A silver-silicon nanocomposite material, its preparation method and application

Abstract

The present invention discloses a silver-silicon nanocomposite material, its preparation method and application. The nanomaterial is prepared by the sol-gel method. The nanomaterial is spherical and quasi-spherical, and comprises the following steps: S1: Dissolve starch in water, adjust the pH value to 11 with sodium hydroxide, and add a silver nitrate solution during heating and stirring to obtain a silver nanosol; S2: Drop an ethanol solution containing water into tetraethyl orthosilicate, and then drop the obtained solution into the above silver nanosol. During this period, continuously stir, and finally add ammonia water to generate a precipitate. After washing, drying and grinding the reaction product into powder, it is ready. The nanocomposite particles prepared by the sol-gel method in the present invention have the advantages of simple operation, low cost, large yield, good material dispersibility, etc. The seed treatment technology of the present invention has simple operation, can shorten the average time for seed germination, improve the germination rate and vigor index of seeds, and increase the root length of seedlings.

Description

Technical Field

[0001] The present invention belongs to the technical field of plant cultivation, and specifically relates to a silver-silicon nanocomposite material, a preparation method thereof, and an application thereof. Background Art

[0002] Due to climate change, land drought has become more frequent, severe, and longer-lasting. Maize is one of the crops with the largest planting area worldwide and is an important food, feed, and cash crop in China, occupying an important position in China's agricultural production and national economy. Maize is a crop that is extremely vulnerable to drought. The germination time of seeds is prolonged under drought stress, and there are obvious inhibitory effects on germination rate, seedling establishment rate, vigor, etc. Therefore, improving the drought resistance of maize seeds during the germination period is crucial for maintaining their growth, development, yield, and quality.

[0003] Soaking seeds before sowing can lead to changes in the physiological state of seeds and enable seeds to germinate more effectively. In recent years, the use of nanotechnology for seed soaking treatment is an emerging field. Deyala et al. (2019) found that soaking maize seeds with nano-silica improved the germination rate and vigor index of seeds and enhanced the salt tolerance of maize seeds. Nanozymes are a class of nanomaterials with enzyme-like catalytic activity. Soaking seeds with nanozymes will affect the changes in metabolites and signal transduction pathways in seeds, which not only affects the growth during the germination and seedling stages but also affects the entire plant life cycle. In our previous study, it was found that silver nanoparticles have peroxidase-like activity and can catalyze the production of reactive oxygen species (Yan et al., 2022). Zhou et al. (2022) showed that soaking pakchoi seeds with 20 and 40 mg / L of silver nanoparticles significantly promoted the germination and seedling development of pakchoi seeds. Therefore, we speculate that the silver-silicon nanocomposite material can combine the advantages of each material itself, and through the reactive oxygen species generated by catalysis as stress signal molecules, trigger a stress response, promote seed germination, and improve the stress resistance of plants, which has potential application prospects in agriculture.

[0004] It solves the problems of long breeding time for current drought-resistant varieties, high cost of using chemical commercial plant growth regulating additives, limited effects, and environmental pollution. At the same time, it provides a scientific basis and technical support for the application of nanomaterials in agriculture. Summary of the Invention

[0005] Based on the above problems, the purpose of the present invention is to provide a silver-silicon nanocomposite material, a preparation method thereof, and an application thereof. Before sowing, soaking maize seeds in a suspension of Ag@SiO2 nanoparticles at a certain concentration can significantly improve the drought resistance of maize during the germination period.

[0006] To achieve the above purpose, the present invention provides the following technical solutions.

[0007] One aspect of the present invention provides a method for preparing a silver-silicon nanocomposite material, which is prepared by a sol-gel method. The nanomaterial is spherical and quasi-spherical. The method comprises the following steps:

[0008] S1: Dissolve starch in water, adjust the pH value to 11 using sodium hydroxide, and add a silver nitrate solution during heating and stirring to obtain a silver nanosol.

[0009] S2: Drop an ethanol solution containing water into tetraethyl orthosilicate, and then drop the resulting solution into the above silver nanosol. Continuously stir during this period, and finally add ammonia water to form a precipitate. After washing, drying, and grinding the reaction product into powder, the silver-silicon nanocomposite material Ag@SiO2 NPs is obtained.

[0010] Preferably, in step S1, the material ratio of the added starch to water is 0.5 g: 100 mL.

[0011] Preferably, in step S1, the heating and stirring temperature is 70 °C, and the concentration of the silver nitrate solution is 2% w / v.

[0012] Preferably, in step S2, the volume ratio of the added ethanol, water, and tetraethyl orthosilicate is 400:85:200.

[0013] Preferably, the drying conditions in step S2 are: temperature 40 °C, time 24 - 48 h.

[0014] Another aspect of the present invention also provides an application of the silver-silicon nanocomposite material in improving the drought resistance of corn seed germination. The silver-silicon nanocomposite material is prepared according to the method in the above technical solution.

[0015] Preferably, the application specifically comprises the following steps:

[0016] (1) Seed screening: Screen out corn seeds with uniform size and plump grains, and remove shriveled and damaged seeds.

[0017] (2) Seed disinfection: Disinfect the screened corn seeds with a sodium hypochlorite solution, and then rinse them repeatedly with ultrapure water until clean.

[0018] (3) Seed soaking treatment: Put the disinfected corn seeds into a silver-silicon nanocomposite material solution with a concentration of 20 - 100 mg / L for seed soaking treatment.

[0019] (4) Germination test: Germinate the seeds obtained in step (3).

[0020] Preferably, the preparation process of the silver-silicon nanocomposite solution in step (3) is as follows: place the silver-silicon nanocomposite particles in ultrapure water and ultrasonically treat them for 10 to 30 minutes.

[0021] Preferably, the material-liquid ratio of the corn seeds to the silver-silicon nanocomposite solution in step (3) is 1 g: 5 mL.

[0022] Preferably, the seed soaking conditions in step (3) are as follows: rotation speed 100 rpm, temperature 25 °C, time 24 h, in the dark condition.

[0023] Preferably, the specific process of the germination treatment in step (4) is as follows: after the seed soaking is completed, place the corn seeds in a petri dish lined with filter paper, add 3 mL of water or 3 mL of 10-20% PEG to the petri dish, and then place it in an incubator at 25 °C for dark germination for 7 days.

[0024] Compared with the prior art, the beneficial effects obtained by the present invention are as follows:

[0025] The present invention uses the sol-gel method to prepare Ag@SiO2 nanoparticles. This method has the advantages of simple operation, low cost, large yield, good material dispersion, etc. Soaking corn seeds in a suspension of Ag@SiO2 nanoparticles with a certain concentration before sowing can significantly improve the drought resistance of corn during the germination period. The seed treatment technology of the present invention is simple to operate, can shorten the average time of seed germination; improve the germination rate and vigor index of seeds; increase the root length of seedlings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a scanning electron microscope image (SEM) of the silver-silicon nanocomposite prepared according to Example 1 of the present invention;

[0027] Figure 2 It is the influence of soaking seeds with different concentrations of Ag@SiO2 NPs obtained according to Example 1 on the germination of corn under normal environment. Among them, A is the germination diagram, B is the germination rate diagram, C is the vigor index diagram, and D is the bud length and root length diagram;

[0028] Figure 3 It is the influence of soaking seeds with Ag@SiO2 NPs obtained according to Example 1 on the germination of corn under drought stress. Among them, A is the germination diagram, B is the germination rate diagram, C is the vigor index diagram, and D is the bud length and root length diagram.

[0029] Note: Use the t-test for data statistical analysis. * represents p <0.05, ** represents p <0.01, *** represents p <0.001. EMBODIMENTS

[0030] The following will describe the technical solutions in the embodiments of the present invention clearly and completely in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Embodiment

[0031] 1. Materials and Methods

[0032] 1.1 Preparation of silver-silica nanocomposites (Ag@SiO2 NPs)

[0033] Take 0.5 g of starch and dissolve it in 100 mL of deionized water, then add 0.25 g of sodium hydroxide to make the pH value of the solution reach 11. Continuously stir the starch solution, and when the temperature is heated to 70 °C, add a 2% w / v silver nitrate solution to obtain a silver nanosol. Mix 400 mL of ethanol and 85 mL of water, and then drop it into 200 mL of tetraethyl orthosilicate (TEOS). The resulting solution is dropped into the silver nanosol under continuous stirring, and then ammonia water is added to form a precipitate. Finally, the precipitate is rinsed 5 times with deionized water, dried at 40 °C for 24 h, and ground into powder with a quartz mortar to obtain the silver-silica nanocomposite Ag@SiO2 NPs.

[0034] 1.2 Preparation of seed soaking solution

[0035] Weigh a certain amount of the above-synthesized Ag@SiO2 NPs with an analytical balance and dissolve it in deionized water, and ultrasonically disperse it for 10 - 20 minutes to prepare suspensions of 20, 40, 80, and 100 mg / L respectively, which are the seed soaking solutions.

[0036] 1.3 Germination test

[0037] Take the corn variety "Jingnuo No. 1" as the test material. Select corn seeds with uniform size and plump grains, and remove shriveled and damaged seeds. Disinfect the selected corn seeds with 5% sodium hypochlorite for 10 min, and then rinse them thoroughly with deionized water. Soak the seeds in the Ag@SiO2 NPs suspensions of 0, 20, 40, 80, and 100 mg / L for 24 h respectively, and the ratio of seed mass to the volume of the seed soaking solution is 1:5. After soaking, take out the seeds and rinse them once with deionized water, and then place them in a petri dish (diameter 9 cm) lined with a layer of filter paper. Put 20 seeds in each petri dish and add 3 mL of deionized water. Set 4 replicates for each treatment, and place them in a dark incubator at 25 °C to germinate for 7 days, and count the germination rate of each treatment every day.

[0038] The germination test method under drought stress is the same as above. The difference is that the concentration of the seed soaking solution used is 80 mg / L Ag@SiO2 NPs (the optimal concentration selected according to the experimental results). The control group is soaked with deionized water, and 3 mL of PEG solution is added to the petri dish to simulate the drought environment.

[0039] 1.4 Index determination

[0040] The germination rate of maize seeds in each treatment was counted every day. Germination was considered when the shoot length or root length exceeded half of the seed.

[0041] The shoot length and root length of the seedlings were measured with a millimeter ruler.

[0042] The seed vigor was calculated according to the following formula: Seed vigor = (root length + shoot length) × germination rate cm %.

[0043] The fresh weights of the shoots and roots were measured with an analytical balance, and the dry weights were measured after drying at 60 °C for 24 h. The moisture content was calculated according to the following formula: Moisture content (%) = (fresh weight - dry weight) / fresh weight × 100

[0044] 2. Results and analysis

[0045] 2.1 Characterization of Ag@SiO2 NPs

[0046] Figure 1 Shown is the scanning electron microscope image of Ag@SiO2 NPs obtained according to the method in Example 1. From Figure 1 It can be seen that the shape of Ag@SiO2 NPs is roughly spherical, the particle size is relatively uniform, and the particle diameter is between 375 and 445 nm. The hydrodynamic diameter of Ag@SiO2 NPs (80 mg / L) measured by dynamic light scattering (DLS) is 2242.8 ± 368 nm, and the Zeta potential is -43.07 ± 0.41 mV.

[0047] 2.2 Effects of Ag@SiO2 NPs seed soaking solutions with different concentrations on maize seed germination

[0048] Figure 2 Shows the effects of Ag@SiO2 NPs seed soaking solutions with different concentrations obtained according to Example 1 on the germination rate (B), vigor index (C), shoot length, and root length (D) of maize seeds. From Figure 2 It can be seen that soaking seeds with Ag@SiO2 NPs accelerated the germination of maize seeds ( Figure 2 B). Among them, under the treatment of 100 mg / L Ag@SiO2 NPs, the germination rate of maize seeds (98.75%) was significantly higher than that of the control group (93.75%). Treatments with 80 mg / L and 100 mg / L Ag@SiO2 NPs significantly increased the seed vigor index ( Figure 2C), which were increased by 10.5% and 14.4% respectively compared with the control. At the same time, the Ag@SiO2 NPs treatments at 80 and 100 mg / L also significantly increased the root length of the seedlings ( Figure 2 D), which were increased by 14.6% and 13.6% respectively compared with the control. Therefore, within a certain concentration range, the Ag@SiO2 NPs seed soaking treatment can promote the germination and growth of maize seeds. Since the promoting effects of 80 mg / L and 100 mg / L Ag@SiO2 NPs on maize seed germination were similar, 80 mg / L was finally selected as the optimal concentration for subsequent experiments, while saving costs.

[0049] 2.3 Effects of Ag@SiO2 NPs seed soaking on the drought resistance of maize seeds during the germination period

[0050] Figure 3 The effects of Ag@SiO2 NPs seed soaking on the germination rate (B), vigor index (C), shoot length and root length (D) of maize seeds under different degrees of drought stress are shown. As can be seen from the figure, drought stress significantly reduced the germination speed, germination rate, shoot length and root length of maize seeds. Under the drought stress of 10% PEG, the Ag@SiO2 NPs seed soaking treatment at 80 mg / L significantly increased the germination rate (5.4%) of maize seeds ( Figure 3 B), the vigor index of the seeds (24.4%) ( Figure 3 C), and the root length (20.8%) ( Figure 3 D). Therefore, the Ag@SiO2 NPs seed soaking treatment at 80 mg / L improved the growth indexes such as the germination rate, vigor index and root length of maize seeds under drought stress, and enhanced the drought resistance of maize seeds under drought stress.

[0051] The details not described in the present invention are all well-known technologies in the art.

[0052] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified and equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. Application of a silver-silicon nanocomposite in improving drought resistance of maize seed germination, characterized in that, The silver-silicon nanocomposite is prepared by the sol-gel method. The silver-silicon nanocomposite is spherical and quasi-spherical. The preparation method of the silver-silicon nanocomposite includes the following steps: S1: Dissolve starch in water, adjust the pH value to 11 using sodium hydroxide, and add silver nitrate solution during heating and stirring to obtain a silver nanosol; S2: Drop an ethanol solution containing water into tetraethyl orthosilicate, and then drop the obtained solution into the above silver nanosol. Continuously stir during this period, and finally add ammonia water to generate a precipitate. After washing, drying, and grinding the reaction product into powder, the silver-silicon nanocomposite Ag@SiO2 NPs is obtained; In step S1, the heating and stirring temperature is 70 °C, and the concentration of the silver nitrate solution is 2% w / v; In step S2, the volume ratio of ethanol, water, and tetraethyl orthosilicate added is 400:85:200; The specific application includes the following steps: (1) Seed screening: Screen out corn seeds with uniform size and plump grains, and remove shriveled and damaged seeds; (2) Seed disinfection: After disinfecting the screened corn seeds with sodium hypochlorite solution, rinse them repeatedly with ultrapure water; (3) Seed soaking treatment: Put the disinfected corn seeds into a silver-silicon nanocomposite solution with a concentration of 20-100 mg / L for seed soaking treatment; (4) Germination test: Germinate the seeds obtained in step (3).

2. The application according to claim 1, wherein In step S1, the material-liquid ratio of starch and water added is 0.5 g: 100 mL.

3. The application according to claim 1, wherein The drying conditions in step S2 are: temperature 40 °C, time 24-48 h.

4. The application according to claim 1, characterized in that, In step (3), the material-liquid ratio of corn seeds and silver-silicon nanocomposite solution is 1 g: 5 mL.

5. The application according to claim 1, wherein The seed soaking conditions in step (3) are: rotation speed 100 rpm, temperature 25 °C, time 24 h, dark condition.

6. The application according to claim 1, characterized in that The specific process of the germination treatment in step (4) is: After the seed soaking is completed, place the corn seeds in a petri dish lined with filter paper, add 3 mL of water or 3 mL of 10-20% PEG to the petri dish, and then place it in an incubator at 25 °C for dark germination for 7 days.

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