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Study of Effects of Silver Ions and Silver Nanoparticles on Bacteria Based on Microscopy Imaging Techniques

Author: YangWenJuan
Tutor: WangKeMin
School: Hunan University
Course: Analytical Chemistry
Keywords: An atomic force microscope Dark field microscopy Silver ions Silver nanoparticles Antibacterial mechanism Biosynthesis
CLC: TB383.1
Type: Master's thesis
Year: 2009
Downloads: 110
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Abstract


The silver-based antimicrobial agent has good antibacterial properties, silver ions and silver nanoparticles as an antibacterial ingredient has been applied to clinical medicine and everyday life. In recent years, the overuse of antibiotics lead to the generation of various types of drug-resistant silver antimicrobial agents is a growing concern. But the silver ions and silver nanoparticles antimicrobial mechanism is not clear. Biochemical analysis methods provide important information to explain the antibacterial mechanism, and imaging techniques to improve the antibacterial mechanism provides intuitive morphological evidence. Characterization means the paper has a unique advantage in the imaging of biological samples using an atomic force microscope (Atomic force microscopy, AFM) and dark-field microscope two silver ions and silver nanoparticles on bacteria, bacterial surface characterization on the nanometer level ultrastructural changes provide important microscopic morphological information for the interpretation of silver ions and silver nanoparticles antibacterial mechanism. The main contents are summarized as follows: a bacterial silver ions based the AFM imaging technology research. Tapping mode AFM atmosphere characterized the role of silver ions Gram-negative bacteria E. coli and Gram-positive bacteria Staphylococcus epidermidis. The results show that: the E. coli surface silver ions vesicles, and gradually increased with the prolonged duration of action vesicles; irregular groove-like damage to the surface of Staphylococcus epidermidis, and the occurrence of a significant qualitative plasmolysis. Two bacteria of different injuries and their differences in the structure of bacterial wall. AFM imaging of the results obtained for understanding the relationship between structure and function of the cell surface has important significance, as well as the study of silver ions antibacterial mechanism provides valuable microscopic morphological information. 2, combined with the AFM imaging technology, and the dark-field microscopy imaging techniques to study the impact of silver nanoparticles on bacteria. Prepared by NaBH4 reduction of silver nanoparticles with a mean particle diameter of 10.3 nm, respectively, using tapping mode AFM atmosphere and dark field microscopy of the silver nano-particles role E. coli were characterized. The results show that: the silver nano-particles can be adsorbed on the surface of E. coli, especially concentrated in the two ends of the bacterial cells, causing serious bacterial two collapse and the surface a large number of irregularly shaped \interior. The Lysozyme control experiment further evidence of bacterial outer membrane structure destroyed by silver nanoparticles. The above results in the nano-level characterization of silver nanoparticles role of bacterial surface ultrastructure changes position silver nanoparticles role bacteria in the level of living cells at the same time positioning, provides for further research on the antibacterial mechanism of silver nanoparticles important information. 3, AFM-based research mulberry leaf reduction the synthetic antibacterial properties of silver nanoparticles. Mulberry synthesis of silver nanoparticles by transmission electron microscopy (Transmission electron microscopy, TEM), and dynamic light scattering (Dynamic light scattering, DLS), and characterized by means of the particles was found to have a good homogeneity and dispersibility, and an average particle diameter is 32.2 nm. The corresponding electron diffraction pattern of the results showed that the particles having a face-centered cubic crystal structure of the metallic silver. Fourier transform infrared spectroscopy (Fourier transform infrared, FTIR) results show that the mulberry leaves polyhydroxy ingredients and protein residues, respectively, play a role in reduction of silver ions and stable silver nanoparticles. The high salt concentration of the silver nano-particles exhibited a good stability. Turbidity method and AFM high-resolution imaging confirmed the antibacterial properties of the silver nanoparticles on the macro and micro levels, respectively.

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