title: Harmonic responses and cavitation activity of encapsulated microbubbles coupled with magnetic nanoparticles.
abstract: Encapsulated microbubbles coupled with magnetic nanoparticles, one kind of hybrid agents that can integrate both ultrasound and magnetic resonance imaging/therapy functions, have attracted increasing interests in both research and clinic communities. However, there is a lack of comprehensive understanding of their dynamic behaviors generated in diagnostic and therapeutic applications. In the present work, a hybrid agent was synthesized by integrating superparamagnetic iron oxide nanoparticles (SPIOs) into albumin-shelled microbubbles (named as SPIO-albumin microbubbles). Then, both the stable and inertial cavitation thresholds of this hybrid agent were measured at varied SPIO concentrations and ultrasound parameters (e.g., frequency, pressure amplitude, and pulse length). The results show that, at a fixed acoustic driving frequency, both the stable and inertial cavitation thresholds of SPIO-albumin microbubble should decrease with the increasing SPIO concentration and acoustic driving pulse length. The inertial cavitation threshold of SPIO-albumin microbubbles also decreases with the raised driving frequency, while the minimum sub- and ultra-harmonic thresholds appear at twice and two thirds resonance frequency, respectively. It is also noticed that both the stable and inertial cavitation thresholds of SonoVue microbubbles are similar to those measured for hybrid microbubbles with a SPIO concentration of 114.7 μg/ml. The current work could provide better understanding on the impact of the integrated SPIOs on the dynamic responses (especially the cavitation activities) of hybrid microbubbles, and suggest the shell composition of hybrid agents should be appropriately designed to improve their clinical diagnostic and therapeutic performances of hybrid microbubble agents.
authors.affiliation: Key Laboratory of Modern Acoustics (MOE), Department of Physics, Collaborative Innovation Center of Advanced Microstructure, Nanjing University, Nanjing 210093, China.
authors.forename: Yuyang
authors.initials: Y
authors.lastname: Gu
authors.affiliation: Key Laboratory of Modern Acoustics (MOE), Department of Physics, Collaborative Innovation Center of Advanced Microstructure, Nanjing University, Nanjing 210093, China.
authors.forename: Chuyi
authors.initials: C
authors.lastname: Chen
authors.affiliation: Key Laboratory of Modern Acoustics (MOE), Department of Physics, Collaborative Innovation Center of Advanced Microstructure, Nanjing University, Nanjing 210093, China. Electronic address: juantu@nju.edu.cn.
authors.forename: Juan
authors.initials: J
authors.lastname: Tu
authors.affiliation: Key Laboratory of Modern Acoustics (MOE), Department of Physics, Collaborative Innovation Center of Advanced Microstructure, Nanjing University, Nanjing 210093, China.
authors.forename: Xiasheng
authors.initials: X
authors.lastname: Guo
authors.affiliation: Key Laboratory of Modern Acoustics (MOE), Department of Physics, Collaborative Innovation Center of Advanced Microstructure, Nanjing University, Nanjing 210093, China.
authors.forename: Hongyi
authors.initials: H
authors.lastname: Wu
authors.affiliation: Key Laboratory of Modern Acoustics (MOE), Department of Physics, Collaborative Innovation Center of Advanced Microstructure, Nanjing University, Nanjing 210093, China; The State Key Laboratory of Acoustics, Chinese Academy of Science, Beijing 10080, China. Electronic address: dzhang@nju.edu.cn.
authors.forename: Dong
authors.initials: D
authors.lastname: Zhang
mesh_terms: D000418:Albumins / Q000737:chemistry; D002214:Capsules; D003287:Contrast Media / Q000737:chemistry* / Q000627:therapeutic use; D005290:Ferric Compounds / Q000737:chemistry*; D008279:Magnetic Resonance Imaging; D059346:Magnets / Q000737:chemistry*; D045423:Microbubbles / Q000627:therapeutic use; D053758:Nanoparticles / Q000737:chemistry*; D000069453:Ultrasonic Waves; D014463:Ultrasonography
chemical_list: D000418:Albumins; D002214:Capsules; D003287:Contrast Media; D005290:Ferric Compounds; C000499:ferric oxide
keywords: Hybrid contrast agents; Inertial cavitation; Pressure threshold; Stable cavitation; Superparamagnetic iron oxide nanoparticles