KR20100128870A - Preparation method of hydroxyapatite-chitosan composite coating layer using aerosol deposition and hydroxyapatite-chitosan composite coating layer with enhanced bioactivity - Google Patents

Abstract

PURPOSE: A preparation method of a hydroxyapatite-chitosan composite coating layer is provided, which allows good cohesive power by coating a hydroxyapatite-chitosan composite coating layer on a substrate at the room temperature. CONSTITUTION: A preparation method of a hydroxyapatite-chitosan composite coating layer comprises: a step of heat-treating hydroxyapatite material powder; a step of manufacturing composite powder by dry milling heat-treated hydroxyapatite powder and chitosan powder; and a step of coating hydroxyapatite-chitosan composite powder on a substrate by an aerosol deposition method.

Description

Preparation method of apatite-chitosan composite powder coating layer using aerosol deposition method and prepared by improving the bioactivity Apatite-chitosan composite coating layer using aerosol deposition and hydroxyapatite-chitosan composite coating layer with enhanced bioactivity}

The present invention provides a method for preparing an apatite hydroxide-chitosan composite powder coating layer using an aerosol deposition method, and an apatite hydroxide-chitosan composite powder coating layer having improved bioactivity.

Titanium or titanium alloys are the representative biomaterials that have been used in dental and orthopedic implants for decades. However, since titanium itself is not bioactive, it has a long bone formation period and a weak bond with surrounding bone tissue. In order to solve this problem, researches have been made to improve the reaction and adhesion with surrounding bone tissue by treating the surface of metal implants, and in particular, apatite hydroxide [HA, Ca ₁₀ (PO ₄ ) ₆ having excellent bioactivity and biosynthesis. When calcium phosphate-based ceramics, such as (OH) ₂ ], are used in the form of a coating on the surface of a metal implant, they have the advantage of being able to simultaneously obtain excellent biological properties of the ceramics and excellent mechanical properties of the metal.

Apatite hydroxide is a calcium phosphate-based ceramic, which is the main component of human bone, and has excellent bone conductivity, bioactivity, biocompatibility, protein adsorption, heavy metal adsorption, and antibacterial properties, so it is a filter for water purifier as well as bone substitute in orthopedics and dentistry. Although it is used as a material, there is a problem in that the molding process is difficult because it is not ductile and brittle.

On the other hand, chitosan is a biopolymer obtained by deacetylation of chitin obtained mainly from the shells of crustaceans in the ocean, and has excellent properties for use as a biomaterial such as biocompatibility, biodegradability, and nontoxicity. A wide range of applications are being made in various fields such as transporters and gene transporters.

For this reason, in recent years, in order to improve the biocompatibility of apatite hydroxide, many researches have been conducted on the preparation of a composite powder coating layer of apatite hydroxide and chitosan. Chitosan has a merit in that the composite powder coating layer having the optimal biological properties can be prepared by controlling the fractions of hydroxyapatite and chitosan because the rate of dissolution in vivo, adhesion of bone cells, and the like are different from those of apatite hydroxide. Korean Patent No. 500534 describes a process for forming a chitosan film by forming a chitosan film with a mixture containing polycarboxylic acid in a chitosan complex containing apatite hydroxide nanoparticles and treating it with methanol containing acetic anhydride, thereby preparing a chitin film. Biocompatible apatite hydroxide / chitosan composite fibers produced by spinning and methods for their preparation are described. In addition, the Republic of Korea Patent No. 482439 relates to a method for producing a bio-compatible film using chitosan and apatite hydroxide, the bio-compatible apatite / chitosan composites in combination with polycarboxylic acid using a wet spinning method A method of making chitosan composite fibers is described.

On the other hand, various methods have been used to coat a surface of a metallic material such as titanium with bioactive ceramics, such as conventional apatite hydroxide. Currently, the most widely known bioactive ceramic coating method is plasma spray coating method, but since it requires a high temperature of 10,000 degrees or more, it is impossible to composite coating of bioactive ceramics and materials such as polymers that are susceptible to high temperatures. To coat, you must use a method that allows coating at low temperatures. Currently, the main method for the composite coating of apatite hydroxide and chitosan is electrophoretic deposition. Electrophoretic deposition is a method of forming a coating layer of a desired composition from a colloidal solution on the substrate by using electrophoresis, but the deposition rate is slow and the adhesion between the coating layer and the substrate is weak, and post-heat treatment at high temperature to form a dense and sound coating layer Is necessary. As an example using electrophoretic deposition, a method of depositing a chitosan / apatite hydroxide composite coating layer on a titanium substrate (J Biomed Mater. Res. 66A (2003) 411-416) and a method of depositing an apatite-chitosan hydroxide composite coating layer on a stainless steel substrate Method (Materials Characterization 58 (2007) 339-348). However, when the apatite hydroxide-chitosan composite powder coating layer is manufactured, since the electrophoretic deposition cannot be performed after the electrophoretic deposition to prevent the deterioration of the chitosan, the adhesive strength is weaker than the coating layer prepared by the general electrophoretic deposition method, and the integrity of the coating layer is inferior. have.

Therefore, the inventors of the present invention while studying the manufacturing method of the apatite hydroxide-chitosan composite coating layer, dry apatite hydroxide and chitosan powder to prepare a hydroxide apatite-chitosan composite powder, using the aerosol deposition method has excellent adhesion and bioactivity Development of a method for producing this improved apatite hydroxide-chitosan composite powder coating layer was completed.

It is an object of the present invention to provide a method for preparing an apatite hydroxide-chitosan composite powder coating layer using an aerosol deposition method.

In addition, another object of the present invention is to provide an apatite hydroxide-chitosan composite powder coating layer with improved bioactivity.

In order to achieve the above object, the present invention comprises the steps of heat-treating the apatite hydroxide raw material powder (step 1);

Dry milling the apatite hydroxide powder and chitosan powder heat-treated in step 1 to prepare a composite powder (step 2); And

Provided is a method for preparing an apatite hydroxide-chitosan composite powder coating layer comprising the step (step 3) of coating the apatite hydroxide-chitosan composite powder prepared in step 2 on an aerosol deposition method.

In another aspect, the present invention provides a coating layer of the composite hydroxide apatite-chitosan composite powder improved bioactivity.

Apatite hydroxide-chitosan composite powder according to the present invention can be prepared by a simple dry mixing, the composite powder is coated on a substrate at room temperature by aerosol deposition method, dense, excellent adhesion and improved bioactivity Apatite-chitosan composite powder coating layer Since it is provided, it can be usefully used for medical implants.

The present invention comprises the step of heat-treating the apatite hydroxide raw material powder (step 1);

Dry milling the apatite hydroxide powder and chitosan powder heat-treated in step 1 to prepare a composite powder (step 2); And

It provides a method for producing a bio-apatite enhanced apatite-chitosan composite powder coating layer comprising the step (step 3) of coating the apatite hydroxide-chitosan composite powder prepared in step 2 by aerosol deposition.

Hereinafter, the method for preparing a hydroxyapatite-chitosan composite powder coating layer according to the present invention will be described in more detail step by step.

First, the step 1 according to the present invention is a step of heat-treating the apatite hydroxide raw material powder.

The heat treatment temperature of step 1 is preferably performed in the range of 1000-1200 ℃. If the heat treatment temperature is less than 1000 ° C., there is a problem that a green compact is formed during coating. If the heat treatment temperature exceeds 1200 ° C., a coating layer is not formed and the substrate is damaged.

Next, step 2 according to the present invention is a step of manufacturing a composite powder by dry milling the apatite hydroxide powder and chitosan powder heat-treated in the step 1.

The content of chitosan powder in step 2 is preferably 20% by weight or less based on the apatite hydroxide. If the content of the chitosan powder exceeds 20% by weight, there is a problem that the coating layer is not formed due to the excessive chitosan content. On the other hand, the lower limit of the chitosan content is not particularly limited, but is preferably 1% by weight or more from the viewpoint of preventing the bioactivity from deteriorating due to insufficient chitosan content.

In addition, the dry milling of the step 2 is preferably performed for 0.5-5 hours using a plastic ball, a metal ball and the like. If the milling time is less than 0.5 hours, there is a problem that the composite powder is not prepared because the mixing is not made completely, and when the milling time exceeds 5 hours, there is a problem that the coagulated powder occurs due to excessive milling.

Next, step 3 according to the present invention is a step of coating the apatite hydroxide-chitosan composite powder prepared in step 2 on the substrate by an aerosol deposition method.

The substrate of step 2 may use magnesium, titanium, magnesium alloy and titanium alloy.

The coating process of the apatite hydroxide-chitosan composite powder may be performed by a coating apparatus as shown in FIG. The apatite hydroxide-chitosan composite powder is introduced into the powder dispersion container 1, and the deposition chamber 2 is equipped with a magnesium, titanium, magnesium alloy or titanium alloy substrate 4. The vacuum pump 5 is operated so that the internal pressure of the deposition chamber 2 is 10 ⁻² Torr or less. The powder dispersion container 1 is shaken to cause the powder to scatter therein, and then a carrier gas is introduced. At this time, the size of the powder particles of the powder dispersion container 1 is made of a fine size in the range of 0.4-20 ㎛ to be scattered, it is preferable to put the carrier gas. The carrier gas is introduced into the deposition chamber 2 and the degree of vacuum in the deposition chamber after the carrier gas is introduced is preferably 0.1 to 10 Torr. In this case, oxygen, nitrogen, helium, argon or air may be used as the carrier gas. Since there is almost no change in the characteristics of the coating layer according to the type of gas, it is preferable to use a low-cost gas in consideration of productivity. Is preferably in the range of 0.1-50 L / min. The injected apatite-chitosan composite powder particles are dispersed through a nozzle (3) on a magnesium, titanium, magnesium alloy or titanium alloy substrate (4) located in a deposition chamber (2) maintained at room temperature in a vacuum atmosphere. A composite powder coating layer is formed.

In the method for producing the apatite hydroxide-chitosan composite powder coating layer, the nozzle 3 is spaced apart from the substrate 4 at intervals of about 1-20 mm, and the width of the nozzle 3 is about 0.1-10 mm. The length of the nozzle 3 is 5-25 mm.

The apatite hydroxide-chitosan composite powder coating layer prepared by the above-described manufacturing method not only has excellent adhesion to the substrate, but also improves the activity of alkaline posterase (ALP, an enzyme that is an indicator of bone formation).

The apatite hydroxide-chitosan composite powder coating layer according to the present invention has excellent adhesion and improved bioactivity, which can be usefully used for medical implants.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are merely to illustrate the invention, but the content of the present invention is not limited by the following examples.

Example 1 Preparation of Apatite Hydroxide-chitosan Composite Powder (chitosan content 5% by weight) and Coating Layer 1

(1) Preparation of Apatite Hydroxide-chitosan Composite Powder

Apatite hydroxide raw material powder having a commercially available average particle size of about 12 nm was heat-treated at 1050 ° C. for 2 hours to obtain a powder having an average particle size of about 2 μm. Apatite hydroxide powder and commercially available chitosan powder were added by 5% by weight, and dry milling with a plastic ball for 1 hour to prepare an apatite hydroxide-chitosan composite powder.

(2) Preparation of Apatite Hydroxide-chitosan Composite Powder Coating Layer

Apatite hydroxide-chitosan composite powder was put into a powder dispersion container, and a magnesium substrate was mounted in a vacuum chamber. The vacuum pump was operated to allow the internal pressure of the vacuum chamber to be 10 ⁻² Torr or less, and the carrier gas was introduced while the powder dispersion container was shaken to cause the internal powder to scatter. After the carrier gas was introduced, the degree of vacuum in the vacuum chamber was adjusted to 0.1-10 Torr. At this time, the gas flow rate was used 30 l / min, the gas supplied to the powder dispersion container was loaded with the apatite hydroxide-chitosan composite powder particles dispersed in the air to the nozzle unit in the vacuum chamber, the apatite-chitosan powder The particles were dispersed through a nozzle onto a substrate positioned in a vacuum chamber at room temperature in a vacuum atmosphere to prepare an apatite hydroxide-chitosan composite powder coating layer.

Example 2 Preparation of Apatite Hydroxide-chitosan Composite Powder (chitosan content 10 wt%) and Coating Layer 2

Apatite hydroxide-chitosan composite powder and a coating layer were prepared in the same manner as in Example 1, except that the content of the chitosan powder was added at 10% by weight.

Example 2 Preparation of apatite hydroxide-chitosan composite powder (chitosan content 20 wt%) and coating layer 3

Apatite hydroxide-chitosan composite powder and a coating layer were prepared in the same manner as in Example 1, except that the content of the chitosan powder was added at 20% by weight.

Comparative Example 1 Preparation of Apatite Hydroxide Coating Layer

A coating layer was prepared in the same manner as in Example 1, except that only apatite hydroxide was composed.

analysis

1.Apatite Hydroxide-Chitosan Composite Powder and Apatite Hydroxide Powders with Different Chitosan Contents Phase analysis

X-ray diffraction analysis (XRD, D-MAX 2200, Rigaku Co.) to analyze the phases of the apatite hydroxide-chitosan composite powder and the apatite hydroxide powder with different chitosan content, and the results are shown in FIG.

Referring to FIG. 2, apatite hydroxide-chitosan composite powder having a chitosan content of 5 wt%, apatite hydroxide-chitosan composite powder having a chitosan content of 10 wt%, and apatite hydroxide-chitosan composite powder having a chitosan content of 20 wt% and apatite hydroxide As a result of analyzing the powder phase, the powders showed similar patterns, and the phase change of the apatite hydroxide-chitosan composite powder according to the chitosan content was hardly observed.

2. Apatite Hydroxide-chitosan Composite Powder Coating Layer and Apatite Hydroxide Coating Layer with Different Chitosan Content Phase analysis

X-ray diffraction analysis (XRD, D-MAX 2200, Rigaku Co.) to analyze the phases of the apatite hydroxide-chitosan composite powder coating layer and the apatite hydroxide coating layer with different chitosan content, and the results are shown in FIG.

Referring to FIG. 3, the XRD peak by chitosan was not observed as in the powder analysis, and as the chitosan content was increased, the intensity of the apatite hydroxide peak was remarkably weakened. Accordingly, it can be seen that the deposition behavior of the coating layer or the microstructure of the coating layer is changed.

Experimental Example 1 Analysis of Chitosan Content in the Hydroxyapatite-Chitosan Composite Powder Coating Layers with Different Chitosan Contents

To analyze the chitosan content in the hydroxide apatite-chitosan composite powder coating layer having different chitosan contents, the following thermogravimetric analysis (TGA) was performed, and the results are shown in FIG. 4.

Thermogravimetric analysis experiments were performed by peeling the coating from the substrate and measuring the weight loss while applying heat.

As shown in FIG. 4, in the case of the apatite hydroxide coating layer, weight loss hardly occurred even when heated to 800 ° C., but in the case of the apatite hydroxide-chitosan composite powder coating layer, the weight was gradually decreased from 200 ° C. and the weight was about 500 ° C. The decline no longer occurred. The weight reduction of the apatite hydroxide-chitosan composite powder coating layer was caused by decomposition of chitosan by heating, and the composition of the composite powder and the composite coating layer was consistent with the chitosan fraction in each of the apatite hydroxide-chitosan composite powders. It can be seen that this coincides.

Experimental Example 2 Surface Microstructure Analysis of Apatite Hydroxide-chitosan Composite Powder Coating Layer and Apatite Hydroxide Coating Layer with Different Chitosan Content

In order to analyze the surface microstructures of the apatite hydroxide-chitosan composite powder coating layer and the apatite hydroxide coating layer having different chitosan contents, the results were observed with a scanning electron microscope (SEM, JSM-5800, Jeol Co.), and the results are shown in FIG. 5. .

Referring to FIG. 5, as the chitosan content is increased, the flat microstructure is represented, and Ra is a value indicating the surface roughness of the coating layer. As the chitosan content is increased, the value of Ra is gradually lowered so that the surface roughness is changed according to the composition of the composite coating layer. It can be seen that. In addition, it can be seen that the chitosan is present in the hydroxyapatite-chitosan composite powder coating layer due to the difference in the microstructure and the surface roughness.

Experimental Example 3 Adhesion Analysis of Apatite Hydroxide-Chitosan Composite Powder Coating Layer and Apatite Hydroxide Coating Layer with Different Chitosan Contents

In order to analyze the adhesion between the substrate of the apatite hydroxide-chitosan composite powder coating layer and the apatite hydroxide coating layer having different chitosan contents, the following experiment was performed, and the results are shown in Table 1 below.

Adhesion between the coating layer and the substrate is a very important factor in terms of long-term stability of the coating layer, the adhesion evaluation was based on the ISO 13779-4 standard. The coating layer was deposited on a titanium substrate having a diameter of 25 mm and a thickness of 1 mm, using a high strength thermosetting epoxy adhesive (3M Scotch-Weld Epoxy Adhesive 2214, 3M Corp., MA, USA) on the surface of the coating layer and the bottom of the titanium substrate, respectively. After bonding to the jig for measuring adhesion, the coating layer adhesion strength was measured through a tensile test using a universal testing machine (Instron series IX automated materials testing system, Instron Corp., MA, USA).

Yes Adhesion Strength (MPa) Comparative Example 1 27.7 ± 1.8 Example 1 27.5 ± 1.9 Example 2 26.6 ± 1.8 Example 3 24.6 ± 1.7

Referring to Table 1, Example 1 apatite hydroxide-chitosan composite powder coating layer of Example 1, apatite hydroxide-chitosan composite powder coating layer of Example 2 and apatite hydroxide-chitosan composite powder coating layer of Example 3 have an adhesion strength in the range of 24.6-27.5 MPa. It can be seen that the apatite hydroxide coating layer exhibits an adhesion strength in the range of 27.7 MPa.

Experimental Example 4 Analysis of Cell Proliferation Rate of Apatite Hydroxide-chitosan Composite Powder Coating Layer and Apatite Hydroxide Coating Layer with Different Chitosan Content

The following experiment was performed to evaluate the cell proliferation rate on the apatite hydroxide-chitosan composite coating layer and the apatite hydroxide coating layer.

Apatite hydroxide coating layer formed on the titanium substrate, apatite hydroxide-chitosan composite coating layer formed on the titanium substrate and precursor cells (MC3T3-E1, preosteoblast cell, ATCC, CRL-2593) on the uncoated titanium substrate, seeded and cultured Were compared and analyzed. The cells seeded on the coating layer were 10% fetal bovine serum in α-minimum essential medium (Join Bio Innovation, Seoul, Korea) and cell medium (Dulbecco's Modified Eagle Medium, Gibco, USA). , Gibco, USA) containing a culture medium was used, the cell culture was incubated at 37 ℃ 5% CO ₂ conditions. Cell proliferation evaluation was performed for 5 days by cytotoxicity measurement (MTS assay, CellTiter 96 Aqueous One Solution kit, Promega, Madison, USA), using a microplate reader (Biorad, Model 550, USA) at 490 nm wavelength The results are shown in Table 2.

Yes Cell proliferation rate Titanium substrate 1.131 Comparative Example 1 1.323 Example 1 1.272 Example 2 1.191 Example 3 1.311

Referring to Table 2, all coated specimens showed higher cell proliferation rate than those composed of titanium substrate only, and both the apatite hydroxide coating layer and the apatite hydroxide-chitosan composite powder coating layer showed high cell proliferation rates, and thus, the specimens were suitable for cell proliferation. Able to know.

Experimental Example 5 Analysis of Differentiation of Precursor Bone Cells (MC3T3-E1) of Apatite Hydroxide-Chitosan Composite Powder Coating Layer and Apatite Hydroxide Coating Layer with Different Chitosan Content

In order to evaluate the differentiation capacity of progenitor bone cells (MC3T3-E1, preosteoblast cell, ATCC, CRL-2593) on the apatite hydroxide-chitosan composite coating layer and the apatite hydroxide coating layer, alkaline postapartase (ALP) activity was measured by the following experiment.

Apatite hydroxide coating layer formed on a titanium substrate, apatite hydroxide-chitosan composite coating layer formed on a titanium substrate, and seeded osteoblasts (MC3T3-E1, preosteeoblast cell, ATCC, CRL-2593) on an uncoated titanium substrate, followed by incubation (ALP) activity evaluation experiments were performed. Evaluation of the differentiation ability of bone cells was performed for 10 days cultivation of alkaline posterase (ALP) activity, an indicator of early differentiation, and analyzed at 405 nm wavelength using a microplate reader (Biorad, Model 550, USA). The results are shown in Table 3.

Yes ALP activity Titanium substrate 0.343 Comparative Example 1 0.443 Example 1 0.467 Example 2 0.603 Example 3 0.597

Referring to Table 3, as the chitosan content was increased, alkaline postpartase (ALP) activity levels were improved, and it can be seen that the bioactivity was improved by the addition of chitosan.

1 is a schematic diagram of an apparatus for preparing apatite hydroxide-chitosan composite powder coating layer according to the present invention;

FIG. 2 is a graph showing the results of X-ray spectroscopy analysis of apatite hydroxide-chitosan composite powder and apatite hydroxide powder having different chitosan powder contents; FIG.

3 is a graph showing the results of X-ray spectroscopy analysis of apatite hydroxide-chitosan composite powder coating layer and apatite hydroxide coating layer having different chitosan powder contents;

4 is a graph showing the results of thermogravimetric analysis of the apatite hydroxide-chitosan composite powder coating layer and the apatite hydroxide coating layer having different chitosan powder contents; And

FIG. 5 is a scanning electron micrograph showing the surface microstructures of the apatite hydroxide-chitosan composite powder coating layer and the apatite hydroxide coating layer having different chitosan powder contents.

<Description of symbols for important parts of the drawings>

1: powder dispersion container

2: deposition chamber

3: nozzle

4: substrate

5: vacuum pump

6: x-y-z stage

7: carrier gas cylinder

Claims (6)

Heat-treating the apatite hydroxide raw powder (step 1); Dry milling the apatite hydroxide powder and chitosan powder heat-treated in step 1 to prepare a composite powder (step 2); And A method for producing a bio-activity enhanced apatite-chitosan composite powder coating layer comprising the step (step 3) of coating the apatite hydroxide-chitosan composite powder prepared in step 2 on the substrate by aerosol deposition. The method of claim 1, wherein the content of the chitosan powder of step 2 is 20 wt% or less with respect to the apatite hydroxide. The method of claim 1, wherein the aerosol deposition method of step 3 is carried out so that a carrier gas is introduced so that the apatite hydroxide-chitosan composite powder is scattered. The method of claim 1, wherein the substrate of step 3 is magnesium, titanium, magnesium alloy or titanium alloy. Apatite hydroxide-chitosan composite powder coating layer having improved bioactivity prepared by the method of claim 1. The apatite hydroxide-chitosan composite powder coating layer of claim 5, wherein the bioactivity is improved by coating the surface of the medical implant.

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