有机纳米材料在非线性光学成像中的应用

APPLICATION OF ORGANIC NANOMATERIALS IN NONLINEAR OPTICAL IMAGING

张子一

11849032

硕士

生物医学工程

吴长锋

2020-06-04

2020-07-08

哈尔滨工业大学

深圳

在微观尺度上对生物组织进行精准成像和治疗是现代生物医学和临床医学的重大需求。近年来荧光显微技术被广泛应用，但荧光发射过程往往伴随着荧光漂白、光化学毒性、荧光饱和等问题。为了解决上述问题，研究者们将目光着眼于非线性光学成像技术。二次谐波是非线性光学的一个分支，其产生过程不涉及能量吸收，规避了荧光染料的荧光发射过程带来的上述问题；并且在生物成像时，使用近红外二区光进行激发，有较深的生物组织穿透深度。因此，发展二次谐波成像是当前生物光学成像领域迫切的需求。为了增加图像的分辨率和对比度，使用二次谐波纳米探针对活细胞进行标记是目前通用的方法。近年来，大量的无机材料被制备成二次谐波探针，然而考虑到生物相容性、靶向标记能力和代谢特性等，无机探针后续应用潜力不足以与有机探针相比。为了使二次谐波成像成为一种有吸引力的工具，我们发展了RH237、DANS有机纳米晶作为二次谐波探针，应用于活细胞的二次谐波成像。通过纳米晶的制备，能够增加有机分子排列的有序性，提高纳米材料的极化率，增高二次谐波的信号强度。使用再沉淀的制备方法进行有机纳米晶的制备，通过调节包裹基质、投料顺序、有机分子和包裹基质的质量比，发展出一种普适性的用于制备二次谐波有机纳米晶的方法。对制备得到的有机纳米晶进行粒径、形貌、吸收-发射光谱、非线性光学性质等一系列表征。有机纳米晶的结构不仅增加了二次谐波信号，而且通过聚集诱导猝灭效应大大降低了荧光发射信号。有机纳米晶应用于二次谐波生物成像，实验对象为人乳腺癌细胞。采用共孵育的方式，将有机纳米晶胞吞至细胞内。在多光子显微镜下，进行活细胞的非线性光学成像研究。在二次谐波的接收通道内，观察到明亮且易于识别的信号；在其他通道内（包括双光子荧光发射接收通道），观察不到信号或仅有微弱信号。实现了将有机纳米晶应用于活细胞的二次谐波成像，拓展了非线性光学成像的介质材料制备方法和性质调控手段，为二次谐波组织深度成像研究及二次谐波激发光动力治疗的研究奠定坚实的基础。

Accurate imaging and treatment of biological tissues at the microscopic scale is a major need in modern biomedical and clinical medicine. Fluorescence microscopy has been widely used in recent years, but the fluorescence emission process is often accompanied by problems such as fluorescence bleaching, photochemical toxicity, and fluorescence saturation. To address these issues, the researchers have set their sights on nonlinear optical imaging techniques. Second harmonic generation (SHG) is a branch of nonlinear optics whose processes do not absorb energy, circumventing the aforementioned problems posed by the fluorescent emission process of fluorescent dyes. And in SHG bioimaging, the tissue is pumped with near-infrared two-zone light with a deeper penetration depth. Therefore, the development of SHG imaging is an urgent need in the current field of bio-optical imaging. In order to increase the resolution and contrast of the images, the use of SHG nanoprobes to label living cells is the current common method.In recent years, large amounts of inorganic material have been prepared as SHG probes. However, considering the biocompatibility, targeting marker capability and metabolic properties, the potential for subsequent application of inorganic probes is not sufficient to compare with organic probes.In order to make second harmonic generation imaging an attractive tool, we developed RH237, DANS organic nanocrystals as SHG probes to be applied to imaging of living cells. The structure of nanocrystals can increase the orderly arrangement of organic molecules, improve the polarization rate of nanomaterials and increase the SHG signal. The preparation was carried out using the re-precipitation method, and a universal method for the preparation of organic nanocrystals with SHG properties was developed by adjusting the type of wrapping matrix, the feeding order and mass ratio of organic molecules to wrapping matrix. The prepared organic nanocrystals were characterized in a series of ways such as particle size, morphology, absorption-emission spectra, and nonlinear optical properties. The structure of the organic nanocrystals not only increases the SHG signal, but also greatly reduces the fluorescence emission signal by aggregation-caused quenching effect. Organic nanocrystals applied to SHG bioimaging of human breast cancer cells. The organic nanocytes were swallowed into the cells by co-incubation. Nonlinear optical imaging studies of living cells under a multi-photon microscope.In the SHG receiving channel, a bright and easily identifiable signal is observed; in other channels (including the two-photon fluorescence emission receiving channel), no signal or only a faint signal is observed. In this dissertation, the application of organic nanocrystals to SHG imaging of living cells is realized, which expands the method of preparation of media materials and property regulation for nonlinear optical imaging, and provides a solid foundation for the future research of SHG imaging with deep tissue penetration and SHG excited photodynamic therapy.

二次谐波 非线性光学 有机纳米晶 生物成像

second harmonic generation non-linear optics organic nanocrystal bioimaging

中文

联合培养

南方科技大学

张子一. 有机纳米材料在非线性光学成像中的应用[D]. 深圳. 哈尔滨工业大学,2020.