基质刚性影响声孔效应介导的单细胞基因转染

实验研究了基质刚性对单细胞质粒DNA转染效果的影响。实验采用高声压短脉冲(0.45MPa,10μs)条件的超声对培养在不同硬度凝胶基质(软的凝胶基质：0.2kPa,硬的凝胶基质：40kPa)上的力学敏感细胞NIH 3T3进行质粒DNA转染实验。实验结果表明,培养在硬的凝胶基质上的细胞,质粒DNA转染效率明显高于培养在软的凝胶基质上的细胞。进一步对质粒DNA进行荧光示踪可知培养在不同刚性基质上的细胞导入质粒DNA的方式不同。当细胞被培养在硬的凝胶基质上时,通过声致穿孔产生的小孔进入细胞内的质粒DNA更多,而培养在软的凝胶基质上的细胞,更多的质粒DNA可以通过非声致穿孔作用,例如内吞方式导入细胞。 细胞骨架蛋白分布规律表明,硬的凝胶基质上培养的细胞内有更多的F肌动蛋白微丝,可以更好地支撑起细胞的铺展形态,相对不容易发生内吞作用。而软的凝胶基质上培养的细胞内F肌动蛋白则更多以球形状态存在,细胞形貌骗向圆形,此时更容易发生胞吞作用。     

Ultrasound Microbubbles Enhance the Efficacy of Insulin-Like Growth Factor-1 Therapy for the Treatment of Noise-Induced Hearing Loss

The application of insulin-like growth factor 1 (IGF-1) to the round window membrane (RWM) is an emerging treatment for inner ear diseases. RWM permeability is the key factor for efficient IGF-1 delivery. Ultrasound microbubbles (USMBs) can increase drug permeation through the RWM. In the present study, the enhancing effect of USMBs on the efficacy of IGF-1 application and the treatment effect of USMB-mediated IGF-1 delivery for noise-induced hearing loss (NIHL) were investigated. Forty-seven guinea pigs were assigned to three groups: the USM group, which received local application of recombinant human IGF-1 (rhIGF-1, 10 µg/µL) following application of USMBs to the RWM; the RWS group, which received IGF-1 application alone; and the saline-treated group. The perilymphatic concentration of rhIGF-1 in the USM group was 1.95- and 1.67- fold of that in the RWS group, 2 and 24 h after treatment, respectively. After 5 h of 118 dB SPL noise exposure, the USM group had the lowest threshold shift in auditory brainstem response, least loss of cochlear outer hair cells, and least reduction in the number of synaptic ribbons on postexposure day 28 among the three groups. The combination of USMB and IGF-1 led to a better therapeutic response to NIHL. Two hours after treatment, the USM group had significantly higher levels of Akt1 and Mapk3 gene expression than the other two groups. The most intense immunostaining for phosphor-AKT and phospho-ERK1/2 was detected in the cochlea in the USM group. These results suggested that USMB can be applied to enhance the efficacy of IGF-1 therapy in the treatment of inner ear diseases.     

Finite element modeling of acoustic scattering from an encapsulated microbubble near rigid boundary

This article proposes a finite element model (FEM) for predicting the acoustic scattering from an encapsulated microbubble near rigid boundary. The validity of the model is first examined by comparing the acoustic nonlinear response of a free microbubble with that obtained by the Church model. Then this model is used to investigate the effect of the rigid boundary on acoustic scattering signals from microbubble. The results indicate that the resonance frequency decreases while the oscillation amplitude increases as the microbubble approaches the rigid boundary. In addition, the fundamental component of the acoustic scattering signal is enhanced compared with that of the free microbubble.     

Difference-frequency ultrasound generation from microbubbles under dual-frequency excitation

The difference-frequency (DF) ultrasound generated by using parametric effect promises to improve detection depth owing to its low attenuation, which is beneficial for deep tissue imaging. With ultrasound contrast agents infusion, the harmonic components scattered from the microbubbles, including DF, can be generated due to the nonlinear vibration. A theoretical study on the DF generation from microbubbles under the dual-frequency excitation is proposed in formula based on the solution of the RPNNP equation. The optimisation of the DF generation is discussed associated with the applied acoustic pressure, frequency, and the microbubble size. Experiments are performed to validate the theoretical predictions by using a dual-frequency signal to excite microbubbles. Both the numerical and experimental results demonstrate that the optimised DF ultrasound can be achieved as the difference frequency is close to the resonance frequency of the microbubble and improve the contrast-to-tissue ratio in imaging.     

石英毛细管椭球微气泡模式特性及传感技术

利用有限元数值分析方法研究了椭球状石英毛细管微气泡回音壁模式特性及其折射率传感性能.计算分析了不同半径与内壁厚度情况下空芯和液芯椭球形微气泡模式特征,包括品质因数、有效折射率和能量比等,并探讨了微气泡在高灵敏度和高分辨率折射率传感方面的应用潜能.研究结果表明微气泡膨胀至350μm,且内壁厚度为1μm时分辨率和灵敏度最佳;在该厚度范围附近,微气泡分辨率不会因为半径尺寸的改变而发生太大变化;二阶径向模具有较高品质因数,其灵敏度略高于一阶基模,且使用二阶径向模可降低在制造时对结构壁厚控制精度的要求,可用于实际传感应用中.研究结果对微气泡的进一步实验研制具有理论参考价值.     

超声药物释放空化动力学行为研究

以直径1 μm的脂质体为空化研究对象,从修正的Rayleigh空化方程入手,研究机械系数(MI)对300 kHz和1 MHz超声作用时空化效应的影响。脂质体的药物释放以超声作用前后脂质体中钙黄绿素的荧光强度为量度。模拟结果表明:在微泡振荡过程中,由超声波驱动产生的负向最大泡壁运动速度促使微泡半径从最大快速减小接近于零,微泡积聚到最大能量。对于300 kHz和1 MHz的激励超声,存在一个拐点(MI)值,当MI小于接近0.4时,1 MHz微泡半径变化幅度强于300 kHz;当MI>0.4时,300 kHz微泡半径变化幅度强于1 MHz。这一结果预示在此范围内,300 kHz的药物释放效果好于1 MHz。本研究为超声空化效应研究及超声药物释放应用提供了理论依据。     

超声联合微泡增强细胞内药物递送的研究进展*

超声联合微泡介导的细胞内药物递送是通过微泡的声空化与细胞的相互作用而实现的。作为一种非侵入式的、非病毒的、具有靶向性的、可在成像技术引导下的药物递送技术,超声联合微泡在临床应用上具有独特的优势。该文围绕超声联合微泡实现药物递送的发生机理,从微泡的声学动态响应、细胞响应、细胞外物质进入细胞的动态过程及临床试验进展4方面对超声联合微泡增强细胞内药物递送技术近年来的发展进行综述,并就机理性研究未来的发展提出了建议和思考。     

水下减阻技术研究综述

在简要回顾早期减阻研究的基础上,对现有典型水下湍流减阻技术进行了较深入地分析.重点介绍了脊状表面减阻、微气泡减阻和疏水/超疏水表面减阻的研究现状.分别从实验研究和理论研究两方面对其进行了阐述,并着重强调了各自的减阻机理. 此外,还简要介绍了柔顺壁面减阻、壁面振动减阻等其它减阻技术.展望了水下减阻技术今后的研究重点及其应用前景.      

非球形包膜微泡近场局部高压研究

基于流体力学,导出了超声驱动下的非球形包膜微泡的外部流体压强的解析表达式.数值模拟表明,虽然包膜微泡的非球形状对远场流体压强没有明显影响,但会造成近场局部位置有极大的流体压强,其明显高于同等条件下的球形包膜微泡周围相应位置上的流体压强.这一现象对包膜微泡的实际应用,如强超声治疗、靶向给药和细胞微穿孔等有着重要的意义.随着驱动频率向包膜微泡本征频率的靠近或微泡偏离球形程度的增大,所产生的近场局部高压也越大.     

The motion of microbubbles in a forced isotropic and homogeneous turbulence

We have studied the concentration distribution of microbubbles in forced isotropic turbulence. An initially uniform concentration field is shown to evolve to a highlyintermittent orspotty concentration distribution at long time due to the interactions of microbubbles with small-scale, intense, and coherent flow vortical structures. The maximum bubble concentration can be as large as 3,000 times the mean concentration and the local accumulations occur preferentially in the regions of high flow vorticity and low flow pressure. A quantitative measure of global nonuniformity in the concentration field is used to confirm that the preferential accumulation does follow Kolmogorov scaling, as opposed to the large-scale scaling commonly used for dispersion quantification.