Copper(ii) complexes for cysteine detection using 19F magnetic resonance

Abstract

Cysteine plays an essential role in maintaining cellular redox homeostasis and perturbations in cysteine concentration are associated with cardiovascular disease, liver disease, and cancer. ¹⁹F MRI is a promising modality for detecting cysteine in biology due to its high tissue penetration and negligible biological background signal. Herein we report fluorinated macrocyclic copper complexes that display a ¹⁹F NMR/MRI turn-on response following reduction of the Cu(II) complexes by cysteine. The reactivity with cysteine was studied by monitoring the appearance of a robust diamagnetic ¹⁹F signal following addition of cysteine in conjunction with UV-vis and EPR spectroscopies. Importantly, complexes with –CH₂CF₃ tags display good water solubility. Studies with this complex in HeLa cells demonstrate the applicability of these probes to detect cysteine in complex biological environments.