One of nature’s best strategies for locomotion at the cellular scale involves powerful molecular motors: complex molecules that convert chemical energy into mechanical energy for tasks such as transporting components within cells, contracting muscle fibers and snipping strands of DNA.
Since 1999, chemists have been designing synthetic molecules that can rotate 360 degrees in response to light or chemical stimuli. These single-function motors can generate force on surfaces, transport cargo to sensors and power nanoscale devices. But when they’re placed in opaque biological tissue, researchers can’t easily control or track them.
According to published in scientific progress“There aren’t many compounds that exhibit two different responses to light, and this is the first motor to exhibit this property,” says Maxim Pshenichnikov, a spectroscopist at the University of Groningen in the Netherlands and co-author of the new study.
Pshenichnikov and his colleagues in Groningen organic chemist and 2016 Nobel Laureate Ben Feringa, created the bifunctional molecule by attaching a chemical called triphenylamine to a basic molecular motor. This lets the motors respond differently to different light energies. Low-energy light powers the motor just enough to spin, while high-energy light over-excites it, causing it to dispose of the excess energy by emitting photons: it fluoresces. Also, unlike typical molecular motors powered by tissue-damaging ultraviolet light, the new compound responds to infrared light, allowing it to penetrate deep into the skin without causing damage.
Motors like these can help in applications that require precise positioning. For example, fluorescent motors could interact with different cellular structures and glow to track as drugs are delivered and activated. “How cool would it be if we could actually track motor movement in cells and use it for mechanical perturbation, [drug] Delivery and testing? ’ said Feringa.
Salma Kassem, a chemist at the City University of New York who was not involved in the study, says the design is an important step toward light-driven pharmacology: “Combining self-reporting and function into one small molecule without two properties interfering with each other . This work achieves a separation of roles in a simple and elegant way.”
The researchers intend to apply the technique to motors with biological functions, such as binding to certain cell receptors. They will then test its performance in living cells or tissues. The success of the technique “gives me hope that we can easily transfer it to motors made with different compounds,” says lead author Lukas Pfeifer, an organic chemist at EPFL in Switzerland.
