2021/02/22
Tokyo Institute of Technology
Keio University
Osaka University
Japan Science and Technology Agency
A research group including Hitoshi Ishiwata, a researcher at the School of Engineering, Tokyo Institute of Technology (also a JST PRESTO researcher); Hiroshi Watanabe, a Project Lecturer at the Graduate School of Science and Technology, Keio University (and a member of the Quantum Computing Center); and Shinya Hanashima, an associate professor at the Graduate School of Science, Osaka University, has succeeded in measuring the dynamics of phospholipids that constitute a lipid bilayer (cell membrane) only 5 nm thick, using diamond as a sensor. More than 70% of cellular responses to drugs such as anesthetics begin in a micro-region of about 5 nm on the outer side of the cell, known as the cell membrane. Therefore, to elucidate the principles of cellular drug responses, which are currently determined statistically, it is essential to develop a cell diagnostic technology that can analyze this micro-region with high sensitivity and in a label-free, or "as-is," manner.
The research group focused on a technique called nano-NMR, which uses diamond nitrogen-vacancy centers (hereafter, NV centers). NV centers, composed of nitrogen and defects in diamond, are attracting attention as nano-quantum sensors for precisely measuring biological phenomena, such as measuring the temperature inside a cell with a precision of less than 1°C. The most significant feature of this sensor is its size (approx. 1 nm), which allows for high-sensitivity quantum measurements at a distance of 10 nm or less from the observation target. Measurements near the target enable the measurement of the magnetism (nuclear spin) of substances within a limited micro-region (approx. 6 nm 3 ) very close to the sensor surface. To measure the nuclear spins of phospholipids moving in and out of a thin lipid bilayer mimicking a cell membrane, the group established a technique to form a lipid bilayer on a thin, film-like sensor. By performing quantum measurements within a detection range of 10 nm or less from the sensor surface, they successfully measured the diffusion coefficient, which indicates the dynamics of phospholipid molecules within the lipid bilayer.
Unlike conventional biological measurements that use phospholipid molecules artificially modified with fluorescent molecules, the nano-NMR technology developed in this study can measure the dynamics of phospholipid molecules in the cell membrane as they are, with high sensitivity and in a label-free manner. This is expected to lead to the elucidation of the mechanisms that control phospholipid distribution and dynamics, and to cell diagnostic technologies for investigating the relationship between phospholipid transport and disease.
This research was published in the online Early View edition of the German scientific journal *Advanced Quantum Technologies* on February 19 (local time). It is also scheduled to be featured on the cover of the journal's Issue 4, 2021 (to be published in April 2021).
For the full press release, please see below.