RU2303580C2 - Method for manufacturing hydroxyapatite ceramics with bimodal distribution of pores - Google Patents

Abstract

FIELD: medicine, orthopedics, oral surgery, surgical stomatology.

SUBSTANCE: the present innovation refers to the system of delivering medicinal preparations and could be applied for filling in osseous defects or as a matrix for cell cultures. Porous hydroxyapatite ceramics with bimodal distribution of pores contains thin intragranular (under 10 mcm diameter) and large-scale interpenetrating intergranular pores, the size being above 100 mcm, at total quantity of about 41-70 rot.%. The method deals with manufacturing spherical granules of about 400-600 mcm diameter that contain hydroxyapatite powder and gelatin, pressing these spherical granules under 10-100 MPa pressure and thermal treatment at about 900-1250°C at keeping from 30 to 300 min. The innovation enables to create ceramics with bimodal distribution of pores.

EFFECT: higher efficiency of manufacturing.

2 cl, 1 tbl

Description

The invention relates to the field of ceramic materials for medicine, namely to traumatology and orthopedics, maxillofacial surgery and surgical dentistry, and can be used for the manufacture of materials designed to fill bone defects.

Ceramics for medical purposes should have interpenetrating pores with a diameter of at least 100-135 microns to ensure access of blood to contact surfaces, as well as germination and fixation of bone tissue [1]. Pores smaller than 50 microns are also necessary because they contribute to increased protein adsorption and adhesion of osteogenic cells.

A large number of studies are known on the technology of porous ceramics based on hydroxyapatite. Porous ceramics are obtained mainly by the method of burnable additives; impregnation and subsequent firing of organic (polyurethane) sponges, or foaming, for example, with the introduction of hydrogen peroxide [2-7]. Moreover, porosity, for example, when using sodium dodecylbenzenesulfonate reaches up to 50-60%, and in the case of glycine or agar-agar - about 80% [8]. Coral (the main substance of CaCO ₃ ) is also used, which, during hydrothermal treatment, passes into hydroxyapatite (250 ° C, 24–48 h), while maintaining the initial microstructure and open porosity [9]. It is known to use gelatin in the preparation of hydroxyapatite – gelatin microgranules [10]. When heated above 160 ° C, the gelatin is removed, forming pores.

Closest to the proposed technical solution is a method of manufacturing a porous hydroxyapatite ceramic, comprising mixing a hydroxyapatite powder having a particle size of 63 microns, 25-37 wt.% Pore-forming additives - flour with a particle size of 0.04-0.2 microns, uniaxial and cold isostatic pressing the mixture and subsequent sintering at temperatures of 1200 and 1250 ° C [2]. The method allows to obtain ceramics with an open porosity of 22.8-44.0% and with an average pore size of from 0.51 to 1.94 microns. The disadvantage of this method is that it does not allow to obtain ceramics with bimodal porosity: large pores larger than 100 microns and thin pores smaller than 10 microns.

The technical result of the invention is a porous hydroxyapatite ceramic containing thin pores with a size of less than 10 microns and large interpenetrating pores with a size of more than 100 microns in an amount of from 41 to 70 vol.%.

To achieve a technical result, spherical granules with a diameter of 400-600 μm are made, containing hydroxyapatite powder and gelatin with a ratio of these components from 1: 0.1 to 1: 0.3, they form crude preforms by pressing to an open intergranular porosity of 30-54 vol. % and subjected to preform heat treatment at a temperature of from 900 to 1250 ° C for burning gelatin and sintering particles of hydroxyapatite powder inside the granules and sintering the granules with each other. As a result, ceramics with intragranular pores smaller than 10 microns in size, formed due to burning of gelatin, and intergranular pores larger than 100 microns in size, created by laying granules, are obtained.

Hydroxyalatite-gelatin granules are prepared by the suspension method using the effect of immiscible liquids. The slurry of hydroxyapatite in a 10% aqueous gelatin solution, with the ratio of components of 1: 0.1 to 1: 0.3, were dispersed with a paddle stirrer at a speed of 500 rpm it min ^-1 in the dispersing liquid medium immiscible with the aqueous solution of the biopolymer. Under the action of surface tension forces, spherical granules are formed. The granules are precipitated, washed and dried. By sieving on a set of sieves, a fraction of 500-1000 microns is isolated. The dried granules are poured into metal molds and subjected to uniaxial pressing under a pressure of 10 to 100 MPa to obtain crude samples. The samples are then dried in air for 24 hours and subjected to heat treatment at a temperature of 900-1250 ° C with exposure at this temperature from 30 to 300 minutes in an atmosphere of air.

The table below shows the properties of materials obtained under various process conditions.

When the ratio of the components is less than 1: 0.1 and more than 1: 0.3, it is not possible to obtain hydroxyapatite-gelatin granules.

Compaction is not achieved at a compaction pressure of less than 10 MPa, and at a pressure above 100 MPa, the pores have an average size of less than 50 μm, which is due to both the deformation of the raw granules and the compaction of their packaging.

At a heat treatment temperature below 900 ° C, sintering of the powder and granules of hydroxyapatite does not occur, and at a temperature above 1250 ° C the porosity sharply decreases.

Information sources

1. Hing K.A., Best S.M., Tanner K.A., Bonfield W., Revell P.A. Quantification of bone ingrowth within bone derived porous hydroxyapatite implants of varying density // J. Mater. Sci. Mater. Med. 1999. V.10, No. 10/11. R.663-670.

2. Slosarzyk A., Stobierska E., Paszkiewicz Z. Porous hydroxyapatite ceramics // J. Mater. Sci. Lett. 1999. No. 18. P.1163.

3. Yamasaki N., Kai T., Nishioka M., Yanagisawa K. et al. Porous hydroxyapatite ceramics prepared by hydrothermal hot-pressing // J. Mater. Sci. Lett. 1990. V. 9, No. 10. P.1150

4. Tanner K.E., Downes R.N., Bonfield W. Clinical application of hydroxyapatite reinforced polyethylene // British Ceram. Trans. 1994. No3. P.104-107.

5. Liu D. Preparation and characterization of porous HA bioceramic via a slip-casting route // J. Ceram. Intern. 1997. V.24. P.441-446.

6. Engin NO, Tas AC Preparation of porous Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ and β-Ca ₃ (PO ₄ ) ₂ bioceramics // J. Am. Ceram. Soc. 2000. No. 7. P.1581-1584.

7. Sepulveda P., Ortega F.S., Innocentini M.D.M., Pandolfelli V.C. Properties of highly porous hydroxyapatite obtained by the gel casting of foams // J. Am. Ceram. Soc. 2000. V.83, No. 12. P.3021-3024.

8. Orlovsky V.P., Sukhanova G.E., Ezhova Zh.A., Rodicheva G.V. Hydroxyapatite bioceramics // J. Vses. Chem. about them D.I. Mendeleev. 1991. Vol. 36, No. 10. S.683-690.

9. Suchanek W., Yoshimura M. Processing and properties of HA-based biomaterials for use as hard tissue replacement implants // J. Mater. Res. Soc. 1998. V.13, No. 1. P.94-103.

10. RU 2235061 C1, 08.27.2004.

Table.
The content of open porosity and pore size distribution of sintered samples under various process conditions. The ratio of components, hydroxyapatite-
gelatin Pressing pressure
MPa Heat treatment temperature
° C Exposure min Open porosity
% The predominant pore size Intrapores Interpora Size, microns Amount, % Size, microns Amount,
% 1: 0.1 5 - - - - - - 1: 0.1 10 900 300 70 1-10 33 100-150 37 1: 0.1 10 1100 120 66 1-10 31 100-150 35 1: 0.1 thirty 1100 120 57 1-10 33 one hundred 24 1: 0.1 thirty 1250 60 49 1-5 thirty one hundred 19 1: 0.1 fifty 900 300 53 1-10 34 50-100 19 1: 0.1 fifty 1250 60 45 1-5 29th 50-100 16 1: 0.1 one hundred 1100 120 43 1-10 31 fifty 12 1: 0.1 one hundred 1250 60 41 1-5 29th fifty 12 1: 0.1 150 1000 180 43 1-10 34 0 9 1: 0.1 fifty 850 300 - - - - - 1: 0.1 fifty 1300 120 19 one fifteen 50-70 four 1: 0.2 fifty 1250 60 59 1-5 43 50-100 16 1: 0.3 fifty 1250 60 70 1-5 54 50-100 16 1: 0.05 - - - - - - - - 1: 0.4 - - - - - - - -

Claims (2)

1. A method of manufacturing a porous hydroxyapatite ceramic with a bimodal pore distribution containing thin intragranular pores with a diameter of less than 10 microns and large interpenetrating intergranular pores with a size of more than 100 microns, in a total amount of 41 to 70 vol.%, Which consists in the manufacture of spherical granules with a diameter of 400-600 microns containing hydroxyapatite powder and gelatin, pressing spherical granules under pressure from 10 to 100 MPa and heat treatment at temperatures from 900 to 1250 ° C with a holding time of 30 to 300 minutes. 2. A method of manufacturing a porous hydroxyapatite ceramic according to claim 1, characterized in that the spherical granules contain hydroxyapatite and gelatin in a mass ratio of components of 1: 0.1.