ITHACA, NY – If the typical male’s sexual imperative is any indication, the future of medicine literally may be at hand.A proof-of-principle study presented in early December to the American Society for Cell Biology by Cornell University’s Baker Institute for Animal Health proposes to harness the energy of flagella — the tiny, whip-like tails of sperm — to send nanobots and other microscopic medical devices whizzing around the human body to cure disease, regulate organs, monitor enzymes, and perform other medical functions.
Why sperm? According to Alexander Travis, one of the scientists involved in the study, “at that scale, biology provides the best functional motors.”
Using a biochemical called adenosine triphosphate (ATP), flagella propel sperm at a rate of about 7 inches per hour, much faster than the fastest human on record can swim. ATP is a high-energy compound found in high concentrations in mitochondria, the power plants of biological cells. It is one byproduct of glycolysis, or the normal metabolism of sugar. As ATP releases its stored energy, it decays into a simpler chemical form, leaving none of the counterproductive residue that might be left by manmade power sources.
In addition, in sperm, the 10 proteins involved in glycolysis have been engineered by nature so they don’t scatter as metabolism occurs. Instead, they “stick” to a scaffold-like structure within the sperm’s tail, where they hand off their energy to the next protein in a sort of assembly line as they decay. The process provides constant, focused energy instead of random (pardon the pun) “spurts.”
In research conducted by Travis and Chinatsu Mukai, scientists synthesized proteins from mouse sperm (which is closely related to human sperm) and stuck them to the surface of a gold chip covered with nickel ions. The results indicated the process could be used to power small devices in much the same organized, efficient fashion as sperm are powered.
“We believe it is one of the first, if not the first, example of building a biological pathway on a manmade surface,” Travis told MSNBC.
Travis sees many potential uses for the process, which he and Mukai have patented. For example, tiny capsules filled with cancer-fighting drugs could be sent to attack specific tumor cells, continuing to dispense their medication at a pre-determined rate. That would represent a huge improvement over current cancer-treatment methods that destroy healthy tissue in their quest to eradicate diseased cells.
The idea is not without caveats. Dr. Erkki Ruoslahti, a nanotechnology researcher and distinguished professor at the La Jolla, Calif.-based Burnham Institute for Medical Research, warned that sperm-inspired ATP generators likely would be recognized by human bodies as “foreign,” meaning any products derived from them would need to overcome strong immune responses. However, some nanoparticles already have surmounted that hurdle, as in the case of those used in advanced body imaging.
“These are not pie-in-the-sky technologies,” Ruoslahti told MSNBC. “They’re already with us.”
