Medical Nanomachines: Potential Boon or Bane?

 

One of the more unlikely premises for a movie was the idea behind the 1966 film Fantastic Voyage.  A scientist who plays a crucial role in the Cold War is stricken by a blood clot, and his own invention—a way to shrink objects to microscopic size for only an hour—is applied to a submarine full of people who then travel through his bloodstream to save him. 

 

Science fiction has a way of becoming reality, and while nobody has yet figured out how to shrink people and submarines, a recent New Yorker profile of the work of chemist James Tour and his colleagues describes microscopic light-powered jackhammers that can penetrate bacteria cell walls. 

 

In the first place, living cells are fantastically complex machines in their own right, so there is nothing intrinsically new about tiny machines.  The innovation claimed by Tour and his team is that they have developed a way to control the action of tiny jackhammer-like molecules by irradiating them with a specific wavelength of near-infrared light.  The molecules have what are called plasmons in them.  The details are complicated, but basically the plasmon acts like a kind of molecular tuning fork that resonates at one particular wavelength.  When light of that wavelength hits the molecule, it absorbs a great deal of energy and begins to vibrate vigorously, punching a hole in the bacterial wall and initiating the bacteria's demise.  And in contrast to shorter wavelengths of light in the visible range, near-infrared light can penetrate an inch or two into the body, allowing access to fairly deep regions under the skin.

 

So far, no human tests have been done.  Some moth larvae in Tour's lab have been treated with molecular jackhammers to save them from a terrible death from MRSA bacteria, but that's about it so far.  Years of testing with increasingly complicated organisms—mice, pigs, and so on—lies ahead before any practical applications to humans can be expected.  And there may be some bump in the road ahead that will prevent this technology from finding any application in humans at all.  But so far it looks promising, and I'm sure Prof. Tour will have no problem finding funding for more research, and commercial applications too if he's interested.

 

The article's author Dhruv Khullar mentions that some researchers are concerned about the inherent dangers of molecular machines.  He describes the "gray-goo" problem posed by an early futurist, K. Eric Drexler, who speculated that if a nanomachine was programmed to turn every living thing into more of itself, it might infect the whole biosphere.  This reminds me of what happened to some goldfish my mother bought us when we were kids, after giving in to our continual begging for them.  The fish were fine for a while, but one morning we got up and instead of goldfish, there were just floating lumps of whitish gunk in the tank.  She got rid of the aquarium soon after that, and we never had any more fish unless they were cooked first.

 

Tour's devices don't seem to pose such a hazard, because without the special near-IR wavelength of light shining on them, they don't do anything.  So that seems to be a pretty safe way to control them, unless you start speculating about how you might sneak some molecular jackhammers into a victim's drink, and then take them into a room bathed with the requisite wavelength of near-IR light, which is invisible, of course.  And there you go with another science-fiction suspense film.

 

It seems to me that activities such as Tour's are pretty harmless compared to, for instance, tinkering with existing coronaviruses with gain-of-function research.  For whatever reason, nature has produced (or God has allowed, depending on your point of view) some really nasty viruses that use mechanical means to take over cells and turn them into virus factories, with the byproduct of making the host ill or dead.  I was unable to locate the details, but someone once told me that the rabies virus is precisely designed with a kind of spear that penetrates neurons to infect them.  So in developing his molecular jackhammers, Prof. Tour isn't inventing as much as he is co-opting a technique and powering it by other means, namely light waves.  And arranging things so that the molecules can't do anything without external illumination is a nice fail-safe feature that allows the researcher to exert control.

 

This work is only one example of the discoveries scientists and engineers can make when provided with enough resources and cultural favor.  Not every country in the world is hospitable to scientific research of this type.  And it takes money and smart people, which are both limited resources.  We should not take such activities for granted, because they don't happen automatically.  It's easy to assume that medical technology will just keep on advancing on its own without anybody other than the researchers paying much attention. 

 

But there is a big threat to all U. S.-government-funded research looming on the horizon.  While the U. S. has never experienced a fiscal crisis such as the one that struck Germany in the early 1920s, nothing says we are immune from it.  As interest rates rise and the population ages, two money sinks—interest on the national debt and entitlements such as Social Security and Medicare—threaten to take over the Federal budget and squeeze out just about everything else.  While private funding has increasingly taken up the slack vacated by declining government support for research, it's hard to imagine a healthy private sector persisting if the government has gone bankrupt. 

 

And such events are not that predictable.  Neither major political party currently has the intestinal fortitude to address this issue with anything near the seriousness it deserves.  As things stand, there is still enough research money available to support impressive efforts such as the things Prof. Tour and his group are doing.  But if we are to see any practical benefits from it, there are years of work ahead, work that somebody has to do and somebody else has to pay for.  Smart young people will have to decide that research is worth doing, and the public will have to decide that it's worth paying for, and worth having a fiscally sound government to pay for it.  So far, it's all working, but whatever can't go on forever eventually has to stop.

 

Sources:  The New Yorker of June 24, 2024 carried Dhruv Khullar's article "Small Wonder" on pp. 20-23.  I also referred to a Rice University post on Prof. Tour's research at https://news.rice.edu/news/2023/molecular-jackhammers-good-vibrations-eradicate-cancer-cells

and Wikipedia articles on plasmons and molecular machines. 

 

What Could Go Wrong With Engineered Life Forms?

 

That question left the hypothetical realm for reality when Michael Levin, director of the Center for Regenerative and Developmental Biology at Tufts University, and Josh Bongard, professor of computer science at the University of Vermont, teamed together to turn frog stem cells into robots.  During the robots' seven-day lifetime, they can move, collect small particles into piles, and even reproduce after a fashion.  Developed with the essential assistance of an artificial-intelligence supercomputer, the new entities—called "xenobots" after the Latin name of the frog species from which the cells were taken—are the first step in a long-anticipated field that has up to now existed only in the realms of dystopian science fiction.

 

Starting with knowledge of what frog skin and cardiac cells can do, the scientists tried billions of different combinations of cells in the computer to see which ones could do interesting things.  The computer eventually came up with recipes for the assembly of hundreds of cells, which the scientists then carried out in the laboratory in a finicky process like assembling microscopic Legos, only the Legos are incubated frog stem cells.  The resulting robots did indeed move around, carry small objects in custom-designed pouches, and a Pac-Man-shaped version could even reproduce, spitting out a smaller version of itself every now and then. 

 

Asked about the ethical implications of their research, Levin said, "When we start to mess around with complex systems that we don't understand, we're going to get unintended consequences."  Bomgard added, "There's all of this innate creativity in life. . . . We want to understand that more deeply—and how we can direct and push it toward new forms."

 

Levin and Bomgard are working scientists, not philosophers, so when they talk out of school, so to speak, addressing not the technicalities of AI-driven biological multicell-organism fabrication, but the wider implications of their work, they tend to say things that are not particularly profound or original.  Anyone who has had trouble driving an unfamiliar rental car has learned that messing around with complex systems that we don't understand can have unintended consequences.  The question is not whether unintended consequences will happen—they will—but what you do about them if they do, and how you keep the bad ones from hurting yourself or others.

 

What Bomgard said encapsulates three streams of philosophy and religion that have been flowing since prehistoric times.  The first stream is the wonder one feels at the awesome abundance and variety of life on Earth.  "Innate creativity" implies that it's simply there somehow, a brute fact of existence that Bomgard uses the passive voice for ("There is . . . creativity.")  This ignores the fact that in every other area of human endeavor—music, art, literature, and science itself—creativity appears to arise only from human intelligence.  The elaborate architecture of termite nests, in which somehow thousands of individually unintelligent creatures cooperate to build sophisticated towers and walls, is sometimes called "creative," but is more realistically categorized as instinct.  No termite colony has ever built a Corinthian column.  It takes human ingenuity to do that.

 

No reasonable scientist can deny that there is a creative spirit or principle in life, but the universally-observed prohibition on talking about God in this connection forces them simply to say it's out there without saying where it came from.  But a failure to acknowledge the source of all that creativity may lead to something worse than unintended consequences later on.

 

The second great stream of philosophy is the human desire to know, as Aristotle points out in the first words of his Metaphysics:  "All men by nature desire to know."  Bomgard echoes this when he says "We want to understand that more deeply," meaning the creativity of life.  Up to the time of Sir Francis Bacon, philosophers sought wisdom as the highest secular good.  But since Bacon, the unadulterated desire simply to know something has been subordinated most of the time to the third great stream of philosophical inquiry:  how can we use this knowledge to, in Bacon's words, "better man's estate"? 

 

In more prosaic terms, the difference between the two streams is the distinction between pure and applied science, although the distinction is often more hypothetical than real.  Ask any mathematician who has spent years pursuing a theory simply because it was beautiful and interesting, and then turns around to discover that the National Security Agency has made it an essential part of their latest encryption technology.  The fact is, pure science can turn into applied science at any time, and a lot of applied science has accidentally led to advances in pure science as well.

 

But that ignores the question of intent, which is the critical question that so far has remained unanswered, at least by Levin and Bomgard.  I will admit that the first thing I thought of when I read about what they were doing is a phrase first used by Eric Drexler in his 1986 book Engines of Creation, a half-science and half-fiction speculation on the future of nanotechnology.  Gray goo is what the world would turn into if we managed to develop a type of bacteria that could live and multiply by consuming almost anything.  Readers will recognize the xenobot as possibly a first necessary step in making gray goo.

 

Levin and Bomgard say there is no chance their modified frog embryo cells will escape the lab, as they can't live outside the specially prepared soup that they were incubated in, and when they die they are as harmless as the thousands of skin cells each of us shed from our bodies every day.  Well, maybe so.  But the same curiosity and "if we can do it, we must do it" attitude that drove these researchers to make their xenobots can (I don't say will) lead to the kind of disasters that we've seen in the last couple of years.  We may never know whether COVID-19 originated in a lab accident in Wuhan or by natural means.  But even the remote possibility that it was man-made should make us all take very hard and long looks at efforts to manipulate living things in a way that could lead to harm, even if it is accidental.

 

Sources:  CNN carried the article "World's first living robots can now reproduce, scientists say" by Katie Hunt on Nov. 29, 2021 at https://www.cnn.com/2021/11/29/americas/xenobots-self-replicating-robots-scn/index.html.  I also referred to the University of Vermont press release on the research at https://www.uvm.edu/news/story/team-builds-first-living-robots, and the Wikipedia article on gray goo.