Evaluation of the bonding behaviour of thin bio‐based wooden laminates

Thermoplastic laminates usually consist of oriented fibres in thermoplastic matrices. Commonly glass fibres or carbon fibres are used as reinforcement for such laminates. The application of thin wooden sheets (veneers) as reinforcement applications is new. Therefore the bonding of such combinations has to be investigated. Various tests can be used for evaluating the bonding between the components of the laminates. The aim of this study is to determine a fast and easy method suitable for quality control of new bio‐based wooden laminates.     

Hierarchically Inverse Opal Porous Scaffolds from Droplet Microfluidics for Biomimetic 3D Cell Co-Culture

With the advantages of better mimicking the specificity of natural tissues, three-dimensional (3D) cell culture plays a major role in drug development, toxicity testing, and tissue engineering. However, existing scaffolds or microcarriers for 3D cell culture are often limited in size and show suboptimal performance in simulating the vascular complexes of living organisms. Therefore, we present a novel hierarchically inverse opal porous scaffold made via a simple microfluidic approach for promoting 3D cell co-culture techniques. The designed scaffold is constructed using a combined concept involving an emulsion droplet template and inert polymer polymerization. This work demonstrates that the resultant scaffolds ensure a sufficient supply of nutrients during cell culture, so as to achieve large-volume cell culture. In addition, by serially planting different cells in the scaffold, a 3D co-culture system of endothelial-cell-encapsulated hepatocytes can be developed for constructing certain functional tissues. It is also demonstrated that the use of the proposed scaffold for a co-culture system helps hepatocytes to maintain specific in vivo functions. These hierarchically inverse opal scaffolds lay the foundation for 3D cell culture and even the construction of biomimetic tissues.     

聚酰胺-66/羟基磷灰石复合材料的制备和性能研究

本文通过溶液法制备了一系列聚酰胺 66/羟基磷灰石复合材料。用IR ,TGA和燃烧实验对复合材料的结构和组成进行了表征 ,并对复合材料的热稳定性 ,力学性能和生物安全性及生物活性进行了初步研究。结果表明所制备的聚酰胺 66/羟基磷灰石复合材料 ,组成均一 ,具有良好的热稳定性和力学性能 ,良好的生物安全性和生物活性 ,可能作一种新的骨修复材料 ,在生物医学材料的研究中具有重要意义     

Composite beads of alginate and biological hydroxyapatite from poultry and mariculture for hard tissue repair

Synthesizing materials that stimulate the natural growth of living tissues and restore damaged parts of the body is one of the most challenging problems in regenerative medicine. Despite being the most commonly used biomaterial, synthetic hydroxyapatite is a calcium phosphate with a relatively low rate of bioresorption related to new tissue growth. For specific applications, the speed of resorption is essential, and synergy between polymer and hydroxyapatite composite materials from natural sources can be developed. Therefore, this study attempts to synthesize hydroxyapatite from poultry and mariculture by-products and produce spheres with alginate for use as biomaterials for tissue repair. Shells different shellfish and eggs were used as sources of CaCO₃ and added to a phosphoric acid solution as precursors in wet synthesis. The powders were dried, thermally treated and characterized. Structural analysis revealed hydroxyapatite in nanometric crystallites (61–72 nm) with high crystallinity (86–89%). The calcium phosphate obtained from Mozambique shellfish acquired the best characteristics. Beads with various sizes and porosities were produced through changes in the process parameters, including the type and size of the dripper, speed of agitation of the solution, and type of drying. The results show that the type of dripper strongly influences the size of the beads and that the rotation speed influences the sphericity. The styling directly influenced the fluid absorption, demonstrating that the spheres dried by lyophilization can absorb up to 223% of their weight. In comparison, samples dried in a desiccator could absorb only 112% of their weight in body fluids. The porosity of the optimized beads was up to 90%, which is similar to that of human bone, and they did not show cytotoxicity. Therefore, the beads composed of alginate and hydroxyapatite produced here have the potential for application in tissue repair.     

Corrosion of biomaterials: anodic treatment and evaluation of 316L stainless steel in simulated body fluid

The influence of electropolishing at different conditions on the electrochemical behaviour of 316L stainless steel (316L SS) in simulated body fluid (SBF) was investigated. Accordingly, 316L SS samples were electropolished in several electropolishing baths of H₃PO₄ and H₂SO₄ at 2–6 applied volts and 50–110°C for different time intervals. The corrosion behaviour then was studied by means of potentiodynamic polarisation technique and electrochemical impedance spectroscopy in SBF at 37°C. The surface morphology was also investigated by scanning electron microscopy. The results proved that the treated samples had better corrosion resistance than nonpolished one. The highest corrosion resistance was observed for the treated sample at 5?V and 90°C in 10:90 ratio of acidic electrolyte (H₃PO₄:H₂SO₄) for 15?min. Moreover, the corrosion resistances of anodically treated samples were found to be dependent greatly on applied volt, bath temperature, polishing time and phosphoric to sulphuric acids ratio.     

Study of the corrosion resistance and in vitro biocompatibility of PVD TiCN-coated AISI 316 L austenitic stainless steel for orthopedic applications

The aim of the present work was to study the corrosion resistance in Hanks' solution and the in vitro biocompatibility of a TiCN-coated AISI 316 L stainless steel. The electrochemical behavior was assessed using potentiodynamic polarization and electrochemical impedance spectroscopy. Cytotoxicity and genotoxicity tests were performed to evaluate the potential biocompatibility of the specimens. TiCN morphology was investigated using scanning electron microscopy (SEM). Bare 316 L specimens were also evaluated for comparison. The results showed that the film morphology strongly influences the electrochemical behavior of the coated underlying metal. TiCN-coated specimens presented neither cytotoxicity nor genotoxicity.     

Functional Materials for Bone Regeneration from Beta‐Tricalcium Phosphate

Biodegradable ceramics of β‐tricalcium phosphate (β‐TCP, Ca₃(PO₄)₂) are widely used as bone regeneration materials. The goal is a complete regeneration of the bony defect (restitutio ad integrum = full recovery). Different bioceramics made of β‐TCP show fundamental differences in terms of phase purity, primary particle size, stability, porosity, solubility and therefore biodegradation of the material. Cerasorb® is a bioceramic consisting of phase pure β‐TCP. The primary particle size in connection with a stable sinter structure forms a porous biomaterial which is optimised in the functional surface, porosity and resorption/degradation behaviour. Different forms of Cerasorb® are available: granular materials with high and low porosity optimised for specific indications as well as block forms shapeable by the surgeon for various bony defects.     

蚕丝丝素蛋白材料的生物降解性能研究进展

丝素蛋白具有良好的生物相容性,但其用于制备组织工程支架等生物材料时,制成的材料还需具备的一个重要条件是其降解速率与组织新生的速率相匹配。近年来国内外对丝素蛋白材料生物降解性能的研究进展表明,影响材料降解性能的因素包括材料的形态、结构、植入点的机械和生理环境等。这些参数影响降解行为的具体过程和机理将是今后的研究重点。     

New families of mesoporous materials

Abstract

Mesoporous materials have been paid much attention in both scientific researches and practical applications. In this review, we focus on recent developments on preparation and functionalization of new families of mesoporous materials, especially non-siliceous mesoporous materials invented in our research group. Replica synthesis is known as the method to synthesize mesoporous materials composed of various elements using originally prepared mesoporous replica. This strategy has been applied for the syntheses of novel mesoporous materials such as carbon nanocage and mesoporous carbon nitride. Carbon nanocage has a cage-type structure with huge surface area and pore volume, which exhibits superior capabilities for biomolecular adsorption. Mesoporous carbon nitride was synthesized, for first time, by using mixed material source of carbon and nitrogen simultaneously. As a totally new strategy for synthesis of mesoporous materials, the elemental substitution method has been recently proposed by us. Direct substitution of component elements in original mesoporous materials, with maintaining structural regularity, provided novel mesoporous materials. According to this synthetic strategy, mesoporous boron nitride and mesoporous boron carbon nitride have been successfully prepared, for first time. In addition to these material inventions, hybridization of high functional materials, such as biomaterials, to mesoporous structure has been also developed. Especially, immobilization of proteins in mesopores was systematically researched, and preparation of peptidehybridized mesoporous silica was demonstrated. These new families of mesoporous materials introduced in this review would have high potentials in future practical applications in wide ranges from electronics and photonics to environmental and medical uses.     

HA／ZrO2功能梯度涂层中羟基磷灰石的超微结构分析

利用净能量控制的PRAXAIR 4500型等离子喷涂系统，在钛合金基体上制备出HA／ZrO2功能梯度涂层，采用HTEM、XRD、SEM和表面轮廓仪等对涂层表面HA的显微结构和相结构特征进行分析。结果表明：（1）喷涂态涂层表面HA主要以非晶相存在，存在微量的纳米HA晶体；（2）大气气氛700℃晶化处理显著提高涂层表面HA结晶度，涂层以结晶的HA相存在，且晶体结构完整；（3）HA／ZrO2功能梯度涂层表面粗糙多孔，呈现“二级窝洞”的形貌特征，有利于材料与骨组织间的结合。