SYNTHESIS OF CRYPTOPHANE-1.1.1 AND ITS APPLICATIONS TO MAGNETIC RESONANCE IMAGING John Rhoat, Department of Chemistry, Community College of Rhode Island, Warwick, RI; Joe Brown, Brenton DeBoef, Department of Chemistry, University of Rhode Island, Kingston, RI RI-INBRE Summer Undergraduate Research Fellowship Program Cryptophanes are hollow, cage-shaped molecules of interest with unique molecular encapsulation properties. These properties enable them to trap molecules or atoms, such as xenon, within their structure. Xenon-129 Magnetic Resonance Imaging (Xe-MRI) is a powerful tool capable of non-invasive scanning of biological tissue. Xenon is an inert, non-toxic, noble gas that displays no MRI background signal in biological tissue. When inhaled, xenon rapidly enters the bloodstream, distributing the gas to all the body’s organs, including the brain. A new technique using hyperpolarized xenon-129 with MRI (HP-Xe MRI) provides an increase in magnetic resonance, allowing for imaging with 100,000 times higher resolution than traditional MRI. Further signal amplification required to image at picomolar concentrations can be achieved through hyperpolarized chemical saturation transfer (HyperCEST), which capitalizes on the diffusion of xenon in and out of t he cryptophane cages. Cryptophane-1.1.1 displays the highest xenon binding constant in organic solution known to date. Originally, it was believed that xenon’s high affinity for cryptophane-1.1.1 made it optimal for sensing applications such as HP-Xe MRI. However, we hypothesize that xenon’s high affinity for cryptophane-1.1.1 may no longer be optimal for HyperCEST Hp Xe-MRI. We predict that cryptophane-2.2.2, a slightly larger cage molecule, would be better suited for HyperCEST enhancement because this cage allows for more rapid xenon diffusion. Optimal cage structure still remains undetermined until a systematic study of novel cryptophane cages is completed. The goal of this work is synthesis of functionalized cryptophane-1.1.1 molecules, which could target biological areas of interest such as tumors and areas of inflammation. Water-soluble functionalized cryptophanes could provide the capability of non-invasive imaging of biological processes at the molecular and cellular level. Such technology could be applied Hp-Xe MRI both in-vivo and in-vitro, providing opportunity for major biological and medical advancements.
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