An image showing the receptor as a blue, elongated structure sitting in the middle of a cell membrane, shown as a vertical cross section shown

For the first time, an artificial molecular motor has been created that can “talk” to living cells – by gently pulling on their surface with enough physical force to induce a biochemical reaction. The approach could help scientists decipher the language that cells in tissues use to communicate with one another.

“There is a mechanical language in the form of physical forces that are exerted by the cells themselves, and we want to understand what information is transmitted and what consequences this has,” explains Aránzazu del Campo, who carried out the study at the Leibniz Institute for New Technology Materials headed, Germany. “Ultimately, we want to be able to give cells signals and control their function if they cannot do this themselves in the event of illness.”

To study how cells communicate by sensing mechanical stimuli and generating biochemical reactions, they usually have to be nudged with pipettes or the tip of an atomic force microscope. However, this does not work at the more complex tissue level.

Now, del Campo’s team has shown how this could be achieved with alkene-based molecular motors that use energy from ultraviolet (UV) light to gently pull cell membranes with tiny force and trigger a biochemical reaction.

The motors consist of a stator and a rotor part from which four polyethylene glycol arms protrude. Motors are attached to membrane receptors of cells in culture with two of these arms. Meanwhile, the other two arms are tied to a hydrogel that mimics a cell surface or a protein that a cell would normally interact with.

T-cell activation scheme

The motors rotate under UV light pulses, causing the two pairs of arms to roll up and shorten. They then pull on the cell membrane and trigger natural cell reactions, for example by enlarging their focal adhesions – macromolecular assemblies that create mechanical connections for the transmission of signals between cells. In another experiment, the researchers were able to use the motors to activate T cells, which are essential for the immune system. “We could save functions that cells have lost or trigger processes that cells can no longer go through,” says del Campo.

“This strategy of integrating motors into living systems has a lot of potential,” comments Nathalie Katsonis from the University of Groningen in the Netherlands. “It’s an elegant approach that has some similarities with biological strategies – in the sense that it involves a mechanical step that connects the light stimulus with the complex function.”

Del Campo hopes the approach will lead to a better understanding of cell function, not just in cell cultures but in living systems and whole tissues. “Our next goal is to couple the motor with a force sensor to quantify the force ranges in which cells communicate with each other,” she says.

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