超声微泡低频动力学特性及其生物效应

理论上利用有耗散函数的Lagrange方程,建立了有壳微泡的R(t)运动方程,开展了自由空间中有壳微泡动力学特性的研究,表明微泡内外半径增量随声压的增大、超声频率的降低、初始内径的增大及壳厚的减薄而迅速增大。实验上,利用Mie散射技术在80°散射角和前向Mie散射检测新技术实验测量了微泡R(t)曲线;利用体视显微镜,实时观察了超声微泡对动物活体微血管损伤,开展了超声微泡生物效应的动物和细胞试验研究。结果表明:(1)超声作用下,微泡引起肿瘤中微血管壁周期性膨胀收缩而发生管壁破裂,形成血栓和微血管栓塞,抑制了肿瘤生长;(2)超声联合微泡可以破坏微血管内皮生长因子(VEGF)和肝癌细胞,可以减少肿瘤血管和癌细胞再生,因此,低频超声联合微泡技术是一种值得探索抑制肿瘤生长的新技术。

Dynamic characteristics of ultrasonic microbubble at low frequency and its biological effects

Based on the Lagrangian equation with dissipation function,the motion equa- tion of a microbubble with shell is obtained,and the dynamic characteristics of microbub- ble with shell in free space are studied.It shows that the inner and outer maximum radii of the microbubble increase when the acoustic pressure and its initial radius increase,as well as when the ultrasonic frequency decreases.A new forward Mie scattering technique for measuring the bubble radius with laser wavelength is developed.The injuries of micro- blood vessel in a tumor of a living animal were observed in real time by a stereo microscope system.It shows that:(1)The micro blood-vessel of tumor is embolized by thrombus which is formed when the vessel is injured by its periodical expanding and constricting un- der the action of a microbubble radiated with ultrasound,and the tumor growth is lowered. (2)The VEGF of the micro-blood vessel and the tumor cell can be damaged by microbub- ble combined with low frequency ultrasound,the regeneration of micro-blood vessel and tumor being reduced.Therefore it is necessary to develop the technique of microbubble combined with low frequency ultrasound.