Thin film networks of multiwalled carbon nanotubes (MWCNTs) were prepared by exerting chemically induced capillary forces upon the nanotubes. During this process MWCNTs undergo a transformation from being a vertically aligned structure to an interlocking resistive network of interconnected nanotubes, whose main feature is a regular three-dimensional (3D) sieve architecture. Due to their structural characteristics at the nanoscale level, 3D-MWCNT-based networks are in principle ideal candidates for scaffolds/matrices in tissue engineering. Their potential application in this field was confirmed by extensive growth, spreading, and adhesion of the common mouse fibroblast cell line L929.

A novel method was developed to electroporate gram-negative bacteria (Acidothiobacillus ferrooxidans) via multiwall carbon nanotubes (CNTs). CNTs are metallic, ultra strong nanofibers of ∼10 nm in diameter and many microns long. When placed in an electric field, the CNTs strongly enhance the electric field at their ends by a factor of 10−100, making them ideal for localized electroporation. Addition of CNTs into a solution containing bacteria and gold nanoparticles (GNPs) and subsequent exposure to microwave radiation facilitates a rapid transport of GNPs across the cell wall, without affecting the cell viability.

Introduction of foreign genes into bacterial cells (transformation) is used for supplementing defective genes or providing additional biological functions. Transformation can be achieved using either chemical or physical methods, e.g., electroporation. Bulk electroporation offers several advantages over chemical methods, including high transformation efficiency, but its application is limited due to the high numbers of cells and plasmids needed as a result of the high death rate of cells during this process, and the difficulty in electroporating single cells. Synthetic inorganic gene nanocarriers have received limited attention in the transformation of bacterial cells. Here we present a plasmid delivery system based on water dispersible multi-walled carbon nanotubes (CNTs) that can simultaneously target the bacterial surface and deliver the plasmids into the cells via temporary nanochannels across the cell envelope. Transformation experiments performed on E. coli provide evidence for the high potential of CNTs for nanoscale cell electroporation.

In this study, we describe the spatial organization of CAL-72 osteoblast-like cells on arrays of vertically aligned multi-walled carbon nanotubes (VACNTs). It was observed that, unlike cell growth on non-patterned surfaces, the cell attachment and spreading process on VACNTs was significantly enhanced. Additionally, since carbon nanotubes are known to possess resilient mechanical properties and are chemically stable, the effect of periodic arrays of VACNTs on CAL-72 osteoblast-like cells was also studied. The periodicity and alignment of VACNTs considerably influenced growth, shape and orientation of the cells by steering toward the nanopattern. This situation is of great interest for the potential application of VACNTs in bone bioenginnering. This data provides evidence that CAL-72 osteoblast-like cells can sense physical features at the nanoscale. These results give a fascinating insight into the ways in which cell growth can be influenced by man-made nanostructures and could provide a framework for achieving controlled cell guidance with controlled organization and special physical properties.