Sun-screening agent based on hydroxyapatite microspheres and preparation method thereof

Abstract

The invention belongs to the technical field of sunscreen cosmetics, and particularly relates to a sunscreen agent based on hydroxyapatite microspheres and a preparation method of the sunscreen agent. The sun-screening agent based on the hydroxyapatite microspheres is prepared from the following components in percentage by mass: 13 percent to 26 percent of water-soluble chitosan, 40 percent to 43 percent of the hydroxyapatite microspheres and 34 percent to 44 percent of a freeze-drying protective agent. The sun-screening agent can act on the skin epidermis through introduction, is different from a traditional sun-screening agent which is only simply smeared to maintain the sun-screening effect of one day or several days, and the long-acting sun-screening agent based on the hydroxyapatite microspheres can stay on the skin epidermis for a long time to achieve the effects of absorbing and reflecting UVB, so that the sun-screening effect is achieved until the sun-screening agent is completely degraded.

Description

Technical Field

[0001] This invention belongs to the field of sunscreen cosmetics technology, specifically relating to sunscreen agents based on hydroxyapatite microspheres and their preparation methods. Background Technology

[0002] Prolonged exposure to ultraviolet (UV) radiation is a contributing factor to various skin diseases. UV radiation comprises a wavelength spectrum from approximately 100 nm to 400 nm, further divided into UVC (100-280 nm), UVB (280-320 nm), and UVA (320-400 nm). UVA has a long wavelength and low energy but strong penetrating power, reaching deep into the dermis and is a major cause of skin aging, sagging, and wrinkles. UVB can partially penetrate the ozone layer and primarily affects the epidermis, causing significant DNA and RNA damage. Due to its shorter wavelength, UVB radiation can also lead to skin problems such as erythema and sunburn. Erythema, swelling, and delayed tanning in sun-exposed areas are mainly caused by UVB; UVB is the primary culprit behind skin tanning. Therefore, sun protection primarily aims to prevent UVB damage to our skin.

[0003] In the current environment, traditional sunscreen products have many limitations. Sunscreen development primarily focuses on protecting the skin from harmful ultraviolet (UV) radiation (UVA / UVB), neglecting several issues, such as insufficient durability. Traditional organic sunscreens (such as avobenzone and octocrylene) are prone to photodegradation, while inorganic sunscreens (such as titanium dioxide and zinc oxide) are easily shed due to sweating and friction, leading to a rapid decrease in the Sun Protection Factor (SPF). Therefore, there is an urgent need for a long-lasting sunscreen that can effectively absorb and reflect UVB rays at the epidermal layer. Summary of the Invention

[0004] The purpose of this invention is to provide a sunscreen agent based on hydroxyapatite microspheres and its preparation method, thereby solving at least one of the aforementioned technical problems. The sunscreen agent based on hydroxyapatite microspheres provided by this invention can act on and remain in the epidermal layer to provide long-lasting absorption and reflection of UVB rays damaging the skin. In addition to long-lasting sun protection, it also exhibits gradient biodegradability, dual and continuous promotion of collagen production, tissue damage repair, and tissue filling properties. Through the dual action of the carrier material water-soluble chitosan and hydroxyapatite microspheres, it can stimulate macrophages to promote collagen production by fibroblasts, thereby promoting the repair of damaged tissues. Furthermore, it can be biodegraded into non-toxic and harmless small molecules through metabolism within the body.

[0005] According to a first aspect of the invention, a sunscreen based on hydroxyapatite microspheres is provided, comprising, by weight percentage, 13% to 26% water-soluble chitosan, 40% to 43% hydroxyapatite microspheres, and 34% to 44% lyophilization protectant, wherein the water-soluble chitosan endotoxin does not exceed 0.05 EU / mg.

[0006] In some embodiments, water-soluble chitosan requires pretreatment according to the following steps before use: (1) all utensils and instruments that come into contact with water-soluble chitosan are rinsed with 0.5~2.5mol / L NaOH; (2) water-soluble chitosan is dissolved in 1mol / L NaOH and filtered using an ultrafiltration screen; (3) the solution is replaced with new 0.5~2.5mol / L NaOH and soaked for 28-35 days, with the solution replaced every 6-8 days, and filtered using an ultrafiltration screen; (4) the solution is rinsed with water for injection, repeated 5-10 times until the pH value reaches 6.5~7.5; (5) sterilization. Thus, after this pretreatment step, the endotoxin content of the water-soluble chitosan does not exceed 0.05eu / mg, achieving the purpose of endotoxin removal.

[0007] In some embodiments, the water-soluble chitosan includes carboxymethyl chitosan and hydroxybutyl chitosan, wherein the mass ratio of carboxymethyl chitosan to hydroxybutyl chitosan is 3:1 to 1:3.

[0008] In some embodiments, the degree of carboxymethyl substitution in carboxymethyl chitosan is 20-30%, and the degree of deacetylation is 85-95%, while the degree of hydroxybutyl substitution in hydroxybutyl chitosan is 15-25%, and the degree of deacetylation is 85-95%.

[0009] In some embodiments, carboxymethyl chitosan and hydroxybutyl chitosan require pretreatment according to the following steps before use: (1) all utensils and equipment in contact with the material are rinsed with 0.5~2.5mol / L NaOH; (2) carboxymethyl chitosan and hydroxybutyl chitosan are dissolved in 1mol / L NaOH and filtered using a 0.22um ultrafiltration screen; (3) the material is soaked in a new 0.5~2.5mol / L NaOH solution for 28-35 days, and the solution is replaced every 6-8 days, and filtered using a 0.22um ultrafiltration screen; (4) the material is rinsed with water for injection, repeated 5-10 times, until the pH value reaches 6.5~7.5; (5) finally, it is sterilized by wet sterilization at 121℃ for 35-45 minutes. This ensures that the endotoxin content of the final carboxymethyl chitosan and hydroxybutyl chitosan does not exceed 0.05eu / mg.

[0010] In some embodiments, the hydroxyapatite microspheres include one or both of smooth hydroxyapatite microspheres and porous hydroxyapatite microspheres, wherein the porosity of the porous hydroxyapatite microspheres is 20% to 50%.

[0011] In some embodiments, the total Ca and Zn content of the hydroxyapatite microspheres is maintained at 28-35 mmol, the Ca:Zn atomic ratio is 7:2-7:4, the Ca:P molar ratio is 1.66≤Ca / P≤1.71, and the tap density is 0.6-1.0 g / cm³. 3 .

[0012] In some embodiments, the particle size of the hydroxyapatite microspheres is in two gradient ranges: 5 μm to 10 μm and 10 μm to 25 μm, and the mass ratio of the microspheres in the two particle size gradient ranges is 2:1 to 1:1.

[0013] In some embodiments, hydroxyapatite microspheres are obtained by the following preparation method: (1) Ca(OH)2, H3PO4 and Zn(NO3)2 are added to purified water, stirred and dissolved, and the resulting solution is aged; (2) the feed liquid is spray-dried, the resulting droplets are dispersed in the drying chamber, and the particles are collected; (3) the spray-dried hydroxyapatite particles are ball-milled without adding milling beads; (4) the collected hydroxyapatite microspheres are sintered to obtain hydroxyapatite microspheres. The spray drying parameters are: inlet temperature of 200~220℃, peristaltic pump speed of 13~16 rpm; the ball milling parameters are: rotation speed of 250~350 rpm, and time of 20h~24h.

[0014] In some embodiments, the mass ratio of Ca(OH)2, H3PO4, Zn(NO3)2, and purified water is (1.25~1.30):1:(0.92~1.89):(30~100).

[0015] In some embodiments, hydroxyapatite smooth microspheres are obtained by the following preparation method: (1) Ca(OH)2, H3PO4 and Zn(NO3)2 are added to purified water, and the resulting solution is aged after stirring and dissolving; (2) the aged solution is spray-dried, and the resulting droplets are dispersed in a drying chamber and the particles are collected; (3) the spray-dried hydroxyapatite particles are ball-milled without adding grinding beads; (4) the collected hydroxyapatite microspheres are sintered at an initial temperature of 50°C, a heating rate of 5~7°C / min, a heating time of 230 min, an ending temperature of 1150~1250°C, and a holding time of 30~50 min to obtain hydroxyapatite smooth microspheres. Among them, the spray drying parameters are: inlet temperature of 200~220°C, peristaltic pump speed of 13~16 rpm; the ball milling parameters are: rotation speed of 250~350 rpm, and time of 20h~24h.

[0016] In some embodiments, porous hydroxyapatite microspheres are obtained by the following preparation method: (1) Ca(OH)2, H3PO4 and Zn(NO3)2 are added to purified water, and the resulting solution is aged after stirring and dissolving; (2) the aged solution is spray-dried, and the resulting droplets are dispersed in a drying chamber and the particles are collected; (3) the spray-dried hydroxyapatite particles are ball-milled without adding grinding beads; (4) the smooth hydroxyapatite microspheres are sintered at an initial temperature of 50 ℃, a heating rate of 2~4 ℃ / min, a heating time of 110 min, an ending temperature of 400~700 ℃, and a holding time of 30~50 min to obtain porous hydroxyapatite microspheres. Among them, the spray drying parameters are: inlet temperature of 200~220℃, peristaltic pump speed of 13~16 rpm; the ball milling parameters are: rotation speed of 250~350 rpm, and time of 20h~24h.

[0017] In some embodiments, the freeze-drying protectant is one or more of mannitol, trehalose, and polyethylene glycol.

[0018] According to a second aspect of the present invention, a method for preparing the above-mentioned sunscreen agent based on hydroxyapatite microspheres is provided, comprising the following steps: Pretreated water-soluble chitosan was added to water for injection and stirred, then a lyophilization protectant was added to dissolve it and obtain a mobile phase. Hydroxyapatite microspheres were added to the mobile phase as microsphere particles suspended in the mobile phase. After vacuum freeze-drying, the mixture was packaged and sterilized to obtain a long-lasting sunscreen. The mass-volume ratio of water-soluble chitosan to water for injection was 1% to 2%.

[0019] In some implementations, the vacuum freeze-drying procedure is as follows: Section 1: Cold trap temperature -45℃~-50℃, time 12h~16h, vacuum degree 0~30Pa; Section 2: Cold trap temperature -20℃~-25℃, time 6h~8h, vacuum degree 0~30Pa; Section 3: Cold trap temperature -5℃~0℃, time 6h~8h, vacuum degree 0~30Pa; Section 4: Cold trap temperature 15℃~20℃, time 6h~8h, vacuum degree 0~30Pa; Section 5: Cold trap temperature 30℃~35℃, time 6h~8h, vacuum degree 0~30Pa.

[0020] In some implementations, long-lasting sunscreens can be sterilized by irradiation, ethylene oxide, or wet sterilization to achieve a sterile state.

[0021] The sunscreen agent based on hydroxyapatite microspheres provided by this invention can be used through non-invasive and invasive delivery methods. Non-invasive delivery includes atomization, electroporation, ultrasound, and microcurrent, while invasive delivery includes microneedling and roller needle delivery. The long-lasting sunscreen agent is delivered to the stratum spinosum of the epidermis, which is different from the current mainstream physical sunscreens (topical application) and represents a major technological innovation in sunscreen products and technologies.

[0022] Compared with the prior art, the present invention has the following beneficial effects: (1) The sunscreen agent of the present invention can be introduced to the epidermal layer of the skin, unlike the traditional sunscreen agent which is simply applied to maintain the sun protection effect for one or several days. The long-lasting sunscreen agent based on hydroxyapatite microspheres can stay in the epidermal layer of the skin for a long time to absorb and reflect UVB to achieve the sun protection effect until it is completely degraded; moreover, since the hydroxyapatite microspheres have a large specific surface area, their reflective area is large, and they have a better reflective effect on UVB. (2) The sunscreen agent of the present invention has the highest UVB absorption rate and the best sun protection effect because the total Ca and Zn content of the hydroxyapatite microspheres is maintained at 28~35mmol and the Ca:Zn atomic ratio is 7:2~7:4. (3) By using water-soluble chitosan as a sunscreen carrier material, compared with existing carrier materials, the water-soluble chitosan used in this invention has biodegradable stimulating properties and can stimulate collagen production in the same way as the loaded microsphere material, so as to achieve the purpose of dual and gradient stimulation of collagen regeneration. (4) In the sunscreen agent of the present invention, the water-soluble chitosan is formed by the combination of carboxymethyl chitosan and hydroxybutyl chitosan. Carboxymethyl chitosan has antibacterial properties, while hydroxybutyl chitosan has thermosensitive properties. It can not only play an antibacterial role, but also play a supporting role under body temperature conditions and can also be degraded in a gradient. (5) The water-soluble chitosan and hydroxyapatite micrococcus in the sunscreen of the present invention have excellent properties of stimulating collagen regeneration, timely filling properties and gradient degradation properties. Attached Figure Description

[0023] Figure 1 This is a SEM image of the hydroxyapatite microspheres prepared in Example 1 of the present invention.

[0024] Figure 2 EDS image of hydroxyapatite microspheres prepared in Example 1 of this invention.

[0025] Figure 3 The ultraviolet absorption of different groups.

[0026] Figure 4 Use comparison charts for different groups at different times. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to specific embodiments. It is worth noting that the following embodiments are only for better explaining the content of the present invention and do not limit the scope of protection of the present invention. Process steps not disclosed in the embodiments are prior art. Unless otherwise specified, all raw materials are commercially available.

[0028] The water-soluble chitosan used in this embodiment of the invention needs to be pretreated before use. The steps are as follows: (1) All utensils and instruments that come into contact with water-soluble chitosan are rinsed with 2 mol / L NaOH; (2) Water-soluble chitosan is dissolved with 1 mol / L NaOH and filtered using a 0.22 μm ultrafiltration screen; (3) Replace with new 2.5 mol / L NaOH and soak for 30 days, replacing with new 2 mol / L NaOH every 7 days and filtering using a 0.22 μm ultrafiltration screen; (4) Rinse with water for injection, repeating 5 to 10 times until the pH value reaches 6.5 to 7.5; (5) Sterilize.

[0029] Example 1 The sunscreen agent based on hydroxyapatite microspheres in this embodiment comprises, by mass percentage, 13.5% water-soluble chitosan, 42.6% hydroxyapatite microspheres, and 43.9% lyophilization protectant. The water-soluble chitosan is composed of carboxymethyl chitosan and hydroxybutyl chitosan in a mass ratio of 2:1, and the lyophilization protectant used is mannitol.

[0030] The preparation steps are as follows: (1) Preparation of hydroxyapatite microspheres: Ca(OH)2, H3PO4 and Zn(NO3)2 were added to an appropriate amount of purified water. The mass ratio of Ca(OH)2, H3PO4, Zn(NO3)2 and purified water was 1.26:1:1.38:100. The mixture was stirred and dissolved in a stirring tank. The stirred solution was aged for 12 hours. Then, the feed liquid was spray-dried using a centrifugal spray dryer at an inlet temperature of 220℃ and a peristaltic pump speed of 16 rpm. The spray-dried hydroxyapatite particles were then ball-milled at a speed of 350 rpm for 24 hours. The collected hydroxyapatite microspheres were sintered at a sintering temperature of 400℃ to obtain porous hydroxyapatite microspheres. The total content of Ca and Zn was maintained at 32 mmol, the atomic ratio of Ca:Zn was 7:3, and the molar ratio of Ca to P was 1.66. (2) Preparation of long-lasting sunscreen based on hydroxyapatite microspheres: Carboxymethyl chitosan and hydroxybutyl chitosan were added to water for injection in a ratio of 2:1 and stirred evenly. Then, a freeze-drying protectant was added to dissolve and obtain the mobile phase. Finally, hydroxyapatite microspheres were added to the above mobile phase as microsphere particles suspended in the mobile phase. After vacuum freeze-drying, the mixture was packaged and sterilized to obtain a long-lasting sunscreen based on hydroxyapatite microspheres.

[0031] The SEM and EDS images of the hydroxyapatite microspheres prepared in this embodiment are shown below. Figure 1 , Figure 2 As shown in the image, the hydroxyapatite microspheres have a spherical structure with a particle size ranging from 5 μm to 25 μm, and the main elements are Ca, P, Zn, C, and O.

[0032] Example 2 The sunscreen agent based on hydroxyapatite microspheres in this embodiment comprises, by mass percentage, 13.5% water-soluble chitosan, 42.6% hydroxyapatite microspheres, and 43.9% lyophilization protectant. The water-soluble chitosan is composed of carboxymethyl chitosan and hydroxybutyl chitosan in a mass ratio of 2:1, and the lyophilization protectant used is mannitol.

[0033] The preparation method includes the following steps: (1) Preparation of hydroxyapatite microspheres: Ca(OH)2, H3PO4 and Zn(NO3)2 were added to an appropriate amount of purified water. The mass ratio of Ca(OH)2, H3PO4, Zn(NO3)2 and purified water was 1.29:1:0.94:50. The mixture was stirred and dissolved in a stirring tank. The stirred solution was aged for 12 hours. Then, the feed liquid was spray-dried using a centrifugal spray dryer at an inlet temperature of 220 °C and a peristaltic pump speed of 13 rpm. The spray-dried hydroxyapatite particles were then ball-milled at a speed of 250 rpm for 24 hours. The collected hydroxyapatite microspheres were sintered at a sintering temperature of 1200 °C to obtain smooth hydroxyapatite microspheres. The total content of Ca and Zn was maintained at 28 mmol, the atomic ratio of Ca:Zn was 7:2, and the molar ratio of Ca to P was 1.71. (2) Preparation of long-lasting sunscreen based on hydroxyapatite microspheres: Carboxymethyl chitosan and hydroxybutyl chitosan were added to water for injection in a ratio of 2:1 and stirred evenly. Then, a freeze-drying protectant was added to dissolve and obtain the mobile phase. Finally, hydroxyapatite microspheres were added to the above mobile phase as microsphere particles suspended in the mobile phase. After vacuum freeze-drying, the mixture was packaged and sterilized to obtain a long-lasting sunscreen based on hydroxyapatite microspheres.

[0034] Comparative Example 1 The long-lasting sunscreen agent based on hydroxyapatite microspheres in this embodiment includes water-soluble chitosan, hydroxyapatite microspheres and a freeze-dried protectant, wherein, by mass percentage, water-soluble chitosan is 13.5%, hydroxyapatite microspheres are 42.6% and freeze-dried protectant is 43.9%.

[0035] The preparation method includes the following steps (undisclosed conditions and steps are the same as in Example 1): (1) Preparation of hydroxyapatite microspheres: Ca(OH)2 and H3PO4 were added to an appropriate amount of purified water and stirred thoroughly in a mixing tank to dissolve them; the stirred solution was aged and then spray-dried using a centrifugal spray dryer at an inlet temperature of 220℃ and a peristaltic pump speed of 16 rpm. The spray-dried hydroxyapatite particles were then ball-milled at a speed of 350 rpm for 24 h. The collected hydroxyapatite microspheres were then sintered at a sintering temperature of 400℃ to obtain hydroxyapatite microspheres. (2) Preparation of long-lasting sunscreen based on hydroxyapatite microspheres: Carboxymethyl chitosan and hydroxybutyl chitosan were added to water for injection in a ratio of 2:1 and stirred evenly. Then, a freeze-drying protectant was added to dissolve and obtain the mobile phase. Finally, hydroxyapatite microspheres were added to the above mobile phase as microsphere particles suspended in the mobile phase. After vacuum freeze-drying, the mixture was packaged and sterilized to obtain a long-lasting sunscreen based on hydroxyapatite microspheres.

[0036] To verify whether the long-lasting sunscreen based on hydroxyapatite microspheres of the present invention achieves the expected effect, the ultraviolet absorption rate of the long-lasting sunscreen based on hydroxyapatite microspheres prepared in Examples 1-2 and Comparative Example 1 was measured and the sunscreen effect was observed clinically.

[0037] I. Measurement of Ultraviolet Absorption Rate The ultraviolet-visible diffuse reflectance spectra were measured using a UV-Vis recording spectrophotometer (UV-2401, Shimadzu). The spectrophotometer was calibrated using barium sulfate as a reference.

[0038] II. Clinical Observation A clean, dry area without scars or pigmentation was selected from the same human arm; the area was divided into an experimental group and a control group. Each experimental area was given a single 100mJ UVB irradiation, and skin color changes were observed and recorded on days 4 and 7.

[0039] Table 1

[0040] III. Experimental Results 1. Ultraviolet absorption rate Experimental results are as follows Figure 3 As shown in the results of the ultraviolet absorption rate, the sunscreen agent of Example 1 has the strongest absorption rate.

[0041] 2. Clinical observation like Figure 4 As shown in the clinical observation results, both experimental groups 1 and 2 showed fading and indistinct outlines on days 4 and 7, with experimental group 1 showing the most significant fading.

[0042] The above experimental results show that the sunscreen agent based on hydroxyapatite microspheres prepared in this invention has a long-lasting sun protection effect.

[0043] The above descriptions are merely some specific embodiments of the present invention. For those skilled in the art, various modifications and improvements can be made without departing from the inventive concept of the present invention, and all such modifications and improvements fall within the scope of protection of the present invention.

Claims

1. Sunscreen based on hydroxyapatite microspheres, characterized in that, By mass percentage, it comprises 13%–26% water-soluble chitosan, 40%–43% hydroxyapatite microspheres, and 34%–44% lyophilization protectant; the endotoxin content of the water-soluble chitosan does not exceed 0.05 eu / mg, and the total Ca and Zn content of the hydroxyapatite microspheres is maintained at 28–35 mmol, with a Ca:Zn atomic ratio of 7:2–7:

4.

2. The hydroxyapatite microsphere-based sunscreen agent according to claim 1, characterized by, The water-soluble chitosan includes carboxymethyl chitosan and hydroxybutyl chitosan, and the mass ratio of carboxymethyl chitosan to hydroxybutyl chitosan is 3:1 to 1:

3.

3. The hydroxyapatite microsphere-based sunscreen agent according to claim 1 or 2, characterized by, The hydroxyapatite microspheres include one or both of smooth hydroxyapatite microspheres and porous hydroxyapatite microspheres, wherein the porosity of the porous hydroxyapatite microspheres is 20% to 50%.

4. The hydroxyapatite microsphere-based sunscreen agent according to claim 3, characterized by, The hydroxyapatite microspheres have a Ca:P molar ratio of 1.66 to 1.71, a tap density of 0.6 to 1.0 g / cm 3 .

5. The hydroxyapatite microsphere-based sunscreen agent according to claim 3, characterized by, The hydroxyapatite microspheres have particle sizes in two gradient ranges: 5μm~10μm and 10μm~25μm, and the mass ratio of the microspheres in the two particle size gradient ranges is 2:1~1:

1.

6. The sunscreen agent based on hydroxyapatite microspheres according to claim 3, characterized in that, The hydroxyapatite microspheres were prepared by the following method: (1) Ca(OH)2, H3PO4 and Zn(NO3)2 were added to purified water and stirred to dissolve, and the resulting solution was aged; (2) the aged solution was spray-dried, and the resulting droplets were dispersed in the drying chamber and the particles were collected; (3) the spray-dried hydroxyapatite particles were ball-milled; (4) the collected hydroxyapatite microspheres were sintered to obtain hydroxyapatite microspheres.

7. The sunscreen agent based on hydroxyapatite microspheres according to claim 6, characterized in that, The spray drying parameters are: inlet temperature of 200~220℃ and peristaltic pump speed of 13~16 rpm; the ball milling parameters are: rotation speed of 250~350 rpm and time of 20h~24h.

8. The sunscreen agent based on hydroxyapatite microspheres according to claim 1, characterized in that, The freeze-drying protectant is one or more of mannitol, trehalose, and polyethylene glycol.

9. The method for preparing the sunscreen agent based on hydroxyapatite microspheres according to any one of claims 1-8, characterized in that, The process includes the following steps: adding pretreated water-soluble chitosan to water for injection and stirring, then adding a freeze-drying protectant to dissolve and obtain a mobile phase; adding hydroxyapatite microspheres as microsphere particles suspended in the mobile phase, and then packaging and sterilizing after vacuum freeze-drying to obtain a sunscreen agent.

10. The preparation method according to claim 9, characterized in that, The vacuum freeze-drying procedure is as follows: Section 1: Cold trap temperature -45℃~-50℃, time 12h~16h, vacuum degree 0~30Pa; Section 2: Cold trap temperature -20℃~-25℃, time 6h~8h, vacuum degree 0~30Pa; Section 3: Cold trap temperature -5℃~0℃, time 6h~8h, vacuum degree 0~30Pa; Section 4: Cold trap temperature 15℃~20℃, time 6h~8h, vacuum degree 0~30Pa; Section 5: Cold trap temperature 30℃~35℃, time 6h~8h, vacuum degree 0~30Pa.

Images