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Paper Title Page
Abstract: Zirconium oxide (ZrO2) nanoparticles with the sizes of 50 nm were prepared via hydrothermal method and utilized to prepare zirconia/polyacrylamide (ZrO2/PAAm) nanocomposite hydrogels through conventional radical polymerization at mild condition. The morphology and crystalline structure of prepared ZrO2 were characterized by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD), and the resultant ZrO2/PAAm nanocomposite hydrogels were characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and dental ray machines. The results show that the ZrO2/PAAm nanocomposite hydrogels have a certain X-ray radiopacity and stability under simulated human oral conditions, which have the great potential to be used as root canal filling materials.
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Abstract: Porous Ti6Al4V alloys with anisotropic structure for biomedical application was fabricated by diffusion bonding of titanium alloy meshes. Compressive mechanical compatibility of the alloys is investigated as human bone implants. It is concluded that the fabrication processing for porous Ti6Al4V alloys has better control of the porosity. The pore structure of porous titanium is anisotropic, with elongated and square pores in the out-of-plane and in-plane direction, respectively, which is suited for bone ingrowth. The compressive Young’s modulus and yield stress of porous Ti6Al4V alloy compressed in the out-of-plane direction are 12.2 GPa and 171.4 MPa, respectively, which is compatible with those for the cortical bones.
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Abstract: Two pH-responsive block glycopolymers, poly (ethylene glycol)-b-Poly (2- (diethylamino) ethyl methacrylate-co-2-gluconamidoethyl methacrylate) (PEG113-b-P(DEA55-co-GAMA12)) and poly (ethylene glycol)-b-poly (2-(diethylamino) ethyl methacrylate)-b-poly (2-gluconamido ethyl methacrylate) (PEG113-b-PDEA55-b-PGAMA15), were synthesized via atom transfer radical polymerization (ATRP) by directly or successively polymerization of GAMA and DEA monomers using a PEG-based macroinitiator, respectively, without protecting group chemistry. Those block glycopolymers were confirmed by proton Nuclear Magnetic Resonance (1H NMR) and Gel Permeation Chromatography (GPC), and their self-assembly behaviors were characterized by Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS) and Zeta-potential. The results show both synthetic block glycopolymers were dissolved molecularly in aqueous solution at acidic pH (such as pH 3), thus it can reversibly convert to be two-layer micelles comprising DEA and GAMA cores, PEG coronas with size of around 50 nm, or micelles comprising DEA cores, GAMA and PEG outer coronas with bigger size of 70 nm for PEG113-b- P(DEA55-co-GAMA12) and PEG113-b-PDEA55-b-PGAMA15), respectively, at basic condition. Both glycopolymers have the micellization process at middle pH (pH 6-8), but possess different isoelectric points (pIs) (at pH 8.0 and 7.8) for their pH responsive block of PEG113-b-P(DEA55-co-GAMA12) and PEG113-b-PDEA55-b-PGAMA15 with DEA-co-GAMA random structure or DEA chain only, respectively. This study not only reveals the self-assembly of pH responsive block glycopolymers with different architectures by fixing similar degree polymerization (DP) of their blocks, but also provides a tool to investigate pH induced dynamic covalent interaction between glycopolymers and phenylboronic acid derivatives or a light for designing novel drug delivery carriers.
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Abstract: In order to solve the problem that low pore connectivity of the spherical porous ceramic, bionic structure porous alumina ceramics with spherical/lamellar pores were fabricated combining the adding pore-forming agent and two step freeze casting. The effects of fabrication parameters of the samples on morphologies, porosity and pore connectivity are investigated. The mechanical and biological properties of bionic structure porous alumina ceramics are also characterized. Results show that porous alumina ceramics with spherical/lamellar pores are obtained, and the lamellar pores pass through the spherical pores, which prove the pore connectivity reach 86.2 %. The mechanical properties are improved by porosity gradient from the inside (highly porous) to the outside (less porous) of porous alumina. Bionic structure porous alumina ceramics with spherical/lamellar pores have better cell growth and absorbance than those with spherical or lamellar pores only since its high pore connectivity.
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Abstract: Aiming at inadequate mechanical properties of Glass ionomer cement (GIC) commonly used in dental clinic, commercial and melt quenched GIC powders as control groups, homemade GIC powder was prepared by sol–gel route and modified by Nb2O5. The GIC samples were characterized by X-ray Diffraction (XRD), particle size analysis, Scanning Electron Microscope (SEM) and Fourier Transform Infrared (FT-IR). The compressive strength, Vickers hardness, working and net setting time were tested. The data was analyzed by one-way ANOVA. The XRD results showed that commercial, melt quenched and sol gel GIC powders were similar amorphous. D90 of three GIC powders and Nb2O5 powder were 26 μm, 17 μm, 29 μm and 19 μm respectively. 5% Nb2O5-GIC exhibited the highest values of compressive strength and Vickers hardness, which were 112.93 Mpa, 139.48 MPa and 142.25 MPa respectively, increased 19.11%, 30.56% and 16.51% (P <0.05); the Vickers hardness were 35.15 MPa, 36.23 MPa and 37.62 MPa, increased 18.03%, 29.95% and 16.32% (P <0.05) compared to those of unmodified GICs as well. There was no significant change of the FT-IR characteristic peaks of modified GIC. The working time of three kinds of GIC were 4'58 ", 3'28" and 4'10 ", the net setting time were 5'16", 3'15 "and 4'38" (standard is 1.5-6 minutes). It was concluded that the dispersion stiffened effect of niobium oxide could improve the mechanical properties of the filling GIC without affecting the clinical operating performance.
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Abstract: Electrospinning is a versatile and efficient technique for fabricating nanofibrous tissue engineering scaffolds. However, problems such as small pore size of electrospun scaffolds have limited their applications for tissue regeneration. It is important to modify/improve existing electrospinning techniques for fully realizing the potential of both the electrospinning technology and electrospun nanofibrous scaffolds. To increase the pore size of scaffolds prepared by conventional electrospinning technology, in the present study, a hybrid fabrication technique by combining electrospinning with phase separation is utilized. Polymer solutions were made using mixed solvent of (a) DCM and DMF or (b) chloroform and DMF and electrospun fibers were deposited in ice water, ice methanol or liquid nitrogen. It was shown that for poly (ε-caprolactone) (PCL) scaffolds, the hybrid technique could maintain the nanofibrous structure for scaffolds and control the pore size in scaffolds. As compared with pore sizes in PCL scaffolds made by conventional electrospinning, pores were larger in PCL scaffolds produced by the hybrid technique.
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Abstract: Emulsion electrospun nanofibrous tissue engineering scaffolds made by conventional positive voltage electrospinning (PVES) have various advantages for growth factor (GF) delivery. But problems such as high initial burst release still exist. Negative voltage electrospinning (NVES) may produce nanofiberous scaffolds that can modulate the release behavior of GFs which bear positive electrical charges. By using either PVES or NVES for emulsion electrospinng, the present study investigated the influence of NVES and applied voltage on the release behavior of a typical GF bearing the positive charge, basic fibroblast growth factor (bFGF), encapsulated in the nanofibers of poly (lactic-co-glycolic acid) (PLGA) scaffolds. Emulsions were firstly prepared by mixing a bFGF-containing aqueous solution and a PLGA solution. They were then subjected to electrospinning under either a positive voltage (10, 15, or 20 kV) or a negative voltage (-10, -15, or-20 kV). The morphology and structure of fibers and scaffolds were subsequently characterized. All scaffolds were nanofibrous and the nanofibers exhibited core-shell structures, with the bFGF-containing water phase forming the fiber core. Scaffolds exhibited the same type of electrical charges as the type of the applied voltage for electrospinning, i.e., scaffold made by PVES showed positive charges while scaffold fabricated by NVES possessed negative charges. The intensity of positive or negative charges borne by scaffolds and their retention time on scaffolds increased with an increase in the absolute value of the applied voltage (⏐V⏐). In vitro bFGF release experiments were conducted for scaffolds made by either NVES or PVES. Results showed that the bFGF release behavior was modulated by NVES.
385
Abstract: In order to improve the cell biocompatibility of pure iron surface as cardio-vascular stent material, Fe-O film was deposited on single crystal silicon by unbalanced magnetron sputtering. Human umbilical vein endothelial cells were seeded on the 316L SS, pure iron and Fe-O film surface, whereafter cultured in vitro. Adhesion behavior was detected after 2 h incubation. Cell morphology and proliferation activities were assessed at 1, 3 and 5 days. The results show that the endothelial cells are easy to adhere and spread on the surface of Fe-O film. Compared with 316L SS samples, the cells count and area coverage of Fe-O film in 1 and 5 days make a difference significantly. These results demonstrated that the Fe-O film prepared by unbalanced magnetron sputtering technique has good cytocompatibility.
390
Abstract: In order to repair the etched human dental enamel, 45S5 bioactive glass with different particle size was used to remineralization enamel in vitro. 45S5 bioactive glass powder was sieved, and divided into the three groups. Freshly sound human second molar teeth from patients were extracted and specimens of dentine-enamel junction were prepared under water-cooled diamond saw, then the enamel surface was polished and finally rinsed. The enamel samples were soaked in simulated oral fluid (SOF) for 5 days. Particle size distribution, topological images and mechanical properties such as hardness and reduced modulus of enamel surface were evaluated by the laser particle size analyzer, atomic force microscope (AFM) and nanoindentation technology. The results indicated that the adhered particle size onto the enamel surface was concentrated on the 1-10 μm. With the decreasing particle size, adhesive capacity onto the enamel surface increased, but the mechanical properties decreased gradually after soaking in SOF for 5 days. In a short period time, Group 2 particles are suitable of repair the etched enamel, and further improve its mechanical properties. This study suggests that proper size 45S5 bioactive glass may be used to repair the acid etched teeth as a toothpaste additive.
396
Fabrication and Characteristics of Gene-Delivering Nanodevices Based on Au-Ag@CS-FA Hybrid Particles
Abstract: Gene therapy has great potential in offering highly promising treatments for cancer. Polymer-metal hybrid nanoparticles (NPs) are good candidates as gene delivery vehicles due to their unique properties and facile functionalization. The polymer component in hybrid NPs can provide accurate cancer cell targeting and high DNA binding ability while the metallic component can provide imaging functions for the nanodevices. In the present study, hybrid NPs comprising an Au-Ag bimetallic core and a folic acid-chitosan shell (Au-Ag@CS-FA) were fabricated. The structure and relevant properties of Au-Ag@CS-FA NPs were subsequently studied using a variety of techniques,like scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), transmission electron microscope (TEM) and UV-visible spectra. Their DNA binding ability was also assessed. Results showed that Au-Ag@CS-FA NPs possessed properties that can make them excellent gene delivery vehicles.
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