Preparation method of rod-like selenium nano-carrier

Abstract

The invention discloses a preparation method of a rod-like selenium nano-carrier, and belongs to the technical field of nano-pesticides. The rod-like selenium nano-carrier is formed by converting chitosan modified amorphous selenium (a-Se) into single crystal ash selenium (t-Se). The amorphous selenium is initially spherical, and after chitosan modification, the spherical amorphous selenium is converted into single crystal ash rod-shaped selenium nanoparticles. The length of the rod-like selenium nano-carrier is 590-610 nm, the diameter of the rod-like selenium nano-carrier is 20-25 nm, the effective average particle size of the rod-like selenium nano-carrier is 90-110 nm, the drug loading rate is 39.28% + / -2%, and the encapsulation efficiency is 64.90% + / -3%. In addition, the invention also provides an application of the rod-like selenium nano-carrier in a nano bactericide material.

Description

Technical Field

[0001] The invention belongs to the technical field of nano pesticides and discloses a method for preparing rod-shaped selenium nano carrier particles. Technical Background

[0002] Selenium is a trace element necessary for plant growth and development. Selenium nanoparticles are less toxic than inorganic and organic selenium and can promote plant growth. However, the traditional nanomaterials composed of amorphous selenium (a-Se) have problems such as easy agglomeration, uneven particle size distribution, and unstable structure, which limits their application in a wider range of fields. In contrast, nanomaterials composed of single-crystal gray selenium (t-Se) have higher thermodynamic stability and therefore have significant potential in their development and application.

[0003] To date, many chemical methods have been proposed for the synthesis of nanomaterials composed of single-crystalline gray selenium, but due to the lateral growth characteristics of single-crystalline gray, most existing methods have challenges in controlling their length and diameter. Compared with nanowires of unknown length, rod-shaped nanoparticles with a size less than 200 nm have better pharmacokinetic and better fungal enrichment in vivo, and the latest studies have shown that the length and diameter of rod-shaped nanoparticles have an important influence on the physicochemical properties of the material and its effects in different applications. If the size distribution is uneven, the material may exhibit unstable performance and low efficiency. Therefore, it is crucial to further develop green, controllable and efficient synthesis technology of rod-shaped selenium nanoparticles. Summary of the invention

[0004] In order to achieve uniform rod-shaped size distribution of selenium nanomaterials and improve the bioavailability of pesticides loaded by selenium nanomaterials, the present invention provides a method for preparing a rod-shaped selenium nanocarrier.

[0005] The preparation steps of a rod-shaped selenium nanocarrier are as follows:

[0006] (1) Dissolve the selenium source in pure water at a mass volume ratio of 0.2-0.4 g:40 mL, add glucose while stirring, and then add chitosan solution with a mass volume concentration of 5 mg / mL dropwise, react at room temperature to obtain a mixed solution;

[0007] The selenium source is sodium selenite;

[0008] The reducing agent is glucose;

[0009] The mass ratio of the selenium source to the reducing agent is 1:1 to 2:1;

[0010] The mass ratio of the selenium source to chitosan used is 30:1 to 40:1;

[0011] (2) heating the mixed solution to obtain a hot turbid brick red solution, rapidly cooling it, and centrifuging it to obtain an amorphous selenium precursor;

[0012] (3) adding the amorphous selenium precursor to anhydrous ethanol at a mass volume ratio of 1 mg:1 mL, ultrasonically treating the mixture, and standing the mixture at room temperature to react to obtain a reaction solution;

[0013] (4) centrifuging the reaction solution, collecting the precipitate, and drying it in an oven to obtain black-brown rod-shaped selenium nanocarrier particles composed of single crystal gray;

[0014] The rod-shaped selenium nanocarrier particles have a length of 590-610 nm, a diameter of 20-25 nm, an effective average particle size of 90-110 nm, a drug loading rate of 39.28%±2%, and an encapsulation rate of 64.90%±3%.

[0015] The further technical solution is as follows:

[0016] In step (1), 0.24 g of sodium selenite is dissolved in 40 mL of pure water, 0.2 g of glucose is added while stirring on a magnetic stirrer, and then 1.4 mL of a chitosan solution with a mass volume concentration of 5 mg / mL is added dropwise; stirring is carried out for 20 min at room temperature and 300-500 rad / min.

[0017] The mass ratio of sodium selenite to glucose is 1.2:1;

[0018] The mass ratio of selenium source to chitosan used was 34:1;

[0019] In step (2), the reaction is carried out in an oven at 60° C. for 12 h.

[0020] In step (3), the ultrasonic treatment conditions are as follows: ultrasonic power 300-400 W, time 15 min; and the reaction is allowed to stand at room temperature for 24 h.

[0021] In step (4), the centrifugation conditions are: rotation speed of 10000 rpm, time of 10 min; and drying conditions are: temperature of 85°C, time of 3 to 4 h.

[0022] The beneficial technical effects of the present invention are embodied in the following aspects:

[0023] 1. The preparation method of the present invention converts amorphous selenium (a-Se) into single-crystal gray selenium (t-Se) by chitosan modification to form a rod-shaped selenium nanocarrier, which solves the problem of easy agglomeration and structural instability of amorphous selenium. The prepared rod-shaped selenium nanocarrier has a length of 590-610 nm, a diameter of 20-25 nm, an effective average particle size of 90-110 nm, and a uniform and stable size. The controllability of size and morphology is achieved by chitosan regulation, ethanol system and ultrasonic treatment technology. The prepared rod-shaped selenium nanocarrier has a drug loading rate of 39.28%±2% and an encapsulation rate of 64.90%±3%, which effectively improves the loading and transfer efficiency of pesticides. In addition, strict control of the power and time of ultrasonic action not only helps to destroy aggregates, but also promotes the conversion of amorphous selenium to rod-shaped selenium by increasing the kinetic energy of the system, and the subsequent heating reaction ensures the further growth and morphological stability of the particles. By heating in an oven, the increase in temperature can accelerate the diffusion of atoms or molecules, so that the preliminary structure formed after ultrasonic treatment can be fully rearranged and grown, thereby achieving precise control of the length. Controlling the heating time and temperature helps to accurately set the length of the rod-shaped selenium within the range of 590 to 610 nm to ensure its size uniformity. In addition, heating can also promote the formation of a more ordered crystal structure and enhance the stability of the material. Therefore, the combination of ultrasound and oven heating is a key step in achieving uniform and stable rod-shaped selenium nanocarriers.

[0024] 2. The preparation method of the present invention is green and environmentally friendly. Chitosan and glucose are used as modifiers and reducing agents, avoiding the pollution problem in traditional chemical synthesis. In addition, chitosan, as a natural polysaccharide, has good biocompatibility and biodegradability. In the preparation process, chitosan not only acts as a modifier, but also interacts with amorphous selenium (a-Se) through its cationic properties to form a stable complex. The presence of chitosan helps to inhibit the agglomeration of selenium particles, promote their uniform dispersion, and form a more ordered crystal structure in the reaction, thereby converting it into single crystal gray selenium (t-Se). Glucose, as a reducing agent, can effectively reduce sodium selenite to generate amorphous selenium. During the reaction, the reducing effect of glucose helps to control the precipitation rate of selenium, thereby obtaining a more uniform particle size. The mild reducing environment of glucose avoids the inhomogeneity and structural damage that may occur under high temperature or strong reducing conditions.

[0025] 3. The present invention loads penthiopyrad on a rod-shaped selenium nanocarrier to prepare a rod-shaped selenium nanopesticide, which is beneficial to improving the antibacterial activity and bioavailability of the pesticide. The rod-shaped selenium nanocarrier of the present invention has high application potential, especially in the field of nanopesticides and antibacterial materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Transmission electron microscope images of the three substances.

[0027] Figure 1 A is a transmission electron microscopy image of the rod-shaped selenium nanocarrier, B is a transmission electron microscopy image of the reaction product B, and C is a transmission electron microscopy image of the reaction product C.

[0028] Figure 2 Zeta potential diagram of rod-shaped selenium nanocarriers and rod-shaped selenium nanopesticides.

[0029] Figure 3 This is the Fourier infrared spectra of rod-shaped selenium nanocarriers and rod-shaped selenium nanopesticides.

[0030] Figure 4 This is a graph showing the drug loading rate and encapsulation efficiency of rod-shaped selenium nanocarriers.

[0031] Figure 5 This is the pesticide release curve of rod-shaped selenium nanopesticide under different pH conditions.

[0032] Figure 6 The diagram shows the inhibitory effect on the mycelial growth of various fungi. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0034] Unless otherwise specified, the reagents used in the following examples can be purchased from the market.

[0035] Example 1

[0036] The preparation steps of a rod-shaped selenium nanocarrier are as follows:

[0037] S1. Weigh 0.24 g of sodium selenite and dissolve it in 40 mL of pure water. Add 0.2 g of glucose while stirring, and then add 1.4 mL of chitosan solution with a mass volume concentration of 5 mg / mL dropwise. Stir vigorously at room temperature and 500 rad / min for 20 min to obtain a mixed solution.

[0038] The mass ratio of sodium selenite to glucose is 1.2:1;

[0039] The mass ratio of selenium source to chitosan used was 34:1;

[0040] S2. In an oven, the mixed solution was reacted at 60°C for 12 h to obtain a hot turbid brick-red solution. The solution was rapidly cooled and the precipitate was collected by centrifugation to obtain an amorphous selenium precursor.

[0041] S3. Add the amorphous selenium precursor into 20 mL of anhydrous ethanol, perform ultrasonic treatment at a power of 400 W for 15 min, and allow to react at room temperature for 24 h to obtain a reaction solution.

[0042] S4. The reaction solution was centrifuged at a speed of 10,000 rpm for 10 min and placed in an oven at 85° C. for 4 h to obtain the rod-shaped selenium nanocarrier composed of the single crystal ash. The rod-shaped selenium nanocarrier was in the form of dark brown particles.

[0043] The length of the rod-shaped selenium nanocarrier particles is 590-610 nm, the diameter is 20-25 nm, and the effective average particle size is 90-110 nm.

[0044] The operation of preparing rod-shaped selenium nanopesticide using the rod-shaped selenium nanocarrier of Example 1 is as follows:

[0045] 10 mg of rod-shaped selenium nanocarriers were dispersed in 10 mL of pure water, and 1 mL of penthiopyrad liquid (10 mg / mL) dissolved in anhydrous ethanol was added dropwise. The mixture was mixed and stirred for 12 h, and centrifuged at 10000 rpm for 10 min. The supernatant was removed, and the precipitate was washed 3 times with pure water and freeze-dried to obtain rod-shaped selenium nanopesticides.

[0046] The drug loading rate of rod-shaped selenium nanocarriers in rod-shaped selenium nanopesticides was 39.28%±2%, and the encapsulation efficiency was 64.90%±3%.

[0047] See also Figure 1 The rod-shaped selenium nanocarrier prepared in Example 1 has a length of 590-610 nm, a diameter of 20-25 nm, and an effective average particle size of 90-110 nm, which is conducive to fungal cell penetration.

[0048] See also Figure 2 , with the loading of pesticides, the potential of rod-shaped Se nanocarriers decreased from +16.31 mV to -3.74 mV, indicating that the loading of pesticides changed the zeta potential of Se nanocarriers, and the negative potential was beneficial for targeting fungal cells.

[0049] See also Figure 3 The characteristic peak at about 3450-3390 cm-1 is due to the stretching vibration of NH, and the characteristic peak at 1640 cm-1 is a typical absorption peak of C=C stretching vibration. The stretching vibrations of CF and CH can be attributed to the obvious peaks at 1400-730 cm-1 and 2940-2930 cm-1, respectively. The penthiopyrad group was successfully modified onto the surface of the rod-shaped selenium nanocarrier. The results showed that the rod-shaped selenium nanopesticide was successfully prepared by the rod-shaped selenium nanocarrier of Example 1.

[0050] See also Figure 4 The drug loading rate of the rod-shaped selenium nanocarrier in Example 1 was 39.28%±2%, and the encapsulation efficiency was 64.90%±3%.

[0051] The drug release experiment of penthiopyrad was carried out by UV-visible spectroscopy to determine the release amount by detecting the absorbance of penthiopyrad molecules at different time intervals. Briefly, 1 mg of selenium nanocarrier particles loaded with penthiopyrad were weighed and placed at the bottom of the dialysis bag of MWCO6000, and then immersed in a beaker containing phosphate buffered saline solutions with pH values ​​of 3, 5, and 7 at 25°C with a stirring speed of 100 rpm to activate the chitosan control barrier. The maximum absorption wavelength of penthiopyrad is 227 nm, and the amount of released penthiopyrad can be determined by a standard curve made from the concentration of penthiopyrad dissolved in phosphate buffered saline solution at pH=7 and the absorbance of penthiopyrad.

[0052] See also Figure 5 , the cumulative release rates of rod-shaped selenium nanopesticides were 47.32%, 36.04% and 19.34% after 96 h at pH values ​​of 3, 5 and 7, respectively. According to these findings, the cumulative release of rod-shaped selenium nanopesticides in acidic media was greater than that in neutral solutions. Using different kinetic models for the release of penthiopyrad, the cumulative release curves of rod-shaped selenium nanopesticides under different conditions were fitted to further study the release kinetics of nanopesticides.

[0053] Table 1 Fitting results of the release of penthiopyrad from rod-shaped selenium nanocarrier particles loaded with penthiopyrad under different conditions

[0054]

[0055] Table 1 shows the fitting results of the Zero-order, First-order, Higuchi and Ritager-Peppas models for the release of penthiopyrad from rod-shaped selenium nanocarrier particles loaded with penthiopyrad under different pH values. The results show that the Ritger-Peppas release model fits the release process of the original drug and the drug-loaded particles better than the Higuchi, Zero-order and First-order models. The Ritger-Peppas release model analyzes the release behavior of the pesticide by judging the diffusion index (K). When K ≤ 0.45, diffusion is dominant; 0.45 < K < 0.89, there are two behaviors, diffusion and dissolution; K > 0.89, dissolution is dominant. The K values ​​of rod-shaped selenium nanopesticides at pH = 3, 5 and 7 are 0.23, 0.25 and 0.44, respectively, indicating that rod-shaped selenium nanopesticides transmit penthiopyrad by simple diffusion and can be released more effectively under acidic conditions. Since fungal infection leads to an acidic environment, this property helps to achieve targeted release of pesticides, thereby enhancing their antibacterial activity.

[0056] Example 2

[0057] S1. The operation is the same as in Example 1 to obtain a mixed solution.

[0058] S2. The operation is the same as in Example 1 to obtain an amorphous selenium precursor.

[0059] S3. Other operations are the same as those in Example 1, except that ultrasonic treatment is performed for 30 min to obtain a reaction solution.

[0060] S4. The other operations are the same as those in Example 1, except that the drying time is 2 h, and the reaction product B consisting of the single crystal ash is obtained.

[0061] See also Figure 1 The reaction product B is in the form of short rod-shaped selenium nanoparticles with a length of 160 to 200 nm, a diameter of 8 to 10 nm, and an effective average particle size of 40 to 50 nm.

[0062] The operation of preparing selenium nanopesticide using reaction product B is as follows:

[0063] 10 mg of reaction product B was dispersed in 10 mL of pure water, and then 1 mL of penthiopyrad liquid (10 mg / mL) dissolved in anhydrous ethanol was added dropwise. After mixing, it was stirred for 12 h, centrifuged at 10000 rpm for 10 min, the supernatant was removed, and the precipitate was washed 3 times with pure water, freeze-dried, and collected to obtain selenium nanopesticide.

[0064] Comparative Example 1

[0065] S1. Weigh 0.24 g of sodium selenite and dissolve it in 40 mL of pure water. Add 0.2 g of glucose while stirring, and then add 1.4 mL of chitosan solution with a mass volume concentration of 5 mg / mL. Stir vigorously at room temperature for 20 min to obtain a mixed solution.

[0066] The mass ratio of sodium selenite to glucose is 1.2:1;

[0067] The mass ratio of selenium source to chitosan used was 34:1;

[0068] S2. The mixed solution was reacted in an oven at 60°C for 12 h to obtain a hot turbid brick red solution. The solution was rapidly cooled and the precipitate was collected by centrifugation to obtain an amorphous selenium precursor.

[0069] S3. The prepared amorphous selenium precursor was added to 20 mL of anhydrous ethanol, and ultrasonically treated at a power of 400 W for 30 min. The reaction was allowed to stand at room temperature for 24 h to obtain a reaction solution.

[0070] S4. The reaction solution was centrifuged at 10,000 rpm for 10 min, and placed in an oven at 85° C. for 6 h to obtain the reaction product C consisting of the single crystal ash.

[0071] See also Figure 1 C in the figure is a transmission electron microscope image of the reaction product C, which is in the form of selenium nanowires.

[0072] The operation of preparing selenium nanopesticide using reaction product C is as follows:

[0073] 10 mg of the reaction product C was dispersed in 10 mL of pure water, and then 1 mL of penthiopyrad liquid (10 mg / mL) dissolved in anhydrous ethanol was added dropwise, mixed and stirred for 12 h, and then centrifuged at 10000 rpm for 10 min, the supernatant was removed, and the precipitate was washed 3 times with pure water, freeze-dried, and collected to obtain Comparative Example 1.

[0074] Figure 6 The results show the inhibitory effects of 20% pentiopyrad suspension with an effective concentration of 2.5 mg / L of pentiopyrad, rod-shaped selenium nanopesticide, Example 2 and Comparative Example 1 on the hyphae growth of anthrax, sclerotinia and sheath blight.

[0075] The present invention adopts the mycelium growth inhibition experiment to evaluate the inhibitory effect of 20% penthiopyrad suspension, rod-shaped selenium nanopesticide, Example 2 and Comparative Example 1 on anthrax, sclerotinia and sheath blight. The results show that, under the same effective concentration of penthiopyrad, compared with 20% penthiopyrad suspension, rod-shaped selenium nanopesticide, Example 2 and Comparative Example 1 all show stronger inhibitory effect on anthrax, sclerotinia and sheath blight. It is worth noting that the antibacterial activity of rod-shaped selenium nanopesticide is the strongest. This difference in antifungal activity is related to the morphology and drug loading capacity of the rod-shaped selenium nanocarrier. The unique shape of the rod-shaped selenium nanocarrier can affect the integrity of the lipid membrane. In addition, the rod-shaped morphology increases the particle surface area, thereby improving the drug loading capacity.

[0076] It will be easily understood by those skilled in the art that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a rod-shaped selenium nanocarrier, characterized in that: The steps are as follows: (1) Dissolve the selenium source in pure water at a mass volume ratio of 0.2-0.4 g:40 mL, add glucose while stirring, and then add chitosan solution with a mass volume concentration of 5 mg / mL dropwise, react at room temperature to obtain a mixed solution; The selenium source is sodium selenite; The reducing agent is glucose; The mass ratio of the selenium source to the reducing agent is 1:1 to 2:1; The mass ratio of the selenium source to chitosan used is 30:1 to 40:1; (2) heating the mixed solution to obtain a hot turbid brick red solution, rapidly cooling it, and centrifuging it to obtain an amorphous selenium precursor; (3) adding the amorphous selenium precursor to anhydrous ethanol at a mass volume ratio of 1 mg:1 mL, ultrasonically treating the mixture, and standing the mixture for reaction at room temperature to obtain a reaction solution; (4) centrifuging the reaction solution, collecting the precipitate, and drying it in an oven to obtain a rod-shaped selenium nanocarrier composed of single crystal ash, which is in the form of dark brown particles; The rod-shaped selenium nanocarrier particles have a length of 590-610 nm, a diameter of 20-25 nm, an effective average particle size of 90-110 nm, a drug loading rate of 39.28%±2%, and an encapsulation rate of 64.90%±3%.

2. The method for preparing a rod-shaped selenium nanocarrier according to claim 1, characterized in that: In step (1), 0.24 g of sodium selenite is dissolved in 40 mL of pure water, 0.2 g of glucose is added while stirring on a magnetic stirrer, and then 1.4 mL of a chitosan solution with a mass volume concentration of 5 mg / mL is added dropwise; stirring is carried out for 20 minutes at room temperature and 300-500 rad / min.

3. The method for preparing a rod-shaped selenium nanocarrier according to claim 1, characterized in that: In step (2), the reaction is carried out in an oven at 60° C. for 12 h.

4. The method for preparing a rod-shaped selenium nanocarrier according to claim 1, characterized in that: In step (3), the ultrasonic treatment conditions are as follows: ultrasonic power 300-400 W, time 15 min; and the reaction is allowed to stand at room temperature for 24 h.

5. The method for preparing a rod-shaped selenium nanocarrier according to claim 1, characterized in that: In step (4), the centrifugation conditions are: rotation speed of 10000 rpm, time of 10 min; and the drying conditions are: temperature of 85°C, time of 3 to 4 h.

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