Sensitive CEST agents based on nucleic acid imino proton exchange: detection of poly(rU) and of a dendrimer-poly(rU) model for nucleic acid delivery and pharmacology.

TitleSensitive CEST agents based on nucleic acid imino proton exchange: detection of poly(rU) and of a dendrimer-poly(rU) model for nucleic acid delivery and pharmacology.
Publication TypeJournal Article
Year of Publication2003
AuthorsSnoussi K, Bulte JWM, Guéron M, van Zijl PCM
JournalMagnetic resonance in medicine : official journal of the Society of Magnetic Resonance in Medicine / Society of Magnetic Resonance in Medicine
Volume49
Issue6
Pagination998-1005
Date Published2003 Jun
Abstract

It is shown that the exchange properties of the imino and hydroxyl protons of polyuridilic acid (poly(rU)) allow use of this compound as a chemical-exchange saturation transfer (CEST) contrast agent. A proton/proton sensitivity enhancement factor of over 5000 per imino proton allowed the detection of a few micromolar of polymer (2000 uridine units; 644 kD) with a 50% change in the water signal. The enhancement factor would increase further at even lower concentrations, opening up the submicromolar range. When poly(rU) was complexed to a dendrimer carrying 250 positive charges, the stoichiometry was approximately one RNA for 10 dendrimers. The sensitivity enhancement was reduced but remained large (2300/imino proton), bringing enhanced CEST visibility to the dendrimers. The net charge of the complex was positive, suggesting that the complexed dendrimers would still interact with cell membranes, and that the RNA-dendrimer complex could provide a model for a gene delivery system with good CEST visibility.

Alternate JournalMagn Reson Med