2021 Fiscal Year Research-status Report
Novel label-free tool for infections diagnosis based on Nano-Electro Optical Tweezers
| Project/Area Number |
20K12701
|
|---|
| Research Institution | Okinawa Institute of Science and Technology Graduate University |
|---|
Principal Investigator |
KOTSIFAKI Domna 沖縄科学技術大学院大学, 量子技術のための光・物質相互作用ユニット, 客員研究員 (70834117)
|
|---|
| Project Period (FY) |
2020-04-01 – 2023-03-31
|
| Keywords | Plasmonics / Optical Tweesers / Raman Spectroscopy / Bacteria |
|---|
| Outline of Annual Research Achievements |
In the second year, I have both investigated the role of SiC as substrate material as well as explored the best conditions to achieve single-bacterium trapping. Firstly, I have studied theoretically the enhancement of the electromagnetic field due to the presence of the SiC substrates and the temperature increase using Comsol Multiphysics software. I found that the theoretical temperature increase was only one degree/mW power. However, sticking effects of bacteria into the plasmonic nanostructures even with low incident trapping laser power were observed. A possible explanation for this discrepancy between theory and experiment is due to the adhesion layer that can absorb a greater fraction of the incoming infrared light leading to a significant increase in the local temperature. For this reason, a SiO2 substrate was employed to minimize the sticking effect and to trap effectively a single bacterium.
Using E. coli bacteria (Gram-negative), I have investigated the performance of the proposed platform by studying the survival and reproduction mechanism at the single-particle level as antibiotics have been added to the surrounding medium. I have noticed that the E. coli bacterium loses its mobility in a short time after the antibiotic is added. I have confirmed these experimental results by collecting the Raman signal of trapped single-bacterium using the plasmonic substrates. Despite the good performance of this platform for Gram-negative bacteria, its applicability to Gram-positive bacteria generates some obstacles that need more exploration.
|
| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
Up now the progress of the project is general smooth. However, some modifications have been done in order to follow the requirements of the project. First, I have replaced the SiC with SiO2 substrates after extensively theoretical and experimental study. I have evaluated the platform using Gram-positive and negative bacteria. However, the results for the Gram-negative bacteria should be confirmed using other techniques.
|
| Strategy for Future Research Activity |
My next plan focuses on studying the issues arising using Gram-negative bacteria, publishing the experimental results as well as writing the final report.
|
| Causes of Carryover |
The pandemic creates some issues that delay a lot the purchase process of consumables
|
Research Products
(2 results)
