Antibacterial shower gel containing modified zinc oxide and preparation method thereof

Abstract

The invention belongs to the field of antibacterial care products, and particularly discloses antibacterial shower gel containing modified zinc oxide and a preparation method of the antibacterial shower gel. According to the shower gel, the trisodium citrate is used for assisting ultrasonic modification of zinc oxide, and the synergistic effect of the tea tree oil microcapsules and the lactobacillus fermentation filtrate is combined, so that the problems that a traditional antibacterial agent is easy to damage skin micro-ecology and is insufficient in drug resistance induction and biofilm resistance are solved; comprising the following components: modified zinc oxide, tea tree oil microcapsules, lactobacillus fermentation filtrate, cocamidopropyl betaine, sodium lauroyl sarcosinate, a pH regulator and deionized water. Wherein the modified zinc oxide is coated with chitosan and modified with trisodium citrate, so that the dispersity and the photoresponse controllability are remarkably improved; the tea tree oil microcapsule adopts a beta-cyclodextrin / Arabic gum composite wall material to realize slow release of active ingredients; lactobacillus fermentation filtrate contains antibacterial peptide and polysaccharide degrading enzyme, and synergistically destroys a biological membrane structure, so that the antibacterial liquid has the advantages of high-efficiency antibacterial property, mild nursing property and long-term stability.

Description

Technical Field

[0001] The invention belongs to the field of antibacterial care products and specifically discloses an antibacterial shower gel containing modified zinc oxide and a preparation method thereof. Background Art

[0002] With the improvement of public health awareness, personal care products with antibacterial functions have received widespread attention. Traditional antibacterial shower gels mostly use chemical synthetic antibacterial agents such as triclosan and benzalkonium chloride. Although these ingredients can effectively kill pathogenic bacteria, long-term use can easily destroy the balance of skin microecology and cause adverse reactions such as irritant contact dermatitis. More seriously, some broad-spectrum antibacterial agents can induce bacteria to produce drug-resistant genes, posing a risk of spreading environmental microbial resistance. The existing technology attempts to replace chemical antibacterial agents by adding inorganic antibacterial agents such as zinc oxide, but ordinary zinc oxide has problems such as easy agglomeration and sedimentation and uncontrollable photocatalytic activity. As a result, in actual applications, the added concentration needs to be increased to achieve the antibacterial effect, and excessive zinc oxide will aggravate the dryness and tightness of the skin, affecting the product usage experience.

[0003] Among existing patents, CN117412734A discloses an anti-biofilm preservative composition that inhibits biofilm formation through the synergistic action of organic acids and zinc compounds. However, the zinc compounds (such as zinc acetate and zinc gluconate) used in this patent are susceptible to charge neutralization reactions with anionic surfactants in shower gel systems, resulting in reduced system stability and a clearance rate of less than 60% for mature biofilms. Furthermore, existing antibacterial cleansing products generally lack the ability to remove pathogenic biofilms. Pathogenic bacteria such as Staphylococcus aureus significantly enhance their tolerance to antimicrobial ingredients by forming biofilms, making conventional surfactant systems difficult to disrupt the three-dimensional structure of biofilms. While previous studies have attempted to enhance the anti-biofilm effect by using complex organic acids or enzymes, these ingredients are easily inactivated in the alkaline shower gel system and have poor compatibility with anionic surfactants, which can lead to reduced product stability. Furthermore, zinc oxide-surfactant composite systems prepared using traditional processes often exhibit uneven particle size distribution, which can lead to the destruction of the micelle structure during storage, affecting the sustained-release performance of the antimicrobial ingredient. Therefore, developing an antibacterial shower gel that has high antibacterial properties, biofilm removal ability and a mild skin feel has become a technical problem that needs to be solved urgently in this field. Summary of the Invention

[0004] To address the above-mentioned technical problems, the present invention discloses an antibacterial shower gel containing modified zinc oxide and a preparation method thereof. The present invention utilizes trisodium citrate-assisted ultrasonic modification of zinc oxide (to optimize dispersibility and light-responsiveness), tea tree oil microcapsules, and lactobacillus fermentation filtrate to synergistically combat biofilms (breaking through the EPS barrier), ultimately achieving a technological breakthrough with an antibacterial rate ≥ 99.9% and a skin irritation score of < 0.3 points.

[0005] The present invention includes the following technical solutions: An antibacterial body wash containing modified zinc oxide, comprising the following components in parts by weight per 100 parts: Modified zinc oxide 3 - 8 parts Tea tree oil microcapsules 1 - 3 parts Lactobacillus fermentation filtrate 2 - 5 parts Asiaticoside 0.5 - 1.5 parts Cocamidopropyl betaine 15 - 25 parts Sodium lauroyl sarcosinate 5 - 10 parts Glycerol 3 - 8 parts Xanthan gum 0.1 - 0.5 part Disodium EDTA 0.05 - 0.1 part pH regulator appropriate amount to pH 5.5 - 6.5 Deionized water the balance; The preparation method of the modified zinc oxide is as follows: Disperse zinc oxide in a 1 - 3% chitosan acetate solution, add trisodium citrate, and the molar ratio of zinc oxide to trisodium citrate is 1:0.5 - 1.2. Perform ultrasonic treatment at a temperature of 50 - 60 °C for 1 - 2 h, and then centrifuge and dry.

[0006] Furthermore, for the above - mentioned antibacterial body wash containing modified zinc oxide, the wall material of the tea tree oil microcapsules is made by mixing β - cyclodextrin and gum arabic in a mass ratio of 1:2 - 3.

[0007] Furthermore, for the above - mentioned antibacterial body wash containing modified zinc oxide, the preparation method of the Lactobacillus fermentation filtrate includes: Inoculate Lactobacillus plantarum into an MRS medium containing 3 - 5% inulin, and perform anaerobic fermentation at 37 °C for 48 h, followed by ultrafiltration and sterilization.

[0008] Furthermore, for the above - mentioned antibacterial body wash containing modified zinc oxide, it also contains 0.1 - 0.3 parts by weight of resveratrol glucoside.

[0009] Furthermore, for the above - mentioned antibacterial body wash containing modified zinc oxide, the pH regulator is a citric acid - arginine buffer system, and the molar ratio of citric acid to arginine is 1:1.2 - 1.5.

[0010] Furthermore, for the above - mentioned antibacterial body wash containing modified zinc oxide, the 24 - hour antibacterial rate of the body wash against Escherichia coli ATCC25922 is ≥99.9%, and the skin irritation test score is below 0.3 points. The skin irritation test uses the patch test method.

[0011] The present invention also discloses a preparation method of the above - mentioned antibacterial body wash containing modified zinc oxide, which includes the following steps: 1) Premix modified zinc oxide with glycerol and ball mill for 2 h until D90 < 5 μm; 2) Dissolve cocamidopropyl betaine and sodium lauroyl sarcosinate in deionized water at 40 - 45 °C, and add the mixture from step 1); 3) Further add tea tree oil microcapsules, fermentation filtrate and the remaining components, and homogenize and emulsify (8000 rpm, 15 min); 4) Adjust the pH value to 5.5 - 6.5, age for 24 h and then fill.

[0012] Furthermore, in the above preparation method, nitrogen is introduced for protection during the homogenization process in step (3), and the oxygen content < 0.5 ppm.

[0013] The present invention also discloses the application of the above shower gel in the preparation of an external lotion for preventing Staphylococcus aureus infection.

[0014] The present invention also discloses the application of the above shower gel in the preparation of an anti-biofilm personal care product.

[0015] Compared with the prior art, the present invention has the following outstanding beneficial effects: The antibacterial shower gel of the present invention achieves significant breakthroughs in antibacterial efficiency, biofilm clearance, mildness and stability through the collaborative innovation of multiple components: 1. High-efficiency broad-spectrum antibacterial: After being double-modified by trisodium citrate and chitosan, the particle size of modified zinc oxide is controlled at D90 < 5 μm, the specific surface area increases, and the release rate of surface reactive oxygen species (ROS) decreases, reducing skin oxidative damage while ensuring the photocatalytic antibacterial efficiency (the antibacterial rate against Escherichia coli is 99.98%). Tea tree oil microcapsules slowly release terpene compounds (terpinene-4-ol, etc.) through the β-cyclodextrin / arabic gum wall material, disrupt the permeability of the bacterial cell membrane, and can form a dual bactericidal mechanism with the antibacterial peptide (Plantaricin) in the Lactobacillus fermentation filtrate, and the antibacterial rate against drug-resistant Staphylococcus aureus still reaches 99.95%.

[0016] 2. Deep anti-biofilm ability: The β-glucanase in the Lactobacillus fermentation filtrate can specifically degrade the extracellular polysaccharide (EPS) of the biofilm, enabling the effective penetration of tea tree oil to the bacterial cell layer. Experiments show that the clearance rate of mature biofilms is 89.6%, which is 68.4% higher than that of single components (comparative example 3). Because the photocatalytic effect of modified zinc oxide further decomposes eDNA and proteins in the biofilm, forming a "enzymatic hydrolysis - oxidation" synergistic clearance mode, breaking through the limitation of traditional surfactants that only remove planktonic bacteria.

[0017] 3. Mild and low irritation: The citric acid-arginine buffer system (pH 5.5-6.5) is adopted to match the natural acidic environment of the skin, reducing the damage of surfactants to the lipid barrier. Asiaticoside and resveratrol glucoside inhibit inflammatory factors and promote the proliferation of keratinocytes. The patch test shows that the irritation score is only 0.25 points, significantly lower than that of chemical bacteriostatic agents (the score of Comparative Example 4 is 1.2 points).

[0018] 4. Long-term stability: The nitrogen protection homogenization process (oxygen content < 0.5 ppm) inhibits the agglomeration of zinc oxide, and the bacteriostatic rate remains 99.6% after storage at 40°C for 90 days; the β-cyclodextrin / arabic gum wall material improves the thermal stability of tea tree oil (Tg = 78°C), and the release amount within 24 hours is < 15% in the accelerated test, avoiding the inactivation of active ingredients.

[0019] In summary, through component optimization and process innovation, the present invention solves the technical bottlenecks of traditional antibacterial body washes, such as high irritation, weak anti-biofilm ability, and poor stability, and is applicable to the care of sensitive skin and the prevention of drug-resistant bacterial infections, with significant market competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Comparison of the bacteriostatic rate (%) of Escherichia coli in body wash; Figure 2 Comparison of the bacteriostatic rate (%) of Staphylococcus aureus in body wash; Figure 3 Comparison of the test results of the biofilm clearance rate of body wash. DETAILED DESCRIPTION OF THE INVENTION

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] Table 1 Raw material table

[0023] Table 2 Equipment and instrument table

[0024] Example 1 Preparation of antibacterial body wash Components (by weight): Modified zinc oxide 8 parts Tea tree oil microcapsule 3 parts Lactobacillus fermentation filtrate 5 parts Asiaticoside 1.5 parts Resveratrol glucoside 0.3 part 25 parts of cocamidopropyl betaine 10 parts of sodium lauroyl sarcosinate 8 parts of glycerol 0.5 part of xanthan gum 0.1 part of disodium EDTA Citric acid - arginine buffer solution (citric acid:arginine = 1:1.5), adjusted to pH 6.5 Deionized water, made up to 100 parts Preparation method Step 1: Preparation of modified zinc oxide Disperse zinc oxide powder (particle size 100 nm) in 3% chitosan acetic acid solution (the solvent is 2% acetic acid aqueous solution), and the solid - liquid ratio is 1:10 (w / v).

[0025] Add trisodium citrate, and the molar ratio of zinc oxide to trisodium citrate is 1:1.2.

[0026] Ultrasonically treat in a 60 °C water bath for 2 hours (ultrasonic power 300 W, frequency 40 kHz).

[0027] Centrifuge (8000 rpm, 15 minutes) to collect the precipitate, wash it 3 times with deionized water, and vacuum - dry at 60 °C for 12 hours to obtain modified zinc oxide powder.

[0028] Step 2: Preparation of tea tree oil microcapsules I. Preparation of wall material solution 1. Preparation of β - cyclodextrin solution: Dissolve β - cyclodextrin in deionized water, and the concentration is fixed at 6% (w / v).

[0029] Heat to 55 °C and stir magnetically (500 rpm) until completely dissolved.

[0030] Add gum arabic powder and mix according to the mass ratio of β - cyclodextrin:gum arabic = 1:2.

[0031] Adjust the pH to 6.8 (using 0.1 M NaOH) and continuously stir for 30 minutes to form a homogeneous solution.

[0032] 2. Core material emulsification: Mix tea tree oil and Tween - 80 at a volume ratio of 1:0.2.

[0033] Homogenize at high speed (9000 rpm, 12 minutes) at 45 °C to form a stable oil - phase emulsion.

[0034] II. Microcapsule forming 1. Complex coacervation embedding: The emulsified tea tree oil was slowly added to the wall material solution at a core-wall ratio of 1:2 (mass ratio), with a stirring rate of 800 rpm.

[0035] The pH of the system was adjusted to 4.2 with 1 M citric acid and maintained for 30 minutes to promote the electrostatic crosslinking of β-cyclodextrin and gum arabic.

[0036] 2. Crosslinking and curing: Genipin was added (dosage: 0.2% of the total mass of the wall material), and curing was carried out at 38 °C for 1.5 hours.

[0037] The precipitate was separated by centrifugation (4000 rpm, 10 minutes) and washed 3 times with deionized water.

[0038] III. Drying and post-treatment 1. Spray drying: The solid content of the wet microcapsule suspension was adjusted to 4% (w / v).

[0039] Spray drying parameters: inlet air temperature 190 °C, outlet air temperature 85 °C, feed rate 5 mL / min.

[0040] Dry microcapsules were obtained, with D90 = 42 μm and encapsulation efficiency of 88.3%.

[0041] 2. Stability test: Under the accelerated test (40 °C / 75% humidity), the cumulative release amount was 13.5% in 24 hours and 21.7% in 48 hours.

[0042] Step 3: Preparation of Lactobacillus fermentation filtrate Lactobacillus plantarum was inoculated into MRS medium containing 4% inulin.

[0043] Anaerobic fermentation was carried out at 37 °C for 48 hours, and the cells were removed by centrifugation (10000 rpm, 10 minutes).

[0044] The filtrate was collected by ultrafiltration (molecular weight cut-off 10 kDa) and stored at 4 °C for later use.

[0045] Step 4: Preparation of body wash 1. Premixing of modified zinc oxide: Modified zinc oxide and glycerol were mixed in proportion and ball-milled for 2 hours (zirconia balls, ball-to-material ratio 5:1) to obtain a dispersion with D90 = 4.8 μm.

[0046] 2. Dissolution of surfactants: Cocamidopropyl betaine and sodium lauroyl sarcosinate were dissolved in deionized water at 45 °C and stirred until transparent.

[0047] 3. Homogenization and emulsification: Add the dispersion obtained in Step 1 to the surfactant solution.

[0048] Sequentially add tea tree oil microcapsules, Lactobacillus fermentation filtrate, asiaticoside, resveratrol glucoside, xanthan gum, and disodium EDTA.

[0049] Introduce nitrogen (oxygen content < 0.5 ppm) and perform homogenization emulsification (8000 rpm, 15 minutes).

[0050] 4. pH Adjustment and Aging: Adjust the pH to 6.5 with a citric acid - arginine buffer.

[0051] After aging for 24 hours, fill into containers.

[0052] Example 2 Adjust the component ratio: 5 parts of modified zinc oxide, 1 part of tea tree oil microcapsules, pH 6.0. The rest is the same as in Example 1.

[0053] Example 3 Omit resveratrol glucoside and reduce the Lactobacillus fermentation filtrate to 2 parts. The rest is the same as in Example 1.

[0054] Example 4 Adjust the wall material of the tea tree oil microcapsules to β - cyclodextrin: arabic gum = 1:3, and the pH regulator is citric acid - arginine (1:1.2), pH 5.5. The rest is the same as in Example 1.

[0055] Example 5 Adjust the proportion of trisodium citrate in the preparation of modified zinc oxide to 1:0.5 (molar ratio), and the ultrasonic time is 1 hour. The rest is the same as in Example 1.

[0056] Comparative Example 1 Omit modified zinc oxide and replace it with ordinary zinc oxide (unmodified). The rest is the same as in Example 1.

[0057] Comparative Example 2 Omit the Lactobacillus fermentation filtrate and replace it with an equal amount of deionized water. The rest is the same as in Example 1.

[0058] Comparative Example 3 The wall material of the tea tree oil microcapsules uses only β - cyclodextrin (without arabic gum). The rest is the same as in Example 1.

[0059] Comparative Example 4 Replace the pH regulator with sodium hydroxide and do not use a buffer system. The rest is the same as in Example 1.

[0060] Test Example 1 Determination of Bacteriostatic Rate Bacterial Strains and Culture Media: Test strains: Escherichia coli ATCC25922, Staphylococcus aureus ATCC6538 (purchased from ATCC, USA).

[0061] Media: Nutrient Broth (NB, Oxoid CM0001), Nutrient Agar (NA, Oxoid CM0003).

[0062] Preparation of bacterial suspension: Pick a single colony and inoculate it into 10 mL of NB, and culture it with shaking at 37 °C for 18 hours (180 rpm).

[0063] Centrifuge (3000 rpm, 10 minutes) to collect the bacterial cells, and wash them twice with sterile PBS (pH 7.2).

[0064] Adjust the concentration of the bacterial suspension to 1×10 6 CFU / mL (verified by the McFarland turbidity standard method, spectrophotometer OD600 = 0.08 - 0.1).

[0065] Sample treatment: Experimental group: Take 1 mL of the bacterial suspension and mix it with 19 mL of the body wash sample, and incubate at 37 °C for 24 hours.

[0066] Negative control: Bacterial suspension + 4 mL of sterile PBS (no antibacterial effect).

[0067] Positive control: Bacterial suspension + 4 mL of 75% ethanol (complete sterilization).

[0068] Viable count: Take 0.1 mL of the mixed solution and dilute it serially with PBS to 10⁻³.

[0069] Spread it on NA plates and culture at 37 °C for 24 hours, and count the number of colonies (CFU).

[0070] The formula for calculating the antibacterial rate is as follows:

[0071] Validity verification: The positive control group should show no bacterial growth, and the number of colonies in the negative control group should be ≥ 1×10 5 CFU / mL.

[0072] Repeatability: Each experiment is repeated 5 times, and the average value is taken.

[0073] The results are shown in Table 3 and Figure 1-2 .

[0074] Table 3 Results of antibacterial rate determination

[0075] From the above data, it can be seen that the antibacterial rates of Example 1 against Escherichia coli and Staphylococcus aureus both exceed 99.9%, which are significantly higher than those of Comparative Example 1 (ordinary zinc oxide) and Comparative Example 2 (filtrate without Lactobacillus). This result benefits from the multiple synergistic mechanisms of modified zinc oxide, tea tree oil microcapsules, and Lactobacillus fermentation filtrate: High-efficiency dispersibility of modified zinc oxide: Zinc oxide modified with trisodium citrate forms a uniform dispersion system (D90 < 5 μm) through ultrasonic treatment, with a specific surface area increased by 2.3 times and surface active sites fully exposed, thus enhancing the contact efficiency with the bacterial cell membrane.

[0076] Targeted anti-biofilm effect: Antibacterial peptides (such as Plantaricin) in the Lactobacillus fermentation filtrate can disrupt the integrity of the bacterial cell wall, while tea tree oil microcapsules penetrate the biofilm matrix by slowly releasing terpene compounds (such as terpinene-4-ol). The two work together to increase the degradation rate of key biofilm components (such as polysaccharides and eDNA) by 45%.

[0077] Analysis of the defects of the comparative examples: In Comparative Example 1, due to the agglomeration problem of ordinary zinc oxide (D90 > 20 μm), the release rate of the effective antibacterial component decreased by 60%; in Comparative Example 2, lacking the Lactobacillus fermentation filtrate and relying only on zinc oxide and tea tree oil, it was unable to break through the biofilm barrier, resulting in a 7.5% decrease in the antibacterial rate.

[0078] Test Example 2 Biofilm clearance rate Test method (modified crystal violet staining method): 1. Biofilm culture: Inoculate Staphylococcus aureus ATCC6538 into TSB medium containing 2% glucose and adjust the concentration to 1×10 6 CFU / mL.

[0079] Take 200 μL of the bacterial solution and add it to a 96-well plate, and incubate statically at 37°C for 48 hours (replace the fresh medium every 24 hours). [[ID=2B]]

[0080] 2. Sample treatment: Discard the medium and gently wash 3 times with PBS to remove planktonic bacteria.

[0081] Add 200 μL of the shower gel sample (diluted to 1% concentration to simulate the actual residual concentration) and treat it at 37°C for 6 hours.

[0082] 3. Staining and quantification: Fixation: Add 200 μL of methanol to fix for 15 minutes, discard the liquid and air dry.

[0083] Staining: Add 200 μL of 0.1% crystal violet solution and stain at room temperature for 20 minutes.

[0084] Decolorization: Wash 3 times with PBS, and add 200 μL of 95% ethanol to dissolve crystal violet.

[0085] Measurement: Transfer 100 μL of the solution to a new well plate, and measure the OD at 570 nm with an enzyme-linked immunosorbent assay (ELISA) reader.

[0086] 4. Calculation of clearance rate: Blank control: Wells without inoculated bacteria + same treatment.

[0087] Negative control: Wells of biofilms treated with PBS.

[0088] Clearance rate formula:

[0089] The test results are shown in Table 4 below and Figure 3 as follows.

[0090] Table 4 Test results of biofilm clearance rate

[0091] From the above data, it can be seen that the biofilm clearance rate of Example 1 (89.6%) is 68.4% higher than that of Comparative Example 3 (53.2%). The core reasons are as follows: Sustained-release advantage of the composite wall material: The β-cyclodextrin / arabic gum (1:2) wall material forms a dense cross-linked network in an acidic environment (pH 4.2), which can delay the release of tea tree oil and ensure the continuous action of active ingredients on the deep structure of the biofilm. When only β-cyclodextrin was used in Comparative Example 3, the release rate of tea tree oil was too fast, and the active ingredients were exhausted in a short time, unable to completely remove the biofilm.

[0092] EPS degradation synergism: The β-glucanase in the fermentation filtrate of Lactobacillus can specifically decompose the extracellular polysaccharide (EPS) of the biofilm, making it easier for tea tree oil to penetrate to the bacterial cell layer. In Comparative Example 4, no buffer system was used, and the alkaline environment (pH > 8) led to the loss of enzyme activity and a decrease in the clearance rate.

[0093] Test Example 3 Skin irritation test Test method (according to the "Cosmetics Safety and Technology Standards" 2015 edition): 1. Subject screening: 30 healthy volunteers (15 males and 15 females, aged 18 - 45 years), without a history of skin diseases, and signed an informed consent form.

[0094] Exclusion criteria: Pregnancy, allergic constitution, damage at the test site.

[0095] 2. Patch test: Sample preparation: undiluted shower gel stock solution, positive control (0.5% sodium dodecyl sulfate), negative control (physiological saline).

[0096] Patch application: Inject 0.02 mL of the sample into a Finn Chamber (8 mm in diameter), apply it to the back of the subject, and cover it with a breathable tape.

[0097] Time: Occlusive patch application for 48 hours, during which strenuous exercise should be avoided.

[0098] 3. Result determination: Observe the erythema / edema reaction 30 minutes and 24 hours after removing the patch, and score according to the following: Score 0: No reaction Score 1: Mild erythema (clear boundary) Score 2: Moderate erythema (accompanied by edema or papules) Score 3: Severe erythema (accompanied by blisters or erosions) 4. Irritation score: Calculate the average score of each subject, and the total score is the mean of the scores of all subjects.

[0099] Incidence of irritation (%) = (number of subjects with reactions / total number of subjects) × 100.

[0100] Test results: As shown in Table 5 below.

[0101] Table 5 Skin irritation test results

[0102] From the above data, it can be seen that the irritation score of Example 1 (0.25 points) is much lower than that of Comparative Example 4 (1.2 points). The key factors include: pH adaptation and barrier protection: The citric acid-arginine buffer system stabilizes the pH at 6.5, which highly matches the natural skin pH (5.5 - 6.5), avoiding the destruction of the lipid structure of the stratum corneum. In Comparative Example 4, NaOH was used to adjust the pH, resulting in local pH fluctuations (measured pH 7.8 - 8.2), which damaged the skin barrier function and caused an erythema reaction.

[0103] Synergistic effect of anti-inflammatory components: Resveratrol glucoside can theoretically reduce the release of inflammatory factors (IL-6, TNF-α) by inhibiting the NF-κB pathway. In addition, asiaticoside can also promote the proliferation of keratinocytes and accelerate skin repair.

[0104] Test Example 4 Centrifugal stability Sample treatment: Take 50 mL of the shower gel sample and dispense it into 10 centrifuge tubes (5 mL / tube).

[0105] Centrifugation conditions: 3000 rpm (relative centrifugal force 1000×g), 30 minutes, 25°C.

[0106] Result determination: Observe the phenomena of layering, precipitation or flocculation.

[0107] Calculation of the proportion of precipitates: Proportion of precipitates (%) = Volume of the precipitation layer / Total volume of the sample × 100% The results are shown in Table 6 below.

[0108] Table 6 Centrifugal stability test

[0109] From the data in Table 6, it can be seen that there is no layering phenomenon after centrifugation in Example 1, while 12.5% of zinc oxide precipitation occurs in Comparative Example 1. The reason is that: Surface modification and particle size control: After the modified zinc oxide is coated with chitosan, the electrostatic repulsion is enhanced, preventing particle aggregation. The ball milling process further controls the particle size within D90 < 5 μm (D90 of the unmodified zinc oxide in Comparative Example 1 > 50 μm), and the Stokes sedimentation rate is reduced by 90%.

[0110] System rheology optimization: Xanthan gum (0.5 parts) and cocamidopropyl betaine form a three-dimensional network structure, and the viscosity of the system reaches 3500 mPa·s (measured by Brookfield DV2T), significantly delaying sedimentation. In Comparative Example 1, due to the lack of stabilizer, the viscosity is only 800 mPa·s and cannot resist the centrifugal shear force.

[0111] Test Example 5 Storage stability Test method (according to the "Cosmetics Stability Test Guidelines"): Accelerated test: After the samples are sealed, they are placed in an incubator at 40°C (humidity 75%), and samples are taken for testing at 0, 30, 60, and 90 days respectively.

[0112] Test indicators: Bacteriostatic rate: The same method as in Test Example 1.

[0113] pH value: Measured with a pH meter (Mettler Toledo FE28), with temperature compensation at 25°C.

[0114] Appearance: Observe the changes in color, odor, and fluidity.

[0115] The results are shown in Table 7 below.

[0116] Table 7 Comparison of storage stability

[0117] As can be seen from the data in Table 7, the antibacterial rate of Example 1 only decreased by 0.36% after storage at 40°C for 90 days, while that of Comparative Example 2 decreased by 13.8%. The differences are as follows: Active ingredient protection mechanism: Nitrogen protection can inhibit the oxidative damage of the filtrate of Lactobacillus by the free radicals generated by the photocatalysis of zinc oxide.

[0118] Microcapsule thermal stability: The glass transition temperature (Tg) of the β-cyclodextrin / arabic gum wall material is about 78°C. At 40°C, there is no phase change in the wall material, and the retention rate of tea tree oil is high. In Comparative Example 2, the unencapsulated tea tree oil was directly exposed to the system and volatilized and lost at high temperature.

[0119] pH dynamic balance: The citric acid-arginine buffer system still maintains a pH of 6.4 - 6.5 at high temperature, preventing the precipitation of the anionic surfactant (sodium lauroyl sarcosinate) due to a decrease in pH (flocculation occurred in Comparative Example 2 when the pH dropped to 5.8).

[0120] Comprehensive analysis of the conclusions of the examples: The antibacterial body wash of the present invention has achieved triple breakthroughs in antibacterial rate, stability, and mildness through the optimization of modified zinc oxide dispersion, the anti-biofilm synergistic system, and the pH-skin barrier adaptation technology. The data of the comparative examples show that the absence or replacement of any core component (such as the filtrate of Lactobacillus, the buffer system, or the microcapsule wall material) will lead to a significant decrease in performance (the antibacterial rate decreases by ≥7.5%, and the irritation increases by ≥380%), fully verifying the necessity and synergy of the technical solution.

[0121] The above are only a limited number of preferred embodiments of the present invention, and the description is relatively specific and detailed. However, it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. An antibacterial body wash containing modified zinc oxide, characterized in that, Each 100 parts comprises the following components in parts by weight: Modified zinc oxide 3 - 8 parts Tea tree oil microcapsule 1 - 3 parts Lactobacillus fermentation filtrate 2 - 5 parts Asiaticoside 0.5 - 1.5 parts Cocamidopropyl betaine 15 - 25 parts Sodium lauroyl sarcosinate 5 - 10 parts Glycerol 3 - 8 parts Xanthan gum 0.1 - 0.5 parts Disodium EDTA 0.05 - 0.1 parts pH regulator appropriate amount to pH 5.5 - 6.5 Deionized water the balance; The preparation method of the modified zinc oxide is as follows: zinc oxide is dispersed in a 1 - 3% chitosan acetate solution, sodium citrate is added, and the molar ratio of zinc oxide to sodium citrate is 1:0.5 - 1.2, ultrasonic treatment is carried out at 50 - 60 °C for 1 - 2 h, and then centrifuged and dried.

2. The body wash according to claim 1, wherein The wall material of the tea tree oil microcapsule is made by mixing β - cyclodextrin and arabic gum according to a mass ratio of 1:2 - 3.

3. The body wash according to claim 1, wherein, The preparation method of the Lactobacillus fermentation filtrate includes: inoculating Lactobacillus plantarum into an MRS medium containing 3 - 5% inulin, anaerobically fermenting at 37 °C for 48 h, and then ultrafiltering to remove bacteria.

4. The body wash according to claim 1, wherein It also contains 0.1 - 0.3 parts by weight of resveratrol glucoside.

5. The body wash according to claim 1, characterized in that, The pH regulator is a citric acid - arginine buffer system, and the molar ratio of citric acid to arginine is 1:1.2 - 1.

5.

6. The body wash according to claim 1, wherein The 24 - hour antibacterial rate of the shower gel against Escherichia coli ATCC25922 is ≥99.9%, and the skin irritation test score is below 0.3 points. The skin irritation test uses the patch test method.

7. The preparation method of the shower gel according to any one of claims 1-6, characterized in that, Including the following steps: 1) Premix the modified zinc oxide and glycerol, ball - mill for 2 h until D90 < 5 μm; 2) Dissolve cocamidopropyl betaine and sodium lauroyl sarcosinate in deionized water at 40 - 45 °C, and add the mixture in step 1); 3) Further add the tea tree oil microcapsule, fermentation filtrate and other components, and homogenize and emulsify (8000 rpm, 15 min); 4) Adjust the pH value to 5.5 - 6.5, age for 24 h and then fill.

8. The method according to claim 7, characterized in that During the homogenization process in step 3), nitrogen is introduced for protection, and the oxygen content < 0.5 ppm.

9. Use of the shower gel according to any one of claims 1 - 6 in the preparation of an external lotion for preventing Staphylococcus aureus infection.

10. Use of the shower gel according to any one of claims 1 - 6 in the preparation of an anti - biofilm personal care product.

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