Toronto: Scientists have designed a nanorobotics system that may be used to study the properties of cancer, and help improve diagnosis and treatment of the deadly disease. The nano-bot, described in the journal Science Robotics, is a set of magnetic 'tweezers' that can position a nano-scale bead inside a human cell in three dimensions with unprecedented precision.
"Optical tweezers -- using lasers to probe cells -- is a popular approach," said Xian Wang, a PhD candidate at the University of Toronto in Canada.
The technology was honoured with 2018 Nobel Prize in Physics, but Wang said the force that it can generate is not large enough for mechanical manipulation and measurement he wanted to do.
The system Wang designed uses six magnetic coils placed in different planes around a microscope coverslip seeded with live cancer cells.
A magnetic iron bead about 700 nanometres in diameter -- about 100 times smaller than the thickness of a human hair -- is placed on the coverslip, where the cancer cells easily take it up inside their membranes.
Once the bead is inside, Wang controls its position using real-time feedback from confocal microscopy imaging.
He uses a computer-controlled algorithm to vary the electrical current through each of the coils, shaping the magnetic field in three dimensions and coaxing the bead into any desired position within the cell.
"We can exert forces an order of magnitude higher than would be possible with lasers," said Wang.
In collaboration with Helen McNeil and Yonit Tsatskis at Mount Sinai Hospital in the US and colleagues, the team used the robotic system to study early-stage and later-stage bladder cancer cells.
Previous studies on cell nuclei required their extraction from cells. The researchers measured cell nuclei in intact cells without the need to break apart the cell membrane or cytoskeleton.
They were able to show that the nucleus is not equally stiff in all directions.
The researchers also measured exactly how much stiffer the nucleus got when prodded repeatedly, and determine which cell protein or proteins may play a role in controlling this response.
This knowledge could point the way toward new methods of diagnosing cancer, researchers said.
"We know that in the later-stage cells, the stiffening response is not as strong," said Wang.
"In situations where early-stage cancer cells and later-stage cells don't look very different morphologically, this provides another way of telling them apart," he said.
"You could imagine bringing in whole swarms of these nano-bots, and using them to either starve a tumour by blocking the blood vessels into the tumour, or destroy it directly via mechanical ablation," said Professor Yu Sun from the University of Toronto.
"This would offer a way to treat cancers that are resistant to chemotherapy, radiotherapy and immunotherapy," Sun said.