Simulating Life: Breakthroughs in Non-Living Materials

Researchers in Irkoma's lab have discovered a new process that uses fuel to control non-biological matter, similar to the function of
living cells.
This reaction cycle can be easily applied to a wide range of materials, and its rate can be controlled, which is a breakthrough
in the emerging field of such reactions.
This discovery is a step towards soft robotics; Soft machines
that can sense what is happening in the environment and react accordingly.
The chemists published their findings in
Nature Communications.


Chemist Rienk Eelkema and his team sought to mimic nature, specifically the chemical reactions
in living cells that fuel the control cells.
Ilkoma explains that there is a
limited toolbox for reactions that drive non-biological materials in the same way.
So far, only about five types of reactions have been widely
used by researchers.
These reactions have two major drawbacks: their rates are difficult to control, and they only act
on a specific group of molecules.
Eelkema and first author Benjamin Klemm, a doctoral candidate, have discovered a novel type of reaction whose reaction rate can be efficiently controlled, and that is also applicable to a wide range of materials
.


"The essence of the reaction cycle is that it can switch
between uncharged and charged particles by adding chemical fuels," explains the swelling gel
Ilkoma.
" "This allows us to charge materials and thus change the structure of these materials, because equal charges repel each other and different charges attract
each other.
" The type and quantity of fuel determines the rate of reaction, and therefore the time of the charge and the existence of
a particular structure.
For example, the researchers used their reaction cycle to charge the hydrogel, after which the charges repel each other and the gel begins to expand
.


The cycle of soft robotic
chemical reactions could be useful for making soft robots: small devices as soft as our skin and tissues that can perform specific functions
.
"Soft robots already exist, such as particles
controlled by external magnetic fields or electric fields.
But at the end of the day, you want the robot to be able to control itself: see for itself where it is, what's going on, and then react accordingly," Ircoma said
.
You can program our loop into a particle in advance, then leave it alone, and once it encounters a signal, it will perform its function
independently.


Eelkema's next step is to connect this process to the environment by adding signal processing: "For example, a polymer particle might contain some components
of such a cycle.
This cycle is completed when it encounters the last part of the reaction, for example, as a signal
of decomposition or expansion.
"

Definition
of life: Cells of humans or other living beings need energy to perform a variety of functions: to move, sense what is happening, or divide.

"That's why we humans need to eat
," Ircoma explains.
"The connection between energy and function occurs through chemical reactions, which is the definition of
life.
It enables cells to control when and where
structure formation and processes occur for a limited amount of time.
”

In contrast, non-biological materials can exist forever and function
without an energy supply.
Until a decade ago, there was no process that could use chemical fuels to drive interactions
between non-biological materials.
Eelkema: "We introduced this technology in Delft and a few other places, and since then there has been an explosion in the field
.
"