Nano-chopper to deliver medication

Nanobiotechnologists at Cornell University have built and tested the first biomolecular motors with tiny metal propellers.

Fuelled by adenosine triphosphate and spinning nickel propellers at eight revolutions per second, molecular motors made of ATPase enzyme are believed to herald a new generation of minuscule, robotic, medical devices.

Such nanomotors might ultimately power small mixers to mix up tiny batches of drugs, then pump out the freshly prepared pharmaceuticals directly to tissues that need them.

‘With this demonstration, we believe we are defining a whole new technology,’ said Carlo D. Montemagno, associate professor of biological engineering and leader of the molecular-motor mechanics. ‘We have shown that hybrid nanodevices can be assembled, maintained and repaired using the physiology of life.’

The little metal propellers – which measure around about 750 nm in length and 150 nm in diameter – were made at the Cornell Nanofabrication Facility using techniques including electron gun evaporation, e-beam lithography and isotropic etching.

Thin coatings of attachment chemicals encouraged the propellers essentially to self-assemble with molecules of ATPase. ATPase converts the cellular fuel ATP (adenosine triphosphate) into ADP (adenosine diphosphate); the chemical energy released by this reaction is what powers the machine.

Mounted on 200-nm-high pedestals and immersed in a solution of ATP and other chemicals, some of the biomolecular motors spun their propellers for two-and-a-half hours.

Eventually, the Cornell nanobiotechnologists aim to engineer biomolecular motors that run on light energy, with photons instead of ATP. They also plan to add computational and sensing capabilities to the nanodevices, which ideally should be able to self-assemble inside human cells.

This is only a first step as the technology is still very inefficient. Only five of the first 400 biomotors worked. ‘We need to achieve a higher level of site occupancy,’ said Montemagno. And scientists will have to show that the machines can function inside the living cell, something that may take many years to achieve.