Phosphorylated amino acid composite microspheres as well as preparation and application thereof

Abstract

The invention discloses a phosphorylated amino acid composite microsphere, the phosphorylated amino acid composite microsphere comprises phosphorylated amino acid, a polymer binder, a liquid guide agent, a pH regulator and a divalent metal salt, the mass ratio of the phosphorylated amino acid and the liquid guide agent to the polymer binder to the pH regulator to the divalent metal salt is (900-920): (20-40): (30-40): (20-40), the mass ratio of the phosphorylated amino acid to the liquid guide agent is (930-980): (20-70). The invention also discloses a preparation method thereof. The bone adhesive prepared by mixing the phosphorylated amino acid composite microspheres prepared by the method and hydroxyapatite has the advantages that the coagulation time and the test bonding strength are in a better range.

Description

Technical Field

[0001] The present invention relates to phosphorylated amino acid composite microspheres and their preparation and application. Background Art

[0002] Tissue trauma surgeries often require the use of non-degradable materials such as staples and plates, which can negatively impact healing and require secondary surgery for removal. Soft tissue surgeries often require sutures, which are time-consuming, create new wounds, and are difficult to completely seal. Postoperative leakage of air and fluids, as well as exogenous infection, also hinder wound healing. A superior medical adhesive, capable of directly bonding wounds, offers an ideal solution.

[0003] Medical adhesives can be categorized into soft tissue adhesives and bone tissue adhesives based on their intended use. Soft tissue adhesives can be divided into biological adhesives (such as fibrin derivatives, mussel adhesion proteins, and gelatin) and chemical adhesives (such as cyanoacrylates, polyethylene glycols, and polyurethanes) based on their material properties. These adhesives are only suitable for soft tissue adhesion.

[0004] Bone tissue adhesives maintain their adhesive properties even in humid environments and exhibit excellent biocompatibility and degradation properties. Typically, bone tissue adhesives are composites of organic and inorganic materials. If the organic materials (such as starches, proteins, or other medical polymers) are not pretreated for liquid absorption and drainage, the outer layer will become sticky after absorbing liquid during use, preventing the inner dry material from contacting the liquid, significantly impacting the material's performance. Similarly, organic-inorganic composite bone adhesives require mixing before use, a process that involves ensuring uniform mixing of the solid and liquid phases. Inhomogeneous mixing can affect adhesive performance, such as difficulty in stirring and blending the adhesive and reduced adhesion. One approach to addressing the issues of uniform and sufficient material reaction is pre-poration (liquid drainage) of the material, including microsphere preparation and granulation. Emulsion processes can produce relatively ideal porous microspheres and offer significant advantages in particle size control, but they are complex, challenging to remove solvents, and prone to solvent contamination. While wet granulation or spray drying granulation methods are simple and effective, they require careful material design and screening to achieve the combined effects of pore formation and granulation. Summary of the Invention

[0005] The present invention is made in order to further increase the selection space of bone adhesives and provide a bone adhesive with better performance.

[0006] As one aspect of the present invention, it relates to a phosphorylated amino acid composite microsphere, which contains a phosphorylated amino acid, a polymer adhesive, a fluid conducting agent, a pH regulator and a divalent metal salt, wherein the mass ratio of (phosphorylated amino acid + fluid conducting agent): polymer adhesive: pH regulator: divalent metal salt is (900-920):(20-40):(30-40):(20-40), and the mass ratio of phosphorylated amino acid: fluid conducting agent is (930-980):(20-70).

[0007] In at least one embodiment, the phosphorylated amino acid refers to phosphorylated threonine, phosphorylated tyrosine, phosphorylated serine, phosphorylated hydroxyproline, or any combination thereof.

[0008] In at least one embodiment, the polymer binder is sodium carboxymethyl cellulose, hydroxyethyl cellulose, or any combination thereof.

[0009] In at least one specific embodiment, the fluid-conducting agent is sodium carboxymethyl starch, cross-linked sodium carboxymethyl cellulose, polyvinyl pyrrolidone, or any combination thereof.

[0010] In at least one specific embodiment, the pH adjuster is sodium carbonate, sodium bicarbonate, or any combination thereof. The pH adjuster is alkaline and can undergo an acid-base neutralization reaction with the acidic phosphorylated amino acid during the granulation process, thereby increasing the pH value of the system and generating a small amount of carbon dioxide and water, with the remaining sodium salt remaining in the system.

[0011] In at least one specific embodiment, the divalent metal salt is calcium citrate, calcium carbonate, calcium alginate, calcium glycerophosphate, or any combination thereof.

[0012] As another aspect of the present invention, it relates to a method for preparing the above-mentioned phosphorylated amino acid composite microspheres, the method comprising:

[0013] 1) Weigh the phosphorylated amino acid and liquid-dispersing agent, add 75-95% ethanol solution, mix thoroughly, remove the liquid, add 80-90% ethanol solution, remove the liquid, and dry to obtain a powder.

[0014] 2) Weigh a polymer binder, a pH adjuster, and a divalent metal salt, and mix them with the powder obtained in step 1) to obtain a mixed powder;

[0015] 3) Add the mixed powder to 60-75% ethanol solution at a volume / mass ratio of (45-55):100 (ml / g) for wet granulation;

[0016] 4) Drying to obtain dry granules;

[0017] 5) Sieve and take particles between 50 and 80 mesh, which are the phosphorylated amino acid composite microspheres.

[0018] As another aspect of the present invention, it relates to the use of the phosphorylated amino acid composite microspheres in the preparation of bone adhesive.

[0019] As another aspect of the present invention, it relates to a bone adhesive, which is prepared by mixing the above-mentioned phosphorylated amino acid composite microspheres with a calcium phosphate compound.

[0020] In at least one embodiment, the calcium phosphate compound is calcium phosphate or hydroxyapatite.

[0021] The present invention uses a wet granulation process to process the phosphorylated amino acid, which solves the problem of agglomeration when encountering water during use. It can be evenly mixed and reacted with other materials in an aqueous environment very quickly; it also provides a solution for the rapid dissolution of the phosphorylated amino acid. Wet granulation is low-cost, highly efficient, and environmentally friendly. Through innovative composite adhesives and liquid-conducting agents, the comprehensive needs of the granulation process and the subsequent application of the product are balanced, and the adhesion of the granulation process is optimized; by increasing the content of the wetting liquid (ethanol), the raw materials are pre-pored, which increases the porosity of the microspheres. A pH regulator containing carbonate is introduced during the granulation process. While adjusting the pH, the carbonate also decomposes in an acidic environment, releasing carbon dioxide, which increases the micropores of the material. The present invention also introduces a small amount of inorganic material that can undergo a coordination reaction. Through pre-reaction, the curing speed of the subsequent mixing reaction with the inorganic material can be adjusted. DETAILED DESCRIPTION

[0022] During the research process, the inventors found that when using amino acids for granulation, the concentration of ethanol used is positively correlated with the porosity of the product. However, when the ethanol concentration exceeds 70%, the adhesion of the material will be destroyed, resulting in the inability to granulate. By phosphorylating amino acids and adding appropriate amounts of adhesives and liquid-conducting agents, the inventors prepared a porous composite microsphere product with high porosity and the ability to quickly and evenly absorb water, and proposed this application.

[0023] In this application, unless otherwise specified, percentages are by mass.

[0024] Example 1: A phosphorylated threonine composite microsphere for bone adhesive component and its preparation process

[0025] 1. Weigh 950g of phosphorylated threonine and 50g of cross-linked sodium carboxymethyl cellulose and add 3000ml of 95% ethanol solution. Stir magnetically at 50rpm for 2 hours, then pass through a 200-mesh sieve. Add 2000ml of 80% ethanol solution to the retentate and stir magnetically at 50rpm for 1 hour. Pass through a 200-mesh sieve. Dry the retentate at 50°C for 3 hours until it becomes powdery. Pass through a 100-mesh sieve, and filter the filtered material.

[0026] 2. Weigh 20 g of 100-mesh hydroxyethyl cellulose powder, 40 g of 100-mesh sodium bicarbonate powder, and 40 g of 100-mesh glycerophosphate calcium powder. Place these together with 900 g of the filtrate from step 1 in a three-dimensional mixer and mix for 30 minutes to obtain a uniform powder.

[0027] 3. Granulation: Place the mixed powder in a wet granulator and add 65% ethanol solution at a volume / mass ratio of 45:100 (ml / g) to prepare wet granules. The granulation screen is 50 mesh.

[0028] 4. Drying: Dry the wet granules at 60°C for 75 minutes to obtain dry granules.

[0029] 5. Whole particles: Sieve and take particles between 50 and 80 mesh, which are the phosphorylated threonine complex microspheres.

[0030] 100 g of the prepared phosphorylated threonine composite microspheres were taken to determine the fluidity, and the fixed funnel method was used for detection, and the angle of repose was 34°; 5 g of the prepared phosphorylated threonine composite microspheres were taken and measured with a rapid moisture meter, and the moisture content of the particles was 4.3%, and the saturated liquid absorption rate was 2.6.

[0031] Method for determining the angle of repose: Use the fixed funnel method to determine the fluidity of the particles. Fix a glass funnel with an aperture of 5 mm vertically on an iron stand, and adjust the lower end of the funnel to 150 mm from the horizontal glass plate. Take 100 g of the sample to be tested and slowly pour it into the funnel, keeping the lower end of the funnel completely open. Stop when the particles naturally accumulate on the glass plate to form a cone and no particles flow. Use a protractor to measure the three different azimuth angles formed by the edge of the bottom surface of the cone and the top of the cone. Measure three times in parallel. The relative deviation should be less than 5%. Take the average value of 34° as the angle of repose.

[0032] Moisture content determination method: Use a halogen moisture meter for testing. Take 5.0±0.1g of sample and spread it evenly on the sample tray. Set the test temperature to 105°C and enable automatic detection mode. Constant weight is determined when the sample mass change rate is <0.1% / min. Perform three parallel measurements and take the average value. The absolute difference between the individual measured values and the average value should be ≤0.2%. The instrument automatically calculates and displays a moisture content of 4.3%. Saturated liquid absorption rate test: Weigh and peel a 20ml test tube. Pour 5g of composite microspheres into the bottom of the 20ml test tube. Add purified water until the material is saturated with water. Tilt the glass test tube downward and absorb any excess water with absorbent paper. Weigh the test tube. Calculate the saturated liquid absorption rate as (weight after absorption - 5) / 5.

[0033] 6. Weigh 5g of hydroxyapatite and 5g of the aforementioned phosphorylated threonine composite microspheres, mix them, add 3g of water, and stir until a paste-like state forms. This is the bone adhesive. It will begin to solidify after 6 minutes. The bond strength of the bone adhesive was tested to be 3.7 MPa. The bond strength test method is as follows: For the bond strength test, select two bovine bones (100mm long, 25mm wide, and 1.6mm thick). While in the paste-like state, apply the bone adhesive evenly to one of the bones to a thickness of 1mm, leaving a bonding surface 12.5mm long and 25mm wide. Secure the two bones together using a universal clamp. Then, incubate the sample in PBS at 37°C for 72 hours before testing. Bond strength testing was performed using a tensile testing machine at a crosshead speed of 1 mm / min. The sample was tested until failure, and the bond strength was determined based on the synthesized stress-strain curve. Three measurements were taken, and the average value was calculated.

[0034] The analysis and evaluation are mainly carried out from two aspects: physical properties of particles and clinical applicability:

[0035] The granules' physical properties were evaluated. The angle of repose was 34°, indicating good flowability and ensuring optimal mixing of the components during granulation. The moisture content was 4.3%, meeting the Chinese Pharmacopoeia's moisture content requirements for solid preparations (≤5%). This effectively prevents the risk of moisture absorption, agglomeration, or degradation during storage, ensuring stable storage. The granulation ethanol concentration was 65%, resulting in a saturated liquid absorption ratio of 2.6, which ensured a relatively good porosity and better control over the granulation process.

[0036] Clinical Applicability Evaluation, Setting Time, and Operability: The bone adhesive has an initial setting time of 6 minutes, shortening the curing time while maintaining the clinical operability window, meeting intraoperative shaping needs. Bond strength ≥ 2.0 MPa, meeting clinical tissue bonding requirements.

[0037] In summary, this example improves clinical operational efficiency by optimizing setting time. Subsequent examples will build on this knowledge by adjusting the phosphorylated amino acid content, the choice of composite binder / fluid-conducting agent, process parameters (such as ethanol concentration during granulation), or the carbonate ratio to adjust pH, and comparatively analyze their effects on fluidity, setting time, and bond strength.

[0038] Example 2: Phosphotyrosine Composite Microspheres for Bone Adhesive Components and Preparation Process

[0039] Weigh 980 g of phosphorylated tyrosine and 20 g of polyvinylpyrrolidone and add 3000 ml of 90% ethanol solution. Stir magnetically at 60 rpm for 1.5 hours and filter through a 200-mesh sieve. Add 2000 ml of 85% ethanol solution to the retentate and stir magnetically at 50 rpm for 1 hour. Spread the retentate evenly on a plate and dry at 65°C for 2 hours. Once the retentate becomes powder, pass it through a 100-mesh sieve and collect the filtered material.

[0040] 2. Weigh 30 g of hydroxyethyl cellulose (passed through a 100-mesh sieve), 30 g of sodium bicarbonate (passed through a 100-mesh sieve), and 20 g of calcium citrate (passed through a 100-mesh sieve) and place them in a three-dimensional mixer along with 920 g of the filtrate obtained in step 1. Mix thoroughly to obtain a mixed powder.

[0041] 3. Granulation: Place the mixed powder in a wet granulator and add 60% ethanol solution at a volume / mass ratio (ml / g) of 50:100 to prepare wet granules. The granulation screen is 50 mesh.

[0042] 4. Drying: Place the wet granules in a forced air drying oven at 50°C for 90 minutes to obtain dry granules.

[0043] 5. Whole particles: Sieve and take particles between 50 and 80 mesh, which are the phosphorylated tyrosine complex microspheres.

[0044] 100 g of the prepared phosphorylated tyrosine composite microspheres were taken to determine the fluidity using the fixed funnel method with an angle of repose of 35°; 5 g of the prepared phosphorylated tyrosine composite microspheres were taken to measure using a rapid moisture meter, and the particle humidity was 4.5% and the saturated liquid absorption rate was 2.7.

[0045] 6. Weigh 5g of tricalcium phosphate and 5g of the aforementioned phosphorylated tyrosine composite microspheres, mix them, add 3g of water, and stir until a paste-like state forms. This is the bone adhesive. It will begin to solidify after 5 minutes. The bond strength of the bone adhesive tested was 3.6 MPa.

[0046] Example 3: A Phosphorylated Serine Composite Microsphere for Bone Adhesive Component and Its Preparation Process

[0047] 1. Weigh 960g of phosphorylated serine and 40g of sodium carboxymethyl starch and add 2000ml of 85% ethanol solution. Stir magnetically at 80rpm for 1 hour, then filter through a 200-mesh sieve. Add the retentate to 3000ml of 90% ethanol solution and stir magnetically at 60rpm for 1.5 hours. Spread the retentate evenly on a plate and dry at 80°C for 1 hour until it becomes powdery. Pass the powder through a 100-mesh sieve, and remove the filtered material.

[0048] 2. Weigh 20 g of sodium carboxymethyl cellulose (passed through a 100-mesh sieve), 30 g of sodium bicarbonate (passed through a 100-mesh sieve), and 40 g of calcium alginate (passed through a 100-mesh sieve). Place them together with 910 g of the filtrate obtained in step 1 into a three-dimensional mixer and mix thoroughly to obtain a mixed powder.

[0049] 3. Granulation: Place the mixed powder in a wet granulator and add 60% ethanol solution at a volume / mass (ml / g) ratio of 55:100 to prepare wet granules. The granulation screen is 50 mesh.

[0050] 4. Drying: Place the wet granules in a forced air drying oven at 60°C for 75 minutes to obtain dry granules.

[0051] 5. Whole particles: Sieve and take particles between 50 and 80 mesh, which are the phosphorylated serine complex microspheres.

[0052] 50 g of the prepared phosphorylated serine composite microspheres were taken and tested by the fixed funnel method, and the angle of repose was 36°; 5 g of the prepared phosphorylated serine composite microspheres were taken and measured by a rapid moisture meter, and the particle humidity was 4.8% and the saturated liquid absorption rate was 2.5.

[0053] 6. Weigh 5g of tricalcium phosphate and 5g of the aforementioned phosphorylated serine composite microspheres, mix them, add 3g of water, and stir until a paste forms. This is the bone adhesive. It will begin to solidify after 7 minutes. The bond strength of the bone adhesive tested was 3.4 MPa.

[0054] Example 4: A fast-dissolving phosphorylated threonine composite microparticle and its preparation method

[0055] Weigh 960g of phosphorylated threonine and 40g of sodium carboxymethyl starch, add to 4000ml of 95% ethanol solution, magnetically stir at 60 rpm for 2 hours, and filter through a 200-mesh sieve. Add the retentate to 3000ml of 85% ethanol solution and magnetically stir at 40 rpm for 1 hour. Spread the retentate evenly on a plate and dry at 60°C for 2 hours until it becomes powdery. Pass the powder through a 100-mesh sieve and remove the filtered material.

[0056] 2. Weigh 20 g of sodium carboxymethyl cellulose, 30 g of sodium carbonate, and 950 g of the filtrate obtained in step 1, crush and sieve, and filter out the mixed powder that passes a 100-mesh sieve.

[0057] 3. Granulation: Place the mixed powder in a wet granulator and add 60% ethanol solution at a volume / mass (ml / g) ratio of 40:100 to prepare wet granules. The granulation screen is 50 mesh.

[0058] 4. Drying: Place the wet granules in a forced air drying oven at 55°C for 80 minutes to obtain dry granules.

[0059] 5. Whole particles: Screen the particles between 50 and 80 mesh to obtain the phosphorylated threonine composite microspheres. Using the fixed funnel method, the angle of repose is 33°. Using a rapid moisture meter, the moisture content is 4.1%, and the saturated liquid absorption rate is 2.3.

[0060] 6. Pour the phosphorylated threonine composite microspheres into pure water using a spatula. The microspheres will quickly absorb liquid from the water surface and sink to the bottom of the beaker without forming any white sticky patches. They will gradually dissolve at the bottom of the beaker.

[0061] Example 5:

[0062] 1. Weigh 930g of phosphorylated threonine and 70g of cross-linked sodium carboxymethyl cellulose and add 3000ml of 75% ethanol solution. Stir magnetically at 50 rpm for 2 hours, then filter through a 200-mesh sieve. Add the retentate to 2000ml of 80% ethanol solution and stir magnetically at 50 rpm for 1 hour. Filter through a 200-mesh sieve. Spread the retentate evenly on a plate and dry at 50°C for 3 hours. Once the powder is obtained, pass it through a 100-mesh sieve. Remove the filtrate.

[0063] 2. Weigh 40 g of hydroxyethyl cellulose (passed through a 100-mesh sieve), 40 g of sodium bicarbonate, and 20 g of calcium glycerophosphate; place these together with 900 g of the filtrate from step 1 in a three-dimensional mixer and mix thoroughly to obtain a mixed powder.

[0064] 3. Granulation: Place the mixed powder in a wet granulator and add 75% ethanol solution at a volume / mass (ml / g) ratio of 52 / 100 to prepare wet granules. The granulation screen is 50 mesh.

[0065] 4. Drying: Place the wet granules in a forced air drying oven at 56°C for 90 minutes to obtain dry granules.

[0066] 5. Whole granules: Sieve and select granules between 50 and 80 mesh, which are the phosphorylated threonine composite microspheres. Using the fixed funnel method, the angle of repose is 33°. Using a rapid moisture analyzer, the granules have a moisture content of 4.2% and a saturated liquid absorption rate of 2.4.

[0067] 6. Weigh 5g of hydroxyapatite and 5g of the aforementioned phosphorylated threonine composite microspheres, mix them, add 3g of water, and stir until a paste forms. This is the bone adhesive. It will begin to solidify after 6 minutes. The bond strength of the bone adhesive was tested to be 4.8 MPa.

[0068] Example 6:

[0069] 1. Weigh 940 g of phosphorylated threonine and 60 g of croscarmellose sodium and add to 3000 ml of 80% ethanol solution. Stir magnetically at 50 rpm for 2 hours, then filter through a 200-mesh sieve. Add the retentate to 2000 ml of 80% ethanol solution and stir magnetically at 50 rpm for 1 hour. Filter through a 200-mesh sieve. Spread the retentate evenly on a plate and dry at 50°C for 3 hours until it becomes powdery. Pass the powder through a 100-mesh sieve, and remove the filtered material.

[0070] 2. Weigh 30 g of hydroxyethyl cellulose (passed through a 100-mesh sieve), 20 g of sodium bicarbonate, and 30 g of calcium glycerophosphate; place these together with 920 g of the filtrate from step 1 in a three-dimensional mixer and mix thoroughly to obtain a mixed powder.

[0071] 3. Granulation: Place the mixed powder in a wet granulator and add 85% ethanol solution at a volume / mass (ml / g) ratio of 40 / 100 to prepare wet granules. The granulation screen is 50 mesh.

[0072] 4. Drying: Place the wet granules in a forced air drying oven at 60°C for 90 minutes to obtain dry granules.

[0073] 5. Whole granules: Sieve and select granules between 50 and 80 mesh, which are the phosphorylated threonine composite microspheres. Using the fixed funnel method, the angle of repose is 36°. Using a rapid moisture meter, the granules have a moisture content of 4.1% and a saturated liquid absorption rate of 2.8.

[0074] 6. Weigh 5g of hydroxyapatite and 5g of the aforementioned phosphorylated threonine composite microspheres, mix them, add 3g of water, and stir until a paste-like state forms. This is the bone adhesive. It will begin to solidify after 8 minutes. The bond strength of the bone adhesive tested was 1.6 MPa.

[0075] Example 7:

[0076] 1. Weigh 955g of phosphorylated threonine and 5g of cross-linked sodium carboxymethyl cellulose and add to 3000ml of 95% ethanol solution. Stir magnetically at 50 rpm for 2 hours, then filter through a 200-mesh sieve. Add the retentate to 2000ml of 80% ethanol solution and stir magnetically at 50 rpm for 1 hour. Filter through a 200-mesh sieve. Spread the retentate evenly on a plate and dry at 50°C for 3 hours. Once the powder is obtained, pass it through a 100-mesh sieve. Collect the filtered material.

[0077] 2. Weigh 20 g of hydroxyethyl cellulose (passed through a 100-mesh sieve), 20 g of sodium bicarbonate (passed through a 100-mesh sieve), and 30 g of calcium glycerophosphate (passed through a 100-mesh sieve). Place these together with 930 g of the filtrate from step 1 into a three-dimensional mixer and mix thoroughly to obtain a mixed powder.

[0078] 3. Granulation: Place the mixed powder in a wet granulator and add 70% ethanol solution at a volume / mass (ml / g) ratio of 50 / 100 to prepare wet granules. The granulation screen is 50 mesh.

[0079] 4. Drying: Place the wet granules in a forced air drying oven at 65°C for 60 minutes to obtain dry granules.

[0080] 5. Whole granules: Sieve and select granules between 50 and 80 mesh, which are the phosphorylated threonine composite microspheres. Test using the fixed funnel method with an angle of repose of 35°. Using a rapid moisture analyzer, the granules have a moisture content of 4.0% and a saturated liquid absorption rate of 2.6.

[0081] 6. Weigh 5g of hydroxyapatite and 5g of the aforementioned phosphorylated threonine composite microspheres, mix them, add 3g of water, and stir until a paste forms. This is the bone adhesive. It will begin to solidify after 7 minutes. The bond strength of the bone adhesive was tested to be 1.4 MPa.

[0082] In summary of the above examples, Example 4 mainly examines the dissolution-promoting effect of phosphorylated amino acids. Since no inorganic materials are used, the saturated liquid absorption rate of the prepared phosphorylated amino acid composite microspheres is only 2.3. Although the saturated liquid absorption rate is low, it effectively promotes the dissolution of phosphorylated amino acids; the setting time of the bone adhesive prepared in Example 6 is extended to 8 minutes, and the bone adhesive test bond strength is 1.6 MPa, which does not meet the clinical bonding requirements (greater than 2 MPa). This is because an ethanol concentration of 85% is used in the granulation process, which causes the particles to be loose, affecting the preparation effect of the adhesive; the setting time of the bone adhesive prepared in Example 7 is extended to 7 minutes, and the bone adhesive test bond strength is 1.4 MPa, which does not meet the clinical bonding requirements (greater than 2 MPa). This is because the proportion of the liquid-guiding agent cross-linked sodium carboxymethyl cellulose is reduced, resulting in loose particles, affecting the preparation effect of the adhesive; the above three examples all fail to meet the expectations of the invention, while the remaining examples all meet the expectations of the invention.

[0083] The phosphorylated amino acid composite microspheres prepared by the present invention have excellent fluidity (angle of repose ≤35°) and low hygroscopicity (moisture ≤5%), and have good liquid absorption and conduction properties. When used to prepare bone adhesive, they have the effects of rapid solidification (≤6 minutes) and bonding strength ≥2MPa, which can meet the clinical operation requirements and clinical bonding requirements of bone adhesive.

[0084] Summarizing Examples 1, 2, 3 and 5, it can be seen that the prepared phosphorylated amino acid composite microspheres contain phosphorylated amino acids, polymer adhesives, fluid-conducting agents, pH regulators and divalent metal salts, wherein the mass ratio of (phosphorylated amino acid + fluid-conducting agent): polymer adhesive: pH regulator: divalent metal salt is (900-920):(20-40):(30-40):(20-40), and when the mass ratio of phosphorylated amino acid: fluid-conducting agent is (930-980):(20-70), the angle of repose, particle moisture content and saturated liquid absorption rate of the prepared phosphorylated amino acid composite microspheres are all within a relatively good range, and the tested bonding strength of the bone adhesive mixed with the calcium phosphate compound is also within a relatively good range.

[0085] Summarizing Examples 1, 2, 3 and 5, it can be seen that the method for preparing phosphorylated amino acid composite microspheres includes:

[0086] 1) Weigh the phosphorylated amino acid and liquid-dispersing agent, add 75-95% ethanol solution, mix thoroughly, remove the liquid, add 80-90% ethanol solution, remove the liquid, and dry to obtain a powder.

[0087] 2) Weigh a polymer binder, a pH adjuster, and a divalent metal salt, and mix them with the powder obtained in step 1) to obtain a mixed powder;

[0088] 3) Add the mixed powder to 60-75% ethanol solution at a volume / mass ratio of 45-55:100 (ml / g) for wet granulation;

[0089] 4) Drying to obtain dry granules;

[0090] 5) Sieve and take particles between 50 and 80 mesh, which are the phosphorylated amino acid composite microspheres.

[0091] The phosphorylated amino acid refers to phosphorylated threonine, phosphorylated tyrosine, phosphorylated serine, phosphorylated hydroxyproline or any combination thereof.

[0092] The polymer adhesive refers to sodium carboxymethyl cellulose, hydroxyethyl cellulose or any combination thereof.

[0093] The fluid-conducting agent refers to sodium carboxymethyl starch (CMS-Na), cross-linked sodium carboxymethyl cellulose (CCMC-Na), polyvinyl pyrrolidone or any combination thereof.

[0094] The pH regulator refers to sodium carbonate, sodium bicarbonate or any combination thereof.

[0095] The divalent metal salt refers to calcium citrate, calcium carbonate, calcium alginate, calcium glycerophosphate or any combination thereof.

Claims

1. Phosphorylated amino acid composite microspheres, characterized in that: The phosphorylated amino acid composite microspheres contain phosphorylated amino acids, polymer adhesives, liquid conducting agents, pH regulators and divalent metal salts, wherein the mass ratio of (phosphorylated amino acids + liquid conducting agents): polymer adhesives: pH regulators: divalent metal salts is (900-920):(20-40):(30-40):(20-40), and the mass ratio of phosphorylated amino acids: liquid conducting agents is (930-980):(20-70).

2. The phosphorylated amino acid composite microspheres according to claim 1, characterized in that: The phosphorylated amino acid refers to phosphorylated threonine, phosphorylated tyrosine, phosphorylated serine, phosphorylated hydroxyproline or any combination thereof.

3. The phosphorylated amino acid composite microspheres according to claim 1, characterized in that: The polymer adhesive refers to sodium carboxymethyl cellulose, hydroxyethyl cellulose or any combination thereof.

4. The phosphorylated amino acid composite microspheres according to claim 1, characterized in that: The fluid-conducting agent refers to sodium carboxymethyl starch, cross-linked sodium carboxymethyl cellulose, polyvinyl pyrrolidone or any combination thereof.

5. The phosphorylated amino acid composite microspheres according to claim 1, characterized in that: The pH regulator refers to sodium carbonate, sodium bicarbonate or any combination thereof.

6. The phosphorylated amino acid composite microspheres according to claim 1, characterized in that: The divalent metal salt refers to calcium citrate, calcium carbonate, calcium alginate, calcium glycerophosphate or any combination thereof.

7. A method for preparing the phosphorylated amino acid composite microspheres according to any one of claims 1 to 6, characterized in that: The method comprises: 1) Weigh the phosphorylated amino acid and liquid-dispersing agent, add 75-95% ethanol solution, mix thoroughly, remove the liquid, add 80-90% ethanol solution, remove the liquid, and dry to obtain a powder. 2) Weigh a polymer binder, a pH adjuster, and a divalent metal salt, and mix them with the powder obtained in step 1) to obtain a mixed powder; 3) Add the mixed powder to 60-75% ethanol solution at a volume / mass ratio of (45-55):100 (ml / g) for wet granulation; 4) Drying to obtain dry granules; 5) Sieve and take particles between 50 and 80 mesh, which are the phosphorylated amino acid composite microspheres.

8. Use of the phosphorylated amino acid composite microspheres according to any one of claims 1 to 6 in the preparation of bone adhesive.

9. Bone adhesive, characterized in that The bone adhesive is formed by mixing the phosphorylated amino acid composite microspheres according to any one of claims 1 to 6 with a calcium phosphate compound.

10. The bone adhesive according to claim 9, characterized in that The calcium phosphate compound refers to calcium phosphate or hydroxyapatite.