By Janet Fang            March 18, 2015 

photo credit: Cell-targeting DNA nano-robots bearing antibody-fragment payloads, from S.M. Douglas et al. 2012 Science / Campbell Strong, Shawn Douglas, & Gaël McGill

This year, researchers hope that tiny robots built entirely of DNA will help save a critically ill leukemia patient. These DNA nanobots are designed to seek out and destroy cancer cells, while leaving healthy cells unscathed. So far, they’ve only been tested in cell cultures and animal studies. 
Ido Bachelet of Israel’s Bar-Ilan University (and formerly of Harvard’s Wyss Institute) announced their human trial last year at the British Friends of Bar-Ilan University event. “No, no it’s not science fiction,” he said. "It’s already happening."
The technology is modeled after our body’s own defenses. Like white blood cells, the nanobots patrol the bloodstream, looking for signs of distress. DNA is a naturally biocompatible and biodegradable material, and the devices are designed to not incite an immune response.
In a 2012 Science paper, Bachelet and colleagues described a DNA nanobot shaped like a hexagonal tube, with its two halves connected by a latched hinge (pictured above). When the little device recognizes a target cell based on its surface proteins, the two halves swing open like a clam to deliver a tiny but deadly cargo of drugs or nanoparticles. These could be molecules that force cancer cells to self-destruct by interfering with their growth, for example. When the researchers released their tiny bots into a mixture of healthy and cancerous human blood cells, half of the cancer cells were destroyed within three days. No healthy cells were harmed. 
Then about a year ago, a newer version of these DNA nanobots were injected into live cockroaches. These devices were created using DNA strands that would self-assemble into a box with a controllable lid. Each box contained a molecule that binds hemolymph cells (like blood cells in people), and the nanobots themselves were labeled with fluorescent markers so Bachelet's could follow them. These findings, published in Nature Nanotechnology, demonstrated the accuracy of their tiny delivery system. 
Is this nano-sized technology now ready for humans? In his announcement last year, Bachelet said the DNA nanobots can currently identify 12 different types of cells in humans, ranging from solid tumors to the abnormal white blood cells associated with leukemia. 
The patient selected for this year’s early trial has been given only a few more months to live. The team expects to remove the cancer within one month.