Enteromorpha polysaccharide composite sunscreen film, preparation method and application thereof

Abstract

The present application provides a Enteromorpha polysaccharide composite sunscreen film and a preparation method and application thereof. The method comprises the following steps: S1: preparing a nano-spray solution containing Enteromorpha polysaccharide and a spinning solution containing nano-titanium dioxide particles and PVB, respectively; S2: spraying the nano-spray solution to the skin surface in need of sunscreen care through a nano-spray device; S3: electrospinning a titanium dioxide / PVB composite micro-nanofiber film in situ on the skin surface sprayed with the nano-spray solution through an in-situ electrospinning device, the titanium dioxide / PVB composite micro-nanofiber film is compounded with the Enteromorpha polysaccharide on the skin surface, thereby forming the Enteromorpha polysaccharide composite sunscreen film. The obtained sunscreen film has water resistance, dust resistance and biocompatibility, and also has high air permeability and skin adaptability, can effectively avoid the damage of free radicals generated by sunscreen agent titanium dioxide to the skin, can firmly adhere to the skin surface, has long-lasting sun protection, and is easy to remove from the skin, and after removal, there is no residue and the skin is not damaged.

Description

Technical Field

[0001] This invention belongs to the field of cosmetic technology, specifically relating to the Ulva prolifera polysaccharide composite sunscreen film, its preparation method, and its application. Background Technology

[0002] The incidence of skin cancer has risen significantly in recent decades, and public awareness of the potential harm of ultraviolet radiation to skin health has also increased, making sunscreen an indispensable part of daily skin care. Most sunscreens on the market are currently in liquid or cream form and are mostly water-soluble, resulting in insufficient durability under sweat and moisture, while also limiting skin breathability. Furthermore, sunscreen residue may clog skin pores, and its chemical components may cause skin irritation, leading to allergic reactions and accelerated skin aging. Additionally, sunscreen ingredients, such as titanium dioxide, can generate free radicals, causing skin irritation and even phototoxicity.

[0003] To reduce sunscreen usage and improve durability, in-situ electrospinning technology offers a potential solution for preparing nanofiber sunscreen films. In-situ electrospinning technology has demonstrated significant advantages in several fields due to its ease of operation and high degree of directional control. In wound dressings, this technology enables the direct fabrication of nanofiber membranes on skin wounds. Their porous structure provides excellent breathability, helping to maintain the humidity balance of the wound environment, promoting healing, and inhibiting bacterial growth, thus reducing the risk of infection. Our team's previous research has shown that electrospun poly-ε-caprolactone (PCL) nanofibers possess good breathability and excellent biocompatibility, making them suitable for wound dressings. This study also demonstrates a simple method for directly preparing fibrous membranes on human skin using a portable electrospinning device, resulting in membranes with breathability and mechanical properties that match those of human skin.

[0004] However, research on the application of electrospinning technology in sunscreen manufacturing is relatively limited, and its sun protection performance needs further investigation. For example, if commonly used titanium dioxide particles, which have sun protection properties, are directly spun onto the skin surface to form a fiber film through in-situ electrospinning, although theoretically it can provide some sun protection, the free radicals generated by the photocatalytic effect of titanium dioxide can also damage the skin and cause adverse effects. Summary of the Invention

[0005] To address the aforementioned problems, this invention aims to provide a *Ulva prolifera* polysaccharide composite sunscreen film, its preparation method, and its applications. The sunscreen film prepared by this method possesses waterproof, dustproof, and biocompatible properties, as well as high breathability and skin adaptability. It effectively avoids the damage to the skin caused by free radicals catalyzed by the sunscreen agent titanium dioxide. It can firmly adhere to the skin surface, providing long-lasting sun protection, and is easily removed from the skin without leaving any residue or causing skin damage.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The first aspect of this invention discloses a method for preparing a seaweed polysaccharide composite sunscreen film, comprising the following steps:

[0008] S1: Prepare nano spray solutions containing Ulva polysaccharides and spinning solutions containing nano titanium dioxide particles and PVB respectively;

[0009] S2: Apply a nano-spray solution to the skin surface that needs sun protection using a nano-spray device;

[0010] S3: Then, an in-situ electrospinning device is used to electrospin a titanium dioxide / PVB composite micro / nanofiber membrane on the skin surface sprayed with nano-spray solution. The titanium dioxide / PVB composite micro / nanofiber membrane is then combined with the seaweed polysaccharide on the skin surface to form a seaweed polysaccharide composite sunscreen film.

[0011] Preferably, in step S1, the nano-spray solution is an aqueous solution of *Ulva prolifera* polysaccharide, and the content of *Ulva prolifera* polysaccharide in the aqueous solution is 25-50 mg / ml.

[0012] Preferably, the solvent used to prepare the spinning solution includes anhydrous ethanol, and each 10g of spinning solution contains 0.5-1.0g of PVB and 0.025-0.1g of nano-sized titanium dioxide.

[0013] Preferably, in step S1, the spinning solution is prepared by dissolving PVB in anhydrous ethanol and stirring thoroughly at room temperature to obtain a PVB solution. Then, nano-sized titanium dioxide is added to the PVB solution and stirred thoroughly at room temperature. The solution is then ultrasonically treated to remove air bubbles, thus obtaining the spinning solution.

[0014] Preferably, 0.5-1.0g of PVB is dissolved in 9.0-10.0g of anhydrous ethanol and stirred at room temperature for 1-2h to obtain a PVB solution. Then, 0.025-0.1g of nano-titanium dioxide particles are added to 10g of PVB solution and stirred at room temperature for 1-2h. The solution is then sonicated for 10-20min to remove air bubbles to obtain a spinning solution. Ulva prolifera polysaccharide is dissolved in deionized water at a concentration of 25-50mg / ml and stirred for 30min to obtain a nano-spray solution.

[0015] Preferably, the nano-spray device used in step S2 is an electrostatic spray device, with the distance between the nozzle of the electrostatic spray device and the skin set at 10-20cm, the spray voltage at 5-20kV, and the spray time at 100-130s.

[0016] Preferably, in step S3, the distance between the spinning nozzle and the skin is 10-30cm, the spinning voltage is 5-20kV, and the spinning time is 200-300s.

[0017] The second aspect of this invention discloses a seaweed polysaccharide composite sunscreen film prepared by the above-described preparation method.

[0018] Preferably, the average fiber diameter of the sunscreen film is 500±5.8nm.

[0019] Preferably, the contact angle between the sunscreen film and the liquid is greater than 100°.

[0020] Preferably, the tensile strength of the sunscreen film is 1.3-1.8 MPa.

[0021] Preferably, the air permeability of the sunscreen film is ≥60mm / s.

[0022] Preferably, the sunscreen film has an ultraviolet blocking rate of 55-60%, and after soaking, the ultraviolet blocking rate remains at 53-68%. Moreover, after 1 hour of ultraviolet irradiation, the ultraviolet blocking efficiency of the sunscreen film remains the same as before irradiation.

[0023] As a preferred option, the sunscreen film can still maintain more than 80% adhesion after being applied to the skin in situ for 120 minutes.

[0024] The third aspect of this invention discloses the application of the above-mentioned sunscreen film in the field of skin sun protection, such as replacing sunscreen for daily skin sun protection, or for ultraviolet protection in special working environments.

[0025] The beneficial effects of this invention are as follows: It provides a *Ulva prolifera* polysaccharide composite sunscreen film, its preparation method, and its application. The sunscreen film prepared by this method is waterproof, dustproof, and biocompatible, and also has high breathability and skin adaptability. It can effectively avoid the damage to the skin caused by free radicals catalyzed by the sunscreen agent titanium dioxide. It can firmly adhere to the skin surface, providing long-lasting sun protection, and is easily removed from the skin without leaving any residue or causing skin damage. Specifically:

[0026] 1) This method combines in-situ electrostatic technology with nanospray technology. First, a solution of *Ulva prolifera* polysaccharide is sprayed onto the skin area requiring sun protection using a nanospray device. Then, nano-sized titanium dioxide and polyvinyl butyral (PVB) are spun together using an in-situ electrospinning device, allowing them to directly adhere to the sprayed area of ​​the *Ulva prolifera* polysaccharide solution, forming a nanofiber sunscreen film. *Ulva prolifera* polysaccharide can prevent skin damage caused by free radicals generated by the photocatalytic effect of titanium dioxide. Furthermore, compared to directly blending *Ulva prolifera* polysaccharide and titanium dioxide composite fibers, spraying *Ulva prolifera* polysaccharide separately using nanospray technology ensures that the polysaccharide remains on the fiber surface, thus avoiding the influence of the polymer matrix of the electrospun fiber on the release rate of the polysaccharide and improving the free radical scavenging effect of the polysaccharide.

[0027] 2) Combining the excellent waterproofness of PVB as the base material with the outstanding breathability of the electrospun nanofiber membrane, the prepared sunscreen film not only has waterproof, dustproof and biocompatible properties, but also has high breathability and skin adaptability, which can meet the safety requirements of sunscreen products.

[0028] 3) The charge generated during the in-situ electrospinning process helps the nanofibers to adhere to the skin, so that the fiber film of the present invention can adhere firmly to the skin surface and ensure the effect of use. At the same time, since the sunscreen film is only adhered to the skin by physical force (such as van der Waals force), when the sunscreen film needs to be removed, the sunscreen film of the present invention can be easily removed from the skin without leaving any residue, which can effectively avoid the problems of pore blockage and skin irritation.

[0029] 4) The sunscreen film prepared by this method exhibits excellent physical properties: extremely high breathability, hydrophobic angles exceeding 100° for everyday liquid contact, and tensile strength between 1.3 and 1.8 MPa, matching the tensile strength of human skin, allowing it to adhere to the skin and stretch without easily falling off. The UV blocking efficiency of this sunscreen film remains consistent with its initial value after prolonged UV exposure, demonstrating excellent photostability. Furthermore, after immersion in water for 5 mm, the UV blocking efficiency decreases by only about 2%, indicating good water stability. Daily sweating and waterproof environments do not affect its UV protection effect, achieving long-lasting waterproof sun protection. Attached Figure Description

[0030] Figure 1 SEM images and fiber diameter distribution statistics of the fiber materials prepared in the embodiments of the present invention;

[0031] Figure 2 This is a schematic diagram of the statistical results of the liquid contact angle measured in the hydrophobicity test of Example 5;

[0032] Figure 3 The graph shows the fiber tensile properties test results for Example 5;

[0033] Figure 4 This is a graph showing the air permeability test results for Example 5;

[0034] Figure 5 The images shown are fluorescence in vivo imaging photographs and fluorescence intensity change curves from Example 6.

[0035] Figure 6 These are optical microscope images of the skin surface before and after the removal of the sunscreen film in Example 7;

[0036] Figure 7 The graph shows the UV blocking rate test results for Example 8;

[0037] Figure 8 The graph shows the particle barrier rate and pressure drop test results for Example 9;

[0038] Figure 9 This is a diagram showing the cell compatibility assessment results for Example 10;

[0039] Figure 10 The figure shows the results of animal experiments testing the ultraviolet shielding performance of the sunscreen film in Example 11.

[0040] Figure 11 This is a diagram showing the non-invasive and histological evaluation results of the skin on the back of nude mice in the animal experiment of the sunscreen film in Example 11;

[0041] in, Figure 1 A shows the SEM image and fiber diameter distribution statistics of pure PVB fibers. Figure 1 B shows the SEM image and fiber diameter distribution statistics of the titanium dioxide / PVB composite micro / nanofiber membrane from Example 1. Figure 1 C represents the SEM image and fiber diameter distribution statistics of the seaweed polysaccharide composite sunscreen film of Example 1; Figure 2 Figures A to 2C show the initial contact angle test results. Figure 2 Figure A shows the contact angle test results of a pure PVB fiber membrane. Figure 2 Figure B shows the contact angle test results of the titanium dioxide / PVB composite micro / nanofiber membrane. Figure 2 Figure C shows the contact angle test results for the sunscreen film. Figure 2 Figures D to 2F show the contact angle test results measured after immersion in the liquid for 3 minutes. Figure 2 D is the contact angle test result of pure PVB fiber membrane. Figure 2 E represents the contact angle test results of the titanium dioxide / PVB composite micro / nanofiber membrane. Figure 2 Figure showing the contact angle test results of the sunscreen film (F). Figure 5 A is a fluorescence in vivo imaging photograph from Example 6. Figure 5 B represents the fluorescence intensity versus time curve; Figure 6 A is an optical microscope image of the skin surface before the sunscreen was applied. Figure 6 B is an optical microscope image of the skin surface after sunscreen has been applied. Figure 6 C is an optical microscope image of the skin surface after the sunscreen film has been removed; Figure 9 Image A shows the results of live-dead staining of HUVEC cells. Figure 9 B is a statistical graph of HUVEC cell viability. Figure 9 C shows the results of live-dead staining of 3T3 cells. Figure 9 D is a statistical graph of 3T3 cell viability; Figure 10 Image A is a comparison of photographs of the back of a nude mouse. Figure 10 B. Curve showing the change in the degree of skin erythema damage over time. Figure 10 C. Curve showing the change in the degree of skin infiltration damage over time; Figure 10D. Curve showing the change in the degree of skin scaling damage over time; Figure 11 A is a statistical chart of positive area density. Figure 11 B is a statistical chart showing the percentage of collagen area. Figure 11 C is a statistical chart of dermal thickness. Figure 11 D is the result of He staining. Figure 11 E represents the results of Masson staining. Detailed Implementation

[0042] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] A method for preparing a seaweed polysaccharide composite sunscreen film includes the following steps:

[0044] S1: Prepare nano spray solutions containing Ulva polysaccharides and spinning solutions containing nano titanium dioxide particles and PVB respectively;

[0045] S2: Apply a nano-spray solution to the skin surface that needs sun protection using a nano-spray device;

[0046] S3: Then, an in-situ electrospinning device is used to electrospin a titanium dioxide / PVB composite micro / nanofiber membrane on the skin surface sprayed with nano-spray solution. The titanium dioxide / PVB composite micro / nanofiber membrane is then combined with the seaweed polysaccharide on the skin surface to form a seaweed polysaccharide composite sunscreen film.

[0047] In step S1, the nano-spray solution is an aqueous solution of *Ulva prolifera* polysaccharide, with a polysaccharide content of 30 mg / ml. The solvent for preparing the spinning solution includes anhydrous ethanol, and each 10g of spinning solution contains 0.5-1.0g of PVB and 0.025-0.1g of nano-sized titanium dioxide. Specifically, in step S1, the spinning solution is prepared as follows: PVB is dissolved in anhydrous ethanol and stirred thoroughly at room temperature to obtain a PVB solution. Then, nano-sized titanium dioxide is added to the PVB solution and stirred thoroughly at room temperature. The solution is then ultrasonically treated to remove air bubbles, thus obtaining the spinning solution.

[0048] In step S2, the nano-spray device used is an electrostatic spray device. The distance between the nozzle of the electrostatic spray device and the skin is set to 10-20cm, the spray voltage is 5-20kV, and the spray time is 100-130s.

[0049] In step S3, the distance between the spinning nozzle and the skin is 10-30cm, the spinning voltage is 5-20kV, and the spinning time is 200-300s.

[0050] The *Ulva prolifera* polysaccharide composite sunscreen film prepared using the above method has an average fiber diameter of 500±5.8 nm, a contact angle between the sunscreen film and the liquid greater than 100°, and a tensile strength of 1.3-1.8 MPa. The film has an air permeability ≥60 mm / s, an ultraviolet (UV) blocking rate of 55-60%, and maintains a UV blocking rate of 53-68% after immersion. Furthermore, after 1 hour of UV irradiation, the UV blocking efficiency of the sunscreen film remains consistent with that before irradiation.

[0051] The present invention will be further described below with reference to specific embodiments. The raw materials and reagents used in the following embodiments are:

[0052] Polyvinyl butyral (PVB): MW. 90,000-120,000, Macklin;

[0053] Ulva polysaccharide: purchased from Qingdao Ocean University Biotechnology Group (Qingdao, China), purity 95%;

[0054] Example 1

[0055] A method for preparing a seaweed polysaccharide composite sunscreen film includes the following steps:

[0056] S1: Dissolve 0.7g PVB in 9.3g anhydrous ethanol and stir at room temperature for 2h to obtain a PVB solution. Then add 0.1g nano titanium dioxide particles to 10g of PVB solution, stir at room temperature for 2h, and sonicate for 10min to remove bubbles to obtain a spinning solution. Dissolve Ulva prolifera polysaccharide in deionized water at a concentration of 30mg / ml and stir for 30min to obtain a nano-spray solution.

[0057] S2: Add the nano spray solution to the electrostatic spray device, and spray the nano spray solution onto the skin surface that needs sun protection through the electrostatic spray device. The distance between the nozzle of the electrostatic spray device and the skin is set to 10cm, the spray voltage is 15kV, and the spray time is 120s.

[0058] S3: Add the spinning solution to the electrospinning device, and use the in-situ electrospinning device to electrospin a titanium dioxide / PVB composite micro / nanofiber membrane (morphology as shown) on the skin surface sprayed with the nano-spray solution. Figure 1 As shown in Figure B), the distance between the spinning nozzle and the skin is 15cm, the spinning voltage is 10kV, and the spinning time is 300s. The titanium dioxide / PVB composite micro / nanofiber membrane then combines with *Ulva prolifera* polysaccharides on the skin surface, thus forming a *Ulva prolifera* polysaccharide composite sunscreen film (morphology as shown in Figure B). Figure 1 (as shown in C).

[0059] Example 2

[0060] A method for preparing a seaweed polysaccharide composite sunscreen film includes the following steps:

[0061] S1: Dissolve 1.0g PVB in 9.0g anhydrous ethanol and stir at room temperature for 1.5h to obtain a PVB solution. Then add 0.025g nano-titanium dioxide particles to 10g of PVB solution, stir at room temperature for 1.5h, and sonicate for 15min to remove bubbles to obtain a spinning solution. Dissolve Ulva prolifera polysaccharide at a concentration of 25mg / ml in deionized water and stir for 20min to obtain a nano-spray solution.

[0062] S2: Add the nano spray solution to the electrostatic spray device, and spray the nano spray solution onto the skin surface that needs sun protection through the electrostatic spray device. The distance between the nozzle of the electrostatic spray device and the skin is set to 15cm, the spray voltage is 5kV, and the spray time is 100s.

[0063] S3: Add the spinning solution to the electrospinning device, and electrospin a titanium dioxide / PVB composite micro / nanofiber membrane on the skin surface sprayed with nano-spray solution in situ using the in-situ electrospinning device. The distance between the spinning nozzle and the skin is 10cm, the spinning voltage is 5kV, and the spinning time is 200s. The titanium dioxide / PVB composite micro / nanofiber membrane then combines with the seaweed polysaccharide on the skin surface, thereby forming a seaweed polysaccharide composite sunscreen film.

[0064] Example 3

[0065] A method for preparing a seaweed polysaccharide composite sunscreen film includes the following steps:

[0066] S1: Dissolve 0.5g PVB in 9.5g anhydrous ethanol and stir at room temperature for 1h to obtain a PVB solution. Then add 0.05g nano titanium dioxide particles to 10g of PVB solution, stir at room temperature for 1h, and sonicate for 20min to remove bubbles to obtain a spinning solution. Dissolve Ulva prolifera polysaccharide in deionized water at a concentration of 50mg / ml and stir for 30min to obtain a nano-spray solution.

[0067] S2: Add the nano spray solution to the electrostatic spray device, and spray the nano spray solution onto the skin surface that needs sun protection through the electrostatic spray device. The distance between the nozzle of the electrostatic spray device and the skin is set to 20cm, the spray voltage is 20kV, and the spray time is 130s.

[0068] S3: Add the spinning solution to the electrospinning device, and electrospin a titanium dioxide / PVB composite micro / nanofiber membrane on the skin surface sprayed with nano-spray solution in situ using the in-situ electrospinning device. The distance between the spinning nozzle and the skin is 30cm, the spinning voltage is 20kV, and the spinning time is 250s. The titanium dioxide / PVB composite micro / nanofiber membrane then combines with the seaweed polysaccharide on the skin surface, thereby forming a seaweed polysaccharide composite sunscreen film.

[0069] Example 4 Morphology Analysis

[0070] The nanofiber membranes prepared in Example 1 and the morphology of pure PVB fiber membranes formed by electrospinning the PVB solution of Example 1 using the same spinning parameters as in Example 1 were observed using a desktop scanning electron microscope (SEM, Phenom Pro G6, ThermoFiher). The diameter distribution of a total of 50 randomly selected fibers was measured using image analysis software (Nano Measurer 1.2). The experimental results are as follows: Figure 1 As shown.

[0071] like Figure 1 As shown, a pure PVB fiber membrane was examined using a scanning electron microscope. Figure 1 A) Titanium dioxide / PVB composite micro / nanofiber membrane ( Figure 1 B), Ulva polysaccharide composite sunscreen film ( Figure 1 C) The surface morphology of the three electrospun fiber membranes was characterized. It can be seen that the fiber diameter of the pure PVB fiber membrane is approximately 530 nm, while the fiber diameter of the titanium dioxide / PVB composite micro / nanofiber membrane is reduced to approximately 470 nm, and the fiber diameter of the *Ulva prolifera* polysaccharide composite sunscreen membrane is approximately 500 nm. Figure 1 As shown in Figure C, we found that the addition of nano-sized titanium dioxide increased the solution conductivity from 2.6 μS / cm to 13.8 μS / cm. This change played a crucial role in the electrospinning process because the increased conductivity effectively promoted the stretching of the spinning solution, thereby enabling the jet to be finer and ultimately yielding fibers with a smaller diameter. Spraying Ulva prolifera polysaccharide onto the fiber surface via nano-spraying increased the average fiber diameter to some extent. This is due to the adhesion and accumulation of Ulva prolifera polysaccharide on the fiber surface, and also proves that the preparation method of this invention achieves the composite of Ulva prolifera polysaccharide and titanium dioxide / PVB composite micro / nanofiber membrane.

[0072] Example 5 Physical Performance Test

[0073] Hydrophobicity tests were performed on the pure PVB fiber membrane prepared in Example 4, the titanium dioxide / PVB composite micro / nanofiber membrane in Example 1, and the sunscreen film using a contact angle meter (Theta, Biolin Scientific, Sweden) and 2 μl droplets (cola, Sprite, sparkling water, black tea, and water). The experimental results are as follows: Figure 2 As shown. The stress-strain test was conducted using a general-purpose materials testing machine (Instron 5300, USA). The fiber membrane was cut into 10mm × 20mm pieces and stretched at a tensile rate of 20mm / min. The test results are shown below. Figure 3 As shown. Using an air permeability analyzer (FX3300IV, Switzerland), under a constant pressure of 200 Pa, the air permeability of a 20 cm² area was analyzed. 2 The nanofiber sunscreen film underwent a breathability test, and the test results are as follows: Figure 4 As shown.

[0074] The PVB framework of nanofiber sunscreen films is a hydrophobic material. The hydrophobic principle primarily stems from the nonpolar hydrocarbon groups in its molecular structure. These groups give PVB its overall hydrophobicity. The surface roughness of PVB and its interactions with other substances (such as chemical reactions or the formation of special nanostructures) may further enhance its hydrophobic properties. These factors work together to give PVB and its composites excellent hydrophobic characteristics in various applications. For example... Figure 2 As shown in Figures A to F, this study systematically analyzed the contact behavior of three types of nanofiber sunscreen films with five commonly encountered liquids (cola, Sprite, sparkling water, black tea, and water). Figure 2 As shown in Figures A to C, during the initial contact phase, the contact angles between these nanofiber sunscreen films and the liquid all exceed 100°, indicating superior hydrophobic properties. Furthermore, as... Figure 2 As shown in Figures D to F, after three minutes of static observation, the contact angles of these nanofiber sunscreen films remained above 100°, fully verifying their stable hydrophobic properties even after prolonged contact with liquids. While contact angles vary depending on the chemical composition, pH, and surface tension of different liquids, they comprehensively reflect the hydrophobic properties of the sunscreen film under various liquid environments. Sunscreen films with excellent hydrophobic properties effectively prevent erosion by moisture or everyday liquids, thus ensuring long-lasting and stable sun protection.

[0075] like Figure 3As shown, the addition of nano-sized titanium dioxide and the composite of Ulva prolifera polysaccharide have a slight impact on the mechanical properties of the fiber membrane. However, the tensile stress of the three fiber membranes is between 1.3 MPa and 1.8 MPa, which meets the tensile strength requirements of human skin. The sunscreen film of Example 1 exhibits excellent tensile properties, and its Young's modulus is similar to that of human skin. This characteristic allows the sunscreen film to fit more closely to human skin in practical applications, reducing the tightness or restraint that may be caused by excessive material rigidity, thereby greatly improving the wearer's comfort experience.

[0076] like Figure 4 As shown, the breathability of nanofiber sunscreen films was systematically evaluated under a constant pressure test condition of 200 Pa. The results showed that pure PVB had the best breathability, with a breathability velocity of 71.5 mm / s. After adding nano-sized titanium dioxide, the breathability velocity slightly decreased to 70 mm / s, and after compounding with *Ulva prolifera* polysaccharide, the breathability velocity slightly decreased to 65.4 mm / s, all still exhibiting excellent breathability. This superior breathability is attributed to the unique structural characteristics of nanofibers. Through interweaving and lateral connections, nanofibers construct a complex and ordered pore structure, which endows the nanofiber membrane with extremely high porosity. This high porosity allows air molecules to easily pass through the fiber membrane, thus achieving good breathability. This characteristic is particularly crucial in sunscreen applications. While maintaining waterproof performance, nanofiber sunscreen films can effectively expel body moisture, thereby preventing the stuffy feeling caused by moisture accumulation.

[0077] Example 6 Skin Adhesion Test

[0078] Rhodamine B was pre-dissolved in the spinning solution, and the labeled spinning solution was electrospun in situ onto the dorsal skin of nude mice. Before the experiment, the backs of the nude mice were cleaned with ethanol and anesthetized. A sunscreen film was applied to the nude mouse skin using the preparation method described in Example 1. At specific time points (0, 30, 60, and 120 min), real-time imaging technology was used to measure the fluorescence of the dorsal skin to determine the retention of the nanofiber sunscreen film on the dorsal skin and to evaluate the skin adhesion of the sunscreen film on the dorsal skin. The experimental results are as follows: Figure 5 As shown.

[0079] like Figure 5As shown, through precise deposition via in-situ electrospinning, a tight adhesion between the nanofiber membrane and nude mouse skin was observed. In subsequent observations, we meticulously recorded the dynamic data of the fluorescence intensity of the nanofiber membrane over time. The data showed that although the fluorescence intensity decreased to some extent over time, it remained at a high level of over 80% after 120 minutes. This result strongly demonstrates the superior skin adhesion performance of the sunscreen film of this invention. This is because the charge generated during in-situ electrospinning facilitates electrostatic adsorption between the nanofibers and the skin, enhancing the adhesion effect. Secondly, the nanofibers typically have a very small diameter, enabling them to form a microscopic uneven structure on the skin surface. This structure increases the friction between the skin and the nanofibers, thereby improving adhesion.

[0080] Example 7 Removability Test Results

[0081] By testing the removability of the sunscreen film, we can ensure that the product is easy to remove, reducing clogged pores and the potential risks of acne and pimples. Using the preparation method of Example 1, the sunscreen film was prepared on a piece of pigskin (35*35mm). After 1 minute, the sunscreen film was gently rubbed off the pigskin by hand. The morphological characteristics of the pigskin before the sunscreen film was applied (bare pigskin), after the sunscreen film was applied (sunscreen layer on the pigskin), and after the sunscreen film coating was removed were observed using an optical microscope (IX53, Olympus, Japan). The results are as follows: Figure 6 As shown.

[0082] In the sunscreen removal test, given the similarity between pig skin and human skin, we chose pig skin as the experimental model to obtain test results that more closely resemble actual human conditions. After gently rubbing off the sunscreen film from the pig skin, it was observed with the naked eye that there was no obvious sunscreen film covering the surface of the pig skin. To ensure the accuracy and reliability of the results, we conducted a detailed analysis under a microscope. The results are as follows... Figure 6 As shown, even under magnification, no residue of the nanofiber sunscreen film remained on the pigskin surface. This excellent removability is attributed to the unique adhesion mechanism of the sunscreen film of this invention. It primarily forms a non-permanent, interconnected solid structure with the skin surface through van der Waals forces. This structure allows the nanofiber sunscreen film to adhere closely to the skin when needed, providing long-lasting and effective sun protection; simultaneously, it can be easily peeled off from the skin surface without leaving any residue when needed. Therefore, for those who are particularly sensitive to the chemicals that may remain in traditional sunscreens, the sunscreen film of this invention undoubtedly provides a safe and effective alternative. It not only meets their needs for sun protection but also effectively avoids the residue problems that may arise from traditional sunscreen films, allowing the skin to enjoy the sun while maintaining a healthy and comfortable state.

[0083] Example 8: Ultraviolet blocking rate test

[0084] The UV transmittance of the pure PVB fiber membrane prepared in Example 4, the titanium dioxide / PVB composite micro / nanofiber membrane (PVB-TiO2) of Example 1, the sunscreen film (PVB-TiO2-EPPs), the PVB-TiO2-EPPs treated with 365nm UV irradiation, and the PVB-TiO2-EPPs with a water-wetted surface were measured at 1nm intervals in the wavelength range of 240nm to 400nm using a diffuse reflectance UV-Visible / NIR Spectrophotometer (UH4150, Japan). The UV transmittance was measured at four points for each sample, and the average value was used. The test results are as follows: Figure 7 As shown.

[0085] The ultraviolet (UV) band from 240nm to 400nm mainly includes medium-wave UV and long-wave UV, which are harmful to the human body. For example... Figure 7 As shown, in the 240nm to 400nm wavelength range, the UV blocking efficiency of pure PVB is between 55% and 60%, and this efficiency shows a slight decreasing trend with increasing wavelength. When nano-sized TiO2 is introduced into the PVB matrix, the UV blocking performance is significantly enhanced, especially in the mid-wave UV region (240nm to 330nm). This is mainly because nano-TiO2 has strong absorption of mid-wave UV radiation, primarily achieving UV blocking through absorption. However, in the long-wave UV region (330nm to 400nm), although the blocking effect is somewhat weaker than in the mid-wave region, its UV blocking performance is still significantly improved compared to pure PVB. The UV blocking rate of PVB-TiO2-EPPs shows that the polysaccharides from *Ulva prolifera* have virtually no effect on the basic UV blocking rate.

[0086] like Figure 7 As shown, after testing the PVB-TiO2-EPPs nanofiber sunscreen film under 365nm UV irradiation for 1 hour, the results showed that its UV blocking rate remained essentially the same as before irradiation, with only a slight decrease observed. This result indicates that the sunscreen film possesses excellent photostability. Furthermore, to evaluate the water stability of the PVB-TiO2-EPPs nanofiber sunscreen film, we immersed the fiber film in water for 5 minutes. The test results showed that its UV blocking rate decreased by only about 2%, a small change that further verifies the stability of the sunscreen film in aquatic environments. Traditional sunscreen films often experience a significant decrease in UV protection performance when exposed to water or sweat, thus limiting their effectiveness in practical applications. However, the PVB-TiO2-EPPs nanofiber sunscreen film maintains a high UV blocking rate while preserving water stability.

[0087] Example 9 Particulate Matter Barrier Efficiency Test

[0088] The fine particulate matter blocking efficiency of nanofiber sunscreen films and N95 masks was tested using a PALAS MFP3000 filter material testing platform. The effective area used in the test was 100cm². 2 The dust generator disperses a 10% KCl solution into tens of thousands of particles of varying sizes. These solid KCl particles are then fed into the test filter via an atomizer using an air pump at a pre-designed airflow velocity (20 cm / s). The average diameter of the particles ranges from 0.225 to 10 micrometers. To evaluate the filter's filtration efficiency, two laser particle counters were used to measure the number of particles upstream and downstream of the filter, respectively; simultaneously, a differential pressure sensor was used to measure the pressure difference across the filter to assess the pressure drop. The experimental results are as follows: Figure 8 As shown.

[0089] PM2.5 can enter the skin through pores. When PM2.5 accumulates on the skin, it can clog pores, sebaceous gland ducts, and hair follicles, affecting normal skin metabolism and triggering skin problems such as acne, blackheads, and pimples. Figure 8 As shown, the PVB-TiO2-EPPs nanofiber sunscreen membrane prepared in this study exhibits excellent filtration efficiency for PM1.0, achieving over 99% filtration efficiency compared to the widely accepted N95 mask. However, when comparing the pressure drop data, we observed that the nanofiber sunscreen membrane showed a lower pressure drop value (115 Pa), significantly lower than the 205 Pa of the N95 mask. This data indicates that the nanofiber sunscreen membrane maintains superior filtration performance while also offering better breathability than the N95 mask.

[0090] Example 10 Cell compatibility experiment

[0091] 10.1 Cell seeding, culture and characterization

[0092] First, human umbilical vein endothelial cells (HUVEC, Cell Membrane, Chinese Academy of Sciences, China) and mouse embryonic fibroblasts (NIH-3T3, Cell Membrane, Chinese Academy of Sciences, China) were cultured in GIBCO high-glucose DMEM complete medium. The medium contained 10% (v / v) fetal bovine serum (FBS) and penicillin / streptomycin (PS) (1%). The cells were divided into four groups (control, PVB (Example 4), PVB-TiO2 (Example 1), and PVB-TiO2-EPP (Example 1)). Then, under aseptic conditions, the above materials were co-cultured in a 5% concentration C2 incubator at 37°C, with the cell culture medium changed periodically. When the cell density reached 80-90%, the cells were digested with trypsin and seeded (at a density of 1 × 10⁴ cells) into 96-well plates.

[0093] To assess cell viability and proliferation of human umbilical vein endothelial cells (HUVECs) and mouse embryonic fibroblasts (NIH-3T3), we used the Cell Counting Kit-8 (CCK-8) on days 1, 3, and 7 of co-culture. The procedure was as follows: The corresponding 96-well cell culture plates were removed from the incubator, the old culture medium and materials were discarded, and the plates were washed three times with phosphate-buffered saline (PBS). 100 μl of fresh complete culture medium and 10 μl of CCK-8 reagent were added to each well under dark conditions. The 96-well cell culture plates were incubated at 37°C in a humid atmosphere with 5% CO2 for 2 hours in the dark. Afterward, 80 μl of the incubated liquid from each well was transferred to a new 96-well cell culture plate, and the absorbance (OD) of each well was measured at 450 nm using a microplate reader. The OD values ​​were measured on days 3 and 7 using the same method. The OD values ​​for the three days were summarized, and the changes in OD values ​​over time were plotted.

[0094] The formula for calculating cell viability is as follows: Cell viability (%) = (Experimental group / Blank control) × 100%.

[0095] 10.2 Cell viability and live / dead staining

[0096] This embodiment uses a live / dead cell viability assay kit (Yeasen Biotechnology (Shanghai)) to determine cell viability. Live cells are labeled with calcein AM, while dead cells are labeled with propidium iodide (PI). Live cells appear green, and dead cells appear red.

[0097] First, take out Calcein AM Solution and PI Solution, equilibrate at room temperature for 30 min, then add 5 μl of PI Solution and 5 μl of Calcein AM Solution to 10 ml of PBS, vortex to prepare a working solution (at this point, the concentration of Calcein AM is 2 μm and the concentration of PI is 8 μm). Then, stain human umbilical vein endothelial cells (HUVEC) and mouse embryonic fibroblasts (NIH-3T3). Then, centrifuge at 1,000 rpm for 3 min using a high-speed centrifuge (Meng'an Instrument Equipment Co., Ltd. (Jiangsu)) to collect cells (10⁴-10⁵ cells). After centrifugation, remove the supernatant and wash 2-3 times with PBS to ensure the removal of active esterases in the culture medium. Then, stain the human umbilical vein endothelial cells (HUVEC) and mouse embryonic fibroblasts (NIH-3T3) with 100 μl of staining working solution and incubate at 37°C for 15-30 min.

[0098] Add an appropriate amount of stained cell solution to a clean glass slide and cover with a coverslip. Seal with nail polish to prevent moisture evaporation. Simultaneously observe live cells (yellow-green fluorescence) and dead cells (red fluorescence) under a Zeiss fluorescence microscope (Aono Optical Technology Co., Ltd. (Shenzhen)) at an excitation wavelength of 490±10 nm. Also observe dead cells separately using an excitation wavelength of 545 nm. Quantitatively analyze live and dead cells after 24 h of exposure to PVB, PVB-TiO2, and PVB-TiO2-EPP elution solutions using ImageJ software. Report the average of three results.

[0099] Experimental results are as follows Figure 9 As shown, HUVEC cells (human umbilical vein endothelial cells) and 3T3 cells (mouse embryonic fibroblasts) are commonly used cell models, representing vascular endothelial cells and fibroblasts, respectively, and can simulate the potential effects of sunscreen films on skin blood vessels and interstitial tissue. Therefore, using these two cell types for sunscreen film cell compatibility testing allows for a more comprehensive assessment of the potential effects of sunscreen films on skin cells. Figure 9 As shown, after adding PVB, PVB-TiO2, and PVB-TiO2-EPPs, there was no significant difference in cell viability compared with the control group, indicating that the nanofiber sunscreen film has good biocompatibility.

[0100] Example 11 Skin Sunscreen Efficacy Experiment

[0101] All animal experiments were conducted in accordance with the experimental animal protocol approved by the Ethics Committee of Qingdao University and relevant laws and guidelines of Qingdao University. Female BALB / c nude mice (8 weeks old) with an average initial weight of 200g were purchased from Spiefol (Beijing) Biotechnology Co., Ltd. The nude mice were housed in an SPF-grade animal facility and under special pathogen-free conditions, receiving a week of acclimatization feeding with a sterile diet and water. Nude mice were then randomly divided into four groups (blank control group, UV irradiation group, PVB-TiO2 + UV irradiation group (PVB-TiO2 fiber membrane was prepared on nude mouse skin according to the method in Example 1, step S2 was omitted in the preparation process), and PVB-TiO2-EPPs + UV irradiation group (PVB-TiO2-EPPs fiber membrane was prepared on nude mouse skin according to the method in Example 1, i.e., the sunscreen membrane in Example 1), with 4 mice in each group, and an anti-UV evaluation experiment was conducted for 4 days. In short, the mice were anesthetized and their dorsal skin was cleaned with 75% alcohol, and then the dorsal epidermis of these mice was treated differently. The irradiation height was 12 cm, the irradiation area was 2 cm × 3 cm, the UV irradiation intensity was 1.00 mW cm⁻², the single UV irradiation dose was 600 mJ cm⁻², and the total UV irradiation dose was 2400 mJ after 4 consecutive days of irradiation. cm-2. The skin condition of each group of nude mice was observed by photographs before and after each irradiation, and relevant indicators were scored (scoring criteria are shown in the table below). After the last drug intervention and ultraviolet irradiation, the nude mice in each group were sacrificed, and the skin tissue of the nude mice was taken for HE, Masson, and immunohistochemical (COX-2) staining to evaluate the skin pathology of each group of nude mice.

[0102] The scoring criteria for erythema, infiltration, and scaling of the back skin in skin injuries are shown in the table below:

[0103]

[0104] See test results Figures 10 to 11 Among them, the UV shielding performance of sunscreen film is as follows: Figure 10 As shown, Figure 10A. Daily photographs and records were taken of the back skin of nude mice. On the first day of UV irradiation, mild erythema was observed on the back skin of both the PVB-TiO2 UV irradiation group and the UVB group, indicating that both groups were mildly affected by UV radiation. Meanwhile, the skin of the nude mice in the blank control group and the PVB-TiO2-EPPs UV irradiation group remained its natural flesh color without significant change. On the second day, the erythema on the skin of the nude mice in the UVB group significantly worsened, showing the cumulative effect of UV damage to the skin. In contrast, the erythema in the PVB-TiO2 UV irradiation group remained mild, while the PVB-TiO2-EPPs UV irradiation group continued to maintain healthy skin, with no erythema or other abnormal changes observed. On the third day, the erythema in the UVB group further deteriorated, showing signs of gradual darkening, possibly due to pigmentation resulting from severe skin damage. While the PVB-TiO2 UV irradiation group maintained mild erythema, no significant change was observed compared to the previous two days. The PVB-TiO2-EPPs UV irradiation group maintained healthy skin. On the fourth day, the erythema and pigmentation in the UVB group became increasingly severe, indicating continued and serious damage to the skin from ultraviolet radiation. Although the erythema in the PVB-TiO2 UV irradiation group remained mild, it did not show significant improvement compared to the previous days. The skin condition of the PVB-TiO2-EPPs UV irradiation group remained healthy. In addition, the skin of the blank control group remained healthy flesh-colored throughout the experiment. No infiltration or scaling reactions were observed in any of the four animal groups during the experiment. Therefore, the sunscreen film (PVB-TiO2-EPPs) of this embodiment can provide better sun protection.

[0105] Before artificial intervention and UVB irradiation, skin barrier function in nude mice was measured daily using a non-invasive assessment method. Erythema, scaling, and infiltration are typically key parameters for assessing UV-related skin damage. Prior to the experiment, erythema, scaling, and infiltration were independently scored daily using a semi-quantitative rating scale (0-4). Figure 10 Figures B to D show the results of erythema, infiltration, and scaling tests, respectively. In the UV irradiation group, these scores significantly increased from 0 to 3-4 in the first four days, indicating the successful establishment of the acute photodamage model. Under UV irradiation conditions, the PVB-TiO2 nanofiber sunscreen film experimental group maintained a score of 1, indicating that the PVB-TiO2 nanofiber sunscreen film provided good sun protection, but still caused some skin damage, leaving room for improvement. In contrast, the PVB-TiO2-EPPs nanofiber sunscreen film experimental group consistently showed an excellent score of 0, a result significantly better than the PVB-TiO2 group, fully demonstrating its superior protective ability against skin damage and highlighting the protective effect of spraying with *Ulva prolifera* polysaccharides on the skin.

[0106] Non-invasive and histological evaluation results of the back skin are as follows: Figure 11 As shown, Figure 11 C shows that at the end of the experiment, skin samples (1cm × 1cm) were collected from the backs of nude mice, and the thickness was measured using calipers. The average thickness of normal skin in the untreated control group was 180.47 mm. However, after high-dose UVB irradiation, the skin in the UV-irradiated group was significantly thinner, with a thickness of approximately 117.52 μm. This is because ultraviolet radiation can damage collagen and elastin fibers in the skin (see...). Figure 11 A and Figure 11 (B) These are important components for maintaining skin thickness and elasticity. When the normal structure of the skin is disrupted, the skin becomes thinner. After intervention with PVB-TiO2 nanofiber sunscreen film and PVB-TiO2-EPPs nanofiber sunscreen film, the skin thickness was 143.15 μm and 154.14 μm, respectively, significantly better than the UVB group (*****P<0.005). The results confirm that PVB-TiO2 nanofiber sunscreen film and PVB-TiO2-EPPs nanofiber sunscreen film effectively inhibit UVB-induced skin thinning. Furthermore, it is evident that the sunscreen film (PVB-TiO2-EPPs nanofiber sunscreen film) in this embodiment is more effective than the PVB-TiO2 nanofiber film. This is attributed to the fact that *Ulva prolifera* polysaccharide, as an antioxidant, can eliminate free radicals generated by TiO2 photocatalysis and stimulate the skin's self-repair ability, promoting the regeneration and repair of damaged skin cells. This is highly beneficial for resisting skin damage and aging caused by ultraviolet radiation.

[0107] like Figure 11 As shown in Figure D, histological sections of back skin tissue were stained with hematoxylin and eosin to observe damage to the epidermis and dermis. In the blank control group, a regular stratum corneum, epidermis, and orderly arranged fibers were observed in the dermis. However, in the UV irradiation group, the dermis was thinner, with a reduced number of collagen fibers and a looser arrangement. Compared with the UV irradiation group, the dermis thickness and the number of sebaceous and sweat glands in the PVB-TiO2 group and the PVB-TiO2-EPPs group were increased, and their structure was similar to that of normal skin. In addition, immunohistochemical staining showed a significant reduction in the positive area of ​​COX-2 overexpression after UVB irradiation (UVB group) and in the PVB-TiO2-EPPs group (see Figure D). Figure 11 D). Histopathological and immunohistochemical analyses both confirmed that the PVB-TiO2-EPPs group exhibited excellent protective performance against UV-induced damage.

[0108] Meanwhile, Masson's trichrome staining is also used to evaluate the UV protection capability of sunscreen films. For example... Figure 11As shown in Figure E, the collagen fibers in the control group were wavy, uniform in thickness, and tightly packed, reflecting the healthy state of normal skin tissue. In the UVB group, the number of collagen fibers decreased, and they were broken and discontinuous. The fiber diameter became thinner, the arrangement loose and disordered, and the gaps widened. These changes indicate that UVB irradiation caused significant damage to the skin's collagen fibers. Compared to the UVB group, the PVB-TiO2 group and the PVB-TiO2-EPPs group showed an increase in the number of collagen fibers, a thicker diameter, and a more orderly and compact arrangement. The experimental results show that the collagen fiber content of the skin treated in the PVB-TiO2-EPPs group was closer to that of the control group, indicating that the sunscreen film of this embodiment has a more significant effect in resisting UVB damage.

[0109] The above experiments demonstrate that the sunscreen film prepared by the method of this embodiment exhibits excellent physical properties, including high cell compatibility, breathability, hydrophobicity, and tensile strength. After continuous ultraviolet (UV) irradiation, the UV blocking efficiency of the sunscreen film remains consistent with that before irradiation, exhibiting excellent photostability. Furthermore, after immersion in water, the UV blocking efficiency decreases by only about 2%, demonstrating good water stability. The sunscreen film maintains over 80% adhesion even after prolonged application to the skin and is easy to remove without leaving any residue, effectively preventing pore blockage and skin irritation.

[0110] The above description is merely an embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the technical solution of the present invention shall still fall within the protection scope of the technical solution of the present invention.

Claims

1. A preparation method of Enteromorpha polysaccharide composite sunscreen film, characterized in that, Includes the following steps: S1: Prepare a nano-spray solution containing *Ulva prolifera* polysaccharide and a spinning solution containing nano-titanium dioxide particles and PVB. The nano-spray solution is an aqueous solution of *Ulva prolifera* polysaccharide, and the content of *Ulva prolifera* polysaccharide in the aqueous solution is 25-50 mg / ml. The solvent for preparing the spinning solution includes anhydrous ethanol, and each 10g of spinning solution contains 0.5-1.0g of PVB and 0.025-0.1g of nano-sized titanium dioxide. S2: Apply a nano-spray solution to the skin surface requiring sun protection using a nano-spray device. S3: Then, an in-situ electrospinning device is used to electrospin a titanium dioxide / PVB composite micro / nanofiber membrane on the skin surface sprayed with nano-spray solution. The titanium dioxide / PVB composite micro / nanofiber membrane is then combined with the seaweed polysaccharide on the skin surface to form a seaweed polysaccharide composite sunscreen film.

2. The production method according to claim 1, characterized by, In step S1, the spinning solution is prepared by dissolving PVB in anhydrous ethanol and stirring thoroughly at room temperature to obtain a PVB solution. Then, nano-sized titanium dioxide is added to the PVB solution and stirred thoroughly at room temperature. The solution is then ultrasonically treated to remove air bubbles, thus obtaining the spinning solution.

3. The preparation method according to claim 2, characterized in that, Step S1 includes: dissolving 0.5-1.0 g of PVB in 9.0-10.0 g of anhydrous ethanol and stirring at room temperature for 1-2 h to obtain a PVB solution; then adding 0.025-0.1 g of nano-titanium dioxide particles to 10 g of the PVB solution and stirring at room temperature for 1-2 h; and sonicating for 10-20 min to remove air bubbles to obtain a spinning solution; and dissolving Ulva prolifera polysaccharide at a concentration of 25-50 mg / ml in deionized water and stirring for 10-30 min to obtain a nano-spray solution.

4. The preparation method according to claim 1, characterized in that, The nano-spray device used in step S2 is an electrostatic spray device. The distance between the nozzle of the electrostatic spray device and the skin is set to 10-20cm, the spray voltage is 5-20kV, and the spray time is 100-130s.

5. The preparation method according to claim 1, characterized in that, In step S3, the distance between the spinning nozzle and the skin is 10-30 cm, the spinning voltage is 5-20 kV, and the spinning time is 200-300 s.

6. A seaweed polysaccharide composite sunscreen film, characterized in that, It is prepared by any one of claims 1 to 5.

7. The sunscreen film as described in claim 6, characterized in that, The average diameter of the fibers in the sunscreen film is 500±5.8nm.

8. The sunscreen film as described in claim 7, characterized in that, The contact angle between the sunscreen film and the liquid is greater than 100°; the tensile strength of the sunscreen film is 1.3-1.8MPa; the air permeability of the sunscreen film is ≥60mm / s; the ultraviolet blocking rate of the sunscreen film is 55-60%, and after soaking, the ultraviolet blocking rate remains at 53-68%, and after 1 hour of ultraviolet irradiation, the ultraviolet blocking efficiency of the sunscreen film remains the same as before irradiation. Even after the sunscreen film has been in situ loaded onto the skin for 120 minutes, it still maintains more than 80% of its adhesion.

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