For all the amazing things they do, most pharmaceutical drugs today are pretty dumb. We dump them into our bodies, they course through our blood stream, and then they do their thing. Occasionally, they work where they shouldn’t, causing side effects. There are exceptions, of course, and most drugs that most people take work just fine this way. But there are many cases—chemotherapy to treat cancer, for example—where the collateral damage from a crudely targeted drug can be significant.
Which is why researchers injected cockroaches with DNA folded like origami.
The world was first introduced to DNA origami on the cover of Nature in 2006 in the form of a classic yellow smiley face. Researchers had recreated the image by carefully placing “staples” along a double helix to draw certain parts of the strand together.
Now, researchers from Harvard and Bar-Ilan Universities have used this way of folding DNA to create little packages that only open when they encounter certain molecules. In the case of chemo drugs, that would mean a DNA nanobot would only drop its payload when it reaches a cancer cell, reducing the possibility for side effects.
The scientists tested the system in cockroaches. The DNA nanobots contained a compound that the insect’s immune system would react to, allowing researchers to see if the bots were unfolding the way they had hoped. They did.
Perhaps more promising is the level of control researchers have built into the system. Yogi Patel, writing for Ars Technica:
The scientists used these DNA-based discrete elements to construct a collision-based computer, with the collisions being between a key and a robot. Various logic gates—AND, OR, XOR, NAND, NOT, CNOT, and a half adder—could be put together using different combinations of robots.
The DNA gates all take two inputs in the form of other molecules. AND gates require that both inputs be present to open, while OR gates only require that one be present.
In other words, each nanobot has two receptors that check for the presence or absence of certain molecules. When both are present, they perform one function, AND; when only one is, they perform another, OR. Researchers can then combine these two basic gates to perform other, more complex functions that make silicon computers tick.
The team was able to inject enough nanobots into each cockroach to produce enough of the collision that created the logic gates that they say their system has computing power equivalent to a Commodore 64, a 1980s-vintage computer, they told Sarah Spickernell at New Scientist.
As a drug delivery system, DNA nanobots still have some hurdles to clear. Currently, they’re still too vulnerable to the human immune system to last inside our bodies long enough to deliver their pharmaceutical payloads. But scientists think it won’t be long before they’ve solved that problem, which could pave the way for clinical trials.