The tiny payloads of cargo they deliver gets individual, living cells to change their behavior – such as causing cancer cells to self-destruct – improving current drug-delivery systems.
The researchers exploited a technique called DNA origami, which folds DNA strands together into complex shapes. Here, they constructed a hexagon-shaped nano-sized robot. (It’s called a robot because it’s capable of some robotic tasks.)
Once the device recognizes a cell, it automatically changes its shape and delivers its cargo of nanoparticles or antibodies. According to a Harvard release, it takes the form of an open barrel whose two halves are connected by a hinge (pictured):
The DNA barrel, which acts as a container, is held shut by special DNA latches that can recognize and seek out combinations of cell-surface proteins, including disease markers. When the latches find their targets, they reconfigure, causing the two halves of the barrel to swing open and expose its contents.
“You can think about it as a sort of combination lock,” says coauthor Ido Bachelet of Harvard. “Only when both markers are in place, can the entire robot open.” (It also helps to image a clam shell opening.)
- To test its therapeutic potential, the team created a nanorobot with locks that unzipped in response to molecules expressed on the surface of leukemia cells.
- They loaded it with a single molecule known to kill cells by interfering with their growth cycle.
- They released millions of copies into a mixture of healthy and cancerous human blood cells.
- Three days later, around half of the leukemia cells had been destroyed, but no healthy cells had been harmed, New Scientist explains.
This technique was modeled on the body's own immune system, where white blood cells patrol the bloodstream for any signs of trouble. And since DNA is a natural biocompatible and biodegradable material, DNA nanotechnology is widely recognized for its potential as a delivery mechanism for drugs and other molecules.
“In diseases such as cancer we know if we can find every single last cell and kill or reprogram it, we can cure that disease,” says coauthor Shawn Douglas of Harvard. They’re now thinking about testing the nanobots in mice.
The study was published in Science today.
Image: Campbell Strong, Shawn Douglas, & Gaël McGill