Antibacterial skin care emulsion containing silver oxide and method for its production

Abstract

The application discloses an antibacterial skin care emulsion containing silver oxide and a preparation method thereof, and belongs to the skin care field.The antibacterial skin care emulsion containing silver oxide comprises the following components in percentage by weight: 0.01-3% of silver oxide; 5-30% of a plant oil phase; 2-12% of an emulsifying system; 3-20% of a polyhydric alcohol moisturizing system; 0.05-5% of an interfacial stabilizing system; 0.05-6% of a gradient coating system; 0.2-5% of a network locking system; 0.02-2% of an ion adjusting system; and the balance of a water phase.The preparation method comprises the following steps: S1, adding the gradient coating system into the water phase; S2, adding the silver oxide to form a gradient coating layer; S3, mixing the plant oil phase and the emulsifying system to form an oil phase; S4, adding the oil phase into the silver oxide dispersion system to form an initial emulsion; S5, adding the network locking system and the ion adjusting system; S6, performing dynamic interfacial ripening treatment; and S7, cooling.The application has the beneficial effects that the dispersion stability, controllable release and long-term antibacterial performance of the silver oxide in the skin care emulsion are improved.

Description

Technical Field

[0001] This invention relates to the field of skincare, and more specifically, to an antibacterial skincare lotion containing silver oxide and its preparation method. Background Technology

[0002] With the development of skincare product technology, antibacterial skincare lotions have gradually evolved from simple moisturizing care to encompass skin protection, microecological regulation, and functional care. Early antibacterial skincare lotions primarily used organic antibacterial agents as active ingredients. With the development of nanomaterials technology, silver oxide, due to its good antibacterial properties and chemical stability, has been increasingly applied to skincare lotion systems. Current technology improves the stability of silver oxide in skincare products by incorporating silver oxide particles into the lotion formula, combined with emulsifiers, thickeners, and moisturizing components, thus promoting the development of antibacterial skincare lotions towards higher stability and multifunctionality.

[0003] However, existing silver oxide-containing antibacterial skincare emulsions still have certain shortcomings: silver oxide usually exists in a freely dispersed form in the emulsion system, which easily leads to particle aggregation, sedimentation, and uneven local concentration during long-term storage; at the same time, the lack of a stable interfacial structure between silver oxide and the internal components of the emulsion makes it difficult to control the release process of silver oxide, affecting the sustainability of antibacterial performance; in addition, traditional emulsion preparation processes mainly rely on simple emulsification and cooling molding, making it difficult to accurately control the spatial distribution of silver oxide, which easily leads to a decrease in the structural stability of the emulsion. Therefore, it is necessary to construct a novel silver oxide antibacterial skincare emulsion system with interfacial confinement fixation, gradient coating, and structural locking functions to improve the long-term stability and performance of the product. Summary of the Invention

[0004] This invention proposes an antibacterial skin care emulsion containing silver oxide and its preparation method to solve the aforementioned problems: silver oxide usually exists in emulsion systems in a free-dispersed form, and is prone to particle aggregation, sedimentation, and uneven local concentration during long-term storage; at the same time, the lack of a stable interface structure between silver oxide and the internal components of the emulsion makes it difficult to control the release process of silver oxide, affecting the sustainability of antibacterial performance; in addition, traditional emulsion preparation processes mainly rely on simple emulsification and cooling molding, which makes it difficult to accurately control the spatial distribution of silver oxide, easily leading to a decrease in the structural stability of the emulsion.

[0005] Technical Solution: An antibacterial skin care lotion containing silver oxide, comprising the following components by weight percentage: silver oxide 0.01%–3%; plant oil phase 5%–30%; emulsification system 2%–12%; polyol moisturizing system 3%–20%; interface stabilizing system 0.05%–5%; gradient encapsulation system 0.05%–6%; network locking system 0.2%–5%; ion regulation system 0.02%–2%; and the remainder being an aqueous phase. The gradient coating system coats the surface of the silver oxide to form an inner coating layer and an outer coating layer; the interface stabilization system drives the silver oxide to migrate to the oil-water interface formed by the plant oil phase and the aqueous phase; the network locking system forms a continuous three-dimensional network and fixes the dispersed oil droplets formed by the plant oil phase; the silver oxide forms an interface confinement and fixation structure through the gradient coating system and the network locking system.

[0006] Preferably, the gradient coating system includes a first coating layer and a second coating layer. The first coating layer is directly adsorbed onto the surface of the silver oxide, and the second coating layer coats the outside of the first coating layer. The bonding strength of the first coating layer is greater than that of the second coating layer, so that the silver oxide forms a gradient bonding structure.

[0007] Preferably, the interface stabilization system enables the silver oxide to continuously migrate to the oil-water interface during emulsion formation and forms a continuous interface distribution structure along the oil-water interface, the continuous interface distribution structure covering at least 60% of the outer surface of the dispersed oil droplets.

[0008] Preferably, the network locking system forms a continuous three-dimensional cross-linked network, which forms a spatial connection structure with the gradient coating system and the vegetable oil phase, thereby restricting the migration distance of the silver oxide.

[0009] Preferably, the method for preparing the silver oxide-containing antibacterial skin care lotion includes the following steps: S1. The gradient coating system is added to the aqueous phase to form the first dispersion system; S2. Add silver oxide to the first dispersion system to form a gradient coating layer on the surface of the silver oxide; S3. Mix the vegetable oil phase with the emulsion system to form an oil phase; S4. The oil phase is added to the gradient-coated silver oxide dispersion system to form an initial emulsion; S5. Add a network locking system and an ion regulation system to the initial emulsion to allow the silver oxide to migrate to the oil-water interface and form an interface confined and fixed structure; S6. Perform dynamic interface maturation treatment on the initial emulsion to rearrange the gradient coating layers and complete interface stabilization; S7. Cooling yields an antibacterial skin lotion containing silver oxide.

[0010] Preferably, the S6 dynamic interface ripening process includes an alternating heating stage and a cooling stage, wherein the alternating heating stage and the cooling stage are cycled at least twice to cause the gradient coating layer to undergo interface rearrangement.

[0011] Preferably, during the S6 dynamic interface maturation process, the emulsion is kept in a low-shear state, causing the silver oxide to redistribute along the oil-water interface and form a continuous interface coating layer.

[0012] Preferably, the S5 ion regulation system is added before the network locking system forms a continuous three-dimensional network, so as to stabilize the interface potential of the silver oxide surface and inhibit irreversible aggregation between the silver oxide particles.

[0013] Preferably, after the S6 dynamic interface ripening process is completed, the interface is left to ripen statically, so that the gradient overlay layer and the network locking system form a stable connection structure, and the interface confinement and fixing structure remains stable.

[0014] Preferably, during the S6 dynamic interface ripening process, by adjusting the rearrangement degree of the gradient coating layer, the crosslinking degree of the network locking system, and the stability of the ion regulation system, the spatial distribution of silver oxide at the oil-water interface is kept stable, and the interface migration and crystal ripening degree of silver oxide during long-term storage are reduced.

[0015] Compared with the prior art, the advantages of the present invention are as follows: (1) By constructing the gradient coating system, an inner coating layer and an outer coating layer are formed on the surface of silver oxide, which replaces the method of directly dispersing silver oxide in the emulsion system in the prior art, reduces the risk of silver oxide particle aggregation and deactivation, and improves the long-term stability of silver oxide in the emulsion.

[0016] (2) By controlling the migration of silver oxide to the oil-water interface formed by the vegetable oil phase and the water phase, the silver oxide forms an interface-confined fixed structure, which changes the state of the antibacterial components being randomly distributed in the continuous phase in the prior art and improves the spatial distribution uniformity of silver oxide.

[0017] (3) By setting up a network locking system, a continuous three-dimensional network structure is formed inside the emulsion, which spatially constrains the dispersed oil droplets and the interface confinement and fixation structure, thereby reducing the problems of emulsion phase separation and silver oxide migration during long-term storage.

[0018] (4) By introducing a dynamic interface maturation process, the gradient coating layer undergoes further interface rearrangement after the emulsion is formed, which improves the stability of the silver oxide coating structure, unlike the existing process of directly cooling and shaping after the emulsion is prepared.

[0019] (5) By leveraging the synergistic effect of the gradient coating system, the interface stabilization system, and the network locking system, the release state of silver oxide can be regulated, thus avoiding the problem of rapid release of silver oxide leading to a shortened effective action time in the prior art.

[0020] (6) By regulating the dispersion environment of silver oxide through the ion regulation system, the irreversible aggregation between silver oxide particles is reduced, thereby improving the structural stability of silver oxide emulsions during long-term storage.

[0021] (7) By using the oil-water interface directional assembly method, silver oxide is transformed from the traditional bulk dispersion mode to the interface distribution mode, which improves the utilization efficiency of silver oxide and reduces the problem of increasing the amount of silver oxide added in order to achieve antibacterial effect.

[0022] (8) Through the coordinated control of composition structure design and preparation process, the silver oxide stabilization process is transformed from a single physical dispersion to a multi-stage regulation process of coating, positioning and locking, forming a new stable system that is different from traditional silver oxide antibacterial skin care lotion. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall process for preparing an antibacterial skin care lotion containing silver oxide according to the present invention. Detailed Implementation Example

[0025] Examples 1-5 Example 1. An antibacterial skin care emulsion containing silver oxide, comprising the following weight percentages: silver oxide 0.01%–3%; plant oil phase 5%–30%; emulsification system 2%–12%; polyol moisturizing system 3%–20%; interface stabilizing system 0.05%–5%; gradient encapsulation system 0.05%–6%; network locking system 0.2%–5%; ion regulation system 0.02%–2%; and the balance being an aqueous phase. The gradient coating system coats the surface of silver oxide to form an inner coating layer and an outer coating layer; the interface stabilization system drives the silver oxide to migrate to the oil-water interface formed by the vegetable oil phase and the water phase; the network locking system forms a continuous three-dimensional network and fixes the dispersed oil droplets formed by the vegetable oil phase; the silver oxide forms an interface confinement and fixation structure through the gradient coating system and the network locking system.

[0026] The gradient coating system includes a first coating layer and a second coating layer. The first coating layer is directly adsorbed onto the surface of silver oxide, and the second coating layer coats the outside of the first coating layer. The bonding strength of the first coating layer is greater than that of the second coating layer, so that the silver oxide forms a gradient bonding structure.

[0027] The interface stabilization system enables silver oxide to continuously migrate to the oil-water interface during emulsion formation and forms a continuous interface distribution structure along the oil-water interface, which covers at least 60% of the outer surface of the dispersed oil droplets.

[0028] The network locking system forms a continuous three-dimensional cross-linked network, which forms a spatial connection structure with the gradient coating system and the vegetable oil phase, respectively, thus restricting the migration distance of silver oxide.

[0029] A method for preparing an antibacterial skin care lotion containing silver oxide includes the following steps: S1. The gradient coating system is added to the aqueous phase to form the first dispersion system; S2. Add silver oxide to the first dispersion system to form a gradient coating layer on the surface of silver oxide; S3. Mix the vegetable oil phase with the emulsion system to form an oil phase; S4. Add the oil phase to the gradient-coated silver oxide dispersion system to form an initial emulsion; S5. Add a network locking system and an ion regulation system to the initial emulsion to allow silver oxide to migrate to the oil-water interface and form an interfacial confined and fixed structure; S6. Perform dynamic interface maturation treatment on the initial emulsion to rearrange the gradient coating layers and complete interface stabilization. S7. Cooling yields an antibacterial skin lotion containing silver oxide.

[0030] The S6 dynamic interface ripening process includes alternating heating and cooling stages, which are repeated at least twice to cause interface rearrangement of the gradient coating layer.

[0031] During the S6 dynamic interface maturation process, the emulsion is kept in a low-shear state, causing silver oxide to redistribute along the oil-water interface and form a continuous interface coating layer.

[0032] The S5 ion regulation system is added before the network locking system forms a continuous three-dimensional network, which stabilizes the interfacial potential of the silver oxide surface and inhibits irreversible aggregation between silver oxide particles.

[0033] After the S6 dynamic interface ripening process is completed, it is kept statically ripening so that the gradient coating layer and the network locking system form a stable connection structure, and the interface confinement fixed structure remains stable.

[0034] During the S6 dynamic interface ripening process, by adjusting the rearrangement degree of the gradient coating layer, the crosslinking degree of the network locking system, and the stability of the ion regulation system, the spatial distribution of silver oxide at the oil-water interface is kept stable, and the interfacial migration and crystal ripening degree of silver oxide during long-term storage are reduced.

[0035] Example 2. This example provides an antibacterial skin care lotion containing silver oxide.

[0036] By weight percentage, it includes: 0.05% silver oxide; 15% vegetable oil phase; and 6% emulsion system. Polyol moisturizing system 10%; interface stabilizing system 1%; gradient coating system 2%; network locking system 2%; ion regulation system 0.5%; aqueous phase balance.

[0037] The preparation process involves the following components: squalane as the plant oil phase; glyceryl stearate as the emulsification system; glycerol as the polyol moisturizing system; polyglycerol fatty acid ester as the interface stabilization system; a gradient coating system comprising a polydopamine first coating layer and a carboxymethyl chitosan second coating layer; sodium hyaluronate as the network locking system; and zinc gluconate as the ion regulation system. In the preparation process, carboxymethyl chitosan is dispersed in the aqueous phase to form a first dispersion system. After adding silver oxide, a first and second coating layer are formed on the surface of the silver oxide. Squalane and glyceryl stearate are then mixed to form an oil phase, which is then added to the silver oxide dispersion system for emulsification. After emulsification, sodium hyaluronate and zinc gluconate are added to allow the silver oxide to gradually migrate to the oil-water interface. A dynamic interface maturation treatment is then performed, consisting of a 30-minute heating at 40°C and a 30-minute cooling at 25°C, repeated three times. Finally, the mixture is allowed to stand for 120 minutes and then cooled to obtain an antibacterial skincare emulsion containing silver oxide.

[0038] Example 3. This example provides an antibacterial skin care lotion containing silver oxide.

[0039] By weight percentage, it includes: 0.5% silver oxide; 20% vegetable oil phase; 8% emulsification system; 12% polyol moisturizing system; 2% interface stabilization system; 3% gradient coating system; 3% network locking system; 1% ion regulation system; and the balance being aqueous phase.

[0040] The preparation process involves the following components: the plant oil phase is caprylic / capric triglyceride; the emulsification system is lecithin; the polyol moisturizing system is propylene glycol; the interface stabilization system is polyglutamic acid; the gradient coating system includes a polydopamine first coating layer and a sodium hyaluronate second coating layer; the network locking system is microcrystalline cellulose; and the ion regulation system is magnesium gluconate. In the preparation process, sodium hyaluronate is added to the aqueous phase to form a first dispersion system. Silver oxide particles with a particle size of 150 nm are then added, allowing sodium hyaluronate and polydopamine to be sequentially adsorbed onto the silver oxide surface to form a gradient coating layer. Subsequently, caprylic / capric triglyceride and lecithin are mixed to form an oil phase, which is then added to the silver oxide dispersion system to form an initial emulsion. Microcrystalline cellulose and magnesium gluconate are added to the initial emulsion to redistribute the silver oxide along the oil-water interface and form an interface-confined and fixed structure. During the dynamic interface curing process, the temperature was raised to 45℃ for 20 minutes and lowered to 20℃ for 40 minutes, alternating cycles were repeated 4 times. After curing, the mixture was left to stand for 180 minutes to obtain an antibacterial skin care lotion containing silver oxide.

[0041] Example 4. This example provides an antibacterial skin care lotion containing silver oxide.

[0042] By weight percentage, it includes: 1% silver oxide; 25% vegetable oil phase; 10% emulsification system; 15% polyol moisturizing system; 3% interface stabilization system; 4% gradient coating system; 4% network locking system; 1.5% ion regulation system; and the balance being aqueous phase.

[0043] The plant oil phase used is jojoba oil; the emulsification system uses polyglycerol fatty acid esters; the polyol moisturizing system uses butylene glycol; the interface stabilization system uses carboxymethyl chitosan; the gradient coating system uses a double-layer coating structure composed of polydopamine and sodium hyaluronate; the network locking system uses xanthan gum; and the ion regulation system uses calcium gluconate. The dynamic interface ripening treatment involves alternating cycles of a 50°C heating stage and a 30°C cooling stage five times, with each heating stage held for 20 minutes and each cooling stage held for 40 minutes. Through this preparation method, silver oxide forms a continuous interface covering structure and restricts the migration of silver oxide particles in the emulsion.

[0044] Example 5. This example provides an antibacterial skin care lotion containing silver oxide.

[0045] By weight percentage, it includes: 2% silver oxide; 30% vegetable oil phase; 12% emulsification system; 18% polyol moisturizing system; 5% interface stabilization system; 6% gradient coating system; 5% network locking system; 2% ion regulation system; and the balance being aqueous phase.

[0046] The plant oil phase used is sunflower seed oil; the emulsification system uses glyceryl stearate and lecithin; the polyol moisturizing system uses glycerol and propylene glycol; the interface stabilization system uses polyglutamic acid; the gradient coating system uses a polydopamine first coating layer and a carboxymethyl chitosan second coating layer; the network locking system uses carbomer; and the ion regulation system uses zinc gluconate. During the preparation process, a low-shear dynamic interface ripening treatment is used to reduce the mechanical disturbance to the silver oxide particles and maintain a stable interface distribution of silver oxide.

[0047] Comparative Example Comparative Examples 1-5 Comparative Example 1. This comparative example provides an antibacterial skin care emulsion containing silver oxide. Compared with Example 3, the gradient coating system is not used. In the preparation process, silver oxide is directly added to the aqueous phase for dispersion, and then mixed and emulsified with the oil phase. The remaining components and preparation conditions are the same as in Example 3. Because the silver oxide does not form a first coating layer and a second coating layer, the silver oxide particles are prone to agglomeration during storage, resulting in particle aggregation inside the emulsion.

[0048] Comparative Example 2. This comparative example provides an antibacterial skin care lotion containing silver oxide. Compared with Example 3, the interface stabilization system is not provided. In the preparation process, the silver oxide is directly added to the oil-water mixture after coating, and the remaining steps are the same. Due to the lack of an interface stabilization system, the silver oxide cannot continuously migrate to the oil-water interface, resulting in the silver oxide being mainly distributed in the continuous aqueous phase, and the interface coverage is reduced.

[0049] Comparative Example 3. This comparative example provides an antibacterial skin care emulsion containing silver oxide. Compared with Example 4, the network locking system is not added. During the preparation process, the emulsification is directly followed by a aging process. Due to the lack of a continuous three-dimensional network structure, the stability of the oil droplet structure inside the emulsion decreases, the migration distance of silver oxide increases, and uneven distribution is easily generated during long-term storage.

[0050] Comparative Example 4. This comparative example provides an antibacterial skin care lotion containing silver oxide. Compared with Example 4, the dynamic interface ripening treatment was omitted. After preparation, it was directly cooled to room temperature. The results show that, due to the lack of alternating heating and cooling stages, the gradient coating layer could not fully undergo interface rearrangement, and the degree of formation of the silver oxide interface fixed structure was reduced.

[0051] Comparative Example 5. This comparative example provides an antibacterial skin care emulsion containing silver oxide. Compared with Example 5, the gradient coating system was replaced with a common water-soluble thickener. During the preparation process, silver oxide was fixed to the emulsion system only through physical thickening. Due to the lack of synergistic effect between the gradient coating structure and the network locking structure, silver oxide is prone to local aggregation, resulting in reduced long-term stability of the emulsion.

[0052] To determine the interfacial immobilization stability and long-term storage stability of silver oxide in the examples and comparative examples, the following comparative experiment was designed, and the experimental steps are as follows: Experimental Objective: This experiment was conducted to test the silver oxide distribution stability of antibacterial skin care emulsions containing silver oxide prepared in different embodiments and comparative examples during long-term storage. By detecting the silver oxide sedimentation rate, particle size change rate, interface coverage, and antibacterial performance retention rate after emulsion storage, the experiment verified the effect of the interface confinement and fixation structure formed by the gradient coating system, interface stabilization system, network locking system, and dynamic interface ripening treatment of this invention on improving emulsion stability.

[0053] Preparation of experimental materials: The experimental samples included antibacterial skin care lotions containing silver oxide prepared in Examples 2, 3, 4 and 5, as well as silver oxide lotions prepared in Comparative Examples 1, 2, 3, 4 and 5.

[0054] The experimental testing instruments included a high-speed centrifuge to detect phase separation after centrifugation of the emulsion; a laser particle size analyzer to detect changes in the particle size of silver oxide particles before and after storage; a scanning electron microscope to observe the distribution of silver oxide particles in the emulsion; an optical microscope to observe the oil-water interface structure inside the emulsion; a UV-Vis spectrophotometer to detect the release stability of silver oxide; and a constant temperature storage chamber to simulate a long-term storage environment.

[0055] The experimental reagents included Escherichia coli culture; Staphylococcus aureus culture; sterile culture medium; sterile water; and standard buffer solutions.

[0056] The specific experimental steps are as follows: Sample pretreatment: 50g of silver oxide emulsions prepared in Examples 2, 3, 4, and 5, and Comparative Examples 1, 2, 3, 4, and 5 were taken from each group and placed in sealed transparent sample bottles. All samples were placed in a constant temperature storage environment of 25°C, while an accelerated storage environment of 40°C was set to simulate the changes in emulsion structure during long-term storage.

[0057] Storage stability test: Samples were taken and tested on days 0, 30, 60, and 90 of storage. Each emulsion sample was added to a centrifuge tube and centrifuged at 3000 rpm for 30 minutes. The presence of obvious oil-water separation was observed, and the emulsion separation height was recorded. The sedimentation rate was calculated based on the total sample height and the separation layer height.

[0058] Silver oxide particle size change detection: Emulsion samples were taken before and after storage, and the average particle size of silver oxide particles was measured using a laser particle size analyzer. During the test, the emulsion was diluted to the same concentration, and the same detection parameters were used for measurement. The change in silver oxide particle size before and after storage was recorded. The lower the particle size change rate, the lower the degree of silver oxide particle aggregation and the higher the emulsion stability.

[0059] Silver oxide interface distribution detection: The internal structure of each emulsion group was observed using scanning electron microscopy and optical microscopy. The concentration of silver oxide particles in the oil-water interface region was observed, and the proportion of oil droplets covered by silver oxide was calculated. One hundred oil droplets from the emulsion were randomly selected as statistical subjects, and the proportion of oil droplets with continuous silver oxide interface coverage was calculated out of the total number of detected oil droplets.

[0060] Silver oxide release stability test: Each group of stored emulsion samples was added to a buffer solution, and silver oxide release experiments were conducted under the same temperature and time conditions. The concentration of silver in the released solution was measured using a UV-Vis spectrophotometer. The stability of the silver oxide release process was evaluated by the change in release concentration after different storage times.

[0061] Antimicrobial performance retention rate test: Emulsion samples were collected from each group after 0 days and 90 days of storage. Equal masses of emulsion samples were added to a culture system containing *Escherichia coli* and *Staphylococcus aureus*. After 24 hours of incubation, changes in colony counts were measured. The antimicrobial performance retention rate was calculated based on the changes in inhibition rate before and after storage.

[0062] The specific experimental data are shown in Table 1: Table 1

[0063] Experimental Conclusions and Analysis: The experimental results show that the silver oxide-containing antibacterial skin care emulsions prepared in Examples 2 to 5 all exhibited low sedimentation rates and small silver oxide particle size change rates during 90 days of storage. Example 5 showed a sedimentation rate of only 0.7% and a silver oxide particle size change rate of 3.5%, significantly better than the comparative examples. Comparative Example 1 did not use a gradient coating system, and the silver oxide was directly dispersed in the emulsion system, leading to easy aggregation of silver oxide particles, resulting in a higher particle size change rate and lower interface coverage. This indicates that the gradient coating system can effectively improve the stability of silver oxide particles. Comparative Example 2 did not include an interface stabilization system, and the silver oxide could not effectively migrate to the oil-water interface to form a continuous distribution structure, thus significantly reducing the interface coverage. This indicates that the interface stabilization system can promote the formation of an interface-confined and fixed structure of silver oxide. Comparative Example 3 did not include a network locking system, and the lack of a continuous three-dimensional network structure inside the emulsion led to an increased migration distance of silver oxide and a decrease in storage stability. This indicates that the network locking system can enhance the spatial fixation effect of silver oxide. In Comparative Example 4, the performance of all components decreased after the dynamic interface ripening treatment was removed, indicating that the dynamic interface ripening treatment can promote the rearrangement of the gradient coating layers and improve the stability of the interface structure. In Comparative Example 5, a common thickening method was used to replace the gradient coating system and the network locking system, which failed to form a stable interface confinement and fixation structure, resulting in a significant reduction in the stability of silver oxide release and the retention rate of antibacterial properties.

[0064] In summary, this invention utilizes the synergistic effect of a gradient coating system, an interface stabilization system, a network locking system, and a dynamic interface ripening treatment to enable silver oxide to form a stable interface-confined and fixed structure in the emulsion system. This effectively reduces silver oxide aggregation, migration, and performance degradation during storage, thereby improving the long-term stability of silver oxide-containing antibacterial skin care emulsions.

[0065] To determine the silver oxide release regulation performance and antibacterial persistence performance in the examples and comparative examples, the following comparative experiment was designed, and the experimental steps are as follows: Experimental Objective: This experiment aims to evaluate the release behavior and sustained antibacterial activity of silver oxide in different samples, focusing on verifying the effect of the present invention's gradient coating system, interface confinement and fixation structure, and dynamic interface ripening treatment on regulating the silver oxide release rate. Existing silver oxide emulsions often suffer from the problem of direct exposure of silver oxide to the emulsion environment, leading to an excessively rapid initial release rate and a shortened effective action period. This experiment simulates a skin environment and detects changes in silver oxide release concentration and sustained antibacterial effect after different storage times to verify the regulatory effect of the present invention on the silver oxide release process.

[0066] Preparation of experimental materials: Experimental samples included antibacterial skin care lotions containing silver oxide prepared in Examples 2, 3, 4, and 5; and silver oxide emulsions prepared in Comparative Examples 1, 2, 3, 4, and 5. Experimental instruments included a constant temperature water bath to simulate skin temperature; a UV-Vis spectrophotometer to detect the concentration of silver in the release solution; an inductively coupled plasma mass spectrometer to detect trace amounts of silver; a constant temperature incubator for antibacterial experiments; an electronic balance for sample weighing; and a centrifuge for sample pretreatment. Experimental materials included phosphate buffer; *Escherichia coli* culture; *Staphylococcus aureus* culture; sterile petri dishes; and sterile filter membranes.

[0067] The specific experimental steps are as follows: Silver oxide release simulation experiment: 5g samples of the emulsions prepared in Examples 2-5 and Comparative Examples 1-5 were weighed from each group. Each emulsion group was placed in a dialysis apparatus, and 50mL of phosphate buffer was added as the external release medium. All samples were placed in a constant temperature environment of 32℃ to simulate the temperature conditions of human skin surface. Release media were collected at 2h, 6h, 12h, 24h, 48h, and 72h after the start of the release experiment. An equal volume of fresh phosphate buffer was added after each sampling to maintain a consistent total volume of the release system. The concentration of silver in the release medium was detected using inductively coupled plasma mass spectrometry to obtain the amount of silver oxide released at different time stages.

[0068] Initial release rate test of silver oxide: The initial release rate of silver oxide was calculated based on the silver elemental concentrations detected at 2h and 6h. By comparing the early release rates of different samples, the limiting effect of the gradient coating system on the rapid release of silver oxide was evaluated.

[0069] Continuous release stability test: Based on the release data at 24h, 48h, and 72h, the change in silver release per unit time for each group of samples was calculated. If the change in the release curve is small, it indicates that the silver oxide release process is more stable.

[0070] Sustained antibacterial performance test: Emulsion release solutions were collected at 2h, 24h, 48h, and 72h after the release experiment. The release solutions were added to culture systems containing *Escherichia coli* and *Staphylococcus aureus*, respectively. After 24h of incubation, the antibacterial effect at different time points was detected by colony counting. The inhibition rate was calculated based on the colony count.

[0071] Antibacterial performance retention rate calculation: The antibacterial rate 2 hours after release was taken as the initial antibacterial performance, and the antibacterial rate 72 hours later was compared with the initial antibacterial performance.

[0072] The formula for calculating the antibacterial performance retention rate is as follows: Antibacterial performance retention rate = 72h inhibition rate ÷ 2h inhibition rate × 100%.

[0073] The higher the retention rate of antibacterial properties, the more stable the silver oxide release process and the stronger its sustained effect.

[0074] The specific experimental data are shown in Table 2: Table 2

[0075] Experimental Conclusions and Analysis: The experimental results show that the silver oxide-containing antibacterial skin care emulsions prepared in Examples 2 to 5 all exhibited low initial release rates and high sustained release stability. Among them, Example 5 showed the most stable silver release process within 72 hours, with a release stability coefficient of 98.0% and an antibacterial performance retention rate of 97.4%. In Comparative Example 1, due to the lack of a gradient coating system, the silver oxide particles directly contacted the release medium, leading to rapid silver release in the early stages, with a release amount reaching 35.8% after 2 hours, significantly higher than the Example group. This indicates that the gradient coating system can reduce the initial release rate of silver oxide. In Comparative Example 2, without an interface stabilization system, the silver oxide could not fully form a confined and fixed structure at the oil-water interface, resulting in an unstable silver oxide release process. This indicates that the interface stabilization system can regulate the spatial distribution of silver oxide and control its release behavior. In Comparative Example 3, without a network locking system, the internal structural constraint of the emulsion was reduced, making silver oxide more prone to migration, thus significantly increasing the release rate. This indicates that the continuous three-dimensional network structure can enhance the fixation effect of silver oxide. Comparative Example 4, which did not undergo dynamic interface ripening treatment, did not fully complete the interface rearrangement in the gradient coating layer, resulting in decreased silver oxide release stability. This indicates that dynamic interface ripening treatment can further optimize the interface structure. Comparative Example 5, which used a conventional thickening method to replace the gradient coating system and network locking system in this invention, could not form a stable silver oxide interface confinement structure, thus exhibiting a faster release rate and a lower antibacterial retention rate.

[0076] In summary, this experiment demonstrates that the present invention, through the synergistic effect of a gradient coating system, an interface stabilization system, a network locking system, and a dynamic interface ripening treatment, transforms silver oxide from a traditional rapid release mode to a stable and controllable release mode, thereby improving the duration of effective action of silver oxide while ensuring antibacterial efficacy.

Claims

1. An antibacterial skin care lotion containing silver oxide, characterized in that, It comprises the following components by weight percentage: silver oxide 0.01%–3%; vegetable oil phase 5%–30%; emulsification system 2%–12%; polyol moisturizing system 3%–20%; interface stabilizing system 0.05%–5%; gradient coating system 0.05%–6%; network locking system 0.2%–5%; ion regulation system 0.02%–2%; and the balance being aqueous phase. The gradient coating system coats the surface of the silver oxide to form an inner coating layer and an outer coating layer; the interface stabilization system drives the silver oxide to migrate to the oil-water interface formed by the plant oil phase and the aqueous phase; the network locking system forms a continuous three-dimensional network and fixes the dispersed oil droplets formed by the plant oil phase; the silver oxide forms an interface confinement and fixation structure through the gradient coating system and the network locking system.

2. The antibacterial skin care lotion containing silver oxide according to claim 1, characterized in that, The gradient coating system includes a first coating layer and a second coating layer. The first coating layer is directly adsorbed onto the surface of the silver oxide, and the second coating layer coats the outside of the first coating layer. The bonding strength of the first coating layer is greater than that of the second coating layer, so that the silver oxide forms a gradient bonding structure.

3. The antibacterial skin care lotion containing silver oxide according to claim 1, characterized in that, The interface stabilization system enables the silver oxide to continuously migrate to the oil-water interface during emulsion formation and forms a continuous interface distribution structure along the oil-water interface, which covers at least 60% of the outer surface of the dispersed oil droplets.

4. The antibacterial skin care lotion containing silver oxide according to claim 1, characterized in that, The network locking system forms a continuous three-dimensional cross-linked network, which forms a spatial connection structure with the gradient coating system and the vegetable oil phase, thereby restricting the migration distance of the silver oxide.

5. According to any one of claims 1 to 4, a method for preparing a silver oxide-containing antibacterial skin care lotion is designed, characterized in that... The method for preparing the silver oxide-containing antibacterial skin care lotion includes the following steps: S1. The gradient coating system is added to the aqueous phase to form the first dispersion system; S2. Add silver oxide to the first dispersion system to form a gradient coating layer on the surface of the silver oxide; S3. Mix the vegetable oil phase with the emulsion system to form an oil phase; S4. The oil phase is added to the gradient-coated silver oxide dispersion system to form an initial emulsion; S5. Add a network locking system and an ion regulation system to the initial emulsion to allow the silver oxide to migrate to the oil-water interface and form an interface confined and fixed structure; S6. Perform dynamic interface maturation treatment on the initial emulsion to rearrange the gradient coating layers and complete interface stabilization; S7. Cooling yields an antibacterial skin lotion containing silver oxide.

6. The method for preparing an antibacterial skin care lotion containing silver oxide according to claim 5, characterized in that, The S6 dynamic interface ripening process includes an alternating heating stage and a cooling stage, which are repeated at least twice to cause the gradient coating layer to undergo interface rearrangement.

7. The method for preparing an antibacterial skin care lotion containing silver oxide according to claim 5, characterized in that, During the S6 dynamic interface maturation process, the emulsion is kept in a low-shear state, causing the silver oxide to redistribute along the oil-water interface and form a continuous interface coating layer.

8. The method for preparing an antibacterial skin care lotion containing silver oxide according to claim 5, characterized in that, The S5 ion regulation system is added before the network locking system forms a continuous three-dimensional network, so that the interface potential of the silver oxide surface tends to be stable and the irreversible aggregation between the silver oxide particles is inhibited.

9. The method for preparing an antibacterial skin care lotion containing silver oxide according to claim 5, characterized in that, After the S6 dynamic interface ripening process is completed, it is kept in a static ripening state so that the gradient overlay layer and the network locking system form a stable connection structure, and the interface confinement and fixing structure remains stable.

10. The method for preparing an antibacterial skin care lotion containing silver oxide according to claim 5, characterized in that, During the S6 dynamic interface ripening process, by adjusting the rearrangement degree of the gradient coating layer, the crosslinking degree of the network locking system, and the stability of the ion regulation system, the spatial distribution of silver oxide at the oil-water interface is kept stable, and the interface migration and crystal ripening degree of silver oxide during long-term storage are reduced.

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