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A two-step method was used to fabricate the hydroxyapatite (HAP)/silk fibroin (SF) scaffolds, i.e. the nano-sized HAP/SF composite powders were prepared by co-precipitation, which were then blended with SF solution to fabricate the HAP/SF composite scaffolds. The obtained scaffolds showed a 3D porous structure. The porosity was higher than 90% with the average macropore size of 214.2 µm. Moreover, the nano-sized HAP/SF composite powders were uniformly dispersed in the silk fibroin matrix, which provided the scaffolds enhanced compressive properties. The cell culture assay showed that the scaffolds fabricated by the two-step method could improve the cell proliferation and osteogenic differentiation when compared with those prepared by the conventional one-step blending method. The results suggested that the two-step method could promote the uniform dispersion of HAP in the SF matrix and efficient combination between the HAP and the matrix, which may provide a potential application in the composite scaffold preparation for tissue engineering. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Porous microspheres fabricated from bioceramics have great potential for cell delivery in injectable tissue engineering application. The size and structure of pores in the microspheres are important for the effective protection and transportation of cells. In this study, porous hydroxyapatite microspheres are fabricated through the water-in-oil emulsion method followed by a calcination treatment at the high temperature. Both self-made resorcinol-formaldehyde (RF) composite spheres and camphene are used as pore-forming agents to produce big pores corresponding to the size of RF spheres and connected channel among big pores in hydroxyapatite matrix. The properties of the microspheres are characterized using X-ray diffraction, thermogravimetry analysis, universal material machine, field emission scanning electron microscopy. Cell assays are carried out to evaluate the cellular compatibility of the microspheres. The results showed that the hydroxyapatite microspheres with controllable pore structure and high porosity could be fabricated by this method, which have better strength to resist the compressive force. The microspheres are conducive to support adhesion, proliferation and differentiation of MC3T3-E1 cells. The results indicate that the obtained porous hydroxyapatite microspheres can be a permeable microenvironment for cell delivery in injectable tissue engineering. [ABSTRACT FROM AUTHOR]

Despite superior clinical handling, excellent biocompatibility, biodegradation property of calcium phosphate needs to be improved to coincide with the rate of new bone formation. In this study, spherical CaCO 3 are fabricated in the presence of the silk sericin and then transformed into porous hydroxyapatite (HAP) microspheres via hydrothermal method. The degradation behavior of obtained CaCO 3 , HAP and their mixture is first investigated in vitro . The result demonstrates that the weight loss of HAP microspheres are almost 24.3% after immersing in pH 7.40 Tris-HCl buffer solution for 12 weeks, which is far slower than that of spherical CaCO 3 (97.5%). The degradation speed of the mixtures depends on the proportion of CaCO 3 and HAP. The mixture with higher content of CaCO 3 possesses a quicker degradation speed. The obtained CaCO 3 and HAP microspheres are injected into subcutaneous tissue of ICR mice with the assistance of sodium alginate. The result in vivo also shows an obvious difference of degradation speed between the obtained CaCO 3 and HAP microspheres, implying it is feasible to modulate the degradation property of the mixture through changing the proportion of CaCO 3 and HAP The good cytocompatibility of the two kinds of microspheres is proved and a mild inflammation response is observed only at early stage of implantation. The job offers a simple method to modify the degradation properties of biomaterial for potential use in bone tissue engineering. [ABSTRACT FROM AUTHOR]

To fabricate hard tissue implants with bone-like structure using a biomimetic mineralization method is drawing much more attentions in bone tissue engineering. The present work focuses in designing 3D silk fibroin hydrogel to modulate the nucleation and growth of hydroxyapatite crystals via a simple ion diffusion method. The study indicates that Ca 2+ incorporation within the hydrogel provides the nucleation sites for hydroxyapatite crystals and subsequently regulates their oriented growth. The mineralization process is regulated in a Ca 2+ concentration- and minerlization time-dependent way. Further, the compressive strength of the mineralized hydrogels is directly proportional with the mineral content in hydrogel. The orchestrated organic/inorganic composite supports well the viability and proliferation of human osteoblast cells; improved cyto-compatibility with increased mineral content. Together, the present investigation reports a simple and biomimetic process to fabricate 3D bone-like biomaterial with desired efficacy to repair bone defects. [ABSTRACT FROM AUTHOR]

Abstract: Hydroxyapatite-modified titanate nanowire scaffolds as alternative materials for tissue engineering have been developed via a titanate nanowire matrix assisted electrochemical deposition method. The macroporous titanate nanowire matrix on Ti metal was fabricated by a hydrothermal method, and then followed by an electrochemical synthesis of hydroxyapatite nanoparticles on titanate nanowire. The incorporation of titanate nanowire matrix with high oriented hydroxyapatite nanoparticles generates hierarchical scaffolds with highly osteogenic, structural integrity and excellent mechanical performance. As-prepared porous three dimensional interconnected hydroxyapatite-modified titanate nanowire scaffolds, mimicking the nature’s extracellular matrix, could provide a suitable microenvironment for tissue cell ingrowth and differentiation. The ceramic titanate nanowire core with HA nanoparticle sheath structure displays superhydrophilicity, which facilitates the cell attachment and proliferation, and induces the in vitro tissue-engineered bone. Human osteoblast-like MG63 cells were cultured on the hydroxyapatite-modified titanate nanowire scaffolds, and the results showed that the scaffolds highly promote the bioactivity, osteoconductivity and osteoblast differentiation. [Copyright &y& Elsevier]