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    Home > [materials] academician Tang benzhong of Hong Kong University of science and technology expands the new application of AIE materials: fluorescence, DFM, CT multimodal imaging

    [materials] academician Tang benzhong of Hong Kong University of science and technology expands the new application of AIE materials: fluorescence, DFM, CT multimodal imaging

    • Last Update: 2018-05-23
    • Source: Internet
    • Author: User
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    The demand of biological detection and clinical diagnosis has greatly promoted the development of imaging technology at the level of subcellular -, cellular and tissue As an imaging technology that can monitor biomolecules and biological processes in situ, fluorescence imaging technology has an irreplaceable position in related fields because of its high sensitivity However, for tissue and in vivo imaging, conventional organic fluorescent dyes are faced with the problems of insufficient tissue penetration depth, poor light bleaching resistance and low signal-to-noise ratio, so its application is limited to imaging of cells and animal epidermis Although inorganic nanoparticles such as quantum dots or upconversion materials have significant advantages over organic fluorescent dyes in terms of fluorescence quantum yield and photostability, their heavy metal elements have potential toxicity In order to apply the fluorescence imaging mode with high sensitivity to a wide range of fields such as in vivo imaging, it is necessary to introduce the imaging mode with high signal-to-noise ratio, spatial resolution and penetration depth For example, dark field imaging (DFM) based on the surface plasmon resonance effect of precious metals has unique advantages in signal-to-noise ratio, which can effectively avoid interference from the overall average effect in the single particle imaging of nanoparticles More importantly, CT imaging based on precious metals can provide high spatial resolution, three-dimensional scanning signal and enough tissue penetration depth The combination of fluorescent materials and noble metal nanoparticles will provide a multi-mode imaging tool that integrates sensitivity, spatiotemporal resolution and penetration depth Therefore, the combination of organic fluorescent dyes and inorganic nanomaterials not only has the advantages of both, but also can be used for multimodal imaging according to their different characteristics Figure 1 Preparation of silver AIE core-shell nanoparticles (aacsn) (photo source: J am Chem SOC., 2018, DOI: 10.1021/jacs.8b02350) Recently, academician Tang benzhong, Department of chemistry, Hong Kong University of science and technology, prepared a new type of silver AIE core-shell nanoparticles (aacsns, figure 1) and used it for multimodal biological imaging The fluorescence signal of traditional organic fluorophores will be seriously lost due to fluorescence resonance energy transfer (FRET) or electron transfer (ET) However, Tang's team found that under alkaline conditions, the AIE fraction with redox activity can reduce silver ions to silver nanoparticles, and the obtained silver nanoparticles can induce the AIE fraction at the same time Finally, the core-shell nanostructure composed of inorganic noble metal core and organic AIE shell was formed The new nanoparticles not only retain the aggregation induced luminescence effect of AIE molecules, but also have the plasma scattering characteristics of precious metals Moreover, the core-shell nanoparticles can be used for fluorescence, dark field (DFM) and computed tomography (CT) imaging This achievement was published in the Journal of the American Chemical Society (DOI: 10.1021 / JACS 8b02350) under the title of "redox active aiegen derived plasma and fluorescentcore @ shell nanoparticles for multimodality bioimaging" Fig 2 a) synthesis route of tpe-m2oh; b) spectral properties of aacsns before and after formation; c) XRD and TEM diagrams of aacsns (photo source: J am Chem SOC., 2018, DOI: 10.1021/jacs.8b02350) The author first synthesized AIE molecular precursor with methoxy group from 4,4-dimethoxybenzophenone and 4-bromobenzophenone (Fig 2A, 3) The AIE molecule containing phenolic hydroxyl group was obtained by removing methyl group from methoxy group with boron tribromide (Figure 2a, tpe-m2oh) After that, tpe-m2oh and silver ions were mixed in an alkaline solution (pH = 10.5), and the color of the solution quickly darkened (Fig 2b) Through the spectral test, it can be found that the discolored solution has strong UV absorption at 485 nm (Fig 2b), which indicates that there are silver nanoparticles in the solution In addition, the discolored solution also has obvious fluorescence emission at 650 nm (Fig 2b), which indicates the aggregation of tpe-m2oh in the solution In order to prove that there are indeed silver nanoparticles in the solution, the material was characterized by XRD (Fig 2C) It was found that there are indeed silver microcrystals in the prepared material, which was further proved by high-resolution transmission electron microscopy (HR-TEM) (Fig 2C) In addition, HR-TEM results also show that the core size of silver nanoparticles in core-shell structure is about 45 nm, while the thickness of AIE shell is about 20 nm Furthermore, the shell thickness can be precisely adjusted from 16 nm to 30 nm by adjusting the feed ratio, reaction time and temperature Figure 3 fluorescence and DFM dual-mode imaging (left, center) and fluorescence and CT dual-mode imaging (right) (photo source: J am Chem SOC., 2018, DOI: 10.1021/jacs.8b02350) of aacsns After understanding the basic structure and properties of this structure, the author studied its imaging power Due to the surface plasmon resonance characteristics of noble metal nanoparticles, the author speculates that this material can be used for fluorescence and DFM dual-mode imaging The results show that not only the blue highlights in DFM images can coincide with the red highlights in fluorescent images perfectly, but also they can correspond to the micro dots in the electron micrograph one by one (left in Figure 3) After that, the author studied the colloidal stability and toxicity of aacsns for the subsequent application of biological imaging The results showed that aacsns not only had good stability, but also had a great improvement in biocompatibility because silver nanoparticles were well dispersed by tpe-m2oh Then, the author tried the dual-mode imaging of aacsns in cells, and found that it has a good effect on fluorescence imaging and DFM imaging At last, the fluorescence and CT imaging of aacsns were carried out The results showed that the enhancement effect of aacsns on CT signal at 20 mg / ml was similar to that of commercial reagents, and there were clear fluorescence and CT signal in tumor area of mice All authors: Xuewen he, Zheng Zhao, Ling Hong Xiong, Pengfei Gao, Chen Peng, Rong Sheng Li, Yuxiong, Zhi Li, Herman H - Y sung, Ian D Williams, Ryan T K Kwok, Jacky W y Lam, Chengzhi Huang, Nan Ma, and Ben Zhong Tang
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