Medical Device Daily National Editor
Physics and chemistry have given us considerable understanding concerning the various things that push and pull the physical world around us: why things grab or have friction, or why they slip and slide; gravity forcing things down, centrifugal forces throwing out; the pressure of air and nature's dislike of a vacuum; electrical polarity and magnetic forces that push things apart or pull them together.
These are the common forces of the everyday macro world that we have learned to use in creating machines, and in the drugs and devices of medicine.
But a new world of machines is coming, a tiny world, a nano-world, with many of these machines targeted for the medical future.
The nano-futurists have told us that these medical machines, such as nano-bots and other incredibly small mechanical systems, will be used to perform a variety of intricate duties within the body, from, say, distributing drugs at a specific time, to a very specific place, to patching up damaged strands of DNA, or to track down and kill viruses or rogue cells.
And, so far, the assumption has been that the push/pull forces of this nano world are the same as those in the micro world.
Not so – or at least not always so, or exactly so – is the suggestion of a study describing a groundbreaking method for manipulating something called the Casimer-Lifshitz effect. In their work, the researchers "levitated" molecules, reversing the effect which usually serves to bring molecules together in the nano-scale world.
The research – reported last week in the journal Nature – was developed in a teamwork collaboration among Adrian Parsegian, PhD, head of the Section on Molecular Biophysics at the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) of the National Institute of Health, and Jeremy Munday and Federico Capasso of Harvard University (Cambridge, Massachusetts).
In their study, the researchers brought a tiny gold-plated sphere in contact with a flat glass surface, separating them with a liquid known as bromobenzene, most often used in drug development.
At close distances, the molecular forces of the two surfaces, when in the presence of bromobenzene, repelled each other, so that the molecules of gold and glass never came in direct contact with each other and were separated by a few nanometers.
The Casimer-Lifshitz effect, a combination of theoretical approaches developed by Hendrik Casimer and Evgeny Lifshitz, is used to explain the quantum forces that both pull molecules together but also may be used to push them apart.
Thus far, the emphasis has been primarily on the forces of attraction described by this effect, most often as a matter of establishing the variables of this effect.
But as the elements of nano-machines have become smaller, these attractive effects been tend to fuse the molecular structures involved, thus driving the pursuit of research in how they can be successfully manipulated and engineered for various applications.
The achievement of levitated molecules suggests the macro-world use of magnets to levitate, say, the spinning rotors found in advanced generation ventricular assist devices (VADs), but Parsegian told Medical Device Daily that "these forces [employed in the Nature study] are different, on a different scale, way down to the nano level" and that understanding them is essential to the creation of machinery in this new nanotech world.
Rather than offering nanotechnology developers an immediate pathway to new nano-products, Parsegian said that the study, though very preliminary, is an "encouraging step."
Its primary benefit, he said, is "to help people think about design" of such products. "If you're not even aware of these forces or how they are organizing material, you're not putting them into your thinking and design."
"The emerging technology of nanomechanics has the potential to improve medicine and other fields," said Duane Alexander, MD, director of the NICHD. "By reducing the friction that hinders motion and contributes to wear and tear, the new technique provides a theoretical means for improving machinery at the microscopic and even molecular level."
Parsagian also emphasized to MDD that the work was important in its use of a collaborative approach, and he suggested that, today, research is often hampered by the increasing decree of scientific specialization into silos.
"I think the big point is that you really need to mix different kinds of learning, different kinds of study" to create the kinds of research breakthroughs represented by the new study.
Thus, while he noted his affiliation with the NIH – which tend to focus on the clinical applications of science – he said he was "allowed to work" in the area of pure physics as a key part of this collaboration.
The result of these kinds of collaborations, he said, has "enormous financial benefits to the economy – the reach we're talking about impacts all kinds of industries."
He added: "It's not something you plan, it's something you see happen" and "the intellectual leaps are so huge."
The crux of this molecular research, Parsagian said, has demonstrated the ability to utilize "weak electrostatic forces" and "charged fluctuation forces."
Now, the next step will be to go beyond this "neat effect – I want to see a lot more measurements of this kind, with systematic variation of conditions."
He acknowledged that the systematization of new knowledge is "boring," But he said that this process is "this wonderful step the human race takes – you start with science [to reach] the literacy of the physics."