Under the covers

Why this research

"We are working on the development of novel MRI contrast agent for diagnostic imaging. These so-called xenon biosensors provide very high specificity and sensitivity. An integral part is a molecular host that traps the xenon as it is an inert gas and cannot be tethered to biomolecules through chemical bond formation. The detection relies on the principle that Xe is only bound temporarily to these hosts and we are searching for hosts with faster exchange rates compared to what people used so far.

"MRI has a large unused potential. Though the sensitivity is a serious limitation, there are ways to circumvent it under certain conditions. The potential applications would be extremely valuable in modern medical diagnostics."

Future developments

"We hope that this triggers more work by synthetic chemists to realise how much room for improvement we still have to make really smart contrast agents. People have optimised Gadolinium chelates for clinical MRI applications for over 20 years now, and others have developed genetically expressible fluorescent reporters for biomedical research. All these imaging techniques rely on optimised contrast agents and for Xe MRI, we are just at the beginning of an exciting development."

From the art desk

Fellow institute scientist, Dr Barth van Rossum worked on the creative artwork for the cover and here explains how the idea originated.

"An effective illustration should be both aesthetically pleasing and convey a clear narrative element, and we believe we managed to capture both aspects well.

"The host that traps the xenon is a cucurbituril - a molecule named after it’s pumpkin-like shape (pumpkins belong to the botanical family of ‘curcubita’). Hence, the idea to make a connection between the scientific work and Halloween almost naturally arose."

"The figure breaks down the scientific message of the paper into several easy-to-grasp elements. The fast xenon exchange is represented by the bats frantically flying in-and-out the pumpkin, which is contrasted to the slow exchange in the form of a lonely bat in a cage covered by spider webs.

"To guide the viewer in making the transition from the two molecules to their macroscopic counterparts, we added a second, less-conventional chemical representation – a pumpkin-coloured surface model and a metallic wireframe model. In addition, the sheets with hand-written notes in front of the two systems should help the viewer further to make the connection."

Read the paper: Identification, classification, and signal amplification of high-turnover gas binding hosts in ultra-sensitive NMR