Bioceramics 19

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Authors: Wen Qian Xiao, Yu Mei Xiao, Xian Tao Wen, Hong Song Fan, Xing Dong Zhang
Abstract: In order to prepare nano-hydroxyapatite/poly(lactide) (n-HA/PLA) composite with good interfacial interaction, some groups which could bind with Ca ions in HA crystals need to be introduced onto PLA surface. Poly(α-methacrylic acid) (PMAA) was grafted on the PLA surfaces via photooxidization and subsequent UV induced polymerization. Suspension of PMAA-PLA microparticles with an average size as 133.1nm was prepared with solvent evaporation technique. Then utilizing the action of template manipulating of PMAA-PLA microparticles, n-HA/PLA composite were synthesized. Zeta potentials measurement and SEM indicated that there were good interfacial interactions between two phases of n-HA/PLA composite. The results of cell viability confirmed that n-HA/PLA composite possessed good cytocompatibility, so the n-HA/PLA composite scaffold obtained by electrospun technology might be used as bone tissue engineering scaffold.
Authors: Kiyotaka Yamada, Masahiro Nawa, Giuseppe Pezzotti
Abstract: Zirconia ceramics have been widely used for new generation of bearing materials in biomedical applications. In this context, a zirconia-matrix, stabilized with cerium oxide and dispersed with fine alumina particles (Ce-TZP/Al2O3 nanocomposite) was recently developed and this material experienced significant improvements in both fracture toughness and strength above the standard mechanical performance of monolithic zirconia. In this paper, we used confocal Raman spectroscopy to provide quantitative assessments with high spatial resolution of phase structure and residual stress fields developed in the Ce-TZP/Al2O3 nanocomposite. According to confocal Raman spectroscopy, we have directly visualized patterns of phase transformation and residual stress fields stored on the very surface of the material around an indentation print. These spectroscopic assessments may open a perspective in understanding the micromechanical behavior of the Ce-TZP/Al2O3 nanocomposite when subjected to local surface impingement and shocks.
Authors: M. M. Xu, Fang Mei, Dan Li, Xiao Ping Yang, Gang Sui, Xu Liang Deng, X. Y. Hu
Abstract: Efficacy of poly(L-lactic acid) (PLLA)/nano-hydroxyapatite(HA) hybrid nanofibrous scaffolds for dental tissue engineering is described and their performance on normal cells with MG-63 is compared as well in this study. Perfectly PLLA/HA fibrous scaffolds were fabricated by an electrospinning process under optimal condition. Cell culcure and adenovirus encoding green fluorenscent protein technique were used to study the morphology of cells grown on the scaffolds. The results show that the growth of DPSCs and PCs is well observed attached to the PLLA/HA fibers, as well as MG-63, which indicate that the nanofibrous PLLA/HA scaffold could be used as a potential cell carrier in dental tissue engineering.
Authors: H. Li, Khiam Aik Khor, W.N. Chen, T.L. Tan, H. Pan, P. Cheang
Abstract: A big variety of bioceramics have been successfully utilized as implant materials for promoting fixation of bony tissues. Different bioceramics exhibited markedly different proliferation rates of the osteoblast cells in vitro. Clarification of the mechanism about the attachment and proliferation/differentiation of the cells would contribute to selecting suitable biomaterials for hard tissue replacement. Proteomics study was performed in this study employing the 2-dimensional electrophoresis assay with an aim of recognizing the changes in proteins. Nanostructured hydroxyapatite (HA) coatings have been fabricated and they have shown promising mechanical performances. Results showed that the nanostructured HA coatings promoted proliferation of the osteoblast cells. Alkaline phosphatase (ALP) assay revealed an increased ALP activity of the proliferated viable cells, and obviously the presence of the nanosized pores can enhance the anchoring and stretching of the cells. No obvious difference in the 2-D gel maps taken for the cells proliferated on the HA coating and for control can be found. This in turn suggests that the nanostructured HA coating induces minor changes in proteins of the cells.
Authors: Zhi Jun Pan, Bing Gang Guan, Di Sheng Yang, Jie Feng, Wei Qi Yan
Abstract: Biomimetic nanoapatite coatings was developed by functionally modified methods with a combination of topographic, chemical and biomimetic treatments on the surface of titanium (Ti) substrate. The biological behavior and bioactivity of functionally modified SLA implants with chemical and biomimetic treatments (SCB-treated Ti) using body like solution were investigated to compare with untreated Ti and SLA Ti plates as controls. The cell attachment, proliferation, alkaline phosphotatse (AKP) activity, cell morphology and differentiation were evaluated by using MTT, RT-PCR, scanning electron microscopy (SEM) and confocal laser-scanning microscope (CLSM) analysis system. The results showed that the cell adhesion and proliferation was enhanced on functionalized titanium surface with nano-scale apatite compared to the controls. SEM micrographs also revealed that the osteoblast-like cells spreadly grew along the surface. Cell morphology and differentiation could be further observed distinctly by CLSM graphs. Moreover, mRNA expression of alkaline phosphotatse in nucleus on the SCB-treated Ti increased obviously on the third day compared with the controls. The in vitro results demonstrated the remarkable improvement on cell adhesion and proliferation of the biomimetic nanoapatite on SCB-treated Ti, which could be used for orthopaedic/dental implants.
Authors: M. Dutour Sikirić, Csilla Gergely, F. Cuisinier, Helga Füredi-Milhofer
Abstract: In the production of artificial bone and tooth implants, coating of the surfaces of hard, but bioinert materials (metals, polymers) with calcium phosphate crystals has been used to improve bioactivity and facilitate osteointegration. Recently low temperature methods, involving precipitation from aqueous solutions (biomimetic precipitation) including coprecipitation of specific organic macromolecules (growth hormones, enzymes, proteins) have been developed. In this paper an alternative approach is presented, which consists in first laying down a matrix consisting of polyelectrolyte multilayers (PE MLs) alternating with layers of amorphous calcium phosphate (ACP) particles and subsequently growing calcium phosphate crystals upon/within the multilayers. This attractive approach leads to the formation of a new class of true organic-inorganic nanocomposite coatings. In a previous communication we have shown preliminary results, which point to the feasibility of this approach [1]. Here we describe in detail the design, synthesis and characteristics of the thus obtained nanocomposite coatings.
Authors: Xu Liang Deng, M. M. Xu, Dan Li, Gang Sui, X. Y. Hu, Xiao Ping Yang
Abstract: Novel Poly(l-lactic acid) (PLLA)/ Multi-walled carbon nanotubes (MWNTs)/ hydroxyapatite (HA) nanofibrous scaffolds with high porosity and well-controlled pore architectures were prepared via electrospinning techniques. The structure, morphology, molecular weight change of the scaffolds were investigated using scanning electron microscopy (SEM). The results noticed that the average diameter of hybrid nanofiber was similar to that of PLLA/HA fiber, but the surface of hybrid fibers was much coarser because of the introduction of MWNTs nano-particles. The biocompatibility of the scaffold has been investigated by human Dental Pulp Stem Cells (DPSCs) cell culture on the scaffold. The preliminary results showed that cells were well adhered and proliferated on the hybrid scaffolds as well as PLLA/HA fibers. Based on the experimental observations, the aligned nanofibrous PLLA/ MWNTs /HA scaffold could be used as a potential candidate scaffold in dental tissue engineering.
Authors: Bing Gang Guan, Di Sheng Yang, Zhong Li Shi, Wen Jian Weng, Wei Qi Yan
Abstract: A novel biomimetic composite consisted of nano β-tricalcium phosphate and collagen (n-TCP/Col.), having similar structure with the natural bone, was produced by a wet-chemical method. The biological effect with and without n-TCP/Col on bone repair and regeneration was evaluated by histological and radiological examination in a rabbit femoral condyle model. The results showed that radiopacity of implant decreased gradually and began to increase at 12 weeks, while no obvious changes for the control. Histological results revealed that trabecular bone formed around the implant at 4 weeks and increased at 8 weeks; By 12 weeks, bone filling with Harvard’s system was observed around the implant. By contrast, only loose connective tissue was seen in control group. This was further illuminated by fluorescence microscopy. The results of this study suggested that the novel nano β-tricalcium phosphate and collagen composite possessed good properties of osteoconductivity and degradation in the biological environment, which could have potential application as a promising bone substitute.
Authors: M. Dutour Sikirić, Rene Elkaim, S. Lamolle, H.J. Ronold, S.P. Lyngstadass, Helga Füredi-Milhofer, F. Cuisinier
Abstract: Biological mineralization proceeds within an organic matrix and is induced and controlled by extracellular, highly acidic matrix macromolecules. Our group has recently prepared organic-inorganic nanocomposite coatings by a strategy that closely mimics these processes. The strategy involves depositing a matrix of polyelectrolyte multilayers (PE MLs), alternating with layers of amorphous calcium phosphate (ACP) particles, then "in situ" growing nanosized apatite crystals within that matrix [1, 2]. Here we describe the results of biological "in vitro" and "in vivo" testing of these materials.
Authors: Xiao Ying Lu, Zh. Liu, Jie Weng
Abstract: The cylindrical chitosan (CS)/hydroxyapatite (HA) nanocomposites were hydrothermally prepared via in situ precipitation and characterized by x-ray diffractometer (XRD), Fourier transform infrared spectrometer (FT-IR), thermogravimetry (TG) and scanning electronic microscope (SEM). The results show that the as-prepared products are composed of CS and low-crystalline HA phases, and some extent of interaction between CS and HA phases exists in the composites, which is greatly influenced by the temperature and pH value in the hydrothermal process. The crystal size of HA uniform-distributed in CS matrix is calculated to be no larger than 100nm while the crystallinity of CA is greatly increased in the hydrothermal process, which is beneficial to the mechanical properties of the composites. It is proposed that the nano-structure of HA/CS composite will have the better biomedical properties in the biomaterials applications.

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