DD244744A5 - Particles of biologically active glass and their method of preparation - Google Patents

Abstract

The invention relates to particles of biologically active glass and their method of production, which are used in the chemical industry. The invention provides particles of biologically active glass and their production processes which are suitable for the production of implantable and non-inflammatory implants. The object of the invention is to provide a method for producing particles of biologically active glass and the particles obtained by the method available. According to the invention, the particles are prepared from biologically active glass by spray-drying the aqueous acid solution of the biologically active glass precursors, heating the particles at elevated temperature to turn the glass precursor into glass.

Description

9. Particles of biologically active glass according to item 8, characterized in that the aqueous acid solution contains precursors selected from the group consisting of:

(a) Na ₂ O (SiO ₂ ) 3.38, Na ₂ SiO ₃ , (NaO) ₂ Si (CH ₃ I ₂ , silica and colloidal SiO ₂ ;

(b) Ca salts of the C 1 -C ₄ -alkanoic acid and Ca (NO ₃ I ₂ ;

(c) Na ₃ PO ₄ , Na ₂ HPO ₄ , NaH ₂ PO ₄ , Na ₂ H ₂ P ₂ O ₇ , Na ₃ PO ₃ , Na ₂ HPO ₃ , H ₃ PO ₄ , (NH ₄ J ₃ PO ₄ , (NH ₄ I ₂ HPO ₄ , (NH ₄ ) H ₂ PO ₄ , (NH ₄ I ₂ H ₂ P ₂ O ₇ , (NH ₄ J ₃ PO ₃ , (NH ₄ I ₂ HPO ₄

and (NH ₄ ) H ₂ PO ₃ , (NH ₄ I ₃ PO ₃ , (NH ₄ I ₂ HPO ₃ and (NH ₄ ) H ₂ PO ₃ ;

(d) Na ₂ B ₄ O ₇ and other sodium borates;

(e) sodium salts of C ₁ -C ₄ alkanoic acids and NaNO ₃ .

10. Particles of biologically active glass according to item 9, characterized in that the aqueous acid solution includes precursors selected from the group consisting of:

a) Na ₂ O (SiO ₂ 1 ₃ , ₃₈ ;

b) Ca (O ₂ CH) ₂ ,

c) Na ₃ PO ₄ -12H ₂ O,

d) NaO ₂ CH and

e) Na ₂ B ₄ O ₇ -IOH ₂ O.

Field of application of the invention

The invention relates to particles of biologically active glass and their method of preparation, which are applicable in the chemical industry.

Characteristic of the known technical solutions

As described by Hensch in a review article entitled "Biomaterials" in Science 208, 826-831 (1980), in the United States, 2-3 million artificial or prosthetic parts are implanted annually into individuals made of a wide variety of materials For example, devices are useful in the eye, ear and nervous system, heart, limbs, bladder and blood vessels, as well as for the repair or replacement of bones, ligaments and teeth, in these applications they fight both the degenerative effects of Aging as well as accidents resulting from accidents.

A summary of the state of biomaterials and their associated problems has been reported by Hall, in J. Biomed.

Mater. Res. Symposium, No. 2 (Part 1), pages 1 to 4 (1971) The article emphasizes the importance of the interface between an implant and the body tissue of the host.

U.S. Patent No. 4,171,544 discloses numerous biologically active glass compositions.

U.S. Patent 4,103,002 discloses a method of coating the surface of an alumina ceramic with a biologically active glass. The patent states that the surfaces of alumina ceramics are biologically inactive and bone tissue does not join or grow on them.

U.S. Patent 4,159,358 discloses a method of bonding a biologically active glass to a metal surface. In discussing the use of biologically active glasses as biomaterials, the patent states that it is impossible to construct from them sufficiently strong orthopedic or dental devices.

Object of the invention

The aim of the invention is the provision of particles of biologically active glass and their production processes, which are suitable for the production of biocompatible and no inflammation-inducing implants.

Explanation of the essence of the invention

The object of the invention is to provide a process for producing particles of biologically active glass and the particles obtained by the process.

The invention relates to a process for the preparation of particles of biologically active glass, characterized in that the aqueous acid solution of the precursors for the biologically active glass is dried by spray, the particles at elevated

Temperature to heat the glass precursor into glass, the aqueous acid solution having precursors,

to provide biologically active glass with the following composition:

SiO ₂ , From 40 to 62% by weight, Na ₂ O, 10bis32Gew .-%, CaO, 10bis32Gew .-%, CaF ₂ , 0.01 to 18% by weight, P ₂ O ₅ , 0.1 to 12% by weight, B ₂ O ₃ , 0,01bis20Gew .-%,

wherein the sum of Na ₂ O and CaO is at least 30% by weight.

A preferred embodiment of the process according to the invention consists in that the aqueous acid solution comprises at least one precursor, which in each case corresponds to one component of the biologically active glass, comprising:

SiO ₂ . ungefähr40Gew .-%,

Na ₂ O about 24.5 wt%,

CaO about 24.5% by weight,

P ₂ O ₅ about 6% by weight,

B ₂ O ₃ about 5% by weight.

Another preferred embodiment of the method according to the invention represents the pH of the aqueous acid solution which is less than 3.8.

Another preferred embodiment of the process according to the invention is characterized in that the aqueous acid solution comprises precursors selected from the group consisting of:

(a) Na ₂ O (SiO ₂ ) 3.38, Na ₂ SiO ₃ , (NaO) ₂ Si (CH ₃ J ₂ , silica and colloidal SiO ₂ ;

(b) Ca salts of C ₁ -C 10 alkanoic acids and Ca (NO ₃ I ₂ ;

(c) Na ₃ PO ₄ , Na ₂ HPO ₄ , NaH ₂ PO ₄ , Na ₂ H ₂ P ₂ O ₇ , Na ₃ PO ₃ , Na ₂ HPO ₃ , H ₃ PO ₄ , (NH ₄ J ₃ PO ₄ , (NH ₄ I ₂ HPO ₄ , (NH ₄ ) H ₂ PO ₄ , (NH ₄ I ₂ H ₂ P ₂ O ₇ , (NH ₄ I ₃ PO ₃ , (NH ₄ J ₂ HPO ₃ and (NH ₄ ) H ₂ PO ₃ ;

(d) Na ₂ B ₄ O ₇ and other sodium borates;

(e) sodium salts of C ₁ -C ₄ alkanoic acids and NaNO ₃ .

Yet another embodiment of the process is characterized in that the aqueous acid solution includes precursors selected from the group consisting of:

(a) Na ₂ O (SiO ₂ ) ₃ , ₃₈ ,

(b) Ca (O ₂ CH ₂ ) ₂ ,

(c) Na ₃ PO ₄ - 12H ₂ O,

(d) NaO ₂ CH, and

(e) Na ₂ B ₄ O ₇ -IOH ₂ O.

The invention further provides the particles of biologically active glass, which are characterized in that they are produced by the method according to the invention.

According to the invention, an aqueous acid solution composition of biologically active glass precursors is provided. The aqueous acid solution comprises a combination of all the precursors required for the recovery of a final product when the precursor composition is dried and fired.

The present invention is not limited to any particular precursors for any particular biologically active glass. Any combination of precursors that form biologically active glass particles can be used.

The term "biologically active glass" means that the glass is capable of forming in vivo bonds with bone, muscle or other body tissues For brevity, the term "glass" is used herein to mean biologically active glass. The term "aqueous solution" means an aqueous acid solution, suspension or dispersion of glass precursors.

The present invention also relates to compositions of glass precursor coated carrier particles and carrier particles coated with the glass formed by calcining the glass precursors. The present invention also relates to spherical particles of biologically active glass prepared by spray-drying the glass precursors and firing the spray-dried particles. Also included within the scope of the present invention are processes for preparing the solution compositions of the glass precursors, coating the carrier particles, drying and firing the precursor coated particles to form the glass-coated / fused carrier particles, and Spray-drying the solution composition of the glass precursors. The spherical particles are characterized by their generally spherical geometry and relatively smooth surfaces. Glass particles of the present invention are readily distinguishable from the prior art rough-edged, substantially non-spherical particles by microscopic examination.

The following patents disclose a number of biologically active glasses that can be prepared by the process of the present invention: U.S. Patent 4,159,358, U.S. Patent 4,103,002 and U.S. Patent 4,171,544. In general, the present invention includes all glasses whose components are incorporated herein by reference Form of a stable aqueous solution can be produced. Here, by "stable" is meant that during a period of one hour no significant precipitation occurs.

A typical range of compositions for a subset of the glasses contemplated to be in accordance with the practices of glass chemistry in the form of the oxides and fluorides is the

the following:

component Wt .-% SiO ₂ 40 to 62 Na ₂ O 10 to 32 CaO 10 to 32 CaF ₂ O to 18 P ₂ O ₆ 0.1 to 12 B ₂ O ₃ O to 20,

wherein the sum of Na ₂ O + CaO is at least about 30% by weight. Of the listed components, CaF _{2 is} not water-soluble. Accordingly, an aqueous solution of glass precursors containing CaF ₂ as an ingredient is treated so that the CaF _{2 is} suspended. One treatment method involves the addition of a solution of fluoride ions (via NaF or NH ₄ F) to a solution of Ca ⁺⁺ ions with vigorous stirring. Preferred glasses of this type contain about 0.5 to 6 wt% P ₂ O ₅ .

Another subset of the glasses contemplated includes those containing boron. A typical boron-containing glass contains 40 wt% SiO ₂ , 5 wt% B ₂ O ₃ , 6 wt% P ₂ O ₅ , 24.5 wt% CaO, and 24.5 wt% Na ₂ O.

Among the materials which may be used as supports for the glass are refractory mineral oxides, ceramics and the like. In fact, any material may be used that does not adversely interfere with the glass, glass precursors or body parts with which the material in question may come into contact. It stands . however, it is beyond question that the material in question is relatively tough and stable at the higher temperatures used to fire the glass.

Suitable materials include alumina, silica, carbon, silica-alumina, titania, clays, calcium silicate, feldspar, zinc oxide and the like, including any metals that the body contains. Preferred supports are alumina, silica, titania, and their mixtures and compositions. The size and concentration of the carrier particles will vary with the particular device to be made, their intended use, and the desired composition of the particles. Applicable particles have a diameter in the range up to 1 mm or more.

A sodium and silica-containing compound such as Na ₂ O · (SiO ₂ J ₃ ^ or Na ₂ SiO ₂ or (NaO) ₂ Si (CH ₂ ) ₂ may be used as a precursor for SiO ₂ and Na ₂ O. Other SiO ₂ precursors include silicic acid and colloidal SiO _2. The precursors for CaO include the calcium salts of ci to C ₄ alkanoic acids, preferably calcium formate Ca (O ₂ CH) ₂ , and, if HNO 3 is used for pH control, Ca (NO ₃ J _2. Precursors for P ₂ Os and Na ₂ O are the sodium phosphates Na ₃ PO ₄ , Na ₂ HPO ₄ , NaH ₂ PO ₄ , Na ₂ H ₂ P ₂ O ₇ and the sodium phosphites Na ₃ PO ₃ , Na ₂ HPO ₃ , NaH ₂ PO _3. The sodium phosphate is preferably Na ₃ PO ₄ .12H ₂ O. Other precursors for P ₂ O ₅ include H ₃ PO ₄ and the ammonium salt equivalents to the abovementioned sodium salts ₂ O ₃ include the sodium borates, which also provide Na ₂ O. Preference is given to Na ₂ B ₄ O ₇ · 10 H ₂ O. Precursors for Na ₂ O include the above-mentioned sodium salts and the sodium salts of Cr to C ₄ -alkanoic acids, preferably sodium formate and, if HNO _{3 is used} for pH control, NaNO ₃ . The introduction of such ions as SO ₄ " ² and Al ⁺³ , which would precipitate directly with other ions present, should be avoided.

Other ions that enhance biological growth can also be introduced into the solution. These ions include Mg ⁺² ; cf. Jaffe, "Metabolism Degenerative and Inflammatory Diseases of Bones and Joints," Lea and Febiger, Phila (1972), pp. 124ff., If K ₂ Oa I component of the glass is desired, it can be incorporated into the precursor solution as KHCO ₃ , KNO ₃ or KOC (O) R are introduced.

The aqueous solution compositions according to the present invention have a pH which is typically below about 5. Preferred acids for pH control are those which cleanly decompose on heating and leave no carbon residue which would require prolonged combustion. Such clean decomposition is a general requirement for an acid whose salts are used or which is used in free form. A sufficient amount of the acid is added to the solution to achieve the desired pH. Acids that meet the conditions of relatively high volatility and clean decomposition include nitric acid and the C ₁ to C ₄ alkanoic acids, including any acids whose calcium and sodium salts are used in the preparation of the solution or dispersion , Since these salts are preferably the formates, the most preferred acid is formic acid. For formic acid and nitric acid, the pH is at most about 3.8, and preferably about 3.3 to 3.8. For acetic acid, propionic acid and the butyric acids, the pH is at most about 4.6 and preferably about 4.1 to 4.6. The optimum pH for any particular precursor glass composition is easily determined by a simple experiment.

In the practical implementation of the coating operation, the particulate carrier to be coated is intimately mixed with a freshly prepared solution of the glass precursors with stirring and preferably with gentle grinding. In the laboratory, mixing, stirring and grinding are conveniently carried out in a mortar by means of a pestle. The wet solid may then be dried in air to remove all or part of the water, with spray-drying operations being preferred. The dried solid is then heated to a temperature high enough to remove any remaining water, to volatilize and / or decompose any residual formic acid, and to convert the component of the coating medium into the desired glass. This temperature is usually about 600 ⁰ C to about 1 550 ° C, although occasionally can effectively be employed somewhat lower temperatures. To minimize the risk of precipitate formation, a convenient method of preparing the coating solution is to employ two solutions, the first containing calcium formate and sodium formate, if used, and the second sodium silicate and, if one or more of the following are used, sodium phosphates and / or or sodium borate. Then formic acid is dissolved in both solutions, and the two solutions are mixed together with good stirring. The amount of formic acid to be used can easily be determined by simple experiments with aliquots of the two solutions.

The relative amount of each inorganic precursor dissolved in the coating medium is equivalent to the relative amount of the corresponding inorganic component needed to form the desired glass. Usually, the concentration of the precursors in the solution is about 100 g / l to 200 g / l. At lower concentrations, an unnecessarily large amount of water must be evaporated in the heating step. At higher concentrations, precipitation tends to increase. The carrier particles contacted with said precursors vary in size and concentration depending on the weight and / or volume ratio desired in the glass-coated carrier product. Multiple steps of coating / drying / sintering may also be performed. The biologically active glasses made using the process of the present invention using the precursor solution are well established and well accepted as components in biomedical products, including devices, prostheses, replacement parts and implants for the body. The usefulness of the supported biologically active glass of the present invention is at least as good as that of unsupported biologically active glass. In addition, the carrier-assisted glass has Vortejle in terms of strength /

Smoothness / stiffness and density - complemented by the hallmark of a homogeneous composition - which was previously impossible to achieve.

Coated carriers can be sintered and / or fused onto virtually any compatible substrate, thereby forming small or large devices of almost any geometric shape. The coated supports can also be molded or cast, thereby forming biomedical devices consisting solely of the support and glass described herein in a uniform, homogeneous and biocompatible matrix. The conditions which fulfill biomedical materials prepared from the carrier assisted glass according to the present invention are as follows:

(1) Their characteristics approach those of the body part they replace or are involved in;

(2) they are accepted by the living host without adverse reactions such as inflammation or toxicity;

(3) they form in vivo bonds with the host tissues and

(4) their implantation does not cause the formation of more than a relatively thin "capsule" at its interface with the body part of the host.

embodiment

The invention is explained in more detail below with reference to some examples.

example 1

Two solutions were prepared as follows: Solution I contained 56.9 g of calcium formate, 6.1 g of sodium formate and enough water for 500 ml of solution; herpH was 6.6. Solution II contained 32.0 g of Na ₃ PO ₄ .12H ₂ O, 158.5 g of Na ₂ O. (SiO ₂ ) ₃ , 38 in the form of an aqueous 37.1 percent solution and sufficient water for 500 mL of solution; her pH was 10.9.

To 37.5 ml of solution I was added 5.3 ml of formic acid, and the resulting solution was added rapidly to 37.5 ml of solution II with good stirring. The combined solution was added slowly to 155g of alumina in a mortar while the mixture was stirred with a pestle. The alumina was obtained by calcining Al ₂ O 3 .3H ₂ O (Alcoa C30BF). Stirring was continued until the mixture was uniform. The product was burned overnight in a muffle furnace at 1200 ⁰ C. The solid was again subjected to a surface treatment by the method described in this section, whereby a biologically active glass-coated alumina having a specific surface area of 35.6 m ² / g was obtained. The product contained 48.1% Al, corresponding to a total glassy alumina composition of about 9/91.

Example 2

Alumina was coated with biologically active glass essentially according to the procedure of Example 1, but with the following modifications: The alumina was calcined "Alcoa" C 333 BAl ₂ O ₃ .3H ₂ O, the amounts were 600g alumina, 180ml solution 1.180ml Solution II and 25.2 ml of formic acid, after mixing with the liquid, the treated alumina was air dried overnight and then fired at 1200 ° C for 1 hour.

Loose aggregates were crushed in a blender jar to yield a particulate glass-coated alumina having a specific surface area of 7.4 m ² / g. A representative sample was fractionated through sieves of increasing fineness and gave the following distribution of particle size:

on screen 0,177mm (80mesh) 2%,

through sieve 0,177 mm (80 mesh),

on screen 0.074 mm (200 mesh) 13%

through sieve 0,074mm (200mesh),

on screen 0.044 mm (325 mesh) 45%, and

through mesh 0.044 mm (325 mesh) 35%.

Example 3

An aqueous solution of a biologically active glass having the following composition was prepared without formation of a precipitate: 40% SiO ₂ , 5% B ₂ O ₃ , 6% P ₂ O ₆ , 24.5% CaO, and 24.5% Na ₂ O The two precursor solutions contained the following reagents:

Solution):

2.4 g NaO ₂ CH 56.9 g Ca (O ₂ CH) ₂ final volume: 600 ml (water).

Solution II:

140.7 g of 37.1% solution of Na ₂ O 3.38SiO ₂

13.6 g Na ₂ B ₄ O ₇ -10H ₂ O

32, IgNa ₃ PO ₄ - 12H ₂ O Final volume: 600 ml (water).

The mixing of solutions I and II was carried out as follows. Formic acid (0.5 ml) was added to the solution II with 5 ml of water. Then 5ml were added quickly with stirring. This gave a clear solution that did not gel within three days at room temperature.

The powdered alumina was coated as follows: First, Al ₂ O ₃ · 3H ₂ O (gibbsite), Alcoa C-331 was calcined with the following size grading at 400 ⁰ C:

94 to 99% less than 30μιη, 85 to 93% less than 20fim, 56 to 67% less than 10μηη and 20 to 40% less than 5μιη.

The alumina (100 g) was then ground with a solution of biologically active glass prepared from 25 ml of solution I, 3 ml of formic acid and 25 ml of solution II. The damp solid was dried in air and then baked 30 minutes in a platinum dish at 1200 ⁰ C, after which 102g of a free-flowing solid was obtained. This powder (75 g) was re-treated using 15 ml of the solution of 1.1.8 ml of formic acid and 15 ml of solution II. The final product was a white powder (80g). This powder raises the pH to about 10 in water.

Example 4

Two solutions were prepared as follows:

(I) 237.6g calcium formate, 114.4g sodium formate and

enough distilled water for 4 liters of solution;

(II) 158.4 g of Na ₄ P ₂ O ₇ -10H ₂ O,

1 448.8 g of 37.1% Na ₂ O -3.38 SiO ₂ and _

enough water for 4L solution.

To 720 ml of solution I containing 160 ml of formic acid was added 720 ml of solution II in a blender jar. This final solution was spray dried to a fine white powder. -

The powder contained water and formates, which were removed as follows: A 1-liter, three-necked flask equipped with a paddle stirrer, thermocouple and slow nitrogen purge was charged with 25 g of the powder with stirring and heating. The particles developed at 350 ° C to 400 ⁰ C vigorous gas. Additional powder was added, with the hot powder serving as a diluent. As the drying progressed, the powder addition was faster. The final product (214g 409,6g of spray-dried powder) was heated in a muffle furnace at 800 ⁰ C, and then ground to a powder. After further heating at 92o ⁰ C the dark gray product was a porous, easily zerstoßbarer glass foam of a composition comprising the 53,0Gew .-% SiO _2, 12,8Gew .-% CaO, 23,0Gew .-% Na ₂ O and 6 , 3Gew .-% P ₂ O _{5 of} the US-PS 4171 544 corresponded.

Example 5

This example was performed in a similar manner to Example 4.

Solution I:

2.4 g sodium formate, 56.9 g calcium formate, enough water for 600 ml.

Solution II:

140.7 g of 37.1% Na ₂ O 3.38SiO ₂ in water, 13.6 g of Na ₂ B ₄ O ₇ 10H ₂ O,

.32, IgNa ₃ PO ₄ - 12H ₂ O, "

enough water for 600 ml. '

To prepare the solution for spray drying, 720 ml of solution I and 100.8 ml of formic acid were filled in a blender jar and vigorously stirred while 720 ml of solution II were added. The solution was then spray-dried as described in Example 4 and heated and stirred. After the temperature was increased to 1050 ⁰ C, the resulting product was a krümeligerweißer solid which was easily crushed to a white powder in Mörsermitdem pestle. Based on the amounts of the materials used, this product had the following composition by weight: 23.7% Na ₂ O, 24.8% CaO, 6.0% P ₂ O ₅ , 40.5% SiO ₂ and 5 , 0% B ₂ O ₃ .

Example 6

Calcined Al ₂ O ₃ .3H ₂ O (Alcoa C 30 BF) was coated with glass. The distribution of particle sizes was as follows:

80 to 84% pass through sieve # 325, i. less than 45 ^ m;

97 to 99% pass through sieve # 200, d. H. less than 75μηι.

Two solutions were prepared as follows: Solution I contained 56.9 g of calcium formate, 6.1 g of sodium formate and enough water for 500 ml of solution; herpH was 6.6. Solution II contained 32.0 g Na ₃ PO ₄ 12H ₂ 0.158.5 g Na ₂ O. (SiO ₂ I ₃₁₃₈ In the form of an aqueous 37.1% solution and enough water for 500 ml solution, its pH was 10.9.

To 50 ml of solution I was added 7 ml of formic acid and the resulting solution was added rapidly to 50 ml of solution II with good stirring. The combined solution was added slowly to 200 g of alumina in a mortar while the mixture was stirred with a pestle. Stirring was continued until the mixture was uniform. The product was fired overnight in a muffle furnace at 1200 ^° C. The solid was again subjected to surface treatment by the method described in this section, after which a glass-coated alumina was obtained.

Example 7

A spray-dried biologically active glass powder was prepared

Solution I:

68.3g calcium formate, 7.3g sodium formate, enough water for 600ml solution

Solution II:

190.2 g 37.1% Na ₂ O 3.38SiO ₂ , 38.5 g Na ₃ PO ₄ -12H ₂ O, enough water for 600 ml solution.

Further solutions were made until 41 of each solution had been prepared.

720 ml of solution II were added to 720 ml of solution I and 10 ml of formic acid in a blender jar with vigorous stirring. This final solution was then spray dried.

A three-neck round bottom flask was equipped with a paddle stirrer and N ₂ inlet tube and heated with a Meeker burner. About 25 g of the spray-dried powder was placed in the nitrogen-purged flask, the stirrer was started, and the burner was turned on. The powder stuck together as liquid began to distill from the flask. Upon continued heating, the particles became free-flowing and vigorously developed a combustible gas at 380 ^° C, probably CO and H ₂ . Further spray-dried material was added at such a rate that no agglomeration occurred. In the course of 35 minutes, 320 g of spray-dried material were added. The stirred solid was heated to 520 ⁰ C and cooled. The experiment required 45 min and provided 210 g of a brown free-flowing powder. When heated to 950 ^° C in the air, the product became a white crumbly cake which easily pounded into a powder in a mortar and pestle.

Example 8

This example represents a process for producing biologically active glass and / or glass-coated carrier particles using only a single solution.

In 15 ml H ₂ O 1.6 g Na ₂ PO ₄ · 12H ₂ O were dissolved. To this solution was added 7.9 g of a 37.1% aqueous solution of Na ₂ O 3.38SiO ₂ . With water was made up to a volume of 25 ml, and 5 ml of formic acid were added, whereupon a clear solution was obtained. Thereafter, 2.8 g of Ca (O ₂ CH) ₂ and 0.3 g of NaO ₂ CH were added with vigorous stirring. The solution mentioned did not gel for one hour. Upon drying and firing, this precursor solution provides a biologically active glass with the composition

SiO ₂ : 45%, Na ₂ O: 24.5%, CaO: 24.5%, P ₂ O ₅ : 6%.

The precursor solution may be spray dried and then fired to form globular, biologically active glass particles. Alternatively, carrier particles of alumina, silica, carbon, silica-alumina minerals, titania, clay, calcium silicate, feldspar, and zinc oxide, alone or in any combination, may be added to the solution with good agitation. Subsequent drying provides glass precursor coated carrier particles which can be molded and calcined in the dry state to form shaped biomedical devices. In another alternative, the glass precursor coated carrier particles can be treated with an adhesive containing one or more individual components of biologically active glass, and the applied adhesive mass can be shaped and fired.

Example 9

This example generally demonstrates how to incorporate certain additives into a solution of biologically active glass precursors. For example, Sr, Ba, Li, Al, Fe and / or Ti components can be introduced into an already prepared aqueous nitric acid solution of the precursors. Alternatively, the glass precursors and additive precursors may be formulated in one step into a modified solution of biologically active glass precursors. The additional components are in the nitric acid solution in the form of their nitrates, z. B. as Sr (NO ₃ J ₂ , Ba (NO ₃ I ₂ , LiNO ₃ , Al (NO ₃ I ₃ , Fe (NO ₃ J ₃ or alsTitanyl-ionTiO ⁺⁺ . In each case make sure that because Explosion hazard Formic acid / Formates should not be mixed with nitric acid / nitrates.

Example 10

Cylindrical a-alumina pellets with a diameter of 1.27 cm (V2inch) and einerHöhevon 1.27 ⁽¹ / 2inch) were washed, dried and treated with the combined aqueous solution of Example 1, dried in the air at 1200 ⁰ C burned.

The coating, drying and firing operations were repeated once and the surfaces were examined by scanning electron microscopy. The fine holes and cracks on the original alumina surface were filled. The surface was smooth and without cracks and scratches.

Claims (8)

Invention claim: A process for the production of particles of biologically active glass, characterized in that the aqueous acid solution of the precursors for the biologically active glass is dried by spray, the resulting spray-dried particles are heated at elevated temperature to the glass precursor in Glass, wherein the aqueous acid solution has precursors to provide biologically active glass having the following composition: SiO ₂ , 40 to 62% by weight, Na ₂ O, 10 to 32% by weight, CaO, 10 to 32% by weight, CaF ₂ , 0.01 to 18% by weight, P ₂ O ₅ , 0.1 to 12% by weight and B ₂ O ₃ , 0.01 to 20% by weight, wherein the sum of Na ₂ O and CaO is at least 30% by weight. 2. The method according to item!, Characterized in that the aqueous acid solution contains at least one precursor, which corresponds in each case to a component of the biologically active glass, comprising: SiO ₂ about 40% by weight, Na ₂ O about 24.5% by weight, CaO about 24.5% by weight, P ₂ O ₅ about 6 wt .-% and B ₂ O ₃ about 5 wt .-%. 3. The method according to item 2, characterized in that the aqueous acid solution has a pH which is below 3.8. 4. The method of item 3, characterized in that the aqueous acid solution includes precursors selected from the group consisting of: (a) Na ₂ O (SiO ₂ ^ ₃₈ , Na ₂ SiO ₃ , (NaO) ₂ Si (CH ₃ I ₂ , silica and colloidal SiO ₂ ; (b) Ca salts of C ₁ -C ₄ alkanoic acids and Ca (NO ₃ I ₂ ; (c) Na ₃ PO ₄ , Na ₂ HPO ₄ , NaH ₂ PO ₄ , Na ₂ H ₂ P ₂ O ₇ , Na ₃ PO ₃ ,
Na ₂ HPO ₃ , H ₃ PO ₄ , (NH ₄ J ₃ PO ₄ , (NH ₄ I ₂ HPO ₄ , (NH ₄ ) H ₂ PO ₄ ,
(NH ₂ H ₂ P ₂ O ₇ , (NH ₄ ) ₃ PO ₃ , (NH ₄ J ₂ HPO ₃ and (NH ₄ ) H ₂ PO ₃ ; (d) Na ₂ B ₄ O ₇ and other sodium borates; (e) sodium salts of C ₁ -C ₄ alkanoic acids and NaNO ₃ . 5. The method according to item 4, characterized in that the aqueous acid solution includes precursors selected from a group consisting of: (a) Na ₂ O (SiO ₂ ) ₃ , ₃₈ , (b) Ca (O ₂ CH ₂ J ₂ , (c) Na ₃ PO ₄ - 12H ₂ O, (d) NaO ₂ CH, and ' (e) Na ₂ B ₄ O ₇ -IOH ₂ O. Particles of biologically active glass, characterized in that they are prepared by spray-drying the aqueous acid solution of the precursors for the biologically active glass, heating the resulting spray-dried particles at elevated temperature to add the glass precursor into glass wherein the aqueous acid solution has precursors to provide biologically active glass having the following composition: SiO ₂ , 40 to 62% by weight, Na ₂ O, 10 to 32% by weight, CaO, 10 to 32% by weight, CaF ₂ , 0.01 to 18% by weight, P ₂ O ₅ , 0.1 to 12% by weight, B ₂ O ₃ , 0.01 to 20% by weight, wherein the sum of Na ₂ O and CaO is at least 30% by weight. 7. The biologically active glass particle according to item 6, characterized in that the aqueous acid solution includes at least one precursor, each corresponding to a component of the biologically active glass, comprising: SiO ₂ about 40% by weight, Na ₂ O about 24.5% by weight, CaO about 24.5% by weight, P ₂ O ₆ about 6 wt .-% and B ₂ O ₃ about 5 wt .-%. 8. particles of biologically active glass according to item 7, characterized in that the aqueous acid solution has a pH which is below 3.8.