Cover Picture: Novel Photoactive Single‐Walled Carbon Nanotube–Porphyrin Polymer Wraps: Efficient and Long‐Lived Intracomplex Charge Separation (Adv. Mater. 7/2005)

The figure on the cover portrays a novel donor–acceptor nanoassembly, based on a single‐walled carbon nanotube (SWNT) as the electron acceptor and poly(methyl methacrylate) (PMMA)‐carrying porphyrin units (H2P) as the excited‐state electron donors. In these supramolecular “polymer wraps”, reported on p. 871 by Guldi and co‐workers, SWNTs quench the photoexcited H2P chromophores, resulting in the creation of microsecond‐lived radical ion pairs.     

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.     

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.     

Cover Picture: Effect of Water Filling on the Electronic and Vibrational Resonances of Carbon Nanotubes: Characterizing Tube Opening by Raman Spectroscopy (Adv. Mater. 17/2007)

Closed (empty) and opened (water‐filled) single‐walled carbon nanotubes (SWNTs), such as the (12,1) SWNTs shown (foreground), can be clearly resolved in 2D Raman maps (background) of bile salt solubilized SWNTs in water, report Wim Wenseleers and co‐workers on p. 2274. While being of fundamental interest, this also provides a method to monitor tube opening/closing under various treatments (insets, left to right: as‐produced; mechanically treated; chemically treated; reclosed SWNTs by annealing).