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A fibrous precursor for bone repair composites was made by coating poly(L‐lactide) (PLLA) fibers with hydroxyapatite (HA) using a biomimetic method. To enhance the bonding between the HA coating and the PLLA fiber, PLLA fibers were etched with either sodium hydroxide or sodium hypochlorite to generate carboxyl groups on fiber surfaces. The experiments were designed to determine the influence of etching on the fiber surface morphology and chemistry as well as the subsequent HA coating on the etched fiber surfaces. It was found that the etching pretreatment increased the roughness as well as the hydrophilicity of fibers, indicating that hydrolysis of PLLA chains had taken place on fiber surfaces. The etching pretreatment also promoted HA coating formation by introducing thicker coating on the surface of fibers with a longer etching time, a higher etching concentration, or with NaOCl as the etching agent. A mechanism of surface hydrolysis and oxidation of PLLA was proposed. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009 [ABSTRACT FROM AUTHOR]

Abstract: Human bone mineral contains calcium-deficient crystalline hydroxyapatite (HA) embedded in collagen fibers. Research over the past two decades has focused on preparing synthetic HA, which closely resembles bone apatite and exhibits excellent osteoconductivity. This paper describes the synthesis of nano-HA particles via a wet precipitation method. The concentration of the reactants (0.5, 1.0 and 2.0 g/dL) and the temperature of the reaction (25, 70 and 100 °C) were varied. FESEM images were used to determine the size and shape of the resulting nano-particles. The length and breadth of the HA particles were found to increase with the temperature, while the aspect ratio increased with both the concentration and the temperature. The average length of the particles was in the range 53–165 nm and the average breadth in the range 29–52 nm. Agglomerates of HA precipitates were formed during the synthesis process. HA precipitated at 25 °C and concentration 0.5 g/dL resulted in large agglomerates with a specific surface area of 79.8 m2/g. HA agglomerates synthesized at each condition were pressed into discs and sintered at 1200 °C. It was found that there was a positive correlation (p=0.015) between sintered density and biaxial flexural strength. A maximum strength of 57.4 MPa was observed for the specimens 2.0–70 which also attained the highest density, 92%. XRD results indicated that most of the sintered discs had slightly decomposed. The decomposition of the specimens and their resulting microstructures also contributed to the mechanical strength drop of the specimens. [Copyright &y& Elsevier]