In-situ formed graded microporous structure in titanium alloys and its effect on the mechanical properties

A simple method to fabricate porous titanium was developed, with which the graded microporous titanium alloys could be prepared by simply casting. The in-situ formed graded microporous structure and its effect on the mechanical properties of the titanium alloys were investigated. The results indicated that the mechanical properties of such graded microporous titanium alloys were superior to the porous titanium fabricated by other methods. This work provides a bright prospect for the production of graded porous titanium alloys with low-cost and high properties. This method can also be applied to synthesize other porous metallic biomaterials.     

Functionalization of Ti6Al4V scaffolds produced by direct metal laser for biomedical applications

Direct metal laser sintering (DMLS) is a powerful tool to produce titanium based biomaterials because the ease to convert 3D medical imaging data into solid objects with excellent mechanical and corrosion properties. DMLS samples can be functionalized by anodizing, allowing the growth of titanium oxide layers of enhanced properties. In the present paper, a complete characterization of the microstructure, mechanical properties and particularly, the corrosion behavior has been carried out to assess their possible use as biomaterial. The results of the anodized scaffolds are very promising, showing a Young Modulus near to the cortical bone and a low corrosion rate, ensuring their suitability for medical applications.     

Fabrication and Characterization of Nanopillar-Like HA Coating on Porous Ti6Al4V Scaffold by a Combination of Alkali–Acid-Heat and Hydrothermal Treatments

Porous titanium scaffold with suitable porous architecture exhibits enormous potentials for bone defect repairs. However,insufficient osteointegration and osteoinduction still remain to open as one of the major problems to achieve satisfactory therapeutic effect. To solve this problem, many studies have been carried out to improve the bioactivity of porous titanium scaff old by surface modifications. In this study, porous Ti6Al4V scaff olds were fabricated using additive manufacturing technique. Porous architectures were built up based on a diamond pore structure unit. Alkali–acid-heat(AH) treatment was applied to create a TiO_2 layer on the porous Ti6Al4V scaff old(AH-porous Ti6Al4V). Subsequently, a hydrothermal treatment was employed to enable the formation of HA coating with nanopillar-like morphology on the alkali–acid-heat-treated surface(HT/AH-porous Ti6Al4V). The effects of surface modifications on apatite-forming ability, protein adsorption,cell attachment, cell proliferation and osteogenic gene expression were studied using apatite-forming ability test, protein adsorption assay and in vitro cell culture assay. It was found that the HT/AH-porous Ti6Al4V exhibited the highest apatite formation ability and best affinity to fibronectin and vitronectin. In vitro studies indicated that the mesenchymal stem cells(MSCs) cultured on the HT/AH-porous Ti6Al4V presented improved adhesion and differentiation compared with the porous Ti6Al4V and AH-porous Ti6Al4V.     

Processing and mechanical properties of hydroxyapatite–polysulfone laminated composites

Designing biocomposites that mimic bone with specific mechanical properties of toughness and elastic modulus is a long-standing challenge in the biomaterials field. Traditional biocomposites comprise polymer matrices reinforced with ceramic particles. Laminated composites are structures also found in nature that can offer improved mechanical properties such as strength, elastic modulus and toughness. Hydroxyapatite/polysulfone laminated composites were fabricated to develop biologically compatible, toughened composites that would match the elastic modulus of bone. Multilayered composites were successfully designed with improved toughness measured by the work of fracture. Toughness measurements were more than an order of magnitude greater than monolithic hydroxyapatite. The toughness and modulus values of hydroxyapatite/polysulfone were within the range of cortical bone.     

Prilling process applied to collagen solutions

Abstract

The present work concerns the preparation of microbeads of collagen by a prilling process.

Collagen is one of the main components of vertebrate proteins, especially in. such tissues as skin, tendons, placenta, … Furthermore, it has some properties which makes it interesting to use as a biomaterial: biocompatibility, biodegradability, high tensile strength, hemostatic power, participation to the wound healing.

The patented process which is developped in this paper combines two techniques :

? breaking of a capillary flow by prilling

and

? reticulation of collagen after oxydation with periodic acid.

It uses neither organic solvents, nor variation of temperature and allows the production of microbeads which can be utilized for many different medical applications.     

Synthesis and in vitro bioactivity of novel mesoporous hollow bioactive glass microspheres

The remarkable tissue-repairing bioactivity and biocompatibility of bioactive glass make it suitable for a wide range of applications. Here, novel mesoporous hollow bioactive glass microspheres (MHBGMs) with a uniform diameter range of 2-5 µm were prepared by a sol-gel method. Structural characterization indicated that the shell of hollow sphere had a mesopore size range between 2 and 10 nm and a thickness about 500 nm. The in vitro bioactivity test indicated that the novel structure exhibited high in vitro bioactivity. The uniform microspherical morphology and mesoporous hollow structure of MHBGMs, together with their high bioactivity, turn them into a good candidate as an injectable and drug-loading biomaterial for in vivo tissue regeneration and drug control release.     

Microstructures and friction-wear characteristics of bivalve shells

All structural biological materials are nearly composite materials and often exhibit some superior properties. In order to obtain useful information for the design and manufacture of composite materials, the microstructures and the friction-wear properties of three species of bivalve shells were studied in this paper. The results showed that the microstructure of tested bivalve shells I (Meretrix meretrix) and II (Saxidomus purpuratus) are constructed of about 10–100 μm small platelets stacked in brick-and-mortar fashion and small platelets consist of lamella clusters. The lamellae are parallel inside the individual cluster. The orientations of adjacent lamellae clusters form the angle of about 70–90°. The thickness of lamellae is about about 0.2–0.6 μm. The organic component and the calcium carbonate form the three-dimensional net-like microstructure, respectively, which interlaces each other to form the microstructure of the bivalve shells. The microstructure of bivalve shells III (Periglypta chemnitzii) is constructed of about 10–40 μm particles with the internal structure of lamellae clusters as the above mentioned. Under the experimental conditions of medium-carbon steel counterpart and sliding dry friction, the friction coefficient of the bivalve shells is lower than that of grey cast iron HT200. The organic component of the bivalve shells can transfer to the friction interface and form organic film, which not only lubricates the friction interface but also protects the friction surface. The organic component is very important to the friction-wear property of the shells.     

Effect of pH on the precipitation of hydroxyapatite on silica gels

Silica-HAp composites have been produced with particle size ranging from several nm to few μm, through control of the pH of the solution, which also controls morphology. A calcium ions reservoir has been made available as a Ca/EDTA soluble complex allowing the production of HAp at low temperature and short periods of time (hours). The presence of silica seems to promote the formation of HAp under these conditions. Electronic Publication     

Synthesis and in vitro bioactivity of a borate-based bioglass

A bioactive borate glass was synthesized through normal melting-derived route in this letter. The degradation and bioactivity of the glass were studied by the immersion of glass microspheres in a dilute K₂HPO₄ solution. The cell growth inhibition rate of the borate glass was examined by MTT assay. The conversion product of the borate glass was identified by XRD, SEM. It was confirmed that the borate glass had a rapid degradation rate, comparing with the silicate-based bioglass, 45S5 glass. HA formed from the borate glass, that is an indication of bioactive potential in vivo. MTT assay results demonstrate that the inhibition effect of B ions released from the borate glass on cell proliferation can be alleviated by diluting extract solution to a certain concentration (v/v ratio: 1:4, [B] < 1.792 mM). It is believed that the borate glass could be a desirable biomaterial for preparing scaffold of tissue engineering.