19F MRI detection of β-galactosidase activity for imaging of gene expression

Abstract

Imaging of gene expression by magnetic resonance imaging (MRI) yields direct information regarding living systems that cannot be obtained via other methods. In this study, we report the rational design and synthesis of a novel ¹⁹F MRI probe that detects β-galactosidase (β-gal) activity, enabling the imaging of gene expression in cells. The ¹⁹F MRI signal of the probe was quenched by the intramolecular paramagnetic resonance enhancement from a Gd³⁺ ion. A contrivance was made in the probe structure to recover the ¹⁹F MRI signal after hydrolysis by β-gal with a following self-immolative reaction. This ¹⁹F MRI signal change was observed in the physiological aqueous condition. The probe could also detect β-gal activity in fixed HEK293T cells. In conclusion, this new probe enables the ¹⁹F MRI detection of cellular gene expression. The probe design strategy is also expected to lead to the development of MRI probes for a wide variety of hydrolase activities.