Scientists Engineer "Minimal" Artificial Cell Capable of Chemical Navigation

Researchers at the Institute for Bioengineering of Catalonia (IBEC) have created the world's simplest artificial cell capable of "chemical navigation." This groundbreaking work, published in Science Advances, demonstrates how microscopic bubbles can be chemically engineered to autonomously migrate towards specific chemical substances, much like living cells do.

Unlocking the Secrets of Chemotaxis with a “Minimal Cell”

The core of this discovery lies in recreating chemotaxis, a vital biological process that allows living organisms to move in response to chemical signals. From bacteria seeking food to white blood cells migrating to infection sites, chemotaxis is a fundamental survival strategy.

"What we find particularly fascinating is that this type of directed movement can occur even without the complex machinery typically involved, such as flagella or intricate signaling pathways. By recreating it in a minimal synthetic system, we aim to uncover the core principles that make such movement possible" explains Bárbara Borges Fernandes, a PhD student at IBEC and the study’s first author.

The "Boat and Engine" of an Artificial Cell

To achieve this chemical navigation, the researchers designed a "minimal cell" using lipid-based vesicles, commonly known as liposomes. These are essentially tiny, spherical bubbles made of a fatty membrane, similar to a cell's outer layer.

Here's how this "minimal cell" functions:

• Encapsulated Enzymes: The researchers enclosed specific enzymes (either glucose oxidase or urease) inside these liposomes. These enzymes are biological catalysts that react with particular "substrate" chemicals in the environment, like glucose or urea, converting them into new products.
• Membrane Pores: Crucially, the liposomes' membranes were modified to include essential membrane pore proteins. These proteins act as tiny channels or gateways, allowing the external substrate chemicals to enter the synthetic cell and the products of the internal enzyme reactions to exit.
• Generating Movement through Chemical Gradients: The continuous process of chemicals entering, reacting inside, and then exiting the vesicle creates a difference in chemical concentration around the particle. This asymmetry in chemical concentration then generates a fluid flow along the vesicle’s surface. This flow acts as a self-propelling force, directing the particle's movement. Professor Battaglia likens it to the liposome being a boat, with the pore and the enzyme serving as its engine and navigation system.

From Passive Drift to Directed Movement

The research team conducted extensive experiments, tracking the movement of over 10,000 vesicles within microfluidic channels containing precise gradients of glucose or urea. They compared vesicles with varying numbers of pores to control vesicles that lacked pores entirely. Vesicles without pores drifted randomly, exhibiting only passive motion. As the number of pores increased, a chemotactic effect emerged, eventually reversing the direction of movement and actively guiding the vesicles toward regions with higher concentrations of the substrate.

Borges explains the key finding: "We observe that the control vesicles move towards lower substrate concentrations due to passive effects other than chemotaxis. As the number of pores in the vesicles increases, so does the chemotactic component. Eventually, this reverses the direction of movement, causing the vesicles to move towards areas with higher substrate concentrations." This critical reversal in direction confirms that the engineered vesicles are actively navigating towards a specific chemical “trail.”

A Blueprint for Future Innovations

The ability to engineer such a simple, yet purposeful, artificial cell opens up new avenues for understanding life itself. "Watch a vesicle move. Really watch it. That tiny bubble holds secrets: how cells whisper to each other, how they ship life’s cargo. But biology’s machinery is noisy, too many parts! So, we cheat," remarks Battaglia. "We rebuild the whole dance with just three things: a fatty shell, one enzyme, and a pore. No fuss. Now the hidden rules jump out. That’s the power of synthetic biology: strip a puzzle down to its bones, and suddenly you see the music in the mess. What once seemed tangled? Pure, elegant chemistry, doing more with less."

Beyond fundamental biological insights, this breakthrough provides a crucial blueprint for engineering targeted drug delivery systems. Imagine tiny "smart capsules" that can autonomously navigate through the bloodstream, following chemical signals released by diseased tissues (like cancer tumors or inflammatory sites). These capsules could then deliver medication directly to the affected area, minimizing damage to healthy cells and significantly reducing side effects. While still in the research phase, this technology holds immense potential to revolutionize how we approach medical treatments.

The study was a collaborative effort, involving contributions from José Miguel Rubí’s team at the University of Barcelona, the Institute for Physics of Living Systems and the Department of Chemistry at University College London, the University of Liverpool, the Biofisika Institute, and the Ikerbasque Foundation for Science.