Rosette nanotubes show low acute pulmonary toxicity in vivo.

Nanotubes are being developed for a large variety of applications ranging from electronics to drug delivery. Common carbon nanotubes such as single-walled and multi-walled carbon nanotubes have been studied in the greatest detail but require solubilization and removal of catalytic contaminants such as metals prior to being introduced to biological systems for medical application. The present in vivo study characterizes the degree and nature of inflammation caused by a novel class of self-assembling rosette nanotubes, which are biologically inspired, naturally water-soluble and free of metal content upon synthesis. Upon pulmonary administration of this material we examined responses at 24 h and 7d post-exposure. An acute inflammatory response is triggered at 50 and 25 microg doses by 24 h post-exposure but an inflammatory response is not triggered by a 5 microg dose. Lung inflammation observed at a 50 microg dose at 24 h was resolving by 7d. This work suggests that novel nanostructures with biological design may negate toxicity concerns for biomedical applications of nanotubes. This study also demonstrates that water-soluble rosette nanotube structures represent low pulmonary toxicity, likely due to their biologically inspired design, and their self-assembled architecture.