Thursday, June 30, 2011

Nanotechnology: The Science of Over the Edge

Nanotechnology is the technology of manipulating matter at the scale between the every day world--the big, visible stuff--and the world of the quantum--the teeny, tiny. "A nanometer is about the width of a strand of DNA," says Discover magazine, July/August, 2010, issue. Nanometer, abbreviated nm, is a name derived from the Greek word for midget, nano. Each nanometer is only three to five atoms wide, 40,000 times smaller than the width of the human hair. Nanoparticles contain tens of thousands of atoms and straddle the world of Newton and the world of quantum mechanics.But nanotechnology is not new.

Human beings have used nanotechnology in sunscreen and ink-jet printers. But medieval stained glass nanotechnologists have probably created the most amazingly beautiful nano-tech products to date: stained glass colored with gold. The medieval art of making stained glass reached its peak in the years between 1100 and 1500.

Most of what we know about medieval stained glass was recorded by a monk who called himself, Theophilus, in his book titled On Diverse Arts. He wrote that powdered metals such gold, copper and silver were used to color molten glass. Gold particles were simple spheres about 25 nanometers in diameter. At such a small size, gold no longer glitters. The beautiful red of stained glass was created when gold chloride, a compound of gold and chlorine, which was prepared by passing chlorine gas over gold powder, was mixed with molten glass turning gold into tiny spheres that sloshed in unison and absorbed blue and yellow light while allowing the longer wavelength, red, to shine in a rich ruby hue. To achieve a bright yellow hue, nanoparticles of silver were used. Change the size of the gold nanoparticles and a different color is achieved. With today's more sophisticated tools, nanotechnologists can make particles of many different shapes and sizes. Larger gold spheres create green and orange hues. Small silver ones make blue. Changing the size and shape of a gold or silver nanoparticle can produce every color of the spectrum.

In a New York Times article, titled, "Tiny is Beautiful: Translating 'Nano' Into Practical," Dr. Chad A. Mirkin, a director of Northwestern University's Institute for Nanotechnology, said "everything, regardless of what it is, has new properties" because of the changes made in quantum mechanical and thermodynamic properties at the nanometer scale. He added, this is "where a lot of the scientific interest is." Dr. A. Paul Alivisatos, a professor of chemistry, University of California, Berkeley, stated, "instead of changing composition, you can change size."  Dr. Alivisatos, founding scientist of Quantum Dot Corporation, works with nanoparticles, called "quantum dots" made of semiconductors and gallium arsenide. The size and shape of the quantum dots can be manipulated to fluoresce specific colors. In a medical application, current dyes used to light up proteins fade quickly, but quantum dots could allow tracking of biological reactions in living cells for days.

Kenneth Chang, author of the New York Times article mentioned above, wrote, "Other applications of nanoparticles take advantage of the fact that more surface area is exposed when material is broken down to smaller sizes. For magnetic nanoparticles, the lack of blemishes produces magnetic fields remarkably strong considering the size of the particles. Nanoparticles are also so small that in most of them, the atoms line up in perfect crystals without a single blemish"

Dr. David F. Kelley, a professor at the University of California, Merced, is researching the chemical, optical and electronic properties of semiconductor nanoparticles and electron transfer reactions involving inorganic dyes. He's interested in nanoparticles because of their possible applications in regenerative photocells, photocatalysis and in electroluminescent devices. He seeks to come to understand size-dependent spectroscopy and photophysics on a nanoparticle level. This research may be applied to create solar cells that would allow electrons to hop more easily between particles due to the flawless structure possible on a nanoparticle scale.

Dr. Yi Lu, a chemistry professor at the University of Illinois. He uses DNA as a building block for nanoscale components. His primary areas of research include: DNA mediated assembly and growth of nanoparticles, directed nanoscale self-assembly on a DNA scaffold and reversible cell-specific drug delivery with Apatamer-functional lipsomes. He takes advantage of the color changes that occur at the nanoparticle level to create a test for hazardous levels of lead. DNA molecules attached to gold nanoparticles, tangle with other specially designed pieces of DNA to make clumps that appear blue. Lead causes the connecting DNA to fall apart cutting loose the gold nanoparticles and changing the color to red.

Dr. Mirkin uses gold nanoparticles as a connecting point to build disease sensors. He attaches a gold particle to an antibody and adds snippets of DNA that act as bar codes. This approach has produced a test for Alzheimer's disease by measuring minuscule amounts of a protein in spinal fluid associated with the disease. His company, Nanosphere Inc. is working to bring this technology to market.

Dr. Naomi J. Halas, a professor of electrical and computer engineering at Rice University, has invented a type of particle she's dubbed "nanoshells," which are hollow gold or silver spheres wrapped around a filling of silica.These may be used to treat cancer by applying the ability of nanoparticle-sized hollow shape to increase gold's efficiency in absorbing light energy. When these nanoshells are injected into a tumor and infrared light is shined on them, they heat up and kill the tumor. Researchers in Dr. Halas's lab have demonstrated nanoshells unique ability by inserting nanoshells into uncooked chicken parts and then shining a near infrared laser at the chicken. Since water does not absorb much infrared light, the light passes through most of the meat without having any effect, but the nanoshells heat up, cook the chicken, then start smoking and catch on fire. In actual treatment, lower intensity of light would be used to avoid cooking the patient. See also Dr. Halas's associate's site: Nanospectra and Nanomedicine Targets Cancer.

Shrinking medication to nanoparticle size will improve effectiveness. Altair Nanotechnologies of Reno has developed a possible drug for kidney patients: nanoparticles of lanthanum dioxycarbonate. This chemical binds to phosphate which builds up in failing kidneys and prevents it from entering tissue. A small amount with each meal can have a huge beneficial effect.

Discover magazine article by Nayanah Siva titled Smart Bandages Nurse Your Wounds reported Toby Jenkins and colleagues of the University of Bath in England, are working on self-medicating bandages that promise to keep serious wounds free of infection using nanocapsules that release antimicrobials when bacterial toxins appear in a wound. Harmful bacteria will also cause the dressing to change color alerting care takers that a problem exists. This could be especially helpful for burn victims. Nearly 50% of all burn-related deaths are caused by infection. This new technology will allow fewer bandages to be used which will reduce scarring and speed healing.

Siva writes, "Cell biologist Paul Durham and his team from Missouri State University are working on a multitasking bandage layered with antifungal, antibacterial, and anti-inflammatory agents for use on a variety of wounds, including deep cuts and punctures. In the initial prototype, a battery-powered time-release mechanism will dispense the medications, but ultimately the researchers hope to incorporate chemical sensors that will trigger drug release in response to changes in the wound."

In a January, 2000, issue, Wendy Marston reported in Discover online Future Tech article sub titled: Can we interest you in a suit that banishes dirt, sweat, and germs, sir? nano-tech mills could completely change how clothing is made. David Forrest, president of the Institute for Molecular Manufacturing, says that nano-mills will create custom fabrics assembled atom by atom using contraptions the size of photocopy machines. "Raw materials such as nitrogen, carbon and hydrogen will be put into a desk-size unit which will rearrange the elements and control the trajectories of all the molecules" in order to fabricate the material. He also plans to incorporate sensors to detect rips and tears which will alert parmecium-size robotic crews to fix the holes by means of atomic manipulation. Gain a few pounds? Electro-mechanically controlled molecules in the fibers could change the shape of a garment with the touch of a button. Nano-manufactured clothing might even launder itself using nano-sized, micro-maids to remove dirt to a collection area where it will be picked up. "Robotic devices similar to mites could periodically scour the fabric surfaces," says Forrest. Mico-maids would also handle the rinse cycle. "It may be extraordinarily difficult to do this," he says, "but there's no scientific barrier."

Nanobots that clean spaceships, nano-drug-delivery systems and nano-manufactured textiles, clothing and facsimile copies of documents identical to the originals from the molecular level up are features of the Over the Edge science fiction series. In one scene a character uses a nano-heart attack to assassinate a criminal. Nanobots clean spaceships and check them for hazardous particles or micro-organisms and out-of-place insects, threads or buttons and report their findings to ship's captains.

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