Preparation Of Different Morphological Silica Nanomaterials And Detection Of Escherichia Coli O157:H7 Based On Fluorescent Silica Nanoparticles

As one of the important members of inorganic nanomaterials, silica nanomaterials have been widely applied in chemical, engineering and biomedical fields, with their extraordinary properties including simple synthesis, high stability, easy modification and good biocompatibility. Studies on shape-controlled preparation of silica nanomaterials are very necessary and important for the development of silica nanomaterials. In this paper, preparation of silica nanomaterials with various morphology has been studied, and the previously developed, fluorescent nanoparticles and SYBR Green I based two-color flow cytometry has also been further applied to detect E. coli. O157: H7.1. Shape-controlled preparation of silica nanomaterials by using poly-L-lysine as the template.We selected poly-L-lysine as the core material and prepared silica nanomaterials with various morphologies through TEOS hydrolysis in the reverse microemulsion. The influence of poly-L-lysine solutions with different pH and concentrations on the preparation of silica nanomaterials with various morphologies has been systematically examined. And by using circular dichroism to analyse the secondary structures of poly-L-lysine under different conditions, the relationship between the structure changes of poly-L-lysine and the different morphologies of silica nanomaterials has been further explored. The results showed that silica nanomaterials could be prepared into spherical, rod-like and the tube-shaped structures, respectively, by using the same template material poly-L-lysine. In addition, with Hela cells as the representative cell line, we initially examined whether the prepared silica nanomaterials with different morphologies could be taken up by cells. And the preliminary results showed that, after a 24h-incubation with Hela cells, all the three silica nanomaterials with different morphologies could get into the cells, and randomly distributed in the cytoplasm.2. Fluorescent nanoparticles and SYBR Green I based two-color flow cytometry (FSiNP@SG-FCM) for detection of E. coli. O157:H7A method using an improved two-color flow cytometric analysis by a combination of fluorescent silica nanoparticles and SYBR Green I has been developed for the rapid detection of E. coli O157:H7. Firstly, antibody of E. coli. O157:H7 was conjugated with RuBpy-doped silica nanoparticles. Then, E. coli. O157:H7 was specially labeled with antibody-conjugated RuBpy-doped silica nanoparticles, and subsequently stained with a nucleic acid dye SYBR Green I, followed by multiparameter determination with flow cytometry. This assay allowed for detection of as low as 2.8×10~3 cfu/ml E. coli. O157:H7 in buffer, which was decuple lower than the detection limit of the FITC-based conventional flow cytometry. This proposed FSiNP@SG-FCM method will be promising for rapid detection of E. coli. O157:H7 in water and food.