A newly designed artificial cell membrane, created by chemists and biologists at the University of California-San Diego and described in this week’s edition of the Proceedings of the National Academy of Sciences is reportedly capable of growing like actual living cells.
The findings, the authors explain, will make it possible for scientists to more accurately replicate the behavior of living cell membranes, which previously could only be modeled using synthetic cell membranes that could not have new phospholipids added to them. The newly created type of membranes, while also synthetic, can mimic many features of living cells.
“The inspiration for this research came from an interest in understanding the transition between chemistry and biology,” lead investigator Neal Devaraj, an assistant professor of chemistry and biochemistry at UC San Diego, told redOrbit via email. “Life emerged at some point from non-living materials, and this was an incredible event that we still have very little understanding of.”
“Our approach has been to create completely synthetic systems that, though highly simplified, can mimic some of the properties of more complex living structures,” he added. “In this work, we mimic membrane growth and reproduction by utilizing a simple autocatalyst (a catalyst that can create itself). This catalyst self-reproduction saves the system as membrane grows, as it ensures that the catalyst does not dilute out. In this manner, we can create artificial membranes that can grow nearly indefinitely, as long as simple reactive precursors are provided.”
Replacing a complex network of pathways with a lone autocatalyst
Devaraj explained that other researchers had previously exploited the ability of lipids to self-assemble into bilayer vesicles with properties similar to those of cellular membranes, but that no one had previously managed to mimic their ability to support persistent phospholipid membrane formation. His team focused on mimicking the synthesis and growth of cell membranes.
“Earlier, we showed that one could use artificial reactions to create cell membranes. These reactions required a simple catalyst to enable membrane formation,” he told redOrbit. “This was interesting, however, as we created more and more membranes, the catalyst diluted out, and membrane production ceased. Living cells have highly sophisticated and intricate pathways to enable membrane reproduction, which entails creating new membranes and new catalysts.”
In their new paper, Devaraj and his colleagues explained that they used the autocatalyst as a substitute for the complex and natural network of biochemical pathways typically found in cellular membranes. By using this autocatalyst to drive membrane growth, they were able to create a system that constantly transforms simple, high-energy building blocks into new artificial cell membranes – a discovery that could prove to be an important new research tool.
“The benefit of mimicking living systems from a practical point,” he told redOrbit, “is that there are some remarkable properties of life that we would be extremely interested in incorporating into man-made materials. For instance, the idea that we could create novel materials that could self-repair, reproduce themselves, or adapt to new environments is highly appealing. This work can represent a small step in that direction.”
“One of the most interesting findings in this work is that we saw that our growing membranes were able to selectively incorporate different molecules from the environment, which altered the composition of the resulting membranes,” Devaraj added. “Furthermore, the incorporation changes in response to environmental stress, which means the membranes can spontaneously change their composition in response to an environmental stress. I think this is a fascinating behavior for such a simple system. It crudely resembles the ability of much more complex cells to alter membrane composition in response to the environment.”