A team of researchers led by Ayusman Sen of Pennsylvania State University has developed a nanobot that can not only neutralize nerve agents, but also pump out an antidote at the same time. Based on a self-propelled enzyme molecule, the new technology also has wider promise as a drug delivery system.
Nerve agents or nerve gases are the most potent and most feared biochemical weapons that hung over the world's collective head during the Second World War and the Cold War. With the capability of killing millions with doses as small as 0.023 mg/kg, nerve agents are organophosphorus compounds that are a nightmare to deal with – as recent events in Britain have demonstrated.
Now, Sen and his team have come up with a nanotechnology that could be a promising new way of both neutralizing such agents and treating their victims. The new nanobots are the result of basic research into enzymes, which are a form of protein molecule that acts like a specialized catalyst. Put simply, a catalyst is a compound that enhances a chemical reaction, but isn't altered or used up by that reaction, so it can keep operating indefinitely.
An enzyme does the same thing, except it only works on a very specific chemical reaction rather than general reactions like a catalyst. These enzymes are one of the most basic of molecules without which even the simplest of cells would be incapable of functioning and we wouldn't be able to digest our food. For this reason, they have been the subject of intense study ever since their discovery.
But what surprised Sen's group was finding enzymes that don't just do their chemical thing, they also move while they do so. In other words, they are nanoscale machines. Exactly how they do this isn't yet known, though Sen speculates it could be that the molecules change shape during the reactions. Regardless, what is important was how they can be exploited.
"If we take enzymes and anchor them to a surface so they cannot move, and we give them their reactant, they end up pumping the fluid surrounding them," says Sen. "So they act as miniature fluid pumps that can be used for a variety of applications."
They are also very efficient pumps capable of moving several microliters of liquid per second. To make use of this, Sen's team embedded the enzymes in a gel that contained a nerve agent antidote. The enzymes themselves are able to break down the agents, rendering them harmless.
In action, the enzyme, called organophosphorus acid anhydrolase, interacts with the nerve agents and destroys them. As its does so, it pumps the solution, bringing in more of the agents to be neutralized. Simultaneously, the antidote is dissolved in the solution and the enzyme pumps it out to treat the victim. None of this requires any sort of power source.
When perfected, Sen sees such nanobot pumps being incorporated into NBC (nuclear, biological, chemical) suits for soldiers, rescue workers, or the police who may have to respond to nerve agent incidents. In addition, the technology could be used as a drug delivery system to treat conditions like diabetes.
The research was presented at the 256th National Meeting & Exposition of the American Chemical Society.
Source: American Chemical Society
