Ultrasonic Nano-imaging of Vascular Endothelial Cell

为了对细胞进行精确成像，在电子扫描显微镜和带有荧光技术的激光扫描显微镜中需要进行抗体传感等前处理。无前处理的细胞非接触式纳米成像有望在各种条件下重复测量。本研究的目的是开发一种纳米成像系统，该系统可以用高频超声测量细胞的声速、衰减和声阻抗。此外，为了证明该系统在细胞生物力学测量中的有效性，我们比较了细胞和细胞骨架如肌动蛋白细丝或微管蛋白的声学性质的分布。通过高速机械开关产生脉冲宽度为2 ns的电脉冲直接输入超声换能器。脉冲响应用数字示波器进行分析。成像系统采用两台微机板控制的伺服直线电机进行x轴和y轴扫描。整个系统由一个工作站控制，两分钟内完成300×300点的数据采集。在频域中分析了试件表面反射与试件与玻片界面的干涉。建立了计算试件厚度和声速的算法，最后显示了定量声速分布的二维图，并用肌动蛋白细丝染色、电阻抗测量和纳米成像系统研究了肺血管内皮细胞的降温效果。结果表明，该系统可用于细胞生物力学的研究。

For precise imaging of cells, pre-treatments such as antibody sensing are needed in electron scanning microscopy and laser scanning microscopy with fluorescence technique. Non-contact nano-imaging of cells without pre-treatment is anticipated for repeated measurements under various conditions. The objective of the present research is to develop a nano-imaging system that can measure sound speed, attenuation and acoustic impedance of cells with high frequency ultrasound. Further, we compare the distribution of acoustic properties within a cell and cytoskeleton such as actin filaments or tubulin in order to prove the usefulness of the system in the measurement of cellular biomechanics.An electric pulse with the pulse width of 2 ns was generated by high speed mechanical switching was directly input into the ultrasonic transducer. The pulse response was analyzed by a digital oscilloscope. Two servo linear motors controlled by a microcomputer board were used for the scanning in both x- and y-axis of the imaging system. The total system was controlled by a workstation and 300x300 points data acquisition was done within two minutes. The interference between reflections from the surface of the specimen and the interface between the specimen and a glass slide was analyzed in frequency domain. The algorithm for calculation of the thickness and the sound speed of the specimen was established and finally two-dimensional mapping of quantitative sound speed distribution was displayed.Cooling effect of pulmonary vascular endothelial cells was investigated with actin filaments staining, electric impedance measurement and nano-imaging system. The results indicated the usefulness of the system for investigation of cellular biomechanics.