RU2580633C1 - METHOD OF PRODUCING Sr-CONTAINING CARBONATE HYDROXYLAPATITE FROM STANDARDISED TEST SOLUTION OF HUMAN SYNOVIAL FLUID - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention refers to medicine, in particular - to method of producing Sr-containing carbonate hydroxylapatite from standardised test solution of human synovial fluid. Method of producing Sr-containing carbonate hydroxyl apatite involves production of inorganic substance; for this purpose a model medium with the following composition is prepared in made environment: CaCl₂ - 1.3431-0.8059 g/l, Na₂HPO₄·12H₂O - 7.4822 g/l, NaCl - 2.8798 g/l, MgCl₂·6H₂O - 0.4764 g/l, Na₂SO₄ - 1.6188 g/l, KCl - 0.3427 g/l, at concentration of ions Sr - 0+0.2686 g/l, followed by deposition with pH 7.4 during 7 days. Obtained sediment is filtered, dried at 100 °C during 4 hours.

EFFECT: invention implementation allows to produce Sr-containing carbonate hydroxyl apatite, which can then be used for targeted delivery of medicinal preparations.

1 cl, 5 tbl

Description

The invention relates to medicine and the creation of new biomedical materials that can be used to create biphasic composites based on Sr-containing carbonate hydroxylapatite, which can be used for targeted drug delivery.

A known method of producing carbonate hydroxylapatite, close to the inorganic matrix of bone tissue (patent RU 2526191 C1), from a model solution of human synovial fluid in which a solution of composition is prepared: CaCl ₂ - 1.3431 g / l, Na ₂ HPO ₄ · 12H ₂ O - 7.4822 g / l, NaCl - 2.8798 g / l, MgCl ₂ · 6H ₂ O - 0.4764 g / l, Na ₂ SO ₄ - 1.6188 g / l, KCl - 0.3427 g / l, deposition is carried out at a concentration of carbonate ions of 24 mmol / l, temperature 22-25 ° C, pH 7.4 + 0.05 for 30 days.

Closest to the technical nature of the claimed is a method for producing Sr-containing hydroxylapatite with various substitution of calcium ions for strontium ions (Capuccini C, Torricelli P, Boanini E, Gazzano M, Giardino R, Bigi A. Interaction of Sr-doped hydroxyapatite nanocrystals with osteoclast and osteoblast-like cells // J Biomed Mater Res A. 2009 Jun; 89 (3): 594-600). According to this method, the synthesis of crystals of Sr-containing hydroxylapatite was carried out in an inert atmosphere of N ₂ by adding dropwise 50 ml of 0.65 M (NH ₄ ) ₂ HPO ₄ solution to 50 ml of 1.08 M Ca (NO ₃ ) ₂ · 4H ₂ O at pH 10. The pH was adjusted with a solution of NH ₄ OH. The precipitate was kept in the reaction solution for 5 h at 90 ° C with constant stirring, then centrifuged at 10,000 rpm for 10 min and washed again with distilled water free of CO ₂ . The product was dried at 37 ° C overnight.

The method allows to obtain nanocrystals of Sr-containing hydroxylapatite with different strontium content in hydroxylapatite from 0-10% of the mass. The disadvantages of the method include the inability to obtain Sr-containing carbonate hydroxylapatite; at all stages of the synthesis, measures were taken to exclude carbonate ions from entering the structure of the resulting crystals.

The objective of the invention is to develop a method for producing Sr-containing carbonate hydroxylapatite from a model solution of human synovial fluid, which can be further used for targeted drug delivery.

The specified technical result is achieved by the fact that the proposed method for producing Sr-containing carbonate hydroxylapatite from a model solution of human synovial fluid, close to the inorganic matrix of the bone, including obtaining an inorganic substance, in an artificially created environment for this purpose, a model medium of the specified composition is prepared: CaCl ₂ - 1.3431-0 , 8059 g / l, Na ₂ HPO ₄ · 12H ₂ O - 7.4822 g / l, NaCl - 2,8798 g / l, MgCl ₂ · 6H ₂ O - 0.4764 g / l, Na ₂ SO ₄ - 1.6188 g / l , KCl - 0.3427 g / l, with an ion concentration of Sr - 0 ÷ 0.2686 g / l, precipitation is carried out at a pH of 7.4, for 7 days, gender the sediment is filtered, dried at a temperature of 100 ° C for 4 hours.

Synovial fluid is a biological medium that is unique in biophysical, physicochemical properties and composition and performs a number of functions in the joints: metabolic (exchange), barrier (protective), tread (biomechanical). The metabolic function of synovial fluid plays a large role in the treatment of patients with bone pathologies, playing the role of a carrier of various inorganic and organic ions that can be embedded in the structure of bone apatite and contribute to a change in its biophysical, structural and morphological features. So, recently, on the basis of experimental and clinical studies, evidence has been obtained that strontium compounds and preparations based on it stimulate the formation of bone tissue and inhibit its destruction.

The synthesis of Sr-containing carbonate hydroxylapatite was carried out from a model medium approximated in ion-electrolyte composition, pH, and ionic strength to human synovial fluid. Precipitation from solutions was carried out at a pH value of 7.4, which corresponds to the physiological value of the acidity of synovia normal [Luneva S.N. Biochemical changes in the tissues of the joints with degenerative-dystrophic diseases and methods of biological correction: Dis. ... Dr. Biol. sciences. Mound. 2003.297 s.]. In this case, the pH was adjusted to the required physiological values by adding 20% NaOH solution or concentrated HCl. These concentration ranges correspond to the content of ions in the synovial fluid of a person [Kirsanov A.I. The concentration of chemical elements in different biological environments of man. Clinical laboratory diagnostics. 2001. No3. S. 16-20] are presented in table. one.

For the preparation of model solutions used salts (CaCl _2, Na ₂ HPO ₄ · 12H ₂ O, MgCl ₂ · 6H ₂ O, NaHCO _3, Na ₂ SO _4, KCl, NaCl, SrCl ₂ · 6H ₂ O) brand BH a.h. and distilled water. Salts and their amount were selected so that the concentration of their ions in solution and ionic strength were as close as possible to these parameters of the simulated system, namely, the synovial fluid. To obtain Sr-containing materials based on carbonate hydroxylapatite, different contents of strontium and calcium were added to the model experiments, while their concentration varied in the range from 0 to 100 mass. % of the maximum possible concentration of calcium. The inorganic salt SrCl ₂ 6 · H ₂ O was used as sources of Sr ²⁺ ions. The solid phase was crystallized for 7 days at t = 22-25 ° C. The precipitate was dried at a temperature of ~ 100 ° C.

The analysis of the supernatant was carried out by chemical methods to establish the residual concentrations of calcium ions and phosphate ions in the filtrate. The Ca / P ratio was estimated by the difference between the initial and final ion concentrations in the system. Based on data on the contents of calcium and phosphorus in the solid phase, the Ca / P ratio was determined. With an increase in the strontium content in the initial solution, a regular decrease in the Ca / P coefficient is observed; the inconstancy of the stoichiometric ratio can be explained by possible isomorphic substitutions in the cationic sublattice.

According to the XRD results, the resulting materials contain hydroxylapatite and brushite. With an increase in the amount of strontium ions in the solid phase, an increase in the fraction of brushite and a decrease in the fraction of hydroxylapatite in the precipitate occur. In the table. Figure 2 shows the crystallite sizes of calcium phosphate with varying Sr concentrations for the samples, calculated according to powder diffractometry using the Selyakov-Scherrer formula.

In the table. Figure 3 shows the dependence of the specific surface on the concentration of strontium in the initial model solution. For the obtained samples, the specific surface areas of the HA powders were determined. In the concentration range from 0 to 50.0% of the mass. strontium detected a decrease in the specific surface of the particles. This may be due to the formation of brushite, which is consistent with the results of XRD.

640-550 см^-1, асимметричных валентных колебаний υ₃ Р-O в $$P{O}_{\text{4}}^{\text{3-}}$$

; 1060-1030 см^-1, деформационных колебаний О-С-O в $$C{O}_{\text{3}}^{\text{2-}}$$

870-879 см^-1.To determine the qualitative composition of the synthesized material, IR spectroscopy was used. All IR spectra of the powders are characterized by the presence of stretching vibration bands of OH groups in the wavelength range of 3570-3730 cm ^-1 and deformation vibrations at 3000-3600 cm ^{-1 of} O-H groups involved in the formation of hydrogen bonds. We can also note the bands of bending vibrations υ ₄ О-Р-O в $$P{O}_{\text{four}}^{\text{3-}}$$

640-550 cm ^-1 , asymmetric stretching vibrations υ ₃ Р-O в $$P{O}_{\text{four}}^{\text{3-}}$$

; 1060-1030 cm ^-1 , deformation vibrations O-C-O in $$C{O}_{\text{3}}^{\text{2-}}$$

870-879 cm ^-1 .

In the table. Figure 4 shows the dependence of Ca / P and mass on the concentrations of calcium and strontium. From the data table. 4 it is seen that at high concentrations of Sr in the initial solution (60-100 wt.%), Calcium phosphate prevails with a ratio of Ca / P≈0.5, with a content of 30-50 wt. % formed octacalcium phosphate (Ca ₈ (HPO ₄ ) ₂ (PO ₄ ) ₄ · 5H ₂ O with a ratio of Ca / P≈1.2, with a strontium content of 20-30 wt.% crystallized calcium-deficient hydroxylapatite (Ca ₉ (HPO ₄ ) (PO ₄ ) ₅ (OH)) with a Ca / P ratio of <1.67, and with minimal Sr contents, hydroxylapatite (Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ ) with a Ca / P ratio of 1.67 is formed Thus, the optimal range of concentration of strontium ions to obtain carbonate hydroxylapatite is 0 ÷ 0.2686, g / l (W _Sr , wt.% Up to 20%).

In addition, it was noted that with a decrease in calcium concentration and an increase in strontium, the mass of the formed solid phase decreases.

The strontium content was determined in the obtained solid phases by atomic emission analysis. In the table. 5 shows the Sr content in the resulting precipitates. The results of this analysis show that strontium is included in the composition of the obtained samples (Table 5).

In this case, the concentration of strontium in the sediments directly proportionally depends on the concentration of strontium-containing agents in the initial model mother liquor.

Thus, the claimed method allows under conditions simulating a synovial fluid, to obtain Sr-substituted carbonate hydroxylapatite, close to the inorganic matrix of bone.

Claims (1)

A method of producing Sr-containing carbonate hydroxylapatite from a model solution of human synovial fluid close to the inorganic matrix of bone, including the preparation of an inorganic substance, in an artificially created medium, a model medium of the indicated composition is prepared for this: CaCl ₂ - 1.3431 - 0, 8059 g / l, Na ₂ HPO ₄ · 12H ₂ O - 7.4822 g / l, NaCl - 2.8798 g / l, MgCl ₂ · 6H ₂ O - 0.4764 g / l, Na ₂ SO ₄ - 1.6188 g / l, KCl - 0.3427 g / l, when the concentration of ions Sr is 0 ÷ 0.2686 g / l, precipitation is carried out at a pH value of 7.4 for 7 days, the resulting precipitate is filtered, dried at a temperature of 100 ° C for 4 hours.