Eye protection composition based on natural extracts and preparation process thereof

Abstract

The present invention relates to the technical field of natural eye protection preparations, disclosing an eye protection composition based on natural extracts and its preparation process. The preparation process comprises the steps of preparing microcapsules with inner wall materials, adding an enzymatic directional cross-linking system, constructing outer wall materials, forming an antioxidant synergistic circulation structure, performing layer-by-layer osmotic diffusion treatment, and drying the microcapsules. By combining a double-wall microencapsulation structure with a dynamic cross-linking network, the present invention significantly improves the stability and bioavailability of natural eye protection active ingredients, extending the product's shelf life, while simultaneously achieving the mutual regeneration of antioxidants and the structural repair function of the microcapsules.

Description

Technical Field

[0001] The present invention relates to the technical field of natural eye protection preparations, and more particularly to an eye protection composition based on natural extracts and a preparation process thereof. Background Art

[0002] With the widespread use of electronic products, eye fatigue and vision problems caused by blue light radiation are becoming increasingly prominent. Natural plant extracts such as caper fruit extract, lutein, wild chrysanthemum extract, and cassia seed extract are widely used in eye care products due to their significant eye-protecting benefits. However, these natural active ingredients generally suffer from issues such as susceptibility to oxidation, photosensitivity, and poor stability. They are easily degraded during preparation, storage, and use, severely limiting their practical application.

[0003] The existing preparation process of eye protection compositions mainly has the following technical problems: the protective structure formed by traditional microencapsulation technology has poor stability and is easily destroyed by external factors such as moisture, skin secretions and mechanical friction, resulting in rapid release and degradation of active ingredients; conventional antioxidant protection systems will gradually be exhausted during use, and the protective effect will significantly weaken over time; eye protection active ingredients of different polarities are difficult to coexist stably in the same carrier system, which limits the development of comprehensive eye protection formulas; traditional spray drying or freeze drying processes often lead to significant degradation of heat-sensitive eye protection ingredients during the microcapsule preparation process.

[0004] Therefore, there is an urgent need to develop a new eye protection composition and its preparation process that can effectively protect natural eye protection active ingredients and improve their stability and bioavailability. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides an eye protection composition based on natural extracts and a preparation process thereof.

[0006] A preparation process of an eye protection composition based on natural extracts comprises the following steps:

[0007] Step 1: Mix the natural eye protection active ingredients with carrier oil to form an oil phase mixture;

[0008] Step 2: Dispersing the oil phase mixture into the inner wall material aqueous solution containing gelatin, gum arabic and sodium alginate to form a water-in-oil emulsion;

[0009] Step 3: adding at least three natural antioxidants with different modes of action to the emulsion to form an antioxidant synergistic circulation structure;

[0010] Step 4: adding an enzyme system and a natural cross-linking agent precursor to cause an enzymatic directional cross-linking reaction in the inner wall material;

[0011] Step 5: constructing an outer wall material composed of polysaccharides to form a double-layer microcapsule structure;

[0012] Step 6: Perform layer-by-layer infiltration and diffusion treatment to form a gradient distribution of the antioxidant in the microcapsule wall material;

[0013] Step 7: Mix the treated double-layer microcapsules with a polyvinyl alcohol aqueous solution and perform electrospinning in a low-temperature, oxygen-free environment to obtain a nanoscale fibrous microcapsule network product.

[0014] Preferably, the natural eye-protecting active ingredients include capparis spinosa fruit extract, lutein, wild chrysanthemum flower extract and cassia seed extract, which are mixed in a weight ratio of 3:2:2:1.

[0015] Preferably, the carrier oil is a mixture of olive oil, evening primrose oil and linseed oil in a weight ratio of 2:1:1.

[0016] Preferably, three natural antioxidants with different modes of action include: the first type of antioxidant is rosemary extract, added in an amount of 0.5-1.0% by weight of the total oil phase; the second type of antioxidant is green tea extract, added in an amount of 0.8-1.2% by weight of the total aqueous phase; the third type of antioxidant is vitamin E, added in an amount of 0.3-0.6% by weight of the total oil phase.

[0017] Preferably, the enzyme system includes horseradish peroxidase and laccase, and the natural cross-linking agent precursor includes tea polyphenols and chitosan oligosaccharides.

[0018] Preferably, the enzymatic directional cross-linking reaction is carried out at pH 6.0-6.5 and temperature 25-30° C. for 2-4 hours.

[0019] Preferably, the outer wall material is composed of sodium alginate and low-methoxy pectin, and is formed by ionic cross-linking induced by calcium chloride solution.

[0020] Preferably, the layer-by-layer osmotic diffusion treatment is carried out in an ethanol aqueous solution containing 0.3% rosmarinic acid, 0.5% tea polyphenols and 0.2% tocopherol, with an ethanol content of 30%, a temperature of 25° C., and a treatment time of 4-6 hours.

[0021] Preferably, electrospinning is carried out under the conditions of a high voltage electric field of 15-18 kV, a spinning distance of 15-20 cm and a feed rate of 0.5-1.0 mL / h, with the temperature controlled at 20±2° C. and the relative humidity controlled at 40±5%.

[0022] An eye protection composition based on natural extracts is prepared by the above-mentioned preparation process, comprising a double-layer wall material microcapsule structure and an antioxidant synergistic circulation structure, wherein the inner wall material of the microcapsule contains multiple natural antioxidants, and the outer wall material of the microcapsule is composed of polysaccharides.

[0023] The beneficial effects of the present invention are:

[0024] The stability of natural eye protection active ingredients is improved. Accelerated stability tests (40°C, 75% relative humidity, 3 months) show that the residual rate of active ingredients in the eye protection composition prepared by the present invention reaches more than 85%, which is more than 70% higher than that of traditional microencapsulation technology.

[0025] The double-walled microcapsule structure has high mechanical strength and environmental adaptability. Under conditions such as simulated skin secretions (mixed salt solution with a pH of 5.5) and mechanical friction (100 reciprocating frictions under a pressure of 250g), the microcapsule structural integrity retention rate is as high as 80%, which is 40% higher than that of traditional microcapsules.

[0026] The antioxidant synergistic cycle structure achieves mutual regeneration of antioxidants, extending the duration of the protective effect by 3-5 times, avoiding the cost increase and side effects caused by the excessive addition of antioxidants in traditional methods;

[0027] The dynamic cross-linking network gives the microcapsules the ability to repair their structure. When the microcapsule structure is slightly damaged, the remaining active enzymes continue to catalyze the cross-linking reaction to repair the structural defects, thereby improving the stability and durability of the product under various application conditions.

[0028] The nanoscale fibrous microcapsule network formed by electrospinning technology has a large specific surface area and good biocompatibility, allowing the active ingredients to more effectively contact the ocular tissue during use, thereby improving bioavailability;

[0029] The entire process uses natural raw materials and preparation processes, without synthetic cross-linking agents, avoiding potential toxicity issues and improving product safety;

[0030] This technology can be widely used in various eye patches, eye creams, eye essences and other products, and has good industrialization prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a curve showing the change of the residual rate of the active ingredient of the present invention over time;

[0032] Figure 2 is a hydrolysis stability test curve of the present invention;

[0033] Figure 3 is the skin secretion stability test curve of the present invention;

[0034] Figure 4 It is the mechanical friction stability test curve of the present invention. DETAILED DESCRIPTION

[0035] The subject matter described herein will now be discussed with reference to example embodiments. It should be understood that these embodiments are discussed solely to enable those skilled in the art to better understand and implement the subject matter described herein, and that the functions and arrangements of the elements discussed may be varied without departing from the scope of this specification. Various examples may omit, substitute, or add various processes or components as needed. Furthermore, features described in some examples may be combined in other examples.

[0036] At least one embodiment of the present invention discloses a process for preparing an eye protection composition based on natural extracts, comprising the following steps:

[0037] Step 1: Mix the natural eye protection active ingredients with carrier oil to form an oil phase mixture;

[0038] Step 2: Dispersing the oil phase mixture into the inner wall material aqueous solution containing gelatin, gum arabic and sodium alginate to form a water-in-oil emulsion;

[0039] Step 3: adding at least three natural antioxidants with different modes of action to the emulsion to form an antioxidant synergistic circulation structure;

[0040] Step 4: adding an enzyme system and a natural cross-linking agent precursor to cause an enzymatic directional cross-linking reaction in the inner wall material;

[0041] Step 5: constructing an outer wall material composed of polysaccharides to form a double-layer microcapsule structure;

[0042] Step 6: Perform layer-by-layer infiltration and diffusion treatment to form a gradient distribution of the antioxidant in the microcapsule wall material;

[0043] Step 7: Mix the treated double-layer microcapsules with a polyvinyl alcohol aqueous solution and perform electrospinning in a low-temperature, oxygen-free environment to obtain a nanoscale fibrous microcapsule network product.

[0044] At least one embodiment of the present invention discloses that the natural eye protection active ingredient includes capparis spinosa fruit extract, lutein, wild chrysanthemum flower extract and cassia seed extract, which are mixed in a weight ratio of 3:2:2:1.

[0045] At least one embodiment of the present invention discloses that the carrier oil is a mixture of olive oil, evening primrose oil and linseed oil in a weight ratio of 2:1:1.

[0046] At least one embodiment of the present invention discloses three natural antioxidants with different modes of action: the first type of antioxidant is rosemary extract, added in an amount of 0.5% of the total weight of the oil phase; the second type of antioxidant is green tea extract, added in an amount of 0.8% of the total weight of the aqueous phase; the third type of antioxidant is vitamin E, added in an amount of 0.3% of the total weight of the oil phase.

[0047] At least one embodiment of the present invention discloses three natural antioxidants with different modes of action, including: a first type of antioxidant is rosemary extract, added in an amount of 1.0% of the total weight of the oil phase; a second type of antioxidant is green tea extract, added in an amount of 1.2% of the total weight of the aqueous phase; and a third type of antioxidant is vitamin E, added in an amount of 0.6% of the total weight of the oil phase.

[0048] At least one embodiment of the present invention discloses three natural antioxidants with different modes of action, including: a first type of antioxidant is rosemary extract, added in an amount of 0.8% of the total weight of the oil phase; a second type of antioxidant is green tea extract, added in an amount of 1.0% of the total weight of the aqueous phase; and a third type of antioxidant is vitamin E, added in an amount of 0.4% of the total weight of the oil phase.

[0049] At least one embodiment of the present invention discloses that the enzyme system includes horseradish peroxidase and laccase, and the natural cross-linking agent precursor includes tea polyphenols and chitosan oligosaccharides.

[0050] At least one embodiment of the present invention discloses that the enzymatic directional cross-linking reaction is carried out at pH 6.0 and 25° C. for 2 hours.

[0051] At least one embodiment of the present invention discloses that the enzymatic directional cross-linking reaction is carried out at pH 6.5 and temperature 30° C. for 4 hours.

[0052] At least one embodiment of the present invention discloses that the enzymatic directional cross-linking reaction is carried out at pH 6.3 and 28° C. for 3 hours.

[0053] Preferably, the outer wall material is composed of sodium alginate and low-methoxy pectin, and is formed by ionic cross-linking induced by calcium chloride solution.

[0054] At least one embodiment of the present invention discloses that the layer-by-layer osmotic diffusion treatment is carried out in an ethanol aqueous solution containing 0.3% rosmarinic acid, 0.5% tea polyphenols and 0.2% tocopherol, with an ethanol content of 30%, a temperature of 25° C., and a treatment time of 4 hours.

[0055] At least one embodiment of the present invention discloses that the layer-by-layer osmotic diffusion treatment is carried out in an ethanol aqueous solution containing 0.3% rosmarinic acid, 0.5% tea polyphenols and 0.2% tocopherol, with an ethanol content of 30%, a temperature of 25° C., and a treatment time of 6 hours.

[0056] At least one embodiment of the present invention discloses that the layer-by-layer osmotic diffusion treatment is carried out in an ethanol aqueous solution containing 0.3% rosmarinic acid, 0.5% tea polyphenols and 0.2% tocopherol, with an ethanol content of 30%, a temperature of 25° C., and a treatment time of 5 hours.

[0057] At least one embodiment of the present invention discloses that electrospinning is carried out under the conditions of a high voltage electric field of 15 kV, a spinning distance of 15 cm and a feed rate of 0.5 mL / h, the temperature is controlled at 20+2°C, and the relative humidity is controlled at 40+5%.

[0058] At least one embodiment of the present invention discloses that electrospinning is carried out under the conditions of a high voltage electric field of 18 kV, a spinning distance of 20 cm and a feed rate of 1.0 mL / h, with the temperature controlled at 20-2° C. and the relative humidity controlled at 40-5%.

[0059] At least one embodiment of the present invention discloses that electrospinning is carried out under the conditions of a high voltage electric field of 17 kV, a spinning distance of 18 cm and a feed rate of 0.8 mL / h, with the temperature controlled at 20° C. and the relative humidity controlled at 40%.

[0060] At least one embodiment of the present invention discloses an eye protection composition based on natural extracts, which is prepared by the above-mentioned preparation process and includes a double-layer wall material microcapsule structure and an antioxidant synergistic circulation structure, wherein the inner wall material of the microcapsule contains a variety of natural antioxidants, and the outer wall material of the microcapsule is composed of polysaccharides.

[0061] Specific implementation examples

[0062] A preparation process of an eye protection composition based on natural extracts, comprising the following specific steps:

[0063] 1. Active ingredient pretreatment

[0064] Natural eye-protecting active ingredients (Capparis spinosa fruit extract, lutein, wild chrysanthemum flower extract, and Cassia tora seed extract) were mixed in a weight ratio of 3:2:2:1 and then blended with a carrier oil (a mixture of olive oil, evening primrose oil, and linseed oil in a weight ratio of 2:1:1) in the dark to produce an oil phase mixture. Nitrogen was introduced during the mixing process to remove oxygen from the system and reduce oxidation of the active ingredients.

[0065] During the pretreatment of the active ingredients, low temperature (no higher than 30°C), light protection, and inert gas protection are employed to maintain the original activity of each active ingredient. This step, by selecting an appropriate combination of carrier oils, allows the stable coexistence of eye-protecting active ingredients with significantly different polarities, laying the foundation for subsequent microencapsulation.

[0066] 2 Preparation of inner wall material and initial microcapsule formation

[0067] Gelatin (molecular weight approximately 100,000 Daltons, isoelectric point 4.8-5.2) was selected as the primary inner wall material and dissolved in 40°C deionized water to create a 5% aqueous solution. To this solution, 0.5% gum arabic and 0.3% sodium alginate were added as auxiliary wall materials to form a composite inner wall material aqueous solution.

[0068] The oil phase mixture prepared in step 1 is dispersed into the inner wall material aqueous solution under high-speed shear conditions of 4000-6000 rpm to obtain a preliminary water-in-oil emulsion. The emulsification process is carried out at a low temperature (20-25°C) under an inert gas atmosphere to minimize oxidation of the active ingredients.

[0069] 3 Construction of inner antioxidant synergistic circulation structure

[0070] This step achieves long-term protection of active ingredients by constructing an antioxidant synergistic circulation structure in the inner wall material.

[0071] Three natural antioxidants with different modes of action are added to the emulsion obtained in step 2 in sequence: 1) a first type of antioxidant: rosemary extract (containing rosmarinic acid and rosmarinic phenol, which are fat-soluble free radical scavengers), added in an amount of 0.5-1.0% by weight of the total oil phase; 2) a second type of antioxidant: green tea extract (containing catechin compounds, which are water-soluble free radical scavengers), added in an amount of 0.8-1.2% by weight of the total aqueous phase; 3) a third type of antioxidant: vitamin E (α-tocopherol, which is a chain-breaking antioxidant), added in an amount of 0.3-0.6% by weight of the total oil phase.

[0072] By controlling the order and ratio of these three antioxidants, they form a synergistic, cyclical antioxidant structure: when the first antioxidant is oxidized, it is reduced by the second; when the second antioxidant is oxidized, it is reduced by the third antioxidant; and the third antioxidant can be regenerated under certain conditions. This synergistic antioxidant cycle prolongs the duration of the antioxidant protection effect, providing long-term protection for the active ingredients.

[0073] 4 Enzymatic directional cross-linking treatment

[0074] This step combines the natural enzymatic directional cross-linking method with the microcapsule preparation process to achieve controllable cross-linking and reinforcement of the microcapsule structure.

[0075] The specific operation is as follows: 0.01-0.05% horseradish peroxidase (HRP, activity not less than 250 U / mg) and 0.005-0.02% laccase (activity not less than 10 U / mg) are added to the system obtained in step 3 as a cross-linking catalytic enzyme system. At the same time, 0.3-0.5% tea polyphenols (content ≥95%) and 0.2-0.4% chitosan oligosaccharide (deacetylation degree ≥90%, molecular weight 5000-8000 Da) are added as natural cross-linking agent precursors.

[0076] The enzymatic crosslinking reaction is carried out within the inner wall material at a pH of 6.0-6.5 and a temperature of 25-30°C for 2-4 hours. During this process, the enzyme system catalyzes the formation of covalent crosslinks between tea polyphenols and chitosan oligosaccharides, enhancing the mechanical strength and stability of the inner wall material. Compared to chemical crosslinking methods, the enzymatic directional crosslinking method employed in this step offers high selectivity and mild reaction conditions, minimizing the loss of active ingredients while also imparting a degree of structural repair capabilities to the inner wall material.

[0077] 5. Outer wall material construction and double-layer microcapsule formation

[0078] This step forms a complete double-layer microcapsule structure by constructing the outer wall material, further enhancing the protection effect of the active ingredients.

[0079] The microcapsules obtained in step 4 were collected by centrifugation (3000 rpm for 5 minutes), gently washed once, and then dispersed in an aqueous solution containing 2% sodium alginate and 1% low-methoxyl pectin. The mixture was stirred gently (200-300 rpm) for 1 hour to allow the polysaccharides to adsorb onto the microcapsule surface, forming a preliminary outer layer.

[0080] Subsequently, a 0.5% calcium chloride solution is added dropwise (at a controlled rate of 2-3 mL / min) to ionically crosslink the outer polysaccharide layer, forming a stable outer wall. This ionic crosslinking process occurs at room temperature, preventing thermal damage to the active ingredients. The outer wall provides an additional physical barrier to the inner microcapsules, preventing the intrusion of external factors such as oxygen, light, and moisture.

[0081] In this step, polysaccharides are used to construct the outer wall material, which enhances the physical stability of the microcapsule and forms a density gradient structure through ionic cross-linking, giving the microcapsule environmental adaptability and controlled release properties.

[0082] 6-layer infiltration and diffusion treatment

[0083] In this step, the antioxidant forms a gradient distribution in the microcapsule wall material through a layer-by-layer infiltration and diffusion process, thereby constructing a dynamic cross-linking network.

[0084] The specific procedure is to disperse the bilayer microcapsules obtained in step 5 in an ethanol-water solution (30% ethanol content) containing 0.3% rosmarinic acid, 0.5% tea polyphenols, and 0.2% tocopherol, and gently stir at 25°C for 4-6 hours. During this process, the different antioxidants form a gradient distribution within the microcapsule wall due to their respective diffusion rates: rosmarinic acid is primarily distributed in the outer wall, tea polyphenols form an enrichment zone at the junction of the inner and outer wall materials, and tocopherol is mainly concentrated in the inner wall material.

[0085] This gradient distribution allows the various antioxidants to interact and form redox pairs. When one antioxidant is oxidized, it is reduced by the adjacent antioxidant, establishing a complete antioxidant synergistic cycle. Simultaneously, the enzyme system (HRP and laccase) continues to catalyze the cross-linking reaction, forming a dynamic cross-linked network in the microcapsule wall material, which possesses structural repair capabilities.

[0086] 7 Electrospinning and final product formation

[0087] This step uses electrospinning technology to replace traditional spray drying or freeze drying processes to prepare nanoscale fibrous microcapsule networks in a low-temperature, oxygen-free environment.

[0088] The specific operation is to mix the bilayer microcapsule suspension obtained in step 6 with an aqueous solution of polyvinyl alcohol (PVA, degree of hydrolysis ≥99%, molecular weight 70,000-90,000) in a volume ratio of 1:2 to produce a spinning solution. This solution is then loaded into a syringe and electrospun using a high-voltage electric field of 15-18 kV, a spinning distance of 15-20 cm, and a feed rate of 0.5-1.0 mL / h. The spinning process is carried out in a nitrogen-filled environment, with a temperature of 20±2°C and a relative humidity of 40±5%.

[0089] Through electrospinning, the microcapsules are encapsulated within nanoscale PVA fibers, forming a fibrous network structure with high porosity and a large surface area. This structure enhances the mechanical strength and stability of the microcapsules while maintaining excellent breathability and sustained-release properties. Compared to traditional drying methods, electrospinning is performed at low temperatures and in the absence of oxygen, minimizing degradation of heat-sensitive eye protection ingredients during the preparation process and preserving the original activity of the active ingredients.

[0090] The final product is a white or light yellow soft fibrous material, which can be processed into patches, tablets or powder products as needed and used to prepare various eye protection preparations.

[0091] Experimental Example

[0092] To validate the technical effects of the present invention, the following experimental tests were conducted. These experiments were designed to demonstrate the advantages of the eye protection composition of the present invention in terms of active ingredient stability, microcapsule structural strength, long-lasting antioxidant effect, structural repair ability, and biocompatibility. The experimental results are presented in tabular and graphical form and compared with a control group.

[0093] Experiment 1: Active ingredient stability test

[0094] Purpose of the experiment

[0095] The stability of the natural active ingredients in the eye protection composition prepared by the present invention was verified and compared with the product prepared by traditional microencapsulation technology.

[0096] Experimental Materials

[0097] The eye protection composition prepared by the present invention (experimental group);

[0098] Eye protection composition prepared by traditional single-layer microencapsulation technology (control group 1);

[0099] a mixture of non-microencapsulated eye protection active ingredients (control group 2);

[0100] High performance liquid chromatography (HPLC);

[0101] Constant temperature and humidity chamber.

[0102] Experimental methods

[0103] The samples of the experimental group, control group 1 and control group 2 were placed in a constant temperature and humidity chamber at 40°C and 75% relative humidity for accelerated stability testing;

[0104] Samples were collected at 0, 15, 30, 60, and 90 days, and the contents of the main active ingredients (lutein, zeaxanthin from Capparis spinosa fruit extract, chlorogenic acid from Chrysanthemum indicum extract, and quercetin from Cassia seed extract) in each sample were determined by HPLC.

[0105] Calculate the residual rate of active ingredients at each time point (i.e., the percentage of current content to initial content);

[0106] Each test was repeated 3 times and the average value was taken.

[0107] Experimental results

[0108] Table 1. Residual rate of active ingredients in each group of samples in the accelerated stability test (%)

[0109]

[0110] Figure 1 : Curve of active ingredient residual rate changing with time.

[0111] Result Analysis

[0112] From Table 1 and Figure 1 As can be seen, after 90 days of accelerated stability testing, the eye protection composition prepared by the present invention (experimental group) had an active ingredient residual rate of 85.7%, while the product prepared by traditional microencapsulation technology (control group 1) and the non-microencapsulated active ingredient mixture (control group 2) had residual rates of only 50.2% and 14.3%, respectively. This demonstrates that the present invention significantly improves the stability of natural eye protection active ingredients through the combination of a double-wall microencapsulation structure and an antioxidant synergistic circulation structure.

[0113] Experiment 2: Microcapsule structural strength and environmental adaptability test

[0114] Purpose of the experiment

[0115] The structural integrity and stability of the microcapsule structure prepared by the present invention under different environmental conditions were evaluated to verify its mechanical strength and environmental adaptability.

[0116] Experimental Materials

[0117] The eye protection composition prepared by the present invention (experimental group);

[0118] an eye protection composition prepared using conventional single-layer microencapsulation technology (control group);

[0119] Simulated skin secretions (mixed salt solution with a pH of 5.5, containing 0.9% NaCl, 0.1% lactic acid, and 0.1% urea);

[0120] Mechanical friction testing device (capable of applying 250g pressure and performing reciprocating friction);

[0121] Laser confocal microscopy;

[0122] Scanning electron microscopy (SEM).

[0123] Experimental methods

[0124] Hydrolytic stability test:

[0125] The samples of the experimental group and the control group were immersed in pure water and cultured at 37°C;

[0126] Samples were taken at 0 h, 6 h, 12 h, 24 h, and 48 h, and the structural integrity of the microcapsules was observed using a laser confocal microscope;

[0127] Calculate the percentage of intact microcapsules to the total number of microcapsules;

[0128] Skin secretion stability test:

[0129] The samples of the experimental group and the control group were immersed in simulated skin secretions and cultured at 37°C;

[0130] Samples were taken at 0 h, 6 h, 12 h, 24 h, and 48 h, and the structural integrity of the microcapsules was observed using a laser confocal microscope;

[0131] The percentage of intact microcapsules to the total number of microcapsules was calculated.

[0132] Mechanical friction stability test:

[0133] The experimental group and control group samples were placed on the mechanical friction test device respectively;

[0134] The friction was repeated 10 times, 50 times, 100 times, 150 times and 200 times under a pressure of 250g.

[0135] The microcapsule morphology was observed using SEM and the structural integrity was calculated;

[0136] Each test was repeated 3 times and the average value was taken.

[0137] Experimental results

[0138] Table 2-1. Microcapsule integrity rate (%) in hydrolysis stability test

[0139]

[0140] Table 2-2. Microcapsule integrity rate (%) in skin secretion stability test

[0141]

[0142] Table 2-3. Microcapsule integrity rate (%) in mechanical friction stability test

[0143]

[0144] Figure 2 : Hydrolysis stability test curve.

[0145] Figure 3 : Skin secretion stability test curve.

[0146] Figure 4 : Mechanical friction stability test curve.

[0147] Result Analysis

[0148] From Table 2-1, Table 2-2, Table 2-3 and Figure 2 、 3 , 4 can be seen:

[0149] Hydrolytic stability: After being immersed in water for 48 hours, the structural integrity of the microcapsules prepared by the present invention is still maintained at 87.1%, while that of traditional microcapsules is only 51.2%, an increase of 70.1%.

[0150] Skin secretion stability: After being immersed in simulated skin secretions for 48 hours, the microcapsules prepared by the present invention have a structural integrity rate of 82.5%, while that of traditional microcapsules is only 46.3%, an increase of 78.2%.

[0151] Mechanical friction stability: After 100 reciprocating frictions, the structural integrity of the microcapsules prepared by the present invention was 87.6%, while that of the traditional microcapsules was only 58.3%, an increase of 50.3%; even after 200 reciprocating frictions, the integrity of the microcapsules of the present invention was still maintained at 77.8%, while that of the traditional microcapsules dropped to 40.2%.

[0152] The above results prove that the present invention significantly improves the mechanical strength and environmental adaptability of the microcapsules through the double-layer wall material structure and enzymatic directional cross-linking technology, so that the microcapsules have excellent stability under conditions such as hydrolysis, skin secretions and mechanical friction, which is of great significance for the practical application of eye protection products.

[0153] Experiment 3: Antioxidant synergistic circulation effect test

[0154] Purpose of the experiment

[0155] The durability and effectiveness of the antioxidant synergistic circulation structure of the present invention were verified, and the differences between it and conventional antioxidant protection systems were compared.

[0156] Experimental Materials

[0157] The eye protection composition containing an antioxidant synergistic circulation structure prepared by the present invention (experimental group A);

[0158] an antioxidant composition containing the same amount but without a synergistic cyclic structure (control group B);

[0159] a composition containing a single antioxidant (vitamin E) (Control C);

[0160] oxygen free radical generator (AAPH, 2,2'-azobis(2-methylpropionamide) dihydrochloride);

[0161] fluorescent probe (DCFH-DA, 2′,7′-dichlorofluorescein diacetate);

[0162] UV-visible spectrophotometer;

[0163] Fluorescence spectrophotometer;

[0164] High performance liquid chromatography (HPLC).

[0165] Experimental methods

[0166] Test of antioxidant capacity over time:

[0167] The samples of experimental group A, control group B and control group C were placed under the conditions of 37°C and 75% relative humidity;

[0168] Samples were collected on days 0, 7, 14, 21, and 28;

[0169] The ORAC method (oxygen radical absorbance capacity) was used to determine the antioxidant capacity of each sample;

[0170] The antioxidant capacity was expressed as Trolox equivalent (μmol TE / g).

[0171] Determination of antioxidant content:

[0172] The changes in the contents of three antioxidants (rosmarinic acid in rosemary extract, epigallocatechin gallate (EGCG) in green tea extract, and vitamin E) in each group of samples were determined using HPLC.

[0173] Calculate the residual rate of antioxidants at each time point;

[0174] Free radical scavenging ability test:

[0175] Each group of samples was mixed with AAPH and the DCFH-DA fluorescent probe was added;

[0176] The cells were incubated at 37°C, and the fluorescence intensity changes were measured every 1 hour (excitation wavelength 485 nm, emission wavelength 525 nm);

[0177] Draw a curve of fluorescence intensity changes over time within 24 hours to reflect the persistence of the sample's ability to scavenge free radicals;

[0178] Each test was repeated 3 times and the average value was taken;

[0179] Experimental results

[0180] Table 3-1. Changes in antioxidant capacity over time (μmol TE / g)

[0181]

[0182] Table 3-2. Changes in antioxidant residual rate over time (%)

[0183]

[0184] Result Analysis

[0185] From Table 3-1 and Table 3-2, we can see that:

[0186] Long-lasting antioxidant capacity: After 28 days, the eye protection composition of the present invention (experimental group A) still maintained 83.3% of its initial antioxidant capacity (204.7 / 245.6 x 100%), while the composition containing the same amount of antioxidants but without a synergistic cyclic structure (control group B) only maintained 38.1% (92.6 / 243.2 x 100%). The composition containing a single antioxidant (control group C) dropped to 21.9% (31.2 / 142.5 x 100%). This indicates that the antioxidant synergistic cyclic structure of the present invention prolongs the antioxidant protection effect by approximately 3-4 times.

[0187] Antioxidant Stability: In the eye protection composition of the present invention, the residual rates of the three antioxidants (rosmarinic acid, EGCG, and vitamin E) after 28 days were 82.5%, 84.7%, and 77.2%, respectively, compared to only 41.8%, 36.5%, and 38.9% in control group B. This demonstrates that the antioxidant synergistic cycle structure significantly enhances the stability of the antioxidants themselves, enabling them to protect and regenerate each other.

[0188] Long-lasting free radical scavenging ability: After 24 hours of continuous exposure to a free radical generator, the eye protection composition of the present invention maintained approximately 56.8% of its free radical scavenging ability, while control group B and control group C saw their free radical scavenging ability drop to 16% and 0%, respectively. This further demonstrates that the antioxidant synergistic cycle structure can maintain long-lasting antioxidant protection.

[0189] The above results show that the present invention realizes the mutual regeneration of antioxidants by constructing an antioxidant synergistic circulation structure, significantly prolongs the duration of the antioxidant protection effect, avoids the problem of rapid exhaustion of the antioxidant system in traditional methods, and provides more lasting and effective protection for natural eye protection active ingredients.

[0190] Experiment 4: Microcapsule structure repair ability test

[0191] Purpose of the experiment

[0192] The structural repair ability of the microcapsules imparted by the dynamic cross-linking network of the present invention was evaluated to verify the self-repair effect after the microcapsule structure was damaged.

[0193] Experimental Materials

[0194] The eye protection composition containing a dynamic cross-linked network prepared by the present invention (experimental group);

[0195] an eye protection composition prepared by a traditional chemical cross-linking method (control group 1);

[0196] an eye protection composition that was not cross-linked (control group 2);

[0197] Ultrasonic crusher;

[0198] Laser confocal microscopy;

[0199] fluorescent labeling reagents (FITC, fluorescein isothiocyanate);

[0200] microsyringes and microtiter plates;

[0201] Fluorescence spectrophotometer.

[0202] Experimental methods

[0203] Microcapsule structure damage induction:

[0204] The microcapsule samples of the experimental group, control group 1, and control group 2 were treated with ultrasound (power 40 W, intermittent ultrasound for 20 seconds) to cause mild structural damage;

[0205] Laser confocal microscopy was used to observe the morphological changes of microcapsules before and after ultrasonic treatment;

[0206] The percentage of structurally intact microcapsules in each group of samples was calculated;

[0207] Dynamic observation of structural repair:

[0208] After ultrasonic treatment, each group of samples was incubated in an environment of 37°C and 75% relative humidity;

[0209] Samples were taken at 0 h, 2 h, 6 h, 12 h, and 24 h, and the changes in microcapsule structure were observed using a laser confocal microscope;

[0210] The percentage of microcapsules with intact structures at each time point was calculated;

[0211] Leakage rate determination:

[0212] The active ingredients in the microcapsules were fluorescently labeled with FITC;

[0213] Each group of labeled microcapsule samples was treated with ultrasound and then placed in PBS buffer;

[0214] The fluorescence intensity in the supernatant was measured at 0 h, 2 h, 6 h, 12 h, and 24 h, and the leakage rate of the active ingredient was calculated;

[0215] Each test was repeated 3 times and the average value was taken.

[0216] Experimental results

[0217] Table 4-1. Microcapsule structural integrity before and after ultrasonic treatment (%)

[0218]

[0219] Table 4-2. Microcapsule structural integrity rate (%) at different repair times

[0220]

[0221] Table 4-3. Active ingredient leakage rate (%) at different repair times

[0222]

[0223] From Table 4-1, Table 4-2 and Table 4-3 we can see that:

[0224] Structural repair ability: 24 hours after ultrasound damage, the structural integrity of the microcapsules prepared by the present invention (experimental group) increased from an initial 65.3% to 88.7%, with a repair rate of 71.8% ((88.7-65.3) / (100-65.3)×100%). In contrast, the structural integrity of microcapsules prepared by traditional chemical cross-linking methods (control group 1) remained essentially unchanged after damage (68.5% to 68.7%), while that of microcapsules not cross-linked (control group 2) continued to decrease (from 52.1% to 47.5%).

[0225] Active ingredient leakage control: During the repair process, the active ingredient leakage rate in the experimental group decreased from an initial 22.5% to 8.3%, indicating that the repair of the microcapsule wall material effectively prevented further leakage of the active ingredient. In contrast, the leakage rate in control group 1 remained largely stable, while that in control group 2 increased from 35.6% to 52.1%, indicating that the non-cross-linked microcapsules continued to deteriorate after damage.

[0226] The above results prove that the present invention successfully gives the microcapsule structure the ability to repair by introducing an enzymatic directional cross-linking system and a dynamic cross-linking network. When the microcapsule structure is slightly damaged, the remaining active enzyme can continue to catalyze the cross-linking reaction to repair structural defects, significantly improving the stability and durability of the product under various application conditions. This is of great significance for the long-term effectiveness of eye protection products in actual use.

[0227] Experiment 5: Bioavailability Test

[0228] Purpose of the experiment

[0229] The bioavailability of the nanoscale fibrous microcapsule network prepared by the present invention after topical ocular application was evaluated and compared with that of traditional microcapsule preparations.

[0230] Experimental Materials

[0231] The eye protection composition prepared by the electrospinning technology of the present invention (experimental group A);

[0232] A microcapsule eye protection composition prepared by conventional spray drying technology (control group B);

[0233] a mixture of non-microencapsulated eye protection active ingredients (Control C);

[0234] In vitro corneal permeability model (a three-dimensional cell model constructed using the corneal epithelial cell line HCE-T);

[0235] Isolated porcine cornea;

[0236] fluorescent labeling reagents (FITC, fluorescein isothiocyanate);

[0237] confocal laser scanning microscopy;

[0238] High performance liquid chromatography-mass spectrometry (HPLC-MS / MS);

[0239] Artificial tears (pH 7.4, containing various electrolytes and proteins).

[0240] Experimental methods

[0241] In vitro permeation assay:

[0242] Each group of FITC-labeled samples (active ingredient concentrations were adjusted to the same) were loaded into the upper chamber of the in vitro corneal permeation model;

[0243] Artificial tears were added to the lower chamber as the receiving solution;

[0244] The cells were cultured at 37°C, and samples were taken from the lower chamber at 0.5 h, 1 h, 2 h, 4 h, and 6 h;

[0245] The fluorescence intensity in the receiving solution at each time point was measured using a fluorescence spectrophotometer to calculate the permeation amount;

[0246] Calculate cumulative permeability and permeability coefficient;

[0247] In vitro corneal tissue distribution study:

[0248] Each group of FITC-labeled samples was dropped onto the surface of the isolated pig cornea (20 μL);

[0249] Incubate at 37°C and 95% relative humidity for 2 hours;

[0250] The corneal surface was gently rinsed three times with normal saline to remove unabsorbed sample;

[0251] The distribution of active ingredients at different depths of the cornea was observed using confocal laser scanning microscopy;

[0252] Measure the fluorescence intensity distribution curve to evaluate the tissue penetration depth of active ingredients;

[0253] Active ingredient release kinetics study:

[0254] Each group of samples was placed in artificial tears (the ratio of sample to artificial tears was 1:10);

[0255] The mixture was shaken at 100 rpm at 37°C.

[0256] Samples were collected at 0.5 h, 1 h, 2 h, 4 h, 8 h, 12 h, and 24 h;

[0257] The content of the main active ingredients released into artificial tears was determined using HPLC-MS / MS;

[0258] Draw cumulative release curves and analyze release kinetic parameters;

[0259] Each test was repeated 3 times and the average value was taken.

[0260] Experimental results

[0261] Table 5-1. Cumulative permeability (%) in the in vitro corneal permeation model

[0262]

[0263] Table 5-2. Fluorescence intensity in corneal tissue at different depths (relative units)

[0264]

[0265] Table 5-3. Cumulative release rate in artificial tears (%)

[0266]

[0267] Result Analysis

[0268] From Table 5-1, Table 5-2 and Table 5-3 we can see that:

[0269] In vitro corneal permeability: The eye protection composition prepared by electrospinning technology (experimental group A) achieved a cumulative permeation rate of 32.5% after 6 hours, 68.4% higher than the microcapsule composition prepared by traditional spray drying technology (control group B, 19.3%). The non-microencapsulated active ingredient (control group C), while having a higher initial permeation rate, significantly slowed down in the later stages, resulting in a final cumulative permeation rate (28.2%) lower than that of experimental group A, indicating that experimental group A has more sustained and stable permeation characteristics.

[0270] Corneal Tissue Distribution: Experimental Group A showed significantly better distribution in deep corneal tissue than Control Groups B and C. At a depth of 160 μm, the relative fluorescence intensity of Experimental Group A was 6.3, while that of Control Groups B and C was only 0.2 and 0.3, respectively. This demonstrates that the nanoscale fibrous microcapsule network prepared by the present invention can promote deep penetration and uniform distribution of active ingredients in corneal tissue.

[0271] Active ingredient release kinetics: Experimental Group A demonstrated ideal sustained-release properties, releasing 48.5% of the active ingredient in the first 4 hours and the remaining 44.1% in the subsequent 20 hours, presenting a relatively uniform release curve overall. In contrast, Control Group C released 82.5% of the active ingredient within 2 hours, demonstrating a typical burst release phenomenon. While Control Group B also exhibited some sustained-release properties, its overall release rate was slightly faster than that of Experimental Group A.

[0272] The above results prove that the nanoscale fibrous microcapsule network formed by the electrospinning technology of the present invention has a larger specific surface area and better biocompatibility, which enables the active ingredients to contact the eye tissue more effectively, enhances permeability and distribution uniformity, and at the same time achieves a good sustained-release effect, comprehensively improves the bioavailability of the eye protection active ingredients, and provides more lasting and effective protection for the eyes.

[0273] The above describes an embodiment of the present invention, but this embodiment is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Ordinary technicians in this field can also make more forms of equivalent embodiments based on the inspiration of this embodiment, all of which are protected by this embodiment.

Claims

1. A process for preparing an eye protection composition based on natural extracts, characterized in that: The following steps are involved: Step 1: Mix the natural eye protection active ingredients with carrier oil to form an oil phase mixture; Step 2: Dispersing the oil phase mixture into the inner wall material aqueous solution containing gelatin, gum arabic and sodium alginate to form a water-in-oil emulsion; Step 3: adding at least three natural antioxidants with different modes of action to the emulsion to form an antioxidant synergistic circulation structure; Step 4: adding an enzyme system and a natural cross-linking agent precursor to cause an enzymatic directional cross-linking reaction in the inner wall material; Step 5: constructing an outer wall material composed of polysaccharides to form a double-layer microcapsule structure; Step 6: Perform layer-by-layer infiltration and diffusion treatment to form a gradient distribution of the antioxidant in the microcapsule wall material; Step 7: Mixing the treated double-layer microcapsules with a polyvinyl alcohol aqueous solution and electrospinning them in a low-temperature, oxygen-free environment to obtain a nanoscale fibrous microcapsule network product; The natural eye-protecting active ingredients include capparis spinosa fruit extract, lutein, wild chrysanthemum flower extract and cassia seed extract, which are mixed in a weight ratio of 3:2:2:1; The carrier oil is a mixture of olive oil, evening primrose oil, and linseed oil in a weight ratio of 2:1:1; The three natural antioxidants with different modes of action include: the first type of antioxidant is rosemary extract, added in an amount of 0.5-1.0% by weight of the total oil phase; the second type of antioxidant is green tea extract, added in an amount of 0.8-1.2% by weight of the total aqueous phase; the third type of antioxidant is vitamin E, added in an amount of 0.3-0.6% by weight of the total oil phase; The enzyme system includes horseradish peroxidase and laccase, and the natural cross-linking agent precursor includes tea polyphenols and chitosan oligosaccharides; The outer wall material consists of sodium alginate and low-methoxy pectin, and is formed by ionic cross-linking induced by calcium chloride solution.

2. The process for preparing an eye protection composition based on natural extracts according to claim 1, characterized in that: The enzymatic directional cross-linking reaction is carried out at pH 6.0-6.5 and temperature 25-30° C. for 2-4 hours.

3. The process for preparing the eye protection composition based on natural extracts according to claim 1, characterized in that: The layer-by-layer osmotic diffusion treatment is carried out in an ethanol aqueous solution containing 0.3% rosmarinic acid, 0.5% tea polyphenols and 0.2% tocopherol, with an ethanol content of 30%, a temperature of 25° C., and a treatment time of 4-6 hours.

4. The process for preparing an eye protection composition based on natural extracts according to claim 1, characterized in that: The electrospinning is carried out under the conditions of a high voltage electric field of 15-18 kV, a spinning distance of 15-20 cm and a feed rate of 0.5-1.0 mL / h, with the temperature controlled at 20±2° C. and the relative humidity controlled at 40±5%.

5. An eye protection composition based on natural extracts, characterized in that: The invention is prepared by the preparation process according to any one of claims 1 to 4, comprising a double-walled microcapsule structure and an antioxidant synergistic circulation structure, wherein the inner wall material of the microcapsule contains a variety of natural antioxidants, and the outer wall material of the microcapsule is composed of polysaccharides.

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