Archive for September 30th, 2006|Daily archive page

Nanotube Scaffolds for Neural Implants

In Health, nano on September 30, 2006 at 7:44 pm

Friday, September 22, 2006
Tiny carbon fibers are helping stem cells to grow in stroke-damaged brains.

By Jennifer Chu
Stem cells are a promising therapy for stroke and other brain injuries–they can sprout into healthy neurons and may be able to re-establish brain activity in brain-injured patients. While preliminary animal research shows promise, there’s often a common hurdle: adult stem cells have a hard time growing in damaged areas and tend to migrate to healthier regions of the brain.

That makes sense, says Thomas Webster, associate professor of engineering at Brown University, because healthy neurons emit proteins that attract stem cells away from diseased, inactive areas. What’s needed is an “anchor” to keep stem cells fixed to the damaged areas, where they can then differentiate into working neurons, he says.

Webster and his collaborators in South Korea found a possible anchor in carbon nanotubes: tiny, highly conductive carbon fibers that not only act as scaffolds, helping stem cells stay rooted to diseased areas, but also seem to play an active role in turning stem cells into neurons.

Just how this works isn’t clear, but the researchers say their initial results could someday be engineered into a stem cell delivery device for stroke therapy. Webster presented the team’s findings at the American Chemical Society meeting this month in San Francisco.

Prior to this experiment, Webster had been experimenting with the properties of carbon nanotubes as possible neural implant material. Since nanotubes are highly conductive, they’re an ideal template for transmitting electrical signals to neurons. In 2004, Webster was able to stimulate neurons to grow multiple nerve endings along carbon nanotubes. The study attracted the attention of South Korean stroke researchers, who proposed a collaboration: Why not use carbon nanotubes as a template for adult stem cells to grow into neurons? Taking it one step further, the team injected this nano-cocktail directly into the stroke-damaged brain regions of rats.

In order to determine how well the two therapies work together, the team compared the effects of injections of both stem cells and nanotubes with control groups injected with only adult stem cells or carbon nanotubes. After one and three weeks, researchers sacrificed the rats and examined the diseased areas of their brains. In rats who had received only adult stem cells, the cells tended to stray to healthier regions of the brain. But rats given both nanotubes and cells showed new neural growth in stroke-damaged brain regions in as little as a week…….
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Kavli Institute for Bionano Science and Technology established

In Health, nano on September 30, 2006 at 7:39 pm

Gift will support the exploration of life and biology at the nanoscale level

The Kavli Foundation and Harvard University have agreed to establish the Kavli Institute for Bionano Science and Technology (KIBST). The endowment from the Kavli Foundation will help to boost the University’s research efforts at the interfaces of biology, engineering, and nanoscale science. In particular, the gift will fund postdoctoral research fellows and support a lectureship series dedicated to “nano-” or small-scale science.

A “nanometer” is one-billionth of a meter, about a 100,000 times smaller than the diameter of the average human hair. Nanoscience offers scientists a way to get a close-up view of life’s building blocks – near-atomic-resolution images that help to determine the structure and function of proteins and even to follow the dynamics of individual molecules. Likewise, advances in manipulating nanoscale matter and materials are likely to lead to tiny machines that could deliver medicine or detect viruses.

“Fred Kavli’s gift on behalf of his foundation is a wonderful commitment to both the basic and applied sciences,” said Harvard’s interim President Derek Bok. “It will allow Harvard to build an even stronger presence in this exciting and emerging field.”

“Some of the most fascinating scientific research today is being done at the nanoscale, the realm of atoms and molecules,” said business leader and philanthropist Fred Kavli, founder of the Kavli Foundation. “I expect that the Harvard institute will contribute significantly to our knowledge of nanoscale processes, and help to harness them for the benefit of humanity.”

George Whitesides, Woodford L. and Ann A. Flowers University Professor, and David Weitz, Mallinckrodt Professor of Physics and of Applied Physics, will serve as the founding directors for the KIBST. The institute, which is expected to reside in either the future Laboratory for Integrated Sciences and Engineering or Northwest buildings, will complement Harvard’s existing hubs dedicated to small-scale science: the Center for Nanoscale Systems (CNS), the Materials Research Science and Engineering Center (MRSEC), the Nanoscale Science and Engineering Center (NSEC), and the newly formed Initiative in Quantum Science and Engineering (IQSE).

“The KIBST will seek to develop a deeper understanding of the functioning of life and biology at the nanoscale level by developing new tools and probes that marry microfabrication and microfluidics with high-resolution imaging,” said Whitesides. “Our goals are to use such new techniques to probe the behavior of single molecules, cells, tissue, and organs; to gain a deeper understanding of the essential relationship between structure and function that controls all biology; and to combine structural and functional studies from the scale of single molecules to the scale of tissues and whole organs.”

The Harvard Division of Engineering and Applied Sciences (DEAS), with almost half of its faculty having some interest in biology-related questions and with its increasingly strong ties to the Harvard Medical School, will play a large role in shaping the direction of the institute. In addition, participants in the KIBST will span various departments in Harvard’s Faculty of Arts and Sciences – such as Chemistry and Chemical Biology, Molecular and Cellular Biology, Organismic and Evolutionary Biology, Physics, and Statistics – and include researchers from broader science initiatives such as those in neuroscience, genomics, and the Rowland Institute.

“While there are a number of faculty already engaged in research on various aspects of bionano science and technology, the establishment of the Kavli Institute will help to further integrate these activities by providing an umbrella institution,” said Venkatesh “Venky” Narayanamurti, dean of engineering and applied sciences. “Investing at the interfaces of fields is critical for sustaining continued advances across areas in science and engineering. Future innovations might range from new types of imaging devices to smart drug delivery systems to novel materials.”

Co-directors Whitesides and Weitz expect the KIBST’s initial efforts to be focused on applying advances from the physical sciences, particularly at the nanoscale level, to the study of important questions in the life sciences. One area of considerable interest involves using microfluidic techniques (the precise control and manipulation of extremely small volumes of fluids) to better understand biological problems at the level of cells and below.

“The Kavli Institute for Bionano Science and Technology is an important addition to the expanding network of Kavli institutes,” said David Auston, president of the Kavli Foundation. “We expect it will play a key role in advancing the frontiers of science in this emerging field where biology, physics, chemistry, and materials science intersect.”

About the Kavli Foundation

Dedicated to the advancement of science for the benefit of humanity, the Kavli Foundation supports scientific research, honors scientific achievement, and promotes public understanding of scientists and their work through an international program of research institutes, prizes, professorships, and symposia in the fields of astrophysics, nanoscience, and neuroscience. Established in 2000, its headquarters are in Oxnard, Calif.
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Dip-pen nanolithography

In nano on September 30, 2006 at 2:26 am

Friday, September 29, 2006
How To Pin Down 55,000 Virus Particles

Nanotechnology gets a speed boost with a new tool made of thousands of pens.

By Kevin Bullis
Researchers have developed a device that uses 55,000 perfectly aligned, microscopic pens to write patterns with features the size of viruses. The tool could allow researchers to study the behavior of cells at a new rate of speed and level of detail, potentially leading to better diagnostics and treatments for diseases such as cancer.

The device builds on a technique called dip-pen nanolithography, which was first developed in 1999 by Chad Mirkin, professor of chemistry, medicine, and materials science and engineering at Northwestern University. In that system, the tip of a single atomic force microscope (AFM) probe is dipped in selected molecules, much as a quill pen would be dipped in ink. Then the molecules slip from the tip of the probe onto a surface, forming lines or dots less than 100 nanometers wide. Their size is controlled by the speed of the pen.

Because it operates at room temperature, the dip-pen tool is particularly useful for working with biological materials, such as proteins and segments of DNA that would be damaged by high-energy methods like electron beam lithography. Also, the patterns it makes can be easily programmed, making it “probably the best rapid-prototyping system for nanostructures out there,” Mirkin says.

The method addresses “one of the biggest problems in nanoscience,” according to Mirkin. “How do I get fingers small enough to manipulate something so small I can only see it with an electron microscope?” Because the tool can work at that scale “routinely,” he says, “I think it’s going to turn everything upside-down.”

So far, applications of the single-pen device, which is already being sold through NanoInk, a company based in Chicago, have been limited because of the speed of the process. “The drawback of [dip-pen nanolithography] in its early years was that it was slow if you wanted to prepare substrates that were patterned over large areas,” on the scale of a square centimeter, says Milan Mrksich, professor of chemistry at the University of Chicago (who was not involved with the work).

Mirkin and colleagues have overcome this problem by creating a massive array of pens using conventional photolithography. “The 55,000-pen array greatly accelerates the patterning rate,” Mrksich says, “increasing the throughput by orders of magnitude.” Mirkin says the pens can now write “hundreds of millions of features on a minute time-scale.”

In a paper appearing online now in the journal Angewandte Chemie, Mirkin described test runs with the array that show the complexity of the patterns that are possible. For example, he simultaneously printed 55,000 identical microscopic nickels in an area smaller than a dime. The dots outlining Jefferson’s face are each only 80 nanometers wide……
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