Scientists have developed a new family of molecular machines that can convert the energy of ordinary sunlight into unidirectional rotational motion with exceptional efficiency.

The synthetic motors, consisting of only a dozen or so atoms, have already surpassed solutions created by nature in terms of efficiency.

In every cell of the human body, vast numbers of tiny molecular machines are at work.

'These are proteins that perform specific, directional movement and convert it into mechanical or chemical work. We live thanks to them', Wojciech Danowski, PhD, from the University of Warsaw explains in an interview with PAP.

The scientist mentions kinesins, which move along special routes to remove cellular waste, and proteins in muscles that perform a series of small steps, the sum of which can be seen in movements such as those of an arm or leg.

Most of these motors are set in motion by another mechanism: ATP synthase, which, as it rotates, charges chemical cellular batteries that power other machines.

However, there are motors in nature that only require light to operate. One such system is retinal, a molecule present in rhodopsin, a protein found in the rods of the retina, thanks to which vision is possible.

Evolution found a way to harness the Sun's energy and transform it into the work of tiny molecular machines.

'This is extremely inspiring, which is why we, chemists, make our own synthetic molecular machines. The difference is that ours are much, much smaller: only a dozen or so carbon atoms, while in the case of biological ATP synthase we are talking about several thousand such atoms. However, these machines work in an similar way - one part of the molecule performs a unidirectional spinning motion relative to the other' Danowski explains.

Now, the team in which he worked - led by Nobel Prize winner Ben Feringa - has managed to develop molecular motors powered by ordinary daylight.

This is a breakthrough because until now, powering similar structures required UV light, laser light or light from diodes, which is harmful to living cells. Now, free daylight is enough to power the motor.

The new family of machines developed by the scientists demonstrates exceptional efficiency in the use of the light that drives them - that is, it extremely efficiently converts the supplied photochemical energy into mechanical energy associated with rotation.

Danowski explains that the spinning movement of nanomotors immersed in the solution is not visible to the naked eye because each of them is tiny and rotates in a different direction.

Scientists now face the task of ensuring that these tiny machines work together and that the effects of their work are visible on a macroscopic scale.

'It is within our capabilities', Danowski says.

The researcher also aims to increase the efficiency of the motors so that no photon that has a chance to excite them is wasted.

The record efficiency of chemical reactions that scientists have achieved so far in the systems they have tested is 80 percent. However, Danowski believes that the reaction efficiency of about 100% is within reach.