title: Encapsulated microbubbles and echogenic liposomes for contrast ultrasound imaging and targeted drug delivery.
abstract: Micron- to nanometer-sized ultrasound agents, like encapsulated microbubbles and echogenic liposomes, are being developed for diagnostic imaging and ultrasound mediated drug/gene delivery. This review provides an overview of the current state of the art of the mathematical models of the acoustic behavior of ultrasound contrast microbubbles. We also present a review of thein vitroexperimental characterization of the acoustic properties of microbubble based contrast agents undertaken in our laboratory. The hierarchical two-pronged approach of modeling contrast agents we developed is demonstrated for a lipid coated (Sonazoid™) and a polymer shelled (poly D-L-lactic acid) contrast microbubbles. The acoustic and drug release properties of the newly developed echogenic liposomes are discussed for their use as simultaneous imaging and drug/gene delivery agents. Although echogenicity is conclusively demonstrated in experiments, its physical mechanisms remain uncertain. Addressing questions raised here will accelerate further development and eventual clinical approval of these novel technologies.
authors.affiliation: Department of Mechanical Engineering, University of Delaware, Newark DE 19716, USA.
authors.forename: Shirshendu
authors.initials: S
authors.lastname: Paul
authors.affiliation: Department of Pharmaceutical Sciences, North Dakota State University, Fargo ND 58108, USA.
authors.forename: Rahul
authors.initials: R
authors.lastname: Nahire
authors.affiliation: Department of Pharmaceutical Sciences, North Dakota State University, Fargo ND 58108, USA.
authors.forename: Sanku
authors.initials: S
authors.lastname: Mallik
authors.affiliation: Department of Mechanical and Aerospace Engineering, The George Washington University, Washington, DC 20052, USA.
authors.forename: Kausik
authors.initials: K
authors.lastname: Sarkar
keywords: Ultrasound contrast agents; drug delivery; encapsulated microbubbles; liposomes