What led you to specialise in supramolecular chemistry?rnThe philosophical breadth of supramolecular chemistry, especially in the hands of Jean-Marie Lehn and Seiji Shinkai, was clear to see during the early 1980s. Around this time, I had just completed my PhD research in organic photochemistry at Queen's University Belfast under Jim Grimshaw. Combining photochemistry with supramolecular chemistry permitted the fluorescence signalling of alkali metal ions-a virgin field at the time.rnYour research helped develop blood diagnostic cassettes. How does this chemistry work?rnFluorescent molecular sensors can gather information about atomic or molecular behaviour from environments of nanometre dimensions. We developed sensors which contain a fluorescent unit and a receptor unit joined through a spacer module. This supermolecule loses its fluorescence capability owing to an inter-module photoinduced electron transfer (PET) quite similar to that seen in green plant photosynthesis. This PET process is stopped the moment the receptor module captures its target, for example a sodium ion, thereby switching the suppressed fluorescence back on. Thus the fluorescence signal measures the concentration level of the target species.rnIn collaboration with Roche Diagnostics (now Optimedical), we produced fluorescent PET sensors held inside small plastic cassettes. These sensors respond to various blood gases and electrolytes and are used in hospital critical care units, ambulances, general practice surgeries and even veterinary environments. The cassettes have had sales of over 55 million US dollars so far.
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