Foresight Nanotech Institute Logo
Image of nano

Nanodot: the original nanotechnology weblog

Nanoscale box aids single-molecule optical detection

Posted by Stephanie C on July 29th, 2013

Credit: Jerome Wenger, Fresnel Institute

Good old fashioned boxes are here to stay, even in the context of nanoscale devices. Across a broad range of technologies and size regimes, boxes serve as containers for components, barriers against contaminants and/or radiation, and, as in the case of cell membranes, can be permeable to allow selected interactions between the interior and exterior. In a recent advance in optical detection, a nanoscale box-like housing was used to create an aperture that greatly enhanced the ability of antenna structures to detect single molecules at physiological concentrations. As reprinted at Phys.org:

Researchers at the Fresnel Institute in Marseille and ICFO-the Institute for Photonic Sciences in Barcelona report in Nature Nanotechnology the design and fabrication of the smallest optical device, capable of detecting and sensing individual biomolecules at concentrations that are similar to those found in the cellular context. The device called “antenna-in-a-box” consists of a tiny dimer antenna made out of two gold semi-spheres, separated from each other by a gap as small as 15nm. Light sent to this antenna is enormously amplified in the gap region where the actual detection of the biomolecule of interest occurs. Because amplification of the light is confined to the dimensions of the gap, only molecules present in this tiny region are detected. A second trick that the researchers used to make this device work was to embed the dimer antennas inside boxes also of nanometric dimensions. “The box screens out the unwanted “noise” of millions of other surrounding molecules, reducing the background and improving as a whole the detection of individual biomolecules.”, explains Jerome Wenger from Fresnel Institute. When tested under different sample concentrations, this novel antenna-in-box device allowed for 1100-fold fluorescence brightness enhancement together with detection volumes down to 58 zeptoliters (1 zL = 10-21L), i.e., the smallest observation volume in the world.

IFCO researcher and coauthor Maria Garcia-Parajo notes that the platform could also serve as a very bright, nanoscale light source.

Because the optical benefits come from the inner dimensions of the box (i.e. the aperture), the outer dimensions can vary, opening possibilities for customized sizes and shapes, as well as possible detection arrays.

-Posted by Stephanie C

DNA nanotechnology positions components to optimize single-molecule fluorescence

Posted by Jim Lewis on July 19th, 2013

Credit: Technische Universität Braunschweig

Recently we noted an extensive review of the use of DNA scaffolds to orient molecules for molecular studies, as this capability could lead to organizing functional components for atomically precise manufacturing (APM). An excellent example of this capability of DNA scaffolds, published last year in Science [abstract] has been made available for open access: “Fluorescence enhancement at docking sites of DNA-directed self-assembled nanoantennas” (pdf). A press release from the Technische Universität Braunschweig (in German, translated by http://translate.google.com/):

Light on the nanoscale focus: Researchers present tiny lenses from nanoparticles and DNA

Conventional lenses may focus light only to a volume of about one femtoliters (10-15 liters), which corresponds to a cubic micron. This limitation is a result of diffraction, which is inherent in all conventional lenses, and prevents many applications in the field of nanotechnology. The research group led by Prof. Philip Tinnefeld, Institute of Physical and Theoretical Chemistry, Technical University of Braunschweig, now has developed a method, are produced in parallel with the millions of so-called nano-lenses of metallic nanoparticles and DNA. These nano-lenses allow us to investigate even single molecules up to one hundred times more precise.

Read the rest of this entry »

Nanotechnology, optical lithography, and petabyte data storage media

Posted by Jim Lewis on July 16th, 2013

Credit: Nature Communications

Foresight’s interest is in advancing nanotechnology to the point of developing high-throughput atomically precise manufacturing, but it is worth noting occasionally the potential applications of nanoscale technologies that achieve less than atomic precision. These two examples point toward several-orders-of-magnitude improvement in data storage technology. A hat tip to Phys.org for reprinting this article written by researchers at Australia’s Swinburne University of Technology “More data storage? Here’s how to fit 1,000 terabytes on a DVD” by M Gu, Y Cao, and Z Gan:

In Nature Communications [open access article] today, we, along with Richard Evans from CSIRO, show how we developed a new technique to enable the data capacity of a single DVD to increase from 4.7 gigabytes up to one petabyte (1,000 terabytes). This is equivalent of 10.6 years of compressed high-definition video or 50,000 full high-definition movies. …

Read the rest of this entry »

Recent highlights and discussions of APM concepts

Posted by Stephanie C on July 12th, 2013

The release of Eric Drexler’s new book Radical Abundance has sparked a resurgence of discussion about nanotechnology and the global future.

Last month, Nanowerk reprinted Drexler’s blog write-up entitled The Physical Basis of High-Throughput Atomically Precise Manufacturing, a reader-friendly overview highlighting parallels between molecular manufacturing and conventional chemistry and manufacturing.

Over the last couple months, Robin Hanson, associate professor of economics at George Mason and a well-known name to many in the broader Foresight community, has been posting his critiques of various aspects of Radical Abundance, leading to some response and conversation that Drexler has featured on his blog site metamodern.com.
-Posted by Stephanie C

Reviews of DNA nanotechnology-atomically precise microscale objects

Posted by Jim Lewis on July 9th, 2013

Recently we noted the use of DNA nanotechnology to build a solar energy antenna as another example of progress in the modular molecular composite nanosystems (MMCNs) approach to developing atomically precise manufacturing. Structural DNA nanotechnology is currently the only way we have to manufacture large (million-atom, 100-nm-scale) arbitrarily complex atomically precise objects, so it plays a central role in the MMCN approach. Two very useful recent overviews of structural DNA nanotechnology have been made freely available on the web.

DNA nanotechnology: a curiosity or a promising technology? by Thomas Tørring and Kurt V. Gothelf, Center for DNA Nanotechnology (CDNA) at the Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Denmark, nicely covers the most important results of this extensive and rapidly progressing field in a very brief and accessible article.

A more detailed and technical review emphasizes the use of DNA scaffolds to orient molecules for single-molecule studies: “Single-Molecule Analysis Using DNA Origami” by Arivazhagan Rajendran, Masayuki Endo, and Hiroshi Sugiyama of Kyoto University and Japan Science and Technology Corporation [abstract] has been made available by the authors as a full-text PDF here. This extensive review covers single-molecule biomolecular recognition, conformational analysis, chemical reactions, enzymatic reactions, single molecule fluorescence studies, and cargo transporters and DNA robots. As documented by this review, the volume of work in this field has expanded to the point that we can cover only a small part of it here, so this review is a good place to get some appreciation of what is happening. The part that struck me as most relevant to atomically precise manufacturing was the example of “click chemistry” on a DNA origami surface (section 4.2, Fig. 7) since this might represent a path toward positional control of chemical synthesis.
—James Lewis, PhD

Foresight Advisor Doug Engelbart, 1925-2013, will be greatly missed

Posted by Jim Lewis on July 3rd, 2013

Douglas Engelbart in 2008

Douglas Engelbart in 2008

It is with great sadness that Foresight acknowledges the passing of Foresight Advisor Doug Engelbart, Ph.D. (1925-2013), a visionary technologist whose early inventions led to today’s Information Revolution. From his NY Times obituary “Douglas C. Engelbart, Inventor of the Computer Mouse, Dies at 88” by John Markoff:

Douglas C. Engelbart, a visionary scientist whose singular epiphany in 1950 about technology’s potential to expand human intelligence led to a host of inventions — among them the computer mouse — that became the basis for both the Internet and the modern personal computer, died on Tuesday at his home in Atherton, Calif. He was 88. …

Beginning in the 1950s, when computing was in its infancy, Dr. Engelbart set out to show that progress in science and engineering could be greatly accelerated if researchers, working in small groups, shared computing power. He called the approach “bootstrapping” and believed it would raise what he called their “collective IQ.” …

In a single stroke he had what might be called a complete vision of the information age. He saw himself sitting in front of a large computer screen full of different symbols, a vision most likely derived from his work on radar consoles while in the Navy after World War II. The screen, he thought, would serve as a display for a workstation that would organize all the information and communications for a given project.…

Dr. Engelbart was awarded the National Medal of Technology, the Lemelson-MIT Prize and the Turing Award, among others honors.…

Dr. Engelbart’s inventions were part of his long=term goal of “Boosting mankind’s capability for coping with complex, urgent problems“:

The Doug Engelbart Institute was founded by Doug Engelbart with daughter Christina Engelbart to further his lifelong career goal of boosting our collective capability to solve important problems intelligently, for which he coined the term Collective IQ.

We recognize that the opportunities, problems, and challenges we face – whether business, social, political, economic, environment – are increasing exponentially on a global scale, so finding exponentially more powerful ways to collectively address important challenges is critical;

This is both a dire threat and a golden opportunity – companies, initiatives, regions, nations that kick into gear on this soonest will likely surpass those that don’t in leaps and bounds.

The sooner we reach critical mass as a planet, the better off we all are, and thus there is tremendous value in sharing best practices, and in addressing this collectively as a Grand Challenge.

Dr. Engelbart served on Foresight’s Board of Advisors since 1997. He was particularly interested in assisting Foresight in our goal of speeding the positive impacts of new technologies while preventing negative uses, and joined us in advocating online hypertext-based discussion and argumentation systems for exploring and projecting coming technological applications. His vision and faith in the ability of human intelligence to master humanity’s exponentially growing problems will be sorely missed.
—James Lewis, PhD

DNA nanotechnology builds solar energy antenna

Posted by Jim Lewis on June 21st, 2013

(Credit: Image courtesy of Chalmers University of Technology)

The modular molecular composite nanosystems (MMCNs) approach to developing atomically precise manufacturing, described in the 2007 Technology Roadmap for Productive Nanosystems, proposes using DNA scaffolds to organize smaller functional components to execute complex tasks. In another demonstration of the functional utility of DNA scaffolds, scientists in Sweden have used DNA scaffolds to position dye molecules to increases the efficiency of artificial photosynthesis. A hat tip to ScienceDaily for reprinting this news release from Chalmers University of Technology “DNA constructs antenna for solar energy“:

A research team at Chalmers University of Technology has made a nanotechnological breakthrough in the first step required for artificial photosynthesis. The team has demonstrated that it is possible to use self-assembling DNA molecules as scaffolding to create artificial systems that collect light. The results were recently published in the esteemed scientific Journal of the American Chemical Society [abstract].

Scaffolding in plants and algae consists of a large number of proteins that organise chlorophyll molecules to ensure effective light collection. The system is complicated and would basically be impossible to construct artificially.

“It’s all over if a bond breaks,” says Jonas Hannestad, PhD of physical chemistry. “If DNA is used instead to organise the light-collecting molecules, the same precision is not achieved but a dynamic self-constructing system arises.”

With a system that builds itself, the researchers have begun to approach nature’s method. If any of the light-collecting molecules break, it will be replaced with another one a second later. In this sense, it is a self-repairing system as opposed to if molecules had been put there by researchers with synthetic organic chemistry.

Read the rest of this entry »

Mass production of higher quality oligonucleotides to spur DNA nanotechnology

Posted by Jim Lewis on June 6th, 2013

An illustration of the production of oligonucleotides. Credit: Björn Högberg

Currently structural DNA nanotechnology, either scaffolded DNA origami or DNA bricks, is the most promising method to build arbitrarily complex multi-million-atom atomically precise structures (see, for example these posts from the past six months Re-engineering a junction to give a new twist to DNA nanotechnology, Testing and improving scaffolded DNA origami for molecular nanotechnology, and Arbitrarily complex 3D DNA nanostructures built from DNA bricks). One of the major limitations of these methods, however, is the cost and quality of the small, single-stranded DNA molecules required, which are prepared by solid state chemical synthesis. Without these solid state synthesis methods, DNA nanotechnology, and indeed much of molecular biology, would have been impossible. However, chemical synthesis is expensive, rendering scale-up very difficult, and as the oligonucleotides become longer than a few tens of nucleotides, impurities and mistakes in synthesis become difficult to remove, potentially compromising atomic precision. Fortunately two DNA nanotechnology laboratories at the Karolinska Institute in Sweden and at Harvard and the Dana-Farber Cancer Institute appear to have solved this problem by harnessing biological molecular machine systems to make large quantities of very high quality single-stranded DNA oligonucleotides. A hat tip to KurzweilAI.net for reprinting the news from the Karolinska Institute “New method of mass-producing high-quality DNA molecules“:

The new method is versatile and able to solve problems that currently restrict the production of DNA fragments.

“We’ve used enzymatic production methods to create a system that not only improves the quality of the manufactured oligonucleotides but that also makes it possible to scale up production using bacteria in order to produce large amounts of DNA copies cheaply,” says co-developer Björn Högberg at the Swedish Medical Nanoscience Center, part of the Department of Neuroscience at Karolinska Institutet in Sweden.

The process of bioproduction, whereby bacteria are used to copy DNA sequences, enables the manufacture of large amounts of DNA copies at a low cost. Unlike current methods of synthesising oligonucleotides, where the number of errors increases with the length of the sequence, this new method according to the developers also works well for long oligonucleotides of several hundred nitrogenous bases.

Read the rest of this entry »

Quantum dot conduction impacted by stoichiometry, not dangling bonds

Posted by Stephanie C on May 29th, 2013

PbS quantum dot array. Credit: MIT

Quantum dots are semiconducting, nanoscale clusters that show electronic characteristics distinct from both bulk-scale materials and single molecules. Their special characteristics make quantum dots attractive for a broad range of potential applications, including photovoltaics and nanoscale transistors.

The size and shape of quantum dots impact electrical properties and can therefore be used to tune the dots (for example, for absorption/emission of desired wavelengths of light). In the case of photovoltaic cells, the performance of quantum dots has not lived up to theoretical potential, and it was expected that the reason had to do with the presence of dangling bonds at the dot surfaces. But new computational work from the lab of Jeffrey Grossman at MIT indicate that in the case of PbS quantum dots, the reason is stoichiometry. The work is published in Physical Review Letters (abstract) and is described in an article in Energy Harvesting Journal (selected excerpts shown):

In bulk quantities of lead sulfide, the material used for the quantum dots in this study, the ratio (known by chemists as “stoichiometry”) of lead atoms to sulfur atoms is exactly 1-to-1. But in the minuscule quantities of the material used to make quantum dots — which, in this case, were about 5 nanometers, or billionths of a meter, across — this ratio can vary significantly, a factor that had not previously been studied in detail. And, the researchers found, it turns out that this ratio is the key to determining the electrical properties of the material.

When the stoichiometry is a perfect 1-to-1, the quantum dots work best, providing the exact semiconductor behavior that theory predicts. But if the ratio is off in either direction — a bit more lead or a bit more sulfur — the behavior changes dramatically, impeding the solar cell’s ability to conduct charges.

Grossman explains that every atom inside the material has neighboring atoms on all sides, so all of that atom’s potential bonds are used, but some surface atoms don’t have neighbors, so their bonds can react with other atoms in the environment. These missing bonds, sometimes called “dangling bonds,” have been thought to play a critical role in a quantum dot’s electronic properties. As a result, the consensus in the field has been that the best devices will have what is known as full “passivation”: the addition of extra molecules that bind to any loose atomic bonds on the material’s surface. The idea was that adding more of the passivating material (called ligands) would always improve performance, but that didn’t work as scientists had expected: Sometimes it improved performance, but sometimes it made it worse.
Read the rest of this entry »

Germanane: germanium's answer to graphane

Posted by Stephanie C on May 15th, 2013

credit: Goldberger et al.

Soon after graphene sheets were being produced on a laboratory scale routinely, researchers began producing the hydrogenated version graphane (with a hydrogen atom on each carbon). This step is one of many approaches aimed at harnessing graphene’s powerful conductivity and is also being explored for hydrogen storage and other potential applications (more info in this 2009 ScienceDaily article From Graphene to Graphane…). Despite the divergence from planarity which naturally accompanies the shift from sp2 to sp3 hybridization, graphane is considered a 2D material.

Brought to our attention by Christine Peterson, a new addition to the family of 2D honeycomb-lattice materials has arrived: germanane. Structurally analogous to graphane, germanane comprises hydrogenated, hexagonally arranged germanium atoms in single (or few) layer sheets. Like silicane and silicene (see companion post Silicene: silicon’s answer to graphene), germanane should have a band gap, possibly allowing it to be implemented sooner than graphene.

While bulk germanium was semi-successfully used to make the first transistors, its low resistivity at higher temperatures and high production costs limited its practical use, and silicon soon became the semiconductor of choice. But going nanoscale may be a game changer, if the right combination of performance, cost, and ease of manufacture can be found.
Read the rest of this entry »

Drexler's book tour extends to U.S. May6-9

Posted by Stephanie C on May 4th, 2013

Recently we pointed at a Forbe’s interview with Eric Drexler, in anticipation of his pending new book Radical Abundance.

The book  has shipped, and Drexler’s tour schedule now includes a few stops on the coasts of the U.S:

New York: May 6th

Los Angeles: May 8th & 9th

Seattle: May 9th

Find exact times and locations on Drexler’s website, and find more information about the book from publisher Public Affairs and/or from your favorite book store.

If you’ve been imagining an updated version of Nanosystems, you’re in for a surprise. The book invites us to take a remarkable journey through the personal and educational experiences that led Drexler to contemplate the global future and to develop the foundations and concepts of atomically precise manufacturing, through a surprisingly accessible tour of the nanoscale world, and through a deeply thoughtful discussion of not only crucial realities of revolutionary new technology, but of crucial uncertainties as well.

-Posted by Stephanie C

Silicene: silicon's answer to graphene

Posted by Stephanie C on May 1st, 2013

Credit: Le Lay et al.

**July 2014 Update: New research suggests that silicene has never actually been successfully synthesized! See article on Phys.org**

On the list of potential post-silicon materials for electronics and chips is none other than silicon. More specifically, silicene — 2D sheets of hexagonally arranged silicon atoms, structurally analogous to graphene and experimentally characterized by physicist Guy Le Lay of Aix-Marseille University in France (2012 abstract here).

While graphene possesses exceptional performance qualities, it can’t be directly swapped in to existing silicon-based industry and technology. As described last year in the ExtremeTech article Silicene discovered: Single-layer silicon that could beat graphene to market:

Unlike silicon (or germanium)*, graphene doesn’t have a bandgap, which makes it very hard to actually build a switching device — such as a transistor — out of it. Researchers have had some luck in introducing a bandgap, but graphene is still a long way away from being used in current silicon processes.

Silicene … should be compatible with silicon-based electronics and the huge, existing semiconductor fabrication processes.

*Speaking of germanium, if you’re wondering whether it’s getting a piece of the action the answer is yes. See the companion post Germanane: germanium’s answer to graphane.

So, while the prospects of graphene-based devices are still tremendous, other materials that might allow more near-term integration into existing systems remain attractive.

But the honeycomb lattice may be silicene’s only resemblance to graphene. In the recent Nature news article Sticky Problem Snares Wonder Material, silicene is described as a “super sticky” material that “crinkles into bumps and ridges.” Before silicene’s theoretical properties can be experimentally tested, stable sheets of silicene need to be fabricated. A number of labs are working on it (find graphics and references in this pdf of a talk by Prof. Le Lay), and silicene is being included in more research programs under the graphene/honeycomb lattice umbrella.

What fascinates me most is the notion that a material on the nanoscale could replace its own bulk-scale counterpart for advanced, future applications – a great example of the wonder of the nanoscale. We may need to revise the term “post-silicon” to “post-bulk-silicon”.
-Posted by Stephanie C

A framework to promote critical thinking about nanotechnology

Posted by Jim Lewis on April 26th, 2013

Foresight's Director of Education Miguel F. Aznar

Last year we announced a talk that Miguel F. Aznar, Foresight’s Director of Education, would be givng a talk on critical thinking about nanotechnology. The talk “Critical Thinking about Nanotechnology” is now available on the web; however, only in Spanish. Here for comparison with the output from translate.Google.com, are the first two paragraphs from the English draft that Mr. Aznar forwarded:

Most people do not know what nanotechnology is, but they make choices that are influenced by nanotechnology. As individuals and as groups we make choices in education, career/employment, politics, health, energy, and environment that are influenced by nanotechnology because it is changing the tools that we use in an increasing number of fields. What does the general public need to know about nanotechnology in order to make informed, rational choices?

Nanotechnology presents several challenges. First, it crosses disciplines, so understanding a given example of it could require familiarity with, for example, physics and microbiology. Few experts span such diverse fields. Second, it requires experts. Designing a nanoscale enclosure to carry chemicals into a cell’s mitochondria requires expert understanding of chemistry and cell biology. Third, the field—or fields—of nanotechnology are expanding all the time. So a full understanding becomes ever less possible with global, around-the-clock experimentation and publication.

Read the rest of this entry »

Superparamagnetism-explicated-for us

Posted by Stephanie C on April 17th, 2013

Nickel nanocrystals mechanically coupled to a piezoelectric substrate allowed a magnetic field to be controlled by an electric field. Credit: Carman et al., UCLA

Even though the sound of it is something quite atrocious, superparamagnetism may become a familiar term in the context of nanoscale electronics and devices.

Loosely speaking, superparamagnetism is a size-based phenomenon in which materials that are ferromagnetic on the macroscale — meaning predisposed toward strong magnetization at room temperature, such as iron and nickel — display zero net magnetization at nanoparticle sizes. This phenomenon occurs because, at nanoparticle sizes, the energy required to disturb alignment of the material’s magnetic moment(s) decreases enough that ambient thermal energy is sufficient, and net magnetization gets zeroed out. The temperature required for thermal disruption of magnetization in bulk nickel is over 300 °C, but drops to about room temperature below 50-nm particle size (and continues to drop rapidly with decreasing particle size).

If you’re like me, your beanie is already spinning, but what does this have to do with nanoscale devices?

Much of technology as we know it utilizes natural electromagnetism: when a current runs through a wire, a weak magnetic field is produced. To maximize the magnetic field strength, a typical macroscale electromagnet is made by coiling a conducting wire around a ferromagnetic (usually iron) core. Controlling the electrical current through the wire then allows a very strong magnetic field to be turned on and off and tuned in magnitude.

The problem is, this configuration doesn’t work well at very small sizes primarily due to resistive loss (energy lost as heat). Further, bringing ferromagnetic core materials down to nanoparticle sizes means dealing with superparamagnetic behavior, a significant divergence from the macroscale.

Thus, the push for device miniaturization includes research into new approaches for electrically controlling magnetization on small (especially nano) size scales, at room temperature.
Read the rest of this entry »

Atomically precise placement of dangling bonds on silicon surface

Posted by Jim Lewis on April 5th, 2013

'Scanning tunnelling microscopy (STM) images of the quantum states of an artificial atomic defect structure in silicon. This structure was fabricated by using the STM to individually remove five hydrogen atoms from a hydrogen-terminated silicon (001) surface. The absence of the hydrogen atoms creates “dangling bond” states that interact to form extended, artificial molecular orbitals. Only the imaging bias voltage has been changed in the three images shown (from left to right, -1.4, +1.4, and +1.8 Volts).' (credit: London Centre for Nanotechnology)

We have previously speculated here whether the continued improvement of technology to place single atoms on silicon with atomic precision for the purpose of developing practical quantum computers would also lead to more general methods of atomically precise or molecular manufacturing. That speculation remains open, but we note that the field of atomically precise quantum engineering continues to advance. A hat tip to ScienceDaily for reprinting this University College London news release “Building quantum states with individual silicon atoms“:

By introducing individual silicon atom ‘defects’ using a scanning tunnelling microscope, scientists at the London Centre for Nanotechnology have coupled single atoms to form quantum states.

Published today in Nature Communications [open access paper: Quantum engineering at the silicon surface using dangling bonds], the study demonstrates the viability of engineering atomic-scale quantum states on the surface of silicon – an important step toward the fabrication of devices at the single-atom limit.

Advances in atomic physics now allow single ions to be brought together to form quantum coherent states. However, to build coupled atomic systems in large numbers, as required for applications such as quantum computing, it is highly desirable to develop the ability to construct coupled atomic systems in the solid state.

Read the rest of this entry »

RNA-protein motor for unidirectional movement of DNA in nanomachinery

Posted by Jim Lewis on April 1st, 2013

Credit: Zhengyi Zhao, University of Kentucky

One of nature’s many types of molecular motors combines protein and RNA subunits to force viral (in this case, bacteriophage) DNA into a protein capsid. The understanding of the molecular mechanism by which this motor works has been advanced by the discovery that it revolves the DNA around a central channel, as the Earth revolves around the sun, rather than by rotating, as the Earth does about it axis. A hat tip to ScienceDaily for pointing to this research. From a University of Kentucky news release “Guo lab discovers new class of revolution biomotor and solves mystery in viral DNA packaging:”

Scientists at the University of Kentucky have cracked a 35-year-old mystery about the workings of natural “biomotors.” These molecular machines are serving as models for development of synthetic nanomotors that will someday pump therapeutic DNA, RNA or drugs into individual diseased cells.

The report, revealing the innermost mechanisms of these motors in a bacteria-killing virus and a “new way to move DNA through cells,” is being published online today in the journal ACS Nano.

The article, “Mechanism of One-Way Traffic of Hexameric Phi29 DNA Packaging Motor with Four Electropositive Relaying Layers Facilitating Anti-Parallel Revolution,” can be downloaded with free, open access from http://pubs.acs.org/doi/abs/10.1021/nn4002775.

Peixuan Guo, director of the UK Nanobiotechnology Center, and his colleagues explain that two motors have been found in nature: A linear motor and a rotating motor. Now they report discovery of a third type, a revolving molecular motor.

Read the rest of this entry »

Nanotechnology revolution: An interview with Eric Drexler

Posted by Stephanie C on March 29th, 2013

In anticipation of Eric Drexler’s new book, Forbes contributor Bruce Dorminey interviews him about the meaning of nanotechnology and its revolutionary prospects. Selected excerpt:


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.

-Posted by Stephanie C

Re-engineering a junction to give a new twist to DNA nanotechnology

Posted by Jim Lewis on March 29th, 2013

Credit: Biodesign Institute

Of all of the paths toward molecular manufacturing, structural DNA nanotechnology seems to provide the most frequent and photogenic advances. By re-engineering the Holliday junction, the basic cross-over structure adapted to build complex structures from DNA, Prof. Hao Yan and his colleagues has been able to construct a variety of new wire frame and mesh structures. A hat tip to ScienceDaily for reprinting this Arizona State University news release “ASU scientists develop innovative twists to DNA nanotechnology“:

In a new discovery that represents a major step in solving a critical design challenge, Arizona State University Professor Hao Yan has led a research team to produce a wide variety of 2-D and 3-D structures that push the boundaries of the burgeoning field of DNA nanotechnology.

The field of DNA nanotechnology utilizes nature’s design rules and the chemical properties of DNA to self-assemble into an increasingly complex menagerie of molecules for biomedical and electronic applications. Some of the Yan lab’s accomplishments include building Trojan horse-like structures to improve drug delivery to cancerous cells, electrically conductive gold nanowires, single molecule sensors and programmable molecular robots.

With their bio-inspired architectural works, the group continues to explore the geometrical and physical limits of building at the molecular level.

Read the rest of this entry »

New advancement in 3D imaging of nanoparticles at atomic resolution

Posted by Stephanie C on March 28th, 2013

Graphic representation of a 3-D atomic resolution screw dislocation in a platinum nanoparticle. Credit: Chien-Chun Chen and I-Sheng Chou, UCLA

Researchers from UCLA’s California NanoSystems Institute and Northwestern University have combined multiple imaging techniques to produce high quality 3D images of platinum nanoparticles, allowing advanced visualization of atomic-scale structural defects (an important advancement over X-ray crystallography).

The original 2012 work, published in Nature and posted by Jim Lewis here, used electron tomography to study 10-nm gold particles and was described at Phys.org:


“This is the first experiment where we can directly see local structures in three dimensions at atomic-scale resolution — that’s never been done before,” said Jianwei (John) Miao, a professor of physics and astronomy and a researcher with the California NanoSystems Institute (CNSI) at UCLA.

X-ray crystallography is a powerful technique for revealing the structure of perfect crystals, which are materials with an unbroken honeycomb of perfectly spaced atoms lined up as neatly as books on a shelf. Yet most structures existing in nature are non-crystalline, with structures far less ordered than their crystalline counterparts — picture a rock concert mosh pit rather than soldiers on parade.

Miao and his colleagues used a scanning transmission electron microscope to sweep a narrow beam of high-energy electrons over a tiny gold particle only 10 nanometers in diameter (almost 1,000 times smaller than a red blood cell). The nanoparticle contained tens of thousands of individual gold atoms, each about a million times smaller than the width of a human hair. These atoms interact with the electrons passing through the sample, casting shadows that hold information about the nanoparticle’s interior structure onto a detector below the microscope.

Miao’s team discovered that by taking measurements at 69 different angles, they could combine the data gleaned from each individual shadow into a 3-D reconstruction of the interior of the nanoparticle. Using this method, which is known as electron tomography, Miao’s team was able to directly see individual atoms and how they were positioned inside the specific gold nanoparticle.

Read the rest of this entry »

Computationally designed peptide sneaks nanoparticles past immune system

Posted by Jim Lewis on March 15th, 2013

(credit: Mary Leonard, University of Pennsylvania Biomedical Art & Design)

Research into using nanotechnology for improved drug delivery continues to advance as current nanoparticle technology is combined with increasingly more sophisticated biotechnology. One major problem with using nanoparticles for targeted drug delivery is that the patient’s immune system often clears the particle before they can be effective. A new approach uses a peptide derived from an important immune system molecule to fool the immune system. A commentary accompanying the publication (abstract) of the research in Science describes how short peptides from a human protein called CD47, which tells important immune system cells that cells or particles bearing the protein are human, not foreign, were used as a “passport” to get nanoparticles past the immune system. Additional details are supplied in a University of Pennsylvania news release “Penn Researchers Develop Protein ‘Passport’ That Helps Nanoparticles Get Past Immune System“:

… The research was conducted by professor Dennis Discher, graduate students Pia Rodriguez, Takamasa Harada, David Christian and Richard K. Tsai and postdoctoral fellow Diego Pantano … “From your body’s perspective,” Rodriguez said, “an arrowhead a thousand years ago and a pacemaker today are treated the same — as a foreign invader.

“We’d really like things like pacemakers, sutures and drug-delivery vehicles to not cause an inflammatory response from the innate immune system.”

The innate immune system attacks foreign bodies in a general way. Unlike the learned response of the adaptive immune system, which includes the targeted antibodies that are formed after a vaccination, the innate immune system tries to destroy everything it doesn’t recognize as being part of the body.

This response has many cellular components, including macrophages — literally “big eaters” — that find, engulf and destroy invaders. Proteins in blood serum work in tandem with macrophages; they adhere to objects in the blood stream and draw macrophages’ attention. If the macrophage determines these proteins are stuck to a foreign invader, they will eat it or signal other macrophages to form a barrier around it.

Read the rest of this entry »