Nanotech and Biotech Consulting

It is with great sadness that we report the death of Prof. Arthur Kantrowitz, a founding Advisor of Foresight Institute and an early supporter of molecular nanotechnology concepts when they were first developed at MIT in the late 1970s by then-student K. Eric Drexler.

Arthur was an amazingly innovative scientist and technologist, as described in his Wikipedia entry, which is worth reading. The fact forums described in Engines of Creation were an extension of Arthur’s Science Court concept.

To be inspired, read his essay The Weapon of Openness which guides Foresight’s work today, especially in the area of Open Source Sensing. We’ll miss his wisdom.

It’s hard to say goodbye to this wonderful long-time friend. —Chris Peterson

A nanostructure called a “gyroid” self-assembled from diblock copolymers provides a scaffold with the proper dimensions so that when light knocks electrons loose from a dye molecule, the electrons and the holes left behind can be separated to obtain an electric current, providing the basis for a more efficient, inexpensive nanotech solar cell. PhysOrg.com points us to this Cornell University news article by Bill Steele, “Nanomanufactured polymer film could lead to lower-cost solar cells“:

You never know where basic research may lead. For decades materials scientists have been experimenting with a corkscrew-like polymer structure called a gyroid. Now an international team of researchers has shown that the gyroid structure can be used to “self-assemble” a low-cost photovoltaic cell.

The idea could lead to more economical solar collectors and more efficient fuel cells.

The prototype is a variation on the Graetzel solar cell, which uses an organic dye sandwiched between two conductors. Forming the conductors into an interlocking corkscrew allows current to be transported out efficiently. The team’s first cell, made in a thin film 400 nanometers thick, has a conversion efficiency ranging from 0.7 to 1.7 percent — low compared with silicon-based photocells, but “amazing” for such a thin film, said Ulrich Wiesner, the Spencer T. Olin Professor of Materials Science and Engineering at Cornell.

“The next step is to make it thicker” so more of the light falling on it can be captured, he said. “We hope that we will eventually get efficiencies that rival silicon-based devices.” Currently available silicon-based solar cells convert about 15 percent of the energy of the light falling on them to electricity, although some new designs promise higher efficiencies.

The work by Wiesner and scientists at the Universities of Cambridge and Oxford in Britain, the Freiburg Institute for Advanced Studies in Germany, Institute Curie in France and the University of Minnesota, Minneapolis, is described in the online version of the journal Nano Letters [abstract] ….

…the researchers assembled a copolymer gyroid film, then dissolved away just the corkscrew part of the structure, leaving a corkscrew-shaped mold that they filled with titanium oxide. Heating then burned off the other polymer part and crystallized the titanium oxide into a solid structure that conducts electrons. This was coated with a light-sensitive dye, and finally the space around it was filled with a material that conducts “holes” (positive charges).

When light strikes the dye it knocks loose electrons, which flow into the titanium oxide framework, while the holes left behind flow into the other conductor. Electrodes above and below the film carry off the resulting current.

The secret of a solar cell, Wiesner explained, is that the electron-hole pairs must find the interface between the two conductors within 10 nanometers (about the width of 30 atoms) so they can separate and flow away, or they will recombine.

“This is why block copolymers are exciting,” Wiesner said, “because that is the characteristic length scale of separation of the two blocks.”

—Jim

The agreement between ConocoPhillips and the University of Kansas (KU) will focus on a research project dedicated to developing nanoscale technologies for enhanced oil recovery. The university recently established a nanotech research center, and has been involved in oil recovery research for more than 30 years. Under the program, KU will develop polymers that ConocoPhillips will then test in the field.

To the list of the amazing properties of carbon nanotubes has been added the ability to make nanotech loudspeakers that produce sound without mechanical movement. From nanotechweb.org, written by James Tyrrell (requires free registration): “CNT loudspeaker rips up the design book“:

A transparent carbon nanotube (CNT) thin film developed by Lin Xiao and colleagues at Tsinghua University, China, could turn out to be a wonder material for makers of audio visual devices. The see-through structure emits sound when hooked up to an electrical signal and can be stretched over a display to play audio content … eliminating the need for conventional loudspeakers or headphones.

To emit sound, the device relies on the so-called thermoacoustic effect. In other words, it is the thermal expansion and contraction of air in the vicinity of the thin film (due to the periodic heating of the CNTs) that produces sound, not the mechanical movement of the thin film itself.

…”We can batch-synthesize super-aligned CNT arrays onto 4 inch silicon wafers, which each provide enough material for a continuous thin film that can be up to 60 m long and up to 10 cm wide,” the researchers told nanotechweb.org. “Because the thin film itself does not vibrate, the loudspeaker will continue to work even if part of the film is broken or if the device is mounted on soft materials such as flags or clothing.”

The research was published in Nano Letters (abstract). The researchers also provide videos of the CNT loudspeaker working. The two links included in the nanotechweb.org article did not work for me, but the Nano Letters abstract includes the following links under “Available Supporting Information for This Article” that did work, and I found the sound to be quite respectable.

QuickTime Video

• nl802750z_si_002.qt (3.55 MB)
• nl802750z_si_003.qt (3.96 MB)
• nl802750z_si_004.qt (3.6 MB)

Microsoft Video (AVI)

• nl802750z_si_005.avi (4.29 MB)

—Jim

The Australian Office of Nanotechnology in the Department of Innovation, Industry, Science and Research has announced the launching of AccessNano, a nanotechnology resource for secondary schools.

Research conducted by Tahir Cagin, a professor in the Artie McFerrin Department of Chemical Engineering at Texas A&M University, and his partners from the University of Houston, has led to a significant discovery in the area of power harvesting.

Researchers at the Australian National University (ANU) have succeeded in using plasma technology to potentially reduce the cost of manufacturing a fuel cell.

One group of researchers has developed a method to chemically coat single-walled carbon nanotubes (SWNTs) to produce a nanotech assay for trace levels of proteins associated with cancer that is a thousand fold more sensitive than are current assays. A second group developed a mathematical method to permit analysis of samples for several proteins at the same time. From the National Cancer Institute’s Alliance for Nanotechnology in Cancer “Carbon Nanotubes Improve Protein Array Detection Limits“:

To detect cancer as early as possible, dozens of research groups are developing methods to detect trace levels of cancer-related proteins and genes in blood or other biological samples. Those efforts should get a boost thanks to new research results showing that carbon nanotubes can serve as incredibly sensitive optical labels for use in a wide variety of assay systems.

Reporting its work in the journal Nature Biotechnology [abstract], a research team headed by Hongjie Dai, Ph.D., Stanford University and the Center for Cancer Nanotechnology Excellence Focused on Therapeutic Response, describes a new type of coating developed specifically for attaching any number of different types of targeting agents to the surface of single-walled carbon nanotubes. This coating, a branched form of the biocompatible polymer poly(ethylene glycol) (PEG), enabled the investigators to readily couple antibodies to carbon nanotubes. In the experiments reported in their current paper, the antibodies were designed to identify specific proteins immobilized on a standard protein array microchip.

Carbon nanotubes can function as bright Raman optical tags that are readily detected when irradiated with light. Experiments comparing the lower limits of protein detection using an antibody-labeled carbon nanotube tag and a standard fluorescence tag showed that the carbon nanotube-enabled assay was at least 1,000 times more sensitive than the fluorescence assay. At least part of this improvement resulted from the almost total elimination of background fluorescence that can confound other detection schemes. In addition, the investigators found that the Raman tags were useful over a larger range of concentrations, ranging from 10 nanomoles to 1 femtomoles. The investigators note in their paper that the coating they developed also should enable them to create Raman tags that can detect nucleic acids and other types of biomolecules.

Meanwhile, a second group of investigators, led by Beatrice Knudsen, M.D., Ph.D., Fred Hutchinson Cancer Research Center, and Selena Chan, Ph.D., Intel Corporation, has developed a mathematical technique for analyzing the specific spectral output of different Raman probes, making it possible to create highly multiplexed assays using these probes. Unlike traditional fluorescent labels that typically absorb and emit light in a very narrow band of frequencies, Raman probes generate complex frequency spectra that are chock-full of information.

The Knudsen-Chan team, which published its results in the journal ACS Nano [abstract], developed a method for sorting out the various spectral peaks associated with individual nanoscale Raman probes that were part of a mixture of these probes. Each probe was designed to bind to a different biomolecule. In one experiment, the investigators were able to decipher a complex Raman spectrum that included the optical emission from three different Raman probes and thereby determine the amount of each probe in the mixture. The researchers note that their method for spectral analysis is exceedingly simple to conduct and is amenable to high-throughput analysis in any type of multiplexed assay system.

—Jim

The NanoforumEULA (Nanoforum European Union and Latin America) has released a report detailing the results of fact-finding missions about the state of nanotechnology research and policy in Mexico, Argentina, and Brazil between 2007-2008.