Nanodot: the original nanotechnology weblog

DNA nanotech continues to improve the devices it produces as Oxford University scientists fix several shortcomings seen in earlier versions of bipedal DNA molecular walkers that had been produced by several laboratories. A succinct summary of the improvements in the new DNA nanobot is given by Jessica Griggs at NewScientist.com. From “Nanobot lets DNA legs do the walking“:

A TWO-legged molecular machine that can walk unaided along a single strand of DNA could one day shift cargo around nanofactories. That’s the promise of a walking molecular nanobot made by researchers at the University of Oxford.

Molecular engines that walk along strands of DNA are nothing new, but none has featured as many successful features as the Oxford team’s device. Unlike earlier attempts, their nanobot doesn’t wander aimlessly back and forth, fall off its track or destroy its track as it walks. The team have also devised an ingenious way of powering the nanobot that allows it to move freely. Read the rest of this entry »

Nanotech could make possible the controlled release within the patient of up to four different drugs by irradiation with different wavelengths of near-infrared radiation. Near-IR light passes through human flesh to release drugs within the body. In a proof-of-concept experiment, two different DNA oligonucleotides were loaded on gold nanorods of two different shapes. Because the two different shaped-nanorods have different surface plasmon resonance peaks, radiation of an IR laser of 800-nm wavelength melted one type of nanorod and released one type of DNA oligonucleotide, while irradiation with a 1100-nm laser melted the other type and released the other DNA nucleotide. The released oligonucleotides were still functional. From MIT News Office, written by Anne Trafton “Gold particles deliver more than just glitter, Nanoparticles could carry drugs to treat cancer, other diseases“

Using tiny gold particles and infrared light, MIT researchers have developed a drug-delivery system that allows multiple drugs to be released in a controlled fashion.

Such a system could one day be used to provide more control when battling diseases commonly treated with more than one drug, according to the researchers.

“With a lot of diseases, especially cancer and AIDS, you get a synergistic effect with more than one drug,” said Kimberly Hamad-Schifferli, assistant professor of biological and mechanical engineering and senior author of a paper on the work that recently appeared in the journal ACS Nano [abstract]. Read the rest of this entry »

The answers of 151 thinkers and visionaries to the Edge Annual question for 2009 have been posted. The question: “WHAT WILL CHANGE EVERYTHING?” As phrased by John Brockman, Editor and Publisher, “What game-changing scientific ideas and developments do you expect to live to see?” In his answer, nanotechnology pioneer Eric Drexler points to a role for the imperative of sequestering carbon to ameliorate climate change in pushing the development of molecular manufacturing. In “Knowledge Spreading” he argues that everything will be changed by spreading knowledge of two scientific facts—first, that carbon stays in the atmosphere a long time, and second, that physics says we can develop new methods of manufacturing with which “we could make the products that would replace the infrastructure that is causing the accelerating and seemingly irreversible problem of climate change.”

Drexler continues:

What sorts of products? Returning to power generation, transportation, and manufacturing, picture roads resurfaced with solar cells (a tough, black film), cars that run on recyclable fuel (sleek, light, and efficient), and car-factories that fit in a garage. We could make these easily, in quantity, if we were good at making things.

Developing the required molecular manufacturing capabilities will require hard but rewarding work on a global scale, converting scientific knowledge into engineering practice to make tools that we can use to make better tools. The aim that physics suggests is a factory technology with machines that assemble large products from parts made of smaller parts (made of smaller parts, and so on) with molecules as the smallest parts, and the smallest machines only a hundred times their size. Read the rest of this entry »

Combining the novel electronic, magnetic, and optical properties of either semiconductor or metallic nanoparticles with the molecular recognition properties of DNA strands, nanotech has used DNA strands to assemble gold and other nanoparticles into distinct 1-dimensional or 2-dimensional structures, or into periodic 3-dimensional crystals (see this post from last year). Complementing these capabilities, structural DNA has provided complex structures from designed, branched DNA molecules, including DNA tiles that can be programmed to assemble into various two-dimensional arrays. Sometimes these arrays have been observed to curl into DNA nanotubes, probably due to difficult-to-predict steric effects. Now researchers have been able to attach gold nanoparticles to DNA tiles and, by varying the size of the nanoparticles and the presence of DNA stem loops on some tiles, have been able to control the formation from the DNA tiles of various three dimensional DNA nanotubes in which the gold nanoparticles form stacked rings, single spirals, double spirals, or nested spirals along the length of the DNA nanotube. From Arizona State University, via AAAS EurekAlert “The gold standard: Biodesign Institute researchers use nanoparticles to make 3-D DNA nanotubes“:

Arizona State University researchers Hao Yan and Yan Liu imagine and assemble intricate structures on a scale almost unfathomably small. Their medium is the double-helical DNA molecule, a versatile building material offering near limitless construction potential. Read the rest of this entry »

Molecular motors for early nanotech applications may be modeled on the various molecular motors found in biology. Using protein crystallography and electron microscopy, scientists have now revealed the working mechanism of one of the most powerful molecular motors known to biology. When viruses package their genomes into viral capsids, they must generate enormous forces (about 60 picoNewtons) to collapse the DNA double helix to crystalline atomic densities against the repulsion of the negatively-charged phosphates in the DNA stands. These studies show that the energy released by the hydrolysis of a molecule of ATP generates enough electrostatic force to alter the spatial relationship between two domains of the DNA packing motor protein (gp17) by 0.7 nm, equivalent to the vertical distance spanned by two base pairs of the DNA double helix. Consequently, a ring of composed by five molecules of gp17, acting in sequence, advances the DNA into the viral capsid by ten base pairs, or one turn of the helix. From Purdue University, “Biologists learn structure, mechanism of powerful ‘molecular motor’ in virus“:

Researchers have discovered the atomic structure of a powerful “molecular motor” that packages DNA into the head segment of some viruses during their assembly, an essential step in their ability to multiply and infect new host organisms.

The researchers, from Purdue University and The Catholic University of America, also have proposed a mechanism for how the motor works. Parts of the motor move in sequence like the pistons in a car’s engine, progressively drawing the genetic material into the virus’s head, or capsid, said Michael Rossmann, Purdue’s Hanley Distinguished Professor of Biological Sciences. Read the rest of this entry »

Nanotech may provide a way to “bypass” faulty brain wiring. Research on the interactions between carbon nanotubes and neurons shows that electrical phenomena in nanotubes can be linked to neuronal excitability and may lead to engineering interactions between nanomaterials and neurons. News from EPFL (Ecole Polytechnique Fédérale de Lausanne) “New’smart’ materials for the brain“:

Research done by scientists in Italy and Switzerland has shown that carbon nanotubes may be the ideal “smart” brain material. Their results, published December 21 in the advance online edition of the journal Nature Nanotechnology [abstract], are a promising step forward in the search to find ways to “bypass” faulty brain wiring.

The research shows that carbon nanotubes, which, like neurons, are highly electrically conductive, form extremely tight contacts with neuronal cell membranes. Unlike the metal electrodes that are currently used in research and clinical applications, the nanotubes can create shortcuts between the distal and proximal compartments of the neuron, resulting in enhanced neuronal excitability. Read the rest of this entry »

Christian Joachim (who shared the Foresight Nanotech Institute Feynman Prize in the Experimental category in 1997 and won in the Theoretical category in 2005) is heading a group of researchers working to bring about atomic-scale computing. ScienceDaily led us to this European Commission ICT Results feature “Computing in a molecule“, which describes their on-going efforts:

Over the last 60 years, ever-smaller generations of transistors have driven exponential growth in computing power. Could molecules, each turned into miniscule computer components, trigger even greater growth in computing over the next 60?

Atomic-scale computing, in which computer processes are carried out in a single molecule or using a surface atomic-scale circuit, holds vast promise for the microelectronics industry. It allows computers to continue to increase in processing power through the development of components in the nano- and pico scale. In theory, atomic-scale computing could put computers more powerful than today’s supercomputers in everyone’s pocket.

“Atomic-scale computing researchers today are in much the same position as transistor inventors were before 1947. No one knows where this will lead,” says Christian Joachim of the French National Scientific Research Centre’s (CNRS) Centre for Material Elaboration & Structural Studies (CEMES) in Toulouse, France. Read the rest of this entry »

Even very simple forms of nanotech can be surprisingly useful. Polishing teeth with silica nanoparticles produces much smoother surfaces than does polishing with larger silica particles, making it easier to remove harmful bacteria. From ScienceDaily “New tooth cavity protection: nanoparticles make surface too slippery for bacteria to adhere“:

Clarkson University Center for Advanced Materials Processing Professor Igor Sokolov and graduate student Ravi M. Gaikwad have discovered a new method of protecting teeth from cavities by ultrafine polishing with silica nanoparticles.

The researchers adopted polishing technology used in the semiconductor industry (chemical mechanical planarization) to polish the surface of human teeth down to nanoscale roughness. Roughness left on the tooth after the polishing is just a few nanometers, which is one-billionth of a meter or about 100,000 times smaller than a grain of sand.

Sokolov and Gaikwad showed that teeth polished in this way become too “slippery” for the “bad” bacteria that is responsible for the destruction of dental enamel. As a result the bacteria can be removed fairly easily before they cause damage to the enamel.

The research was published in the Journal of Dental Research (abstract).
—Jim

One of the main reasons that we are confident in the overall predictions of molecular manufacturing is that there are many pathways to it from current technology and using currently understood science. It is thus something of a milestone that we have arrived at a fork in the road about which there is room for disagreement about which path to take. The point at issue is diamondoid mechanosynthesis (DMS).

Eric Drexler has posted an essay in which he points out that he favors a pathway that leverages the capabilities of biochemistry and solution chemistry. He notes that he has always considered diamondoid mechanosynthesis a hard problem and a capability for advanced nanotech, not an early pathway.

Robert Freitas and Ralph Merkle are championing the direct DMS route. To extend the roadmap analogy, one could say that the solution-chemistry path is the long, winding river road and the DMS approach is the shortcut through the treacherous mountain passes.

Which is right? My own opinion is that this is the wrong question. There are many paths to productive nanosystems, and trying all of them is none too big an investment in our future. In the meantime, the more of a debate that develops between alternatives, the more the technical issues will be discussed and the more hitherto un-thought-of alternative pathways will be explored.

The first stage of the public conversation about a new technology, the debate is over whether heavier-than-air machines can fly. In the second stage, it’s over things like biplanes vs monoplanes.

Welcome to the second stage.

(Hat-tip to Next Big Future)

If you have a proposal on how nanotech could address a critical national and societal need, the National Institute of Standards and Technology (NIST) wants to hear from you. Nanowerk News reports “NIST seeks white papers on critical national needs, including nanotechnology“. From the source NIST announcement:

The National Institute of Standards and Technology (NIST) is interested in detailed pitches for critical national and societal needs that could be the basis for new competitions for research funding under its Technology Innovation Program (TIP).

In a Federal Register notice posted on Dec. 16, NIST asked interested parties to submit “white papers” describing an area of critical national need and the associated societal challenge and explain how those needs might be addressed through potential technological developments that fit the TIP profile of high-risk, high-reward R&D. The white papers, along with the input from NIST, the TIP Advisory Board, other government agencies, the technical communities and other stakeholders, will be incorporated into the TIP competition planning process.

Among the areas NIST lists as of particular interest, the following three seem especially suited for nanotech approaches:

• Energy—technologies that address emerging alternative energy sources;
• Water—technologies that address growing needs for fresh water supplies and ensure the safety of water and food supplies from contamination;
• Nanomaterials and nanotechnology—for example technologies that enable the scale-up of nanomaterials and nanodevices from lab prototypes to commercial manufacturing;

—Jim

Nanowerk News reports that an international nanotech collaboration of American and Korean scientists, funded by the Korean government, has developed multifunctional gold-coated nanowires that are designed to swim through the blood stream and attach to cancerous cells via antibodies against the cancer cells. Exposure to an electromagnetic field should heat the nanowires and destroy the cancerous cells while sparing nearby normal cells. Unfortunately, the University of Idaho press release on which the story is based is light on technical details:

The next big thing in cancer treatment may be hotter, covered in more gold, and even be a better swimmer than recent Olympic champion Michael Phelps.

Scientists at the University of Idaho are engineering multifunctional and dynamic nanowires coated in gold that swim through the bloodstream and attach to specific cancerous cells. Once there, an electromagnetic field heats the nanowires, which destroys the targeted cells. The research is supported by a new $425,000 grant, part of a multimillion dollar project funded by the Korean government as part of the International Global Collaboration Pioneer Program.

“Cancer is a dangerous enemy because radiation and chemical treatments cause a lot of side effects,” said Daniel Choi, associate professor of materials science and engineering at the University of Idaho and leader of the project. “We can’t avoid side effects 100 percent, but these nanowires will minimize the damage to healthy cells.” Read the rest of this entry »

A new nanotech method of DNA sequencing is 30,000 times faster than current DNA sequencing methods. The method, developed by a team at Pacific BioSciences in Menlo Park, California, uses a nanostructured array of thousands of waveguides—tiny hollow metal cylinders, each holding about a zeptoliter (10^-21 liter)—to isolate a single molecule of DNA and a single molecule of DNA polymerase. Each of the four nucleotide bases is labeled with a different colored fluorescent label, with the fluorescent dye attached to the portion of the nucleotide that is cleaved and removed after the nucleotide is added to the growing DNA chain. As each nucleotide base is incorporated into the growing DNA chain within one waveguide, a spot of light of the corresponding color first appears, and then disappears. The sequence of flashes in each well reveals the DNA sequence copied in that well in real time. The array allows the simultaneous observation of thousands of single molecule DNA sequencing reactions. Preliminary experiments published in Science (abstract) report 100% accuracy with test DNA templates 150 bases in length. For more Read the rest of this entry »

The following is an edited and revised version of the talk I gave at the Global Catastrophic Risks conference that was held in conjunction with Convergence 08 (and which I reprised for Convergence). I’m posting it here because it seems to me that this is exactly the kind of thing Foresight was founded for: to examine the revolutionary impacts of readily forseeable applications of nanotechnology.

In its present form, the Weather Machine is a work of futurism, not engineering. I have done only back-of-the-envelope calculations, and my assertions about what could be built are based more on instinct and educated guesses than on any major, deep engineering analysis. Even so, as a futurist I am fairly sure that something like the weather machine will be possible within the next few decades.
Read the rest of this entry »

Random clumps and tangles of carbon nanotubes are of limited use, but a method of depositing dense arrays of highly aligned carbon nanotubes on either rigid or flexible substrates promises transparent nanotech transistors for a variety of electronic applications. From the University of Southern California, via AAAS EurekAlert “USC researchers print dense lattice of transparent nanotube transistors on flexible base“:

It’s a clear, colorless disk about 5 inches in diameter that bends and twists like a playing card, with a lattice of more than 20,000 nanotube transistors capable of high-performance electronics printed upon it using a potentially inexpensive low-temperature process.

Its University of Southern California creators believe the prototype points the way to such long sought after applications as affordable “head-up” car windshield displays. The lattices could also be used to create cheap, ultra thin, low-power “e-paper” displays.

They might even be incorporated into fabric that would change color or pattern as desired for clothing or even wall covering, into nametags, signage and other applications.

A team at the USC Viterbi School of Engineering created the new device, described and illustrated in a just-published paper on “Transparent Electronics Based on Printed Aligned Nanotubes on Rigid and Flexible Structures” in the journal ACS Nano [abstract]. Read the rest of this entry »

A recent paper from Feynman Prize winner James Tour’s group at Rice
relates an interesting new form of memory based on a bistable 2-terminal
graphitic switch. Once developed, the switch could form the basis
of a high-density non-volatile storage which might replace flash devices
(which are already beginning to replace magnetic disks).

Rice press release

Read the rest of this entry »

The Allen Institute for Brain Science is using nanotech methods to map in which cells in the brain which genes are expressed, which should lead to new insights into the relationships among genes, brain regions, behavior, and disease. Such knowledge might also advance the development of ‘cognitive computing‘—the effort to build computers that mimic brains. From Nano World News, “A high-throughput platform for nanoparticle-based multiplex in-situ hybridization in brain“, written by Z. Riley and A. Jeromin:

Zackery Riley, BSc, MBA, is a senior research associate in the Methods Development group at the Allen Institute for Brain Science. Andreas Jeromin, PhD, is currently the manager of the Methods Development group at the Allen Institute for Brain Science. Their interest is focused on the development of novel and improved gene expression platforms and their integration with other high-throughput technologies.

The Allen Brain Atlas, developed by the Allen Institute for Brain Science, is the first large-scale atlas of gene expression in the mouse brain, using chromogenic in situ hybridization (cISH) to detect the location of over 20,000 genes. Read the rest of this entry »

Computational nanotech studies have shown that deliberate introduction of structural defects at specific sites in carbon nanotubes can guide electrons along specific paths, providing a way to fabricate complex electronic circuits from nanotubes. Although this research was theoretical, the researchers are quoted as saying focused electron beams could be used to create the defects where they would be needed to make complicated networks. An item on KurzweilAI.net led to this article on New Scientist Tech, written by Colin Barras. From “Flawed nanotubes could be perfect silicon replacement“:

The paradox of perfection — that flaws make things perfect — could be the key to designing nanoelectronic circuits from carbon nanotubes, according to US scientists.

They have discovered that a circuit of nanotubes can only guide a current if some of the tubes carry structural defects.

Individual carbon nanotubes are exceptionally good conductors because they are essentially a single carbon molecule. They can even outdo silicon at transmitting charge, which means nanotube circuits could boost computing speeds while reducing chip size… Read the rest of this entry »

Specially designed small RNA molecules have proven very effective in decreasing the expression of specific genes that cancer cells need to survive; however, getting these RNA molecules inside cancer cells in living animals is difficult. Using a promising nanotech approach to deliver the RNA molecules, a type of nanoparticle described as a neutral liposome was administered to mice bearing melanoma tumors and found to cause a significant decrease in tumor growth and in the number of metastatic tumor colonies. From the National Cancer Institute’s Alliance for Nanotechnology in Cancer “Nanoparticle Targets Melanoma With siRNA“:

Research has shown that a particular receptor for the blood protein thrombin is overexpressed by highly metastatic melanoma cells. When activated, this receptor triggers a wide range of biochemical changes that increase the metastatic activity of melanoma cells. To prevent those biochemical changes from occurring, a team of investigators at The University of Texas M.D. Anderson Cancer Center has developed a small interfering RNA (siRNA) agent designed to prevent melanoma cells from making this receptor, which is known as PAR-1, and used a lipid-based nanoparticle to deliver this agent to melanoma cells. Read the rest of this entry »

Previously unknown spectral properties of carbon nanotubes functionalized with DNA have been exploited to create nanotech sensors that can simultaneously detect several different substances, in real time, within living cells, to single molecule sensitivity. From “Nanotubes Track Cellular Toxins“, by Courtney Humphries, on the Technology Review web site:

Researchers at MIT have found that carbon nanotubes can serve as highly sensitive biological sensors for detecting single molecules in living cells in real time. The study, published online in Nature Nanotechnology [abstract], is the first demonstration that nanoscale sensors can be used to detect and image multiple types of molecules in cells at the same time, at a sensitivity that far exceeds that of fluorescent dyes, the standard tool for molecular imaging. The researchers used the sensors to detect substances that damage DNA, including certain cancer drugs and toxins. The sensors could eventually be used to monitor the effectiveness of chemotherapy drugs, track molecular interactions in cells, and test for low levels of toxins in the environment. Read the rest of this entry »

How well prepared is the FDA to regulate nanotech products? Perhaps not very well, at least in the area of dietary supplements. The Project on Emerging Nanotechnologies will release a report on FDA regulation of nanotechnology-based dietary supplements at an event to be held and webcast on January 14, 2009. For more information and to register to attend the event (No RSVP is required to view the webcast) see “Nanotech and Your Daily Vitamins“:

Historically, the regulation of dietary supplements has been a significant challenge for the U.S. Food and Drug Administration (FDA), and the fact that some of these products are now being manufactured using nanotechnology creates an additional layer of complexity.

A new report to be released at this event will address the question: Is FDA equipped to meet the emerging regulatory challenge of dietary supplements that use engineered nanomaterials? The short answer is no.

The FDA’s ability to regulate the safety of dietary supplements using nanomaterials is severely limited by lack of information, lack of resources and the agency’s lack of statutory authority in certain critical areas, according to a new Project report: A Hard Pill to Swallow: Barriers to Effective FDA Regulation of Nanotechnology-Based Dietary Supplements.

—Jim