A pilot toxicology study of single-walled carbon nanotubes in a small sample of mice.

Single-walled carbon nanotubes are currently under evaluation in biomedical applications, including in vivo delivery of drugs, proteins, peptides and nucleic acids (for gene transfer or gene silencing), in vivo tumour imaging and tumour targeting of single-walled carbon nanotubes as an anti-neoplastic treatment. However, concerns about the potential toxicity of single-walled carbon nanotubes have been raised. Here we examine the acute and chronic toxicity of functionalized single-walled carbon nanotubes when injected into the bloodstream of mice.

Supramolecular chemistry on water-soluble carbon nanotubes for drug loading and delivery.

We show that large surface areas exist for supramolecular chemistry on single-walled carbon nanotubes (SWNTs) prefunctionalized noncovalently or covalently by common surfactant or acid-oxidation routes. Water-soluble SWNTs with poly(ethylene glycol) (PEG) functionalization via these routes allow for surprisingly high degrees of pi-stacking of aromatic molecules, including a cancer drug (doxorubicin) with ultrahigh loading capacity, a widely used fluorescence molecule (fluorescein), and combinations of molecules. Binding of molecules to nanotubes and their release can be controlled by varying the pH.

Soluble single-walled carbon nanotubes as longboat delivery systems for platinum(IV) anticancer drug design.

Amine functionalized soluble single walled carbon nanotubes (SWNTs) were derivatized with cisplatin prodrug conjugates as a delivery system by which to internalize multiple prodrug centers. The platinum(IV) complex, ,,-[Pt(NH)Cl(OEt)(OCCHCHCOH)], was tethered to the surface of the carbon nanotubes through peptide linkages formed by the reaction of the SWNT-tethered amines with the carboxylate moiety. The SWNTs are taken into testicular cancer cells by endocytosis where the drop in pH facilitates reductive release of the platinum(II) core complex, which then readily diffuses throughout the cell, as determined by platinum atomic absorption spectroscopy.

Noncovalent functionalization of carbon nanotubes by fluorescein-polyethylene glycol: supramolecular conjugates with pH-dependent absorbance and fluorescence.

We report the use of fluorescein-polyethylene glycol (Fluor-PEG) to non-covalently functionalize single-walled carbon nanotubes (SWNTs) for obtaining aqueous-soluble nanotube conjugates (Fluor-PEG/SWNT) and simultaneously affording fluorescence labels to nanotubes. We find serendipitously that fluorescein, a widely used fluorophore, can strongly adsorb onto the sidewall of the SWNTs likely via π-stacking, and the hydrophilic PEG chain imparts high aqueous solubility. Interaction between fluorescein and SWNT is pH dependent; it weakens as the pH is increased, causing the Fluor-PEG/SWNT conjugate to be less stable at high pHs.