Porous bio-based polymer microsphere as well as preparation method and application thereof

Abstract

The invention provides a porous bio-based polymer microsphere as well as a preparation method and application thereof. The porous bio-based polymer microsphere provided by the invention comprises a mixture of a bio-based high-molecular polymer P1 and a bio-based block copolymer P2, wherein the bio-based block copolymer P2 is a bio-based block copolymer of which the end-capped group at one end is a hydrophilic group and the end-capped group at the other end is a hydrophobic group. The porous microspheres are prepared by adopting a method of combining condensation phase separation, solvent replacement and solvent volatilization, the obtained microspheres are uniform and stable, the pelletizing rate of the microspheres is nearly high, the yield is high, and subsequent screening is not needed; the process is simple, and the difficulty in operation and control of the process caused by introduction of multiple water phases / oil phases is reduced.

Description

Technical Field

[0001] The present invention belongs to the field of polymer technology, and in particular relates to porous bio-based polymer microspheres and a preparation method and application thereof. Background Art

[0002] Porous polymer microspheres have an internal porous structure and a high porosity. Porous microspheres prepared with biodegradable materials have broad application prospects in chemical environmental protection fields such as soil protection, water treatment, and oil-water separation, as well as in biomedical fields such as toxin adsorption in the body, in vitro cell culture, tissue engineering, and drug screening.

[0003] Currently, many methods are used to prepare porous microspheres, such as foaming, emulsion, spray drying, phase separation, freeze drying, and electrospinning. For example, the freeze drying method disclosed in Chinese patent CN117567788A cannot produce porous microspheres with stable and controllable pore sizes. The phase separation method proposed in patents CN114621491A and CN113321840B for preparing porous microspheres, while simple in process, suffers from poor spherical shape and a low yield of qualified microspheres. In a paper published by Wang Shige et al. entitled "Preparation of Multifunctional Polyvinyl Alcohol Microspheres by Electrospinning, Their Properties and Applications," porous microspheres were prepared using electrospinning technology. However, the electrospinning process is relatively complex, with harsh process conditions, low microsphere yield, and is not suitable for preparing porous microspheres. Currently, porous polyester microspheres are primarily prepared using a water-in-oil-in-water double emulsion coupled with solvent evaporation, as disclosed in Chinese patents CN115350325A, CN117430861A, and CN115417940A. However, the preparation process for preparing polyester porous microspheres using double emulsions is complex, time-consuming, and requires additional processing to prepare the porogen. This limits the large-scale production of microspheres. Furthermore, the use of surfactants or inorganic salts such as ammonium and sodium salts as porogens often makes it difficult to achieve stable control of the pore size and porosity of the porous microspheres. Furthermore, the resulting microspheres are poorly spherical and uneven in size. Furthermore, the commonly used preparation methods often result in chemical reagents such as porogens or surfactants remaining within the microspheres, impacting their subsequent applications. Summary of the Invention

[0004] In response to the problems existing in the prior art, the present invention provides porous bio-based polymer microspheres, their preparation method, and applications. The present invention utilizes bio-based high molecular weight polymers and block copolymers to prepare porous bio-based polymer microspheres through three process steps: condensation phase separation, solvent displacement, and solvent volatilization. The present invention first introduces two organic solvents during the preparation process, achieving phase separation through emulsification and condensation to obtain a microsphere material. Subsequently, ultrapure water is used to displace the condensed organic solvent at a certain temperature, and the remaining organic solvent is then volatilized at a certain temperature. The resulting material is a porous polymer microsphere material.

[0005] One of the objectives of the present invention is to provide porous bio-based polymer microspheres, comprising a mixture of a bio-based high molecular weight polymer P1 and a bio-based block copolymer P2, wherein the bio-based block copolymer P2 is a bio-based block copolymer having a hydrophilic end-capping group at one end and a hydrophobic end-capping group at the other end.

[0006] According to the present invention, in the porous bio-based polymer microspheres:

[0007] The bio-based polymer P1 is at least one selected from polylactic acid, polyglycolic acid, polylactic acid-glycolic acid copolymer, polycaprolactone, polydioxanone, and polyamino acid-derived carbonate;

[0008] The weight average molecular weight of the bio-based high molecular weight polymer P1 is 1,000 to 600,000, preferably 4,000 to 100,000;

[0009] The bio-based block copolymer P2 is selected from at least one of polylactic acid / polyethylene glycol block copolymers or derivatives thereof, polylactic acid-co-glycolic acid / polyethylene glycol block copolymers or derivatives thereof, polylactic acid / polyamino acid block copolymers or derivatives thereof, and polylactic acid-co-glycolic acid / polyamino acid block copolymers or derivatives thereof;

[0010] The number average molecular weight of the bio-based block copolymer P2 is 1,000 to 100,000, preferably 5,000 to 50,000;

[0011] The mass ratio of the bio-based block copolymer P2 to the bio-based high molecular polymer P1 is (0.01-2):1, preferably (0.05-1.5):1.

[0012] A second object of the present invention is to provide a method for preparing the above-mentioned porous bio-based polymer microspheres, comprising the steps of subjecting a dual organic solvent system containing the bio-based high molecular weight polymer P1 and the bio-based block copolymer P2 to phase separation, replacing the solvent with ultrapure water, and volatilizing the solvent.

[0013] According to the present invention, the method for preparing the porous bio-based polymer microspheres specifically comprises the following steps:

[0014] (1) A bio-based polymer P1, an organic solvent A, and an organic solvent B are stirred to form a mixed solution (I);

[0015] (2) adding the bio-based block copolymer P2 to the mixed solution (I) obtained in step (1) and fully dissolving it to obtain a mixed solution (II);

[0016] (3) adding the mixed solution (II) obtained in step (2) to solvent C, homogenizing at high speed to obtain an emulsion, and storing at low temperature;

[0017] (4) adding pre-cooled ultra-light water to the emulsion stored at low temperature in step (3) to perform a replacement operation to obtain a mixed solution (III);

[0018] (5) The mixed solution (III) is post-treated to obtain the porous bio-based polymer microspheres.

[0019] According to the present invention, in step (1) of the method for preparing porous bio-based polymer microspheres:

[0020] The organic solvent A is selected from at least one of halogenated alkanes, preferably at least one of dichloromethane and chloroform;

[0021] The organic solvent B is selected from at least one of oxygen-containing polar organic solvents, preferably at least one of 1,4-dioxane, hexafluoroisopropanol, acetone, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide, and more preferably at least one of 1,4-dioxane, hexafluoroisopropanol, and acetone;

[0022] Based on 100 parts by weight of the bio-based polymer P1, the organic solvent A is 100 to 3000 parts, and the organic solvent B is 1 to 1000 parts; preferably, based on 100 parts by weight of the bio-based polymer P1, the organic solvent A is 100 to 2000 parts, and the organic solvent B is 5 to 750 parts;

[0023] Natural polymers and / or bioactive ingredients are optionally added to the mixed solution (I). Preferably, the natural polymers and / or bioactive ingredients are selected from at least one of polypeptide proteins, water-insoluble drugs, bioactive factors, and natural polymers. The amount of the natural polymers and / or bioactive ingredients added is 0-1 wt%, preferably 0-0.2 wt%, of the bio-based polymer P1.

[0024] Natural polymers and / or bioactive ingredients are optionally added to the mixed solution (I) so that the obtained polymer microspheres have properties such as biocompatibility, bioactivity, adsorption, and drug release.

[0025] The polypeptide protein can be selected from at least one of bovine serum albumin, lipoprotein, ovalbumin, myosin, globulin, transferrin, keratin, casein, mucin, hemoglobin, bone morphogenetic protein, pepsin, lysozyme, thromboplastin, interleukin, bivalirudin, interferon, reteplase, sagistin, asparaginase, anakinra, and collagenase;

[0026] The water-insoluble drug can be selected from paclitaxel, docetaxel, larotaxel, cabazitaxel, doxorubicin, vincristine and derivatives, cephalosporin and derivatives, camptothecin, etoposide, curcumin, retinoic acid, fluorouracil, methotrexate, teniposide, etoposide, daunorubicin, rapamycin, aclarubicin, sorafenib, methylprednisone, minocycline, dexamethasone, cisplatin, atorvastatin, simvastatin, lovastatin, comprenoside, lomustine, amiodarone, carbamazepine, carvedilol, chlorpromazine, At least one of cisapride, dapsone, mitomycin, azithromycin, neomycin, actinomycin, amphotericin B, griseofulvin, celecoxib, raloxifene, flurbiprofen, indomethacin, ibuprofen, tamoxifen, diclofenac, naproxen, piroxicam, raltegravir, efavirenz, nelfinavir, atazanavir, ritonavir, sirolimus, spironolactone, tacrolimus, talinolol, magnolol, terfenadine, estradiol, vitamin A, vitamin D, vitamin E, vitamin K, cyclosporine, or insulin;

[0027] The bioactive factor may be selected from at least one of coagulation factors and growth factors;

[0028] The natural polymer may be selected from at least one of hydrophobic chitosan, hydroxypropyl methylcellulose acetate succinate, and ethyl cellulose.

[0029] According to the present invention, in step (1) of the method for preparing porous bio-based polymer microspheres:

[0030] The preparation of the mixed solution (I) specifically includes:

[0031] Method (a): (a-1) dissolving the bio-based high molecular polymer P1 in an organic solvent A and stirring uniformly, preferably, the stirring temperature in step (a-1) is 10-20°C; (a-2) continuously adding an organic solvent B and stirring and mixing uniformly to obtain a mixed solution (I); preferably, the stirring temperature in step (a-2) is 20-30°C; or,

[0032] Method (b): dissolving the bio-based high molecular polymer P1 in a mixed solvent of organic solvent A and organic solvent B and stirring uniformly to obtain a mixed solution (I). Preferably, the stirring temperature in method (b) is 10-30°C.

[0033] According to the present invention, in step (2) of the method for preparing porous bio-based polymer microspheres:

[0034] The mass ratio of the bio-based block copolymer P2 to the bio-based high molecular polymer P1 is (0.01-2):1, preferably (0.05-1.5):1;

[0035] The dissolution temperature of the bio-based block copolymer P2 added to the mixed solution (I) is not particularly limited. For example, the dissolution temperature is 10 to 35°C.

[0036] According to the present invention, in step (3) of the method for preparing porous bio-based polymer microspheres:

[0037] The solvent C is selected from water or a polymer solution. The polymer solution is preferably an aqueous solution of at least one of polyethylene glycol, polyvinyl alcohol, water-soluble cellulose, water-soluble chitosan, and gelatin. More preferably, the mass percentage concentration of the polymer in the polymer solution is 0.1% to 5%, and further preferably 0.5% to 1%.

[0038] The mass ratio of the mixed solution (II) to the solvent C is 1:(1-10), preferably 1:(3-6);

[0039] The stirring speed of the high-speed homogenization is 800-2000ppm, preferably 1000-1500ppm;

[0040] The cryopreservation temperature is -70 to 0°C, preferably -15 to 0°C;

[0041] The low-temperature storage time is 0.5 to 5 hours, preferably 1 to 3 hours.

[0042] According to the present invention, in step (4) of the method for preparing porous bio-based polymer microspheres:

[0043] The mass ratio of the emulsion to ultra-light water is (1-20):1, preferably (1-5):1;

[0044] The temperature of the ultra-light water is 2-4°C;

[0045] The operation process of replacing the solvent with ultra-light water is as follows: ultra-light water is added to the emulsion stored at low temperature, soaked for 3 to 6 hours, and then centrifuged; the lower layer of material is removed and ultra-light water is added to repeat the soaking and centrifugation operations until no oily matter is left after soaking with ultra-light water, thereby obtaining a mixed solution (III).

[0046] According to the present invention, in step (5) of the method for preparing porous bio-based polymer microspheres:

[0047] The post-treatment includes the steps of heating, stirring, filtering, washing and drying; preferably,

[0048] The heating and stirring conditions are 55-65°C and stirring for 2-6 hours;

[0049] The cleaning solution used for the cleaning is selected from at least one of hydrochloride buffer, borate buffer, nitrate buffer, sulfate buffer, phosphate buffer, citrate buffer, carbonate buffer, acetate buffer, barbiturate buffer, and Tris buffer; the number of cleaning times is not less than 3 times;

[0050] The drying is freeze drying or vacuum drying. Specifically, the freeze drying can adopt the freeze drying equipment and process conditions commonly used in the prior art, and the vacuum drying can also adopt the vacuum drying conditions commonly used in the prior art, for example, the freeze drying conditions are -80 to -30°C and freeze drying for 12 to 48 hours, and the vacuum drying conditions are 30 to 50°C and vacuum drying for 6 to 24 hours.

[0051] The third object of the present invention is to provide a porous bio-based polymer microsphere according to the first object of the present invention or the porous bio-based polymer microsphere obtained by the preparation method according to the second object of the present invention, wherein the porous bio-based polymer microsphere has a particle size of 5 to 500 μm, a pore size of 0.01 to 50 μm, and a specific surface area of ​​90 to 150 m 2 / g, and the porosity is 75-99%.

[0052] A fourth objective of the present invention is to provide the aforementioned porous bio-based polymer microspheres for use as adsorbents, carriers, and scaffolds. Specifically, the porous bio-based polymer microspheres provided by the present invention can be used not only as adsorbents but also in biomedical applications such as tissue engineering scaffolds, cell culture carriers, and tissue repair fillers; in pharmaceutical applications such as drug carriers, sustained-release drugs, and adjuvant development; and in chemical and environmental protection applications such as water treatment, soil remediation, and oil-water separation.

[0053] The dual solvent system used in the present invention comprises a halogenated alkane organic solvent A and an oxygen-containing polar organic solvent B. The emulsion is stored at low temperature to achieve phase separation, the halogenated alkane solvent is removed, and then ultra-light water is added to replace the oxygen-containing organic solvent, and the residual organic solvent is fully volatilized and dried.

[0054] The present invention can obtain porous microspheres with different pore structures by regulating the ratio of organic solvent A and organic solvent B. The prepared porous polymer microspheres have high sphericity and high yield. The particle size of the microspheres ranges from 5 to 500 μm, and the pore size can be controlled to be 0.01 to 50 μm, which meets practical application requirements.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] (1) In the process of preparing the biodegradable polymer porous microspheres of the present invention, no surfactant or inorganic salt is used as a foaming agent. The obtained porous microspheres have no chemical reagent residue and do not need to be further cleaned, thus saving process steps and process costs.

[0057] (2) The present invention introduces dual organic solvents into the preparation system, and porous microsphere materials with different pore sizes and porosities can be obtained by regulating the ratio of the two organic solvents, which has great application potential in the fields of biomedicine, chemical industry and environmental protection.

[0058] (3) The present invention adopts a method combining condensed phase separation, solvent replacement and solvent volatilization to prepare porous microspheres. The three process flows are indispensable, and the obtained microspheres are uniform and stable. Compared with the single phase separation or solvent replacement method, the microsphere formation rate is close to high, the yield is high, and no subsequent screening is required; compared with the double emulsion method, the present invention uses a single emulsion method, the process is relatively simple, and the difficulty of process operation and control caused by the introduction of multiple water phases / oil phases is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figures 1 to 10 These are electron microscope images of porous bio-based polymer microspheres prepared in Examples 1 to 7 and Comparative Examples 1 to 3, respectively.

[0060] Figures 11-15 The water contact angle images of porous bio-based polymer microspheres were obtained for Examples 1, 6, 7 and Comparative Examples 1 and 3, respectively. DETAILED DESCRIPTION

[0061] The present invention will be described in detail below with reference to specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and are not to be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art to the present invention based on the contents of the present invention still fall within the scope of protection of the present invention.

[0062] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, for example, they can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0063] Example 1

[0064] (1) Dissolve 5 g of polylactic acid (PLA) with a weight average molecular weight of 100,000 in 95 g of dichloromethane, and stir at 10° C. and 200 rpm until the mixture is uniformly dissolved and free of bubbles and solids, thereby obtaining a dichloromethane solution of PLA.

[0065] (2) Add 10 g of 1,4-dioxane to the solution at 24°C and stir at 200 rpm to obtain a mixed solution;

[0066] (3) Add 0.5 g of mPEG-b-PLGA (Sigma-Aldrich, PEG Mn 5000, PLGAMn 7000) to the mixture and stir at 150 rpm for 3 h to mix thoroughly.

[0067] (4) The mixture was added to 400 mL of deionized water at 24°C and homogenized at 1000 rpm for 5 min to obtain an emulsion, which was then stored at -5°C for 2 h.

[0068] (5) The low-temperature treated emulsion was transferred to a low-temperature environment of 4°C, and 150 mL of 4°C ultralight water was added to start solvent replacement. The material was centrifuged every 3 h using a 4°C low-temperature high-speed centrifuge. Subsequently, 4°C ultralight water was added until no oily substance was left after immersion in ultralight water, indicating that the solvent replacement was complete.

[0069] (6) The mixture of the material and ultralight water was heated to 60°C in a water bath and stirred at 150 rpm for 2 h. The material in the mixture was filtered and washed three times with phosphate buffer solution (pH = 7.4). Finally, the mixture was vacuum dried at 40°C for 12 h to obtain a porous polymer microsphere material.

[0070] Example 2

[0071] (1) 8 g of poly(lactic acid-co-glycolic acid) with a weight average molecular weight of 60,000 was dissolved in 92 g of chloroform, and the mixture was stirred at 10° C. and 200 rpm until no bubbles or solids were left, to obtain a solution;

[0072] (2) Add 20 g of 1,4-dioxane to the solution at 20°C and stir at 200 rpm to obtain a mixed solution;

[0073] (3) Add 0.5 g of mPEG-b-PLGA (Sigma-Aldrich, PEG Mn 5000, PLGAMn 7000) to the mixture and stir at 150 rpm for 3 h to mix thoroughly.

[0074] (4) The mixture was added to 600 mL of deionized water at 24°C and homogenized at 1000 rpm for 5 min to obtain an emulsion, which was then stored at -5°C for 2 h.

[0075] (5) The low-temperature treated emulsion was transferred to a low-temperature environment of 4°C, and 180 mL of 4°C ultralight water was added to start solvent replacement. The material was centrifuged every 3 h using a 4°C low-temperature high-speed centrifuge. Subsequently, 4°C ultralight water was added until no oily substance was left after immersion in ultralight water, indicating that the solvent replacement was complete.

[0076] (6) The mixture of the material and ultralight water was heated to 60°C in a water bath and stirred at 150 rpm for 2 h. The material in the mixture was filtered and washed three times with a phosphate buffer solution (pH = 7.4). Finally, the mixture was frozen in a -40°C refrigerator for 6 h and dried in a -80°C freezer for 24 h to obtain a porous polymer microsphere material.

[0077] Example 3

[0078] (1) 8 g of polylactic acid (PLA) with a weight average molecular weight of 60,000 was dissolved in 92 g of dichloromethane, and the mixture was stirred at 10° C. and 200 rpm until no bubbles or solids were left, thereby obtaining a dichloromethane solution of PLA.

[0079] (2) Add 10 g of 1,4-dioxane to the solution at 24°C and stir at 200 rpm to obtain a mixed solution;

[0080] (3) Add 0.5 g of mPEG-b-PLGA (Sigma-Aldrich, PEG Mn 5000, PLGAMn 7000) to the mixture and stir at 150 rpm for 3 h to mix thoroughly.

[0081] (4) The mixture was added to 400 mL of deionized water at 24°C and homogenized at 1000 rpm for 5 min to obtain an emulsion, which was then stored at -5°C for 2 h.

[0082] (5) The low-temperature treated emulsion was transferred to a low-temperature environment of 4°C, and 150 mL of 4°C ultralight water was added to start solvent replacement. The material was centrifuged every 3 h using a 4°C low-temperature high-speed centrifuge. Subsequently, 4°C ultralight water was added until no oily substance was left after immersion in ultralight water, indicating that the solvent replacement was complete.

[0083] (6) The mixture of the material and ultralight water was heated to 60°C in a water bath and stirred at 150 rpm for 2 h. The material in the mixture was filtered and washed three times with phosphate buffer solution (pH = 7.4). Finally, it was vacuum-dried at 40°C for 12 h to obtain a porous polymer microsphere material.

[0084] Example 4

[0085] (1) Dissolve 5 g of polylactic acid (PLA) with a weight average molecular weight of 100,000 in 95 g of dichloromethane, and stir at 10° C. and 200 rpm until the mixture is uniformly dissolved and free of bubbles and solids, thereby obtaining a dichloromethane solution of PLA.

[0086] (2) At 24°C, add 10 g of 1,4-dioxane to the solution and stir at 200 rpm to mix evenly; then add 0.5 g of ethyl cellulose and stir at 200 rpm to obtain a mixed solution;

[0087] (3) Add 0.5 g of mPEG-b-PLGA (Sigma-Aldrich, PEG Mn 5000, PLGAMn 7000) to the mixture and stir at 150 rpm for 3 h to mix thoroughly.

[0088] (4) The mixture was added to 400 mL of deionized water at 24°C and homogenized at 1000 rpm for 5 min to obtain an emulsion, which was then stored at -5°C for 2 h.

[0089] (5) The low-temperature treated emulsion was transferred to a low-temperature environment of 4°C, and 150 mL of 4°C ultralight water was added to start solvent replacement. The material was centrifuged every 3 h using a 4°C low-temperature high-speed centrifuge. Subsequently, 4°C ultralight water was added until no oily substance was left after immersion in ultralight water, indicating that the solvent replacement was complete.

[0090] (6) The mixture of the material and ultralight water was heated to 60°C in a water bath and stirred at 150 rpm for 2 h. The material in the mixture was filtered and washed three times with phosphate buffer solution (pH = 7.4). Finally, the mixture was vacuum dried at 40°C for 12 h to obtain a porous polymer microsphere material.

[0091] Example 5

[0092] (1) 5 g of polylactic acid with a weight average molecular weight of 100,000 was dissolved in a mixed solution of 95 g of dichloromethane and 10 g of 1,4-dioxane, and the mixture was stirred at 10° C. and 200 rpm until no bubbles or solids were left, thereby obtaining a polylactic acid solution;

[0093] (2) Add 0.5 g of mPEG-b-PLGA (Sigma-Aldrich, PEG Mn 5000, PLGAMn 7000) to the mixture and stir at 150 rpm for 3 h to mix thoroughly.

[0094] (3) The mixture was added to 400 mL of deionized water at 24°C and homogenized at 1000 rpm for 5 min to obtain an emulsion, which was then stored at -5°C for 2 h.

[0095] (4) The low-temperature treated emulsion was transferred to a low-temperature environment of 4°C, and 150 mL of 4°C ultralight water was added to start solvent replacement. The material was centrifuged every 3 h using a 4°C low-temperature high-speed centrifuge. Subsequently, 4°C ultralight water was added until no oily substance was left after soaking in ultralight water, indicating that the solvent replacement was complete.

[0096] (5) The mixture of the material and ultralight water was heated to 60°C in a water bath and stirred at 150 rpm for 2 h. The material in the mixture was filtered and washed three times with phosphate buffer solution (pH = 7.4). Finally, the mixture was vacuum dried at 40°C for 12 h to obtain a porous polymer microsphere material.

[0097] Example 6

[0098] The steps were the same as those in Example 1, except that the amount of block copolymer PEG-b-PLGA added was 1 g.

[0099] Example 7

[0100] The steps were the same as those in Example 1, except that the amount of block copolymer PEG-b-PLGA added was 1.5 g.

[0101] Example 8

[0102] (1) Dissolve 5 g of polylactic acid (PLA) with a weight average molecular weight of 100,000 in 95 g of dichloromethane, and stir at 10° C. and 200 rpm until the mixture is uniformly dissolved and free of bubbles and solids, thereby obtaining a dichloromethane solution of PLA.

[0103] (2) Add 10 g of 1,4-dioxane to the solution at 24°C and stir at 200 rpm to obtain a mixed solution;

[0104] (3) Add 0.5 g of mPEG-b-PLGA (Sigma-Aldrich, PEG Mn 5000, PLGAMn 7000) to the mixture and stir at 150 rpm for 3 h to mix thoroughly.

[0105] (4) The mixture was added to 400 mL of a 1 wt% polyvinyl alcohol aqueous solution at 24°C and homogenized at 1000 rpm for 5 min to obtain an emulsion, which was then stored at -5°C for 2 h.

[0106] (5) The low-temperature treated emulsion was transferred to a low-temperature environment of 4°C, and 150 mL of 4°C ultralight water was added to start solvent replacement. The material was centrifuged every 3 h using a 4°C low-temperature high-speed centrifuge. Subsequently, 4°C ultralight water was added until no oily substance was left after immersion in ultralight water, indicating that the solvent replacement was complete.

[0107] (6) The mixture of the material and ultralight water was heated to 60°C in a water bath and stirred at 150 rpm for 2 h. The material in the mixture was filtered and washed three times with phosphate buffer solution (pH = 7.4). Finally, the mixture was vacuum dried at 40°C for 12 h to obtain a porous polymer microsphere material.

[0108] Comparative Example 1 (Condensed Phase Separation and Solvent Replacement Method Not Adopted)

[0109] (1) Dissolve 5 g of polylactic acid (PLA) with a weight average molecular weight of 100,000 in 95 g of dichloromethane, and stir at 10° C. and 200 rpm until the mixture is uniformly dissolved and free of bubbles and solids, thereby obtaining a dichloromethane solution of PLA.

[0110] (2) The mixture was added to 400 mL of deionized water at 24°C and homogenized at 1000 rpm for 5 min to obtain an emulsion;

[0111] (3) The emulsion was heated to 60°C in a water bath and stirred at 150 rpm for 2 h. The material in the mixed solution was filtered, washed three times with phosphate buffer (pH = 7.4), and vacuum dried at 40°C for 12 h to obtain a solid material.

[0112] Comparative Example 2 (without condensation phase separation)

[0113] (1) Dissolve 5 g of polylactic acid (PLA) with a weight average molecular weight of 100,000 in 95 g of dichloromethane, and stir at 10° C. and 200 rpm until the mixture is uniformly dissolved and free of bubbles and solids, thereby obtaining a dichloromethane solution of PLA.

[0114] (2) Add 10 g of 1,4-dioxane to the solution at 24°C and stir at 200 rpm to obtain a mixed solution;

[0115] (3) Add 0.5 g of mPEG-b-PLGA (Sigma-Aldrich, PEG Mn 5000, PLGAMn 7000) to the mixture and stir at 150 rpm for 3 h to mix evenly;

[0116] (4) The mixture was added to 400 mL of deionized water at 24°C and homogenized at 1000 rpm for 5 min to obtain an emulsion;

[0117] (5) The emulsion was transferred to a low-temperature environment at 4°C, and 150 mL of 4°C ultralight water was added to start solvent replacement. The material was centrifuged every 3 h in a 4°C low-temperature high-speed centrifuge. Subsequently, 4°C ultralight water was added until no oily substance was left after immersion in ultralight water, indicating that the solvent replacement was complete.

[0118] (6) The mixture of the material and ultralight water was heated to 60°C in a water bath and stirred at 150 rpm for 2 h. The material in the mixture was filtered and washed three times with phosphate buffer solution (pH = 7.4). Finally, it was vacuum-dried at 40°C for 12 h to obtain a solid material.

[0119] Comparative Example 3 (no block copolymer added)

[0120] (1) 5 g of polylactic acid with a weight average molecular weight of 100,000 was dissolved in a mixed solution of 95 g of dichloromethane and 10 g of 1,4-dioxane, and the mixture was stirred at 10° C. and 200 rpm until no bubbles or solids were left, thereby obtaining a polylactic acid solution;

[0121] (2) The mixture was added to 400 mL of deionized water at 24°C and homogenized at 1000 rpm for 5 min to obtain an emulsion, which was then stored at -5°C for 2 h.

[0122] (3) The low-temperature treated emulsion was transferred to a low-temperature environment of 4°C, and 150 mL of 4°C ultralight water was added to start solvent replacement. The material was centrifuged every 3 h using a 4°C low-temperature high-speed centrifuge. Subsequently, 4°C ultralight water was added until no oily substance was left after immersion in ultralight water, indicating that the solvent replacement was complete.

[0123] (4) The mixture of the material and ultralight water was heated to 60°C in a water bath and stirred at 150 rpm for 2 h. The material in the mixture was filtered and washed three times with phosphate buffer solution (pH = 7.4). Finally, the mixture was vacuum dried at 40°C for 12 h to obtain a porous polymer microsphere material.

[0124] Test Example 1

[0125] The surface micromorphology of the materials obtained in Examples 1 to 7 and Comparative Examples 1 to 3 was observed using a scanning electron microscope. Figures 1 to 10 shown.

[0126] Compared with Example 2, the pore structures of the porous microspheres are somewhat different due to the different types of polymers.

[0127] Compared with Example 3, Example 1 shows that the pore structure of the porous microsphere surface becomes more compact with the increase of polymer content;

[0128] Compared with Example 4, with the introduction of the functional polymer (ethyl cellulose), the surface pore structure of the material is more compact and the surface microstructure is changed;

[0129] The microscopic morphologies of the porous microspheres in Example 1 and Example 5 are basically consistent;

[0130] Compared with Examples 6-7, Example 1 shows that as the content of block polymer inside the microspheres increases, the pores on the surface and inside the microspheres gradually increase;

[0131] Comparative Example 1 did not use the condensed phase separation and solvent replacement methods proposed in the present invention to prepare microspheres, so the obtained microspheres were solid microspheres with smooth surfaces;

[0132] Comparative Example 2 employed a solvent replacement step but did not employ a condensed phase separation step. Although the obtained material had a porous structure with high porosity, its formability was poor.

[0133] Comparative Example 3 adopts the method for preparing porous microspheres proposed in the present invention, but does not introduce the block copolymer. The pores on the surface are unevenly distributed and do not have a through-hole structure.

[0134] Test Example 2

[0135] The surface area and porosity of the materials obtained in Examples 1 to 8 and Comparative Examples 1 to 3 were measured using the N2 adsorption method. The particle size of the materials obtained in Examples 1 to 8 and Comparative Examples 1 to 3 was measured using an Anton Paar PSA1190 laser particle size analyzer.

[0136] Table 1

[0137] Material <![CDATA[Surface area (m 2 / g)]]> Porosity (%) <![CDATA[Density (g / cm 3 )]]> Particle size (μm) Example 1 112.5±1.3 91.3 0.21 93±3 Example 2 132.5±2.5 95.2 0.15 79±5 Example 3 101.7±3.2 83.9 0.27 84±2 Example 4 97.6±0.9 78.8 0.33 99±7 Example 5 110.2±1.5 92.1 0.19 104±5 Example 6 114.0±2.1 88.0 0.23 98±4 Example 7 109.9±0.8 86.2 0.24 102±8 Example 8 110.4±0.9 90.9 0.22 98±2 Comparative Example 1 0.1±0.04 0.4 1.4 125±3 Comparative Example 2 33.5±11.0 96.2 0.09 - Comparative Example 3 105.0±0.8 90.5 0.16 109±7

[0138] As shown in Table 1, the porous microspheres obtained in Examples 1-8 all have a greater surface area than Comparative Example 1. Comparative Example 2, due to its lack of a completely spherical structure, has a higher porosity but a lower surface area and density. Comparative Example 1, due to its solid, non-porous structure, has a higher density. The microspheres prepared using the method provided by the present invention possess high surface area and porosity, meeting the requirements of various applications.

[0139] Test Example 3

[0140] The porous microsphere samples from Examples 1, 6, and 7, and Comparative Examples 1 and 3, were spread onto a glass slide to a thickness of 5 mm. Static contact angle measurements were performed using a high-precision video contact angle meter. Experimental conditions: an injection volume of 2 μL at an injection rate of 1 μL / s. A water droplet was applied to the sample for 5 seconds. The contact angle was then recorded at the 5th second. The contact angle for each sample was recorded using the contact angle meter.

[0141] like Figures 11-15 In Examples 1, 6, and 7, as the content of block copolymer increases, the static water contact angle of the microsphere surface gradually decreases, and the surface hydrophilicity is enhanced. Comparative Example 1 is a solid polymer microsphere without a pore structure. From the contact angle test results, it shows a completely hydrophobic property. Comparative Example 3 is a porous polymer microsphere, but without the addition of block copolymer. Compared with Comparative Example 1, the surface contact angle is slightly reduced. It can be seen that in the preparation process of porous microspheres, the hydrophilicity of the obtained microspheres will change accordingly by changing the mass fraction of the block copolymer in the present invention.

Claims

1. A porous bio-based polymer microsphere comprising a mixture of a bio-based high molecular weight polymer P1 and a bio-based block copolymer P2, wherein the bio-based block copolymer P2 is a bio-based block copolymer having a hydrophilic end-capping group at one end and a hydrophobic end-capping group at the other end.

2. The porous bio-based polymer microspheres according to claim 1, characterized in that The bio-based polymer P1 is at least one selected from polylactic acid, polyglycolic acid, polylactic acid-glycolic acid copolymer, polycaprolactone, polydioxanone, and polyamino acid-derived carbonate; and / or, The weight average molecular weight of the bio-based high molecular weight polymer P1 is 1,000 to 600,000, preferably 4,000 to 100,000; and / or, The bio-based block copolymer P2 is selected from at least one of polylactic acid / polyethylene glycol block copolymers or derivatives thereof, polylactic acid-glycolic acid / polyethylene glycol block copolymers or derivatives thereof, polylactic acid / polyamino acid block copolymers or derivatives thereof, and polylactic acid-glycolic acid / polyamino acid block copolymers or derivatives thereof; and / or, The number average molecular weight of the bio-based block copolymer P2 is 1,000 to 100,000, preferably 5,000 to 50,000; and / or, The mass ratio of the bio-based block copolymer P2 to the bio-based high molecular polymer P1 is (0.01-2):1, preferably (0.05-1.5):

1.

3. A method for preparing the porous bio-based polymer microspheres according to any one of claims 1 to 2, comprising the steps of subjecting a dual organic solvent system containing the bio-based high molecular weight polymer P1 and the bio-based block copolymer P2 to phase separation, replacing the solvent with ultrapure water, and volatilizing the solvent.

4. The preparation method according to claim 3, characterized in that The specific steps include: (1) A bio-based polymer P1, an organic solvent A, and an organic solvent B are stirred to form a mixed solution (I); (2) adding the bio-based block copolymer P2 to the mixed solution (I) obtained in step (1) and fully dissolving it to obtain a mixed solution (II); (3) adding the mixed solution (II) obtained in step (2) to solvent C, homogenizing at high speed to obtain an emulsion, and storing at low temperature; (4) adding pre-cooled ultra-light water to the emulsion stored at low temperature in step (3) to perform a replacement operation to obtain a mixed solution (III); (5) The mixed solution (III) is post-treated to obtain the porous bio-based polymer microspheres.

5. The preparation method according to claim 4, characterized in that In the step (1): The organic solvent A is selected from at least one of halogenated alkanes, preferably at least one of dichloromethane and chloroform; and / or, The organic solvent B is selected from at least one of oxygen-containing polar organic solvents, preferably at least one of 1,4-dioxane, hexafluoroisopropanol, acetone, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide, more preferably at least one of 1,4-dioxane, hexafluoroisopropanol, and acetone; and / or, Based on 100 parts by weight of the bio-based polymer P1, the organic solvent A is 100 to 3000 parts, and the organic solvent B is 1 to 1000 parts; preferably, based on 100 parts by weight of the bio-based polymer P1, the organic solvent A is 100 to 2000 parts, and the organic solvent B is 5 to 750 parts; and / or, Natural polymers and / or bioactive ingredients are optionally added to the mixed solution (I). Preferably, the natural polymers and / or bioactive ingredients are selected from at least one of polypeptide proteins, water-insoluble drugs, bioactive factors, and natural polymers; and / or, the amount of the natural polymers and / or bioactive ingredients added is 0-1 wt%, preferably 0-0.2 wt%, of the bio-based polymer P1.

6. The preparation method according to claim 4, characterized in that In the step (1): The preparation of the mixed solution (I) specifically includes: Method (a): (a-1) dissolving the bio-based high molecular polymer P1 in an organic solvent A and stirring uniformly, preferably, the stirring temperature in step (a-1) is 10-20°C; (a-2) continuously adding an organic solvent B and stirring and mixing uniformly to obtain a mixed solution (I); preferably, the stirring temperature in step (a-2) is 20-30°C; or, Method (b): dissolving the bio-based high molecular polymer P1 in a mixed solvent of organic solvent A and organic solvent B and stirring uniformly to obtain a mixed solution (I). Preferably, the stirring temperature in method (b) is 10-30°C.

7. The preparation method according to claim 3, characterized in that In the step (2): The mass ratio of the bio-based block copolymer P2 to the bio-based high molecular polymer P1 is (0.01-2):1, preferably (0.05-1.5):1; and / or, The dissolving temperature is 10-35°C.

8. The preparation method according to claim 4, characterized in that In the step (3): The solvent C is selected from water or a polymer solution. The polymer solution is preferably an aqueous solution of at least one of polyethylene glycol, polyvinyl alcohol, water-soluble cellulose, water-soluble chitosan, and gelatin. More preferably, the mass percentage concentration of the polymer in the polymer solution is 0.1% to 5%, further preferably 0.5% to 1%; and / or, The mass ratio of the mixed solution (II) to the solvent C is 1:(1-10), preferably 1:(3-6); and / or, The stirring speed of the high-speed homogenization is 800 to 2000 ppm, preferably 1000 to 1500 ppm; and / or, The cryopreservation temperature is -70 to 0°C, preferably -15 to 0°C; and / or, The low-temperature storage time is 0.5 to 5 hours, preferably 1 to 3 hours.

9. The preparation method according to claim 4, characterized in that In the step (4): The mass ratio of the emulsion to ultra-light water is (1-20):1, preferably (1-5):1; and / or, The temperature of the ultra-light water is 2-4°C; and / or, The operation process of replacing the solvent with ultra-light water is as follows: ultra-light water is added to the emulsion stored at low temperature, soaked for 3 to 6 hours, and then centrifuged; the lower layer of material is removed and ultra-light water is added to repeat the soaking and centrifugation operations until no oily matter is left after soaking with ultra-light water, thereby obtaining a mixed solution (III).

10. The preparation method according to claim 4, characterized in that In the step (5): The post-treatment includes the steps of heating, stirring, filtering, washing and drying; preferably, The heating and stirring conditions are 55-65° C. and stirring for 2-6 hours; and / or, The cleaning solution used for the cleaning is selected from at least one of hydrochloride buffer, borate buffer, nitrate buffer, sulfate buffer, phosphate buffer, citrate buffer, carbonate buffer, acetate buffer, barbiturate buffer, and Tris buffer; and / or, The drying is freeze drying or vacuum drying. Preferably, the freeze drying conditions are -80 to -30°C and the drying time is 12 to 48 hours, and / or the vacuum drying conditions are 30 to 50°C and the drying time is 6 to 24 hours.

11. A porous bio-based polymer microsphere according to any one of claims 1 to 3 or a porous bio-based polymer microsphere obtained by the preparation method according to any one of claims 4 to 10, characterized in that: The porous bio-based polymer microspheres have a particle size of 5 to 500 μm, a pore size of 0.01 to 50 μm, and a specific surface area of ​​90 to 150 m 2 / g, and the porosity is 75-99%.

12. Use of the porous bio-based polymer microspheres according to claim 11 in adsorption materials, carrier materials, and scaffold materials.

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