Refer to Figure 6a, which is a scanning electron microscope image of the oligolysine/adenine nucleoside triphosphate condensate suspension after freeze-drying. It can be seen from the figure that its surface is smooth and uniform, with a spherical-like structure.

Example 2

In this embodiment, clay mineral-based aggregate materials are prepared.

After mixing and grinding a certain amount of montmorillonite MMT (3g) and NaNO ₃ (15g) evenly, the ground product was calcined at 350°C for 4 hours. The calcined product was added to deionized water for 12 hours, dispersed ultrasonically, and centrifuged at 9000 r/min for 5 times, with each centrifugation time being 5 min, 10 min, 15 min, 20 min, and 25 min. Take the supernatant of the last centrifugation and freeze-dry and grind it to obtain a freeze-dried product, which is clay mineral nanosheets, recorded as MMT-Na. Then a certain amount of MMT-Na is evenly dispersed in deionized water and stirred to form 0.1mg/ mL of MMT-Na stable suspension for later use; dissolve ATP into deionized water to prepare a 100mmol/L ATP aqueous solution; dissolve oligolysine into deionized water to prepare a 100mmol/L K10 aqueous solution; 4 μL ATP aqueous solution Add 32 μL of LK10 aqueous solution to the 0.1 mg/mL MMT-Na stable suspension and mix evenly. The total volume of the system is 100 μL to obtain a clay mineral-based aggregate material.

The solutions prepared in the above preparation process are all adjusted to pH 6.5 with hydrochloric acid and sodium hydroxide. The applicant found in the research process that when the pH of the solution is adjusted to 7-10, it is difficult to form agglomerates.

According to visual inspection, the clay mineral-based aggregate material prepared according to the above method is a suspension.

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

Refer to Figure 2, which shows the X-ray diffraction pattern of the 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 peeling off of MMT.

Referring to Figure 3b, it is a turbidity diagram of the clay mineral-based coagulant 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 coagulants at these concentrations.

Example 3

In this embodiment, clay mineral-based aggregate materials are prepared.

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

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

Example 4

In this embodiment, clay mineral-based aggregate materials are prepared.

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

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

Example 5

In this embodiment, clay mineral-based aggregate materials are prepared.

It is basically the same as Example 2, except that the mass ratio of MMT and NaNO ₃ is 2:10, the calcination temperature is 300°C, and the calcination time is 6 hours.

Example 6

This example prepares a clay mineral-based aggregate material.

It is basically the same as Example 2, except that the mass ratio of MMT and NaNO ₃ is 0.5:2.5, the calcination temperature is 450°C, and the calcination time is 2h.

Example 7

In this embodiment, clay mineral-based aggregate materials are prepared.

Basically the same as Example 2, except that the solution prepared during the preparation process was adjusted to pH 6.0 with hydrochloric acid and sodium hydroxide; 4 μL ATP aqueous solution and 32 μL K10 aqueous solution were sequentially added to 0.03 mg/mL MMT-Na to stabilize Mix evenly in the suspension, and the total volume of the system is 100 μL.

Example 8

This example prepares a clay mineral-based aggregate material.

Basically the same as Example 2, except that the solution prepared during the preparation process was adjusted to pH 6.3 with hydrochloric acid and sodium hydroxide; 4 μL ATP aqueous solution and 32 μL K10 aqueous solution were sequentially added to 0.13 mg/mL MMT-Na to stabilize Mix evenly in the suspension, and the total volume of the system is 100 μL.

In order to better explain the enrichment properties of the clay mineral-based aggregate materials prepared by the present invention, the applicant conducted the following research:

Performance characterization:

The clay mineral-based aggregate material was characterized by optical microscopy, and Examples 2-8 all had similar morphologies. Taking Example 2 as an example, referring to Figure 4b, it can be seen from the figure that the average particle size is 3.5 μm, which is larger than that of oligolysine/adenine nucleoside triphosphate condensate to a certain extent.

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

Referring to Figure 5c, there are flow cytometry statistical diagrams of oligolysine/adenine nucleoside triphosphate condensate suspension and clay mineral-based condensate suspension. These data show that with oligolysine/adenine nucleoside Compared with glycoside triphosphate aggregates (Figure 4a, Figure 5a), the number of clay mineral-based aggregates has significantly increased, further confirming the promotion effect of MMT-Na on the formation of aggregates.

Referring to FIG6 b , it is a scanning electron microscope image of the freeze-dried clay mineral-based aggregate suspension, the surface of which is smooth and uniform, presenting a spherical structure.

Referring to Figure 7, the Zeta potential of the MMT-Na suspension is -17.73 mV, the oligolysine/adenosine triphosphate aggregate suspension is 39.77 mV, and the Zeta potential of the MMT-Na-based oligolysine/adenosine triphosphate aggregate suspension is 39.37 mV. The potentials of the latter two remain basically unchanged, indicating that MMT-Na enters the aggregate as a component, thereby promoting the formation of MMT-Na-based oligolysine/adenosine triphosphate aggregates.

In order to better explain the effect of the clay mineral-based aggregate of the present invention on the enrichment of ssDNA in water, the applicant conducted the following research:

Example 9

The oligolysine/adenine nucleoside triphosphate condensate prepared in Example 1 was used to enrich the ssDNA in the solution.

The selected molar ratio of K10 to ATP is 8:1; the selected ssDNA is A10 and A30 with different chain lengths. A10 is DNA composed of 10 monomers (adenine nucleotides); A30 is composed of 30 monomers (Adenine nucleotide) DNA; purchased from Sangon Bioengineering (Shanghai) Co., Ltd.

In order to facilitate characterization and detection, ssDNA was fluorescently labeled. In this example, the fluorescent marker selected was TAMRA (carboxytetramethylrhodamine). FAM (carboxyfluorescein), Cy3, Cy5 (cyanine) can also be used. dye), etc. for labeling.

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

To the prepared oligolysine/adenine nucleoside triphosphate condensate, add 0.5 μL of 100 μmol/L TAMRA-ssDNA aqueous solution (A10, A30), let it stand for 5 minutes, and then remove 5 μL of the aggregate suspension. Add it to the hydrophobically modified glass slide sample pool, and then use a confocal fluorescence microscope to take pictures at an excitation wavelength of 561 nm and an emission wavelength range of 575 to 700 nm. The dye is mainly concentrated in the condensed phase. The photos were analyzed and processed using the software Image J. The enrichment efficiency was determined by the partition coefficient (K, the ratio of the fluorescence intensity inside the aggregate and the surrounding dilute aqueous phase). Measure 12 different condensate droplets under the same field of view, calculate the average value and standard deviation, and then obtain the enrichment efficiency of the condensate for TAMRA-ssDNA of different monomer lengths.

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

Refer to Figures 8, 9 and 10, which are respectively confocal fluorescence photos and K value statistical charts of oligolysine/adenine nucleoside triphosphate condensates enriched with TAMRA-ssDNA (A10, A30) of different monomer lengths. , it can be seen from the figure: when the TAMRA-ssDNA concentration is 0.5 μmol/L, the distribution coefficients of A10 and A30 are 29.67 and 62.23 respectively.

Example 10

The clay mineral-based coacervate prepared in Example 2 was used to enrich ssDNA in the solution.

Basically the same as Example 9.

Example 11

The clay mineral-based aggregate prepared in Example 3 was used to enrich the ssDNA in the solution.

Basically the same as Example 9.

Example 12

The clay mineral-based aggregate prepared in Example 4 was used to enrich the ssDNA in the solution.

Basically the same as Example 9.

Example 13

The clay mineral-based aggregate prepared in Example 5 was used to enrich the ssDNA in the solution.

Basically the same as Example 9.

Example 14

The clay mineral-based aggregate prepared in Example 6 was used to enrich the ssDNA in the solution.

Basically the same as Example 9.

Embodiment 15

The clay mineral-based aggregate prepared in Example 7 was used to enrich ssDNA in the solution.

Basically the same as Example 9.

Example 16

The clay mineral-based coacervate prepared in Example 8 was used to enrich ssDNA in the solution.

Basically the same as Example 9.

The results of Examples 10-16 show that the clay mineral-based aggregates prepared in Examples 2-8 respectively show similar enrichment effects on ssDNA of different monomer lengths. Example 10 is taken as an example below. Explain in detail.

Referring to Figure 11, Figure 12 and Figure 13, the confocal fluorescence photos and K value statistical diagrams of TAMRA-ssDNA (A10, A30) of different monomer lengths enriched in clay mineral-based condensates are shown in the figure: the concentration of TAMRA-ssDNA is At 0.5 μmol/L, the distribution coefficients of A10 and A30 are 50.07 and 114.32 respectively.

Referring to FIG. 14 , in the clay mineral-based aggregates, the distribution coefficient of A10 increased from 29.67 to 50.07; and the distribution coefficient of A30 increased from 62.23 to 114.32.

In summary, compared with oligolysine/adenine nucleoside triphosphate condensates, clay mineral-based condensates can increase the number of condensates and improve the distribution coefficient of a single condensate to ssDNA. , which increases the enrichment efficiency of ssDNA by nearly two times, and the enrichment efficiency of longer ssDNA is significantly higher.

Things not covered above are applicable to the existing technology.

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 will Various modifications, additions, or similar substitutions may be made to the described specific embodiments without departing from the direction of the present invention or exceeding the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc. made to the above embodiments based on the technical essence of the present invention shall be included in the protection scope of the present invention.

Claims (10)

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

2. The clay mineral-based agglomerate 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 agglomerate material according to claim 2, wherein said negatively charged clay mineral nanoplatelets are obtained by flaking said layered clay mineral, said clay mineral nanoplatelets having an average lateral dimension of 150nm to 300nm and a concentration of 0.02 to 0.08mg/mL.

4. The clay mineral-based agglomerate material according to claim 1, wherein the agglomerates contained in the clay mineral-based agglomerate material have a spheroid-like structure, and the number of agglomerates per 10 μl is not less than 3.9x10 ⁵ 。

5. A method for preparing a clay mineral-based agglomerate material according to any one of claims 1-4, comprising the steps of:

s1, dispersing a clay mineral nano sheet layer with negative electricity in deionized water to form a suspension for later use;

s2, preparing an adenine nucleoside triphosphate aqueous solution and an oligolysine aqueous solution, and then sequentially adding the adenine nucleoside triphosphate aqueous solution and the oligolysine aqueous solution into the suspension obtained in the step S1 respectively to obtain the clay mineral-based aggregate material.

6. The method according to claim 5, wherein in the step S1, the method for preparing the negatively charged clay mineral nanoplatelets comprises the steps of:

s11, mixing a certain amount of clay mineral and NaNO ₃ After mixing and grinding uniformly, calcining the grinding product at a certain temperature to obtain a calcined product;

s12, uniformly dispersing the calcined product into deionized water for ultrasonic dispersion, centrifugally washing for multiple times, and freeze-drying and grinding the supernatant fluid of the last time to obtain a freeze-dried product, thus obtaining the clay mineral nano-sheet layer.

7. The method of claim 6, wherein the clay mineral is mixed with NaNO ₃ The mass ratio of (2.5-15) is (0.5-3); the calcining temperature is 300-450 ℃ and the calcining time is 2-6 h; the rotational speed of the centrifugation is 8000 r/min-10000 r/min, the washing is carried out for 5-6 times, and the centrifugation time is 5-25 min.

8. The preparation method according to claim 6, wherein the pH of the solution used in the preparation method is adjusted to 6.0-6.5.

9. Use of the clay mineral-based agglomerate material of any one of claims 1-4 for ssDNA enrichment in a body of water, wherein the concentration of ssDNA in the body of water is no greater than 1 μmol/L.

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