Papers by Author: Cheng Yun Ning

Abstract: Titania nanotube (NT) arrays with a length of 550nm were fabricated on the flat titanium substrate by anodization. The microstructure was identified by scanning electron microscope. The composition has been investigated with X-ray photoelectron microscopy. It also showed that, as compared with the flat surface, the density of Ti-OH groups on the NT surface has been increased. However, according to the contact angle goniometer, the hydrophilicity of the NT surface becomes worse than that of the flat surface. In addition, surface roughness was investigated by non-contact atomic force microscope. It demonstrated that the nano-roughness of NT arrays has been increased. More important is the relationship between contact angle and roughness factor have been analyzed based on the modified Young’s equation. These results indicate that the anodized NT structures may have provided an optimal surface roughness for promoting the bioactivity.

Abstract: A Type of Three-Dimensional Nano-Porous Film on Titanium Was Successfully Prepared by Alkali Treatment. the Microstructure, Contact Angle and Surface Energy of the Film Were Investigated Using Scanning Electron Microscopy (SEM) and Contact Angle Meter. the Biomineralization of the Nano-Porous Titanium Was Studied in Vitro by Soaking in Simulated Body Fluid (SBF). the Experiment Results Demonstrated that Bone-Like Apatite Could Be Induced on Nano-Porous Titanium Surface, and the Apatite Crystals on Nano-Porous Titanium Surface Were Superior in Number and Higher in Crystallinity to that on Titanium Chemically Polished.

Abstract: Nanobacteria is a tiny structure with size varying 80 to 500nm, commonly occurring in clusters and producing a biofilm which contains carbonate or hydroxyl apatite. In this study, the bioactive synthetic hydrogel materials were prepared with polyethylene glycol diacrylate (PEGDA) and 2-hydroxyethyl mathacrylate (HEMA) by UV photo-polymerization. Bone marrow mesenchymal stem cells (BMSCs) were seeded onto hydrogel surface for five days. The BMSCs cell adhesion on hydrogels was confirmed by SEM to evaluate the biocompatibility of the materials. It was found groups of nanoparticles on the hydrogel surface and the particles were analyzed by SEM. The particles were analyzed for its inorganic chemical constituents using energy dispersive X-ray microanalysis (EDS). The predominant components were found to be calcium (24.40%) and phosphorus (13.98%). The most likely source of cell culture contamination by such organisms is bovine serum albumin (BSA) used as supplement in culture media. Nanobacteria in BSA may be the important factor which accelerated hydroxyapatite crystal growth on hydrogels. It is important to study the biomineralization in biological system and has potential application in biomaterials science and biotechnology.

Abstract: In the present study, an Intelligent Multi-parameter Simulated Evaluation in vitro （IMSE system） was used to study the deposition properties of apatite formation on the surface of biphasic calcium phosphate porous ceramic (BCP) from static and dynamic r-SBF. Results showed that apatite formed on the surface of BCP from static and dynamic r-SBF differed between each other. In static r-SBF, ions were transferred by diffusion, which could not compensate the consuming of calcium ions, and mist apatite layer was formed on the surface of samples. But in the dynamic r-SBF, simulated fluid was adjusted precisely and flowed forcedly, the concentrations of ions were homogeneous; with the compensation of ions, calcium and phosphate were supersaturated, and the free energy of apatite formation was negative, bone-like apatite sheets were formed on the surface of samples.

Abstract: Papers reported that the pH value was rising slowly with the prolonging of soaking time when bioglass was studied into simulated body fluids, and it influenced the formation of apatite layer on the surface of bioglass obviously. An Intelligent Multi-parameter in vitro Simulated Evaluation （IMSE system） was used to study the bio-mineralization properties of 58S bioglass. The deposition of apatite formation on the surface of bioglass (BG) from dynamic r-SBF was studied systemically with IMSE system, which could control and stable such parameters as temperature, fluid rate, ion concentrations and pH value etc. precisely. Results showed that the rate of apatite formation was slowed down when pH value was stabled at about 7.35.

Abstract: The microstructure of scaffold was one of key factors for tissue engineering. Porous polycaprolactone (PCL) scaffolds were fabricated by combination of porogen-leaching and freeze-drying process. Ice particulates were used as porogen material, and PCL solutions in chloroform were mixed with ice particulates for 5minuture at zero temperature. Then the mixture was freezed in liquid nitrogen, and porous scaffold was prepared by freeze - drying finally. The microstructure and properties of the scaffolds were investigated. Porous structure of the scaffolds showed that good 3D microstructure and no porogen remained in the scaffold; pore size and porosity were determined by the size and mass fraction of ice particulates. The results demonstrated that the Scaffolds possessed open and interconnected pores with sizes ranging from several μm to more than 300μm and porosities of 50~80%.

Abstract: Porous bioactive thin film on commercially pure titanium substrate was prepared by micro-arc oxidation (MAO) in electrolytic solution, which contained calcium acetate, β-glycerol phosphate disodium salt pentahydrate (β-GP) and lanthanum nitrate. The phases and microstructure of the bioactive films were examined by X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectrometer and electron probe microanalysis. The results showed that: (1) porous bioactive films with about 10μm were formed on titanium substrate by MAO; (2) phases of the thin films were hydroxyapatite, anatase and rutile; (3) elements of Ca, P, and Ti of films were identified by EDS.

Abstract: In this study, biomemitic hydroxyapatite was prepared as a nano-sized powder from calcium nitrate tetrahydrate and diammonium hydrogen phosphate salts, but using the different contents of PVP modified hydroxyapatite and synthetic body fluid (SBF) solutions as synthesis medium instead of pure water at 37.4C and pH of 7.4. SBF was prepared in accord with the chemical analysis of human body fluid, with ion concentrations nearly equal to those of the inorganic constituents of human blood plasma. Characterization and chemical analaysis of the synthesized biomemitic hydroxyapatite powders and pure hydroxyapatite were investigated by X-ray powder diffraction, scanning electron microscopy, and inductively coupled plasma atomic emission spectroscopy. Rheological properties of HAP sol which reflected the interaction of hydroxyapatite particles were measured by R/S rheometer. The results showed that PVP evidently affected the stability and rheological properties of HAP sol, and PVP were based on the different mechanism at different concentrations. PVP was operating as an interparticle bridging reagent at low concentrations(0.5%), while it acted as an dispersant at high concentrations(2.0%). The biomemitic hydroxyapatite with the sizes of 10~30nm was spherical and poor crystalline, which was synthesized in synthetic body fluid (SBF) by addition of 2.0% PVP.

Abstract: In the present study, bioactive functional gradient coatings were prepared using net-energy controlled plasma spraying technology. The microstructure and phases of the bioactive functional gradient coating were examined by means of transmission electron microscope, scanning electron microscopy and X-ray diffraction. The results revealed that: (1) as-sprayed coatings contained a large amount of amorphous phases and some nano-sized HA crystals formed during rapid solidification, (2) surface of the coating was very rough with different-sized micropores, and the gradient layer was much denser which firmly bonded to the substrate without gaps and obvious interface between the coating and the substrate

Abstract: In this article, a multilayer tissue engineering scaffold has been fabricated. The uppermost layer is consisted by the collagen and the downmost layer is consisted by the collagen/hydroxyapatide. Between the two layers, there have several continues changed collagen/HA layers at different ratio. These gradient scaffolds have been made by the freeze dried method. The morphology of the multiphase scaffold has been observed by the SEM. The chondrocytes from New Zealand rabbit knee joint were separated, harvested and cultured on the top layer of the scaffold. The histological and the immunohistochemical testing show that the chondrocytes keep its normal type in the 2 culture weeks.