In situ modification of the surface of gold colloidal particles. Preparation of cyclodextrin-based rotaxanes supported on gold nanospheres

A new method for the surface derivatization of gold colloidal particles is reported. The method is based on the aqueous solubilization of aliphatic th iols by alpha-cyclodextrin, which effectively binds to the aliphatic chains and carries the hydrophobic thiol molecules to the surface of the gold par ticles, where they undergo chemisorption. This method can be used to prepar e gold colloidal particles (diameter > 10 nm) modified with long chain alka nethiolates. if the alkanethiol contains a bulky terminal group, such as fe rrocene, the alpha-cyclodextrin host is trapped after surface attachment, y ielding cyclodextrin-based rotaxanes supported on the gold nanospheres.