Hydroxyapatite Fibers Research Articles

Hydroxyapatite fiber reinforced poly( α-hydroxy ester) foams for bone regeneration

A process has been developed to manufacture biodegradable composite foams of poly(DL-lactic-co-glycolic acid) (PLGA) and hydroxyapatite short fibers for use in bone regeneration. The processing technique allows the manufacture of three-dimensional foam scaffolds and involves the formation of a composite material consisting of a porogen material (either gelatin microspheres or salt particles) and hydroxyapatite short fibers embedded in a PLGA matrix. After the porogen is leached out, an open-cell composite foam remains which has a pore size and morphology defined by the porogen. By changing the weight fraction of the leachable component it was possible to produce composite foams with controlled porosities ranging from 0.47±0.02 to 0.85±0.01 ( n=3). Up to a polymer : fiber ratio of 7 : 6, short hydroxyapatite fibers served to reinforce low-porosity PLGA foams manufactured using gelatin microspheres as a porogen. Foams with a compressive yield strength up to 2.82±0.63 MPa ( n=3) and a porosity of 0.47±0.02 ( n=3) were manufactured using a polymer : fiber weight ratio of 7 : 6. In contrast, high-porosity composite foams (up to 0.81±0.02, n=3) suitable for cell seeding were not reinforced by the introduction of increasing quantities of hydroxyapatite short fibers. We were therefore able to manufacture high-porosity foams which may be seeded with cells but which have minimal compressive yield strength, or low porosity foams with enhanced osteoconductivity and compressive yield strength.

ChemInform Abstract: Novel Preparation Method of Hydroxyapatite Fibers.

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Novel Preparation Method of Hydroxyapatite Fibers

A novel method for preparing calcium hydroxyapatite (Ca10(PO4)6(OH)2: HAp) fibers has been developed. HAp fibers can be prepared successfully by heating a compact consisting of calcium metaphosphate (ß‐Ca(PO3)2) fibers with Ca(OH)2 particles in air at 1000°C and subsequently treating the resultant compact with dilute aqueous HCl solution. The ß‐Ca(PO3)2 fibers and the Ca(OH)2 in the compact were converted into fibrous HAp and CaO phases by the heating, and the CaO phase was removed by acid‐leaching. HAp fibers obtained in the present work were 40‐150 µm in length and 2‐10 µm in diameter. The fibers had almost the same dimensions as those of the ß‐Ca(PO3)2 fibers.

Poly(α-Hydroxy Ester)/Short Fiber Hydroxyapatite Composite Foams for Orthopedic Application

AbstractA process has been developed to manufacture biodegradable composite foams of poly(DL-lactic- co-glycolic acid) (PLGA) and hydroxyapatite short fibers for use in bone regeneration. The processing technique allows the manufacture of three-dimensional foam scaffolds and involves the formation of a composite material consisting of a porogen material (either gelatin microspheres or salt particles) and hydroxyapatite short fibers embedded in a PLGA matrix. After the porogen is leached out, an open-cell composite foam remains which has a pore size and morphology defined by the porogen. The foam porosity can be controlled by altering the volume fraction of porogen used to make the composite material. Foams made using NaCl particles as a porogen were manufactured with porosities as high as 0.84±0.01 (n=3). The short hydroxyapatite fibers served to reinforce the PLGA. The compressive yield strength of foams manufactured using gelatin microspheres as a porogen was found to increase with fiber content. Foams with compressive yield strengths up to 2.82±0.63 MPa (n=3) with porosities of 0.47±0.01 (n=3) were manufactured using 30% by weight hydroxyapatite fibers in the initial composite prior to leaching. These composite foams with improved mechanical properties may also be expected to have enhanced osteoconductivity and hence provide a novel material which may prove useful in the field of bone regeneration.

アルギン酸ナトリウムを用いた繊維状水酸アパタイトの合成

In this paper, fibrous hydroxyapatite (HAp), which is expected to be used as an implant material to periodontal bone defects, was prepared by using sodium alginate (Na-Alg.).The starting materials were prepared by dissolving Na4P2O7 into 5% Na-Alg. solution; Na-Alg./Na4P2O7 (weight ratio)=2.4, 2.6, 2.8, 3.0, 3.2, while the mixed solution of 0.15mol Ca(CH3COO)2 and 0.1mol CaCl2 was used as the spinning solution; pH=6.0, 6.5, 7.0, 7.5.The starting materials were spun through a nozzel of 0.1φmm into the spinning solution in a vessel of 16ml capacity. Gelatinous fibers obtained were aged, dried and calcined at 900°C for 1 hour. The thermal transformation of the calcined fibers and their compositions were examined by using X-ray diffraction, DTA, and chemical analysis. From these results, the optimum condition for preparing fibrous HAp was found to be as follows; Na-Alg./Na4P2O7=3.0, pH=6.5.In order to remove pores appearing during the heating process, the dried fibers formed under the optimum condition were heat-treated under reduced pressure (at 133Pa and 900°C for 3 hours). The resulting HAp fibers were about 30-40μm in diameter. It was also confirmed that the HAp phase in the fibers was maintained even after heat-treated at 1300°C for 1 hour in air.