Semi-synthetic cells could revolutionise everything from sensors to healthcare

The more we study natural biological cells, the more we learn about how to control them or build artificial, synthetic versions. These independent avenues of study have huge potential, but also their limitations. Now researchers from Imperial College London, who recently also made a significant breakthrough in treating Multiple Sclerosis, have worked out a way to borrow the strengths of each, fusing together living and non-living synthetic cells to create tiny chemical factories that might one day aid drug delivery, create new strange semi-synthetic organisms, and even help us realise new forms of cellular based manufacturing.

In past work, scientists have packaged proteins and enzymes inside artificial casings to better treat conditions like Cancer or Diabetes. Rather than just using some natural parts, the Imperial College study instead wrapped entire biological cells inside artificial ones.

"Biological cells can perform extremely complex functions, but can be difficult to control when trying to harness one aspect," says Oscar Ces, lead researcher on the project, "artificial cells can be programmed more easily but we cannot yet build in much complexity. Our new system bridges the gap between these two approaches by fusing whole biological cells with artificial ones, so that the machinery of both works in concert to produce what we need."

To pair up natural and artificial cells, the team used a micro-fluidic process to guide liquids very precisely through tiny channels. A liquid solution containing the biological cells was carefully pumped into a tube of oil, which forces the liquid into droplets surrounded by a lipid shell. Then, the droplets containing cells were dripped into a chamber where oil was floating on top of water. Their weight dragged them down into the watery solution, sealing them inside a bi-layered bubble that could then be encased in the artificial cell wall.

The end result are hybrid cells, made up of an artificial shell containing a natural cell and enzymes. To test whether the living and non-living halves of the cell worked together, the team designed an experiment where the two parts would come together to produce a fluorescent chemical. Sure enough, a healthy glow indicated that all was in working order.

The team also tested the durability of the cells by placing them in a copper-rich solution. This mix would normally kill biological cells, but the team found that the hybrid cells were still fluorescing, indicating that the tough outer shell was protecting the natural innards. This function could prove handy in vivo, where a patient's immune system might attack foreign cells used in a treatment.

The researchers say the technique could have a range of applications for targeted drug delivery, sensors or even creating cellular "batteries" that run on the process of photosynthesis. With further study, the artificial casing could be made to function more like the real thing, opening its shell on demand to release its payload.

"The system we designed is controllable and customizable," says Yuval Elani, first author of the study, "you can create different sizes of artificial cells in a reproducible manner, and there is the potential to add in all kinds of cell machinery, such as chloroplasts for performing photosynthesis or engineered microbes that act as sensors."

The research was published in the journal Scientific Reports.