Nanodot: the original nanotechnology weblog

Some nanostructures can be improved after fabrication by a new nanotech procedure that transiently and selectively liquifies the structures to remove defects. From “Self-perfection in nanomanufacturing“, a Nanowerk Spotlight written by Michael Berger:

…Rather than perfecting a nanostructure by improving its original fabrication method, researchers at Princeton University have demonstrated a new method, known as self-perfection by liquefaction (SPEL), which removes nanostructure fabrication defects and improves nanostructures after fabrication.

“When feature sizes in a device are small enough, the fabrication defects in many nanofabrication methods can become a dominant factor that determines the actual shape of the nanostructure” Dr. Stephen Y. Chou explains to Nanowerk. “Although extrinsic defects can be removed by improving the process, intrinsic defects caused by the fundamental statistical nature of a fabrication process — for example, noise in photon, electron or ion generation, scattering, and variations in chemical reaction — cannot be removed within the process regardless of improvements to it. The minimum line width and line height are often determined by the fundamental working principle of a fabrication, and are fixed once a fabrication method is selected.”

“Our process removes defects after fabrication rather than in the fabrication. As structures become very small, conventional fabrications will be limited by intrinsic noise, and improving the fabrication technology becomes fruitless.” Read the rest of this entry »

We’ve received an invitation to participate in the Center for Nanotechnology in Society’s project to build and critique nanotechnology scenarios.

Current topics to edit in the wiki, or you can add your own:
* Barless Prisons
* Bionic Eyes
* Living with a Brain Chip
* Disease Detector
* Automated Sewer Surveillance
* Engineered Tissues

Read the rest of this entry »

Studies of how molecules are released from nanoparticles when they encounter cancer cells and of how the nanoparticles break down prematurely while circulating in the blood point toward ways to improve the nanotech delivery of therapeutic drugs into cancer cells. From “Imaging yields insights into ‘nanomedicine’ for cancer treatment“, a Purdue University news release written by Emil Venere, via Nanowerk News:

Researchers at Purdue University have discovered a possible new pathway for anti-tumor drugs to kill cancer cells and proposed how to improve the design of tiny drug-delivery particles for use in “nanomedicine.”

The synthetic “polymer micelles” are drug-delivery spheres 60-100 nanometers in diameter, or roughly 100 times smaller than a red blood cell. The spheres harbor drugs in their inner core and contain an outer shell made of a material called polyethylene glycol.

Purdue researchers showed for the first time how this shell of polyethylene glycol latches onto the membranes of cancer cells, allowing fluorescent probes mimicking cancer drugs to enter the cancer cells, said Ji-Xin Cheng, an assistant professor in the Weldon School of Biomedical Engineering and Department of Chemistry. Read the rest of this entry »

Preliminary theoretical calculations show that it might be possible to develop a nanotech application in which clusters of a few boron atoms connect very small graphene semiconductors to make nanoelectronic devices. From nanotechweb.org, written by Belle Dumé (requires free registration) “Nanowiring using boron clusters“:

A model system that could serve as a “blueprint” for graphene-based nanodevices of the future has been put forward by scientists in Italy, Turkey and Germany. The model involves using alternating chains of boron clusters to connect various parts of a semiconducting graphene substrate. The concept is very similar to that routinely employed in silicon-based integrated circuits, but the resulting graphene-based devices would be several orders of magnitude smaller.

Graphene is set to become one of the key materials in future nanotechnology applications. However, graphene-based devices studied so far are on the micron rather than nanoscale because they mainly consist of broad sheets of graphene connected by wiring of about the same size.

Now, Jens Kunstmann of the Max-Planck Institute for Festkörperforschung in Stuttgart and colleagues have proposed a way to take the wiring down to the nanoscale by implanting chains of B7 clusters into the graphene matrix. These clusters might then be used to connect various areas of a semiconducting graphene substrate. Read the rest of this entry »

At the macro scale engineered motors are far more powerful than biological motors, but this has not been true with nanotech motors. Now, by adding carbon nanotubes to catalytic nanowires, nanotechnology has produced simple nanomotors that can surpass biological motors (somewhat). From the American Chemical Society, via AAAS EurekAlert “Go Speed Racer! Revving up the world’s fastest nanomotors“:

In a “major step” toward a practical energy source for powering tomorrow’s nanomachines, researchers in Arizona report development of a new generation of sub-microscopic nanomotors that are up to 10 times more powerful than existing motors.

In the new study, Joseph Wang and colleagues point out that existing nanomotors, including so-called “catalytic nanomotors,” are made with gold and platinum nanowires and use hydrogen peroxide fuel for self-propulsion. But these motors are too slow and inefficient for practical use, with top speeds of about 10 micrometers per second, the researchers say…

Wang and colleagues supercharged their nanomotors by inserting carbon nanotubes into the platinum, thus boosting average speed to 60 micrometers per second. Spiking the hydrogen peroxide fuel with hydrazine (a type of rocket fuel) kicked up the speed still further, to 94-200 micrometers per second. This innovation “offers great promise for self-powered nanoscale transport and delivery systems,” the scientists state.

The research is published in ACS Nano (abstract)
—Jim

Forests of spiraling nanotrees made from lead sulfide nanowires may lead to new nanotech approaches for producing one-dimensional nanostructures based on designed dislocations rather than metal catalysts to control growth. From the University of Wisconsin-Madison, via AAAS EurekAlert, “Spiraling nanotrees offer new twist on growth of nanowires“:

Since scientists first learned to make nanowires, the nano-sized wires just a few millionths of a centimeter thick have taken many forms, including nanobelts, nanocoils and nanoflowers.

But when University of Wisconsin-Madison chemistry professor Song Jin and graduate student Matthew Bierman accidentally made some pine tree shapes one day — complete with tall trunks and branches that tapered in length as they spiraled upward — they knew they’d stumbled upon something peculiar.

… Writing in the May 1 edition of Science Express [abstract], Jin and his team reveal just how curious the nanotrees truly are. In fact, they’re evidence of an entirely different way of growing nanowires, one that promises to give scientists a powerful means to create new and better nanomaterials for all sorts of applications, including high-performance integrated circuits, biosensors, solar cells, LEDs and lasers. Read the rest of this entry »

RNA interference (RNAi) is a way to decrease expression of a specific gene without otherwise affecting the cell, and it therefore could be a very promising treatment for a wide variety of diseases—if it could be reliably delivered into the diseased cell cytoplasm. One possible nanotech solution to this problem takes the form of a 10-fold more effective delivery of RNAi protected in nanocapsules formed by novel lipid-like molecules. From “Nano RNA delivery: Novel delivery agents could mean a more targeted way to turn off disease genes” at Technology Review, written by Kevin Bullis (credit to KurzweilAI.net):

An experimental and potentially powerful way to fight disease, called RNA interference (RNAi), could now be closer to reality, as researchers at MIT and Alnylam, a biotech company based in Cambridge, MA, have addressed a key obstacle to effectively delivering the treatment to targeted cells. The researchers report a method for quickly synthesizing more than a thousand different lipid-like molecules and screening them for their ability to deliver short RNA molecules to cells. They’ve shown that some of these delivery agents are 10 times as effective at delivering RNA than previous methods were. Read the rest of this entry »

Nanotechnology has provided a fourth fundamental two-terminal passive element for electronic circuits—one first theoretically predicted 37 years ago, but only made physically possible by nanotechnology. Now joining resistors, capacitors and inductors is a nanotech device named the ‘memristor’, developed by a team led by R. Stanley Williams, who shared the 2000 Foresight Nanotech Institute Feynman Prize for Experimental work. From “H.P. Unveils New Memory Technology“, written by John Markoff for The New York TImes:

A team of Hewlett-Packard scientists reported Wednesday in the science journal Nature [abstract] that they have designed a simple circuit element they believe will enable tiny powerful computers that could imitate biological functions.

The device, called a memristor, could make it possible to build extremely dense computer memory chips that use far less power than today’s DRAM memory chips, which are rapidly reaching the limit in how much smaller they can be made.

The memristor, an electrical resistor with memory properties, may also make it possible to fashion advanced logic circuits, like a class of reprogrammable chips known as field programmable gate arrays, that are today widely used for rapid prototyping of new circuits and for custom-made chips that need to be manufactured quickly. Read the rest of this entry »

A special issue of the International Journal of Nanomanufacturing presenting topics on manufacturing in 3D at the nanoscale (derived from the 4th International Symposium on Nanomanufacturing held at MIT in November 2006) contains a report of a nanomanipulator for the complex assembly of nanoparticles. Although the press release from Inderscience Publishers, via AAAS EurekAlert (”Are nanobots on their way? US researchers have built a proto-prototype nano assembler“) explicitly references Eric Drexler’s 1986 description of an assembler, it is not clear (to me) from what is presented how close this mechanism might come to atomically precise manufacturing.

…Jason Gorman of the Intelligent Systems Division at the US government’s National Institute of Standards and Technology (NIST) … and his colleagues at NIST have taken a novel approach to building a nanoassembler and reveal details in a forthcoming issue of the International Journal of Nanomanufacturing [abstract]. “Our demonstration is still a work in progress,” says Gorman, “you might describe it as a ‘proto-prototype’ for a nanoassembler.”

…The NIST system consists of four Microelectromechanical Systems (MEMS) devices positioned around a centrally located port on a chip into which the starting materials can be placed. Each nanomanipulator is composed of positioning mechanism with an attached nanoprobe. By simultaneously controlling the position of each of these nanoprobes, the team can use them to cooperatively assemble a complex structure on a very small scale. “If successful, this project will result in an on-chip nanomanufacturing system that would be the first of its kind,” says Gorman. Read the rest of this entry »

A new building block for structural DNA nanotechnology uses a 3-carbon glycerol molecule instead of the 5-carbon sugar deoxyribose found in DNA. To begin exploring this new DNA nanotech, the researchers made a simple four-helix junction of the type pioneered in Ned Seeman’s laboratory, and found that nanostructures built from GNA not only tolerate higher temperatures than do comparable structures made with DNA, but both left-handed and right-handed four-helix junctions are obtained—something not easily done with DNA. An excerpt from “Scientists make chemical cousin of DNA for use as new nanotechnology building block” from Arizona State University, via AAAS EurekAlert:

In the Biodesign Institute at Arizona State University, researchers are using DNA to make intricate nano-sized objects. Working at this scale holds great potential for advancing medical and electronic applications. DNA, often thought of as the molecule of life, is an ideal building block for nanotechnology because they self-assemble, snapping together into shapes based on natural chemical rules of attraction. This is a major advantage for Biodesign researchers like Hao Yan, who rely on the unique chemical and physical properties of DNA to make their complex nanostructures.

While scientists are fully exploring the promise of DNA nanotechnology, Biodesign Institute colleague John Chaput is working to give researchers brand new materials to aid their designs. In an article recently published in the Journal of the American Chemical Society [abstract], Chaput and his research team have made the first self-assembled nanostructures composed entirely of glycerol nucleic acid (GNA)—a synthetic analog of DNA. Read the rest of this entry »

The nanotechnology of engineering atomic layer interfaces to produce desired properties—in this case, something called ‘improper ferroelectricity’—promises a technological revolution that may be comparable to the development of modern electronics. From a Stony Brook University news release via ScienceDaily:

In the 10 April issue of Nature [abstract], a new artificial material is revealed that marks the beginning of a revolution in the development of materials for electronic applications…

The new material, a superlattice, which has a multilayer structure composed of alternating atomically thin layers of two different oxides (PbTiO3 and SrTiO3), possesses properties radically different to either of the two materials by themselves. These new properties are a direct consequence of the artificially layered structure and are driven by interactions at the atomic scale at the interfaces between the layers.

“Besides the immediate applications that could be generated by this nanomaterial, this discovery opens a completely new field of investigation and the possibility of new functional materials based on a new concept: interface engineering on the atomic scale,” said [one of the lead researchers Dr. Matthew] Dawber.

Transition metal oxides are a class of materials that provoke great interest because of the great diversity of properties which they can present (they can be dielectrics, ferroelectrics, piezoelectrics, magnets or superconductors) and their ability to be integrated into numerous devices. The majority of these oxides possess a similar structure (referred to as ‘perovskite’) and, recently, researchers have developed the ability to build these kinds of materials up, atomic layer by atomic layer, much as a child plays with Lego bricks, hoping to produce new materials with exceptional properties.

—Jim

To round out our week in nanotech on an upbeat note, we have Caltech professor Michael Roukes‘ podcast over at Earth & Sky: Forever Young. In addition to the podcast, and there’s more at the Power of Small television show on medical applications of nanotechnology, which also appears to use the title Forever Young. From the Earth & Sky site:

Michael Roukes: “It’s become clear that we can think about biological systems, medical systems, in the same way we think about bits of information flowing through digital computers.”

That’s research scientist Michael Roukes, who’s with the Kavli Nanoscience Institute at Caltech. He’s talking about nanotechnology and medicine.

Michael Roukes: “I think the most profound – I use this word repeatedly – transformative potential that this technology has is to basically democratize modern medicine.”

In other words, nanotech has the potential to instantly diagnose and treat disease.

Bring it on! —Christine

A nanotechnology approach is being developed to selectively kill cancer cells—even those resistant to normal chemotherapy—using a peptide decorated with organic molecules called crown ethers. The peptide nanostructure is activated by a protein-cutting enzyme found on certain cancer cells so that the activated peptide aligns the crown ethers to punch holes in the cancer cell membranes. From Chemical Biology, written by Kathleen Too “Peptides provide fatal blow for cancer cells“, via Nanowerk News:

Peptide nanostructures that punch holes in cancer cells are ‘the first step towards efficient nanochemotherapeutics,’ say chemists in Canada.

Normand Voyer and colleagues at the University of Laval in Québec have designed a series of modified peptide nanostructures that can puncture cancer cell membranes, leading to the cells’ death.

The team explains that in the past decade, cancer cell resistance to chemotherapeutic agents has led to increased cancer deaths. ‘We believe that nanochemotherapeutics can overcome this problem due to the particular properties of nanometre-sized compounds,’ says Voyer. Read the rest of this entry »

By combining a nanofluidics device to stretch out a single long DNA molecule with a strategy to read five DNA letters at a time, two companies are applying nanotechnology to develop a really cheap method to sequence individual genomes to make possible individualized medicine. From “The $100 Genome“at Technology Review, written by Emily Singer, via KurzweilAI.net:

Forget the $1,000 genome. Some companies are looking far past that goal to create a really inexpensive sequencing technology.

It currently costs roughly $60,000 to sequence a human genome, and a handful of research groups are hoping to achieve a $1,000 genome within the next three years. But two companies, Complete Genomics and BioNanomatrix, are collaborating to create a novel approach that would sequence your genome for less than the price of a nice pair of jeans–and the technology could read the complete genome in a single workday. “It would have been absolutely impossible to think about this project 10 years ago,” says Radoje Drmanac, chief scientific officer at Complete Genomics, which is based in Mountain View, CA. Read the rest of this entry »

Accurate computational simulations of molecular movements are important tools for developing atomically precise nanotechnology systems because how the atoms move under different conditions can determine whether or not the nanotech device works as designed. A new method of measuring “blurred” molecular motions promises to improve the accuracy of molecular motion simulations. From an Argonne National Laboratory News Release “Argonne scientists develop techniques for creating molecular movies” via KurzweilAI.net:

They may never win an Oscar, but scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory have developed techniques for creating accurate movies of biological and chemical molecules, a feat only theorized up until now.

Biological and organic molecules in solution are far more complex than the standard crystalline structures of salt or metals since they are constantly moving and changing over time. These motions have not yet been seen directly, but scientists using the high-intensity X-rays at the Advanced Photon Source have measured images that are “blurred” by these motions and have used them to create more accurate movies of molecular motions. Read the rest of this entry »

Foresight advisor Glenn Reynolds opines about nanotech in the NY Post for Earth Day:

MIT’s Vladimir Bulovic calls nanotech a potentially “disruptive technology” in the solar-energy field, offering a complete shift from today’s fossil-fuel environment…

Nanotech offers dramatic improvements on the side of energy consumption, too: As computing and other devices become smaller, they become more efficient - and nanotech will allow drastic improvements in both size and efficiency.

Nanotech is starting to yield super-strong, super-light materials, too. Imagine how much more efficient a family car could be if you cut the weight in half, even if you kept burning gas. But nanotech is also likely to produce better batteries and better motors, meaning that your lighter car may also be electric, powered ultimately by those nanodot solar panels.

All of these things are in the works now to greater and lesser degrees, but they could happen faster if there were more research and development support.

Ultimately, we’re probably better off putting our energies into promoting cleaner, more advanced technologies like these than in trying to get people to reduce the scope of their lives through “hair-shirt environmentalism.”

Hair-shirts have always had their fans, but have seldom been widely adopted. On the other hand, most people would like to lead cleaner, better, more efficient lives. Why not give ‘em what they want, and help the planet at the same time?

A focus on cutting energy consumption with today’s technology isn’t going to make much of a difference. Let’s work on replacing current tech with something better, instead.

Let’s try for the win-win scenarios. —Christine

In the rush of nanotechnology toward molecular-scale electronics for computers, graphene has now been shown to retain essential properties when used to make transistors at the one-nanometer-scale. However, reliable fabrication of devices at this size scale remains an obstacle. From a University of Manchester press release “Graphene used to create world’s smallest transistor” via ScienceDaily

Researchers have used the world’s thinnest material to create the world’s smallest transistor, one atom thick and ten atoms wide.

Reporting their peer-reviewed findings in the latest issue of the journal Science [abstract], Dr Kostya Novoselov and Professor Andre Geim from The School of Physics and Astronomy at The University of Manchester show that graphene can be carved into tiny electronic circuits with individual transistors having a size not much larger than that of a molecule.

…Unlike all other known materials, graphene remains highly stable and conductive even when it is cut into devices one nanometre wide. Read the rest of this entry »

It’s great to see ambitious goals being set in nanotechnology, like these “molecular mini-factories“.

Researchers from a wide range of disciplines at Eindhoven University of Technology (TU/e) will be joining forces in the Institute for Complex Molecular Systems (ICMS). They will be investigating the exact mechanism behind self-organization, the principle behind all life on earth. Researchers plan to use this knowledge to build molecular mini-factories that could produce the next generation of catalysts, photosynthetic systems, nanocontainers and functional materials. Prof. Bert Meijer will head the institute. The Executive Board of the university decided last week to allocate 15 million euros to the institute over the next 10 years.

Looking to nature as a model, TU/e scientists and engineers from the fields of mathematics, chemistry, physics and biology are taking on a tremendous challenge: to force a breakthrough in research into self-assembly among molecules. This is the next step toward manufacturing complex functional systems. Given the enormous possibilities afforded by nanoscience and microtechnology, researchers should be able to regulate the interactions between molecules such that the right molecular complex is formed. It is a highly complicated system where chemical and physical phenomena on different time and length scales come together.

Work such as this is on the pathway to productive nanosystems (see Roadmap). Credit: Nanoforum.org. –Christine

In a proof-of-concept demonstration, large area graphene films several atomic layers thick were inexpensively produced. These films are not perfect single atomic layers of carbon, as are the much smaller graphene flakes that have been produced up to now, but the researchers are confident that they can improve the films over time. A chemistry professor not involved in this research, molecular nanotechnology pioneer James Tour, is referenced as believing these films hold great promise for organic solar cells. Excerpts from “How to Make Graphene: A simple way to deposit thin films of carbon could lead to cheaper solar cells“, by Prachi Patel-Predd at Technology Review:

Graphene—a flat single layer of carbon atoms—can transport electrons at remarkable speeds, making it a promising material for electronic devices. Until recently, researchers had been able to make only small flakes of the material, and only in small quantities. However, Rutgers University researchers have developed an easy way to make transparent graphene films that are a few centimeters wide and one to five nanometers thick.

Thin films of graphene could provide a cheap replacement for the transparent, conductive indium tin oxide electrodes used in organic solar cells. They could also replace the silicon thin-film transistors common in display screens. Graphene can transport electrons tens of times faster than silicon, so graphene-based transistors could work faster and consume less power… Read the rest of this entry »

Two weeks ago we cited a research effort using metallic nanorods to store a petabyte on an optical disk. Now comes a report that nanotechnology using a molecular-scale switch could enable storing half a petabyte on one square inch. This nanotech advance uses a polyoxometalate (POM) molecular cluster that can be reversibly interconverted between two electronic states. From a news release from the University of Glasgow “Nanotechnology paves way for super iPods” via Nanowerk News:

A breakthrough by scientists from the University of Glasgow could see the storage capacity of an iPod increase 150,000 times.

Nanotechnology researchers have developed a molecule-sized switch which means that data storage can be dramatically increased without the need to increase the size of devices.

Professor Lee Cronin and Dr Malcolm Kadodwala’s work would see 500,000 gigabytes squeezed onto one square inch. The current limit for the space is around 3.3 gigabytes.

…Professor Lee Cronin said: “What we have done is find a way to potentially increase the data storage capabilities in a radical way.

“We have been able to assemble a functional nanocluster that incorporates two electron donating groups, and position them precisely 0.32 nm apart so that they can form a totally new type of molecular switching device. Read the rest of this entry »