Nanopatterned calcium phosphate ceramic material on basis of threecalciumphosphate-hydroxyapatite system for reconstruction of osteal defects

FIELD: medicine, pharmaceutics.

SUBSTANCE: it is described a nanopatterned calcium phosphate material on the basis of threecalciumphosphate-hydroxyapatite system for reconstruction of osteal defects. The invention concerns to the calcium phosphate ceramic materials intended for manufacturing of osteal implants and-or replacement of defects at various osteal pathologies. The material on the chemical compound is close to a natural osteal tissue (the structure corresponds to the threecalciumphosphate-hydroxyapatite system). The unique ultradisperse structure of a material is formed at the expense of use of initial calcium phosphate nanopatterned powders and the additive.

EFFECT: reception of a ceramic material with uniform structure with the average size of particles less than 100 nanometres.

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The invention relates to medicine, in particular calcium phosphate ceramic materials intended for the manufacture of bone implants and/or replacement of defects in various bone pathologies.

Calcium phosphates are the main elements of the bone and are widely used as materials for bone regeneration and production of solid bone implants used in orthopedic, maxillofacial surgery, etc. To the most used in medicine to calcium phosphates include tricalcium phosphate - CA3(RHO4)2(TCP) and hydroxyapatite - CA5(PO4)3HE (HA) or bi-phase materials based on the system TKF-HA. Biological and mechanical properties of calcium phosphate ceramics are determined by the phase composition and structure, which mainly depend on the firing temperature and the size of the original particles of the ceramic powder. One method to improve mechanical properties and reduce the sintering temperature of ceramics is the use of ceramic ultrafine powders with a particle size less than 1 micron.

(A.Tampieri, G.Celotti, F.Szontagh and E.Landi "Sintering and characterization of HA and TCP bioceramics with control of their strength and phase purity" J. of Materials Sciance: Materials in Medicine 8 (1997) 29-37) were obtained calcium phosphate materials based on TCP and HA powders with an average crystal size of 0.5 is km. The obtained materials were characterized by a crystalline structure with an average crystal size of 1-2 microns, a porosity of less than 7%. The disadvantage of this material was high firing temperature 1220-1300°C. in Addition, at temperatures above 1250°C, the decrease of the strength and partial decomposition of HA with the formation of toxic calcium oxide.

The closest technical solution and the achieved effect is calcium phosphate-based materials system tricalcium phosphate-hydroxyapatite (S.Raynaud, E.Champion*, D.Bernache-Assollant "Calcium phosphate apatites with variable Ca/P atomic ratio II. Calcination and sintering", Biomaterials 23 (2002) 1073-1080) obtained by sintering of nanocrystalline powders at a temperature of 1100-1150°C. In this work to reduce the sintering temperature managed through the use of nanocrystalline powders and method of hot pressing. This has resulted in bi-phase materials system TKF-HA, which was characterized by a fine structure with an average crystal 200 nm. The disadvantage of this pottery is a high firing temperature and the application of the method of hot pressing, resulting in a considerable rise in prices of finished products.

The technical result of the invention is the obtaining of nanostructured ceramic material on the basis of HA-TCP medium p is smarami particles is not more than 100 nm, fusible to a dense state (open porosity of less than 4%) at temperatures up to 700°C.

To achieve a technical result of the proposed calcium phosphate ceramics on the basis of a system of HA-TCP 80-99,5 wt.% and supplements of 0.5-20 wt.%. The additive has the following composition, wt.%: potassium carbonate and 80%lithium carbonate up to 80% and the calcium carbonate up to 60%. The ceramic material of the composition is unknown.

When firing additive (a mixture of carbonates of potassium, lithium and calcium) dissociates with the formation of cations and carbonation, when interacting with a lattice of sintered material formed numerous defects, both the anion and the cation, which promotes sintering by solid phase mechanism at lower temperatures. In addition, the sintering being on liquid-phase mechanism, because the mixture of salts, potassium carbonate, sodium and calcium forms a low-temperature melts, which also reduces the sintering temperature of the material. With the introduction of additives in amounts of less than 0.5 wt.% the material was characterized by high porosity and toast to a dense state above 700-750°C. the use of additives is higher than 20 wt.% the pottery was deformed. Introduction in addition to the carbonates of potassium, more than 80 wt.%, lithium more than 80 wt.% and calcium more than 60 wt.% leads to increasing sintering temperature over 700°C and growth of poristost is more than 5%.

Example. 1 Powder-based systems HA-TKF with an atomic ratio of CA/P, equal 1,66-1,68, with a specific surface area of 120 m2/g is mixed with the additive in an amount of 7 wt.% composition: carbonate potassium - 40 wt.%, lithium carbonate 40 wt.% and calcium carbonate 20 wt.%. Then the powder mixture is molded in the form of beams of size 50×6×6. Molded samples calcined at 640°C. the result is 100% HA ceramic samples with a porosity of not more than 1% and with an average particle size of about 60 nm.

Example 2. The blood samples were obtained analogously to example 1. Difference is the use of powder-based systems HA-TKF with an atomic ratio of CA/P, equal 1,49-1,51, with a specific surface area of 130 m2/g and an additive in the amount of 0.5 wt.%, this Supplement consists of lithium carbonate 20 wt.% and potassium carbonate 80 wt.%. Sintering was carried out at 680°C. the result is 100% TKF ceramic samples with a porosity of not more than 4% and an average particle size of about 70 nm.

Example 3. The blood samples were obtained analogously to example 1. The difference is the use of a powder system HA-TKF with calculated atomic ratio CA/P, equal 1,52-1,54, and a specific surface area of 115 m /g and an additive in an amount of 10 wt.%, this Supplement consists of lithium carbonate 80 wt.% and calcium carbonate 20 wt.%. Sintering was carried out at 650°C. the result is a ceramic samples. containing 76-80 wt.%TKF and 20-24 wt.% HA with a porosity of not more than 3% and with an average particle size of about 90 nm.

Were produced samples of ceramics having compositions within the stated and defined their properties in comparison with the prototype. The results obtained are summarized in table.

Nanostructured calcium phosphate-based material system tricalcium phosphate-hydroxyapatite for reconstruction of bone defects, wherein the tricalcium phosphate-hydroxyapatite ceramics includes the additional additive is potassium carbonate and/or lithium carbonate and/or calcium carbonate with the following ratio of components in ceramics, wt.%:

Hydroxyapatite and/or tricalcium phosphate80-99,5
additive0,5-20

in the following ratio of components in the additive, wt.%:
Cabinet potassium and/or lithiumup to 80
lithium carbonateup to 80
calcium carbonate60



 

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