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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.

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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.

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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.

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A teenager’s step toward nanomedicine innovation

Posted by Stephanie C on March 6th, 2013

In this Forbes interview, contributor John Nosta introduces us to a teen worth watching: fifteen-year-old Jack Andraka, whose effort to design a nanotube-based sensor for pancreatic cancer detection was initially ignored. The interview taps into some aspects of how innovation occurs and the challenges of bringing new ideas to fruition – aspects which transcend age, education level, and field of study. In Jack’s words:


I like to read a lot of journals and articles about different topics and then lie on the couch or take a walk and just let all the information settle. Then all of a sudden I can get an idea and connect some dots. Then it’s back to reading so I can fill in missing pieces.

[I] found the names and professional emails of lots of professors in my area who were working on pancreatic cancer…. Week after week I’d receive endless rejections. The most helpful one was actually from a researcher who took the time to point out every flaw and reason why my project was impossible.

One of my most world- expanding experiences came very quickly when I went to Singularity U in California. I met people who weren’t afraid of failure, but just used failure to say well that path didn’t work and moved on.

Stories like this are good reminders to value not only good ideas, but to value people who show propensity for innovation.
-Posted by Stephanie C

Proposed Brain Activity Map may also advance nanotechnology

Posted by Jim Lewis on March 1st, 2013

(credit: Comp. Cog. Neurosci Lab/ Olaf Sporns, Indiana Univ.)

A proposal alluded to by President Obama in his State of the Union address to construct a dynamic “functional connectome” Brain Activity Map (BAM) would leverage current progress in neuroscience, synthetic biology, and nanotechnology to develop a map of each firing of every neuron in the human brain—a hundred billion neurons sampled on millisecond time scales. Although not the intended goal of this effort, a project on this scale, if it is funded, should also indirectly advance efforts to develop artificial intelligence and atomically precise manufacturing. In his blog, Robert L. Blum provides an excellent overview and brief introduction. From “BAM: Brain Activity Map: Every Spike from Every Neuron“:

A recent research proposal called BAM for Brain Activity Map Project generated much excitement. (The BAM proposal, published in Neuron in June 2012 is online, and an earlier draft with far greater detail is also online.)

(Addendum: 18 Feb 2013: I started drafting this story in Nov, 2012. Today it was headline news when it was made public that THIS is the very proposal that President Obama alluded to in his recent State of the Union address. See John Markoff’s NY Times piece. NIH is drafting a 3 billion dollar, 10 year proposal to fund this project. Also see this 25 Feb 2013 NY Times follow-up by Markoff.) …

The essence of the BAM proposal is to create the technology over the coming decade to be able to record every spike from every neuron in the brain of a behaving organism. While this notion seems insanely ambitious, coming from a group of top investigators, the paper deserves scrutiny. At minimum it shows what might be achieved in the future by the combination of nanotechnology and neuroscience. …

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Studying environmental impacts of nanoparticles using mesocosms

Posted by Stephanie C on February 28th, 2013

Mesocosms. Credit: Benjamin Coleman

The advent of new technologies is typically followed by new government regulation, and in the absence of data, fear-based reactionism can have far too much influence on policy. Quality research studies on real risks and impacts of nanoscale technologies can help lead to legitimate scientific consensus and appropriate regulation.

Engineered nanoparticles draw particular attention, because the same unique properties that give rise to special utility may also give rise to special health and environmental risks.

To calibrate our responses to nanoparticle toxicology studies, it is important to note whether an experiment reasonably represents likely exposure scenarios and whether nanoscale size is in fact a contributing factor to observed effects.

Recently highlighted at Phys.org, researchers at Duke University are investigating environmental impacts of widely used silver nanoparticles by way of experiments that seek to represent real-world exposure levels.

Previous studies have involved high concentrations of the nanoparticles in a laboratory setting, which the researchers point out, doesn’t represent “real-world” conditions.

For their studies, the researchers created mesocosms, which are small, man-made structures containing different plants and microorganisms meant to represent the environment. They applied sludge with low doses of silver nanoparticles in some of the mesocosms, then compared plants and microorganisms from treated and untreated mesocosms after 50 days.
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Nanotechnology delivers potent anti-cancer agent where it needs to go

Posted by Jim Lewis on February 22nd, 2013

(Credit: Courtesy of UCLA Engineering)

One of the most promising near-term applications of current nanotechnology is in targeted drug delivery to treat cancer. Despite the fact that a number of approaches based on very different areas of nanoscience have shown promise in delivering a wide variety of agents in different animal models of cancer, a number of challenges remain, principally involving the stability of the nanoparticles in the circulatory system, getting them into cancer cells, releasing the cargo to kill the cells, and the fact that cancer cells often have defenses against anti-cancer drugs. A core-shell nanoparticle has been cleverly adapted to deliver a particularly effective agent to where it is needed. A hat tip to ScienceDaily for reprinting this UCLA news release “Tiny capsule effectively kills cancer cells“:

Devising a method for more precise and less invasive treatment of cancer tumors, a team led by researchers from the UCLA Henry Samueli School of Engineering and Applied Science has developed a degradable nanoscale shell to carry proteins to cancer cells and stunt the growth of tumors without damaging healthy cells.

In a new study, published online Feb. 1 in the peer-reviewed journal Nano Today [abstract], a group led by Yi Tang, a professor of chemical and biomolecular engineering and a member of the California NanoSystems Institute at UCLA, reports developing tiny shells composed of a water-soluble polymer that safely deliver a protein complex to the nucleus of cancer cells to induce their death. The shells, which at about 100 nanometers are roughly half the size of the smallest bacterium, degrade harmlessly in non-cancerous cells.

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Christine Peterson on pushing the future in a positive direction

Posted by Jim Lewis on February 20th, 2013

Christine Peterson

Foresight Co-Founder and Past President Christine Peterson is interviewed on the Singularity Weblog in a 47-minute tour that covers nanotechnology, the founding of the Foresight Institute, her work on personal life extension through Health Activator, open source, and the Technological Singularity. “Christine Peterson on Singularity 1 on 1: Join Us to Push the Future in a Positive Direction“:

During my Singularity 1 on 1 interview with Christine Peterson we discuss a variety of topics such as: how she got interested in nanotechnology and the definition thereof; how, together with Eric Drexler, she started the Foresight Institute for Nanotechnology; her interest in life extension; Dr. Drexler’s seminal book Engines of Creation; cryonics and chemical brain preservation; 23andMe and other high- and low-tech tips for improved longevity; whether we should fear nanotechnology or not; the 3 most exciting promises of nanotech; women in technology; coining the term “open source” and using Apple computers; the technological singularity and her take on it…

Hear Christine discuss some challenges while presenting an essentially optimistic message—a wonderful future is coming from science and technology over the next few decades—a future that encourages everyone to get involved.
—James Lewis, PhD

Christine Peterson interviewed on nanotechnology

Posted by Jim Lewis on February 12th, 2013

An interview with Foresight Co-Founder and Past President Christine Peterson was filmed by Adam Ford in conjunction with the Humanity+ conference in San Francisco and is now available on YouTube. The interview is (surprise!) about nanotechnology, and the topics range from exciting medical applications to come in the next ten years from current nanoparticle technology to longer term efforts to develop smart objects, from utility fog to medical nanorobots. Other topics include near-term health and environmental issues with some nanoparticle technology, long term political issues after advanced nanotechnology is developed, the role of software, and, most of all, what we stand to gain when we learn to extend control of our manufacturing technology to atomic precision.
—James Lewis, PhD

Toward molecular fabrication: formation of distinct bond types by STM

Posted by Stephanie C on February 8th, 2013

Scanning probe manipulation of individual atoms and small molecules were amongst the early laboratory successes that helped bring broad scale attention to the feasibility and potential of nanoscale technologies, especially molecular fabrication.

Basic manipulations of atoms and bonds by scanning probe have become familiar capabilities that follow similar protocols: the STM tip is precisely positioned relative to the molecule and then energy (tunneling current) is modulated to achieve particular operations, including scanning, translocation across the substrate surface, and making/breaking chemical bonds.  Going a tremendous step beyond the basics, Wilson Ho* of University of California, Irvine and colleagues recently reported the selective formation of two distinct types of chemical bonds between gold adatoms and the sulfurs of 1,4-bis(4’-(acetylthio)styryl)benzene molecules (converting Ac-S-DSB-S-Ac to Au-S-DSB-S-Au) on a NiAl(110) surface.

1,4-bis(4’-(acetylthio)styryl)benzene

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Synthetic biology industrial revolution inspires hope for molecular manufacturing

Posted by Jim Lewis on February 2nd, 2013

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:

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Artificial molecular machine synthesizes a small peptide

Posted by Jim Lewis on January 28th, 2013

(Credit: Miriam Wilson)

Nature has evolved a partial system of molecular manufacturing. Although not capable of making arbitrarily complex, atomically precise structures that faithfully represent the immense diversity of chemically feasible structures, biology very early on evolved a method of assembling a wide range of molecular machines by linking particular types of subunit molecules together in a defined sequence. The structure that makes the most complex biological molecular machines is the ribosome, a complex of two subunits 20 to 30 nm in diameter and comprising several dozen RNA and protein molecules, which works with hundreds of other RNA and protein molecules to link amino acids together as specified by genetic information to make specific protein molecules. Scientists in the UK have succeeded in mimicking this basic process using a simple artificial molecular machine bearing no resemblance to the ribosome and an order of magnitude smaller in linear dimension than the ribosome. A hat tip to Phys.org for reprinting this University of Manchester news release “Molecular machine could hold key to more efficient manufacturing“:

An industrial revolution on a minute scale is taking place in laboratories at The University of Manchester with the development of a highly complex machine that mimics how molecules are made in nature.

The artificial molecular machine developed by Professor David Leigh FRS and his team in the School of Chemistry is the most advanced molecular machine of its type in the world. Its development has been published in the journal Science [abstract].

Professor Leigh explains: “The development of this machine which uses molecules to make molecules in a synthetic process is similar to the robotic assembly line in car plants. Such machines could ultimately lead to the process of making molecules becoming much more efficient and cost effective. This will benefit all sorts of manufacturing areas as many manmade products begin at a molecular level. For example, we’re currently modifying our machine to make drugs such as penicillin.” …

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Controlled stepwise rotation on a single atom bearing

Posted by Jim Lewis on January 21st, 2013

This illustration shows the structure of the molecular motors. (Credit: Saw-Wai Hla)

It is difficult to imagine any design for a mature molecular manufacturing system that does not require molecular motors. Now, as part of a plan to build more complex automated molecular machines, an international team has designed and built a molecular motor powered by electrons from a scanning tunneling microscope tip that uses a single atom as a bearing. A hat tip to KurzweilAI.net for reprinting this Ohio University news release “Scientists design, control movements of molecular motor“:

An international team of scientists has taken the next step in creating nanoscale machines by designing a multi-component molecular motor that can be moved clockwise and counterclockwise.

Although researchers can rotate or switch individual molecules on and off, the new study is the first to create a stand-alone molecular motor that has multiple parts, said Saw-Wai Hla, an Ohio University professor of physics and astronomy who led the study with Christian Joachim of A*Star in Singapore and CEMES/CNRS in France and Gwenael Rapenne of CEMES/CNRS.

It’s an essential step in creating nanoscale devices—quantum machines that operate on different laws of physics than classical machines—that scientists envision could be used for everything from powering quantum computers to sweeping away blood clots in arteries.

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Nanometer-scale optical positioning and focusing

Posted by Jim Lewis on January 16th, 2013

One of the core concepts of molecular manufacturing is that nanotechnology will evolve to the point that it will become possible to position small groups of reactive atoms at atomically precise desired locations on a work piece in order to build arbitrarily complex atomically precise structures. For several decades optical tweezers have been used to trap and manipulate micrometer-size objects, like bacteria, molecules attached to micrometer size beads, and organelles within eukaryotic cells. They have been limited in precision by the wavelength of light (about 400 to 700 nm) so that they have been unable to manipulate nanometer-scale objects. Two recently published papers raise the possibility that this technology might evolve through the use of surface plasmon polaritons to enable atomically precise positioning. One paper presents a theoretical proposal for extending optical trapping to particles smaller than 2 nm. The second presents an experimental demonstration of highly efficient nanofocusing.

The new aperture design (left) with two layers of silver separated by another of silicon dioxide. The structure focuses light in a novel way to trap particles smaller than ever before. The focused beams are shown in the illustration on the right. Credit: Amr Saleh

A hat tip to Phys.org for reprinting this Stanford Engineering news release by Kelly Servick “New Optical Tweezers Trap Specimens Just A Few Nanometers Across“:

To grasp and move microscopic objects, such as bacteria and the components of living cells, scientists can harness the power of concentrated light to manipulate them without ever physically touching them.

Now, doctoral student Amr Saleh and Assistant Professor Jennifer Dionne, researchers at the Stanford School of Engineering, have designed an innovative light aperture that allows them to optically trap smaller objects than ever before – potentially just a few atoms in size.

The process of optical trapping – or optical tweezing, as it is often known – involves sculpting a beam of light into a narrow point that produces a strong electromagnetic field. The beam attracts tiny objects and traps them in place, just like a pair of tweezers.

Unfortunately, there are natural limits to the technique. The process breaks down for objects significantly smaller than the wavelength of light. Therefore, optical tweezers cannot grasp super-small objects like individual proteins, which are only a couple of nanometers in diameter.

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$100,000 grants for 20 entrepreneurs under 20 years to develop their dreams

Posted by Jim Lewis on December 20th, 2012

Think about the smartest teenager (under 20) you know. Is this person passionate about science, technology, or entrepreneurship? If so, talk to him or her about starting a business or developing an invention or breakthrough. The 20 under 20 Thiel Fellowship offers $100,000 grants and lots of advice to smart innovators who are ready to pursue their dreams. It costs nothing to apply, and the deadline is December 31.

thielfellowship.org

http://www.nytimes.com/2012/09/16/business/the-thiel-fellows-forgoing-college-to-pursue-dreams.html

http://www.hulu.com/20-under-20-transforming-tomorrow

Testing and improving scaffolded DNA origami for molecular nanotechnology

Posted by Jim Lewis on December 19th, 2012

This 3-D print shows a DNA-based structure designed to test a critical assumption -- that such objects could be realized, as designed, with subnanometer precision. This object is a relatively large, three-dimensional DNA-based structure, asymmetrical to help determine the orientation, and incorporating distinctive design motifs. Subnanometer-resolution imaging with low-temperature electron microscopy enabled researchers to map the object -- which comprises more than 460,000 atoms -- with subnanometer-scale detail. (Credit: Dietz Lab, TU Muenchen)

Before this year the best way to build complex 3D nanostructures from DNA was to use scaffolded DNA origami (see, for example, this post). Last May scientists at the Wyss Institute introduced a DNA tile method for fabricating complex DNA objects that was much faster and much less expensive, and just two weeks ago we posted news that they had extended this method to make arbitrarily complex 3D DNA nanostructures from DNA bricks. Now scientists at the Technische Universität München have published two papers documenting major enhancements to scaffolded DNA origami. From “Reality check for DNA nanotechnology“:

Two major barriers to the advancement of DNA nanotechnology beyond the research lab have been knocked down. This emerging technology employs DNA as a programmable building material for self-assembled, nanometer-scale structures. Many practical applications have been envisioned, and researchers recently demonstrated a synthetic membrane channel made from DNA. Until now, however, design processes were hobbled by a lack of structural feedback. Assembly was slow and often of poor quality. Now researchers led by Prof. Hendrik Dietz of the Technische Universitaet Muenchen (TUM) have removed these obstacles.

One barrier holding the field back was an unproven assumption. Researchers were able to design a wide variety of discrete objects and specify exactly how DNA strands should zip together and fold into the desired shapes. They could show that the resulting nanostructures closely matched the designs. Still lacking, though, was the validation of the assumed subnanometer-scale precise positional control. This has been confirmed for the first time through analysis of a test object designed specifically for the purpose. A technical breakthrough based on advances in fundamental understanding, this demonstration has provided a crucial reality check for DNA nanotechnology.

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Two types of artificial muscle from nanotechnology

Posted by Jim Lewis on December 13th, 2012

The principle of contraction and extension of a telescopic polymer chain based on the supramolecular association of thousands of nano-machines. (Credit: Wiley-VCH Verlag GmbH & Co.KGaA. and CNRS)

Biology uses various types of molecular machines to produce movement, all of which are candidates to be mimicked for use in nanotechnology. Muscles produce movement through the contraction of systems of polymers, powered by the release of chemical energy. Now scientists from France’s CNRS have developed an artificial muscle that produces micrometer-scale movement through the coordinated action of thousands of individual molecular machines each producing nanometer-scale movement. A hat tip to Gene Ostrovsky at MedGadget for a story on this CNRS press release “Assembly of nano-machines mimics human muscle“:

For the first time, an assembly of thousands of nano-machines capable of producing a coordinated contraction movement extending up to around ten micrometers, like the movements of muscular fibers, has been synthesized by a CNRS team from the Institut Charles Sadron. This innovative work, headed by Nicolas Giuseppone, professor at the Université de Strasbourg, and involving researchers from the Laboratoire de Matière et Systèmes Complexes (CNRS/Université Paris Diderot), provides an experimental validation of a biomimetic approach that has been conceptualized for some years in the field of nanosciences. This discovery opens up perspectives for a multitude of applications in robotics, in nanotechnology for the storage of information, in the medical field for the synthesis of artificial muscles or in the design of other materials incorporating nano-machines (endowed with novel mechanical properties). This work has been published in the on-line version of the journal Angewandte Chemie International Edition [abstract].

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Optimal bond loads in designing molecular machines

Posted by Jim Lewis on December 11th, 2012

One issue in designing molecular machine systems to do nanoscale work, such as molecular manufacturing, is how to transfer energy to implement guided molecular motions, to move components or to make or break chemical bonds. In Chemistry World Philip Ball comments on recent research that provides fresh insights into how this process is optimized in biology, and which could prove useful in designing artificial molecular machine systems. From “Make or break: the laws of motion“:

… the question biology has to face is: what is the optimal bond strength for a given mechanical function? This issue is tackled by Henry Hess of Columbia University, US, in a paper that is stimulating fresh thinking about molecular machines [abstract]. Consider a kinesin motor protein ‘walking’ along a tubulin track. The objective is to transfer impulse from the protein’s motor stroke – a conformational change driven by hydrolysis of adenosine triphospate – to the protein–tubule interface, propelling the molecule forward. Hess compares it to a car (kinesin) stuck in mud (tubulin). Anyone who has ever faced this situation knows how delicately the coupling must be managed, by engaging the clutch to just the right degree. Too much and the wheel just spins: the bond snaps. Too little, and the wheel’s coupling to the engine is insufficient to generate movement. The optimal point is found where the wheel–mud adhesion is just about to cease.

… Hess shows that as the load on a bond is increased, the transfer of impulse across the bond has a peak. The position of this peak depends on the distance to the transition state for bond rupture along the reaction coordinate. In other words, here is a design criterion for the ideal molecular machine that transfers energy during reversible binding: the bond should be just strong enough to be likely to survive during the power stroke. …

Proposals of how to advance from current nanotechnology to atomically precise manufacturing (see, for example, the Technology Roadmap for Productive Nanosystems) embody a range of proposals for different stages of development, from biological molecular machines based on networks of weak noncovalent bonds, to nanoscale versions of macroscopic machines constructed from hard materials like diamond comprising dense networks of strong covalent bonds. An important question to be clarified is how (or if) the design rules for molecular machine systems change at various points along this continuum.
—James Lewis, PhD

Arbitrarily complex 3D DNA nanostructures built from DNA bricks

Posted by Jim Lewis on December 6th, 2012

Computer-generated 3D models (top) and corresponding 2D projection microscopy images (bottom) of nanostructures self-assembled from synthetic DNA strands called DNA bricks. (Image Credit: Yonggang Ke, Wyss Institute, Harvard University.)

This past May we posted news of a major advance in the toolkit for DNA nanotechnology. Researchers led by Wyss Institute core faculty member Peng Yin developed a very versatile, rapid, and inexpensive way to assemble arbitrarily complex 150-nm two-dimensional DNA nanostructures from 42-nucleotide DNA tiles. A hat tip to ScienceDaily for reprinting this Wyss Institute news release of another major advance from the same research group aided by another Wyss Core Faculty member William Shih “Researchers Create Versatile 3D Nanostructures Using DNA ‘Bricks’”:

Researchers at the Wyss Institute for Biologically Inspired Engineering at Harvard University have created more than 100 three-dimensional (3D) nanostructures using DNA building blocks that function like Lego® bricks — a major advance from the two-dimensional (2D) structures the same team built a few months ago.

In effect, the advance means researchers just went from being able to build a flat wall of Legos®, to building a house. The new method, featured as a cover research article in the 30 November issue of Science [abstract], is the next step toward using DNA nanotechnologies for more sophisticated applications than ever possible before, such as “smart” medical devices that target drugs selectively to disease sites, programmable imaging probes, templates for precisely arranging inorganic materials in the manufacturing of next generation computer circuits, and more. …

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