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扫描探针显微镜生物成像研究与光镊的FDTD模拟

Scanning Probe Microscopy Imaging of Biological Origin and FDTD Simulation of Optical Tweezers

【作者】 孙伟

【导师】 潘石;

【作者基本信息】 大连理工大学 , 光学工程, 2006, 博士

【摘要】 本文描述了扫描探针显微镜在生物领域的应用和光镊的数值模拟研究。对于前者,阐述了原子力显微镜(AFM)对生物样品的成像研究,原子力与光子扫描隧道组合显微镜(AF/PSTM)的实验操作及其对各种样品的成像,特别是生物样品的成像。对于后者,探讨了时域有限差分法在光镊理论研究中的应用。 扫描探针显微镜是对固体表面进行高分辨研究的工具。原子力显微镜由于对样品的导电性没有特殊要求,并且能在接近生理条件下测量活的生物样品,从而成为生物领域的重要研究工具。本文通过对变形杆菌、狗肾上皮细胞和流感病毒的原子力显微镜成像研究,说明了原子力显微镜对临床医学和环境科学的应用。在对狗肾上皮细胞成像时,观察到细胞表面的小孔凹陷和突起,并获得了细胞膜表面细胞被(糖萼)的结构。在对流感病毒成像时,观察到了病毒表面的糖蛋白突起。 原子力与光子扫描隧道组合显微镜结合了原子力显微镜与光子扫描隧道显微镜的功能,能够在获得原子力显微镜形貌和相位图像的同时,通过对称照明样品,减少了原有光子扫描隧道显微镜所存在的假象;通过图像分解,可以获得样品的透过率和折射率图像。本文探讨了原子力与光子扫描隧道组合显微镜的实验操作,即如何具体实现原子力显微镜与光子扫描隧道显微镜的功能。文章通过对各种样品成像,验证了原子力与光子扫描隧道组合显微镜的功能。论文探讨了原子力与光子扫描隧道组合显微镜在生物领域的应用,揭示出它也能成为生物应用的重要研究工具。特别是在对海湾扇贝雄性生殖腺切片成像时,不仅观察到了海湾扇贝精子切片的表面形貌,通过光子扫描隧道显微镜透过率和折射率图像,还观察到精子头部细胞核内的精细结构。 光镊是利用光的辐射压来研究微观及介观粒子的工具。光镊能对生物样品进行非侵入式微操作。本文利用光镊对酵母菌细胞进行了捕获与操作。 光镊的理论是不完备的,特别是对于微米尺度(光波长)的粒子,至今尚没有较好的理论来描述。本文用三维时域有限差分法,探讨了微米尺度粒子所受的光辐射压力。光辐射压力由Minkowski电介质中的动量转换推出,入射聚焦光场用Richards-Wolf散射场理论来确定。计算所得的辐射压力与实验结果非常符合。 论文的研究结果表明: (1) 用AFM对生物样品成像,可以得到样品表面精细结构的信息;用自行研制的AF/PSTM不仅可以得到表面形貌,还可以得到生物体内部的结构信息。以AFM为基础的显微成像工具在生物领域具有广阔的应用前景。

【Abstract】 This thesis describes the biological applications of scanning probe microscopy (SPM) and the study of the optical trapping theory. For the former, biological imaging study of atomic force microscopy (AFM), atomic force/photon scanning tunneling microscope (AF/PSTM) operating, and biological imaging of AF/PSTM are elucidated. For the later, application for the optical tweezers theory using the finite difference time domain (FDTD) method is discussed.Scanning probe microscopy is one of powerful techniques studying the solid body surface with high spatial resolution. AFM, overcoming the limitations in imaging non-conducting samples, and allowing measurements of native biological samples in physiological-like conditions, becomes an important tool to the study of samples of biological origin. This thesis illustrates the clinical and environmental researches of atomic force microscopy, utilizing AFM imaging of proteus, canine renal epithelial cell and influenza viruses. In the AFM images of canine renal epithelial cell, the granules and the hole on the cell surface are shown, and the structure of glycocalyx on the cell membrane is obtained. In the AFM images of influenza viruses, the glycoprotein protrusions on the virus surface are shown.Atomic force/photon scanning tunneling microscope which combines AFM and photon scanning tunneling microscope, can implement the AFM imaging, and eliminate the spurious image with two-beam symmetric illumination system. With the method of separating image, the transmittivity and refractive index images of sample are obtained using AF/PSTM. In this thesis, the operating of AF/PSTM is discussed, that is how to perform the functions of AFM and PSTM imaging simultaneously. The function of AF/PSTM is validated by imaging research of a variety of samples. Biological applications using AF/PSTM are studied, and it is shown that AF/PSTM is one of powerful techniques in the study of life science. Especially, in the AF/PSTM images of the spermary of reproduction system of Argotecten irrabians, the ultramicroscopic structures of the sperm karyon is shown through transmissivity and refractive index images, while the its topography is obtained.Optical tweezers is a term describing the manipulation of microscopic and mesoscopic particles using the light radiation pressure force. Non invasive manipulation of biological

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