Two researchers at the University of California, Santa Barbara, created a gel made of DNA that mechanically responds to stimuli in much the same manner as human cells.
At only 10 microns wide, the DNA gel is roughly the size of a human eukaryotic cell, and shows similar active fluctuations and mechanics to cells. The gel contains stiff DNA nanotubes linked together by longer, flexible DNA strands serving as the substrate for molecular motors.
Researchers can control the stiffness of the nanotubes and the manner and extent of their cross-linking, which determine how the gel responds to stimuli, by applying DNA design, said Deborah Fygenson, Ph.D., associate professor of physics, and also affiliated with UCSB’s Biomolecular Science and Engineering (BMSE) program.
Using a bacterial motor protein called FtsK50C, Dr. Fygenson and Omar Saleh, Ph.D., an associate professor of materials also affiliated with UCSB's BMSE program, caused the gel to react as cytoskeletons react to the motor protein myosin—by contracting and stiffening. The protein binds to predetermined surfaces on the long-linking filaments, and reels them in, shortening them and bringing the stiffer nanotubes closer together. To determine the gel's movement the scientists attached a tiny bead to its surface and measured its position before and after activation with FtsK50C.
Drs. Fygenson and Saleh published results of their research online in Proceedings of the National Academy of Sciences.
"This is a whole new kind of responsive gel, or what some might call a 'smart' material,” Dr. Saleh said in a statement.
Unlike other smart gels based on synthetic polymers, the DNA gel is powered by adenosine triphosphate (ATP). "The gel has active mechanical capabilities in that it generates forces independently, leading to changes in elasticity or shape, when fed ATP molecules for energy—much like a living cell,” Dr. Saleh said.
Drs. Saleh and Fygenson have begun working to refine the DNA gel by enabling distinct movements, such as twisting and crawling, or using other motor proteins that would allow the gel to mimic other cell behaviors, such as shapeshifting and dividing.
Craig Hawker, Ph.D., FRS, director of UCSB’s Materials Research Laboratory, said in a statement the DNA gel has potential applications in fields that include smart materials, artificial muscle, cytoskeletal mechanics, and nonequilibrium physics, as well as DNA nanotechnology.
[Read an abstract of the study here: http://www.pnas.org/content/early/2012/10/01/1208732109.abstract]