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Binary phase solid-state photopolymerization of acrylates: design, characterization and biomineralization of 3D scaffolds for tissue engineering
Inamullah MAITLO, Safdar ALI, Muhammad Yasir AKRAM, Farooq Khurum SHEHZAD, Jun NIE
Front. Mater. Sci.. 2017, 11 (4): 307-317.
https://doi.org/10.1007/s11706-017-0394-8
Porous polymer scaffolds designed by the cryogel method are attractive materials for a range of tissue engineering applications. However, the use of toxic cross-linker for retaining the pore structure limits their clinical applications. In this research, acrylates (HEA/PEGDA, HEMA/PEGDA and PEGDA) were used in the low-temperature soli d-state photopolymerization to produce porous scaffolds with good structural retention. The morphology, pore diameter, mineral deposition and water absorption of the scaffold were characterized by SEM and water absorption test respectively. Elemental analysis and cytotoxicity of the biomineralized scaffold were revealed by using XRD and MTT assay test. The PEGDA-derived scaffold showed good water absorption ability and a higher degree of porosity with larger pore size compared to others. XRD patterns and IR results confirmed the formation of hydroxyapatite crystals from an alternative socking process. The overall cell proliferation was excellent, where PEGDA-derived scaffold had the highest and the most uniform cell growth, while HEMA/PEGDA scaffold showed the least. These results suggest that the cell proliferation and adhesion are directly proportional to the pore size, the shape and the porosity of scaffolds.
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Regulation of RAW 264.7 macrophages behavior on anodic TiO2 nanotubular arrays
Shenglian YAO, Xujia FENG, Wenhao LI, Lu-Ning WANG, Xiumei WANG
Front. Mater. Sci.. 2017, 11 (4): 318-327.
https://doi.org/10.1007/s11706-017-0402-z
Titanium (Ti) implants with TiO2 nanotubular arrays on the surface could regulate cells adhesion, proliferation and differentiation to determine the bone integration. Additionally, the regulation of immune cells could improve osteogenesis or lead in appropriate immune reaction. Thus, we evaluate the behavior of RAW 264.7 macrophages on TiO2 nanotubular arrays with a wide range diameter (from 20 to 120 nm) fabricated by an electrochemical anodization process. In this work, the proliferation, cell viability and cytokine/chemokine secretion were evaluated by CCK-8, live/dead staining and ELISA, respectively. SEM and confocal microscopy were used to observe the adhesion morphology. Results showed that the small size nanotube surface was benefit for the macrophages adhesion and proliferation, while larger size surface could reduce the inflammatory response. These findings contribute to the design of immune-regulating Ti implants surface that supports successful implantation.
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Folate-conjugated pH-responsive nanocarrier designed for active tumor targeting and controlled release of doxorubicin
Lulu WEI, Beibei LU, Lin CUI, Xueying PENG, Jianning WU, Deqiang LI, Zhiyong LIU, Xuhong GUO
Front. Mater. Sci.. 2017, 11 (4): 328-343.
https://doi.org/10.1007/s11706-017-0401-0
A novel type of amphiphilic pH-responsive folate-poly(ε-caprolactone)-block-poly(2-hydroxyethylmethacrylate)-co-poly(2-(dimethylamino)-ethylmethacrylate) (FA-PCL-b-P(HEMA-co-DMAEMA)) (MFP) block copolymers were designed and synthesized via atom transfer radical polymerization (ATRP) and ring opening polymerization (ROP) techniques. The molecular structures of the copolymers were confirmed with1H NMR, FTIR and GPC measurements. The critical micelle concentration (CMC) of MFP in aqueous solution was extremely low (about 6.54 mg/L). Thein vitro release behavior of DOX-loaded micelles was significantly accelerated when the pH value of solution decreased from 7.4 to 5.0. In vitro antitumor efficiency was evaluated by incubating DOX- loaded micelles with Hela cells. The results demonstrated that this copolymer possessed excellent biocompatibility, and FA-decorated micelles MFP showed higher cellular uptake than those micelles without the FA moiety, indicating their unique targetability. These folate-conjugated biodegradable micelles are highly promising for targeted cancer chemothe-rapy.
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Ga2O3 doping and vacancy effect in KNN--LT lead-free piezoceramics
Zhi TAN, Jie XING, Laiming JIANG, Jianguo ZHU, Bo WU
Front. Mater. Sci.. 2017, 11 (4): 344-352.
https://doi.org/10.1007/s11706-017-0403-y
Ga2O3 was doped into 0.95(K0.48Na0.52)NbO3–0.05LiTaO3 (KNN–LT) ceramics and its influences on the sintering behavior, phase structure and electrical properties of ceramics were studied. Firstly, SEM observation exhibits that more and more glass phase appears in ceramics with the gradual addition of Ga2O3, which determines the continuous decrease in sintering temperatures. And the addition of Ga2O3 is also found to increase the orthorhombic–tetragonal transition temperature (TO–T) of system to a higher level. Secondly, both the density and the coercive?field (EC) of ceramics increase firstly and then decrease with increasing the Ga2O3 content, and the KNN–LT–xGa sample at x = 0.004 shows a pinched P–E hysteresis loop. Finally, the impedance characteristics of KNN–LT–xGa ceramics were investigated at different temperatures, revealing a typical vacancy related conduction mechanism. This work demonstrates that Ga2O3 is a good sintering aid for KNN-based ceramics, and the vacancy plays an important role in the sintering and electrical behaviors of ceramics.
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Microwave synthesis of chain-like zircona nanofibers through carbon-induced self-assembly growth
Wanyu ZHAO, Jian LI, Bingbing FAN, Gang SHAO, Hailong WANG, Bozhen SONG, Shengnan WEI, Rui ZHANG
Front. Mater. Sci.. 2017, 11 (4): 353-357.
https://doi.org/10.1007/s11706-017-0397-5
Chain-like zircona (ZrO2) nanofibers were prepared by microwave sintering without any surfactants or solid templates. Microwave sintering was conducted in a multimode microwave cavity with TE666 resonant mode at 2.45 GHz. Carbon particles were used to activate unique thermal processes when mixed with ZrO2 precursor. The sintering condition was at 1300°C for 10 min. Samples were characterized by XRD, SEM, TEM techniques. It was found that both monolithic and tetragonal ZrO2 co-existed in samples prepared from the mixture of ZrO2 precursors and carbon by either microwave or conventional sintering. Only m-ZrO2 exists in samples prepared by ZrO2 precursors without carbon. ZrO2 appeared as chain-like nanofibers, which might be attributed to a so-called carbon-induced self-assembly growth mechanism.
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Photocatalytic mechanism of high-activity anatase TiO2 with exposed (001) facets from molecular-atomic scale: HRTEM and Raman studies
Jun WU, Chentian SHI, Yupeng ZHANG, Qiang FU, Chunxu PAN
Front. Mater. Sci.. 2017, 11 (4): 358-365.
https://doi.org/10.1007/s11706-017-0398-4
Anatase TiO2 with a variant percentage of exposed (001) facets was prepared under hydrothermal processes by adjusting the volume of HF, and the photocatalytic mechanism was studied from atomic-molecular scale by HRTEM and Raman spectroscopy. It was revealed that: 1) From HRTEM observations, the surface of original TiO2 with exposed (001) facets was clean without impurity, and the crystal lattice was clear and completed; however, when mixed with methylene blue (MB) solution, there were many 1 nm molecular absorbed at the surface of TiO2; after the photocatalytic experiment, MB molecules disappeared and the TiO2 lattice image became fuzzy. 2) The broken path of the MB chemical bond was obtained by Raman spectroscopy, i.e., after the irradiation of the light, the vibrational mode of C−N−C disappeared due to the chemical bond breakage, and the groups containing C−N bond and carbon rings were gradually decomposed. Accordingly, we propose that the driving force for breaking the chemical bond and the disappearance of groups is from the surface lattice distortion of TiO2 during photocatalyzation.
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