Artificial muscles made of proteins

Date:
January 28, 2022
Source:
University of Freiburg
Summary:
A research team has developed a material made of natural proteins
that contracts autonomously.



FULL STORY ==========================================================================
Dr. Stefan Schiller and Dr. Matthias Huber from the University of
Freiburg's livMatS Cluster of Excellence have succeeded in developing
a muscle solely on the basis of natural proteins. The autonomous
contractions of the material, which the researchers presented in
the journal Advanced Intelligent Systems, can be controlled with
the help of pH and temperature changes. The movements are driven by a
chemical reaction that consumes molecular energy for this purpose. "Our artificial muscle is still a prototype," says Schiller. "However, the
high biocompatibility of the material and the possibility of adjusting
its composition to match particular tissue could pave the way for future applications in reconstructive medicine, prosthetics, pharmaceutics,
or soft robotics."

==========================================================================
In the past, scientists have already taken natural proteins as a basis
for developing artificial muscle systems and built them into miniscule molecular machines or into polymers. However, it has not yet been possible
to develop synthetic muscle materials that are entirely bio-based and
move autonomously with the help of chemical energy.

Material based on the natural protein elastin The material used by the
Freiburg team is based on elastin, a natural fibrous protein that also
occurs in humans, for instance giving elasticity to the skin and blood
vessels. Following the model of this protein, the researchers developed
two elastin-like proteins, one of which responds, for example, to
fluctuations in pH, the other to changes in temperature. The scientists combined the two proteins by means of photochemical cross-linking to
form a bilayered material. It is possible in this process to flexibly
shape the material and set the direction of its movement.

Contractions can be switched on and off with the help of temperature
changes The researchers succeeded in inducing the rhythmic contractions
by using a chemical energy source as fuel, in this case sodium sulfite. In
an oscillating chemical reaction in which the pH changes in cycles due to
a special linkage of several reactions, the added energy was converted
into mechanical energy via non-equilibrium states of the material. In
this way, the researchers induced the material to contract autonomously
in a cyclical manner. They were also able to switch the contractions on
and off with the help of temperature changes: The oscillating chemical
reaction started at a temperature of around 20 degrees Celsius, and the material began to make rhythmic movements. In the process, it was possible
to program certain states for the material to assume and to reset them
again with another stimulus. The scientists thus achieved a simple system
for implementing learning and forgetting at the material level.

"Since it is derived from the naturally occurring protein
elastin and is produced by us through biotechnological means,
our material is marked by a high sustainability that is also
relevant for technical applications," explains Schiller. "In the
future, the material could be developed further to respond to other
stimuli, such as the salt concentration in the environment, and to
consume other energy sources, such as malate derived from biomass." ========================================================================== Story Source: Materials provided by University_of_Freiburg. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Matthias C. Huber, Uwe Jonas, Stefan M. Schiller. An Autonomous
Chemically Fueled Artificial Protein Muscle. Advanced Intelligent
Systems, 2022; 2100189 DOI: 10.1002/aisy.202100189 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220128141254.htm

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