| 研究実績の概要 |
The aim of this project is both to determine the type of a single-bacterium and to monitor its behavior using antibiotics. To reach this overall objective, in the first year the project was focused to optimize the plasmonic device and eliminate the convections effects that were generated under illumination conditions. Specifically, I have designed and fabricated an array of nanoholes on 50 nm gold thin film using a focused ion beam. I have characterized these plasmonic devices by collecting the absorption spectrum in deionized water to identify the plasmon resonance at 928 nm. This step is critical due to one can extract information about the changes of the resonance peaks when the bacterium will be trapped and simultaneously recognize its phenotype. Then, I have investigated the convections effects and the thermophoresis force generated by illuminating the plasmonic devices on- and off-resonance using as samples polystyrene particles with several diameters. The goal is to determine the laser power range in which prevents the bacterium photodamage and is sufficient to achieve trapping. I have concluded that using laser power less than 3 mW, a particle with a size comparable with the bacterium size can effectively transport to the trapping positions where can be trapped. Moreover, working off-resonance condition you can eliminate the phototoxicity effects allowing the bacterium to be alive for a long time at the trapping position. After this initial optimization of the plasmonic device, I am going to evaluate using E.coli bacterium.
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| 今後の研究の推進方策 |
My next plan focusing on bacteria study. For this purpose, I will choose a well-known bacterium such as E.coli as a sample and I will try to optimize the plasmonic device using real biological samples. I will investigate which are the best conditions to achieve single-bacterium trapping by investigating parameters such as laser power, trapping wavelength, polarization, etc. I will study also the growth, survival, and reproduction mechanism of the single bacterium at the trapping position, by changing the laser power and the trapping wavelength. Finally, I will try to integrate the plasmonic device with an external current in order to collect information about the bacterium antibiotic susceptibility.
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