| Cancer is one of the most critical threats to the health of human being. Recently, the incidence of cancer is increasing. Since born in the late1980s, nanotechnology has been in a stage of vigorous development. Nanomaterials have some unique properties, such as large specific surface area, a lot of reactive sites, high catalytic efficiency, strong adsorption capacity, good stability. With these advantages, nanomaterials are applied in many fields such as chemistry, biology, and medicine. Meanwhile, many new nanomaterial-based technologies and methods were developed for the study of the mechanism of the interaction between biomolecules, the mechanism of human disease research, and cancer early diagnosis and treatment. Therefore, detection of tumor cells combined with nanotechnology has become a research focus of scientists.Fluorescent silica nanoparticles have high fluorescence intensity, high stability, easily modified surface, excellent biocompatibility and their particle sizes are uniform, adjustable. These features make fluorescent silica nanoparticles suitable for the researches in many fields, such as immunoassay and biosensor. Gold nanoparticles also have many special features. For example in the UV-visible region it has strong and stable surface plasmon resonance absorption peak. Moreover their maximum absorption peak positions and FWHM are sensitive to the shape of the nanoparticles, the distance between particles, the solution dielectric constant factors, and the temperature. Because of these features mentioned above, they are widely used in analytical detection. Based on the backgrounds, the thesis further enrich and expand the application of fluorescent silica nanoparticles and gold nanoparticles in the life analysis, in particular the application of the detection of tumor cells. It also contributes to the clinical diagnosis and treatment of cancer with positive significance. The main contents of this thesis are as follows: Chapter One:IntroductionFirst of all, the research background, the traditional diagonostic methods, and the significance of tumor markers in tumor detection are introduced. Then, the chapter explains the significance of tumor detection based on the nanomaterials in detail. Lastly, we review fluorescent silica nanomaterials and gold nanoparticles in range from their synthesis, surface modification to biological applications in detail. Chapter Two:Phenylboronic Acid-tagged Fluorescent Silica Nanoparticles via Thiol-ene Click Reaction for Imaging Sialic Acid Expressed on Living CellsIn this chapter, fluorescent silica nanoparticles with phenylboronic acid tags via thiol-ene click reaction were developed for labeling sialic acid on the surface of living cancer cells. Firstly, fluorescent silica nanoparticles were prepared by reverse microemulsion. Then, phenylboronic acid was covalently modified on fluorescent silica nanoparticles by click reaction. In this chapter, fluorescent silica nanoparticles (FSNPs) with strong and stable emission at515nm were firstly prepared through a reverse microemulsion process, and then modified with highly selective phenylboronic acid (PBA) tags on their surface via an aqueous ’thiol-ene’click reaction. These nanoparticles had a hydrodynamic diameter of92.6±9.1nm, and a bright fluorescence signal, which is290times higher than that of a single dye molecule. Meanwhile, these PBA-tagged FSNPs were found very stable in aqueous solution as well as in cell culture medium, verified by TEM, XPS and zeta potential analysis. The over-expressed sialic acid (SA) on the membrane of living HeLa cells was visualized in situ by a confocal laser scanning microscopy, ascribed to the specific interaction between PBA and SA. Thus, the PBA-FSBPs showed a great potential in probing SA expressed on living cells with high selectivity and sensitivity. Chapter Three:Colorimetric Detection of Cancer Cells Based on Cyclic Enzymatic Signal Amplification and Conformation Alteration of Aptamer ProbeIn this Chapter, for the first time we discussed the combination of cyclic enzymatic signal amplification with conformation alterations of aptamer probe for colorimetric detection of tumor cells. Firstly,13nm gold nanoparticles and the DNA-modified AuNPs were prepared. Secondly, we achieved signal amplification and specific detection through cyclic enzyme digestion and conformation alteration of aptamer probe. The colorimetric results demonstrated that the aptamer probe-2had the most significant signal enhancement for the detection of cancer cells. Also, the optimum concentration of enzyme and time for this nicking reaction were selected as20U and90min, respectively. Under the optimal conditions, this colorimetric detection demonstrated that the linear response for target CCRF-CEM cells was102to104cells, with a detection limit of56cells. The calibration curve was A525/A610=1128+0.00562x Ccells. Because this colorimetric method is simple and sensitive, it provides a visual detection of tumor cells for cancer early diagnosis.
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