Research Of Fluorescence Labeling And Imaging Tracer For Living Cells Of Pathogenic Fusarium Oxysporum With Silicon Carbide Quantum Dots

Due to its serious impact on the production of crop and industrial crop, the development of livestock husbandry and human health, Fusarium has become the research focus of microorganisms, fungus, and ecologyand phytopathology and etc in domestic and abroad. At present, since the pathogenic mechanism of Fusarium wilt is still not clear, resulting in the unsatisfactory control efficiency; and using fluorescence tracing technique to investigate the pathogenic mechanism has become an industry consensus. Considering the fact that conventional organic fluorescent dyes and quantum dots materials fail to satisfy the need for longtime fluorescence tracing, it is imperative to develop new fluorescent dyes for living cells.The latest research discovered that due to its excellent optical property and good biocompatibility, SiC quantum dot is analternative for fluorescent labeled and long-term-distance imaging and tracing in vivo and new type of nanometer tracing biological materials to replace the conventional fluorescent dyes.Therefore, adopting nanometer homogeneous carborundum grain prepared by self-propagating, SiC-QDs with controllable granule size and surface physicochemical characteristic were prepared through controlling chemical etching, ultrasonic cavitations and tomographic clipping in ultra-gravity field. The main works of this paper included: the optical characteristics of SiC-QDs, relational influencing factors, surface physicochemical characteristic, the mechanism of marking quantum dots and the detecting methods, the fluorescent stability and long-term-distance fluorescent imaging tracing of pathogenic Fusarium, and the conclusion can be drew as follow:(1)The microstructure evolvement during the preparation of SiC-QDs and the effect of processing parameters on photoluminescence performance of SiC-QDs were investigated.As the result, the mutual correlation mechanism among the preparation techonology, particle size, and photoluminescence characteristic was established. The results indicated thatSiC-QDs photoluminescence intensity reached the maximum value when Hydrofluoric acid and nitric acid ratio was 3:1. The best time duration of ultrasonic treatment was 20 min to25min. The ultra-gravity field is an important influence factor on the size of SiC-QDs. The fluorescence color of SiC-QDs is closely related to the particle size and the excitation wavelength.(2)The crystal structure of SiC-QDs was analyzed via JADE 5.0 and Materials Studio6.0 to calculate and simulate the adsorption mechanism of surface functional groups. The results showed that SiC-QDs belong to the face-centered cubic crystal system(FCC, F-43m),and the final modified 3C-SiC unit-cell parameters are a=b=c=0.4348 nm and ?=?=?=90orespectively, and each unit cell satisfies the chemical formula of Z=4. –COOH, –OH, and functional groups on the surface of the SiC-QDs can develop stable chemical bonds and bond energy is 2.65 and 5.09 eV respectively. The density of states, electron density distribution and the bonding mechanism of the configuration after adsorption were also analyzed.(3)This paper researched on SiC-QDs fluorescent labeling and imaging and tracing methods of pathogenic Fusarium, and the result showed that SiC-QDs could achieve pathogenic Fusarium's tunable color fluorescent labeling(the excitation wavelength range was between 320 nm to 520 nm). Due to the character of non-poison and strong capacity of anti-photobleaching, SiC-QDs could also achieve long-term-distance imaging and tracing.The paper also did dynamic tracing in apple seedling root system infected by pathogenic Fusarium.