…
In what fields would APM cause the most pronounced economic disruption and the collapse of global supply chains to more local chains?

The digital revolution had far-reaching effects on information industries. APM-based production promises to have similarly far-reaching effects, but transposed into the world of physical products. In thinking about implications for international trade and economic organization, three aspects should be kept in mind: a shift from scarce to common raw materials, a shift from long supply chains to more direct paths from raw materials to finished products, and a shift toward flexible, localized manufacturing based on production systems with capabilities that are comparable on-demand printing. This is enough to at least suggest the scope of the changes to expect from a mature form of APM-based production — which again is a clear prospect but emphatically not around the corner.
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-Posted by Stephanie C

Harmless bacteria could be re-engineered into microscopic factories that could, in addition to more immediate applications, perhaps provide components for more general molecular manufacturing systems. (credit Imperial College, London)

Synthetic biology and molecular manufacturing/productive nanosystems have in common the effort to rationally engineer systems to make and assemble parts for complex molecular machine systems. The effort in synthetic biology to design complex biological systems in a hierarchical architecture from well-characterized molecular parts is accelerating. A hat tip to ScienceDaily for reprinting this Imperial College news release “Discovery in synthetic biology a step closer to new industrial revolution“:

Scientists report that they have developed a method that cuts down the time it takes to make new ‘parts’ for microscopic biological factories from 2 days to only 6 hours.

The scientists, from Imperial College London, say their research brings them another step closer to a new kind of industrial revolution, where parts for these biological factories could be mass-produced. These factories have a wealth of applications including better drug delivery treatments for patients, enhancements in the way that minerals are mined from deep underground and advances in the production of biofuels.

Professor Paul Freemont, Co- Director of the Centre for Synthetic Biology and Innovation at Imperial College London and principal co-investigator of the study, which is published today in the journal Nucleic Acids Research [abstract, free full text PDF], says:

“Before the industrial revolution most items were made by hand, which meant that they were slower to manufacture, more expensive to produce and limited in number. We are at a similar juncture in synthetic biology, having to test and build each part from scratch, which is a long and slow process. We demonstrate in our study a new method that could help to rapidly scale up the production and testing of biological parts.”

Parts made up of DNA are re-engineered by scientists and put into cells to make biological factories. However, a major bottleneck in synthetic biology is the lack of parts from which to build new types of factories. To build parts using the current time-consuming method, scientists have to re-engineer DNA in a cell and observe how it works. If it functions according to their specifications, then the scientists store the part specifications in a catalogue.

Now, scientists from Imperial College London have devised a much quicker method that does away with the need for them to re-engineer a cell every time they want to make a new part. The team say their work could lead to vast new libraries of off-the-shelf components that could be used to build more sophisticated biological factories.

James Chappell, co-author of the study from the Centre for Synthetic Biology and Innovation at Imperial College London, says:

“One of the major goals in synthetic biology is to find a way to industrialise our processes so that we can mass produce these biological factories much in the same way that industries such as car manufacturers mass produce vehicles in a factory line. This could unlock the potential of this field of science and enable us to develop much more sophisticated devices that could be used to improve many facets of society. Excitingly, our research takes us one step closer to this reality, providing a rapid way of developing new parts.”

When a cell is re-engineered, the re-programmed DNA in the cell encodes a message that is conveyed by molecules called messenger ribonucleic acid (mRNA) to the cell’s production factories called ribosomes. The ribosomes translate the genetic information into a command that instructs the cell to perform functions. For example, scientists can already re-engineer a cell into an infection detector factory, which produces a protein that detects chemical signals from human pathogenic bacteria and changes colour to indicate their presence.

In the study, the Imperial researchers demonstrate for the first time that the same method can be achieved in a test tube outside of a cell. This involves extracting from cells the machinery that produces mRNA and proteins and providing the energy and building blocks to help them survive in test tubes. The team then add their re-programmed DNA to the solution and observe how it functions.

The advantage of this method is that scientists can develop litres of this cell-like environment so that multiple re-programmed DNA can be tested simultaneously, which speeds up the production process of parts.

The next stage of the research is to expand the types of parts and devices that can be developed using this method. They also are aiming to develop a method using robots to speed up and make the whole process automated.

Professor Richard Kitney, co- Director of the Centre for Synthetic Biology and Innovation at Imperial College London says: “Synthetic biology is seen by the British Government as having the potential to create new industries and jobs for the benefit of the UK economy. This work is part of a wider, major research programme within the Centre to develop technology that can be used across a range of industrial applications.”

The hope driving this research is that biological parts will transform industrial sectors like drug delivery and biofuels production into molecular manufacturing processes. Whether synthetic biology can eventually be made to contribute parts for nanofactories to implement more general molecular manufacturing using stronger, more rigid parts, remains to be seen.
—James Lewis, PhD

The new double-walled silicon nanotube anode is made by a clever four-step process: Polymer nanofibers (green) are made, then heated (with, and then without, air) until they are reduced to carbon (black). Silicon (light blue) is coated over the outside of the carbon fibers. Finally, heating in air drives off the carbon and creates the tube as well as the clamping oxide layer (red). (Image courtesy Hui Wu, Stanford, and Yi Cui)

A clever new method for making hollow silicon nanostructures produces a battery anode that is not quickly destroyed by the stress of repeated charging and discharging. A hat tip to PhysOrd.com for reprinting this SLAC National Accelerator Laboratory news release written by Mike Ross “New nanostructure for batteries keeps going and going“:

For more than a decade, scientists have tried to improve lithium-based batteries by replacing the graphite in one terminal with silicon, which can store 10 times more charge. But after just a few charge/discharge cycles, the silicon structure would crack and crumble, rendering the battery useless.

Now a team led by materials scientist Yi Cui of Stanford and SLAC has found a solution: a cleverly designed double-walled nanostructure that lasts more than 6,000 cycles, far more than needed by electric vehicles or mobile electronics.

“This is a very exciting development toward our goal of creating smaller, lighter and longer-lasting batteries than are available today,” Cui said. The results were published March 25 in Nature Nanotechnology [abstract].

Lithium-ion batteries are widely used to power devices from electric vehicles to portable electronics because they can store a relatively large amount of energy in a relatively lightweight package. The battery works by controlling the flow of lithium ions through a fluid electrolyte between its two terminals, called the anode and cathode.

The promise – and peril – of using silicon as the anode in these batteries comes from the way the lithium ions bond with the anode during the charging cycle. Up to four lithium ions bind to each of the atoms in a silicon anode – compared to just one for every six carbon atoms in today’s graphite anode – which allows it to store much more charge.

However, it also swells the anode to as much as four times its initial volume. What’s more, some of the electrolyte reacts with the silicon, coating it and inhibiting further charging. When lithium flows out of the anode during discharge, the anode shrinks back to its original size and the coating cracks, exposing fresh silicon to the electrolyte.

Within just a few cycles, the strain of expansion and contraction, combined with the electrolyte attack, destroys the anode through a process called “decrepitation.”

Over the past five years, Cui’s group has progressively improved the durability of silicon anodes by making them out of nanowires and then hollow silicon nanoparticles. His latest design consists of a double-walled silicon nanotube coated with a thin layer of silicon oxide, a very tough ceramic material.

This strong outer layer keeps the outside wall of the nanotube from expanding, so it stays intact. Instead, the silicon swells harmlessly into the hollow interior, which is also too small for electrolyte molecules to enter. After the first charging cycle, it operates for more than 6,000 cycles with 85 percent capacity remaining.

Cui said future research is aimed at simplifying the process for making the double-wall silicon nanotubes. Others in his group are developing new high-performance cathodes to combine with the new anode to form a battery with five times the performance of today’s lithium-ion technology.

In 2008, Cui founded a company, Amprius, which licensed rights to Stanford’s patents for his silicon nanowire anode technology. Its near-term goal is to produce a battery with double the energy density of today’s lithium-ion batteries.

With a clever new method to produce novel nanostructures, a material like silicon, which has been very well studied for half a century as the basis for an important technology, can fill unexpected new roles. A few decades from now, when atomically precise manufacturing provides a general method for making arbitrarily complex nanostructures, we can expect many more surprising developments.
—James Lewis, PhD

Rice University graduate student Daniel Hashim burns oil out of a sponge-like material made of carbon nanotubes and a dash of boron. The sponge can soak up oil, which can then be burned off and the sponge reused. (Credit: Jeff Fitlow/Rice University)

A new technique that dopes carbon nanotubes with boron atoms provides new evidence of the enormous practical utility of improving methods to control the structure of matter at the nanometer scale, even if the control is not yet atomically precise. A hat tip to ScienceDaily for reprinting this Rice University news release written by Mike Williams “Nanosponges soak up oil again and again” (includes video):

Researchers at Rice University and Penn State University have discovered that adding a dash of boron to carbon while creating nanotubes turns them into solid, spongy, reusable blocks that have an astounding ability to absorb oil spilled in water.

That’s one of a range of potential innovations for the material created in a single step. The team found for the first time that boron puts kinks and elbows into the nanotubes as they grow and promotes the formation of covalent bonds, which give the sponges their robust qualities.

The researchers, who collaborated with peers in labs around the nation and in Spain, Belgium and Japan, revealed their discovery in Nature’s online open-access journal Scientific Reports ["Covalently bonded three-dimensional carbon nanotube solids via boron induced nanojunctions"].

Lead author Daniel Hashim, a graduate student in the Rice lab of materials scientist Pulickel Ajayan, said the blocks are both superhydrophobic (they hate water, so they float really well) and oleophilic (they love oil). The nanosponges, which are more than 99 percent air, also conduct electricity and can easily be manipulated with magnets.

To demonstrate, Hashim dropped the sponge into a dish of water with used motor oil floating on top. The sponge soaked it up. He then put a match to the material, burned off the oil and returned the sponge to the water to absorb more. The robust sponge can be used repeatedly and stands up to abuse; he said a sample remained elastic after about 10,000 compressions in the lab. The sponge can also store the oil for later retrieval, he said.

“These samples can be made pretty large and can be easily scaled up,” said Hashim, holding a half-inch square block of billions of nanotubes. “They’re super-low density, so the available volume is large. That’s why the uptake of oil can be so high.” He said the sponges described in the paper can absorb more than a hundred times their weight in oil.

Ajayan, Rice’s Benjamin M. and Mary Greenwood Anderson Professor in Mechanical Engineering and Materials Science and of chemistry, said multiwalled carbon nanotubes grown on a substrate via chemical vapor deposition usually stand up straight without any real connections to their neighbors. But the boron-introduced defects induced the nanotubes to bond at the atomic level, which tangled them into a complex network. Nanotube sponges with oil-absorbing potential have been made before, but this is the first time the covalent junctions between nanotubes in such solids have been convincingly demonstrated, he said.

“The interactions happen as they grow, and the material comes out of the furnace as a solid,” Ajayan said. “People have made nanotube solids via post-growth processing but without proper covalent connections. The advantage here is that the material is directly created during growth and comes out as a cross-linked porous network.

“It’s easy for us to make nano building blocks, but getting to the macroscale has been tough,” he said. “The nanotubes have to connect either through some clever way of creating topological defects, or they have to be welded together.” …

In this case, a scaleable method to introduce a few boron atoms while growing carbon nanotubes produces a novel molecular architecture with amazing and useful properties. Whether or not this specific technique adds to the toolkit that will eventually produce atomically precise manufacturing, it contributes a product that increases incentives for developing ever more precise methods of controlling the structure of matter at the nanometer scale.
—James Lewis, PhD

A major problem plaguing the wind energy industry is the inability of current manufacturing materials used in wind turbine blades to keep up with increasing demand. Dr. Usama Younes and Dr. Serkan Unal of Bayer MaterialScience LLC plan to release the results of a study recently conducted by Bayer on its development of polyurethane turbine blades designed to withstand increased stress. The study discusses how the properties of carbon nanotubes improves the fracture toughness of the materials used in the blades. According to Dr. Younes,

“Incorporation of a small amount of multi-walled carbon nanotubes improves the fracture of both polyurethane and epoxy composites by as much as 48 percent. The addition of carbon nanotubes is a viable option to improve the strength of wind turbine blades.”

This development was made possible by a grant from the Department of Energy for the purposes of comparing current materials with newer polyurethane systems as well as for the development of stronger composites for turbine blades.

Source: Azonano. (2012). Carbon Nanotubes Improve Fracture Toughness of Polyurethane Composites for Wind Turbine Blades.

Respectfully,
Christopher William Ince Jr.

• What will be the next great revolution in the material basis of civilization?
• How can we establish reliable knowledge about key aspects of such technologies?

From the news release, aptly titled “The next technological revolution?“:

The key to tackling some of our planet’s greatest challenges may be found in the laws of physics and methods of engineering, as opposed to any specific technological innovation.

Speaking at the inaugural public lecture of the Oxford Martin Programme on the Impacts of Future Technology, Dr Eric Drexler said there is a compelling case for the viability of atomically precise manufacturing. This is the process of building structures, tools and machines starting at the molecular level, with atomic precision, to address challenges such as rising greenhouse gases and energy production for our growing population.

In a talk entitled “Exploring a Timeless Landscape: Physical Law and the Future of Nanotechnology”, pioneering nanotechnology researcher Dr. Drexler invited the audience to consider the intriguing possibility of nano-level manufacture of macro-level products. Such a process, if achieved, would be the next great revolution in the material basis of civilization, offering high-performance components, materials or systems and accelerated productivity. …

Those who have read Drexler’s 1988 essay on exploratory engineering and the 2007 Technology Roadmap for Productive Nanosystems will be familiar with the main arguments presented in the talk. Dr. Drexler’s conclusions about the development of atomically precise manufacturing were:

• We now have ample scientific knowledge. Rather than additional breakthroughs we need component design.
• Molecular experiments are fast and inexpensive by ordinary engineering standards.
• Advances in fabrication methods will yield faster more predictable results, accelerating progress.

Dr. Drexler left the audience to consider whether the advent of atomically precise manufacturing meant that in preparing for the 21st century we should expect scarcity and conflict or something radically different, and whether we could change the conversation in the world about the future incrementally in a well-grounded way.

The Oxford Martin Programme has made the abstract available, which includes a link to a Youtube video of the lecture “Timeless Landscape: Physical Law and the Future of Nanotechnology“.

MIT researchers use genetically modified virus to produce structures that improve solar-cell efficiency by nearly one-third.

Researchers at MIT have found a way to make significant improvements to the power-conversion efficiency of solar cells by enlisting the services of tiny viruses to perform detailed assembly work at the microscopic level.

In a solar cell, sunlight hits a light-harvesting material, causing it to release electrons that can be harnessed to produce an electric current. The new MIT research, published online this week in the journal Nature Nanotechnology [abstract], is based on findings that carbon nanotubes — microscopic, hollow cylinders of pure carbon — can enhance the efficiency of electron collection from a solar cell’s surface.

Previous attempts to use the nanotubes, however, had been thwarted by two problems. First, the making of carbon nanotubes generally produces a mix of two types, some of which act as semiconductors (sometimes allowing an electric current to flow, sometimes not) or metals (which act like wires, allowing current to flow easily). The new research, for the first time, showed that the effects of these two types tend to be different, because the semiconducting nanotubes can enhance the performance of solar cells, but the metallic ones have the opposite effect. Second, nanotubes tend to clump together, which reduces their effectiveness.

And that’s where viruses come to the rescue. Graduate students Xiangnan Dang and Hyunjung Yi — working with Angela Belcher, the W. M. Keck Professor of Energy, and several other researchers — found that a genetically engineered version of a virus called M13, which normally infects bacteria, can be used to control the arrangement of the nanotubes on a surface, keeping the tubes separate so they can’t short out the circuits, and keeping the tubes apart so they don’t clump.

The system the researchers tested used a type of solar cell known as dye-sensitized solar cells, a lightweight and inexpensive type where the active layer is composed of titanium dioxide, rather than the silicon used in conventional solar cells. But the same technique could be applied to other types as well, including quantum-dot and organic solar cells, the researchers say. In their tests, adding the virus-built structures enhanced the power conversion efficiency to 10.6 percent from 8 percent — almost a one-third improvement.

This dramatic improvement takes place even though the viruses and the nanotubes make up only 0.1 percent by weight of the finished cell. “A little biology goes a long way,” Belcher says. With further work, the researchers think they can ramp up the efficiency even further.

The viruses are used to help improve one particular step in the process of converting sunlight to electricity. In a solar cell, the first step is for the energy of the light to knock electrons loose from the solar-cell material (usually silicon); then, those electrons need to be funneled toward a collector, from which they can form a current that flows to charge a battery or power a device. After that, they return to the original material, where the cycle can start again. The new system is intended to enhance the efficiency of the second step, helping the electrons find their way: Adding the carbon nanotubes to the cell “provides a more direct path to the current collector,” Belcher says.

The viruses actually perform two different functions in this process. First, they possess short proteins called peptides that can bind tightly to the carbon nanotubes, holding them in place and keeping them separated from each other. Each virus can hold five to 10 nanotubes, each of which is held firmly in place by about 300 of the virus’s peptide molecules. In addition, the virus was engineered to produce a coating of titanium dioxide (TiO2), a key ingredient for dye-sensitized solar cells, over each of the nanotubes, putting the titanium dioxide in close proximity to the wire-like nanotubes that carry the electrons.

The two functions are carried out in succession by the same virus, whose activity is “switched” from one function to the next by changing the acidity of its environment. This switching feature is an important new capability that has been demonstrated for the first time in this research, Belcher says.

In addition, the viruses make the nanotubes soluble in water, which makes it possible to incorporate the nanotubes into the solar cell using a water-based process that works at room temperature. …

Using a virus particle as the biomolecular framework does not enable individually addressing specific sites on the framework, as could be done with scaffolded DNA origami, so it doesn’t seem likely that this approach could be used to assemble systems complex enough for atomically precise manufacturing. On the other hand, this is a very neat demonstration of the MMCN principle for something simpler that might be very near to practical application.

Dear Nanodot,

Zyvex Technologies announced that its 54-foot‚ boat named Piranha completed sea trials near Puget Sound in the Pacific Ocean and demonstrated record fuel efficiency. After six months of extensive testing, the Piranha this morning completed its final sea trial; a 600-nautical mile, rough-weather test in the Pacific Ocean in Washington and Oregon.

Piranha finished the tests in time to travel to its debut at the Sea Air Space show in Washington, DC, on April 11th. There, defense contractors are evaluating the Piranha for use as an unmanned platform with a variety of mission applications, including anti-piracy, harbor patrol, and oceanographic surveying

A conventional aluminum or fiberglass boat would have consumed 50 gallons or more per hour, while test results prove that Piranha consumed only 12 gallons of fuel per hour while cruising at 25 knots. The Piranha demonstrates Zyvex Technologies‚ ability to produce products with nano-enhanced materials that are 40% stronger than metals, such as aluminum, and 75% lighter, resulting in increased fuel efficiency.

Zyvex produced Piranha in just 90 days. The makers believe it can help coastal city leaders in ports like Seattle, San Diego, Miami, Norfolk, and New York better protect their harbors. In 2009, the New York City Police Commissioner testified before Congress that even with the Coast Guard’s assistance, the department could not fully protect the harbor, especially considering the vast amounts of uninspected cargo that enters the Ports of New York and New Jersey, pointing out that Mumbai was just another reminder. Two years later, there is still an urgent need for better port and maritime security.

The recent Oman piracy tragedy for four Americans from Seattle underscores the need for additional civilian and commercial security. In addition to the U.S. Navy, unmanned surface vessels such as Piranha can be deployed by Customs and Border Patrol, Port authorities and harbor police in high risk areas. Pirates can be tracked over long ranges with a clear picture of location so commercial vessels can avoid them. Piranha is an alternative to costly aircraft carriers. With its range and endurance, military personnel could remain on station for weeks and still protect designated areas. Piranha can be leased as an escort for commercial or private sailors through dangerous areas.

Jackie
For Zyvex Technologies

For more, Piranha completes rough weather sea trials. See also PRWeb and at Zyvex Technologies.

…Intel CEO Paul Otellini has said “it costs $1 billion more per factory for me to build, equip, and operate a semiconductor manufacturing facility in the United States.” He has also said that not long ago “our research centers were without peer. No country was more attractive for start-up capital. We seemed a generation ahead of the rest of the world in information technology. That simply is no longer the case.”

Capital markets (and with them our leadership in IPOs) are fleeing the U.S., with the latest development being the acquisition of the NYSE by Deutsche Börse. Having learned nothing from the impact of punishing the innocent with Sarbanes-Oxley, Congress has unleashed an open-ended rulemaking frenzy under Dodd-Frank. Who knows what that will bring, but it’s a safe bet it will work out well for large organizations like GE while entrepreneurs and real innovators are losers again. And as always, tighter environmental regulations and data requirements are promised (ostensibly to ‘crack down’ on polluters, though the more likely result is that better replacement innovations simply won’t even be attempted). …

So despite the Einsteinian insanity of arguing yet again for sensible innovation policy, let’s connect all of this with why nanotechnology (other than via Moore’s Law, a battery, three protein/liposome/polymer cancer drugs, and some low-impact consumer applications) has not yet lived up to its hype, at least as measured by venture capital investment, successful investor exits (A123 and ???) and high-wage job creation in the U.S. (A123 and ???). …

Except for the biggest and lowest risk opportunities (e.g. better drop-in replacement batteries with one new component, blockbuster drugs) the process can’t even get going when small companies have to pay big company prices for regulatory compliance to access a small initial opportunity (consistent with limited ability to ramp production), and both investors and customers find the cost, risk and uncertainty hurdles too high to overcome. This is compounded by the worsening U.S. environment for startups and investors. It is small wonder, really, that the two-year old ‘recovery’ certainly doesn’t feel like one in the hardware/materials manufacturing sector.

But nanotechnology and nanomaterials, along with the production techniques to deliver them, are still new compared to the chemical industry, and there is still hope that badly needed societal innovation might occur in support of enabling their economic and social benefits. One thing that is clearly required is a far more enabling regime for startups and low-volume first applications. One possible scenario for this is a fast-track, light-regulatory-touch path for green nanotechnology: nanomaterials and nanomanufacturing developments conducted according to the principles of green chemistry. Another way to say this is safe-by-design (to the extent possible, based on what we know) products produced by green-by-design manufacturing processes.

Progress has been made on this vision, and we’re ready to discuss concrete criteria for what constitutes green nanotechnology, standard/simplified characterization protocols and enabling policies. And that’s exactly what we intend to do at GN11, Greener Nano 2011, May 2-3 at Hewlett-Packard’s Cupertino site in the heart of Silicon Valley. We’re assembling a great program and attendance of the right people and organizations to “Advance Applications and Reduce Risks” – including the risk of not innovating in the first place.

There is no time to lose, because other countries (especially in Asia) seem determined to win the opportunity to lead in 21st century manufacturing.

Skip Rung is certainly addressing an important problem. As someone who has followed nanotechnology closely since 1986, I have to say that, despite substantial advancements in nanoscience and nanotechnology, progress has been disappointing in two areas: (1) there has not been major investment in developing advanced nanotechnology (high throughput productive nanosytems) based on the Feynman vision as articulated by Eric Drexler, Ralph Merkle, and Robert Freitas; (2) advances in nanotechnology have not launched a large and rapidly growing nanotechnology industry in the way that advances in semiconductor manufacturing and integrated circuits launched the computer industry. A vibrant industry focused on near- and intermediate-term applications advances the technology base needed to develop advanced applications. Many early nanotechnology enthusiasts were drawn from the computer industry because they perceived the possibility of a parallel course for nanotechnology development. However, the anemic growth we have witnessed in nanotechnology reminds me more of the biotech industry. When I was in the early phase of my career as a molecular biology researcher 35 years ago, the development of recombinant DNA technology inspired the hope that learning to produce in bacteria otherwise difficult or impossible to obtain molecules like interferons would launch a huge biotech industry that would rival the size and importance of the computer industry. Actual growth, while real, was much more modest because it turned out we had only scratched the surface of the necessary underlying science. The immune system was much more complicated than we realized, the genome was a vast, unexplored frontier, and the existence of such crucial phenomena as epigenetic regulation and RNA interference was unsuspected. Has the growth of the nanotechnology industry been slow because we are still as ignorant of nanoscience as we were of biology in 1976? Or is Skip Rung correct that government policies are at fault? There are clearly significant environmental, health, and safety issues with some nanomaterials that need to be managed so that we do not create a public relations nightmare for the fledgling nanotechnology industry. Can government provide necessary regulation without strangling innovation?

UCLA nanotech research mimics enzymes in directing chemical reactions

Good chemists are passive-aggressive — they manipulate molecules without actually touching them.

In a feat of manipulating substances at the nanoscale, UCLA researchers and colleagues demonstrated a method for isolating two molecules together on a substrate and controlling how those two molecules react when excited with ultraviolet light, making detailed observations both before and after the reaction. …

“This is one step in measuring and understanding the interactions between light and molecules, which we hope will eventually lead to more efficient conversion of sunlight to electrical and other usable forms of energy,” said lead study author Paul S. Weiss, a distinguished professor of chemistry and biochemistry who holds UCLA’s Fred Kavli Chair in Nanosystems Sciences. “Here, we used the energy from the light to induce a chemical reaction in a way that would not happen for molecules free to move in solution; they were held in place by their attachment to a surface and by the unreactive matrix of molecules around them.”

Weiss is also director of UCLA’s California NanoSystems Institute (CNSI) and a professor of materials science and engineering at the UCLA Henry Samueli School of Engineering and Applied Science.

Controlling exactly how molecules combine in order to study the resulting reactions is called regioselectivity. It is important because there are a variety of ways that molecules can combine, with varying chemical products. One way to direct a reaction is to isolate molecules and to hold them together to get regioselective reactions; this is the strategy used by enzymes in many biochemical reactions.

“The specialized scanning tunneling microscope used for these studies can also measure the absorption of light and charge separation in molecules designed for solar cells,” Weiss said. “This gives us a new way to optimize these molecules, in collaboration with synthetic chemists. This is what first brought us together with our collaborators at the University of Washington, led by Prof. Alex Jen.”

Alex K-Y. Jen holds the Boeing-Johnson Chair at the University of Washington, where he is a professor of materials science and engineering and of chemistry. The theoretical aspects of the study were led by Kendall Houk, a UCLA professor of chemistry and biochemistry who holds the Saul Winstein Chair in Organic Chemistry. Houk is a CNSI researcher.

The study’s first author, Moonhee Kim, a graduate student in Weiss’ lab, managed to isolate and control the reactions of pairs of molecules by creating nanostructures tailored to allow only two molecules fit in place. The molecules used in the study are photosensitive and are used in organic solar cells; similar techniques could be used to study a wide variety of molecules. Manipulating the way molecules in organic solar cells come together may also ultimately lead to greater efficiency.

To isolate the two molecules and align them in the desired — but unnatural — way, Kim utilized a concept similar to that of toddler’s toys that feature cutouts in which only certain shapes will fit.

She created a defect, or cutout, in a self-assembled monolayer, or SAM, a single layer of molecules on a flat surface — in this case, gold. The defect in the SAM was sized so that only two organic reactant molecules would fit and would only attach with the desired alignment. As a guide to attach the molecules to the SAM in the correct orientation, sulfur was attached to the bottoms of the molecules, as sulfur binds readily to gold.

“The standard procedure for this type of chemistry is to combine a bunch of molecules in solution and let them react together, but through random combinations, only 3 percent of molecules might react in this way,” UCLA’s Houk said. “Our method is much more targeted. Instead of doing one measurement on thousands of molecules, we are doing a range of measurements on just two molecules.”

After the molecules were isolated and trapped on the substrate, they still needed to be excited with light to react. In this case, the energy was supplied by ultraviolet light, which triggered the reaction. The researchers were able to verify the proper alignment and the reaction of the molecules using the special microscope developed by Kim and Weiss.

The research was published in Science (abstract). The figures and supporting material can be downloaded without a subscription.

The regioselectivity demonstrated in this research will probably not be precise enough or robust enough for diamond mechanosynthesis, but this is an elegant demonstration of the principle of positional control of chemical synthesis that will advance the underlying scientific understanding of how molecular interactions can be controlled and may also have near-term implications for improved solar cells.