Citronella lemongrass essential oil microcapsule, preparation method thereof, bacteriostatic agent and application

Abstract

The invention belongs to the technical field of bacteriostatic agents, and particularly relates to lemongrass essential oil microcapsules, a preparation method thereof, a bacteriostatic agent and application. The preparation method comprises the following steps: by taking lemongrass essential oil as a core material and Arabic gum and beta-cyclodextrin as wall materials, mixing the lemongrass essential oil, the Arabic gum and the beta-cyclodextrin, and preparing the lemongrass essential oil micro-capsule by adopting a spray drying method; the mass ratio of the Arabic gum to the beta-cyclodextrin is (0.5-2): 1, and the mass ratio of the total amount of the Arabic gum and the beta-cyclodextrin to the lemongrass essential oil is (4-6): 1. And then mixing the lemongrass essential oil microcapsules with starch and ethanol, granulating and drying to obtain the antibacterial patch. The lemongrass essential oil microcapsule disclosed by the invention is stable in quality, the action time of the lemongrass essential oil is prolonged, the purpose of long-acting bacteriostasis is achieved, and the technical defect of short action time of a lemongrass essential oil antibacterial agent in the prior art is overcome.

Description

Technical Field

[0001] The invention belongs to the technical field of antibacterial agents, and particularly relates to lemongrass essential oil microcapsules and a preparation method thereof, an antibacterial agent and an application thereof. Background Art

[0002] With the improvement of people's living standards, especially in recent years, people's demand for vehicle-mounted antibacterial agents has been increasing, and different types and dosage forms of antibacterial agents have been constantly innovated, such as vehicle-mounted antibacterial and odor-free ointment, vehicle-mounted aromatherapy, antibacterial tablets or antibacterial sprays. However, at present, the effective antibacterial ingredients in most antibacterial agents are chemically synthesized, which are not only complex in composition, but also contain more volatile organic compounds, which pollute the environment and harm human health. In comparison, a few antibacterial agents with natural plant essential oils as the main ingredients have been welcomed because they are more friendly to the environment and the human body.

[0003] Lemongrass essential oil is a volatile oily substance with a pleasant smell extracted from different parts of aromatic plants. In recent years, lemongrass essential oil antibacterial agents prepared by existing technical methods have shown the advantage of good antibacterial effect, but lemongrass essential oil antibacterial agents have the problem of short antibacterial time and unstable properties due to volatility, which affects the application of lemongrass essential oil antibacterial agents. Summary of the invention

[0004] In view of the deficiencies in the above-mentioned prior art, the present invention provides lemongrass essential oil microcapsules and a preparation method thereof, an antibacterial agent and application thereof. The present invention uses lemongrass essential oil as a core material, gum arabic and beta-cyclodextrin as wall materials, and adopts a spray drying method to prepare the lemongrass essential oil microcapsules. The lemongrass essential oil microcapsules of the present invention have stable quality, extend the action time of the lemongrass essential oil, achieve the purpose of long-term antibacterial effect, and overcome the technical defect of the lemongrass essential oil antibacterial agent in the prior art having a short action time.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] The preparation method of lemongrass essential oil microcapsules comprises the following steps:

[0007] After the aqueous solution of gum arabic and β-cyclodextrin are evenly mixed, polyethylene glycol and lemongrass essential oil are added, and the mixture is homogenized and emulsified. The lemongrass essential oil is used as the core material, the gum arabic and β-cyclodextrin are used as the wall materials, and the polyethylene glycol is used as the plasticizer and anti-adhesive agent. The polyethylene glycol prevents the lemongrass essential oil microcapsules from adhering to each other during spray drying, thereby obtaining an emulsion.

[0008] The mass ratio of gum arabic to beta-cyclodextrin is 0.5-2:1, and the mass ratio of the total amount of gum arabic and beta-cyclodextrin to lemongrass essential oil is 4-6:1.

[0009] The emulsion is spray-dried to obtain lemongrass essential oil microcapsules.

[0010] Preferably, the mass ratio of gum arabic to β-cyclodextrin is 2:1.

[0011] Preferably, the mass ratio of the total amount of gum arabic and β-cyclodextrin to lemongrass essential oil is 6:1.

[0012] Preferably, the homogenization time is 20 min-30 min.

[0013] Preferably, the spray drying temperature is 65°C-75°C.

[0014] The invention also protects the lemongrass essential oil microcapsules prepared by the preparation method.

[0015] The invention also protects an antibacterial agent prepared from the lemongrass essential oil microcapsule.

[0016] The present invention also protects the application of the antibacterial agent in the preparation of the antibacterial patch. The application method is: lemongrass essential oil microcapsules are mixed with starch and ethanol, and then granulated and dried to obtain lemongrass essential oil microcapsule particles. The lemongrass essential oil microcapsule particles are loaded into a bag body with an adhesive effect to obtain the antibacterial patch, and the adhesive is adhered to the outer side of the bag body.

[0017] Preferably, the volume percentage of ethanol is 70%-80%.

[0018] Preferably, the mass ratio of starch to lemongrass essential oil microcapsules is 20-40:100.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The present invention uses lemongrass essential oil as a core material, and uses gum arabic and β-cyclodextrin as wall materials. After the lemongrass essential oil, gum arabic and β-cyclodextrin are mixed, a spray drying method is adopted to prepare lemongrass essential oil microcapsules, wherein the mass ratio of gum arabic to β-cyclodextrin is 0.5-2:1, and the mass ratio of the total amount of gum arabic and β-cyclodextrin to the lemongrass essential oil is 4-6:1; and lemongrass essential oil microcapsules with a high embedding rate are obtained by adjusting the mass ratio of gum arabic to β-cyclodextrin and the mass ratio of the total amount of gum arabic and β-cyclodextrin to the lemongrass essential oil.

[0021] Lemongrass essential oil has an inhibitory effect on Escherichia coli, Aspergillus niger and Staphylococcus aureus, and the lemongrass essential oil has a fresh fragrance. Therefore, the present invention selects lemongrass essential oil as the core material for preparing lemongrass essential oil microcapsules.

[0022] As for the selection of wall materials, the present invention uses gum arabic and beta-cyclodextrin. Compared with other wall materials, gum arabic is the best natural gum in oil-in-water emulsions. It has good emulsification, film-forming properties and water solubility. In addition, changes in pH and temperature have almost no effect on its stability. However, due to its high cost, it is usually not the best choice as lemongrass essential oil microcapsules. Therefore, the present invention combines gum arabic with beta-cyclodextrin. The complex of beta-cyclodextrin and oil substances has high thermal stability and good storage stability, which gives new properties to lemongrass essential oil microcapsules while reducing costs.

[0023] The present invention selects spray drying method to prepare lemongrass essential oil microcapsules, which is simple to operate, easy to control, and does not use organic solvents, which is safe for human health and more suitable for industrial mass production. The spray drying method is to disperse the core material lemongrass essential oil in the wall material solution to form a suspension or an emulsion, and after atomization by an atomizer, the solvent in the droplets is rapidly volatilized by a hot air flow, so that the wall material is precipitated into capsules, and the lemongrass essential oil is coated in the wall material. When the spray drying method is used to prepare the lemongrass essential oil microcapsules, not only the content of the core material is increased, but also the wall material is conducive to the encapsulation of the core material, and the yield of the lemongrass essential oil microcapsules can also be increased.

[0024] 2. The experimental results show that the optimal process for preparing lemongrass essential oil microcapsules by spray drying is: the mass ratio of gum arabic: β-cyclodextrin is 2:1, the mass ratio of the total amount of gum arabic and β-cyclodextrin to lemongrass essential oil is 6:1, the homogenization time is 25 minutes, the spray drying temperature is 70°C, the lemongrass essential oil microcapsule embedding rate is 91.24%, and the drug loading amount is 10.05%.

[0025] The present invention also considers the problem that lemongrass essential oil is not portable due to its properties. Based on this, the present invention also prepares an antibacterial patch, specifically: after mixing lemongrass essential oil microcapsules with starch and ethanol, granulation and drying are performed to obtain lemongrass essential oil microcapsule particles, and the lemongrass essential oil microcapsule particles are loaded into a bag with an adhesive effect to obtain an antibacterial patch. Its preparation process parameters are: when the mass ratio of starch to lemongrass essential oil microcapsules is 20:100, the volume percentage of ethanol is 80%, and the drying temperature is 30°C, the antibacterial rate of the antibacterial patch is 94%, and the antibacterial time reaches 7d. Lemongrass essential oil is prepared into lemongrass essential oil microcapsules to improve its stability, extend the action time of lemongrass essential oil, is 2-5 times of the lemongrass essential oil antibacterial agent on the market, and achieves the purpose of long-term antibacterial, and the developed antibacterial patch is convenient to store, carry and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a graph showing the encapsulation efficiency of lemongrass essential oil microcapsules in Examples 11-13 and Comparative Examples 1-2.

[0027] Figure 2 It is a graph showing the encapsulation efficiency of lemongrass essential oil microcapsules in Example 11, Examples 14-15 and Comparative Examples 3-4.

[0028] Figure 3 It is a graph showing the encapsulation efficiency of lemongrass essential oil microcapsules in Example 11, Examples 16-17 and Comparative Examples 5-6.

[0029] Figure 4 It is a graph showing the encapsulation efficiency of lemongrass essential oil microcapsules in Example 11, Examples 18-19 and Comparative Examples 7-8.

[0030] Figure 5 The SEM images of the lemongrass essential oil microcapsules of Example 10 at different magnifications; wherein (a) is magnified 8000 times, and (b) is magnified 10000 times.

[0031] Figure 6 This is a physical picture of the antibacterial patch of Example 28.

[0032] Figure 7 This is a graph showing the long-term antibacterial test of the antibacterial patch of Example 28. DETAILED DESCRIPTION

[0033] The specific embodiments of the present invention are described in detail below, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention. The test methods described in the embodiments of the present invention are conventional methods unless otherwise specified.

[0034] The present invention adopts lemongrass essential oil microcapsule technology to increase the stability of the core lemongrass essential oil, so that the lemongrass essential oil is solidified, the shelf life is extended and the patch has the advantages of sustained and controlled release; the present invention also provides an antibacterial patch suitable for different areas, which uses lemongrass essential oil as a core material, adopts lemongrass essential oil microcapsule technology and patch preparation technology to prepare a long-acting antibacterial patch that can be used not only in vehicles but also in daily life and workspaces.

[0035] The technical solution of the present invention is further explained by using embodiments and comparative examples, as shown below:

[0036] Example 1

[0037] The preparation method of lemongrass essential oil microcapsules comprises the following steps:

[0038] S1. After mixing gum arabic and purified water, stir and dissolve them at 50°C with a magnetic stirrer for 30 minutes, then add β-cyclodextrin and continue to stir and dissolve for 20 minutes, then add PEG4000 and lemongrass essential oil and emulsify them with a homogenizer for 20 minutes to obtain an emulsion.

[0039] The mass ratio of gum arabic to β-cyclodextrin is 2:1, and the mass ratio of lemongrass essential oil to the total amount of gum arabic and β-cyclodextrin is 1:4.

[0040] S2. spray-drying the emulsion at a spray-drying temperature of 60° C. to obtain lemongrass essential oil microcapsules.

[0041] Example 2

[0042] The preparation method of lemongrass essential oil microcapsules comprises the following steps:

[0043] S1. After mixing gum arabic and purified water, stir and dissolve them at 50°C with a magnetic stirrer at high speed for 30 minutes, then add β-cyclodextrin and continue to stir and dissolve for 20 minutes, then add PEG4000 and lemongrass essential oil and emulsify them with a homogenizer for 25 minutes to obtain an emulsion.

[0044] The mass ratio of gum arabic to β-cyclodextrin is 2:1, and the mass ratio of lemongrass essential oil to the total amount of gum arabic and β-cyclodextrin is 1:5.

[0045] S2. spray-drying the emulsion at a spray-drying temperature of 65° C. to obtain lemongrass essential oil microcapsules.

[0046] Example 3

[0047] The preparation method of lemongrass essential oil microcapsules comprises the following steps:

[0048] S1. After mixing gum arabic and purified water, stir and dissolve them at 50°C with a magnetic stirrer for 30 minutes, then add β-cyclodextrin and continue to stir and dissolve for 20 minutes, then add PEG4000 and lemongrass essential oil and emulsify them with a homogenizer for 30 minutes to obtain an emulsion.

[0049] The mass ratio of gum arabic to β-cyclodextrin is 2:1, and the mass ratio of lemongrass essential oil to the total amount of gum arabic and β-cyclodextrin is 1:6.

[0050] S2. spray drying the emulsion at a spray drying temperature of 70° C. to obtain lemongrass essential oil microcapsules.

[0051] Example 4

[0052] The preparation method of lemongrass essential oil microcapsules comprises the following steps:

[0053] S1. After mixing gum arabic and purified water, stir and dissolve them at 50°C with a magnetic stirrer at high speed for 30 minutes, then add β-cyclodextrin and continue to stir and dissolve for 20 minutes, then add PEG4000 and lemongrass essential oil and emulsify them with a homogenizer for 25 minutes to obtain an emulsion.

[0054] The mass ratio of gum arabic to β-cyclodextrin is 1:2, and the mass ratio of lemongrass essential oil to the total amount of gum arabic and β-cyclodextrin is 1:4.

[0055] S2. spray drying the emulsion at a spray drying temperature of 70° C. to obtain lemongrass essential oil microcapsules.

[0056] Example 5

[0057] The preparation method of lemongrass essential oil microcapsules comprises the following steps:

[0058] S1. After mixing gum arabic and purified water, stir and dissolve them at 50°C with a magnetic stirrer for 30 minutes, then add β-cyclodextrin and continue to stir and dissolve for 20 minutes, then add PEG4000 and lemongrass essential oil and emulsify them with a homogenizer for 30 minutes to obtain an emulsion.

[0059] The mass ratio of gum arabic to β-cyclodextrin is 1:2, and the mass ratio of lemongrass essential oil to the total amount of gum arabic and β-cyclodextrin is 1:5.

[0060] S2. spray-drying the emulsion at a spray-drying temperature of 60° C. to obtain lemongrass essential oil microcapsules.

[0061] Example 6

[0062] The preparation method of lemongrass essential oil microcapsules comprises the following steps:

[0063] S1. After mixing gum arabic and purified water, stir and dissolve them at 50°C with a magnetic stirrer for 30 minutes, then add β-cyclodextrin and continue to stir and dissolve for 20 minutes, then add PEG4000 and lemongrass essential oil and emulsify them with a homogenizer for 20 minutes to obtain an emulsion.

[0064] The mass ratio of gum arabic to β-cyclodextrin is 1:2, and the mass ratio of lemongrass essential oil to the total amount of gum arabic and β-cyclodextrin is 1:6.

[0065] S2. spray-drying the emulsion at a spray-drying temperature of 65° C. to obtain lemongrass essential oil microcapsules.

[0066] Example 7

[0067] The preparation method of lemongrass essential oil microcapsules comprises the following steps:

[0068] S1. After mixing gum arabic and purified water, stir and dissolve them at 50°C with a magnetic stirrer for 30 minutes, then add β-cyclodextrin and continue to stir and dissolve for 20 minutes, then add PEG4000 and lemongrass essential oil and emulsify them with a homogenizer for 30 minutes to obtain an emulsion.

[0069] The mass ratio of gum arabic to β-cyclodextrin is 1:1, and the mass ratio of lemongrass essential oil to the total amount of gum arabic and β-cyclodextrin is 1:4.

[0070] S2. spray-drying the emulsion at a spray-drying temperature of 65° C. to obtain lemongrass essential oil microcapsules.

[0071] Example 8

[0072] The preparation method of lemongrass essential oil microcapsules comprises the following steps:

[0073] S1. After mixing gum arabic and purified water, stir and dissolve them at 50°C with a magnetic stirrer for 30 minutes, then add β-cyclodextrin and continue to stir and dissolve for 20 minutes, then add PEG4000 and lemongrass essential oil and emulsify them with a homogenizer for 20 minutes to obtain an emulsion.

[0074] The mass ratio of gum arabic to β-cyclodextrin is 1:1, and the mass ratio of lemongrass essential oil to the total amount of gum arabic and β-cyclodextrin is 1:5.

[0075] S2. spray drying the emulsion at a spray drying temperature of 70° C. to obtain lemongrass essential oil microcapsules.

[0076] Example 9

[0077] The preparation method of lemongrass essential oil microcapsules comprises the following steps:

[0078] S1. After mixing gum arabic and purified water, stir and dissolve them at 50°C with a magnetic stirrer at high speed for 30 minutes, then add β-cyclodextrin and continue to stir and dissolve for 20 minutes, then add PEG4000 and lemongrass essential oil and emulsify them with a homogenizer for 25 minutes to obtain an emulsion.

[0079] The mass ratio of gum arabic to β-cyclodextrin is 1:1, and the mass ratio of lemongrass essential oil to the total amount of gum arabic and β-cyclodextrin is 1:6.

[0080] S2. spray-drying the emulsion at a spray-drying temperature of 60° C. to obtain lemongrass essential oil microcapsules.

[0081] Example 10

[0082] The preparation method of lemongrass essential oil microcapsules comprises the following steps:

[0083] S1. After mixing gum arabic and purified water, stir and dissolve them at 50°C with a magnetic stirrer at high speed for 30 minutes, then add β-cyclodextrin and continue to stir and dissolve for 20 minutes, then add PEG4000 and lemongrass essential oil and emulsify them with a homogenizer for 25 minutes to obtain an emulsion.

[0084] The mass ratio of gum arabic to β-cyclodextrin is 2:1, and the mass ratio of lemongrass essential oil to the total amount of gum arabic and β-cyclodextrin is 1:6.

[0085] S2. spray drying the emulsion at a spray drying temperature of 70° C. to obtain lemongrass essential oil microcapsules.

[0086] The preparation of the antibacterial patch includes the following steps:

[0087] S3. Mix lemongrass essential oil microcapsules, starch and 70% ethanol, and then granulate them by wet method. Dry them in an oven at 30°C, granulate them after drying, add lubricant and mix them evenly, and install them to obtain an antibacterial patch; the amount of starch used is 20%.

[0088] Embodiment 11

[0089] The preparation method of lemongrass essential oil microcapsules comprises the following steps:

[0090] S1. After mixing gum arabic and purified water, stir and dissolve them at 50°C with a magnetic stirrer at high speed for 30 minutes, then add β-cyclodextrin and continue to stir and dissolve for 20 minutes, then add PEG4000 and lemongrass essential oil and emulsify them with a homogenizer for 25 minutes to obtain an emulsion.

[0091] The mass ratio of gum arabic to β-cyclodextrin is 1:1, and the mass ratio of lemongrass essential oil to the total amount of gum arabic and β-cyclodextrin is 1:5.

[0092] S2. spray-drying the emulsion at a spray-drying temperature of 65° C. to obtain lemongrass essential oil microcapsules.

[0093] The preparation of the antibacterial patch includes the following steps:

[0094] S3. Mix lemongrass essential oil microcapsules, starch and 80% ethanol, and then granulate them by wet method. Dry them in an oven at 30°C, granulate them after drying, add lubricant and mix them evenly, and install them to obtain an antibacterial patch; the amount of starch used is 20%.

[0095] Example 12

[0096] The preparation steps are the same as those of Example 11, except that the mass ratio of gum arabic to β-cyclodextrin is replaced from 1:1 to 2:1.

[0097] Embodiment 13

[0098] The preparation steps are the same as those of Example 11, except that the mass ratio of gum arabic to β-cyclodextrin is replaced from 1:1 to 1:2.

[0099] Embodiment 14

[0100] The preparation steps are the same as those of Example 11, except that the ratio of the mass of lemongrass essential oil to the total amount of gum arabic and β-cyclodextrin is changed from 1:5 to 1:4.

[0101] Embodiment 15

[0102] The preparation steps are the same as those of Example 11, except that the ratio of the mass of lemongrass essential oil to the total amount of gum arabic and β-cyclodextrin is changed from 1:5 to 1:6.

[0103] Example 16

[0104] The preparation steps are the same as those of Example 11, except that the homogenization time is replaced from 25 min to 20 min.

[0105] Embodiment 17

[0106] The preparation steps are the same as those of Example 11, except that the homogenization time is replaced from 25 min to 30 min.

[0107] Embodiment 18

[0108] The preparation steps are the same as those of Example 11, except that the spray drying temperature is replaced from 65°C to 60°C.

[0109] Embodiment 19

[0110] The preparation steps are the same as those of Example 11, except that the spray drying temperature is replaced from 65°C to 70°C.

[0111] Embodiment 20

[0112] The preparation steps are the same as those in Example 10, except that, in step S3, lemongrass essential oil microcapsules, starch and 75% ethanol are mixed, and then granulated by a wet method, and then dried in an oven at 35°C, granulated after drying, and finally a lubricant is added and mixed, and then mounted to obtain an antibacterial patch; wherein the amount of starch used is 20%.

[0113] Embodiment 21

[0114] The preparation steps are the same as those in Example 10, except that, in step S3, lemongrass essential oil microcapsules, starch and 80% ethanol are mixed, and then granulated by a wet method, and then dried in an oven at 40° C., granulated after drying, and finally a lubricant is added and mixed, and then mounted to obtain an antibacterial patch; wherein the amount of starch used is 20%.

[0115] Embodiment 22

[0116] The preparation steps are the same as those in Example 10, except that, in step S3, lemongrass essential oil microcapsules, starch and 70% ethanol are mixed, and then granulated by a wet method, and then dried in an oven at 35°C, granulated after drying, and finally a lubricant is added and mixed, and then mounted to obtain an antibacterial patch; wherein the amount of starch used is 30%.

[0117] Embodiment 23

[0118] The preparation steps are the same as those in Example 10, except that in step S3, lemongrass essential oil microcapsules, starch and 75% ethanol are mixed, and then granulated by a wet method, and then dried in an oven at 40°C, granulated after drying, and finally a lubricant is added and mixed, and then mounted to obtain an antibacterial patch; wherein the amount of starch used is 30%.

[0119] Embodiment 24

[0120] The preparation steps are the same as those in Example 10, except that, in step S3, lemongrass essential oil microcapsules, starch and 80% ethanol are mixed, and then granulated by a wet method, and then dried in an oven at 30°C, granulated after drying, and finally a lubricant is added and mixed, and then mounted to obtain an antibacterial patch; wherein the amount of starch used is 30%.

[0121] Embodiment 25

[0122] The preparation steps are the same as those in Example 10, except that, in step S3, lemongrass essential oil microcapsules, starch and 70% ethanol are mixed, and then granulated by a wet method, and then dried in an oven at 40°C, granulated after drying, and finally a lubricant is added and mixed, and then mounted to obtain an antibacterial patch; wherein the amount of starch used is 40%.

[0123] Embodiment 26

[0124] The preparation steps are the same as those in Example 10, except that in step S3, lemongrass essential oil microcapsules, starch and 75% ethanol are mixed, and then granulated by a wet method, and then dried in an oven at 30°C, granulated after drying, and finally a lubricant is added and mixed, and then mounted to obtain an antibacterial patch; wherein the amount of starch used is 40%.

[0125] Embodiment 27

[0126] The preparation steps are the same as those in Example 10, except that, in step S3, lemongrass essential oil microcapsules, starch and 80% ethanol are mixed, and then granulated by a wet method, and then dried in an oven at 35°C, granulated after drying, and finally a lubricant is added and mixed, and then mounted to obtain an antibacterial patch; wherein the amount of starch used is 40%.

[0127] Embodiment 28

[0128] The preparation steps are the same as those in Example 10, except that in step S3, lemongrass essential oil microcapsules, starch and 80% ethanol are mixed, and then granulated by a wet method, and then dried in an oven at 30°C, granulated after drying, and finally a lubricant is added and mixed, and then mounted to obtain an antibacterial patch, wherein the amount of starch used is 20%.

[0129] Comparative Example 1

[0130] The preparation steps are the same as those of Example 11, except that the mass ratio of gum arabic to β-cyclodextrin is replaced from 1:1 to 3:1.

[0131] Comparative Example 2

[0132] The preparation steps are the same as those of Example 11, except that the mass ratio of gum arabic to β-cyclodextrin is replaced from 1:1 to 1:3.

[0133] Comparative Example 3

[0134] The preparation steps are the same as those of Example 11, except that the ratio of the mass of lemongrass essential oil to the total amount of gum arabic and β-cyclodextrin is changed from 1:5 to 1:3.

[0135] Comparative Example 4

[0136] The preparation steps are the same as those of Example 11, except that the ratio of the mass of lemongrass essential oil to the total amount of gum arabic and β-cyclodextrin is changed from 1:5 to 1:7.

[0137] Comparative Example 5

[0138] The preparation steps are the same as those of Example 11, except that the homogenization time is replaced from 25 min to 15 min.

[0139] Comparative Example 6

[0140] The preparation steps are the same as those of Example 11, except that the homogenization time is replaced from 25 min to 35 min.

[0141] Comparative Example 7

[0142] The preparation steps are the same as those of Example 11, except that the spray drying temperature is replaced from 70°C to 75°C.

[0143] Comparative Example 8

[0144] The preparation steps are the same as those of Example 11, except that the spray drying temperature is replaced from 70°C to 80°C.

[0145] The following is a study using the lemongrass essential oil microcapsules of Examples 1-19 and Comparative Examples 1-8, and the antibacterial patches of Examples 10 and 20-28 as examples. The specific research methods and results are as follows:

[0146] 1. Single factor test of lemongrass essential oil microcapsules

[0147] 1.1 Determination of the embedding efficiency and drug loading rate of lemongrass essential oil microcapsules:

[0148] Weigh 0.01 g of lemongrass essential oil microcapsules and place them in a round-bottom flask, add water and zeolite and shake to dissolve, connect a volatile oil analyzer and a reflux condenser to the round-bottom flask, then place it in an electric heating mantle and heat to boiling, keep it at a slight boil for 5 hours, then let it stand for 1 hour, read the volatile oil content, and the reading is the total oil content of the lemongrass essential oil microcapsules.

[0149] Weigh 0.5g of lemongrass essential oil microcapsules accurately, rinse with anhydrous ethanol and dry in a vacuum dryer. Finally, weigh the dried lemongrass essential oil microcapsules. The difference between the two is the surface oil of the lemongrass essential oil microcapsules. The difference between the total oil content of the lemongrass essential oil microcapsules and the surface oil of the lemongrass essential oil microcapsules is the amount of drug encapsulated in the lemongrass essential oil microcapsule preparation. Then, the embedding rate is calculated using formula (1), and the drug loading is calculated using formula (2).

[0150]

[0151] 1.2 Single factor test conditions:

[0152] Single factor experiments were conducted on wall material ratio, core-wall ratio, homogenization time and spray drying temperature. Gum arabic and β-cyclodextrin were used as wall materials, lemongrass essential oil was used as core material, and the amount of polyethylene glycol 4000 was 2% of the total amount of gum arabic, β-cyclodextrin, polyethylene glycol and lemongrass essential oil. The wall material ratios of 3:1, 2:1, 1:1, 1:2 and 1:3 were investigated respectively; the core-wall ratios of 1:3, 1:4, 1:5, 1:6 and 1:7 were investigated respectively; the homogenization time and spray drying temperature were investigated respectively. The homogenization time was 15min, 20min, 25min, 30min and 35min; the spray drying temperature was 60℃, 65℃, 70℃, 75℃ and 80℃, and the influence of the above four factors on the embedding efficiency and drug loading of lemongrass essential oil microcapsules was investigated. The factor level table is shown in Table 1, where A is the wall material ratio (m:m), B is the core-wall ratio (m:m), C is the homogenization time (min), and D is the drying temperature (℃).

[0153] 1.3 Analysis of the preparation process of lemongrass essential oil microcapsules:

[0154] Depend on Figure 1 It can be seen that when the mass ratio of wall material gum arabic to β-cyclodextrin is 1:1, the embedding rate of lemongrass essential oil microcapsules of plant essential oil is the largest. As the wall material ratio increases, the embedding rate decreases, and the embedding rate decreases as the wall material ratio decreases. Therefore, the optimal wall material ratio is 1:1.

[0155] Depend on Figure 2 It can be seen that with the increase of the ratio of essential oil to wall material, the embedding rate of lemongrass essential oil microcapsules continues to increase. When the core material ratio reaches 1:5, the embedding rate is the largest, and then with the increase of the core material ratio, the embedding rate shows a downward trend. Therefore, the optimal core material ratio is 1:5.

[0156] Depend on Figure 3 It can be seen that when the homogenization time is too long or too short, the embedding rate will decrease, so the optimal homogenization time is 25 minutes.

[0157] Depend on Figure 4 It can be seen that when the spray drying temperature is between 60 and 65°C, the embedding rate of lemongrass essential oil microcapsules increases rapidly, and then decreases slowly with the increase of temperature, but the decline tends to be stable. At 65°C, the embedding rate of lemongrass essential oil microcapsules is the largest, so the optimal spray temperature is 65°C.

[0158] According to the above single factor test results, it can be seen that under each single factor test condition, when the wall material ratio is 1:1, the core wall ratio is 1:5, the homogenization time is 25min, and the spray temperature is 65℃, the encapsulation rate of lemongrass essential oil microcapsules reaches the highest.

[0159] 2. Orthogonal test of lemongrass essential oil microcapsules

[0160] 2.1 Results of orthogonal test of lemongrass essential oil microcapsules:

[0161] On the basis of the above single factor experiment, a four-factor three-level orthogonal optimization experiment was carried out. The factor level table is shown in Table 1, where A is the wall material ratio (m:m), B is the core wall ratio (m:m), C is the homogenization time (min), and D is the drying temperature (℃).

[0162] Table 1 Orthogonal test factors

[0163]

[0164] Table 2 Lemongrass essential oil microcapsule orthogonal test results

[0165]

[0166] When a is 0.05, the drying temperature (D) is used as the error, and variance analysis is performed. The results are shown in Table 3.

[0167] Table 3 Analysis of variance table

[0168] factor Sum of Squared Deviations Degrees of Freedom F-number P-value Significance Wall material ratio (A) 93.083 2 19.897 0.0478 Significant (P<0.05) Core to wall ratio (B) 127.227 2 27.196 0.0354 Significant (P<0.05) Homogenization time (C) 75.555 2 16.151 0.0583 Spray temperature (D) 4.678 2 1 0.5 error 4.68 2

[0169] From the orthogonal test results and variance analysis in Table 2 and Table 3, it can be seen that the horizontal factors A and B are significant, and the order of factors affecting the embedding rate of spray-dried lemongrass essential oil microcapsules is: core-wall ratio> wall material ratio> homogenization time> spray temperature (B>A>C>D). The best process combination obtained by the orthogonal test is A1B3C2D3, that is, when the ratio of gum arabic to β-cyclodextrin is 2:1, the ratio of core material to wall material is 1:6, the homogenization time is 25min, and the spray drying temperature is 70℃, it is the best preparation process for lemongrass essential oil microcapsules.

[0170] 2.2 Repeated validation test results:

[0171] According to the best process obtained by orthogonal experiment in Table 1, three parallel experiments were conducted to prepare samples 1, 2, and 3, and then the sample embedding rate was determined, as shown below:

[0172] Table 4 Repeated validation test results

[0173] Number of trials 1 2 3 Mean Embedding rate (%) 90.96 91.56 91.22 91.24 Drug loading (%) 11.20 10.75 11.20 10.05

[0174] Three parallel tests were carried out under the optimal process conditions obtained from the orthogonal test results (the ratio of gum arabic to β-cyclodextrin was 2:1, the ratio of core material to wall material was 1:6, the homogenization time was 25 min, and the spray drying temperature was 70°C). The average embedding rate of lemongrass essential oil microcapsules was 91.24%, which was higher than any group in the orthogonal test. The average drug loading rate of lemongrass essential oil microcapsules was 10.05%.

[0175] 3. Investigation of the capsule shape of lemongrass essential oil microcapsules

[0176] The lemongrass essential oil microcapsules prepared under orthogonal test conditions and under optimal process conditions were evenly sprinkled on the conductive glue attached to the sample stage, and the excess powder was blown off, and then gold was sprayed. Finally, the morphology of the lemongrass essential oil microcapsules was observed with a scanning electron microscope and photographed. The results showed that the morphology of the lemongrass essential oil microcapsules obtained under the orthogonal results and under the optimal process conditions was very good. Figure 5 The lemongrass essential oil microcapsules prepared under the optimal process conditions shown above have a round appearance, a dense surface, a high encapsulation rate, and no adhesion under scanning electron microscope observation.

[0177] 4. Orthogonal test of antibacterial patch

[0178] 4.1 Preparation process of antibacterial patch:

[0179] According to the optimal preparation process of lemongrass essential oil microcapsules, a large number of preparations are carried out. According to the hygroscopicity and stability, the best auxiliary material starch is selected as the diluent, and ethanol is sprayed as the wetting agent. The microcapsules are made into balls that can be grasped by hand and dispersed when pressed. The microcapsules are extruded through a 20-mesh screen to form granules, dried in an oven, and granulated after drying. Finally, a lubricant is added, mixed, and mounted.

[0180] 4.2 Orthogonal Experimental Design

[0181] The lemongrass essential oil microcapsules prepared by the best preparation method of Example 10 were used as the main drug, and the preparation process of the antibacterial patch was optimized by orthogonal test. The main factors were starch dosage, volume percentage of ethanol, and drying temperature. On the basis of preliminary tests, the levels of each factor were determined, and the change in the number of air-deposited bacteria in the car was used as the evaluation standard to evaluate the effect of the antibacterial patch on the colony of the car. The factor level table is shown in Table 5, where A is the starch dosage (%), B is the volume percentage of ethanol (%), and C is the drying temperature (°C).

[0182] Table 5. Table of factors and levels of orthogonal test design for antibacterial patch

[0183]

[0184]

[0185] Determination of sedimentation bacteria in cars:

[0186] The method for determining the sedimentation bacteria was the classic method of Guo Huo. A soybean agar culture plate with a diameter of 9 cm was placed at each sampling point of the car, exposed to the air for 30 minutes, covered with a culture dish cover, and cultured in a 37°C biochemical incubator for 48 hours. The total number of colonies on the plate was observed and counted, which was the blank group. In addition, the antibacterial patch prepared according to the orthogonal test conditions was attached to the front and back of the car. After 24 hours, a soybean agar culture plate with a diameter of 9 cm was placed at each sampling point of the car, exposed to the air for 30 minutes, covered with a culture dish cover, and cultured in the same way as above. The total number of colonies on the plate was observed and counted, which was the test group. Finally, the antibacterial rate was calculated using formula (3) as the evaluation index.

[0187]

[0188] 4.3 Analysis of orthogonal test results

[0189] Table 6 Orthogonal test results

[0190]

[0191]

[0192] When a is 0.05, variance analysis is performed and the results are shown in Table 9.

[0193] Table 7 Variance analysis table

[0194] factor Sum of Squared Deviations Degrees of Freedom F-number P-value Significance Starch dosage (A) 307.891 2 28.793 0.034 Significant Volume percentage of ethanol (B) 19.058 2 1.782 0.359 Drying temperature (C) 204.287 2 19.105 0.049 Significant error 10.693 2

[0195] From the orthogonal test results and variance analysis in Tables 6 and 7, it can be seen that the horizontal factors A and C are significant, and the order of factors affecting the antibacterial effect of plant essential oil patches is: starch dosage> drying temperature> volume percentage of ethanol (A>C>B). The best process combination obtained by the orthogonal test is A1B3C1, that is, when the starch dosage is 20%, the volume percentage of ethanol is 80%, and the drying temperature is 30°C, it is the best preparation process for the antibacterial patch.

[0196] 4.4 Repeated validation test results

[0197] Three batches of samples were prepared according to the optimal preparation process conditions. The sedimentation bacteria were determined for each of the three batches of samples. The total number of colonies on the plates was observed and counted, and the inhibition rate was calculated.

[0198] Table 8 Repeated validation test results

[0199] Number of trials 1 2 3 Mean Antibacterial rate (%) 93.1 92.7 96.2 94.0

[0200] The results are shown in Table 8. The best process conditions (starch dosage of 20%, ethanol volume percentage of 80%, drying temperature of 30°C) obtained from the orthogonal test results were used to prepare antibacterial patches. Figure 6As shown, three parallel experiments were then carried out, and the average antibacterial rate of the antibacterial patch was 94.0%, which was higher than any group in the orthogonal test.

[0201] 4.5 Study on the long-term effectiveness of antibacterial patches:

[0202] The antibacterial patches prepared according to the optimal preparation process were attached to the front and back of the car, and the sedimentation bacteria in the car were measured for one week, and the colony situation on the plate was observed and recorded every day.

[0203] according to Figure 7 As shown in the figure, the antibacterial patch was placed in a car for a week and the colony was measured. It can be seen that the antibacterial patch still has a good antibacterial effect on the seventh day. In addition, the aroma of lemongrass essential oil can still be smelled one month after the antibacterial patch is prepared. This shows that the antibacterial patch can effectively inhibit bacterial growth for at least one week and has an antibacterial effect for at least one month.

[0204] The present invention obtains the optimal preparation process of lemongrass essential oil microcapsules through single factor test and orthogonal test, the mass ratio of gum arabic to β-cyclodextrin is 2:1, the mass ratio of core material to wall material is 1:6, the homogenization time is 25min, and the spray drying temperature is 70°C, which maximizes the embedding rate of lemongrass essential oil microcapsules; then the optimal preparation process of antibacterial patches is obtained through orthogonal test, the starch dosage is 20%, the volume percentage of ethanol is 80%, and the drying temperature is 30°C. And it is evaluated that the antibacterial patch has a good antibacterial effect in a car, and the antibacterial time is 2 to 5 times that of the essential oil patches available on the market. This antibacterial patch has a fresh smell, is small and light, is easy to carry, has a good antibacterial effect, and is an ideal car-mounted antibacterial patch. In addition, the antibacterial patch can also be used in different places such as wardrobes or shoe cabinets in life, not just in the car.

[0205] During the experiment, it was found that when the core-wall ratio was constant, the encapsulation rate of the drug loading was also large, but within a certain range, the drug loading rate of the core-wall ratio was lower than that of the core-wall ratio. It may be that when the wall material content was high, the viscosity of the gum arabic and β-cyclodextrin emulsions increased, and they could not be quickly atomized to form the outer wall of the lemongrass essential oil microcapsules, resulting in a decrease in the embedding rate. In addition, the stability of the mixed wall material emulsion prepared by lemongrass essential oil microcapsules was slightly poor, which may be due to the addition of anticoagulants during the emulsification process. In this experiment, spray drying was performed immediately after emulsification and the test dosage was small, which had little effect. However, further research is required in industrial production. In the preparation of the patch, this experiment only considered cost and hygroscopicity and selected starch as a diluent. There are many other diluents such as sugars, cellulose and inorganic salts to choose from. During the antibacterial test, because the uniformity of the car environment could not be guaranteed, it had more or less impact on the test results, resulting in unavoidable deviations in the test results. In addition, due to considerations of portability, the amount of antibacterial patches should not be too much, so the dosage of the patches can be changed according to actual conditions during use.

[0206] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these changes and variations. The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and their protection scope is not limited thereto. Equivalent substitutions or changes made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention, and the protection scope of the present invention shall be subject to the claims.

Claims

1. A method for preparing lemongrass essential oil microcapsules, characterized in that: The steps include: After the aqueous solution of gum arabic and β-cyclodextrin are uniformly mixed, polyethylene glycol and lemongrass essential oil are added, and the mixture is homogenized and emulsified to obtain an emulsion with lemongrass essential oil as the core material, gum arabic and β-cyclodextrin as the wall material, and polyethylene glycol as the plasticizer and anti-adhesive agent; The mass ratio of gum arabic to β-cyclodextrin is 0.5-2:1, and the mass ratio of the total amount of gum arabic and β-cyclodextrin to lemongrass essential oil is 4-6:1; The emulsion is spray-dried to obtain lemongrass essential oil microcapsules.

2. The method for preparing lemongrass essential oil microcapsules according to claim 1, characterized in that: The mass ratio of gum arabic to β-cyclodextrin is 2:

1.

3. The method for preparing lemongrass essential oil microcapsules according to claim 1, characterized in that: The mass ratio of the total amount of gum arabic and β-cyclodextrin to lemongrass essential oil is 6:

1.

4. The method for preparing lemongrass essential oil microcapsules according to claim 1, characterized in that: The homogenization time is 20min-30min.

5. The method for preparing lemongrass essential oil microcapsules according to claim 1, characterized in that: The spray drying temperature is 65°C-75°C.

6. Lemongrass essential oil microcapsules prepared by the preparation method according to any one of claims 1 to 5.

7. An antibacterial agent, characterized in that Prepared from the lemongrass essential oil microcapsule described in claim 6.

8. Use of the antibacterial agent according to claim 7 in the preparation of an antibacterial patch, characterized in that: The application method is as follows: lemongrass essential oil microcapsules are mixed with starch and ethanol, granulated and dried to obtain lemongrass essential oil microcapsule particles, and the lemongrass essential oil microcapsule particles are loaded into a bag with an adhesive effect to obtain an antibacterial patch.

9. The use according to claim 8, characterized in that: The volume percentage of ethanol is 70%-80%.

10. The use according to claim 8, characterized in that: The mass ratio of starch to lemongrass essential oil microcapsules is 20-40:100.

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