Cheng Yun Ning

Bone-Like Apatite Formation on Modified PCL Surfaces under Different Conditions

The PCL plates hydrolyzed by NaOH aqueous solutions and carboxylate groups were introduced onto the surfaces of specimen. Specimens were treated by CaCl2 and K2HPO4⋅3H2O under the normal-pressure condition and low-pressure of 103 Pa condition for 30min separately. Dense and uniform bone-like layers could be formed on the surface of specimens after mineralizing for less than 24h in simulated body fluids (SBF). The low-pressure condition could accelerate the formation of apatite layer.

Effect of Different Acid Treatment on Surface Characteristics of Titanium Alloy

This study was aimed to investigate the effects of acid treatment on the surfacee characteristics ofgrit-blasted titanium alloy (Ti6Al4V). These treatments included (a) Al2O3 blasting, (b) Al2O3 blasting + HF acid etching, (c) Al2O3 blasting + HCl/H2SO4 acid etching, and (d) Al2O3 blasting + HF acid etching + HCl/H2SO4 acid etching. The surface topography and chemical composition of the samples were identified by field-emission scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. Roughness of the as-treated samples was obtained from atomic force microscopy (AFM) and profilometry. Wettability of the samples was measured using sessile drop method. The results showed that porous structure on the surface of titanium alloy was prepared by dual acid etching treatment and the surfaces treated with acid had higher roughness and better wettability than the surface treated only by grit-blasting.

Influence of pH Value Stability on the Biomineralization of Bioglass

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.

Application of Multilayer Collagen/HA Scaffold in Cartilage Tissue Engineering

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.

Characteristics of TiO2 Nanotube Arrays on Titanium Prepared by Anodization

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.

Study on Surface Characterization and Properties of Three Dimensional Nano-Porous Titanium Film

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.

Fabrication and Characterization of Bioactive Composite Scaffolds Based on β-TCP-BG-PLA for Bone Tissue Engineering

In this study, the bioactive composites based on β-tricalcium phosphate (β-TCP), bioglass (BG) and poly lactic acid (PLA) were prepared. The microstructure, degradability and reaction products of the scaffold soaked in a simulated body fluid (SBF) at 36.5°C for different days were characterized through scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDS), X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR) and induced coupled plasma spectroscopy (ICP). The weight loss and strength decrease with the time were tested. The results showed that at the same porosity, the degradability of the scaffold samples decreased as followed: β-TCP/BG/PLA>β－TCP/BG>β－TCP.The materials had highly bioactive response ability to the Simulate Body Fluid (SBF) and promptly induced a bone like HA layer on the surface of the scaffolds when immersed in the SBF.

Microstructure and Mechanical Performances of Plasma-Sprayed Functionally Gradient HA-ZrO2-Bioglass Coatings

For practical applications such as artifical joints and dental implants, there is a strong demand for hydroxyapatite coatings with excellent performances to ensure long-term fixation. In the present study, functionally gradient HA-ZrO2-Bioglass coatings were prepared using net-energy controlled plasma spraying technology. The structural characteristics andmechanical performances of the coatings were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD) and nanoindentation. The results showed that: (1) Pore sizes and compositions of the coatings changed gradually along the vertical substrate, crystal HA with few calcium phosphates was presented in the heat-treated coatings. (2) Surface of the coating was very rough with nano-sized crystalline grains and micropores; (3) Young’s modulus and hardness changed gradually at the range of coating-Ti6Alo4V interface. Compared with HA coatings, the tensile adhesive strength of the functionally graded HA-ZrO2-Bioglass coatings reached 38.6 MPa, much higher than that of single HA coatings.

Study of Bio-Mineralization of BCP with Compensation of Calcium and Phosphate Ions

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.

Preparation of Porous Polycaprolactone Scaffolds by Using Freeze-Drying Combined Porogen-Leaching Methods

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%.