Fabrication Of Silicon Carbide Quantum Dots For Fluorescence Labeling Living Cells And Its Dynamic Tracing

Quantum dots (QDs) materials have attracted much attention all over the world due to their unique optical properties in the field of nano bio-technology such as fluorescent labeling, imaging and dynamic tracing, and so on. In recent years, more and more attention have paid for the cadmium QDs like CdSe, CdTe, CdS etc because of their cytotoxicity. It is necessary to develop a kind of QDs with low toxic or nontoxic and application in the biology field. Fortunately, silicon carbide quantum dots (SiC-QDs), as a new QDs with excellent optical properties and biological compatibility, have a development prospects of biology nano-materials.In the present works, a new kind of SiC QDs fabrication approach was developed and size, surface physicochemical characteristic of QDs can be easily controlled. The main works of this paper included:microstructure evolution in the process of SiC QDs preparing, effect of fabrication parameters on the optical properties, influence of SiC QDs surface chemical aspects to characteristic emission spectra, method of fluorescent Labeling living cells with QDs, the fluorescent stability of labeled living cells and tracing in vivo. Some novel results are listed as following:Firstly, the aqueous SiC quantum dots with some hydrophilic organic group conjuncting the surface was prepared by one step via chemical etching method. With (3-SiC nano-particles (100～500 nm) prepared via self-propagating combustion as raw materials, there are so many crystal defects (dislocation, vacancy and grain boundary) on the particles surface because of its formation characteristics (such as rapid response, cooling speed and formatting non-equilibrium crystallization conditions easily). The mixture chemical etchants with nitric and hydrofluoric acid can easily corrode the nano-particles into porous latticed-hollow structure without electricity due to their low corrosion activity. After deacidification, mechanical lapping, ultrasonic cavitations and tomographic clipping in ultra-gravity field, the non-cytotoxic labeling material of silicon carbide quantum dots were so prepared.Secondly, the hydrophilic organic group on the SiC QDs surface can be easily adjusted through regulating the components and concentration of mixture echants. With the ratio of V(HF):V(HNO3):V(H2SO4)=6:1:1, the sulfydryl (-SH) stability coupling on surface and high photoluminescence intensity of prepared SiC-QDs will be obtained. The results of optical characteristics indicated that the luminescence intensity of emission light with 450 nm wavelength reached the maximum value under 340 nm excitation wavelength so that the Stoks movement was 110 nm. According to the emission light of SiC-QDs, red-shift will occur with excitation wavelength increasing, while blue-shift will appear along decreasing the size of QDs under the same excitation wavelength because of their strong affinities with each other.Finally, through endocytosis for SiC-QDs, the living cells of Aureobasidium pullulans and Fusarium moniliforme were stably fluorescent labeled and long-term-distance imaging and tracing in vivo. The effect of phlorizin on the vegetation process of fusarium moniliforme was investigated and growth promotion action of phlorizin was so revealed. Infection process of labeled fusarium moniliforme to root system of apple tree were researched. The results indicated that, according to the Fusarium moniliforme Sheld, special infection epidermal cells to the outer root didn’t exist and the wound was not a necessary condition for firstly infecting.