2018 Fiscal Year Annual Research Report
Anisotropic magnetic field effect imaging microspectroscopy: a technique to search cells for magnetic compass ability
| Project/Area Number |
17H03005
|
|---|
| Research Institution | The University of Tokyo |
|---|
Principal Investigator |
ウッドワード ジョナサン 東京大学, 大学院総合文化研究科, 教授 (80526054)
|
|---|
| Project Period (FY) |
2017-04-01 – 2020-03-31
|
| Keywords | 磁気受容 / ラジカル反応 / 磁場効果 / 磁場効果 / スピン化学 |
|---|
| Outline of Annual Research Achievements |
During the second year of this project, progress was made in experimental work, theoretical work and research outputs.
The original design of the microscope (constructed and employed during year 1) used the TIRF (Total Internal Reflection Fluorescence) principle based on knowledge gained from the existing literature. This year, we made progress in our theoretical kinetic simulations on spin effects on the fluorescence of single flavin adenine dinucleotide (FAD)molecules, which lead us to reevaluate our experimental approach. Our experimental work has thus focussed on redesigning our microscope to allow much higher excitation intensities to be achieved. As a result of the new design, magnetic field effects (MFEs) have been observed directly on the fluorescence of FAD at concentrations equal to the endogenous levels in human cervical cancer (HeLa) cells.
The previously proposed dual path camera / single photon detection system was successfully installed.
Our work on constraining radical pairs has continued and we have successfully immobilized quantum dots
(QD) using polymers and measured the fluorescence from single QDs.
One poster and five oral presentations were delivered in 2018. The first publication from this work was published in December 2018.
|
| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
Our microscope system is now providing robust data on MFEs in isotropic solution at sub-micromolar concentrations of flavins. We have observed the fluorescence of single molecules in solution and have some obtained some experimental evidence for single molecule fluorescence from FAD. Measurements have been made by employing an oscillating z-axis magnetic field during the observation of fluorescence decay kinetics.
We have successfully grown HeLa cells and recorded the fluorescence kinetics of endogenous flavins. At this point, having further optimized the optical arrangement since these measurements, we believe we can record signals with sufficient signal-to-noise ratios to make the investigation of spin effects in these cells a possibility.
Our experience has grown in preparing gel- and polymer-based samples for immobilizing radical pairs. We have some preliminary evidence of success in immobilizing single molecules of similar size to FAD. A new project student will be undertaking the design and preparation of these samples.
Our work on the kinetic simulation of spin effects on single molecule fluorescence from FAD is complete and our findings have been published. Mr. Ikeya has been studying the necessary theoretical background and use of Matlab / Spinach libraries to undertake future spin-dynamic simulations.
|
| Strategy for Future Research Activity |
We are currently studying a wide range of photochemical reactions in solution to characterize both the microscope and spin effects on flavins in solution where the effects of diffusion need to be included. Our high irradiation intensities have allowed us to observe small magnetic field responses in non-flavin systems which appear to be due to triplet-triplet annihilation processes. These effects will also be further investigated.
The next major set of measurements will focus on trying to observe anisotropic MFEs on immobilized flavins exploiting gel- and polymer-based approached. As well as allowing effects of magnetic field direction to be investigated, these experiments will allow us to optimize spin effects while minimizing molecular motion, which may also enable us to observe the first spin effects on single radical pairs.
The enhanced sensitivity of the microscope means that we can now begin MFE measurements on live HeLa cells and we will employ a number of techniques to increase the level of endogenous flavins in the cells to confirm any observed effects. If progress is substantial, we will begin undertaking cell-transfection experiments to introduce cryptochrome proteins to the cells.
Theoretical work will now move to detailed spin dynamic calculation of anisotropic MFEs in constrained flavins and hyperfine dependent effects in single radical pairs.
We will submit an experimental paper to a special edition of the Journal of Chemical Physics in September. Prof. Woodward will present the latest results at the International Spin Chemistry meeting in Russia in August.
|
Research Products
(7 results)
