Whitlockite coating constructed on surface of calcium phosphate-based bioceramic substrate and preparation method therefor

Abstract

The present invention relates to a method for constructing a whitlockite coating on a surface of a calcium phosphate-based bioceramic substrate and a resulting coating, wherein the preparation method includes the following steps of: preparing pure calcium phosphate-based bioceramic powder firstly, then pre-firing, shaping and calcining the pure calcium phosphate-based bioceramic powder to obtain a calcium phosphate-based bioceramic substrate, placing the substrate in a solution containing Mg.sup.2+, then transferring the substrate to a high-temperature high-pressure reaction kettle for a hydrothermal reaction, and then cleaning and drying the sample to obtain a whitlockite coating.

Claims

1. A method for constructing a whitlockite coating on a surface of a calcium phosphate-based bioceramic substrate comprising the steps of: (1) pre-firing, shaping and calcining a pure calcium phosphate-based bioceramic powder to obtain the calcium phosphate-based bioceramic substrate, wherein the pre-firing is conducted at a temperature ranging from 700° C. to 900° C. for 2 hours to 4 hours, and the calcining is conducted at a temperature ranging from 900° C. to 1100° C. for 2 hours to 4 hours; (2) placing the calcium phosphate-based bioceramic substrate in a solution containing Mg.sup.2+, and then transferring the calcium phosphate-based bioceramic substrate to a reaction kettle for a hydrothermal reaction to obtain a sample, wherein the pH of the solution containing Mg.sup.2+ ranges from 5.4 to 7.4; the volume mass ratio of the solution containing Mg.sup.2+ to the calcium phosphate-based bioceramic substrate ranges from 0.3 L/g to 2.4 L/g; the temperature of the hydrothermal reaction ranges from 80° C. to 120° C., and the time of the hydrothermal reaction ranges from 6 hours to 5 days; and (3) taking out the sample after the hydrothermal reaction in step (2) from the reaction kettle, and then cleaning and drying the sample to obtain the whitlockite coating on the surface of the sample, wherein the chemical formula of the whitlockite is Ca.sub.18Mg.sub.2(HPO.sub.4).sub.2(PO.sub.4).sub.12.

2. The method according to claim 1, wherein the calcium phosphate-based bioceramic powder in step (1) is produced by chemical precipitation.

3. The method according to claim 1, wherein the calcium phosphate bioceramic in step (1) is one or more of tricalcium phosphate, hydroxyapatite, tetracalcium phosphate and dicalcium phosphate.

4. The method according to claim 1, wherein the pure calcium phosphate-based bioceramic powder in step (1) is shaped by dry pressing shaping, isostatic pressing shaping, plastic shaping, slip casting shaping or extrusion shaping.

5. The method according to claim 1, wherein the solution containing Mg.sup.2+ is a simulated body fluid (SBF), a phosphate buffer containing Mg.sup.2+, a magnesium chloride solution or a magnesium nitrate solution.

6. The method according to claim 1, wherein the cleaning in step (3) is performed with deionized water in sequence; and the drying is performed in a drying oven at a temperature of 40° C. to 50° C.

7. A whitlockite coating prepared by the method for constructing the whitlockite coating on the surface of the calcium phosphate-based bioceramic substrate according to claim 1.

8. A whitlockite coating prepared by the method for constructing the whitlockite coating on the surface of the calcium phosphate-based bioceramic substrate according to claim 2.

9. A whitlockite coating prepared by the method for constructing the whitlockite coating on the surface of the calcium phosphate-based bioceramic substrate according to claim 3.

10. A whitlockite coating prepared by the method for constructing the whitlockite coating on the surface of the calcium phosphate-based bioceramic substrate according to claim 4.

11. A whitlockite coating prepared by the method for constructing the whitlockite coating on the surface of the calcium phosphate-based bioceramic substrate according to claim 5.

12. A whitlockite coating prepared by the method for constructing the whitlockite coating on the surface of the calcium phosphate-based bioceramic substrate according to claim 6.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an X-ray diffraction (XRD) diagram of a whitlockite coating according to Embodiment 1 of the present invention.

(2) FIG. 2 is a field emission scanning electron micrograph (SEM) of the whitlockite coating in Embodiment 1 of the present invention.

(3) FIG. 3 is a field emission scanning electron micrograph (SEM) of a whitlockite coating in Embodiment 2 of the present invention.

(4) FIG. 4 is a field emission scanning electron micrograph (SEM) of a whitlockite coating in Embodiment 3 of the present invention.

DESCRIPTION OF THE EMBODIMENTS

(5) To better understand the present invention, the present invention is further described hereinafter with reference to the embodiment, but the protection scope claimed by the present invention is not limited to the scope shown in the embodiments.

Embodiment 1

(6) A chemical precipitation method was used, 21.2535 g of Ca(NO.sub.3).sub.2.4H.sub.2O and (NH.sub.4).sub.2HPO.sub.4 were placed in two beakers A and B according to a molar ratio (Ca/P) of 1.5:1, and respectively added with deionized water for full dissolution, a buffer in the beaker B was adjusted to a pH value of 9.0 by using ammonia water with a volume ratio of 1:1, and the solution in the beaker B was dropwise added into the breaker A, and continuously stirred. Meanwhile, a pH value in the dropwise adding process was controlled to be 6.8 by using ammonia water with a volume ratio of 1:1; after the dropwise adding, the mixture was continuously stirred for 12 hours, and then precipitates generated were washed with deionized water for three times and transferred to an oven at 80° C. for drying, and thus pure calcium phosphate bioceramic powder was prepared. The pure calcium phosphate bioceramic powder was pre-fired to 900° C., the temperature was kept for 3 hours, then the pre-fired calcium phosphate bioceramic powder was shaped by dry pressing, i.e., 0.05 g of calcium phosphate bioceramic powder was put into a mold, and a pressure was kept at 1.0 MPa for 2 minutes to obtain a calcium phosphate bioceramic substrate. The calcium phosphate bioceramic substrate was calcined to 1100° C., and the temperature was kept for 3 hours. Then the sample was placed in a simulated body fluid (SBF) with a pH of 7.4, wherein the SBF was prepared according to the following method: 8.035 g of NaCl, 0.355 g of NaHCO.sub.3, 0.225 g of KCl, 0.231 g of K.sub.2HPO.sub.4.3H.sub.2O, 0.311 g of MgCl.sub.2.6H.sub.2O, 39 ml of 1 M HCl solution, 0.292 g of CaCl.sub.2 and 0.072 g of Na.sub.2SO.sub.4 were sequentially added into 700 ml of deionized water, and continuously stirred until the sample was completely dissolved, then deionized water was added until the total volume reached 900 ml, then 0.618 g of tris and 1 M HCl solution were added; a pH of the solution was controlled to be 7.42 to 7.45 during the process, and adjusted to be 7.4 after the tris was added completely. Deionized water was added until the total volume reached 1000 ml, and the temperature was controlled to be 36.5° C. during the whole process. Then the sample was transferred to a high-temperature high-pressure reaction kettle for a hydrothermal reaction at 120° C., a volume mass ratio of the SBF to the calcium phosphate bioceramic substrate was controlled to be 2.4 L/g, and the reaction lasted for 4 days. The sample after the hydrothermal reaction was taken out of the reaction kettle, and washed by using acetone and deionized water in sequence; then, the sample was placed in a drying oven at 45° C. for drying to obtain a whitlockite coating on a surface of the sample. See FIG. 1 for X-ray diffraction (XRD) of the whitlockite coating obtained in the present embodiment, wherein x-ray diffraction peaks of the whitlockite coating are corresponding to a standard card one by one, the whitlockite coating has a good crystallinity and a high strength, thus indicating that the pure whitlockite coating is successfully prepared. The whitlockite coating prepared in the present embodiment has a uniform morphology and a uniform grain size, and is shown as a hexagonal plate morphology, and a field emission scanning electron micrograph (SEM) of the whitlockite coating is shown in FIG. 2.

Embodiment 2

(7) A chemical precipitation method was used, 21.2535 g of Ca(NO.sub.3).sub.2.4H.sub.2O and (NH.sub.4).sub.2HPO.sub.4 were placed in two beakers A and B according to a molar ratio (Ca/P) of 1.5:1, and added with deionized water for full dissolution, a buffer in the beaker B was adjusted to a pH value of 9.0 by using ammonia water with a volume ratio of 1:1, and the solution in the beaker B was dropwise added into the breaker A, and continuously stirred. Meanwhile, a pH value in the dropwise adding process was controlled to be 6.8 by using ammonia water with a volume ratio of 1:1; after the dropwise adding, the mixture was continuously stirred for 12 hours, and then precipitates generated were washed with deionized water for three times and transferred to an oven at 80° C. for drying, and thus pure calcium phosphate bioceramic powder was prepared. The pure calcium phosphate bioceramic powder was pre-fired to 800° C., the temperature was kept for 2 hours, then the pre-fired calcium phosphate bioceramic powder was shaped by dry pressing, i.e., 0.20 g of calcium phosphate bioceramic powder was put into a mold, and a pressure was kept at 2.0 MPa for 3 minutes to obtain a calcium phosphate bioceramic substrate. The calcium phosphate bioceramic substrate was calcined to 1000° C., and the temperature was kept for 2 hours. Then the sample was placed in a simulated body fluid (SBF) with a pH of 7.4, wherein the SBF was prepared according to the following method: 8.035 g of NaCl, 0.355 g of NaHCO.sub.3, 0.225 g of KCl, 0.231 g of K.sub.2HPO.sub.4.3H.sub.2O, 0.311 g of MgCl.sub.2.6H.sub.2O, 39 ml of 1 M HCl solution, 0.292 g of CaCl.sub.2 and 0.072 g of Na.sub.2SO.sub.4 were sequentially added into 700 ml of deionized water, and continuously stirred until the sample was completely dissolved, then deionized water was added until the total volume reached 900 ml, then 0.618 g of tris and 1 M HCl solution were added; a pH of the solution was controlled to be 7.42 to 7.45 during the process, and adjusted to be 7.4 after the tris was added completely. Deionized water was added until the total volume reached 1000 ml, and the temperature was controlled to be 36.5° C. during the whole process. Then the sample was transferred to a high-temperature high-pressure reaction kettle for a hydrothermal reaction at 120° C., a volume mass ratio of the SBF to the calcium phosphate bioceramic substrate was controlled to be 0.6 L/g, and the reaction lasted for 2 days. The sample after the hydrothermal reaction was taken out of the reaction kettle, and washed by using acetone and deionized water in sequence; then, the sample was placed in a drying oven at 45° C. for drying to obtain a whitlockite coating on a surface of the sample. The whitlockite coating prepared in the present embodiment has a uniform morphology and a uniform grain size, and is shown as a triangular plate morphology, and a field emission scanning electron micrograph (SEM) of the whitlockite coating is shown in FIG. 3.

Embodiment 3

(8) A chemical precipitation method was used firstly, 21.2535 g of Ca(NO.sub.3).sub.2.4H.sub.2O and (NH.sub.4).sub.2HPO.sub.4 were placed in two beakers A and B according to a molar ratio (Ca/P) of 1.5:1, and added with deionized water for full dissolution, a buffer in the beaker B was adjusted to a pH value of 9.0 by using ammonia water with a volume ratio of 1:1, and the solution in the beaker B was dropwise added into the breaker A, and continuously stirred. Meanwhile, a pH value in the dropwise adding process was controlled to be 6.8 by using ammonia water with a volume ratio of 1:1; after the dropwise adding, the mixture was continuously stirred for 12 hours, and then precipitates generated were washed with deionized water for three times and transferred to an oven at 80° C. for drying, and thus pure calcium phosphate bioceramic powder was prepared. The pure calcium phosphate bioceramic powder was pre-fired to 700° C., the temperature was kept for 4 hours, then the pre-fired calcium phosphate bioceramic powder was shaped by dry pressing, i.e., 0.15 g of calcium phosphate bioceramic powder was put into a mold, and a pressure was kept at 2.0 MPa for 2 minutes to obtain a calcium phosphate bioceramic substrate. The calcium phosphate bioceramic substrate was calcined to 900° C., and the temperature was kept for 4 hours. Then the sample was placed in a simulated body fluid (SBF) with a pH of 7.4, wherein the SBF was prepared according to the following method: 8.035 g of NaCl, 0.355 g of NaHCO.sub.3, 0.225 g of KCl, 0.231 g of K.sub.2HPO.sub.4.3H.sub.2O, 0.311 g of MgCl.sub.2.6H.sub.2O, 39 ml of 1 M HCl solution, 0.292 g of CaCl.sub.2 and 0.072 g of Na.sub.2SO.sub.4 were sequentially added into 700 ml of deionized water, and continuously stirred until the sample was completely dissolved, then deionized water was added until the total volume reached 900 ml, then 0.618 g of tris and 1 M HCl solution were added; a pH of the solution was controlled to be 7.42 to 7.45 during the process, and adjusted to be 7.4 after the tris was added completely. Deionized water was added until the total volume reached 1000 ml, and the temperature was controlled to be 36.5° C. during the whole process. Then the sample was transferred to a high-temperature high-pressure reaction kettle for a hydrothermal reaction at 80° C., a volume mass ratio of the SBF to the calcium phosphate bioceramic substrate was controlled to be 0.3 L/g, and the reaction lasted for 5 days. The sample after the hydrothermal reaction was taken out of the reaction kettle, and washed by using acetone and deionized water in sequence; then, the sample was placed in a drying oven at 50° C. for drying to obtain a whitlockite coating on a surface of the sample. The whitlockite coating prepared in the present embodiment has a uniform morphology and a uniform grain size, and is shown as a spherical morphology, and a field emission scanning electron micrograph (SEM) of the whitlockite coating is shown in FIG. 4.

(9) The embodiments above are preferred embodiments of the present invention, but the implementations of the present invention are not limited by the embodiments above. Any other amendment, modification, replacement, combination and simplification made without deviating from the spiritual substance and principle of the present invention shall be equivalent substitute modes, which are all included in the protection scope of the present invention.