It sounds like the stuff of science fiction, but Omar Saleh and Deborah Fygenson at the University of California Santa Barbara have developed a DNA-based "smart gel" that can contract and move in response to stimuli in a similar way to living cells. Writing in the journal PNAS, the scientists created a cell-sized blob of goo made of a mixture of short and long DNA strands, together with special proteins known as motor proteins, which can reel in or spool out the strands. By feeding the motor proteins ATP molecules, which act as an energy source, they move the DNA strands around, changing the shape and stiffness of the gel.
Because DNA molecules can be engineered to have different properties by changing the sequence of 'letters' in them, and because there is a huge range of motor proteins that could be used, this discovery potentially opens the door to bioengineered 'smart materials' that could be used to make artificial muscles or other useful things. The researchers are now refining their blob, to try and create something that can move in specific ways, such as twisting or crawling, which would bring more control.