CN1208281C - Preparation method of porous calcium silicate/β-tricalcium phosphate composite bioceramic material - Google Patents

Abstract

The invention relates to a preparation method of a bioactive and degradable porous calcium silicate/β-tricalcium phosphate composite bioceramic material, which belongs to the field of biomaterials. In the present invention, calcium silicate micropowder and β-tricalcium phosphate micropowder prepared by chemical methods are used as raw materials, mixed evenly according to the mass ratio of 10:90 to 99:1, and the mass ratio of added and composite micropowder is 3:7-6 : 4 organic or macromolecular pore-forming agent, mixed uniformly, dry-pressed or gel-cast to form a porous material green body, and finally calcined the green body at 900-1200° C. for 1-5 hours. The prepared porous bioceramic of the present invention has good biological activity, degradability, mechanical strength, suitable porosity and pore diameter, and fully meets the needs of hard tissue defect repair materials and cell scaffold materials for bone tissue culture in vitro. The process of the invention is simple and easy to implement and easy to popularize.

Description

Preparation method of porous calcium silicate/β-tricalcium phosphate composite bioceramic material

technical field

The invention relates to a preparation method of porous calcium silicate/β-tricalcium phosphate composite bioceramics with good biological activity, degradability and mechanical strength, belonging to the field of biological materials.

Background technique

In recent years, with the continuous development of tissue engineering, biomaterials, especially inorganic biomedical hard tissue repair and replacement materials, have received increasing attention and attention as the basic materials for the development of this discipline. Studies have found that among such materials, β-tricalcium phosphate biomaterials have better degradability but low bioactivity, while tricalcium silicate biomaterials are on the contrary, have very good bioactivity but mediocre degradability. Therefore, how to obtain a biomaterial with good bioactivity and degradability at the same time has become a problem before people.

Furthermore, in addition to the composition of biomaterials, the structure of biomaterials will directly affect the clinical application of the materials to a large extent. Previous studies have shown that porous bulk biomaterials with a pore size of 50-500 μm are most suitable as hard tissue repair materials and cell scaffold materials. The advantage of porous biomaterials with a pore size in this range is that it is conducive to cell migration, tissue ingrowth, and the fusion of materials and living tissues, so as to more effectively achieve the purpose of repairing human tissue defects and tissue reconstruction, and at the same time, it can also enhance the implantation of materials. and stability. Therefore, in the tissue engineering research that has developed rapidly in recent years, porous scaffolds are often used as cell carriers, and the degradability of the materials is used to allow cells to grow in the matrix material and construct living tissues containing the genetic information of the body cells. Implanted in the human body to repair defective tissues and organs.

P.N.de Aza (Biomaterials, 1997, 18:1285) from the University of San Diego in Spain mixed calcium silicate and tricalcium phosphate in a ratio of 60:40 by volume and placed them in a platinum crucible and heated them to 1500°C for 2 hours to obtain a uniform liquid phase. , then drop to 1410°C at a rate of 3°C/min, and then drop to 1390°C at a rate of 0.5°C/h. Thus, a composite bioceramic material containing calcium silicate and tricalcium phosphate co-melt structure is prepared. The material has good ability to form bone-like hydroxyapatite in simulated body fluid and human saliva immersion experiments. However, this method has the following disadvantages: the temperature during the sintering process of ceramics is relatively high (1390-1500° C.), and the time is relatively long (more than 40 hours), so the preparation process consumes a lot of energy and costs high. At the same time, the dense ceramic material prepared by this method is not suitable as a scaffold material in tissue engineering.

The AW glass developed by Kokubo et al. (J.Mater.Sci., 1986, 21:536) in Japan in the 1980s is a glass ceramic in which two crystal phases of apatite and calcium silicate are precipitated in the glass phase. . The material has good mechanical properties and biological activity but cannot be degraded. The research of Kokubo et al. also confirmed that in the simulated body fluid, a bone-like hydroxyapatite layer can be formed on the surface of CaO-SiO ₂ -based glass, but no bone-like hydroxyapatite layer is formed on the surface of CaO-P ₂ O ₅ -based glass.

Huang Xiang and others prepared calcium silicate/tricalcium phosphate composite powder by chemical method, and after dry pressing and isostatic pressing, they were calcined at 1300-1400°C to obtain calcium silicate/tricalcium phosphate with a volume ratio of 60:40. Composite bioactive ceramic material (Chinese patent application number: 02110847.1). Since the sintering temperature is much higher than that of calcium silicate and calcium phosphate, this method cannot prepare porous ceramics with large pores, and the obtained material only contains a small amount of micropores, and the pore diameter is only 1-2 microns. Such small micropores make it difficult for tissues and blood vessels to grow into the material, so it is not suitable as a cell scaffold material in tissue engineering. In addition, this invention does not make a clear evaluation of the degradation performance of the prepared material.

Contents of the invention

The purpose of the present invention is to develop a through-pore calcium silicate/β-tricalcium phosphate composite bioceramic with good biological activity, degradability and suitable mechanical strength, pore size and porosity through the optimization process Material. The material can be used as a hard tissue defect repair material and a cell scaffold material for bone tissue culture in vitro, so as to meet the needs of the development of a new generation of biomaterials.

The present invention is achieved through the following scheme:

The calcium silicate micropowder used in the present invention is prepared by chemical method using Ca(NO ₃ ) ₂ ·4H ₂ O and Na ₂ SiO ₃ ·9H ₂ O as raw materials. Chinese patent 02137248.9 has already recorded the preparation method of this powder. That is to prepare 0.1-1.0mol/L Ca(NO ₃ ) ₂ 4H ₂ O and Na ₂ SiO ₃ 9H ₂ O solutions, react with materials in equimolar ratio, and add Na ₂ SiO ₃ solution to Ca(NO ₃ ) ₂ In the solution, after adding the materials, continue to stir for 8-24 hours, filter and fully wash with deionized water and absolute ethanol to remove residual Na ⁺ ions, and the powder obtained by drying is calcined at 800°C-1000°C after ball milling 1-3 hours, to obtain β-CaSiO ₄ fine powder. The β-tricalcium phosphate micropowder used in the present invention is also prepared by chemical methods, and the specific methods can be found in the literature (Jarcho M, Bolen C HJMaterials Sci, 1976, 11: 2027-2035). The particle size of the above-mentioned calcium silicate and β-tricalcium phosphate is required to be 100nm-150μm.

Calcium silicate micropowder and β-tricalcium phosphate micropowder are mixed according to mass percentage of 10:90-99:1 to form composite micropowder. One or more of organic or polymer materials such as PEG (polyethylene glycol), PVA (polyvinyl alcohol), paraffin, polystyrene-divinylbenzene, etc. are selected as pore-forming agents, and the particle size is required to be 50- 700 microns. The mixture is obtained by mixing the pore-forming agent with the composite fine powder according to the mass ratio of 3:7-6:4.

After that, the following two molding methods can be adopted,

The first is the dry pressing method, that is, adding PVA (polyvinyl alcohol) with a mass percentage of 1-5% and a concentration of 1-10% to the above-mentioned mixture as a binder, after mixing evenly, press it in a steel mold at 2-30MPa The pressure of dry pressing is formed to obtain the porous material green body of the present invention.

The second method is the gel casting method, that is to prepare a mixed aqueous solution with the following mass percentage concentration, 10-30% acrylamide (AM) monomer, 0.5-10% N, N'-methylene bis Acrylamide (MBAM) cross-linking agent and 5-10% polyacrylamide (PMAA-NH4) dispersant, mix the above-mentioned mixture with the mixed aqueous solution in a volume ratio of 30:70-60:40, and add mass Ammonium persulfate with a percentage of 1-5% is added in an amount of 1-15% by volume, and then N, N, N', N'-tetramethylethylenediamine (TEMED) with a mass percentage of 1-5% is added. The volume percentage is 1-15%, and the slurry with better fluidity is obtained by stirring evenly. Pour the slurry into a plastic or plaster mold for gel casting, and initiate the cross-linking reaction of the monomer at 30-80°C 1- After 10 hours, it was dried and demolded to obtain the porous material green body of the present invention.

Finally, the green bodies obtained by the two processes are calcined at 900-1200° C. for 1-5 hours to obtain the porous material of the present invention.

This method makes the performance evaluation of porous material as follows:

1. Mechanical strength of porous materials

The compressive strength of the porous material sample obtained in the present invention is tested on the AG-I precision universal testing machine of Japan Shimadzu Corporation. The test speed of the sample is 5.0 mm/min, and the test shows that the compressive strength of the porous material obtained by the present invention is in the range of 2-80 MPa.

2. Porosity and pore structure of porous materials

We use the Archimedes method to test the porosity of some samples obtained in the present invention, and use an optical microscope to observe the pore shape and pore distribution. Tests show that the porosity of the porous material obtained by the invention is in the range of 40-85%; the size of the pores is distributed in the range of 50-600 microns and the distribution of the pores is uniform and connected.

3. Biological Activity Evaluation

The porous material obtained in the present invention is washed successively with deionized water and acetone, and then dried in the air to test the biological activity of the in vitro solution. The solution used is simulated body fluid (SBF; Simulated Body Fluid). SBF contains the same concentration of ions and ion clusters as human plasma. SBF consists of:

NaCl: 7.996g/L

NaHCO ₃ : 0.350g/L

KCl: 0.224g/L

K ₂ HPO ₄ .3H ₂ O: 0.228g/L

MgCl ₂ .6H ₂ O: 0.305g/L

HCl: 1.0mol/L

CaCl ₂ : 0.278g/L

Na ₂ SO ₄ : 0.071g/L

NH ₂ C(CH ₂ OH) ₃ : 6.057g/L

The porous material is in the SBF, and the reaction conditions are 0.15g porous material, 30.0mL/day SBF, and 37°C thermostat. After soaking the porous material for 1, 3, 5 and 7 days, the samples were taken out and washed with deionized water for SEM, Fourier Transform Infrared Spectroscopy (FTIR) and XRD tests. The results are shown in Figure 2, Figure 3 and Figure 4, respectively. Biological activity experiments show that the porous calcium silicate/β-tricalcium phosphate dual-phase composite bioceramic material can induce bone-like hydroxyapatite on the surface, thus indicating that these materials have biological activity.

4. Degradability evaluation

The porous composite material obtained in the present invention is successively washed with deionized water and acetone, dried, and then subjected to in vitro degradability test evaluation. We evaluate the degradability of the material by the percentage of Ca ²⁺ released or the weight loss of the material after immersing the porous material in tris(hydroxymethyl)aminomethane (Tris) buffer solution with a pH value of 7.25 for different time . The results show that the degradation rate of the porous composite material with the mass range of β-tricalcium phosphate in the range of 5%-80% is 10%-70% after soaking in Tris buffer for 7 days.

Description of drawings

The above can be better understood through the following drawings combined with the detailed description of the present invention. If the mass percentage of calcium silicate in the sample accounts for 30%, and the mass percentage of β-tricalcium phosphate accounts for 70%, the sample of this component is marked as W3T7, and the others are similar. in,

Fig. 1 is the SEM topography figure of pure calcium silicate (A) and pure β-tricalcium phosphate (B) of the present invention before soaking in SBF (simulated body fluid of human body).

Fig. 2 is the porous composite bioceramic of pure calcium silicate (A), W7T3 (B), W5T5 (C), W3T7 (D) and pure β-tricalcium phosphate (E) of the present invention respectively in SBF (human simulated body fluid) ) SEM image after soaking in 1 day.

Figure 3 is the Fourier Transform Infrared Spectrum (FTIR) graphs of the porous materials of pure calcium silicate (A) and W5T5 (B) of the present invention before soaking in SBF, after soaking for 1, 3 and 7 days.

Fig. 4 is respectively the XRD patterns of the porous materials of pure calcium silicate (A) and W5T5 (B) of the present invention soaked in SBF for several hours.

Fig. 5 is an optical microscope image of the porous composite material obtained in the present invention.

Based on the results of Figures 1-4, the new phase deposited on the surface of the material in Figure 2 is a bone-like hydroxyapatite layer. The results in Fig. 2 show that the bioactivity of this kind of composite porous ceramics increases with the increase of calcium silicate content. The results in Fig. 5 show that the pore distribution of the material prepared by applying the present invention is uniform and has through holes.

Detailed ways

The following are examples of the present invention, but the present invention is by no means limited to the examples.

Example 1:

Calcium silicate and β-tricalcium phosphate micropowder with a particle size of 45-75 μm after sieving are mixed by ball milling at a mass ratio of 50:50 to obtain a composite powder. According to the mass ratio of 60:40, the composite powder is mixed with the PEG powder with a particle size of 315-630 μm after sieving, and the PVA solution with a mass percentage of 2% and a concentration of 6% is added as a binder. 14MPa dry press forming, demoulding the green body of porous material.

The green body was kept at 1100°C for 3 hours to prepare the porous material of the present invention. The measured compressive strength is about 14MPa, the porosity is about 55%, and the degradation rate in Tris buffer solution for 7 days is about 27%.

The obtained porous material was soaked in SBF simulated body fluid for 1, 3, 5 and 7 days, and the soaked samples were evaluated for biological activity. Figure 1, Figure 2, Figure 3 and Figure 4 show that the porous biological material prepared by the present invention has excellent biological activity.

Example 2:

Calcium silicate and β-tricalcium phosphate micropowder with a particle size of 38-44 μm after sieving are mixed by ball milling at a mass ratio of 50:50 to obtain a composite powder. According to the mass ratio of 40:60, the composite powder is mixed with the PEG powder with a particle size of 315-630 μm after sieving, and a PVA solution with a mass percentage of 2% and a concentration of 6% is added as a binder. 14MPa dry press forming, demoulding the green body of porous material.

The green body was kept at 1100°C for 3 hours to prepare the porous material of the present invention. The measured compressive strength is about 2.5MPa, the porosity is about 75%, and the degradation rate in Tris buffer solution for 7 days is about 30%.

The biological activity evaluation of the material is the same as that in Example 1.

Example 3:

Calcium silicate and β-tricalcium phosphate micropowder with a particle size of 38-45 μm after sieving are mixed by ball milling at a mass ratio of 95:5 to obtain a composite powder. The composite powder is mixed with the PVA powder with a particle size of 300-600 μm after sieving at a mass ratio of 70:30 to obtain a solid mixture. The preparation mass percentage concentration is the AM of 20%, the MBAM of 2% and the mixed aqueous solution of 8% PMAA- _NH , by the ratio of volume ratio 50: 50, 10 grams of solid mixtures are mixed with above-mentioned mixed aqueous solution, add mass percent 3% ammonium persulfate, the addition is 6% by volume, and then 3% by mass of TEMED is added, and the addition is 8% by volume, and the slurry with better fluidity is obtained by stirring evenly, and the slurry is poured into plastic or Gel injection molding in a plaster mold, initiating a cross-linking reaction of monomers at 60° C. for 3 hours, and then drying and demoulding to obtain the porous material green body of the present invention.

The compact is kept at 1100° C. for 2 hours to prepare the porous material of the present invention with a compressive strength of about 75 MPa and a porosity of about 43%. The degradation rate in Tris buffer solution for 7 days is about 45%.

The biological activity evaluation of the material is the same as that in Example 1.

Example 4:

Calcium silicate and β-tricalcium phosphate micropowder with a particle size of 38-45 μm after sieving are ball milled and mixed at a mass ratio of 20:80 to obtain a composite powder. According to the mass ratio of 50:50, the composite powder is mixed with the PEG powder with a particle size of 315-630 microns after sieving, and a PVA solution with a mass percentage of 3% and a concentration of 6% is added as a binder. Dry pressing at 14MPa, demoulding the green body of porous material. The calcination system of the green compact is as in Example 1, and the compressive strength of the porous material of the present invention is about 5.6 MPa, and the porosity is about 65%. The degradation rate in Tris buffer solution for 7 days is about 16.3%.

The biological activity evaluation of the material is the same as that in Example 1.

Example 5:

Calcium silicate and β-tricalcium phosphate micropowder with a particle size of 38-45 μm after sieving are mixed by ball milling at a mass ratio of 80:20 to obtain a composite powder. According to the mass ratio of 50:50, the composite powder is mixed with the PEG powder with a particle size of 150-200 microns after sieving, and a PVA solution with a mass percentage of 3% and a concentration of 6% is added as a binder. Dry pressing at 14MPa, demoulding the green body of porous material. The calcination system of the green compact is as in Example 1, and the compressive strength of the porous material of the present invention is about 6 MPa, and the porosity is about 65%. The degradation rate in Tris buffer solution for 7 days is about 68%.

The biological activity evaluation of the material is as in Example 1.

Claims (7)

1, the preparation method of the porous calcium silicate of a kind of biologically active and degradation property/bata-tricalcium phosphate complex phase bioceramic material comprises the preparation of calcium silicate micro power and bata-tricalcium phosphate micro mist, it is characterized in that:

(a) be calcium silicate micro power and bata-tricalcium phosphate micro mist to be mixed into composite micro-powder in 20: 80～95: 5 by mass ratio;

(b) select for use in polyoxyethylene glycol, polyvinyl alcohol, paraffin, the polystyrene-divinylbenzene one or more as pore-forming material, be 3 by mass ratio: 7-6: 4 ratio mixes pore-forming material with composite micro-powder;

(c) add mass percent 1-5% in the mixture of step (b) gained, concentration is the polyvinyl alcohol of 1-10%, and after mixing, with the dry-pressing formed one-tenth biscuit of the pressure of 2-30MPa, last biscuit was at 900-1200 ℃ of temperature lower calcination 1-5 hour in punching block.

2, press the preparation method of the porous calcium silicate/bata-tricalcium phosphate complex phase bioceramic material of described a kind of biologically active of claim 1 and degradation property, it is characterized in that the granularity of described Calucium Silicate powder and bata-tricalcium phosphate requires to be 45-75 μ m.

3, press the preparation method of the porous calcium silicate/bata-tricalcium phosphate complex phase bioceramic material of claim 1 or 2 described a kind of biologically actives and degradation property, the granularity that it is characterized in that described pore-forming material is the 50-700 micron.

4, the preparation method of the porous calcium silicate of a kind of biologically active and degradation property/bata-tricalcium phosphate complex phase bioceramic material comprises the preparation of calcium silicate micro power and bata-tricalcium phosphate micro mist, it is characterized in that:

(a) be calcium silicate micro power and bata-tricalcium phosphate micro mist to be mixed into composite micro-powder in 20: 80～95: 5 by mass ratio;

(b) select for use in polyoxyethylene glycol, polyvinyl alcohol, paraffin, the polystyrene-divinylbenzene one or more as pore-forming material, be 3 by mass ratio: 7-6: 4 ratio mixes pore-forming material with composite micro-powder;

(c) the preparation mass percent concentration is the mixed aqueous solution of 10-30% acrylamide monomer, 0.5-10%N, N '-methylene-bisacrylamide linking agent, 5-10% poly amic acid dispersion agent;

(d) be 30 by volume: 70-60: 40 ratio mixes the mixed powder of step (b) gained and the mixed aqueous solution of step (c) gained, adding mass percent is the ammonium persulphate of 1-5%, add-on is the 1-15% of volume percent, add the N that mass percent is 1-5% again, N, N ', N '-Tetramethyl Ethylene Diamine, add-on is the 1-15% of volume percent, obtain slurry after stirring, pour slurry into plastics or gypsum mold inner gel moldings formed therefrom, and crosslinking reaction 1-10 hour of 30-80 ℃ of trigger monomer, again with the biscuit of the dry demoulding at 900-1200 ℃ of temperature lower calcination 1-5 hour.

5, press the preparation method of the porous calcium silicate/bata-tricalcium phosphate complex phase bioceramic material of described a kind of biologically active of claim 4 and degradation property, it is characterized in that the granularity of described calcium silicate micro power and bata-tricalcium phosphate micro mist requires to be 45-75 μ m.

6, press the preparation method of the porous calcium silicate/bata-tricalcium phosphate complex phase bioceramic material of claim 4 or 5 described a kind of biologically actives and degradation property, the granularity that it is characterized in that described pore-forming material is the 50-700 micron.

7, the porous calcium silicate/bata-tricalcium phosphate complex phase bioceramic material of a kind of biologically active that makes according to the described method of one of claim 1-6 and degradation property is as sclerous tissues's impairment renovation material and external osseous tissue culturing cell timbering material.

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