title: Supramolecular chemistry on water-soluble carbon nanotubes for drug loading and delivery.
abstract: 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. The strength of pi-stacking of aromatic molecules is dependent on nanotube diameter, leading to a method for controlling the release rate of molecules from SWNTs by using nanotube materials with suitable diameter. This work introduces the concept of "functionalization partitioning" of SWNTs, i.e., imparting multiple chemical species, such as PEG, drugs, and fluorescent tags, with different functionalities onto the surface of the same nanotube. Such chemical partitioning should open up new opportunities in chemical, biological, and medical applications of novel nanomaterials.
authors.affiliation: Department of Chemistry, Stanford University, Stanford, California 94305, USA.
authors.forename: Zhuang
authors.initials: Z
authors.lastname: Liu
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Sun
authors.forename: Nozomi
authors.initials: N
authors.lastname: Nakayama-Ratchford
authors.forename: Hongjie
authors.initials: H
authors.lastname: Dai
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D015374:Biosensing Techniques; D045744:Cell Line, Tumor; D004317:Doxorubicin / Q000737:chemistry / Q000494:pharmacology; D004337:Drug Carriers / Q000737:chemistry*; D019793:Fluorescein / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010084:Oxidation-Reduction; D010316:Particle Size; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry; D012995:Solubility; D013501:Surface-Active Agents / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D000970:Antineoplastic Agents; D004337:Drug Carriers; D037742:Nanotubes, Carbon; D004364:Pharmaceutical Preparations; D013501:Surface-Active Agents; D014867:Water; D011092:Polyethylene Glycols; D004317:Doxorubicin; D019793:Fluorescein