Selective complexation and sensitive analysis of charge diffuse cationic species using lipophilic cyclodextrins

Lipophilic peralkylated cyclodextrins are useful ionophores for the selective binding of a variety of size-matched charge-diffuse cationic species. Chiral potentiometric sensors may be devised using plasticised membrane electrodes, while voltammetric sensors may be fabricated that allow subnanomolar levels of detection of electron-rich aromatic cations. The observation of the binding of size-matched tetraalkylammonium ions has led to the development of sensitive methods of detection for species such as acetylcholine. When lipophilic cyclodextrins are coupled to enzymes in a disposable biosensor, a highly specific method of analysis is achieved giving sub-picomolar levels of detection.