L-polylactic acid microsphere filler for improving redissolution injection and preparation method of L-polylactic acid microsphere filler

Abstract

The invention provides an injection poly-L-lactic acid microsphere filling agent for improving redissolution. The filling agent is prepared from the following raw materials in parts by weight: 40 to 60 parts of poly-L-lactic acid composite microspheres, 10 to 15 parts of sodium carboxymethyl cellulose, 5 to 8 parts of polysorbate and 10 to 15 parts of mannitol, according to the poly-L-lactic acid composite microspheres, cyclodextrin and poly-L-lactic acid serve as raw materials, a supramolecular structure material with the cyclodextrin as a wheel and the poly-L-lactic acid as an axis can be obtained through the self-assembly effect, and surface group distribution of the poly-L-lactic acid composite microspheres prepared through a solvent evaporation method changes. According to the preparation method, the arrangement mode of sodium carboxymethyl cellulose on the surfaces of the microspheres can be changed, so that the compactness of sodium carboxymethyl cellulose gel is reduced, water molecules can rapidly permeate into the surfaces of the microspheres to be redissolved, the microspheres are prevented from being sticky, particles are prevented from being adhered and settled, and the redissolving property of the filling agent is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of polylactic acid microspheres, and particularly relates to a L-polylactic acid microsphere filler for injection with improved resolubility and a preparation method thereof. Background Art

[0002] Collagen (collagen for short) is an important component of the skin, and it mainly plays a supporting and elastic role. With age or the influence of the external environment (ultraviolet rays), collagen is gradually lost, leading to the formation of wrinkles and folds. Poly-L-lactic acid is non-toxic and has a biological stimulating effect. After injection, it is first wrapped by macrophages, giant cells and other lymphocytes, causing a mild inflammatory reaction within a few months, stimulating the body to produce new collagen and other connective tissue collagen. Poly-L-lactic acid is gradually degraded into lactic acid and finally metabolized into carbon dioxide and water. The new collagen stimulated by poly-L-lactic acid can supplement and replace the lost collagen, strengthen the elastic fiber network of the skin, make the skin firm again, reduce the formation of wrinkles, and delay the aging process of the skin.

[0003] Preparation of poly-L-lactic acid into microspheres, and then compounding with a suspending dispersant, a stabilizer, etc. to prepare a subcutaneous filler for repairing soft tissue volume loss and deeper static wrinkles or folds has attracted widespread attention from researchers. For example, patent CN114712559B discloses an injectable poly-L-lactic acid microsphere that can promote stable regeneration of collagen in vivo and its preparation and application. The method comprises: dissolving poly-L-lactic acid of different viscosities and different molecular chain structures in an organic solvent, and preparing poly-L-lactic acid microspheres by an emulsification method; then stirring the prepared poly-L-lactic acid microspheres with mannitol and sodium carboxymethyl cellulose (CMC) to obtain a mixture; finally, mixing the obtained mixture with water to obtain a mixture and freeze-drying it to obtain a high-yield injectable poly-L-lactic acid microsphere that can promote stable regeneration of collagen in vivo. Patent CN110721338B discloses a method for preparing injectable L-polylactic acid microparticles, comprising the following steps: (1) dispersing L-polylactic acid microspheres into a mixed aqueous solution of carboxymethyl cellulose and mannitol, and freeze-drying; (2) compressing the freeze-dried sample, dissolving the compressed sample in water to form a solution, and freeze-drying again to obtain sheet-like injectable L-polylactic acid microparticles.

[0004] The above is a common method of using L-polylactic acid microspheres as an ingredient for delaying skin aging, combining them with suspending dispersants, stabilizers and other ingredients, and making filler freeze-dried powder products through freeze-drying technology. Among them, carboxymethyl cellulose (or derivatives) and the like have the function of making the L-polylactic acid microspheres evenly dispersed and stably suspended. However, the filler freeze-dried powder obtained after freeze-drying has poor dissolution and dispersibility and a long dissolution and dispersion time. It is speculated that carboxymethyl cellulose (or derivatives) will form a layer of gel network on the surface of the L-polylactic acid microspheres. This layer of network becomes dense after freeze-drying, which can prevent / delay the entry of water molecules, making it difficult for the L-polylactic acid microspheres to be evenly and stably dispersed in the aqueous phase, and the re-dissolution time is long.

[0005] Therefore, it is necessary to further improve the L-polylactic acid microspheres to obtain L-polylactic acid microsphere fillers with uniform microsphere dispersion, stable suspension, good re-dissolution and dispersion effect and short re-dissolution time. Summary of the invention

[0006] In order to solve the technical problems that the freeze-dried powder of L-polylactic acid microsphere filler containing carboxymethyl cellulose (or derivatives) has poor re-dispersion and long re-dissolution time, the present invention provides a L-polylactic acid microsphere filler for injection with improved resolubility and a preparation method thereof. The present invention uses cyclodextrin and L-polylactic acid as raw materials, and can obtain a supramolecular structure material with cyclodextrin as a wheel and L-polylactic acid as an axis through self-assembly. After L-polylactic acid-cyclodextrin precise polyrotaxane and L-polylactic acid are compounded in a specific ratio, the surface group distribution of L-polylactic acid composite microspheres prepared by a solvent volatilization method changes, which can change the arrangement of sodium carboxymethyl cellulose on the surface of the microspheres, thereby reducing the density of the sodium carboxymethyl cellulose gel, facilitating rapid penetration of water molecules into the surface of the microspheres for re-dissolution, and preventing the microspheres from becoming sticky, particles from sticking, and settling.

[0007] In order to achieve the above purpose, the following technical solutions are adopted:

[0008] A L-polylactic acid microsphere filler for injection with improved resolubility comprises the following raw materials in parts by weight: 40-60 parts of L-polylactic acid composite microspheres, 10-15 parts of sodium carboxymethyl cellulose, 5-8 parts of polysorbate, and 10-15 parts of mannitol. The L-polylactic acid composite microspheres are prepared by a method comprising the following steps:

[0009] 1) dissolving L-polylactic acid in solvent A, heating and stirring until completely dissolved to obtain solution A for later use;

[0010] 2) dissolving cyclodextrin in solvent B, heating and stirring until completely dissolved, to obtain solution B, which is set aside;

[0011] 3) Add solution B to solution A, and repeatedly perform heating and cooling reactions under ultrasonic conditions, wherein the heating reaction is performed at 40-80°C for 12-24 hours; the cooling reaction is performed at 20-30°C for 5-8 hours; the heating and cooling reactions are repeated 3-5 times, concentrated, hexane is added until no precipitation is generated, filtered, washed, and vacuum dried to obtain L-polylactic acid-cyclodextrin precise polyrotaxane;

[0012] 4) dissolving the L-polylactic acid-cyclodextrin precise polyrotaxane and the L-polylactic acid complex in an organic solvent to prepare an oil phase, dissolving polyvinyl alcohol in water to prepare an aqueous phase, dropping the oil phase into the aqueous phase, controlling the temperature and stirring to form an emulsion, continuing to stir to completely evaporate the organic solvent, centrifuging, discarding the supernatant, washing with water, and freeze-drying to obtain L-polylactic acid composite microspheres; the mass ratio of the L-polylactic acid-cyclodextrin precise polyrotaxane and the L-polylactic acid complex is 1:10-12.

[0013] Step 1) The solvent A is selected from one or a combination of two or more of ethylene oxide, acetonitrile, chloroform, dichloromethane, 1,1,2-trichloroethane, ethylbenzene, toluene, acetone, and tetrahydrofuran, preferably chloroform. The L-polylactic acid is a linear L-polylactic acid with a weight average molecular weight of 50,000-80,000. The concentration of solution A is 1-1.5 g / mL. The temperature is raised to 40-60°C.

[0014] Step 2) The cyclodextrin is selected from one or a combination of α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin; the solvent B is selected from one or a combination of two or more of water, DMF, and DMSO, preferably DMF. The concentration of solution B is 1-1.5 g / mL. The temperature is raised to 40-60°C.

[0015] Step 3) The temperature-raising reaction and the temperature-lowering reaction process are repeated 3-5 times. The temperature-raising reaction is to rise to 40-80°C and react for 12-24 hours, and the temperature-lowering reaction is to drop to 20-30°C and react for 5-8 hours. The ultrasonic condition is to perform ultrasound at a power of 100-200W. The volume ratio of the solution A to the solution B is 1:5-8. The washing is to wash alternately with DMF and water 1-3 times. The vacuum drying is to dry at 30-60°C and a vacuum degree of 0.01-0.1MPa for 3-8 hours.

[0016] Step 4) The L-polylactic acid is linear L-polylactic acid with a weight average molecular weight of 50,000-80,000. The organic solvent is selected from one or a combination of two or more of acetonitrile, chloroform, and dichloromethane, preferably chloroform. The oil phase concentration is 5-8wt%. The water phase concentration is 0.5-1.5wt%. The viscosity of the polyvinyl alcohol is (25-70)×10 -3Pa·s, alcoholysis degree is 98-99mol%. The volume ratio of the oil phase to the water phase is 1:5-10. The temperature control is to control the temperature at 20-40°C. The stirring speed is 500-800r / min. The water washing is 1-3 times. The freeze-drying conditions are: vacuum degree is 50-80Pa, cold trap temperature is -30°C to -40°C, sublimation temperature is 60-70°C, and time is 8-10h.

[0017] The polysorbate is selected from one or a combination of two or more of Tween T-20, Tween T-40, and Tween T-60, preferably Tween T-40.

[0018] The viscosity of the sodium carboxymethyl cellulose is 800-1500 mPa·s.

[0019] The present invention also provides a method for preparing a L-polylactic acid microsphere filler for injection with improved resolubility, comprising the following steps:

[0020] Sodium carboxymethyl cellulose, polysorbate and mannitol are dissolved in water, and L-polylactic acid composite microspheres are added and mixed evenly to obtain a suspension, which is freeze-dried and irradiated for sterilization to obtain an injectable L-polylactic acid microsphere filler.

[0021] The freeze drying conditions are: vacuum degree of 50-80Pa, cold trap temperature of -30°C to -40°C, sublimation temperature of 60-70°C, and time of 8-10h. The mass ratio of the sodium carboxymethyl cellulose, polysorbate, mannitol, and L-polylactic acid composite microspheres to water is 1:20-30.

[0022] An application of a L-polylactic acid microsphere filler for injection with improved resolubility, comprising adding the filler to physiological saline at a mass ratio of 5-10:100, and mixing the mixture into a uniform suspension.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention uses cyclodextrin and L-polylactic acid as raw materials, and can obtain a supramolecular structure material with cyclodextrin as a wheel and L-polylactic acid as an axis through self-assembly. The surface group distribution of L-polylactic acid composite microspheres prepared by compounding L-polylactic acid-cyclodextrin precise polyrotaxane with L-polylactic acid through a solvent volatilization method changes, changes the arrangement mode of sodium carboxymethyl cellulose on the surface of the microspheres, and then reduces the density of the sodium carboxymethyl cellulose gel, facilitates water molecules to quickly penetrate into the surface of the microspheres for redissolution, and prevents the microspheres from becoming sticky, particles from sticking, and settling. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with specific embodiments, but is not limited to the contents of the specification. Unless otherwise specified, the "parts" described in the embodiments of the present invention are all parts by weight. The reagents used are all commercially available reagents in the art.

[0026] Linear L-polylactic acid with a weight average molecular weight of 76,000 and 50,000 were purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0027] Polyvinyl alcohol PVA124 was purchased from Kuraray, Japan.

[0028] Sodium carboxymethyl cellulose has a viscosity of 1280 mPa·s and was purchased from Shanghai Jichun Industrial Co., Ltd.

[0029] Example 1

[0030] 1) Take L-polylactic acid with a weight average molecular weight of 76,000 and dissolve it in chloroform, raise the temperature to 55°C and stir until it is completely dissolved to obtain a solution A with a concentration of 1.5 g / mL, which is set aside;

[0031] 2) Dissolve α-cyclodextrin in DMF, heat to 60°C and stir until completely dissolved to obtain a solution B with a concentration of 1.5 g / mL, which is set aside;

[0032] 3) Solution B was added to solution A at a volume ratio of 8:1, and the temperature was raised to 80°C for reaction for 12 hours under 100W ultrasonic conditions, and the temperature was lowered to 20°C for reaction for 8 hours. The heating reaction and cooling reaction process were repeated 3 times, and the solution was concentrated by distillation until the volume was reduced to 1 / 4 of the original volume, and hexane was added until there was no precipitation, filtered, and washed alternately with DMF and water for 3 times, and dried at 48°C and a vacuum degree of 0.08MPa for 6 hours to obtain L-polylactic acid-α-cyclodextrin precise polyrotaxane;

[0033] 4) Dissolve L-lactic acid-α-cyclodextrin precise polyrotaxane and L-lactic acid (weight average molecular weight of 76,000) in chloroform at a composite mass ratio of 1:10 to prepare an oil phase with a concentration of 8wt%, dissolve polyvinyl alcohol in water to prepare an aqueous phase with a concentration of 1.5wt%, drop the oil phase into the aqueous phase at a volume ratio of 1:5, control the temperature at 35°C and stir at a speed of 500r / min to form an emulsion, continue stirring to completely evaporate the chloroform, centrifuge, discard the supernatant, wash the precipitate with water 3 times, and freeze-dry under the conditions of a vacuum degree of 80Pa, a cold trap temperature of -40°C, a sublimation temperature of 60°C, and a time of 10h to obtain L-lactic acid composite microspheres;

[0034] 5) Take 10g of sodium carboxymethyl cellulose, 8g of Tween T-20, and 15g of mannitol and dissolve them in 2000g of water, add 60g of L-polylactic acid composite microspheres and mix evenly to obtain a suspension, freeze-dry under the conditions of vacuum degree of 80Pa, cold trap temperature of -40°C, sublimation temperature of 60°C, and time of 10h, and sterilize by irradiation to obtain an injectable L-polylactic acid microsphere filler.

[0035] Example 2

[0036] The rest is the same as Example 1, except that in step 3), solution B is added to solution A at a volume ratio of 5:1.

[0037] Example 3

[0038] The rest is the same as Example 1, except that in step 2), a solution B with a concentration of 1 g / mL is prepared.

[0039] Example 4

[0040] The rest is the same as Example 1, except that, in step 4), L-polylactic acid-α-cyclodextrin precise polyrotaxane and L-polylactic acid with a composite mass ratio of 1:12 are dissolved in chloroform.

[0041] Example 5

[0042] The rest is the same as Example 1, except that in step 5), the amount of L-polylactic acid composite microspheres used is 40 g.

[0043] Example 6

[0044] The rest is the same as Example 1, except that in step 4), the amount of Tween T-20 used is 5 g.

[0045] Example 7

[0046] 1) Take L-polylactic acid with a weight average molecular weight of 50,000 and dissolve it in chloroform, raise the temperature to 55°C and stir until it is completely dissolved to obtain a solution A with a concentration of 1 g / mL, which is set aside;

[0047] 2) Dissolve α-cyclodextrin in DMF, heat to 60°C and stir until completely dissolved to obtain a solution B with a concentration of 1 g / mL, which is set aside;

[0048] 3) Solution B was added to solution A at a volume ratio of 8:1, and the temperature was raised to 80°C for reaction for 12 hours under 200W ultrasonic conditions, and the temperature was lowered to 20°C for reaction for 5 hours. The heating and cooling processes were repeated 3 times, and the solution was concentrated by distillation until the volume was reduced to 1 / 4 of the original volume. Hexane was added until no precipitation occurred, filtered, and washed alternately with DMF and water for 3 times, and dried at 48°C and a vacuum degree of 0.08 MPa for 6 hours to obtain L-polylactic acid-α-cyclodextrin precise polyrotaxane;

[0049] 4) The composite mass ratio of 1:10 of L-polylactic acid-α-cyclodextrin precise polyrotaxane and L-polylactic acid (weight average molecular weight of 50,000) was dissolved in chloroform to prepare an oil phase with a concentration of 8wt%, polyvinyl alcohol was dissolved in water to prepare an aqueous phase with a concentration of 1.5wt%, the oil phase was dropped into the aqueous phase at a volume ratio of 1:10, and stirred at a speed of 500r / min to form an emulsion, and the chloroform was completely evaporated by stirring, centrifuged, the supernatant was discarded, and the precipitate was washed with water for 3 times, and freeze-dried under the conditions of a vacuum degree of 80Pa, a cold trap temperature of -40°C, a sublimation temperature of 60°C, and a time of 10h to obtain L-polylactic acid composite microspheres;

[0050] 5) Take 15g of sodium carboxymethyl cellulose, 5g of Tween T-20, and 10g of mannitol and dissolve them in 1400g of water, add 40g of L-polylactic acid composite microspheres and mix evenly to obtain a suspension, freeze-dry under the conditions of vacuum degree of 80Pa, cold trap temperature of -40°C, sublimation temperature of 60°C, and time for 10h, and irradiate sterilize to obtain an injectable L-polylactic acid microsphere filler.

[0051] Example 8

[0052] The rest is the same as Example 1, except that an equal mass of γ-cyclodextrin is used to replace α-cyclodextrin in step 2).

[0053] Comparative Example 1

[0054] The rest is the same as Example 1, except that in step 3), 300 r / min stirring is used instead of 100 W ultrasound.

[0055] Application Examples

[0056] The fillers of the examples and comparative examples were added with 0.9% physiological saline at a mass ratio of 5:100, and mixed into a uniform suspension using an HVS-6 vertical oscillator from Chongqing Zhongpu Technology Co., Ltd. The suspensions prepared in the above application examples and comparative application examples were subjected to the following performance tests:

[0057] Redissolution time: tested by oscillation method, oscillation parameters are: vertical oscillation mode; oscillation amplitude 40mm; oscillation speed 80r / min. The redissolution time is tested based on the standard that the suspension after mixing is uniform and there are no large particles and lumpy gel visible to the naked eye.

[0058] Particle size analysis: Malvern Zetasizer Nano-ZS90 laser particle size analyzer was used to measure the particle size distribution of microspheres at an operating temperature of 25°C.

[0059] Stability: Place the filled injection in a dark environment at room temperature for 8 hours and 1 day to observe whether there is any sedimentation.

[0060] Table 1 Performance test results

[0061] project Redissolution time min Average particle size μm 8h stability 1d stability Example 1 16 28 No settlement No settlement Example 2 18 30 No settlement No settlement Example 3 17 29 No settlement No settlement Example 4 18 33 No settlement No settlement Example 5 14 35 No settlement No settlement Example 6 15 34 No settlement No settlement Example 7 17 31 No settlement No settlement Example 8 17 29 No settlement There is sedimentation Comparative Example 1 22 40 There is sedimentation There is sedimentation

[0062] It can be seen from Table 1 that the L-polylactic acid microsphere filler for injection prepared by the present invention can be evenly dispersed and stably suspended after re-dissolution without sedimentation and particle adhesion.

[0063] The above detailed description is a specific description of one feasible embodiment of the present invention. The embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification that does not deviate from the present invention should be included in the scope of the technical solution of the present invention.

Claims

1. A poly(L-lactic acid) microsphere filler for injection with improved resolubility, characterized in that: The invention comprises the following raw materials in parts by weight: 40-60 parts of L-polylactic acid composite microspheres, 10-15 parts of sodium carboxymethyl cellulose, 5-8 parts of polysorbate, and 10-15 parts of mannitol. The L-polylactic acid composite microspheres are prepared by a method comprising the following steps: 1) dissolving L-polylactic acid in solvent A, heating and stirring until completely dissolved to obtain solution A for later use; 2) dissolving cyclodextrin in solvent B, heating and stirring until completely dissolved to obtain solution B for later use; 3) Add solution B to solution A, and repeatedly perform heating and cooling reactions under ultrasonic conditions, wherein the heating reaction is performed at 40-80°C for 12-24 hours; the cooling reaction is performed at 20-30°C for 5-8 hours; the heating and cooling reactions are repeated 3-5 times, concentrated, hexane is added until no precipitation is generated, filtered, washed, and vacuum dried to obtain L-polylactic acid-cyclodextrin precise polyrotaxane; 4) dissolving the L-polylactic acid-cyclodextrin precise polyrotaxane and the L-polylactic acid complex in an organic solvent to prepare an oil phase, dissolving polyvinyl alcohol in water to prepare an aqueous phase, dropping the oil phase into the aqueous phase, controlling the temperature and stirring to form an emulsion, continuing to stir to completely evaporate the organic solvent, centrifuging, discarding the supernatant, washing with water, and freeze-drying to obtain L-polylactic acid composite microspheres; the mass ratio of the L-polylactic acid-cyclodextrin precise polyrotaxane and the L-polylactic acid complex is 1:10-12.

2. The poly(L-lactic acid) microsphere filler for injection with improved resolubility according to claim 1, characterized in that: Step 1) the L-polylactic acid is linear L-polylactic acid with a weight average molecular weight of 50,000-80,000; the concentration of solution A is 1-1.5 g / mL; and the temperature is raised to 40-60°C.

3. The poly(L-lactic acid) microsphere filler for injection with improved resolubility according to claim 1, characterized in that: Step 2) the cyclodextrin is selected from one or a combination of α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin; the concentration of solution B is 1-1.5 g / mL; and the temperature is raised to 40-60°C.

4. The poly(L-lactic acid) microsphere filler for injection with improved resolubility according to claim 1, characterized in that: Step 3) The volume ratio of solution A to solution B is 1:5-8.

5. The poly(L-lactic acid) microsphere filler for injection with improved resolubility according to claim 1, characterized in that: The ultrasonic condition of step 3) is to perform ultrasonication at a power of 100-200W.

6. The poly(L-lactic acid) microsphere filler for injection with improved resolubility according to claim 1, characterized in that: Step 4) The L-polylactic acid is linear L-polylactic acid with a weight average molecular weight of 50,000-80,000.

7. The poly(L-lactic acid) microsphere filler for injection with improved resolubility according to claim 1, characterized in that: Step 4) The oil phase concentration is 5-8wt%; the water phase concentration is 0.5-1.5wt%; the volume ratio of the oil phase to the water phase is 1:5-10.

8. The poly(L-lactic acid) microsphere filler for injection with improved resolubility according to claim 1, characterized in that: The polysorbate is selected from one or a combination of two or more of Tween T-20, Tween T-40, and Tween T-60, preferably Tween T-40; the viscosity of the sodium carboxymethyl cellulose is 800-1500 mPa·s.

9. The method for preparing the injection-use poly(L-lactic acid) microsphere filler with improved resolubility according to any one of claims 1 to 8, characterized in that: The steps include: Sodium carboxymethyl cellulose, polysorbate and mannitol are dissolved in water, and L-polylactic acid composite microspheres are added and mixed evenly to obtain a suspension, which is freeze-dried and irradiated for sterilization to obtain an injectable L-polylactic acid microsphere filler.

10. The method for preparing the injection-use poly(L-lactic acid) microsphere filler with improved resolubility according to claim 9, characterized in that: The mass ratio of the sodium carboxymethyl cellulose, polysorbate, mannitol and L-polylactic acid composite microspheres to water is 1:20-30.