What is it like to be on the nanoscale, the size thousands of times thinner than a human hair? This is what an esteemed panel, moderated by Robert Krulwich, focused on throughout Cellular Surgeons: The New Era of Nanomedicine.
Peter Hoffman, a panelist who wrote a book on molecular machines making order from chaos, tried to paint a picture of a very different world. Imagine a place where gravity is a non-issue and you are constantly bombarded by high-speed particles coming from random directions. Water, which a swimmer can glide through easily, is thick and sticky. “It’s like a car being pummeled by 7,000-mph winds. Or a jet fighter crashing into something at a short distance, bouncing off, and crashing into something else,” Hoffman said. Even stranger, what matters on the nanoscale is not what the materials are made of, but how surface areas interact with each other. On the nanoscale, you can definitely judge things by their cover.
Surprisingly, this world is also extremely energy efficient. Humans, who eat food to turn into fuel, really only use about 120 watts per day, as much as a household light bulb. Digesting the food and breaking it down to the nanoscale allows you to use the energy in smarter ways. “If you’re that small, you can easily convert the different types of energy into each other, that’s only possible on the nanoscale,” Hoffman said.
He showed some videos of sophisticated machines in our bodies, molecules called kinase that sew up tissue fibers, tiny garbage men that selectively pick up unwanted material, and even a real microscopic video of a protein machine walking across an actin fiber.
Now, scientists are trying to design their own molecular machines. How are they going to keep up with millions of years of evolution that created the machines inside our body? Metin Sitti, a professor at Carnegie Melon who works on medical nanorobots explained, “As human beings, we are now going beyond nature, as engineers, as scientists. We don’t have the same constraints it has. We have the luxury and knowledge to play with these systems.”
Sitti presented one of his creations to the panel: a robot that rolls around in a patient who swallows it, capable of performing tissue biopsies and dispensing drugs at will. The robot rolls around the stomach, controlled by a magnet from outside the body. Sitti and his team came up with the soft, biodegradable body for the robot to make it more comfortable to use. Right now they are testing the bots on pigs.
Another panelist, Harvard biomedical professor and entrepreneur Omid Farokhzad, created a nanoparticle that carries drugs and attaches to specific receptors on a tumor’s surface. The tumor then engulfs it, in Trojan Horse style, and meets its demise. The particle also disguises itself from the immune system by coating itself with water. As it journeys through your body, it veers toward tumors by sensing their leaky blood vessels.
As for the risks involved with nanotechnology the panel was optimistic but careful.
“All of the revolutionary changes in medicine with an enormous amount of sentiment about what the long-term consequences of our actions world be, look at radiation, genetic modification,” Farokhzad said. “If there’s a nanoparticle treatment to enhance life for, let’s say, someone who has pancreatic cancer, is that the right trade off?”
The impacts of nanoparticles are still largely unknown, which we will learn about along the way. Yet, the panelists agree that testing new, better treatment and working to make them safe is the most important part.