CN1562834A

CN1562834A - Degradable porous glass rack having bioactivity and preparation method

Info

Publication number: CN1562834A
Application number: CN 200410017240
Authority: CN
Inventors: 常江; 顾卫明; 钟吉品
Original assignee: Shanghai Institute of Ceramics of CAS
Current assignee: Kunshan Chinese Technology New Materials Co ltd; Shanghai Overseas Chinese Science And Technology Group Co ltd
Priority date: 2004-03-26
Filing date: 2004-03-26
Publication date: 2005-01-12
Anticipated expiration: 2024-03-26
Also published as: CN1269753C

Abstract

The compounds of glass frame are: (mol%) CaO 24-45, SiO2 34-50, Na2O 0-25, P2O5 5-17, MgO 0-5 and CaF2 0-1. Volume percentage of porosity is 40-80, aperture is 50-600 um. Biological active glas powder produced by melting method is used as raw material, adding organic or high polymer pore-forming agent with different granularities in, cellular material biscuit is formed by dry pressing or gel injection molding after mixing, the biscuit is roasted on proper raising temp. to produce degradated cellular biological active glass frame that mechanics strength, prosity and hole size can be controlled. There is hydroxyl kietyoite generated on surface of said frame after the frame is steeped in human body analog humor, it has good biological activity and can be used as hard tissue defect repairing material and cell frame material for in vitro bone tissue cultivating.

Description

Degradable porous bioactive glass bracket and preparation method thereof

Technical Field

The invention relates to a porous degradable bioactive glass scaffold material for hard tissue repair and serving as a tissue engineering cell scaffold and a preparation method thereof, belonging to the field of biological materials.

Background

Bioactive glass has been studied for over 30 years since Hench, 1971, first reported that bioactive glass can bind to bone tissue (1). Has been used clinically for over ten years as a repair of bone defects. Successful clinical application derives from its osteo-guided and bioactive properties that promote bone tissue growth. Many recent studies have shown that the degradation products of bioactive glass can promote the production of growth factors, promote the proliferation of cells, and activate the gene expression of osteoblasts. Furthermore, bioactive glass is currently the only artificial biomaterial that can bond to bone tissue and also bond to soft tissue. These unique characteristics make bioactive glass have great potential value as medical appliance in clinical application, and attract great attention in academia and industry. Despite its good biocompatibility and bioactivity, bioactive glass currently has only one granular form as a product for clinical use. As bone defect repair, a porous block-shaped scaffold material with certain mechanical strength is usually required to be filled and repaired clinically. Tissue engineering, now of great interest worldwide and developing more rapidly, also requires active porous scaffold materials as cell carriers.

Past studies have shown that the structure of materials, in addition to their composition, can largely directly affect the clinical utility of the materials. The porous block biological material with the pore diameter of 50-500 microns is most suitable for being used as a hard tissue repair material and a cell scaffold material. The porous biomaterial with the pore diameter within the range has the advantages of being beneficial to cell implantation or migration, tissue ingrowth and fusion of the material and living tissues so as to more effectively achieve the aims of repairing human tissue defects and tissue reconstruction. In addition, degradable porous biomaterials are an essential part in tissue engineering studies that have rapidly progressed in recent years. The porous scaffold is used as a cell carrier, cells grow in a matrix material, living tissues containing gene information of the body cells are constructed, and the living tissues are implanted into a human body to repair defective tissues and organs. Therefore, the degradable porous bioactive glass scaffold material has wide application prospect as a hard tissue defect repair material and a cell scaffold for in vitro bone tissue culture.

Ducheyne et al prepare CaO-SiO using hot pressing and inorganic salts such as calcium carbonate, sodium bicarbonate, etc. as pore formers₂-Na₂O-P₂O₅Porous bioactive glass scaffolds (U.S. patent application Nos. 5676720, 5811302) are used as cell scaffolds for culturing bone tissue in vitro. However, the hot pressing method adopted by the method has high production cost, and the residual components after sintering by using the inorganic salt as the pore-forming agent influence the composition of the material, so that the composition of the finished material is difficult to control. Yuan et al adopts hydrogen peroxide as a foaming agent, and prepares a porous 45S5 bioglass scaffold by sintering at 1000 ℃, and the scaffold prepared by the method also has bioactivity and can be bonded with bone tissues (J.biomed.Mater.Res; 58: 270-. However, according to our experimental results, sintering at 1000 ℃ causes the glass to crystallize largely and leads to degradation. In addition, the pore diameter and porosity of the material are difficult to control by using hydrogen peroxide as a foaming agent.

Mechanical strength is an important property of porous bioactive glass scaffold materials. Research results show that when the compressive strength is less than 1MPa, the applicability of the scaffold material is poor, and the scaffold material is extremely easy to damage in the use process of serving as a cell scaffold or bone injury repair material, so that the use effect is greatly influenced. In the prior patent literature, no report about the compressive strength index of the porous bioactive glass scaffold is found. Whether the compressive strength of the prepared porous bioactive glass bracket material can be controlled within a certain range according to the needs by process control or not so as to meet different application needs, thereby leading the purpose of the invention.

Disclosure of Invention

The invention aims to develop a novel porous bioactive glass scaffold which has excellent bioactivity and biodegradability, controllable pore diameter and porosity and through holes by optimizing a process, is used as a hard tissue defect repair material and a cell scaffold material for in vitro bone tissue culture, and has strength controlled within the range of 1-16MPa according to requirements so as to meet the requirements of development and clinical application of a new generation of biomaterials.

The porous bioactive glass bracket with different porosities, pore diameters, pore structures, compressive strengths and degradability is obtained by taking glass powder as a raw material, adding an organic pore-forming agent, and sintering at a proper temperature after dry pressing or slip casting. The chemical composition of the bioactive glass bracket is CaO 24-45%, SiO₂ 34-50％，Na₂O 0-25％，P₂O₅ 5-17％，MgO 0-5，CaF₂0 to 1 percent. The method provided by the invention can be used for preparing porous bioactive glass scaffolds with different shapes. The process control can ensure that partial calcium phosphate and/or calcium silicate crystals are precipitated from the bioactive glass bracket, thereby controlling the degradability and mechanical strength of the porous material according to requirements.

The porous bioactive glass bracket material has good bioactivity in human body simulated body fluid, can release silicon ions within a few hours, and deposits bone-like hydroxyapatite microcrystals on the surface. In addition, the porous bioactive glass also has degradability, and in-vitro solubility experiments show that the degradation rate is about 2-30% in a simulated body fluid environment for 5 days. Therefore, the porous bioactive glass scaffold material has good biological interface and chemical characteristics and good degradability.

The invention has another characteristic that the material has high porosity (40-80%) and proper pore diameter (50-600 microns) and proper mechanical strength (compressive strength of 1-16MPa) by controlling the process conditions.

In conclusion, the porous bioactive glass has unique advantages when being used as a hard tissue defect repair material and a cell scaffold material for in vitro bone tissue culture.

The specific implementation method of the invention is as follows:

1. preparation of materials

The bioactive glass powder is prepared by a melting method. The inorganic raw materials used were all analytically pure. The chemical reagent is weighed and mixed evenly according to the requirements of different components, then melted at the temperature of 1380-1480 ℃, and then cooled, crushed and sieved to obtain the glass powder with the granularity of 40-300 um. The porous bioactive glass bracket material is taken as a main raw material, and various porous bioactive glass bracket materials are prepared by respectively adopting different processes. The pore-forming agent adopted by the invention is one of organic or high polymer materials such as polyethylene glycol, polyvinyl alcohol, paraffin, polystyrene-divinylbenzene and the like, and the granularity range of the pore-forming agent is 50-600 microns. Mixing 20-70% (by mass) of pore-forming agent with a certain particle size range with bioactive glass powder, and then adopting two forming methods, wherein the first method is a dry pressing method, namely adding 1-5% of polyvinyl alcohol with the concentration of 5-10% into the mixture as a bonding agent, after uniformly mixing, performing dry pressing forming in a steel mould under the pressure of 2-20MPa to obtain the porous material biscuit, and finally calcining for 1-5 hours at the temperature of 750 plus 900 ℃ for sintering; the second method is a gel injection molding method, which comprises the steps of preparing an aqueous solution with the following mass percentage concentration, uniformly mixing the mixture and the aqueous solution according to the proportion of 30-60% by volume, adding 1-5% by mass of ammonium persulfate and 1-5% by mass of N, N, N 'and N' -tetramethylethylenediamine, uniformly stirring to obtain slurry with good fluidity and uniformity, pouring the slurry into a plastic or gypsum mold for gel injection molding, initiating the crosslinking reaction of the monomers at 30-80 ℃ for 1-10 hours, and drying at 100 ℃ for several hours to obtain the porous material biscuit. Then the porous bioglass material is obtained by removing plastic at 400 ℃ and calcining for 1-5 hours at 750-900 ℃.

2. Evaluation of Performance

2.1 mechanical Strength of porous Material

The series of samples obtained by the present invention were tested for compressive strength on an AG-I precision universal testing machine from Shimadzu corporation, Japan. The test speed of the sample is 5.0mm/min, and the test shows that the compressive strength of the porous material obtained by the invention can be controlled within the range of 1-16 MPa.

2.2 porosity of porous Material

The porosity of part of the samples obtained by the method is tested by an Archimedes method, and the pore morphology and the pore distribution are observed by a Scanning Electron Microscope (SEM). Tests show that the porosity of the porous material obtained by the invention can be controlled within the range of 40-80%.

2.3 evaluation of biological Activity

The porous material obtained by the invention is washed by deionized water and acetone in sequence, and then is dried to carry out in vitro solution bioactivity test. The solution used was human Simulated Body Fluid (SBF). SBF contains the same concentration of ions and clusters as human plasma. The composition of SBF is:

NaCl： 7.996g/L

NaHCO₃： 0.350g/L

KCl： 0.224g/L

K₂HPO₄.3H₂O： 0.228g/L

MgCl₂.6H₂O： 0.305g/L

HCl： 1mol/L

CaCl₂： 0.278g/L

Na₂SO₄： 0.071g/L

NH₂C(CH₂OH)₃： 6.057g/L

porous Material in SBF, the reaction conditions were 0.15g porous material, 30.0mL/day SBF, 37 ℃ incubator. After the porous material was soaked for 1, 3 and 7 days, respectively, the sample was taken out and washed with deionized water for SEM, fourier transform infrared spectroscopy (FTIR) and XRD tests, and the results are shown in fig. 3, fig. 4 and fig. 5, respectively. Biological activity experiments show that the porous bioactive glass scaffold material obtained by the invention can induce and generate bone hydroxyapatite on the surface, thereby showing that the materials have good biological activity.

2.4 evaluation of degradability

The porous material obtained by the invention is washed by deionized water and acetone and dried, and then is subjected to degradation experimental test. SiO released after soaking the porous material in SBF for different series of time₂The degradation rate and the degradability of the material are evaluated according to the percentage content. For example, PEG is used as a pore-forming agent, and the degradation rate of the porous bioactive glass bracket with the porosity of 40 percent in SBF for 5 days is 10 to 20 percent after dry pressing and calcining at 850 ℃, so that the porous bioactive glass material has good degradability.

Drawings

The foregoing will be better understood from the following detailed description of the invention taken in conjunction with the accompanying drawings. Wherein,

fig. 1 is a photograph showing the appearance of the prepared porous bioactive glass.

FIG. 2 is an optical microscope photograph of the cross section of the prepared porous bioactive glass.

FIG. 3 is an XRD pattern of porous bioactive glass prepared at different temperatures; the atlas shows that the materials prepared at different temperatures have different degrees of calcium silicate and calcium phosphate crystal precipitation; (a) bioactive glass powder before calcination, (b) bioactive glass bracket calcined at 800 ℃ and (c) bioactive glass bracket calcined at 850 ℃.

FIG. 4 is SEM images of a porous bioactive glass material of the present invention before soaking in SBF (human simulated body fluid) (A) and after soaking for 1 day (B) and 3 days (C); the photographs show that a large number of hydroxyapatite crystals appear on the surface of the material after being soaked for 1 day by SBF.

FIG. 5 is a graph of Fourier transform Infrared Spectroscopy (FTIR) spectra of porous bioactive glass materials of the present invention before soaking, after soaking for 0, 6 hours, 1, 3, and 7 days in SBF; analysis showed that after soaking in SBF for 6 hours, a peak of hydroxyapatite was present.

Detailed Description

The essential features and the remarkable advantages of the present invention will be further clarified by the following examples of the present invention, which are not intended to limit the present invention in any way.

Example 1:

the raw materials used are as described above.

Will analyze pure SiO₂，Na₂CO₃，CaCO₃，P₂O₅The raw materials are uniformly mixed according to a certain proportion, melted into a homogeneous melt at 1420 ℃, cooled, crushed and sieved to obtain the bioactive glass powder with the grain diameter of 40-300 um. The glass powder comprises 24.5 percent of CaO and SiO₂ 45％，Na₂O 24.5％，P₂O₅6％。

Mixing the bioactive glass powder with the granularity of 150-200 microns and the polyethylene glycol powder with the granularity of 200-300 microns according to the mass percentage of 60: 40, adding 6% polyvinyl alcohol solution as a binding agent, uniformly mixing, performing dry pressing forming under the pressure of 14MPa, and demolding to obtain a porous material biscuit. The biscuit is molded at 400 ℃ and then sintered at 850 ℃ for 2 hours to obtain the porous material of the invention, wherein the compressive strength is about 1.25MPa, and the porosity is about 56%. XRD contains Ca as shown in FIG. 2(C)₄P₂O₉And CaSiO₃。

The resulting porous material was soaked in SBF-simulated body fluid for 6 hours, 1, 3 and 7 days, and the soaked sample was subjected to evaluation of biological activity and degradability. The results in fig. 4 and 5 show that the porous bioactive glass material of the present invention forms a bone apatite layer on the surface of the material after being soaked in SBF, and has strong bioactivity. The biodegradation rate of the porous bioactive glass scaffold soaked in SBF for 5 days reaches 14%, which indicates that the porous bioactive glass scaffold obtained by the invention has good degradability and is expected to be used as a cell scaffold for hard tissue defect repair or in vitro bone tissue culture.

Example 2:

will analyze pure SiO₂，CaCO₃，Ca₃(PO₄)₂、MgCO₃、CaF₂The raw materials are uniformly mixed according to a certain proportion, melted into a homogeneous melt at 1450 ℃, cooled, crushed and sieved to obtain the bioactive glass powder with the grain diameter of 40-300 um. The glass powder comprises CaO 40.5% and SiO₂ 39.2％，MgO 4.5％，P₂O₅ 15.5％，CaF₂ 0.3％。

The obtained powder is mixed with the 300-600 micron polyvinyl alcohol powder according to the mass percentage of 50: 50 to obtain the solid mixture. Preparing an aqueous solution containing 20% of acrylamide, 2% of N, N ' -methylene bisacrylamide and 8% of polyacrylamide, uniformly mixing 10 g of the solid mixture with the aqueous solution according to the volume percentage of 50: 50, adding 3% by mass of ammonium persulfate and 3% by mass of N, N, N ' and N ' -tetramethyl ethylenediamine, uniformly stirring to obtain slurry with better fluidity, pouring the slurry into a mold for gel injection molding, initiating the crosslinking reaction of monomers for 3 hours at 60 ℃, drying at 100 ℃ for 12 hours, and then demolding to obtain the porous material biscuit. The biscuit is molded at 400 ℃ and then sintered at 850 ℃ for 2 hours to obtain the porous material of the invention, wherein the compressive strength is about 6.1MPa, and the porosity is about 55%. The degradation rate after 3 days of soaking in simulated body fluid is 78% (mass percent of dissolved Si). The properties of the porous material were evaluated as in example 1. Can be used as hard tissue defect repairing material.

Example 3:

the raw materials and the preparation method of the bioactive glass powder are the same as those in example 2.

Mixing bioactive glass powder with the granularity of 150-. The biscuit is molded at 400 ℃ and then sintered at 800 ℃ to obtain the porous material of the invention, wherein the compressive strength is about 1.5MPa, and the porosity is about 65%. The degradation rate after 3 days of immersion in simulated body fluid was 38% (mass% of dissolved Si). The properties of the porous material were evaluated as in example 1. Can be used as in vitro bone tissue culture cell scaffold.

Claims

1. A degradable porous bioactive glass bracket is characterized in that

(1) The glass bracket consists of 24-45 mass percent of CaO and 34-50 mass percent of SiO₂，0-25Na₂O，5-17P₂O₅0-5MgO and 0-1CaF₂；

(2) The glass bracket has a porosity volume percentage of 40-80;

(3) the aperture range of the glass bracket is 50-600 microns, and the pores are communicated with each other;

(4) the glass scaffold contains calcium phosphate and/or calcium silicate crystallites.

2. The degradable bioactive glass scaffold of claim 1, wherein the glass scaffold is formed from the group consisting of CaO24.5, SiO in weight percent₂45，Na₂O24.5 and P₂O₅6, the porosity volume percentage is 56, and the pore diameter is 50-600 microns.

3. The degradable bioactive glass scaffold of claim 1, wherein the glass scaffold is formed from CaO 40.5, SiO by mass percent₂ 39.2，MgO 4.5，P₂O₅15.5 and CaF₂0.3 composition, 55 volume percent porosity.

4. The method of preparing a degradable bioactive glass scaffold of claim 1, wherein it is prepared by either of the following two methods;

the dry pressing method comprises the following preparation process

(1) CaO24-45 and SiO in percentage by mass₂ 34-50，Na₂O 0-25，P₂O₅5-17, MgO 0-5 and CaF₂0-1, melting at 1380-1480 ℃, cooling, crushing and sieving to obtain glass powder with the granularity of 40-300 microns, wherein the glass powder is used as a main raw material of the bracket;

(2) adding 20-70 mass percent of pore-forming agent into the glass powder, wherein the pore-forming agent is one or two of polyethylene glycol, polyvinyl alcohol, paraffin or polystyrene-divinylbenzene, and the steps

(1) Uniformly mixing the middle glass powder;

(3) adding 1-5 mass percent of polyvinyl alcohol binder with the mass percent concentration of 5-10% into the mixture obtained in the step (2), uniformly mixing, forming in a steel mould under the pressure of 2-20MPa, and finally calcining at the temperature of 750 ℃ and 900 ℃ for 1-5 hours;

the gel injection molding method comprises the following process

(1) CaO24-45 and SiO in percentage by mass₂ 34-50，Na₂O 0-25，P₂O₅5-17, MgO 0-5 and CaF₂0-1, melting at 1380-1480 ℃, cooling, crushing and sieving to obtain glass powder with the granularity of 40-250 microns, wherein the glass powder is used as a main raw material of the bracket;

(1) Uniformly mixing the middle glass powder;

(3) uniformly mixing 20 mass percent of acrylamide monomer, 2 mass percent of N, N' -methylene bisacrylamide crosslinking agent and 5-10 mass percent of polyacrylamide dispersant aqueous solution with the mixture obtained in the step (2) according to the volume percentage of 30-60;

(4) adding 1-5 mass percent of ammonium persulfate, 1-5 mass percent of N, N, N 'and N' -tetramethyl ethylene diamine into the mixture obtained in the step (3), stirring to form uniform slurry, pouring the uniform slurry into a mold for gel injection molding, initiating monomer crosslinking reaction at the temperature of 30-80 ℃, and drying at 100 ℃ to prepare a biscuit;

(5) the biscuit obtained in the step (4) is firstly subjected to plastic removal at 400 ℃, and finally is calcined for 1-5 hours at 750-900 ℃.

5. The method of preparing a degradable bioactive glass scaffold of claim 4 wherein the pore former has a particle size in the range of 50 to 600 microns.

6. The method for preparing a degradable bioactive glass stent as claimed in claim 4, wherein the mold used in the gel forming preparation process is either a plastic mold or a gypsum mold, and the slurry crosslinking reaction time is 1 to 10 hours.

7. A degradable bioactive glass scaffold is used as a hard tissue defect repairing material or a cell scaffold for in vitro bone tissue culture.