CHEMICAL SENSING BASED ON MOLECULAR RECOG NITION AT MEMBRANE SURFACES

The signal transduction/amplification based on the change of membrane potential or permeability can be modulated by molecular recognition of analytes with artificial receptors at the membrane surfaces, making i t a very interesting approach to chemical sensing. Membrane potential was changed with the following modes of molecular recognition at the l iquid membrane surfaces. (i) Multitopic hydrogen bonding of nucleobase s or inorganic anions by receptors with cytosine residue or with two u rea (thiourea) groups, respectively. (ii) Inclusion of nonpolar moieti es of amine analytes by a calix [6]arene hexaester or a beta-cyclodext rin derivative. The principles of ion-channel sensors based on chemica lly switchable membrane permeability changes are demonstrated by inter molecular as well as intramolecular channels using monolayers formed w ith hydrogen bonding receptors and the beta-cyclodextrin derivative. F inally, examples of fluorescence mediated sensing of guanosine derivat ives based on multitopic hydrogen bonding and orthophosphate ion senso rs based on a quartz crystal microbalance are also presented.