NANOBOTS TO THE RESCUE

Image courtesy of ASU Biodesign Institute

The invention of the microscope might not have started humankind’s interest in the study of very small things, but it certainly provided a major boost. Within the past century we’ve seen advancements like the electron scanning microscope that enables scientists to not only see atomic-sized objects but also manipulate them, and chemical technologies like CRISPR/Cas9 used to edit living genes. Nanoscience is making significant progress in medical fields, including  the prospect of some day having robotic devices too small to see programmed to circulate through our bloodstream and keep us healthy.

Maybe that idea was inspired by the 1966 movie Fantastic Voyage which featured a team of scientists in a submarine shrunk down to microscopic size, racing through a bloodstream to dissolve a potentially fatal blood clot and save a man’s life. Loving that idea (but reluctant to write about shrink rays) I wrote a (so-far-unpublished) novel and published a prequel story to it called “Shakedown” that featured a nano-scale submersible piloted remotely through the bloodstream using virtual reality. You can read “Shakedown” here. While both stories are science fiction, the reality is coming closer than ever.

New work performed by Arizona State University along with China’s National Center for Nanoscience and Technology is an astonishing step forward.

Cancer tumours are like other living tissue in that they need circulation of blood to survive. They have their own blood vessels, just like our skin and organs. So what if you could cut off that blood supply to a tumour without harming healthy cells around it?

Great idea—the problem is how to do it. We know that an enzyme called thrombin is used by the body to seal wounds and keep our blood from leaking out. Thrombin binds a substance called fibrin with platelets to produce clotting at the wound. A good thing. Mind you, blood clots in the wrong places can be deadly to tissues, causing embolisms and possibly strokes. A bad thing. Unless you could find a way to cause blood clots only in the blood vessels of cancer tumours.

That’s what the Arizona  and Chinese scientists have done, and in a brilliant way.

They had to solve two problems: how to deliver thrombin through the bloodstream to the site of the tumour, and how to keep it from accidentally affecting blood vessels of healthy tissue. The delivery system they developed uses DNA—yes, the stuff in our genes that carries the information that makes our bodies the way they are. Turns out DNA can be folded in lots of ways. So these scientists have performed DNA origami, making little DNA tubes with thrombin molecules inside them. Kind of like a tube of tennis balls. Then, to make sure this special package gets delivered only to the right address, they attached a chemical called a DNA aptamer that’s attracted to a protein only found on the surface of the tumour cells, not on healthy cells.

Apparently, the system has worked well in tumours in mice, producing substantial blockages and the consequent deaths of the tumour cells.

You’ll know by now that lots of work remains to be done before the technique can be used on humans, but there’s no reason to believe it won’t happen. And that’s just one example of the progress being made. Maybe, you’ll quibble, a folded tube of DNA isn’t exactly a robot, and a chemical bonding agent can’t truly be called “programming”. Well, I think that will come too, someday. In the meantime, every new nano-medical success is something worth celebrating.

IS OUR ELECTRONIC CIVILIZATION TOO VULNERABLE?

2012 Coronal Mass Ejection (solar superstorm)

In the 2003 movie The Core Earth’s molten core stops spinning, which causes the planet’s magnetic field to fail and disaster ensues. A team of brilliant scientists (played by some good actors like Aaron Eckhart and Hilary Swank) uses a giant burrowing machine to drill down to the core and explode nuclear warheads to restart the circulation. It’s a plot you’d expect from a 1950’s B-movie, and that’s probably why I like it, but it’s generally considered a ‘guilty pleasure’ movie at best. Still, it got some things right. A weakening of our magnetic field could leave our electronics-based civilization frighteningly vulnerable, and threaten most life on Earth. A complete loss would be disastrous. And some scientists are raising the alarm.

Maybe you did experiments with magnets and iron filings in school, or maybe you’ve just seen drawings of a magnetic field—curved lines around the magnet that curl in and touch the positive and negative poles at each end. In Earth’s case, the north and south poles. Our planet is like a ball in the middle of a giant invisible doughnut. Without that field, we couldn’t live here, and it may be in danger of collapse.

It isn’t because the Earth’s core has shown signs of stopping. No, the concern comes from the fact that we know from geological records (indicators in ancient rock) that the magnetic field has switched poles pretty often during Earth’s history. North becomes South and the magnetic flow reverses. Though the time between such flips varies a lot, it’s averaged about every 200,000 to 300,000 years, and it’s been 780,000 years since the last one so some scientists say we’re overdue.

So what’s the big deal? Your compass reads north when you’re facing south, and some migratory birds get confused? Sure, but it’s what happens during the transition that’s the problem. You guessed it: the magnetic field is significantly weakened—possibly reduced to as little as ten percent of its usual strength at times. And the pole reversal isn’t quick, like flicking a switch. Indications from rock layers show that it might take thousands of years. The unreliability of a compass heading will be the least of our worries.

What makes the Earth’s magnetic field so critical is that it protects the planet’s surface from a bombardment of high-energy particles from space that can wreck DNA in living organisms (causing mutations and cancers, or even quicker cell deaths) and overloads electric wiring and electronic circuitry. That bombardment is happening all the time, but it gets much worse when our sun has indigestion. Solar storms send out mammoth flares of high-energy X-rays and particles plus ionized gases that can really mess up our communications and power grids. A flare in March of 1989 knocked out power all across the Canadian province of Quebec, but it was much smaller than an event recorded back in 1859 when telegraph wires were first spreading over the continents. Known as the Carrington event, that one was so powerful that the northern lights were seen as far south as Tahiti and Cuba. Not only did overloaded equipment fail under the strain, many of the telegraph cables themselves caught fire! And that was with the planet’s protective magnetic field at full strength.

As recently as 2012 a solar storm at least as powerful as the 1859 event sprayed deadly energy out into space, but we dodged that bullet—the storm was on a part of the sun facing away from Earth. A week or ten days earlier, it would have hit us. Here's a good NASA video about the near miss and what could have happened. Now imagine if it had hit us when the magnetic poles had begun a reversal and the Earth’s shielding was at only ten percent of normal.

It’s not a pretty picture. Ionized particles would fry the circuitry of satellites. Magnetic induction would produce enormous amounts of electric current throughout our power grids, blowing transformers and other equipment everywhere exposed to the blast. And since we just don’t have huge numbers of spare transformers lying around, some analysts estimate our civilization could be knocked back to Victorian times.

That’s a worst case scenario raised in the recently published The Spinning Magnet by journalist Alanna Mitchell, and mentioned elsewhere. Others strenuously downplay the danger, although even they admit that we would do well to prepare for fluctuations in the strength of the magnetic field by fortifying our power grids and technological infrastructure.

Whether such a crisis is imminent or not, it sure provides fodder for some juicy disaster fiction! (But solid SF writers, please. Not Hollywood—they just don’t seem to know the difference between meaty and cheesy.)