Over the past few decades, researchers have built microscopic molecular machines that can spin or shuttle other molecules. However, it is difficult to determine the mechanical and force action that generates these tiny parts, which is important when using them as nanorobots or in artificial muscle.
Now, in Journal of the American Chemical SocietyThe researchers report that the torsion and non-twist molecular motors are like spinning toys – allowing the energy and torque of their rotations to be measured.
Twisting this molecule can twist in the opposite direction and the researchers can measure its force. Image credit: Adapted from the Journal of the American Chemical Society 2022, DOI: 10.1021/jacs.2c02547
Nature has engineered many different kinds of molecular machinery, whether in the hair-like flagella that propel bacteria or in the cyclic enzyme that produces the energy-storing compound adenosine triphosphate (ATP). Researchers have been creating versions of them for use as transport vehicles or pumps, or to make materials that can store and release mechanical energy.
Although many designs are now available, it is still difficult to design them for repetitive rotations and measure how much force – or force over a distance – they can exert. . So Nicolas Giuseppone and colleagues set out to build molecular machines with reversible periodic motion that would allow them to do just that.
The researchers built a figure eight molecular machine with a rotating motor at its center and a polymer chain in each of its two rings. The rotation is UV-activated at the intersection of figure-8 and causes the rings to twist around each other once, twice, or three times.
With the lights off, machines with progressively smaller loops untethered to relieve stress, much like unrolling a revolving toy. The researchers then conducted non-torque experiments at different temperatures to calculate work, force, and torque. Whirligig produces the same torque as the well-known enzyme that produces ATP, thus providing a promising glimpse into the mechanical energy that can be stored and released by these microscopic machines.
Source: acs.org
