title: Nanoemulsion contrast agents with sub-picomolar sensitivity for xenon NMR.
abstract: A new type of contrast agent for Xe NMR based on surfactant-stabilized perfluorocarbon-in-water nanoemulsions has been produced. The contrast agent uses dissolved hyperpolarized xenon gas as a nonperturbing reporting medium, as xenon freely exchanges between aqueous solution and the perfluorocarbon interior of the droplets, which are spectroscopically distinguishable and allow for chemical exchange saturation transfer (CEST) detection of the agent. Nanoemulsions with droplet diameters between 160 and 310 nm were produced and characterized using hyperpolarized (129)Xe combined with CEST detection. Saturation parameters were varied and data were modeled numerically to determine the xenon exchange dynamics of the system. Nanoemulsion droplets were detected at concentrations as low as 100 fM, corresponding to <1 μL of perfluorocarbon per liter of solution. The straightforward, inexpensive production of these agents will facilitate future development toward molecular imaging and chemical sensing applications.
authors.affiliation: Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Todd K
authors.initials: TK
authors.lastname: Stevens
authors.forename: R Matthew
authors.initials: RM
authors.lastname: Ramirez
authors.forename: Alexander
authors.initials: A
authors.lastname: Pines
mesh_terms: D003287:Contrast Media / Q000138:chemical synthesis* / Q000737:chemistry; D004655:Emulsions / Q000138:chemical synthesis / Q000737:chemistry; D005466:Fluorocarbons / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry; D014867:Water / Q000737:chemistry; D014978:Xenon / Q000737:chemistry*
chemical_list: D003287:Contrast Media; D004655:Emulsions; D005466:Fluorocarbons; D013501:Surface-Active Agents; D014867:Water; D014978:Xenon