Transition-metal-based Chemosensing Ensembles: ATP Sensing in Physiological Conditions

Abstract

Sensing of biologically relevant anionic substrates in physiological conditions, employing the strategy of the chemosensing ensembles, is reported. Coordination of a fluorescent indicator to a dicopper(II) polyazamacrocyclic receptor ([Cu²(L)]) results in the collapse of its fluorescence emission. Competitive binding of substrates for the receptor releases the indicator in solution, with full emission recovery. The spectral changes obtained for some indicators and substrates were analysed to determine their respective association constants for the receptor. Discrimination of micromolar ATP quantities from other interferents (small inorganic anions and well-known neurotransmitters) is improved by a judicious choice of the indicator, the resulting ATP sensor promising interesting biological applications.

Keywords:

• Fluorescent probes
• Molecular recognition
• ATP
• Neurotransmitters
• Macrocyclic complexes

Acknowledgements

This work was supported by CNR Progetto Finalizzato “Biotecnologie”. N.M. is grateful to the European Commission for a “Marie Curie” fellowship (HPMF-CT-2000-01030). We thank Professor Fabio Grohovaz and Dr Franca Codazzi from the Neuroscience Department of the Scientific Institute San Raffaele, Milan, for suggestions on biological applications, and Dr Donatella Sacchi for helpful discussions. Finally, our greatest thanks go to Professor Luigi Fabbrizzi for his continuous inspiration, help and support.

Notes

The Future of Supramolecular ChemistryI always liked Supramolecular Chemistry because of its borderline nature, and even if it is very difficult to predict where it can arrive, the road to take is quite clear. Supramolecular Chemistry should be the main route to connect chemistry to other disciplines like life sciences, materials engineering, logics and computing, in order to solve practical problems. Popular examples of close goals for scientists with a multidisciplinary knowledge are functionalisation of surfaces to obtain smart materials for data storage and nanosized electronic components and realization of light-powered molecular level machines. Another classical topic concerns real time monitoring of biologically relevant molecules during their activity in vitro or in vivo using synthetic sensors: the contribution here presented shows how we can try to answer to a classical biological sensing demand (i.e. revealing the presence of one single neurotransmitter in presence of many other) with a very simple and economic approach.Angelo Taglietti graduated in Chemistry from the University of Pavia, where he also obtained his PhD in 1996 with a thesis on Electron Transfer Processes in Supramolecular Chemistry, under the supervision of Professor Luigi Fabbrizzi. During postdoc research his main interests were focused on development of transition metal based receptors and sensors for anions. Since 1999 he has worked as a research associate in the University of Pavia, and his current research is centred on design of sensory systems for biologically relevant substrates, kinetic characterization of molecular translocations, design and synthesis of simple molecular level devices.