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包膜黏弹特性显著影响微气泡超声造影剂的诊断及治疗应用效果.本文结合原子力显微镜技术及声衰减特性测量提出了一种对微气泡造影剂包膜黏弹特性定量表征的新方法.首先采用原子力显微镜技术进行机械特性分析得到包膜微气泡的有效硬度及体弹性模量;然后测量声衰减特性,基于微气泡动力学理论,计算包膜微气泡的体黏度系数.为验证方法的有效性,实验制备了直径为1—5μm的白蛋白包膜微气泡造影剂,原子力显微镜测量的有效硬度和体弹性模量分别为0.149±0.012 N/m和8.31±0.667 MPa,并与粒径无关.声衰减特性测量和动力学理论拟合的包膜微气泡的体黏度系数为0.374±0.003 Pa·s.该方法可推广至其他种类包膜微气泡的黏弹特性表征,对超声造影剂的制备及其诊断和治疗应用有积极意义.
The capsule viscoelasticity significantly affects the diagnosis and therapeutic effect of microbubble ultrasound contrast agent.This paper presents a new method for quantitative characterization of the capsule viscoelastic properties of microbubble contrast agent with atomic force microscopy and acoustic attenuation characteristics.Firstly, The mechanical properties of AFM were used to obtain the effective microhardness and bulk modulus of the coated microbubbles. Then, the sound attenuation characteristics were measured and the bulk viscosity coefficients of the coated microbubbles were calculated based on the dynamics of microbubbles. To validate the method, The albumin-coated microbubbles with diameter of 1-5μm were prepared experimentally. The effective hardness and bulk modulus measured by AFM were 0.149 ± 0.012 N / m and 8.31 ± 0.667 MPa, respectively, which were independent of particle size .The bulk viscosity coefficient of the coated microbubbles fitted by sound attenuation characteristic measurement and kinetic theory is 0.374 ± 0.003 Pa · s.This method can be extended to other types of envelope microbubbles viscoelastic characterization, Preparation and diagnosis and treatment of positive applications.