Cell-like structures, known as “cell mimics” have been produced with the capacity to perform many activities previously limited to living cells. Although they can't replicate, they could be used as delivery vehicles – taking drugs to where they need to go in the body – and to clean up pollution.
The cells in our body share with single-celled organisms the capacity to draw molecules inside or pump them out. Without this, they would be useless, dying swiftly from a lack of energy and nutrients. On the other hand, if too exposed to the surrounding environment, they would be at the mercy of everything around them.
Long-term studies on artificial cells have succeeded in replicating some features of living cells, but have lacked the capacity to capture molecules when working against a concentration gradient. In Nature, New York University's Dr Stefano Sacanna and co-authors report this is no longer true, having created cell mimics that can achieve this key trait when activated by light or changes in acidity.
"At the heart of the cell-like structure's design is the synergy between an active element that powers it from the inside and the physical constraints imposed by the cell walls, allowing them to ingest, process, and expel foreign bodies," Sacanna said in a statement.
The capacity to move molecules from a low concentration site to a higher one is called active transport. Without it, cells can neither take in what they need to flourish from outside nor expel waste that would otherwise harm them. This is what Sacanna's team have brought to their mimic cells.
The authors report they placed artificial cells in water and turned them on using light. The cells took up particles from their environment, offering a path to cleaning up ecosystems. "Think of the cell mimics like the PAC-MAN video game—they go around eating the pollutants and removing them from the environment," Sacanna said.
The team demonstrated their creations can not only consume pollutants humans put into the water supply, but living cells such as E. coli. The process also works in reverse, with the mimic cells carrying a payload they can release when given the appropriate signal. This could make them the perfect carriers within the bloodstream, for example transporting chemotherapy directly to tumors so other organs are not affected.
The team report they “borrow[ed] no materials from biology.” It might sound like their work requires complex machines, but instead, they added molecules to oil droplets to form spherical hollow colloids that, in the right conditions, inflate around water droplets.