分子コンピュータの概要
Hello everyone, SCIEN-SPOT is a podcast that shines a spotlight on the latest scientific technology
from Japan. Your host is REN from SCIEN-TALK. Today, I'd like to talk about the computer that
operates at the molecular level with individual molecules acting as computational units.
This incredible future device is being realized by a research group at Japanese university.
When you hear the word computer, what comes to mind? Likely, it's an electronic device
like a laptop or a smartphone, something palm-sized or larger. However, what we're
going to talk about today goes for beyond that conventional image. It's about a ultra-compact
computer that operates at the molecular level. Why do we need such tiny computers?
While conventional computers are incredibly powerful, they can't process information within
our bodies at the cellular level. For the delicate tasks like early disease detection
or delivering specific drugs only to the required location in our body, we need information
processing at a much more microscopic scale. To tackle this challenge, DNA computing has
garnered significant attention. DNA, as you know, is a blueprint of life carrying our genetic
ナノポア技術の役割
information. But researchers have discovered that by levelizing DNA's unique properties,
especially its sequence designability and specific complementary binding, it can be used
for logic operation and computational processing much like a programming language. Until now,
traditional DNA computing methods involved mixing many DNA molecules in a test tube
and utilizing their collective behavior for calculations. However, this approach made it
difficult to observe the real-time movements of individual molecules, limiting precise
information processing at the single molecule level. This is where nanopore technology comes in.
A nanopore is a tiny hole in a membrane. By capturing the electric signal generated when
molecules pass through it, it allows for highly sensitive real-time observation of
individual molecules like DNA and proteins. It's a powerful tool that literally lets
see molecular movements. The revolutionary device called SMOLU,
this means Single Molecular Logic Unit, developed by Professor Yuji Kawano's research group at the
Tokyo University of Agriculture and Technology. This device was made possible by combining the
nanopore technology and DNA computing that I just introduced, resulting in one of the world's
分子コンピュータの基本機能
smallest molecular computing devices embedded in the lipid membrane. This SMOLU can perform
a basic logic operation, an AND gate, at the molecular level, similar to what everyday
computers do. An AND gate means that a particular result is achieved only when both conditions A
and B are met. For example, imagine the security doors that only open if both the correct key
and the correct password are provided. So how does SMOLU achieve this AND gate functionality?
At the heart of this device is a Y-shaped, three-stranded DNA structure,
commonly called 3WJ DNA. This 3WJ DNA is engineered with a recognition site for two
different types of restriction enzymes, which are essentially molecular scissors that cut DNA at a
specific sequence. You can think of it like a single rope marked with spots where only scissors A
can cut, and other spots where only scissors B can cut. This Y-shaped DNA is securely fixed
inside a tiny pore called an alpha hemolysin nanopore. This nanopore is specifically suitable
for DNA detection. Furthermore, the entire SMOLU system, including this nanopore, is integrated
into the membrane of a giant amni-lamellar vesicle, which is an artificial cell-like
ナノポア技術とDNA論理ゲート
liposome made of a lipid-V layer, much like a natural cell membrane.
And now for the AND gate operation. Two types of these molecular scissors, the restriction enzymes
are introduced outside this liposome structure. The system is designed so that only when both
of these restriction enzymes act simultaneously on the Y-shaped DNA fixed inside the nanopore.
A specific DNA fragment is cleaved and released into the interior of this structure. If only one
or more enzymes act, this DNA fragment is not released. Once released, this DNA fragment then
reacts with other DNA components prepared inside this structure, triggering a DNA amplification
reaction. This amplification reaction is then visualized using fluorescent molecular levels.
This allows the researchers to optically confirm with their own eyes whether the molecular level
and operation was successfully performed, much like a light bulb turning on only when the correct
conditions are met. So this system holds immense significance because it enables the direct
observation and control of the computational functions of a single DNA molecule using
nanopore technology. This truly represents the realization of the smallest unit of molecular
分子論理回路の展望
computing. And while this research is still in its early stage, its potential is limitless.
The next steps aim to design even more complex molecular logic circuits or applying them to
multi-stage computational processes. And this technology is expected to lead to evolutionarily
medical or diagnostic applications. This includes highly sensitive detection of disease markers
by sensing environmental changes inside the outside cells, or even targeted drug release
systems that deliver precise amounts of medicines to specific locations in response to target
molecules. The future where tiny molecular-driven computers protect our health is steadily approaching.
That's all for today's SciencePod. This podcast is broadcasted every on weekday morning in
vast Japanese and English. I hope today's discovery has changed how you view the microscopic
world within us, even just a little. I'd like to listen to the podcast and post your notes and thoughts
with the hashtag SciencePod. See you next time!
