Nitric Oxide Gas in Carbon Nanohorn/Fluorinated Dendrimer/Fluorinated Poly(ethylene glycol)-Based Hierarchical Nanocomposites as Therapeutic Nanocarriers.

Nitric oxide (NO) gas nanocarrier materials were prepared via a hierarchical assembly of poly(amido amine) dendrimers with fluorocarbon binding sites (DEN- F ) and fluorinated poly(ethylene glycol) ( F -PEG) on nitrogen-doped carbon nanohorns (NCNHs). The loading abilities of NO gas in these nanocarrier materials increased with the nitrogen doping of CNH and hierarchies formed by DEN- F and F -PEG. Especially, the ability of CNH-based nanocomposite materials was better than that of graphene-based materials. The loading of NO gas arose an infrared absorption band at 1387 cm -1 and increased the intensity ratio of D and G bands in Raman spectra, although these phenomena diminished after the degas treatment. The antimicrobial effects on bacteria ( Escherichia coli and Staphylococcus aureus ) increased depending on the loading amount of NO gas. It was confirmed from these results that NO gas weakly interacts with nitrogen-doped CNH and is trapped in the void volumes of DEN- F and F -PEG hierarchies. Thus, the concentric hierarchy is preferable for slow release of NO gas due to the void volumes in DEN- F , F -PEG, and CNH hierarchical organization. This sustained release of NO gas is advantageous with regards to the potential biomedical gas therapy against bacteria and other parasites.