Method for manufacturing hydroxyapatite ceramics with bimodal distribution of pores

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

 

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

Ceramics for medical purposes should be interpenetrating pore diameter of not less than 100-135 μm, in order to ensure the access of blood to the contact surfaces, as well as germination and fixation of bone tissue [1]. Pore size less than 50 microns are also necessary because they contribute to improving the adsorption of proteins and adhesion of osteogenic cells.

There are a large number of studies on the technology of porous ceramics based on hydroxyapatite. Porous ceramics comes primarily method burnable additives; impregnation and subsequent calcination of the organic (polyurethane) sponges or foam, for example with the introduction of hydrogen peroxide [2-7]. When this porosity, for example, when using dodecylbenzenesulfonate sodium reaches up to 50-60%, and in the case of glycine or agar-agar is about 80% [8]. Also use coral (the main substance of caso3), which during hydrothermal processing goes into hydroxyapatite (250°C, 24-48 h), preserving the original microstructure and open porosity [9]. Know the use of gelatin in the floor of the attachment of microgranules hydroxyapatite - gelatin [10]. When heated above 160°With gelatin is removed, forming pores.

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

The technical result of the invention is a porous hydroxyapatite ceramics containing thin size less than 10 microns and larger interpenetrating larger than 100 μm pores in the range from 41 to 70 vol.%.

To achieve a technical result produce spherical granules with a diameter of 400-600 microns containing powder of hydroxyapatite and gelatin when the ratio of these components is from 1:0.1 to 1:0.3, and form from them a raw workpiece pressing to open micronuclei porosity 30-54% vol. and subjecting the workpiece to heat treatment at a temperature of from to 1250° With debinding package of gelatin and sintering of the powder particles of hydroxyapatite within granules and primechanie granules between them. The result ceramics with vnutrepenialnymi pores smaller than 10 μm, formed by the burning of gelatin, and Microline pores larger than 100 μm, created by laying pellets.

Pellet hydroxiapatite-gelatin is produced by suspension polymerization using the effect of immiscible fluids. A suspension of hydroxyapatite in 10%aqueous solution of gelatin, when the mixing ratio from 1:0.1 to 1:0.3, and dispersed paddle stirrer at the speed of revolutions of 500 rpm-1in the dispersing liquid, immiscible with the aqueous solution of the biopolymer. Under the action of surface tension forces are formed granules of spherical shape. Granules precipitated, washed and subjected to drying. By sieving on a set of sieves allocate a fraction of 500-1000 μm. The dried granules are poured into a metal mold and subjected to uniaxial pressing under a pressure of 10 to 100 MPa with raw samples. The samples are then dried in air for 24 h and subjected to heat treatment at a temperature of 900-1250°aged at this temperature for 30 to 300 min in an atmosphere of air.

The table below shows the properties of the materials obtained in different modes of the process.

When autosizecomponents less than 1:0.1, and more 1:0,3 is not possible to obtain granules of hydroxyapatite - gelatine.

The compression pressure of less than 10 MPa is not achieved the compacting and at pressures above 100 MPa pores have an average size less than 50 microns, which is caused by deformation of the raw granules and seal packaging.

When the temperature of heat treatment below 900°does not occur With the sintering of the powder and granules of hydroxyapatite, and at temperatures above 1250°With sharply reduced porosity.

Sources of information

1. K.A. Hing, Best S.M., Tanner K.A., Bonfield W., P.A. Revell 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-670.

2. Slosarzyk A., Stobierska E., Z. Paszkiewicz 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. No. 3. 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 N.O., A.C. Tas Preparation of porous CA10(PO4)6(OH)2and β-CA3(RHO4)2bioceramics // J. Am. Ceram. Soc. 2000. No. 7. P.1581-1584.

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

8. Orlovsky VP, G. Sukhanov, Ezhova ZH.A., rodicheva CENTURY the Hydroxyapatite bioceramics// J. of Uses. chem. of the society to them. Mendeleev. 1991. T.36, No. 10. S-690.

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

10. EN 2235061 C1, 27.08.2004.

Table.

The contents of the open porosity and the pore size of sintered samples with different modes of process.
The ratio of the components, hydroxyapatite-

gelatin
Pressure,

MPa
The temperature of the heat treatment,

°
Extract, minThe open porosity,

%
The predominant pore size
IntraporeInterpore
Size, micronsNumber, %Size, micronsNumber,

%
1:0,15------
1:0,110900300701-1033100-15037
1:0,1101100120661-1031100-15035
1:0,130110012057 1-103310024
1:0,130125060491-53010019
1:0,150900300531-103450-10019
1:0,150125060451-52950-10016
1:0,11001100120431-10315012
1:0,1100125060411-5295012
1:0,11501000180431-103409
1:0,150850300-----
1:0,15013001201911550-704
1:0,250125060 591-54350-10016
1:0,350125060701-55450-10016
1:0,05--------
1:0,4--------

1. A method of manufacturing a porous hydroxiapatite ceramics with bimodal pore distribution, containing fine vnutrepenialnye diameter less than 10 microns and larger interpenetrating Microline pores larger than 100 μm in a total amount of from 41 to 70 vol.%, consisting in the production of spherical granules with a diameter of 400-600 microns containing powder of hydroxyapatite and gelatin, pressing spherical granules under pressure from 10 to 100 MPa, and heat treatment at temperatures from 900 to 1250°aged from 30 to 300 minutes

2. A method of manufacturing a porous hydroxiapatite ceramics according to claim 1, characterized in that the spherical granules contain hydroxyapatite and gelatin at a mass ratio of 1:0,1.



 

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