Smith Moira J, Ho Vincent H B, Darton Nicholas J, Slater Nigel K H
Department of Chemical Engineering and Biotechnology, University of Cambridge, New Museums Site, Cambridge, United Kingdom.
Ultrasound Med Biol. 2009 Jun;35(6):1010-4. doi: 10.1016/j.ultrasmedbio.2008.12.010. Epub 2009 Feb 28.
High intensity focused ultrasound (HIFU) induced inertial cavitation has been shown to improve release and cellular uptake of drugs. The effects of magnetite nanoparticle agglomerates (290+/-10nm diameter), silica coated magnetite nanoparticle agglomerates (320+/-10nm diameter) and silica particles (320+/-10nm diameter) suspended in MilliQ water on the degree of inertial cavitation due to HIFU were investigated. The HIFU transducer was operated at a frequency of 1.1 MHz, 1.67 kHz pulse repetition frequency, with applied duty cycles (DC) between 0% and 5% and different peak negative focal pressures (PNFPs) applied up to 7.2 MPa. The inertial cavitation dose (ICD: time averaged root-mean-squared broadband noise amplitude in the frequency domain) was measured in the presence and absence of nanoparticles when subjected to HIFU. Magnetite nanoparticle agglomerates caused a significant increase in the ICD above 2.7 MPa PNFP compared with MilliQ water, silica coated magnetite agglomerates and silica particles. With the dramatic increase in ICD on introduction of these magnetite agglomerates, this technique could provide a method of HIFU triggered drug delivery by enhancing inertial cavitation. The superparamagnetic properties of these particles offer the possibility of magnetic targeting to the site of disease.
高强度聚焦超声（HIFU）诱导的惯性空化已被证明可改善药物的释放和细胞摄取。研究了悬浮在超纯水（MilliQ水）中的磁铁矿纳米颗粒团聚体（直径290±10nm）、二氧化硅包覆的磁铁矿纳米颗粒团聚体（直径320±10nm）和二氧化硅颗粒（直径320±10nm）对HIFU引起的惯性空化程度的影响。HIFU换能器以1.1MHz的频率、1.67kHz的脉冲重复频率运行，施加的占空比（DC）在0%至5%之间，并施加高达7.2MPa的不同峰值负焦压（PNFP）。在施加HIFU时，在有和没有纳米颗粒的情况下测量惯性空化剂量（ICD：频域中的时间平均均方根宽带噪声幅度）。与超纯水、二氧化硅包覆的磁铁矿团聚体和二氧化硅颗粒相比，磁铁矿纳米颗粒团聚体在PNFP高于2.7MPa时导致ICD显著增加。随着这些磁铁矿团聚体引入后ICD的急剧增加，该技术可通过增强惯性空化提供一种HIFU触发的药物递送方法。这些颗粒的超顺磁性特性提供了磁靶向疾病部位的可能性。
