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Stem cell homing-based tissue engineering using bioactive materials
Yinxian YU, Binbin SUN, Chengqing YI, Xiumei MO
Front. Mater. Sci.. 2017, 11 (2): 93-105.
https://doi.org/10.1007/s11706-017-0373-0
Tissue engineering focuses on repairing tissue and restoring tissue functions by employing three elements: scaffolds, cells and biochemical signals. In tissue engineering, bioactive material scaffolds have been used to cure tissue and organ defects with stem cell-based therapies being one of the best documented approaches. In the review, different biomaterials which are used in several methods to fabricate tissue engineering scaffolds were explained and show good properties (biocompatibility, biodegradability, and mechanical properties etc.) for cell migration and infiltration. Stem cell homing is a recruitment process for inducing the migration of the systemically transplanted cells, or host cells, to defect sites. The mechanisms and modes of stem cell homing-based tissue engineering can be divided into two types depending on the source of the stem cells: endogenous and exogenous. Exogenous stem cell-based bioactive scaffolds have the challenge of long-term culturing in vitro and for endogenous stem cells the biochemical signal homing recruitment mechanism is not clear yet. Although the stem cell homing-based bioactive scaffolds are attractive candidates for tissue defect therapies, based on in vitrostudies and animal tests, there is still a long way before clinical application.
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Si-doping bone composite based on protein template-mediated assembly for enhancing bone regeneration
Qin YANG, Yingying DU, Yifan WANG, Zhiying WANG, Jun MA, Jianglin WANG, Shengmin ZHANG
Front. Mater. Sci.. 2017, 11 (2): 106-119.
https://doi.org/10.1007/s11706-017-0375-y
Bio-inspired hybrid materials that contain organic and inorganic networks interpenetration at the molecular level have been a particular focus of interest on designing novel nanoscale composites. Here we firstly synthesized a series of hybrid bone composites, silicon-hydroxyapatites/silk fibroin/collagen, based on a specific molecular assembled strategy. Results of material characterization confirmed that silicate had been successfully doped into nano-hydroxyapatite lattice. In vitro evaluation at the cellular level clearly showed that these Si-doped composites were capable of promoting the adhesion and proliferation of rat mesenchymal stem cells (rMSCs), extremely enhancing osteoblastic differentiation of rMSCs compared with silicon-free composite. More interestingly, we found there was a critical point of silicon content in the composition on regulating multiple cell behaviors. In vivo animal evaluation further demonstrated that Si-doped composites enabled to significantly improve the repair of cranial bone defect. Consequently, our current work not only suggests fabricating a potential bone repair materials by integrating element-doping and molecular assembled strategy in one system, but also paves a new way for constructing multi-functional composite materials in the future.
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Crystal-chemistry insight into the photocatalytic activity of BiOClxBr1--x nanoplate solid solutions
Huan-Yan XU, Xu HAN, Qu TAN, Ke-Jia WU, Shu-Yan QI
Front. Mater. Sci.. 2017, 11 (2): 120-129.
https://doi.org/10.1007/s11706-017-0379-7
In this study, a facile alcoholysis method was developed to synthesize BiOClxBr1--x nanoplates at room temperature and atmospheric pressure. In this route, strong acid or alkaline environment was absolutely avoided to realize the high exposure of {001} crystal facets. The regular changes in XRD peaks and cell parameters as a function of the Br content strongly declared that the obtained BiOClxBr1--x products belonged to a group of solid solutions. The 2D nanosheets with in-plane wrinkles were clearly observed in TEM images. Interestingly, as the Br content increased, band gaps of BiOClxBr1--x solid solutions gradually decreased. The photocatalytic degradation of RhB under simulated sunlight irradiation indicated that BiOCl0.5Br0.5 had the best photocatalytic activity. From the viewpoint of crystal chemistry, the photocatalytic activity of BiOClxBr1--x solid solutions was closely related with the exposure amount of {001} facets, interlayer spacing of (001) plane and energy-level position of valence band.
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Environmentally benign chitosan as reductant and supporter for synthesis of Ag/AgCl/chitosan composites by one-step and their photocatalytic degradation performance under visible-light irradiation
Hao WANG, Yuhan WU, Pengcheng WU, Shanshan CHEN, Xuhong GUO, Guihua MENG, Banghua PENG, Jianning WU, Zhiyong LIU
Front. Mater. Sci.. 2017, 11 (2): 130-138.
https://doi.org/10.1007/s11706-017-0383-y
A novel Ag/AgCl/chitosan composite photocatalyst was successfully prepared by a simple one-step method. During this progress, environmentally benign chitosan not only served as reductant to reduce Ag+ to Ag0 species, but also acted as supporter for Ag/AgCl nanoparticles. XRD, SEM, EDX, UV-vis DRS and XPS were employed to characterize the as-prepared simples. SEM images of Ag/AgCl/chitosan composites revealed that Ag/AgCl nanoparticles were successfully loaded onto chitosan without obvious aggregation. All Ag/AgCl/chitosan composites exhibited efficient photocatalytic activity for the degradation of rhodamine B (RhB) under visible-light irradiation. The result of photocatalytic degradation experiment indicated that 20% of the mass ratio of AgCl to chitosan was the optimum, and after 40 min photocatalytic reaction, the degradation rate reached about 96%.
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Facile synthesis and electrochemical properties of layered Li[Ni1/3Mn1/3Co1/3]O2 as cathode materials for lithium-ion batteries
Yingfang ZHU, Jingwei YOU, Haifu HUANG, Guangxu LI, Wenzheng ZHOU, Jin GUO
Front. Mater. Sci.. 2017, 11 (2): 155-161.
https://doi.org/10.1007/s11706-017-0374-z
A layered oxide Li[Ni1/3Mn1/3Co1/3]O2 was synthesized by an oxalate co-precipitation method. The morphology, structural and composition of the as-papered samples synthesized at different calcination temperatures were investigated. The results indicate that calcination temperature of the sample at 850°C can improve the integrity of structural significantly. The effect of calcination temperature varying from 750°C to 950°C on the electrochemical performance of Li[Ni1/3Mn1/3Co1/3]O2, cathode material of lithium-ion batteries, has been investigated. The results show that Li[Ni1/3Mn1/3Co1/3]O2 calcined at 850°C possesses a higher capacity retention and better rate capability than other samples. The reversible capacity is up to 178.6 mA·h·g−1, and the discharge capacity still remains 176.3 mA·h·g−1 after 30 cycles. Moreover, our strategy provides a simple and highly versatile route in fabricating cathode materials for lithium-ion batteries.
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Electronic structure and bonding interactions in Ba1--xSrxZr0.1Ti0.9O3 ceramics
Jegannathan MANGAIYARKKARASI, Subramanian SASIKUMAR, Olai Vasu SARAVANAN, Ramachandran SARAVANAN
Front. Mater. Sci.. 2017, 11 (2): 182-189.
https://doi.org/10.1007/s11706-017-0376-x
An investigation on the precise electronic structure and bonding interactions has been carried out on Ba1−xSrxZr0.1Ti0.9O3 (short for BSZT, x = 0, 0.05, 0.07 and 0.14) ceramic systems prepared via high-temperature solid state reaction technique. The influence of Sr doping on the BSZT structure has been examined by characterizing the prepared samples using PXRD, UV-visible spectrophotometry, SEM and EDS. Powder profile refinement of X-ray data confirms that all the synthesized samples have been crystallized in cubic perovskite structure with single phase. Charge density distribution of the BSZT systems has been completely analyzed by the maximum entropy method (MEM). Co-substitution of Sr at the Ba site and Zr at the Ti site into the BaTiO3 structure presents the ionic nature between Ba and O ions and the covalent nature between Ti and O ions, revealed from MEM calculations. Optical band gap values have been evaluated from UV-visible absorption spectra. Particles with irregular shapes and well defined grain boundaries are clearly visualized from SEM images. The phase purity of the prepared samples is further confirmed by EDS qualitative spectral analysis.
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Microstructure and mechanical properties of tungsten composite reinforced by fibre network
Linhui ZHANG, Yan JIANG, Qianfeng FANG, Zhuoming XIE, Shu MIAO, Longfei ZENG, Tao ZHANG, Xianping WANG, Changsong LIU
Front. Mater. Sci.. 2017, 11 (2): 190-196.
https://doi.org/10.1007/s11706-017-0378-8
In this paper the tungsten-fibre-net-reinforced tungsten composites were produced by spark plasma sintering (SPS) using fine W powders and commercial tungsten fibres. The relative density of the samples is above 95%. It was found that the recrystallization area in the fibres became bigger with increasing sintering temperature and pressure. The tungsten grains of fibres kept stable when sintered at 1350°C/16 kN while grown up when sintered at 1800°C/16 kN. The composite sintered at 1350°C/16 kN have a Vickers-hardness of ~610 HV, about 2 times that of the 1800°C/16 kN sintered one. Tensile tests imply that the temperature at which the composites (1350°C/16 kN) begin to exhibit plastic deformation is about 200°C–250°C, which is 400°C lower than that of SPSed pure W. The tensile fracture surfaces show that the increasing fracture ductility comes from pull-out, interface debonding and fracture of fibres.
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