Applications Of Nanoparticles In Cell Imaging And Determination Of Toxic Substances In The Environment

Owing to the good electrical properties, optical properties, magnetism and so on, nanoparticles have been widely applied in the the fields of environment analysis, food determination, bio-chemical analysis, cell imaging, catalysis, etc. So, in this thesis, based on the special properties of nanoparticles with cells and biomolecules, we investigate the application of nanoparticles in cell dark-field light scattering imaging and determination of toxic substances in environment such as melamine and Hg2+as follows,1. A facile solution-phase synthesis route of highly uniform Cu2O nanospheres (Cu2O NPs) in one step was developed and the prepared nanoparticles scattter pure blue light. We applied them as an optical probe for live cell imaging by dark-field microscopy. The transferrin-conjugated Cu2O NPs can get into the the human bone marrow neuroblastoma cells and show strong pure blue light in cytoplasm maybe owing to the receptor-mediated endocytosis. Cu2O NPs can also act as a probe for configuration of proteins leading to the local structural alteration of proteins.2. Including adenine, guanine, cytosine and thymine, only thymine of four DNA bases can form triple H-bonds with melamine. Single-stranded (ssDNA) can adsorb onto the surfaces of AuNPs in order to make nanoparticles well-dispersed, however when the cross-linking molecules exit, they can react with DNA and lead to the distance of AuNPs decreasing. On the basis of this, we present a new and simple sensitive plasmon resonance light scattering (PRLS) method for melamine in milk products with polyTn-stabilized AuNPs. Melamine in the range of 80 nM-1000 nM could be selectively detected with the linear equation of△IPRLS=-11.2+141.0 c (melamine, nM), the correlation coefficient (r) of 0.9905 and the limit of determination (LOD) of 20 nM. It can also achieve visual detection without any instrumentation or complicated design.3. The amalgamation process of cetyltrimethylammonium bromide (CTAB)-coated gold nanoparticels (AuNPs) from spheric NPs into erose stone-like NPs in the presence of Hg (Ⅱ) was investigated by PRLS spectra, plasmon resonance absorption (PRA) spectra and scanning electron microscope (SEM). We also confirm the surface coverage of mercury occurs indeed in the AuNPs solution by X-ray photoelectron spectroscopy (XPS). The color changes from red to orange to yellow going with the formation of Au-Hg amalgam and it can develop a simple colormetric determination of Hg2+.4. Mutiple-walled carbon nanotubes (MWCNTs) have the property of effectively quenching the fluorescence. ssDNA can wrap onto the surface of MWCNTs, while dsDNA can not. In this theory we develop a fluorescence determination of Hg2+ on the basis of T-Hg-T. In the optimum condition, Hg2+ in the range of 0.2μM-0.9μM could be selectively detected with the linear equation of IF=-18.7+700.9 c, the correlation coefficient (r) of 0.9860 and the limit of determination (LOD) of 0.02μM.