title: Ultrasound triggered drug delivery with liposomal nested microbubbles.
abstract: When ultrasound contrast agent microbubbles are nested within a liposome, damage to the liposome membrane caused by both stable and inertial cavitation of the microbubble allows for release of the aqueous core of the liposome. Triggered release was not accomplished unless microbubbles were present within the liposome. Leakage was tested using fluorescence assays developed specifically for this drug delivery vehicle and qualitative measurements using an optical microscope. These studies were done using a 1 MHz focused ultrasound transducer while varying parameters including peak negative ultrasound pressure, average liposome diameter, and microbubble concentration. Two regimes exist for membrane disruption caused by cavitating microbubbles. A faster release rate, as well as permanent membrane damage are seen for samples exposed to high pressure (2.1-3.7 MPa). A slower release rate and dilation/temporary poration are characteristic of stable cavitation for low pressure studies (0.54-1.7 MPa).
authors.affiliation: Department of Chemical Engineering, Drexel University, 3141 Chestnut St, Philadelphia, PA 19104, United States. Electronic address: nrw25@drexel.edu.
authors.forename: N
authors.initials: N
authors.lastname: Wallace
authors.affiliation: Department of Chemical Engineering, Drexel University, 3141 Chestnut St, Philadelphia, PA 19104, United States. Electronic address: spw22@drexel.edu.
authors.forename: S P
authors.initials: SP
authors.lastname: Wrenn
mesh_terms: D016503:Drug Delivery Systems / Q000379:methods*; D005452:Fluoresceins / Q000494:pharmacology; D005456:Fluorescent Dyes / Q000494:pharmacology; D008081:Liposomes / Q000737:chemistry*; D045423:Microbubbles; D013053:Spectrophotometry; D014465:Ultrasonics
chemical_list: D005452:Fluoresceins; D005456:Fluorescent Dyes; D008081:Liposomes; C007740:fluorexon
keywords: Cavitation; Drug delivery; Microbubble; Sonoporation; Ultrasound