Scientists make world’s first supramolecular motor that runs on chemical fuel

Researchers at the Technical University of Munich (TUM) have developed a supramolecular-scale artificial motor powered by a chemical fuel to deliver rotational motion. This is the first time this has been achieved outside the realm of biology, a press release said.

The natural world has always inspired innovators and scientists. From the megastructures of airplanes to the tiny light sensors in our phones, objects in nature have inspired most of the things humans have built.

The mechanical motor, too, finds its origins in attempts at replicating motion that is abundantly seen in nature. While humanity has succeeded in achieving motion in a variety of ways on a large and small scale, achieving the same at a micro level has been difficult.

Until now.

How big is the microscopic motor?

Scientists have previously observed molecular-scale motors in primitive bacteria, such as archaea , which have fin-like structures called flagella. The organism uses this structure to move around and is powered by the fuel of cells, Adenosine Triphosphate (ATP).

Artificial replication of this structure was impossible until the research team led by Job Boekhoven, a professor of Supramolecular Chemistry, began working on it. The motor made by the team consists of peptide ribbons developed by the team that get activated when a chemical fuel (not ATP) is added.

Peptides are strings of amino acids, the building blocks of protein inside biological cells. When the chemical fuel is added, the ribbons curl into small tubes and then rotate. The entire setup is no longer than a few micrometers and only nanometers in width. However, it can be visualized live under a microscope.

What movements can the motor make?

Like other motors, the speed of the microscopic motor can be controlled by adjusting the amount of fuel added. On the other hand, the direction of the rotary movement, whether clockwise or anti-clockwise, depends on the structure of the molecular blocks in the ribbons.

If the supramolecular motor is to be used practically, researchers need to know the force it can generate. So, the researchers teamed up with Matthias Rief, a professor of Molecular Biophysics at TUM and an expert in using optical measurement methods. Together, the team found that the activated ribbons exerted enough force to move objects a few micrometers in size.

Building from here, the researchers hypothesize that if several such ribbons are brought together, one could create microscopic devices or “microwalkers” that could crawl on surfaces.

In the future, such micro walkers could carry medications to a particular body organ. Alternatively, they could swim through blood vessels on missions such as detecting tumorous cells.

However, such tasks cannot be developed soon since the fuel used by the researchers is not suitable for use inside an organism; rather, it is toxic. This needs to be resolved before the technology can be used for medical applications.

The research findings were published in the journal Chem .