| Bio-imaging especially live cell imaging has received considerable attention not only as a research tool, but also in the prevention and early diagnosis of various diseases. Live cell imaging requires the size of the fluorescent dyes is small enough to enter the cells and then be visualized easily without affecting the normal metabolism behavior of the cells. However, organic fluorescent dyes are generally hydrophobic or even insoluble, which greatly limits their application in biological systems, and so far only a few kinds of organic fluorescent dyes have been used for bio-imaging, such as rhodamine and its derivatives. Because of such concern of hydrophobic problems, other attractive dyes, such as perylene with high quantum yield has been widely used in organic electroluminescence devices but not for bio-imaging. The intention of this paper is to prepare nanoparticles of such hydrophobic organic dyes in appropriate size, as the fluorescent dye nanoparticles are incubated with the cells for a sufficient time, they can be uptaken by the cells and then locate in the certain organelles, the cytotoxicity and live cell imaging function of the organic fluorescent nanoparticles will be studied for the purpose of providing a new effective bio-imaging method by using organic fluorescent nanoparticles.In this paper, N, N'-bis-(2,6-diisopropylphenyl)-1,6,7,12-tetrachloroperylene-3,4,9,10-tetracarboxylic acid diimide (PDI) was synthesized, and the PDI nanotubes were prepared within the nanopores of anodic alumina templates (AAO). The fluorescent properties of PDI nanotubes were investigated and its application in live cell imaging was investigated primarily. In addition, PDI/Ag/PMMA nanoncomposite was successfully prepared by using an in-situ polymerization method and its fluorescent property was also studied. The detailed works can be summarized as follows:1. PDI nanotubes were successfully prepared within the nanopores of AAO templates. The AAO template, with which the pore size and length can be tuned easily, was prepared in lab by aluminum electrochemical oxidizing. The morphology, structure and surface potential of the PDI nanotubes were characterized by using SEM, HRTEM and Zeta potential meter, respectively. The results indicated that the nanotubes were in an amorphous phase with negative surface potential, and they had an average outer diameter of about 60 nm, with the lengths ranging from several hundred nanometers to several micrometers. The optical properties of the nanotubes were measured by using UV-visible near-infrared spectrophotometer (UV-vis) and fluorescence spectrometer (PL), which indicated that the nanotubes were formed by head-to-tail J-aggregates. It is noteworthy the PDI nanotubes showed high fluorescent property. In order to observe its bio-imaging effect, HepG-2 cells were chosen to be incubated with the PDI nanotubes, it was found that large numbers of the nanotubes entered into the cells after 2 hours co-incubation and then the cells could be visualized obviously by fluorescent microscopy observation. Moreover, the cytotoxicity of the PDI nanotubes was evaluated by MTT assay and the results have demonstrated that the cell viability of the HepG-2 cells exposed to effective concentration (≤60μg/mL) of nanotubes for 72 h was still as high as 90%.2. Silver nanowires and nanoparticles had been prepared by polyol reduction in the presence of poly (vinylpyrrolidone). The morphology and structure of Ag nanowires and nanoparticles were characterized by using SEM, XRD and HRTEM. The results showed that both of them were highly crystalline, but the Ag nanowires had a maximum aspect ratio of 200, while the Ag nanoparticles had a size distribution ranging from 50 to 500 nm. PDI/Ag/PMMA nanocomposites were synthesized by means of in-situ polymerization. The structure and fluorescent property of the nanocomposites were investigated by using TGA, HR-TEM and the fluorescent microscopy. This initial work did not result in a direct surface modification of Ag nanoparticles by organic PDI molecules, but the research author has done deserves further studies.
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