Anisotropic gold nanorods (GNRs) provide many promising applications in optics, electronics, catalysis, biological detection, cellular imaging, and cancer photo-thermal therapy. A challenge is to stabilize and functionalize GNRs and disperse them well in aqueous solution to expand their functionality and potential use in biologically related applications.

Quan Li, Kent State University, Ohio, USA, and colleagues report the preparation and characterization of gold nanorods (GNRs) protected by a hydrophilic cucurbit[7]uril-based-pseudorotaxane anchored monolayer. The resulting GNRs covered with both cucurbit[7]uril-based pseudo[2]rotaxane disulfide and sodium thioctate on their entire surface through strong covalent S–Au linkages were found to be water-soluble as well as very stable in both solution and the solid state.

The shorter sodium thioctate, which fills up the potential space on the GNR surface between the pseudorotaxane molecules, not only acts as a stabilizer but also provides better water solubility.

• Hydrophilic Cucurbit[7]uril-Pseudorotaxane-Anchored-Monolayer-Protected Gold Nanorods,
  Xiang Ma, Yuhua Xue, Liming Dai, Augustine Urbas, Quan Li,
  Eur. J. Inorg. Chem. 2013.
  DOI:10.1002/ejic.201300010