In many ways, Sperm is the perfect biological delivery system. It generates it’s own energy, can traverse rough terrain and knows how to hone in on its target to deliver the goods. While sperm delivers DNA, Cornell researchers are now borrowing ideas from sperm to provide energy for nanoscale robots aiming to deliver medication from nanosized medical devices.
In order to deliver medicine inside the human body, nanoscale medical devices need energy to carry out tasks, such as releasing drugs. Alex Travis, Cornell assistant professor of reproductive biology aims to recreate the sperm system to generate power for nanoscale robots, based upon how sperm makes energy to swim.
A midsection between the head and the long tail of sperm contains mitochondria, organelles that generate a cell's power. But sperm have also developed a second energy source to power their long tail. They employ a process known as glycolysis, which breaks down glucose to derive ATP, which cells use for energy.
The pathway for glycolysis requires 10 enzymes. Using special "targeting domains," sperm tether these to a fibrous sheath that runs the length of the tail. In this study, the researchers aim to re-create this glycolytic pathway by modifying each protein's targeting domain so that they can instead bind to nickel ions on a manufactured chip.
So far, they have successfully attached three of the 10 enzymes required to make ATP from glucose, and each has remained functional. If they manage to attach all 10 enzymes, each enzyme will in principle act in a series to ultimately generate ATP to power a nano-device. In the body, such a device could conceivably use readily available blood glucose as fuel.
Potential uses include delivery systems loaded with chemo drugs or antibiotics to target specific cells. Such a system would allow doctors to provide steady doses while reducing side effects that result from treating the entire body with a drug.
"As a proof of principle that this kind of strategy could work, we've shown that the first two enzymes could be attached to the same chip and act in series," said Chinatsu Mukai, a postdoctoral associate in Travis' lab.
Travis believes this pathway has the potential to overcome one of the major obstacles currently confounding the emerging nanomedical field.
“One of the major limitations in making implantable, nanomedical devices is providing power to them,” said Travis. “If you can engineer a device that can make its own energy, then it can potentially last longer and regulate its own task rate.”
Travis' group is trying to get funding to complete attaching the rest of the enzymes in the glycolysis pathway. "We have a provisional patent, so if a company shows interest, we could also work something out with them," said Travis.
He will present his research at the American Society for Cell Biology Annual Meeting, Dec. 3, and he will discuss this idea at a press briefing in Room 101 of the Washington Convention Center at 10 a.m.
Posted by Rebecca Sato
*This post is an adaptation of a Cornell University news release.
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