Flore Keymeulen

Controlled membrane translocation provides a mechanism for signal transduction and amplification

Transmission and amplification of chemical signals across lipid bilayer membranes is of profound significance in many biological processes, from the development of multicellular organisms to information processing in the nervous system. In biology, membrane-spanning proteins are responsible for the transmission of chemical signals across membranes, and signal transduction is often associated with an amplified signalling cascade. The ability to reproduce such processes in artificial systems has potential applications in sensing, controlled drug delivery and communication between compartments in tissue-like constructs of synthetic vesicles. Here we describe a mechanism for transmitting a chemical signal across a membrane based on the controlled translocation of a synthetic molecular transducer from one side of a lipid bilayer membrane to the other. The controlled molecular motion has been coupled to the activation of a catalyst on the inside of a vesicle, which leads to a signal-amplification process analogous to the biological counterpart.

Paramagnetic Relaxation Enhancement Experiments: A Valuable Tool for the Characterization of Micellar Nanodevices

Micellar incorporation of hydrophobic molecular receptors is a promising strategy to obtain efficient nanodevices that work in water. In order to fully evaluate the potential of this approach, information on the localization and orientation of the receptor inside the micelle are necessary. Systematic studies undertaken on a uranyl-salophen receptor incorporated into CTABr and CTACl micelles show that nuclear magnetic resonance paramagnetic relaxation enhancement (NMR-PRE) experiments are particularly suitable to provide this type of information. The effect on the measurements of surfactant concentration, nature of the surfactant polar head, and ionic strength is also reported. Notably the normalization procedure applied to the obtained data can be considered of general application, thus enabling the comparison of information collected for different types of supramolecular micelle/receptor systems.