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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: Plenty of techniques have been developed to modify the surface character of titanium (Ti) and its alloys in order to realize their biological bond to natural bone. In this work, a biomimetic process was employed to form a hydroxyapatite (HAp) coating on the alkali-heat treated Ti substrate in 1.5 times simulated body fluid (1.5×SBF) with the addition of a recombinant collagen-like protein. The coating was characterized using SEM-EDX, FESEM, and XRD. Results showed that the recombinant collagen-like protein could accelerate the preferential nucleation and directional growth along c axis of HAp on the pretreated Ti substrates. The investigation of in vitro cell cultivation showed that the existence of recombinant collagen-like protein in coating could improve the initial cell adhesion, proliferation and differentiation of MG-63 cells, which implied the materials possessed excellent biocompatibility and had a wide potential in biomedical application. [Copyright &y& Elsevier]

Abstract: Novel composite films of Bombyx mori silk fibroin (SF) and hydroxyapatite (HA) composite films, with glycerin as an additive, were fabricated by means of co-precipitation, where the theoretical HA content was varied from 2 (w/w)% to 31 (w/w)%. The structure and properties of the composite films were investigated by SEM, XRD, AFM, TGA and tensile testing. The results showed that the composite films were smooth and transparent with the uniform distribution of HA into the composites when the final HA content was lower than 21 (w/w)%. XRD and TGA data showed that the silk fibroin in the composites was predominantly in a β-sheet crystalline structure, which was induced not only by the addition of glycerin, also by the HA crystal growth during the composite fabrication, leading to the thermal stable composite films. On the other hand, the HA crystals had the anisotropic growth with high extent of lattice imperfection and the preferential orientation along c-axis, probably promoted by the silk fibroin. The mechanical testing results showed that both break strain and stress were declined with the increase of HA content in the composites, presumably due to the original brittleness of HA compound. [Copyright &y& Elsevier]

Abstract: Bombyx mori silk fibroin is of practical interest for its excellent intrinsic properties utilizable in the biotechnological and biomedical fields. Here, the silk fibroin films were pretreated with different methods and then used as the template for the hydroxyapatite (HA) crystal growth. To study the effect of silk films’ surface structure on the protein biomineralization, the films were immersed into 1.5 times simulated body fluid (1.5×SBF) to induce the HA deposition at 37°C. The results showed that an anisotropic growth of HA crystals was observed on the different films as judging from XRD, TEM and HRTEM data. This was thought that the positions and density of carboxyl groups, Cno groups on the surface of SF films may be different, which play the key effect on HA crystal growth. [Copyright &y& Elsevier]

Abstract: The purpose of this study was to investigate the effect of silk sericin (SS) on the morphology and crystallinity of hydroxyapatite (HAp) crystals synthesized at the pH 7.4–12 and 50°C via a biomimetic method. Using X-ray diffraction (XRD), transmission electron microscope (TEM) and high-resolution transmission electron microscope (HRTEM), it was revealed that a homogeneous assembly could be obtained in the presence of SS, which held a highly ordered microstructure and poor crystallinity. But in the absence of SS, an oriented aggregate could be prepared at 50°C and pH 10, which held more confused crystal lattice lines. The results proved that the biomimetic structure of HAp could be constructed under the controlled reaction conditions, which may offer a new clue on the understanding of the process of biomineralization. [ABSTRACT FROM AUTHOR]