Scientists Create the First Synthetic Nanoscale Fractal Molecule

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Scientists Create the First Synthetic Nanoscale Fractal Molecule, Thursday May 11, 2006 by ANDREA GIBSON

ATHENS, Ohio – From snowflakes to the leaves on a tree, objects in nature are made of irregular molecules called fractals. Scientists now have created and captured an image of the largest man-made fractal molecule at the nanoscale.

The molecule, developed by researchers at the University of Akron, Ohio University and Clemson University, eventually could lead to new types of photoelectric cells, molecular batteries and energy storage, according to the scientists, whose study was published online today by the journal Science.

A University of Akron research team led by Vice President for Research George Newkome used molecular self-assembly techniques to synthesize the molecule in the laboratory. The molecule, bound with ions of iron and ruthenium, forms a hexagonal gasket.

Ohio University physicists Saw-Wai Hla and Violeta Iancu, who specialize in imaging objects at the nanoscale, confirmed the creation of the man-made fractal. To capture the image, the physicists sprayed the molecules onto a piece of gold, chilled them to minus 449 degrees Fahrenheit to keep them stable, and then viewed them with a scanning tunneling microscope.

Though invisible to the naked eye – the molecules are about one million times smaller than the colorful hexagons shown in the Science image – the objects are 12 nanometers wide. “That’s big for a nanoscale molecule. It’s huge,” said Hla, an associate professor of physics and astronomy.

“This man-made structure is one of the first nanoscale, non-branched fractal molecules ever produced,” said Newkome, who is lead author on the Science paper and also serves as dean of the Graduate School and the James and Vanita Oelschlager Professor of Science and Technology at the University of Akron. “Blending mathematics, art and science, these nanoscopic hexagonal-shaped materials can be self-assembled and resemble a fine bead necklace. These precise polymers — the first example of a molecule possessing a ‘Star of David’ motif — may provide an entrée into novel new types of photoelectric cells, molecular batteries and energy storage.”

Fractals are irregular curves or shapes that retain the same pattern when reduced or magnified. The molecule in the study, for example, is composed of six rings, which are made up of six smaller rings, and so on, Hla explained. Snowflakes, broccoli florets or tree bark would be just a few examples from nature.

Hla and Iancu, a graduate student, also were able to measure the electronic structure of the molecule, which is useful to know for possible electronic applications. “(The molecules) are unique in their own way, so you have to find out what kind of properties they have so we can initiate possible applications,” he said.

The study authors were George R. Newkome, Pingshan Wang, Charles N. Moorefield, Tae Joon Cho, Prabhu Mohapatra, Sinan Li, Seok-Ho Hwang and Judith A. Palagallo, all from the University of Akron; Violeta Iancu and Saw-Wai Hla of Ohio University; and Olena Lukoyanova and Luis Echegoyen of Clemson University.

The research was supported by the National Science Foundation, Air Force Office of Scientific Research and the Ohio Board of Regents.

Hla is a member of Ohio University’s Nanoscale & Quantum Phenomena Institute, Condensed Matter and Surface Science group and Biomimetic Nanoscience and Nanotechnology group, which is part of Ohio University’s $8 million NanoBioTechnology Initiative, one of three major research priorities of the institution.

Read the article on Science Express or contact @Science for a copy. Contacts at Ohio University: Saw Wai-Hla, (740) 593-1727, hla@helios.phy.ohiou.edu; Andrea Gibson, (740) 597-2166, gibsona@ohio.edu Media Contact at University of Akron: Ken Torisky, (330) 972-7299.

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World’s tiniest test tubes get teensiest corks

Technorati Tags: Nanofibers or Nanotubes and Nano or Nanotechnology and nanoparticles or Nanotech and Nanopore or nanochemistry and nanoscale or nanowires and nanogenerators or nano test tubes and Biotechnology or aldehyde chemical group and nanostructures or Nanoscience

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World’s tiniest test tubes get teensiest corks, Filed under Research, Health, Sciences on Wednesday, May 10, 2006.

Rows of tiny nano test tubes rest on a mesh in this electron microscope photo, shot in October of last year and colorized for added clarity. Seeking to deliver drugs within the body,

University of Florida scientists have found a way to “cork” the tubes. The goal is to develop the ability to fill the teeny tubes with drugs and inject them into the body, where they will seek diseased or cancerous cells, uncork and spill their therapeutic contents in the right place. High Resolution Photo.

GAINESVILLE, Fla. — Now all they need is a really, really small corkscrew.

Like Lilliputian chemists, scientists have found a way to “cork” infinitesimally small nano test tubes. The goal is a better way to deliver drugs, for example, for cancer treatment. Scientists want to fill the teeny tubes with drugs and inject them into the body, where they will seek diseased or cancerous cells, uncork and spill their therapeutic contents in the right place.

“After making the nano test tubes, we saw the potential for them to be used for drug delivery vehicles, but because they are open at one end it would be like trying to ship wine in a bottle without a cork,” said University of Florida, chemistry professor Charles Martin. “You have to cork it, which is what we have accomplished.”

Martin is one of six University of Florida chemistry faculty members and graduate students who co-authored a paper about the research that appeared last month in the Journal of the American Chemical Society.

While chemotherapy works against many cancers, it can cause severe side effects such as nausea, temporary hair loss and blood disease. To make the chemo hit only the cancerous cells, Martin and scientists elsewhere have spent recent years experimenting with drug-carrying nanotubes or nanoparticles.

“Nano” stems from nanotechnology, the fast-growing science of making objects or devices that approach molecular dimensions. One nanometer equals one-billionth of a meter.

The approach makes sense for attacking diseased cells while bypassing healthy ones, but it also poses challenges. For one thing, the nanotubes must recognize their target, a problem scientists are attacking by tweaking their chemistry to make it respond to the unique chemistry of cancer cells. The tubes also must be biologically benign. Martin says a method for making nanotubes he pioneered, template synthesis, allows manufacturers to use biodegradable material, such as the polylactides that compose biodegradable sutures.

Additionally, the tubes also had to be closed at one end to form the classic test tube shape, a problem Martin and his group solved in research published in 2004.

To “cork” the test tubes in the latest research, the researchers applied an amino chemical group to the mouth of the tubes and an aldehyde chemical group to the corks. The two groups are complementary, so they bond with one another.

Billions of nanotubes could fit on a postage stamp. So, said Martin, “we don’t put individual caps in each nanotube the way corking machines do for bottles.”

Instead, the scientists immerse a small mesh that holds millions of amino-modified nanotubes, all precisely lined up in a grid pattern, into a solution imbued with millions of the corks. Brownian motion — what happens when minute particles immersed in a fluid move about randomly — takes care of the rest. The corks simply float around, then slip into the mouths of the tubes as they encounter them.

The diameter of the tubes is about 80 nanometers, or 80-billionths of a meter. Even though they are tiny, each tube can hold about 5 million drug molecules. “Each tube packs a real punch in terms of the number of drug molecules it can deliver,” Martin said.

Sang Bok Lee, an assistant professor of chemistry and biochemistry at the University of Maryland, works on similar research. He said scientists have proposed capping the tubes using chemical interactions between the drugs and the tubes. But that might not work because the tube could leak before it reaches its target.

“I strongly agree that Professor Martin’s proposed strategy will be one of the ideal solutions for the problem of controlling drug uptake and release,” he said in an e-mail.

The UF scientists aren’t there yet. There’s no easy way to unlock the amino chemical group from the aldehyde chemical group. So while Martin says there are some promising possibilities, he and his colleagues have their next job cut out for them: figuring out how to uncork the tubes. -30-

Credits: Writer, Aaron Hoover, ahoover@ufl.edu, (352) 392-0186, Source: Charles Martin, crmartin@chem.ufl.edu, (352) 392-8205

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