title: High-frequency (20 to 40 MHz) acoustic response of liquid-filled nanocapsules.
abstract: Liquid-core nanoparticles are promising candidates for targeted ultrasound-controlled therapy, but their acoustic detection remains challenging. High-frequency (20 to 40 MHz) tone burst sequences were implemented with a programmable ultrasound biomicroscope to characterize acoustic response from perfluorooctyl bromide-core nanoparticles with thick poly(lactide-coglycolide) (PLGA) shells. Radio-frequency signals were acquired from flowing solutions of nanoparticles with two different shell-thickness-to-particle-radius ratios, solid PLGA nanoparticles, and latex nanobeads (linear controls). Normalized fundamental (20 MHz) and second-harmonic power spectral density (PSD) increased with particle concentration and was highest for the thinnest shelled particles. The second- harmonic PSD was detectable from the nanoparticles for peak rarefactional pressures (PRP) from 0.97 to 2.01 MPa at 23 cycles and for tone bursts from 11 to 23 cycles at 2.01 MPa. Their second-harmonic¿to¿fundamental ratio increased as a function of PRP and number of cycles. Within the same PRP and cycle ranges, the second-harmonic¿to¿fundamental ratios from matched concentration solutions of latex nanobeads and solid PLGA nanoparticles was more weakly detectable but also increased with PRP and number of cycles. Nanoparticles were detectable under flow conditions in vitro using the contrast agent mode of a high-frequency commercial scanner. These results characterize linear acoustic response from the nanoparticles (20 to 40 MHz) and demonstrate potential for their highfrequency detection.
authors.forename: Sara
authors.initials: S
authors.lastname: Jafari
authors.forename: Odile
authors.initials: O
authors.lastname: Diou
authors.forename: Jonathan
authors.initials: J
authors.lastname: Mamou
authors.forename: Gilles
authors.initials: G
authors.lastname: Renault
authors.forename: Elias
authors.initials: E
authors.lastname: Fattal
authors.forename: Nicolas
authors.initials: N
authors.lastname: Tsapis
authors.forename: S Lori
authors.initials: SL
authors.lastname: Bridal
mesh_terms: D003287:Contrast Media / Q000032:analysis / Q000737:chemistry / Q000528:radiation effects; D004058:Diffusion / Q000528:radiation effects; D004339:Drug Compounding / Q000379:methods; D005466:Fluorocarbons / Q000032:analysis / Q000737:chemistry* / Q000528:radiation effects*; D019220:High-Energy Shock Waves; D019344:Lactic Acid / Q000737:chemistry / Q000528:radiation effects; D053769:Nanocapsules / Q000737:chemistry* / Q000528:radiation effects*; D010316:Particle Size; D011100:Polyglycolic Acid / Q000737:chemistry / Q000528:radiation effects; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011829:Radiation Dosage; D012996:Solutions; D013010:Sonication / Q000379:methods*; D014463:Ultrasonography / Q000379:methods*
chemical_list: D003287:Contrast Media; D005466:Fluorocarbons; D053769:Nanocapsules; D012996:Solutions; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; C078626:perflexane