Chunyong Liang

Biological properties of nanostructured Ti incorporated with Ca, P and Ag by electrochemical method

TiO2 nanotube arrays were synthesized on Ti surface by anodic oxidation. The elements of Ca and P were simultaneously incorporated during nanotubes growth in SBF electrolyte, and then Ag was introduced to nanotube arrays by cathodic deposition, which endowed the good osseointegration and antibacterial property of Ti. The bioactivity of the Ti surface was evaluated by simulated body fluid soaking test. The biocompatibility was investigated by in vitro cell culture test. And the antibacterial effect against Staphylococcus aureus was examined by the bacterial counting method. The results showed that the incorporation of Ca, P and Ag elements had no significant influence on the formation of nanotube arrays on Ti surface during electrochemical treatment. Compared to the polished or nanotubular Ti surface, TiO2 nanotube arrays incorporated with Ca, P and Ag increased the formation of bone-like apatite in simulated body fluid, enhanced cell adhesion and proliferation, and inhibited the bacterial growth. Based on these results, it can be concluded that the nanostructured Ti incorporated with Ca, P and Ag by electrochemical method has promising applications as implant material.

Preparation of Hydrophobic and Oleophilic Surface of 316 L Stainless Steel by Femtosecond Laser Irradiation in Water

An excellent hydrophobic and super-oleophilic surface on 316 L stainless steel was obtained by femtosecond laser irradiation in deionized water. Using lower laser fluence and scanning speed of femtosecond laser irradiation, a single stripe structure was fabricated and the corresponding contact angle to water and ethylene glycol was 127.2° and 19.6°, respectively. When laser fluence and scanning speeds increased, stripes, grooves, and holes structures were obtained on the surface and the corresponding water contact angles increased and ethylene glycol contact angles decreased, with a maximum water contact angle of 142.5° and minimum ethylene glycol contact angle of 6.4°.

Biological and Mechanical Effects of Micro-Nanostructured Titanium Surface on an Osteoblastic Cell Line In vitro and Osteointegration In vivo

Hybrid micro-nanostructure implant surface was produced on titanium (Ti) surface by acid etching and anodic oxidation to improve the biological and mechanical properties. The biological properties of the micro-nanostructure were investigated by simulated body fluid (SBF) soaking test and MC3T3-E1 cell co-culture experiment. The cell proliferation, spreading, and bone sialoprotein (BSP) gene expression were examined by MTT, SEM, and reverse transcription-polymerase chain reaction (RT-PCR), respectively. In addition, the mechanical properties were evaluated by instrumented nanoindentation test and friction-wear test. Furthermore, the effect of the micro-nanostructure surface on implant osteointegration was examined by in vivo experiment. The results showed that the formation of bone-like apatite was accelerated on the micro-nanostructured Ti surface after immersion in simulated body fluid, and the proliferation, spreading, and BSP gene expression of the MC3T3-E1 cells were also upregulated on the modified surface. The micro-nanostructured Ti surface displayed decreased friction coefficient, stiffness value, and Young’s modulus which were much closer to those of the cortical bone, compared to the polished Ti surface. This suggested much better mechanical match to the surrounding bone tissue of the micro-nanostructured Ti surface. Furthermore, the in vivo animal experiment showed that after implantation in the rat femora, the micro-nanostructure surface displayed higher bonding strength between bone tissues and implant; hematoxylin and eosin (H&E) staining suggested that much compact osteoid tissue was observed at the interface of Micro-nano-Ti-bone than polished Ti-bone interface after implantation. Based on these results mentioned above, it was concluded that the improved biological and mechanical properties of the micro-nanostructure endowed Ti surface with good biocompatibility and better osteointegration, implying the enlarged application of the micro-nanostructure surface Ti implants in future.

Surface Roughness and Hydrophilicity of Titanium after Anodic Oxidation

Abstract Anodic oxidation was applied to prepare the nanostructured titanium surface with different roughnesses and hydrophilicities. The morphology was characterized by scanning electron microscopy (SEM). The surface roughness was tested by atomic force microscopy (AFM), and the hydrophilicity was assessed from the contact angle between the deionized water and sample surface at room temperature. The results show that surface morphologies change remarkably with applied voltage and oxidation time during anodic oxidation. Under optimized oxidation conditions, well-ordered nanotube arrays were fabricated on the Ti surface. Roughness values increase with increase of the oxidation time, ranging from several dozen to several hundred nanometers, while the influence of voltage on surface roughness is not obvious. The hydrophilicity increases initially with the increase of oxidation time, but then decrease. The variations of surface morphology, roughness and hydrophilicity are correlated to the reactions occurring during the anodic oxidation.

Corrosion resistance and biological properties of a micro–nano structured Ti surface consisting of TiO2 and hydroxyapatite

A micro–nano structured titanium (Ti) surface consisting of titania (TiO2) and hydroxyapatite (HA) was produced by one-step micro-arc oxidation (MAO) to improve the corrosion resistance and biological properties. The corrosion resistance was evaluated in simulated body fluids (SBF) by electrochemical impedance spectroscopy (EIS) and anodic polarisation tests. The biological properties were investigated by in vitro cell co-culture experiments and in vivo experiments. The results showed that a microstructured TiO2 coating loaded with a nanostructured HA slice could be obtained on the Ti substrate during the MAO process. The MAO induced composite coating showed an increased resistance value and corrosion potential. It also promoted the cell behaviors (proliferation and spreading) on the Ti surface. After implantation in the rat tibias, the bonding strength between the bone tissues and implant was enhanced. The improved corrosion resistance was attributed to the increased thickness of the oxide layer, and the enhanced biological properties resulted from the micro–nanostructure and HA on the Ti surface. Based on these results, it was concluded that the micro–nano structured Ti surface consisting of TiO2 and HA prepared by MAO has great potential to be applied in the clinic.

Carbon nanotube-reinforced mesoporous hydroxyapatite composites with excellent mechanical and biological properties for bone replacement material application

Carbon nanotube (CNT)-reinforced mesoporous hydroxyapatite (HA) composites with excellent mechanical and biological properties were fabricated successfully by the in situ chemical deposition of mesoporous HA on homogeneously dispersed CNTs. The CNTs are first synthesized in situ on HA nanopowders by chemical vapor deposition, and then, the HA particles with mesoporous structures are deposited in situ onto the as-grown CNTs by using cetyl trimethyl ammonium bromide as templates to form mesoporous HA encapsulated CNTs (CNT@meso-HA). The modification of CNTs by mesoporous HA leads to strong CNT-HA interfacial bonding, resulting in efficient load transfer between CNT and HA and improved mechanical properties of CNT/HA composites. More importantly, the mesoporous HA structure has a high specific surface area and large surface roughness that greatly promote the cell adhesion and proliferation, resulting in better biocompatibility and improved osteoblast viability (MC3T3-E1) compared to those fabricated by traditional methods. Therefore, the obtained CNT@meso-HA composites are expected to be promising materials for bone regeneration and implantation applications.

Highly efficient light trapping of metallic microstructures induced by femtosecond lasers

Microstructuring of NiTi alloy plates by 800 nm femtosecond lasers is investigated through the line-scribing experiment in ambient air. It is found that some distinct surface structures can be generated by varying laser pulse energies and the scan speeds of the samples. Very weak stray light is detected when He-Ne laser beam is directed on the micro-structured targets. The integrated reflectance measurements reveal that the light trapping of these structured metal surfaces can be improved greatly, even up to 90%, within a large spectral range covering the ultraviolet, the visible and the mid-infrared. It is expected that this result could have great potential applications in the designing of efficient energy transfer devices.