Researchers build artificial cells that sense and respond to their environment
Artificial cells could be used to detect changes in the body and react by releasing drug molecules, or to detect and eliminate harmful metals in the environment.
Reaction to chemical changes is a crucial function of biological cells. For example, cells can react to chemicals by creating certain proteins, stimulating energy production or self-destructing. Chemicals are also used by cells to communicate with each other and coordinate a response or send a signal, such as a pain pulse.
However, in natural cells, these chemical responses can be very complex and involve multiple steps. This makes them difficult to design, for example, if researchers wanted natural cells to produce something useful, such as a drug molecule.
Instead, Imperial researchers are creating artificial cells that mimic these chemical responses in a much simpler way, making it easier for them to be designed.
Now, the team has created the first artificial cells that can detect and respond to an external chemical signal by activating an artificial signalling pathway. They have created cells that detect calcium ions and react by fluorescence (glow). Their results are published today in the Proceedings of the National Academy of Sciences.
The first author, James Hindley of Imperial's Department of Chemistry, said, "These systems could be developed for use throughout biotechnology. For example, we could consider creating artificial cells capable of detecting cancer markers and synthesizing a drug in the body, or artificial cells capable of detecting dangerous heavy metals in the environment and releasing selective sponges to clean them."
The team created an artificial cell that contains smaller cells ("vesicles"). The edge of the cell is formed by a membrane that contains pores, which allows calcium ions to enter. Inside the cell, calcium ions activate enzymes that cause fluorescent particles to be released from the vesicles.
James added: "Biology has evolved to become robust using complex metabolic and regulatory networks. This can make editing cells difficult, as many existing chemical response pathways are extremely complicated to copy or design.
"Instead, we have created a truncated version of a path found in nature, using artificial cells and elements from different natural systems to create a shorter and more efficient path that gives the same results."
The researchers' system is simpler because it does not need to take into account everything that cells need to move through natural systems, such as by-products that are toxic to the cell.
In the system, the membrane pores and calcium-activated enzymes come from existing biological systems - the enzyme is derived from bee venom, for example - but they are not found in the same natural environment.
According to the researchers, it is the strength of using artificial cells to create chemical responses - they can more easily mix elements found in nature than adding an external element to an existing biological system.
