Nanobots fighting nerve agents: an enzyme driven fluid pump

Researchers from Penn State have been studying the movement of enzymes found in nature and found that they can harness the energy from catalyzing a reaction and use it to act as a nano-fluidic pump.

Aug 21, 2018

Nanobots always seem to be something that super-villains utilize as part of a plan to take over the world. Thankfully, in this case, quite the opposite is true. Scientists from The Pennsylvania State University (Penn State; PA, USA) have developed ‘nanobot pumps’ that can simultaneously break down nerve agents and administer an antidote.

The project came about when Principal Investigator Ayusman Sen, the lead researcher at a group from Penn State, and his team were studying the movement of enzymes in the body: "We have been looking at how to convert chemical energy into motion," he commented. "We take the energy that's generated from catalytic reactions to cause the motion of enzymes." The research was presented at the 256th National Meeting and Exposition of the American Chemical Society (19–23 August 2018; MA, USA).  

Enzymes are protein structures that work as catalysts to increase the energy of the components in a reaction so that they reach the activation level, enabling the reaction to take place much faster. Enzymes in nature were originally thought to move through cell systems by passive diffusion, catalyzing reactions as and when they happened across their respective reactants.

However, Sen, among others, have recently shown that this is not necessarily the case, with enzymes apparently utilizing the ‘waste’ energy of the reaction to move through the cell.

Furthermore, Sen’s group has shown that enzymes can in fact swim along a set path toward higher levels of reactant –where they are most needed.

To harness this excess energy and form a pump-like structure, Sen proposed to anchor the enzymes to a non-moveable surface, ensuring they can only catalyze the reactants around them, rather than moving off to find their reactants themselves.

"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," Sen explained. "So they act as miniature fluid pumps that can be used for a variety of applications.”

The ability of these nanobots to harness the chemical energy available in their environment and move autonomously by way of creating a continuous surface force in a fluid means that they can also be used as a nanofluidic pump, providing control over flow rate and turning on in response to specific stimuli. As the system uses the energy from the reaction it needs no external power source, making it a very important discovery for applications not only in medicine.

Sen and his team at Penn State have been utilizing this nano-enzyme-pump to neutralize a group of nerve agents called organophosphates. The enzyme used – organophosphorus acid anhydrolase – was immobilized on a gel that also contained an antidote to the nerve agent. Exposure to the nerve agent activates the enzyme, which pumps the nerve agent in, destroying it, and pumps out the antidote to heal the effects.

This could have applications in the military as exposure to these chemicals during combat or terrorist attacks can cause permanent neurological damage, and in some cases, death.

That is just using one example of the potential applications of these nanobots. If the nanobots were formed using different enzymes, the applications would be different. For example, to treat diabetes it would be possible to use an insulin pumping nanobot or the nanobot could be used for precise and sustainable drug delivery.

“If you want to make pumps that will pump very small amounts of liquid in a very precise way, this is one way to do that,” Sen concluded. 

This discovery marks the beginning of an exciting time in research into the use of nanobots with potential applications in medicine, manufacturing, robotics and fluidics.

Source: Sen A. Designing self-powered nanobots. ACS National Meeting and Exposition 2018 (19–23 August; MA, USA) 

Lucy Chard

Commissioning Editor, Future Medicine

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