MR contrast agent composed of cholesterol and peptide nucleic acids: design, synthesis and cellular uptake

A new mRNA targeting contrast agent consisting of three main functional domains, (i) gadolinium based magnetic resonance reporter part, (ii) antisense peptide nucleic acids targeted to mRNA, and (iii) cholesterol as the delivery vector, was developed and synthesized. The new contrast agent showed efficient cellular uptake and significant contrast enhancement at very low labeling concentrations (0.5 microM). However, after uptake into cells the agent was located predominantly in endosomes like a similar cell penetrating peptide conjugated probe. Our results indicate that this newly developed contrast agent could be used for the labeling of cells for optical as well as magnetic resonance imaging.