No abstract

A method to control the release of the anti-cancer drug doxorubicin (Dox) from cylindrical nanocapsules, known as organic nanotubes (ONTs), is reported. Co-assembly of a tube-forming glycolipid and its hydrophobized analogue yield novel ONTs with both -COOH and hydrophobic benzyloxycarbonyl groups localized on cylindrical nanochannels. The hydrophobicity of the ONTs nanochannels is easily tunable by adjusting the mixing ratio of the two glycolipids in the co-assembly process. The resultant biologically stable ONTs are able to capture Dox with high efficiency into the cylindrical nanochannels via ion complexation between cationic Dox and anionic -COO(-) , and the release of Dox from hybrid ONTs is effectively controlled by tuning the electrostatic interaction and the hydrophobicity. This controlled release by tuning the hydrophobicity of the ONTs' nanochannels greatly reduces the cytotoxicity of Dox@ONTs for HeLa cells.

We have synthesized bicyclic azobenzene dimers that possess enantiomers whose racemization rates could be controlled reversibly through E-Z photoisomerization of the azobenzene units. Upon alternating the exposure to r- and l-CPL, we were able to repeatedly perform partial enrichment of (S)- and (R)- enantiomers, respectively.

The redox chemistry of single-walled carbon nanotubes (SWCNTs) was examined by using optical absorption spectroscopy measurements in the presence of sodiumd odecyl sulfate (SDS) and its analog surfactants, that is, sodium 1-undecanesulfonate (SUS) and sodium dodecylbenzenesulfonate (SDBS). Redox reactions of the SWCNTsw ere observed in the SDS andS US solutions, whereas such reactions were suppressed in the SDBS solution. Molecular dynamics simulations were performed to investigate the assembly of the surfactants arounda nS WCNT.S DS and SUS were shown to primarily form single layers on the SWCNT and certain solvent-exposed areas, whereas SDBS predictably densely coated the SWCNTs. The resultss uggest that the SDBS layer on the SWCNT surfaces preventsc harge-transfer reactions;i n contrast,t he sparse layers of SDS and SUS allow the redox chemistry through the charge-transferr eactions. Interestingly,apositively charged SWCNT as am odel for the oxidized SWCNT showed an increase in the number of surfactant molecules around the SWCNT in the SDS and SUS solutions owing to electrostatic interaction, which is relatedt ot he chirality-dependenceoftheSWCNT colloidalstability.

A bipolar glycolipid self-assembles into organic nanotubes upon its chelation with an anticancer drug cis-dichlorodiamineplatinum(II) (CDDP). The facile synthesis of glycolipid, chelation-assisted formation of the nanotubes, and efficient loading and prolonged release of CDDP demonstrate a new approach to high-axial supramolecular drug nanocarriers.