【作者】 李刚；

【导师】 唐建伟；

【作者基本信息】 华中科技大学 ， 光学， 2022， 硕士

【摘要】 干涉散射显微技术(Interferometric Scattering Microscopy,iSCAT)是一种基于光散射的成像方式,是无标记灵敏检测的强大工具。干涉散射显微镜通过引入额外的相干光束与颗粒的散射光发生干涉来放大微弱的散射信号,从而允许检测更小的散射颗粒。探测更小的纳米颗粒在生物学研究和工业产品检测上具有重要意义。利用干涉散射显微成像技术探测纳米颗粒时,背景散斑是限制探测灵敏度的主要因素。本文基于干涉散射显微成像技术开展了金纳米颗粒的静态和动态探测研究,针对静态和动态探测中的背景抑制、对比度增强、基底平整度影响等问题开展了如下研究:1.进行了对静态纳米颗粒的探测和背景散斑的研究。实验通过调制相减法去背景,来实现对玻片基底上和云母基底上的静态金纳米颗粒的探测。在空气环境中,在云母基底上探测到了直径为10 nm的静态金纳米颗粒,而在玻片基底上只能探测到直径为20 nm的静态金纳米颗粒。在水环境中,云母基底上探测到直径为5 nm的静态金纳米颗粒,而玻片上无法探测到。由于玻片比云母有更大的表面起伏,由起伏所产生的散斑背景更大,致使小的纳米颗粒信号淹没在玻片的背景散斑中而无法探测到。通过在光路中增加金属掩膜圆实现了对静态纳米颗粒的对比度的增强。2.进行了对水环境中动态纳米颗粒的探测研究。实验通过动态相减法去背景,在玻片基底和云母基底上均探测到了直径为5 nm的动态金纳米颗粒,并且比静态相减法所获得的同尺寸的纳米颗粒有更高的信噪比。通过在光学系统中增加金属掩膜圆实现了对水环境中动态纳米颗粒的对比度的增强。云母基底上和玻片基底上相同尺寸的动态纳米颗粒的信噪比基本一致。可见,基于动态相减法的动态纳米颗粒探测可将基底起伏导致的背景散斑高效去除,因此对基底的平整度要求低。本文开展的基于干涉散射显微成像技术进行静态纳米颗粒的探测研究,可应用于工业产品检测领域;开展的水环境中动态纳米颗粒的探测研究,在生物分子的探测及其动态过程的研究中具有应用前景。更多还原

【Abstract】 Interferometric scattering microscopy(iSCAT)is an imaging technology based on light scattering and is a powerful tool for label-free and sensitive detection.Interferometric scattering microscope amplifies the weak scattering signal by introducing an additional coherent beam to interfere with the scattered light from the particle,allowing detection of smaller scattering objects.Detection of smaller nanoparticles has important implications in biological research and industrial product inspection.Background speckle is the main factor limiting the detection sensitivity when using interferometric scattering microscope to detect nanoparticles.In this thesis,the static and dynamic detection of gold nanoparticles is carried out based on iSCAT,and the following researches are carried out on the background suppression,contrast enhancement,and the influence of substrate flatness on static and dynamic detection:1.The studies on detection of static nanoparticles and background speckle are performed.In the experiment,the detection of static gold nanoparticles on the glass substrate and mica substrate was realized by modulating the subtraction method to remove the background.In the air environment,10 nm gold particles were detected on the mica substrate,while only20 nm gold nanoparticles were detected on the glass slide substrate.In an aqueous environment,static 5 nm gold nanoparticles were detected on mica substrates,but not on glass slides.This is because glass slides have greater surface roughness than mica and thus have a larger speckle background caused by the undulations of the substrate surface,causing the small nanoparticle signal to be buried in the background speckle and not detectable.The increase in particle signal contrast is achieved by adding metal mask circles in the optical path.2.The studies on detection of dynamic nanoparticles and background speckle in water environment are also carried out.In the experiment,the background was removed by dynamic subtraction,and dynamic gold nanoparticles with a diameter of 5 nm were detected on both the glass substrate and the mica substrate,with a higher signal-to-noise ratios than nanoparticles obtained by static subtraction.The enhancement of dynamic nanoparticle contrast is achieved by adding metal mask circles.The signal-to-noise ratios(SNR)of nanoparticles of the same size on the mica substrate and the glass slide substrate are basically the same.It can be seen that the dynamic nanoparticle detection based on the dynamic subtraction method can effectively remove the background speckle caused by the roughness of the substrate,so the requirement for the flatness of the substrate is low.The detection research of static nanoparticles based on iSCAT carried out in this thesis can be applied to the field of industrial product inspection;the research on the detection of dynamic nanoparticles in the water environment carried out in this thesis has application prospects in the detection of biomolecules and the study of their dynamic processes.更多还原