骨和牙中磷酸钙的矿化过程及其模拟的研究进展

磷酸钙是生物体中的主要矿化物.本文综述了骨和牙中磷酸钙的矿化过程及其体外模拟的研究进展,比较了两者在成分、结构、有机基质和形成机理等方面的异同.从分子识别、晶格匹配、静电作用等方面讨论了矿化过程中有机基质对磷酸钙晶体生长的调制作用.     

The effect of pore morphology and agarose coating on mechanical properties of tricalcium phosphate scaffolds

Three-dimensional biocompatible porous structures can be fabricated using different methods. However, the biological and mechanical behaviors of scaffolds are the center of focus in bone tissue engineering. In this study, tricalcium phosphate scaffolds with similar porosity contents but different pore morphologies were fabricated using two different techniques, namely, the replica method and the pore-forming agent method. The samples fabricated using the pore-forming agent showed more than two times higher compressive and bending strengths and more than three times higher compressive moduli. Furthermore, a thin layer of agarose coating improved the compressive and bending strength of both types of ceramic scaffolds. Subsequently, the samples’ capability to guide biomineralization was evaluated by immersion into a simulated body fluid that developed Ca-P nano-platelets formation and enhanced the compressive strength. Finally, the tetrazolium-based colorimetric (MTT) assay was used to evaluate L929 cell viability and proliferation on all the samples and confirmed that cell behavior was not affected by pore morphology or agarose coating. In summary, samples produced by the use of the pore-forming agent showed higher potential to be applied as bone scaffolds in tissue engineering applications.     

微生物矿化作用抑制金属腐蚀行为的研究进展

概述了微生物矿化的基本过程,并总结阐述了常见诱导矿化作用的微生物类型及矿化产物类型,总结并举例说明了影响微生物矿化作用的主要因素.在此基础上,重点综述了微生物诱导矿化形成的矿化层类型,主要包括碳酸钙矿化层、磷酸钙矿化层、铁氧化物矿化层,并举例阐述了不同矿化过程之间的差异与形成的各类矿化层的特点.根据近年来微生物矿化作用在抑制金属腐蚀方面的研究进展,分别从微生物呼吸过程中耗氧过程和矿化层的屏蔽作用两方面阐述了微生物矿化作用抑制金属腐蚀的主要原因.最后,结合微生物矿化作用的常见环境,展望了微生物矿化作用在抑制金属腐蚀手段方面的发展方向.     

Innovative collagen nano-hydroxyapatite scaffolds offer a highly efficient non-viral gene delivery platform for stem cell-mediated bone formation

The ability of nano-hydroxyapatite (nHA) particles developed in-house to act as non-viral delivery vectors is assessed. These nHA particles are combined with collagen to yield bioactive, biodegradable collagen nano-hydroxyapatite (coll-nHA) scaffolds. Their ability to act as gene-activated matrices for BMP2 delivery is demonstrated with successful transfection of mesenchymal stem cells (MSCs) resulting in high calcium production.     

Silica pattern formation in diatoms: species-specific polyamine biosynthesis

Diatoms are eukaryotic, unicellular algae that are well known for the intricate architecture of their silica-based cell walls. Species identification is mainly based on variations of their hierarchically organized silica structures. Particularly striking silica frameworks are found among diatoms that belong to the genus Coscinodiscus. Recent work indicates an important role for long-chain polyamines in guiding silica precipitation as well as in silica-pattern formation. Here we demonstrate that polyamines, even if isolated from closely related diatom species, exhibit substantial structural differences. Structural variations include the overall chain length, the degree of methylation, positions of secondary amino functionalities, and, unexpectedly, site-specific incorporation of a quaternary ammonium functionality. These findings support a specific role for polyamines in creating silica nanostructures.