title: Development and characterization of new nanoscaled ultrasound active lipid dispersions as contrast agents.
abstract: Ultrasound contrast agents are widely used in clinical diagnosis. In recent years, the use of ultrasound contrast agents as therapeutic agents has gained a lot of attention. Of special interest are ultrasound-enhanced gene delivery in various tissues (e.g. cardiac, vascular, skeletal muscle and tumor tissue), ultrasound-enhanced protein delivery (e.g. insulin delivery) and ultrasound-enhanced delivery of small chemicals (e.g. doxorubicin, vancomycin). Commercially available ultrasound contrast agents such as SonoVue® or Optison® are ranged in a size of 2-8 μm. These micronscaled agents show a good ultrasound contrast enhancement and thus they are used for diagnostic imaging. But they are not suitable for targeted drug delivery to tumor tissues or blood clots because for these applications particles smaller than 700 nm are needed. In the present study, we developed new nanoscaled ultrasound contrast agents with a size between 70 and 300 nm. The lipid formulations show excellent contrast intensities using diagnostic ultrasound of about 1.4 MHz. The negatively charged colloidal dispersions are long-time stable under physiological conditions without loss of ultrasound reflectivity. The adjustable supramolecular organization of the carriers depends on the composition and varies from micellar to liposomal structures. The small size and the circulation stability of these systems make them promising for novel diagnostics and controlled drug release applications.
authors.affiliation: Department of Pharmaceutical Technology and Biopharmaceutics, University of Marburg, Marburg, Germany.
authors.forename: Elena Eva Julianne
authors.initials: EE
authors.lastname: Marxer
authors.forename: Jana
authors.initials: J
authors.lastname: Brüssler
authors.forename: Andreas
authors.initials: A
authors.lastname: Becker
authors.forename: Joachim
authors.initials: J
authors.lastname: Schümmelfeder
authors.forename: Rolf
authors.initials: R
authors.lastname: Schubert
authors.forename: Christopher
authors.initials: C
authors.lastname: Nimsky
authors.forename: Udo
authors.initials: U
authors.lastname: Bakowsky
mesh_terms: D003287:Contrast Media / Q000737:chemistry*; D020285:Cryoelectron Microscopy; D016503:Drug Delivery Systems; D004355:Drug Stability; D017078:Laser-Doppler Flowmetry; D009682:Magnetic Resonance Spectroscopy; D018625:Microscopy, Atomic Force; D046529:Microscopy, Electron, Transmission; D008956:Models, Chemical; D049329:Nanostructures / Q000737:chemistry*; D010316:Particle Size; D010743:Phospholipids / Q000737:chemistry*; D013459:Sulfur Hexafluoride / Q000737:chemistry; D013499:Surface Properties; D014465:Ultrasonics
chemical_list: D003287:Contrast Media; D010743:Phospholipids; C420843:contrast agent BR1; D013459:Sulfur Hexafluoride