Multifunctional Composites of Ceramics and Single‐Walled Carbon Nanotubes

Polycrystalline ceramic/single‐walled carbon nanotube (SWNT) composites possess unique grain boundaries, containing 1D tortuous SWNTs bundles that form 2D tangled embedded nets. This unprecedented grain‐boundary structure allows tailoring of multifunctional ceramic/SWNTs composites with unique combinations of desirable mechanical (toughness, strength, creep) and transport (electrical, thermal) properties. A brief discussion and analysis of recent developments in these composites are presented.     

Synthesis,Structure, and Properties of Single‐Walled Carbon Nanotubes

Great interest in single‐walled carbon nanotubes (SWCNTs) derives from their remarkable electrical, thermal, optical, and mechanical properties together with their lower density, which promise extensive and unique applications. Much progress has been achieved in the fundamental and applied investigations of SWCNTs over the past decade. At the same time, many obstacles still remain, hampering further development in this field. To clarify the emerging problems and to provide a comprehensive understanding of the field, we review the recent progress of research on the synthesis, structure, and properties of SWCNTs, in particular the SWCNT non‐woven film, SWCNT rings, boron–nitrogen (B–N) co‐doped SWCNTs (BCN‐SWNTs), and individual SWCNTs. Some long‐standing problems and topics warranting further investigations in the near future are addressed.     

Growth of Single‐Walled Carbon Nanotubes from Sharp Metal Tips

The nucleation and growth of single‐walled carbon nanotubes is observed in situ in a transmission electron microscope. Carbon atoms are implanted into catalytically active metal particles by electron‐beam sputtering. The metal particles are then shaped with a focused electron beam. Once the particles have a region of high surface curvature, spontaneous nucleation and growth of single‐walled carbon nanotubes occurs on the metal particles. It is shown that the local solubility of carbon in the metal determines the nucleation of nanotubes. This is confirmed by atomistic computer simulations treating the solubility of carbon in a metal particle as a function of the size of the system.     

Structure‐Dependent Mitochondrial Dysfunction and Hypoxia Induced with Single‐Walled Carbon Nanotubes

Cytotoxicity of nanomaterials on living systems is known to be affected by their size, shape, surface chemistry, and other physicochemical properties. Exposure to a well‐characterized subpopulation of specific nanomaterials is therefore desired to reveal more detailed mechanisms. This study develops scalable density gradient ultracentrifugation sorting of highly dispersed single‐walled carbon nanotubes (SWNTs) into four distinct bands based on diameter, aggregation, and structural integrity, with greatly improved efficiency, yield, and reproducibility. With guarantee of high yield and stability of four SWNT fractions, it is possible for the first time, to investigate the structure‐dependent bioeffects of four SWNT fractions. it is possible Among these, singly‐dispersed integral SWNTs show no significant effects on the mitochondrial functions and hypoxia. The aggregated integral SWNTs show more significant effects on the mitochondrial dysfunction and hypoxia compared to the aggregated SWNTs with poor structure integrity. Then, it is found that the aggregated integral SWNTs induced the irregular mitochondria respiratory and pro‐apoptotic proteins activation, while aggregated SWNTs with poor structure integrity greatly enhanced reactive oxygen species (ROS) levels. This work supports the view that control of the distinct structure characteristics of SWNTs helps establish clearer structure‐bioeffect correlation and health risk assessment. It is also hoped that these results can help in the design of nanomaterials with higher efficiency and accuracy in subcellular translocation.