Sperm Power: New Tool for Nanobots

Sperm Power: New Tool for Nanobots

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Scientists have taken the first steps in reproducing the biological engine that powers a sperm's tail and modified it for use in nano-sized devices. But will it work? No one can say for sure.

Scientists have taken the first steps in reproducing the biological engine that powers a

sperm's tail and modified it for use in nano-sized devices.

The tiny biological machine is something like a car engine that uses fuel to generate motion.

Only this machine -- composed of 10 carefully arranged enzymes -- runs on natural sugars, using them to produce an high-energy molecule called adenosine triphosphate, or ATP for short.

In the case of sperm, ATP energizes the tail. But it could also be used in nanorobots that do everything from activate drug-delivery pumps to manufacture missing enzymes necessary for healthy bodily functions.

"We're taking what sperm have already figured out how to do and using it for a nanotechnology application," said Alex Travis, assistant professor of reproductive biology at Cornell University College of Veterinary Medicine in Ithaca, NY.

The enzyme engine was particularly interesting to Travis and his team because, unlike most enzymes that like to stick to squishy cellular matter, these like to stick to the rigid, fibrous structure inside a sperm tail. This can be important for artificial applications.

Enzymes bend, twist and rotate as part of their normal functions. Many enzymes, put inside a manufactured nanobot, would not attach to the device properly. But the sperm tail enzymes naturally work on rigid surfaces; the trick is getting them to stick to manmade devices.

To do that, the researchers changed a part of the enzyme that lets it attach to the fibrous tail structure so that it would attach to nickel ions on a manufactured chip.

So far, they have attached three of the 10 enzymes -- two that are next to each other and one from the middle of the sequence. When attached, the enzymes activate and perform their normal function. If the scientists can get all 10 enzymes to work in sequence, they'll have their biological engine. Blood glucose naturally present in the body would be used as fuel.

On a working device, the enzymes would use the glucose to make ATP, which in turn would power mechanical functions or initiate chemical reactions for therapeutic reasons.

"I think what's really interesting is that it appears to work," said Regina Turner, assistant professor of large animal production at the University of Pennsylvania School of Veterinary Medicine.

But all of the enzymes will need to work together to make the biological engine.

"He will need to show that he can do this with the entire pathway," said Turner.

And if that happens, it will be important to find a way to get the energy from the biological engine to the necessary parts of the nanodevice.

Because the researchers are focused exclusively on building the engine, said Travis, bioengineers will eventually need to solve the energy-delivery problem.