Compound halloysite nanotube essential oil sustained-release tablet with long-acting antibacterial performance and preparation method of compound halloysite nanotube essential oil sustained-release tablet
By loading clove essential oil into Elosite nanotubes and combining it with kaolin and concave rods and then forming the tablet, the problems of volatile and limited application of clove essential oil are solved, and the long-term sustained release and antibacterial effects are improved. It is suitable for biological control and health protection in various fields.
Patent Information
- Application Number
- CN202411822312.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-11
- Publication Date
- 2025-04-25
AI Technical Summary
Lilac essential oil is easy to volatile, poor water solubility, strong photosensitive, and has limited application, making it difficult to be directly used in the field of biological control.
Elosite nanotubes were used as carriers, and clove essential oil was loaded into the nanotubes by acid etching, aminization and cyclic negative pressure methods to prepare antibacterial nanoparticles, and then combined with kaolin and concave rods and molded through tableting.
It has achieved the long-term sustained release and antibacterial effects of clove essential oil, improved the stability and application breadth of essential oils, and is suitable for agricultural prevention and control, food processing and medical device disinfection.
Smart Images
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of nano-loaded materials, in particular to a composite halloysite nanotube essential oil sustained-release tablet with long-acting antibacterial performance and a preparation method thereof. Background Art
[0002] Numerous studies have confirmed that clove essential oil has broad-spectrum antibacterial properties. Due to its lipophilicity, it contacts the cell membrane, and the hydroxyl functional groups on eugenol interact with the cell membrane, causing damage to the integrity of the cell membrane, leakage of intracellular contents, and death of the bacteria. Clove essential oil can effectively inhibit a variety of pathogenic microorganisms such as Gram-negative bacteria, Gram-positive bacteria, Aspergillus, Penicillium, Candida albicans and yeast, and also has anti-termite and anti-parasitic effects. Clove essential oil has a stronger inhibitory activity against Gram-positive bacteria, which is attributed to a diffusible mucopeptide layer in Gram-positive bacteria, making them more sensitive to antibacterial agents. However, eugenol is volatile at room temperature, has poor water solubility, is highly photosensitive, and has a musky smell. Repeated use is prone to waste of raw materials, which greatly limits its application and cannot be directly applied to the field of biological control. Therefore, loading eugenol in a suitable carrier material can effectively solve the shortcomings of clove essential oil such as volatility and expand its application field.
[0003] Halloysite nanotubes (HNTs) are natural multi-walled nanotubes, which are silicate minerals. Their crystal structure is similar to that of kaolinite, and they are dioctahedral structures with 1:1 structural unit layers. They have a unique hollow tubular structure, with an inner diameter of about 15-20 nm, an outer diameter of about 30-50 nm, and a length of about 500-1500 nm, which has a high aspect ratio. They have the characteristics of high specific surface area, rich pore structure, strong adsorption capacity, non-toxicity, excellent electrical conductivity, mechanical properties and chemical stability. They are used in the control and sustained release of a variety of drugs or bioactive molecules. They are abundant in reserves, easy to take, and non-toxic and side effects. At the same time, they have excellent mechanical properties and biocompatibility, and are very economical compared to carbon nanotubes (CNTs). Therefore, this material has been widely studied and used in the fields of composite materials, sensors, biomedicine, medical implants, pesticides, specific ion adsorbents, dyes and drugs in wastewater or bio-based samples. By controlling its structure and composition, its performance can be regulated and optimized, providing broad prospects for the sustained-release application of essential oils. Summary of the invention
[0004] The purpose of the present invention is to provide a method for preparing an antibacterial sustained-release tablet using halloysite nanotubes as carriers to load clove essential oil, to produce antibacterial nanoparticles based on halloysite nanotubes loaded with clove essential oil and to carry out tableting after compounding, so as to have good antibacterial performance and long-term sustained-release effect, and to improve the effect of the essential oil.
[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: A composite halloysite nanotube essential oil sustained-release tablet with long-term antibacterial performance comprises antibacterial nanoparticles, kaolin and attapulgite. The antibacterial nanoparticles and clove essential oil are mixed, the antibacterial nanoparticles are mixed with kaolin and attapulgite, and a tablet press is used to obtain an antibacterial sustained-release tablet of clove essential oil loaded with halloysite nanotubes.
[0006] A method for preparing a composite halloysite nanotube essential oil sustained-release tablet with long-lasting antibacterial performance comprises the following steps: Step 1: Disperse 15 g of halloysite nanotubes HNTs in 150 mL of 20-30% H2O2, stir at 340 r for 1 h at room temperature, centrifuge at 10000 r / min to obtain a solid purified sample, dry it at 110 °C for 3 h, and vacuum dry it at 60 °C for 2 h. Step 2: Disperse 8-12 g of the purified halloysite nanotubes obtained in step 1 in 500 mL of a 10% nitric acid solution, and stir at 70° C. for 24-36 h to obtain acidified halloysite nanotubes; treat the halloysite nanotubes with a 10% nitric acid solution; Step 3, take 6-10 g of acidified halloysite nanotubes and disperse them in 200-300 mL of deionized water to form a halloysite nanotube suspension, take excess ammonia water and heat it, pass ammonia gas into the halloysite nanotube suspension through condensation reflux, add 3-12 drops of modifier 3-aminopropyltriethoxysilane, centrifuge at 10000 r / min for 10 min and wash with water three times until the pH is 7, dry with air at 120°C for 6.5 h, and vacuum dry at 60°C for 2 h to obtain amination of halloysite nanotubes HNTs-NH2 containing ammonium nitrate crystals inside; Step 4: Take the aminated halloysite nanotubes prepared in step 3, mix the aminated halloysite nanotubes with clove essential oil, and ultrasonically treat them at a power of 160-200 W for 20-30 min in an ice bath environment at 0-4°C, place them in a vacuum drying oven, and maintain the pressure under vacuum conditions for 20-30 min; open the vacuum valve to allow the clove essential oil to enter the lumen of the halloysite nanotubes; repeat the above steps 3-5 times, centrifuge and wash the surface clove essential oil with anhydrous ethanol, and freeze-dry for 36 h to obtain halloysite nanotube antibacterial nanoparticles CEO@HNTs-NH2 loaded with clove essential oil; Step 5: Mix the antibacterial nanoparticles CEO@HNTs-NH2 prepared in step 4 with kaolin and attapulgite, and use a tablet press to press the antibacterial sustained-release tablets of halloysite nanotubes loaded with clove essential oil at a pressure of 0.4-0.6 KPa.
[0007] In the step 4, the mixing ratio of the aminated halloysite nanotubes and the clove essential oil is 0.05-0.2 g / mL.
[0008] The vacuum condition in step 4 is a pressure of 0.1-1.0 MPa, and the centrifugal condition is 10000 r / min for 10 min.
[0009] In the step 5, the mass ratio of CEO@HNTs-NH2 antibacterial nanoparticles to attapulgite is 3 / 2, and the mass ratio of attapulgite to kaolin is 1 / 2-1 / 1.
[0010] The pressure of the tablet press described in step 5 is 0.4-0.6 MPa.
[0011] In the step 4, the mixture is placed in a vacuum drying oven DZF-6030A in an ice bath at 0-4°C under the environment of an IMS-50 fully automatic flake ice maker.
[0012] The method of the present invention first uses a 20-30% hydrogen peroxide solution to purify the halloysite nanotubes, then disperses them in a 10% nitric acid solution to acid-etch the halloysite nanotubes to increase their specific surface area and pore volume, thereby improving the loading capacity of the halloysite nanotubes; then the acidified halloysite nanotubes are dispersed in deionized water, and the ammonia water is heated to generate ammonia gas, and the overflowed ammonia gas is introduced into the halloysite nanotube dispersion by condensation reflux, and the aminated halloysite nanotubes are obtained after centrifugal washing. Then, by utilizing the hollow tubular structure of the halloysite nanotubes, eugenol is allowed to enter the aminated halloysite nanotube lumen by a cyclic negative pressure method, and antibacterial nanoparticles using halloysite nanotubes as carriers to load clove essential oil are prepared, and finally kaolin and attapulgite are added and mixed in proportion to form an antibacterial sustained-release tablet by tableting.
[0013] The antibacterial sustained-release tablet prepared by the present invention using halloysite nanotubes as carriers to load clove essential oil has good antibacterial effect. The loading of halloysite nanotubes can improve the long-term sustained-release effect of the essential oil, so that it can continuously act on root rot of Chinese herbal medicines.
[0014] The raw materials of the antibacterial sustained-release tablets with clove essential oil loaded by the halloysite nanotubes prepared by the present invention are green, pollution-free and low-cost. After acting on the soil environment, it has no effect on the original environment of the soil and will not cause secondary pollution, thereby alleviating the disadvantages brought by traditional agricultural prevention and control.
[0015] The antibacterial sustained-release tablet with clove essential oil loaded by the halloysite nanotubes prepared by the present invention adopts a composite material, and attapulgite is added to kaolin to ensure the plasticity and adhesion of the sustained-release tablet, while meeting the kaolin ratio of different root sizes, and can also increase the dimensional stability of the sustained-release tablet and save resources, which is conducive to industrial production. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 The FTIR image of the composite material of clove essential oil antibacterial nanoparticles loaded with halloysite nanotubes as carriers; Figure 2 TG graph of the composite material of clove essential oil antibacterial nanoparticles loaded with halloysite nanotubes as carrier; Figure 3 This is the SEM image of the composite material of clove essential oil antibacterial nanoparticles loaded with halloysite nanotubes as carriers; Figure 4 It is a line graph showing the effect of negative pressure on the loading rate of clove essential oil before and after modification of halloysite nanotubes; Figure 5 A schematic diagram of the composite material of clove essential oil antibacterial nanoparticles loaded with halloysite nanotubes as carriers; Figure 6 This is a diagram showing the sustained release effect of the composite material of clove essential oil antibacterial nanoparticles loaded with halloysite nanotubes as carriers; Figure 7 This is a graph showing the mechanical strength of the antibacterial sustained-release tablets with clove essential oil loaded on halloysite nanotubes as carriers; Figure 8 This is a test chart of the antibacterial effect of the antibacterial sustained-release tablets with clove essential oil loaded on halloysite nanotubes as carriers. DETAILED DESCRIPTION
[0017] The present invention is further described in detail below in conjunction with specific examples and verification of the products of the examples.
[0018] A composite halloysite nanotube essential oil sustained-release tablet with long-term antibacterial performance comprises antibacterial nanoparticles, kaolin and attapulgite. After the antibacterial nanoparticles and clove essential oil are mixed, the antibacterial nanoparticles are mixed with kaolin and attapulgite, and a tablet press is used to obtain an antibacterial sustained-release tablet of clove essential oil loaded on halloysite nanotubes. First, the halloysite nanotubes are oxidized and purified, and then acid-etched to increase the specific surface area and pore volume of the nanotubes; after being dispersed in deionized water, a neutralizing agent is added for hydroxylation modification; by adding an amination auxiliary agent and adjusting the pH, an amination halloysite nanotube is obtained; a circulating negative pressure method is used to allow the essential oil to enter the lumen of the amination halloysite nanotube; finally, kaolin and other composite preparations are added in proportion. The antibacterial sustained-release tablet of essential oil loaded on halloysite nanotubes can be widely used in agriculture to prevent and control plant root rot, food processing to extend the shelf life, medical equipment disinfection to improve safety, and indoor air purification to remove harmful microorganisms, thereby achieving long-term antibacterial and health protection in multiple fields.
[0019] Example 1 A method for preparing a composite halloysite nanotube essential oil sustained-release tablet with long-lasting antibacterial performance comprises the following steps: Step 1: Take 15 g of halloysite nanotubes (HNTs) and disperse them in 150 mL 30% H2O2. Stir at 340 r for 1 h at room temperature. Centrifuge at 10000 r / min to obtain a solid purified sample. Blast dry at 110 °C for 3 h and vacuum dry at 60 °C for 2 h. High temperature can remove adsorbed water and crystal water on the surface of HNTs and improve drying efficiency. In a vacuum environment at 60 °C, while ensuring effective evaporation of the solvent, the solvent can be prevented from entering the vacuum pump and causing cold well overload, thus achieving rapid drying at low temperature. Excessive temperature may cause the material to be over-dried, thus affecting its quality and performance. The temperature setting of 60 °C can ensure that the material is fully dried while avoiding the negative effects of over-drying.
[0020] Step 2: Take 8 g of purified halloysite nanotubes obtained in step 1 and disperse them in 500 mL of 10% (w / w) nitric acid solution, stir at 70°C for 24 h to obtain acidified halloysite nanotubes; the process conditions for treating the halloysite nanotubes with a 10% (w / w) nitric acid solution are relatively mild and easy to control and operate. The 10% (w / w) nitric acid treatment can activate the surface of the halloysite nanotubes, produce more active sites on the surface, and is conducive to subsequent chemical reactions and modification treatments.
[0021] Step 3: Take 6 g of acidified halloysite nanotubes and disperse them in 200 mL of deionized water. Take excess ammonia water and heat them. Pass ammonia gas into the halloysite nanotube suspension through condensation reflux. Add 3 drops of modifier 3-aminopropyltriethoxysilane. Centrifuge at 10000 r / min for 10 min and wash with water 3 times until pH is 7. Dry at 120℃ for 6.5 h and vacuum dry at 60℃ for 2 h to obtain ammoniated halloysite nanotubes containing ammonium nitrate crystals inside. Ammonia water, as an alkaline solution, can provide abundant amino groups (-NH2) to react with the Al-OH active sites on the surface of the halloysite nanotubes to form an amination product. Heating can accelerate molecular motion, promote contact and collision between reactants, and thus increase the reaction rate.
[0022] Step 4: Take the amino-modified halloysite nanotubes prepared in step 3, mix them with clove essential oil in a certain proportion, and ultrasonically treat them at 160 W power for 30 min in an ice bath (IMS-50 fully automatic snowflake ice maker). Then, place them in a vacuum drying oven (DZF-6030A), maintain the pressure under vacuum conditions for 30 min, and then open the vacuum valve to allow the clove essential oil to enter the HNTs lumen. Repeat 3-5 times, centrifuge and wash the surface clove essential oil with anhydrous ethanol, freeze-dry for 36 h, and obtain halloysite nanotube antibacterial nanoparticles loaded with clove essential oil (CEO@HNTs-NH2 antibacterial nanoparticles); the vacuum negative pressure forms a pressure difference inside and outside the HNTs tube, which can improve the loading efficiency of HNTs for clove essential oil.
[0023] The vacuum condition is a pressure of 0.1-1.0 MPa, and the centrifugation is 10000 r / min for 10 min.
[0024] The ratio of the aminated halloysite nanotubes to clove essential oil is 0.2 g / mL.
[0025] Step 5, the CEO@HNTs-NH2 antibacterial nanoparticles prepared in step 4 are mixed with kaolin and attapulgite in a certain proportion, and a tablet press is used to obtain an antibacterial sustained-release tablet using halloysite nanotubes as a carrier to load clove essential oil; After testing, the loading efficiency of the antibacterial sustained-release tablets prepared by using halloysite nanotubes as carriers to load clove essential oil was 2.93 g / g.
[0026] In step 5, the compounding ratio of CEO@HNTs-NH2 antibacterial nanoparticles to attapulgite is 3 / 2, the ratio of attapulgite to kaolin is 1 / 2-1 / 1, and the pressure of the tablet press is 0.4-0.6 MPa.
[0027] Example 2 A method for preparing a composite halloysite nanotube essential oil sustained-release tablet with long-lasting antibacterial performance comprises the following steps: Step 1: Take 15 g of halloysite nanotubes (HNTs) and disperse them in 150 mL 30% H2O2. Stir at 340 r for 1 h at room temperature. Centrifuge at 10000 r / min to obtain a solid purified sample. Blast dry at 110 °C for 3 h and vacuum dry at 60 °C for 2 h. High temperature can remove adsorbed water and crystal water on the surface of HNTs and improve drying efficiency. In a vacuum environment at 60 °C, while ensuring effective evaporation of the solvent, the solvent can be prevented from entering the vacuum pump and causing cold well overload, thus achieving rapid drying at low temperature. Excessive temperature may cause the material to be over-dried, thus affecting its quality and performance. The temperature setting of 60 °C can ensure that the material is fully dried while avoiding the negative effects of over-drying.
[0028] Step 2: Take 8 g of purified halloysite nanotubes obtained in step 1 and disperse them in 500 mL of 10% (w / w) nitric acid solution, stir at 70°C for 24 h to obtain acidified halloysite nanotubes; use 10% (w / w) nitric acid solution to treat halloysite nanotubes, the process conditions are relatively mild, easy to control and operate. Nitric acid treatment can activate the surface of halloysite nanotubes, so that more active sites are generated on the surface, which is conducive to subsequent chemical reactions and modification treatments.
[0029] Step 3: Take 6 g of acidified halloysite nanotubes and disperse them in 200 ml of deionized water, take excess ammonia water and heat them, pass ammonia gas into the halloysite nanotube suspension through condensation reflux, add 5 drops of modifier 3-aminopropyltriethoxysilane, centrifuge at 10000 r / min for 10 min, wash with water 3 times until pH is 7, dry at 120℃ for 6.5 h, and vacuum dry at 60℃ for 2 h to obtain the aminated halloysite nanotubes containing ammonium nitrate crystals inside; ammonia water, as an alkaline solution, can provide abundant amino groups (-NH2), react with the Al-OH active sites on the surface of the halloysite nanotubes to form an amination product. Heating can accelerate molecular motion, promote contact and collision between reactants, and thus increase the reaction rate.
[0030] Step 4: Take the amino-modified halloysite nanotubes prepared in step 3, mix them with clove essential oil in a certain proportion, and ultrasonically treat them at 160 W power for 30 min in an ice bath (IMS-50 fully automatic snowflake ice maker). Then, place them in a vacuum drying oven (DZF-6030A), maintain the pressure under vacuum conditions for 30 min, and then open the vacuum valve to allow the clove essential oil to enter the HNTs lumen. Repeat 3-5 times, centrifuge and wash the surface clove essential oil with anhydrous ethanol, freeze-dry for 36 h, and obtain halloysite nanotube antibacterial nanoparticles loaded with clove essential oil (CEO@HNTs-NH2 antibacterial nanoparticles); the vacuum negative pressure forms a pressure difference inside and outside the HNTs tube, which can improve the loading efficiency of HNTs for clove essential oil.
[0031] The vacuum condition is a pressure of 0.1-1.0 MPa, and the centrifugation is 10000 r / min for 10 min.
[0032] The ratio of the amino-modified halloysite nanotubes to clove essential oil is 0.1 g / mL.
[0033] Step 5, the CEO@HNTs-NH2 antibacterial nanoparticles prepared in step 4 are mixed with kaolin and attapulgite in a certain proportion, and a tablet press is used to obtain an antibacterial sustained-release tablet using halloysite nanotubes as a carrier to load clove essential oil; After testing, the loading efficiency of the antibacterial sustained-release tablets prepared by using halloysite nanotubes as carriers to load clove essential oil was 3.58 g / g.
[0034] In step 5, the compounding ratio of CEO@HNTs-NH2 antibacterial nanoparticles to attapulgite is 3 / 2, the ratio of attapulgite to kaolin is 1 / 2-1 / 1, and the pressure of the tablet press is 0.4-0.6 MPa.
[0035] Example 3 A method for preparing a composite halloysite nanotube essential oil sustained-release tablet with long-lasting antibacterial performance comprises the following steps: Step 1: Take 15 g of halloysite nanotubes (HNTs) and disperse them in 150 mL 30% H2O2. Stir at 340 r for 1 h at room temperature. Centrifuge at 10000 r / min to obtain a solid purified sample. Blast dry at 110 °C for 3 h and vacuum dry at 60 °C for 2 h. High temperature can remove adsorbed water and crystal water on the surface of HNTs and improve drying efficiency. In a vacuum environment at 60 °C, while ensuring effective evaporation of the solvent, the solvent can be prevented from entering the vacuum pump and causing cold well overload, thus achieving rapid drying at low temperature. Excessive temperature may cause the material to be over-dried, thus affecting its quality and performance. The temperature setting of 60 °C can ensure that the material is fully dried while avoiding the negative effects of over-drying.
[0036] Step 2: Take 8 g of purified halloysite nanotubes obtained in step 1 and disperse them in 500 mL of 10% (w / w) nitric acid solution, stir at 70°C for 24 h to obtain acidified halloysite nanotubes; use 10% (w / w) nitric acid solution to treat halloysite nanotubes, the process conditions are relatively mild, easy to control and operate. Nitric acid treatment can activate the surface of halloysite nanotubes, so that more active sites are generated on the surface, which is conducive to subsequent chemical reactions and modification treatments.
[0037] Step 3: Take 6 g of acidified halloysite nanotubes and disperse them in 200 mL of deionized water. Take excess ammonia water and heat them. Pass ammonia gas into the halloysite nanotube suspension through condensation reflux. Add 10 drops of modifier 3-aminopropyltriethoxysilane. Centrifuge at 10000 r / min for 10 min and wash with water three times until the pH is 7. Dry at 120℃ for 6.5 h and vacuum dry at 60℃ for 2 h to obtain the aminated halloysite nanotubes containing ammonium nitrate crystals inside. Ammonia water, as an alkaline solution, can provide abundant amino groups (-NH2) to react with the Al-OH active sites on the surface of the halloysite nanotubes to form an amination product. Heating can accelerate molecular motion, promote contact and collision between reactants, and thus increase the reaction rate.
[0038] Step 4: Take the amino-modified halloysite nanotubes prepared in step 3, mix them with clove essential oil in a certain proportion, and ultrasonically treat them at 160 W power for 30 min in an ice bath (IMS-50 fully automatic snowflake ice maker). Then, place them in a vacuum drying oven (DZF-6030A), maintain the pressure under vacuum conditions for 30 min, and then open the vacuum valve to allow the clove essential oil to enter the HNTs lumen. Repeat 3-5 times, centrifuge and wash the surface clove essential oil with anhydrous ethanol, freeze-dry for 36 h, and obtain halloysite nanotube antibacterial nanoparticles loaded with clove essential oil (CEO@HNTs-NH2 antibacterial nanoparticles); the vacuum negative pressure forms a pressure difference inside and outside the HNTs tube, which can improve the loading efficiency of HNTs for clove essential oil.
[0039] The vacuum condition is a pressure of 0.1-1.0 MPa, and the centrifugation is 10000 r / min for 10 min.
[0040] The ratio of the amino-modified halloysite nanotubes to clove essential oil is 0.07 g / mL.
[0041] Step 5, the CEO@HNTs-NH2 antibacterial nanoparticles prepared in step 4 are mixed with kaolin and attapulgite in a certain proportion, and a tablet press is used to obtain an antibacterial sustained-release tablet using halloysite nanotubes as a carrier to load clove essential oil; After testing, the loading efficiency of the antibacterial sustained-release tablets prepared by using halloysite nanotubes as carriers to load clove essential oil was 3.4 g / g.
[0042] In step 5, the compounding ratio of CEO@HNTs-NH2 antibacterial nanoparticles to attapulgite is 3 / 2, the ratio of attapulgite to kaolin is 1 / 2-1 / 1, and the pressure of the tablet press is 0.4-0.6 MPa.
[0043] Example 4 A method for preparing a composite halloysite nanotube essential oil sustained-release tablet with long-lasting antibacterial performance comprises the following steps: Step 1: Take 15 g of halloysite nanotubes (HNTs) and disperse them in 150 mL 30% H2O2. Stir at 340 r for 1 h at room temperature. Centrifuge at 10000 r / min to obtain a solid purified sample. Blast dry at 110 °C for 3 h and vacuum dry at 60 °C for 2 h. High temperature can remove adsorbed water and crystal water on the surface of HNTs and improve drying efficiency. In a vacuum environment at 60 °C, while ensuring effective evaporation of the solvent, the solvent can be prevented from entering the vacuum pump and causing cold well overload, thus achieving rapid drying at low temperature. Excessive temperature may cause the material to be over-dried, thus affecting its quality and performance. The temperature setting of 60 °C can ensure that the material is fully dried while avoiding the negative effects of over-drying.
[0044] Step 2: Take 8 g of purified halloysite nanotubes prepared in step 1 and disperse them in 500 mL of 10% (w / w) nitric acid solution, stir at 70°C for 24 h to obtain acidified halloysite nanotubes; use 10% (w / w) nitric acid solution to treat halloysite nanotubes, the process conditions are relatively mild, easy to control and operate. Nitric acid treatment can activate the surface of halloysite nanotubes, so that more active sites are generated on the surface, which is conducive to subsequent chemical reactions and modification treatments.
[0045] Step 3: Take 6 g of acidified halloysite nanotubes and disperse them in 200 mL of deionized water. Take excess ammonia water and heat them. Pass ammonia gas into the halloysite nanotube suspension through condensation reflux. Add 12 drops of modifier 3-aminopropyltriethoxysilane. Centrifuge at 10000 r / min for 10 min and wash with water three times until the pH is 7. Dry at 120℃ for 6.5 h and vacuum dry at 60℃ for 2 h to obtain the aminated halloysite nanotubes containing ammonium nitrate crystals inside. Ammonia water, as an alkaline solution, can provide abundant amino groups (-NH2) to react with the Al-OH active sites on the surface of the halloysite nanotubes to form an amination product. Heating can accelerate molecular motion, promote contact and collision between reactants, and thus increase the reaction rate.
[0046] Step 4: Take the amino-modified halloysite nanotubes prepared in step 3, mix them with clove essential oil in a certain proportion, and ultrasonically treat them at 160 W power for 30 min in an ice bath (IMS-50 fully automatic snowflake ice maker). Then, place them in a vacuum drying oven (DZF-6030A), maintain the pressure under vacuum conditions for 30 min, and then open the vacuum valve to allow the clove essential oil to enter the HNTs lumen. Repeat 3-5 times, centrifuge, and wash the surface clove essential oil with anhydrous ethanol to obtain halloysite nanotube antibacterial nanoparticles loaded with clove essential oil (CEO@HNTs-NH2 antibacterial nanoparticles); the vacuum negative pressure forms a pressure difference inside and outside the HNTs tube, which can improve the loading efficiency of HNTs for clove essential oil.
[0047] The vacuum condition is a pressure of 0.1-1.0 MPa, and the centrifugation is 10000 r / min for 10 min.
[0048] The ratio of the amino-modified halloysite nanotubes to clove essential oil is 0.05 g / mL.
[0049] Step 5, the CEO@HNTs-NH2 antibacterial nanoparticles prepared in step 4 are mixed with kaolin and attapulgite in a certain proportion, and a tablet press is used to obtain an antibacterial sustained-release tablet using halloysite nanotubes as a carrier to load clove essential oil; After testing, the loading efficiency of the antibacterial sustained-release tablets prepared by using halloysite nanotubes as carriers to load clove essential oil was 3.38 g / g.
[0050] In step 5, the compounding ratio of CEO@HNTs-NH2 antibacterial nanoparticles to attapulgite is 3 / 2, the ratio of attapulgite to kaolin is 1 / 2-1 / 1, and the pressure of the tablet press is 0.4-0.6 MPa.
[0051] The antibacterial sustained-release tablets prepared in Example 2 using halloysite nanotubes as carriers to load clove essential oil are used as samples, and the structural properties of the nano antibacterial sustained-release composite material prepared by the present invention are analyzed and explained by means of Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG), scanning electron microscopy (SEM) and performance testing.
[0052] 1. FTIR analysis Figure 1 The FTIR images show the functional groups and chemical bond structures of acidified, hydroxylated, and amino-treated halloysite nanotubes and the antibacterial nanoparticle composite material loaded with clove essential oil using halloysite nanotubes as carriers. The characteristic peaks of acidified halloysite nanotubes have five obvious characteristic peaks, namely, 3500 cm -1 OH stretching vibration near 1600 cm -1 OH deformation stretching vibration at 1048 cm -1 In-plane Si-O stretching vibration at 792 cm -1 Si-O vertical stretching vibration at 550 cm -1 The Al-O-Si deformation vibration at 3697.27 cm in the spectrum of aminated halloysite nanotubes -1 and 3623.01cm -1 The peak at 1632.69 cm-1 is attributed to the symmetric stretching vibration of the hydroxyl groups on the inner surface of the halloysite nanotubes. -1 The absorption peak at belongs to the bending vibration of the hydroxyl group of water adsorbed in the halloysite nanotubes. The spectrum of the loaded material shows not only the characteristic spectrum of halloysite nanotubes, but also the characteristic spectrum of clove essential oil, indicating that clove essential oil has been successfully encapsulated in the halloysite nanotubes.
[0053] 2.TG analysis Figure 2The TG graph shows the relationship between the mass change of essential oil, halloysite nanotubes and the antibacterial nanoparticle composite material loaded with clove essential oil using halloysite nanotubes as carriers and temperature. The mass loss in the initial heating stage before 100°C is attributed to the physical volatilization of interlayer water or crystal water, the second mass loss stage is related to the thermal decomposition of clove essential oil, and the final mass loss stage can be attributed to the thermal degradation of hydroxyl groups on the halloysite nanotubes. The mass loss of clove essential oil not encapsulated in halloysite nanotubes occurs in the range of 50-200°C, and the mass loss of clove essential oil loaded into halloysite nanotubes is in the range of 200-400°C. Compared with the free clove essential oil, the thermal stability of clove essential oil loaded into the inner cavity of halloysite nanotubes is significantly improved, indicating that the antibacterial sustained-release tablets loaded with clove essential oil using halloysite nanotubes as carriers prepared by the present invention have a long-lasting release effect.
[0054] 3. SEM analysis Figure 3 Composite materials of halloysite nanotubes after purification, modification and loading used in this study are shown, where the purified halloysite nanotubes show a typical tubular structure with a smooth surface. The modification treatment leads to a significant change in the morphology of HNTs, which show a rough surface with rough edges on the outer wall. After the clove essential oil is successfully loaded, the rough and fluffy structure disappears, and an oily substance appears on the surface, indicating that the clove essential oil is filled in the internal channels and pores of the halloysite nanotubes at atmospheric pressure.
[0055] 4. Analysis of essential oil loading effect Figure 4 The line graph shows the effect of negative pressure on the loading rate of clove essential oil on halloysite nanotubes before and after modification. As the negative pressure increases, the loading rates of both materials show a trend of first increasing and then decreasing, indicating that the loading rate of clove essential oil on the modified material can be increased under a certain negative pressure. The increase in negative pressure helps more clove essential oil molecules to be adsorbed or penetrated into the interior of the halloysite nanotubes in the early stage. When the negative pressure increases to a certain level, due to the limitation of the nanotube structure and the interaction between clove essential oil molecules, further loading becomes difficult, and the loading rate decreases.
[0056] Figure 5 A schematic diagram shows the compounding of three different clays, with kaolin as the coating material, and halloysite nanotubes and attapulgite as the core for composite tableting. On the premise that the halloysite nanotubes can load essential oils, due to the gaps and spaces between the attapulgite and the attapulgite, between the halloysite nanotubes and the attapulgite, and between the halloysite nanotubes and the halloysite nanotubes, the loading efficiency of the composite material can be further improved, making its antibacterial sustained-release time longer and the effect more significant.
[0057] Figure 6The sustained release characteristics of the antibacterial nanoparticle composite material under different pressures are shown. It can be seen that the sustained release characteristics of the composite material are optimal at 0.5 MPa, and the cumulative release rate of the composite material at 0.1 MPa pressure reaches 36.2%, while the cumulative release rate of 0.5 MPa after 7 days does not exceed 12%. The experimental results show that the volatilization rate can be effectively slowed down at 0.5 MPa, which may be because the optimal properties of the material can be maintained at the optimal pressure, making the spatial structure of clove essential oil and halloysite nanotubes more restrictive during the release process, further delaying the release rate of clove essential oil.
[0058] 5. Performance Analysis The tablets were prepared by compounding three different clays. Different compounding ratios were used and tableting was performed with the optimal pressure to obtain Figure 7 When the ratio of CEO@HNTs-NH2 antibacterial nanoparticles to attapulgite is 3 / 2, and the ratio of attapulgite to kaolin is 1 / 2-1 / 1, the size is stable and the sustained release effect is optimal. The composite material was formulated into a drug-based culture medium for antibacterial experiments. Figure 8 It can be seen that the prepared composite material has good antibacterial properties. After the antibacterial sustained-release tablet is buried in the soil environment, clove essential oil can be continuously released to achieve an antibacterial effect. During transportation, the tablet has dimensional stability, which is more convenient to transport and store than traditional liquid antibacterial agents and powdered antibacterial agents, making the product prepared by the present invention more advantageous.
Claims
1. A composite halloysite nanotube essential oil sustained-release tablet with long-lasting antibacterial performance, characterized in that The invention comprises antibacterial nanoparticles, kaolin and attapulgite. After the antibacterial nanoparticles and clove essential oil are mixed, the antibacterial nanoparticles are compounded with kaolin and attapulgite, and a tablet press is used to obtain antibacterial sustained-release tablets of clove essential oil loaded with halloysite nanotubes.
2. A method for preparing a composite halloysite nanotube essential oil sustained-release tablet with long-acting antibacterial performance according to claim 1, characterized in that: The following steps are involved: Step 1: Disperse 15 g of halloysite nanotubes HNTs in 150 mL of 20-30% H2O2, stir at 340 r for 1 h at room temperature, centrifuge at 10000 r / min to obtain a solid purified sample, dry it at 110 °C for 3 h, and vacuum dry it at 60 °C for 2 h. Step 2: Disperse 8-12 g of the purified halloysite nanotubes obtained in step 1 in 500 mL of a 10% nitric acid solution, and stir at 70° C. for 24-36 h to obtain acidified halloysite nanotubes; treat the halloysite nanotubes with a 10% nitric acid solution; Step 3, take 6-10 g of acidified halloysite nanotubes and disperse them in 200-300 mL of deionized water to form a halloysite nanotube suspension, take excess ammonia water and heat it, pass ammonia gas into the halloysite nanotube suspension through condensation reflux, add 3-12 drops of modifier 3-aminopropyltriethoxysilane, centrifuge at 10000 r / min for 10 min and wash with water three times until the pH is 7, dry with air at 120°C for 6.5 h, and vacuum dry at 60°C for 2 h to obtain amination of halloysite nanotubes HNTs-NH2 containing ammonium nitrate crystals inside; Step 4: Take the aminated halloysite nanotubes prepared in step 3, mix the aminated halloysite nanotubes with clove essential oil, and ultrasonically treat them at a power of 160-200 W for 20-30 min in an ice bath environment at 0-4°C, place them in a vacuum drying oven, and maintain the pressure under vacuum conditions for 20-30 min; open the vacuum valve to allow the clove essential oil to enter the lumen of the halloysite nanotubes; repeat the above steps 3-5 times, centrifuge and wash the surface clove essential oil with anhydrous ethanol, and freeze-dry for 36 h to obtain halloysite nanotube antibacterial nanoparticles CEO@HNTs-NH2 loaded with clove essential oil; Step 5: Mix the antibacterial nanoparticles CEO@HNTs-NH2 prepared in step 4 with kaolin and attapulgite, and use a tablet press to press the antibacterial sustained-release tablets of halloysite nanotubes loaded with clove essential oil at a pressure of 0.4-0.6 KPa.
3. A method for preparing a composite halloysite nanotube essential oil sustained-release tablet with long-acting antibacterial performance according to claim 2, characterized in that: In the step 4, the mixing ratio of the aminated halloysite nanotubes and the clove essential oil is 0.05-0.2 g / mL.
4. A method for preparing a composite halloysite nanotube essential oil sustained-release tablet with long-acting antibacterial performance according to claim 2 or 3, characterized in that: The vacuum condition in step 4 is a pressure of 0.1-1.0 MPa, and the centrifugal condition is 10000 r / min for 10 min.
5. A method for preparing a composite halloysite nanotube essential oil sustained-release tablet with long-acting antibacterial performance according to claim 2, characterized in that: In the step 5, the mass ratio of CEO@HNTs-NH2 antibacterial nanoparticles to attapulgite is 3 / 2, and the mass ratio of attapulgite to kaolin is 1 / 2-1 / 1.
6. A method for preparing a composite halloysite nanotube essential oil sustained-release tablet with long-acting antibacterial performance according to claim 5, characterized in that: The pressure of the tablet press described in step 5 is 0.4-0.6 MPa.
7. A method for preparing a composite halloysite nanotube essential oil sustained-release tablet with long-acting antibacterial performance according to claim 4, characterized in that: In the step 4, the mixture is placed in a vacuum drying oven DZF-6030A in an ice bath at 0-4°C under the environment of an IMS-50 fully automatic flake ice maker.