The NanoWorld

Researched by: Stephen Chow, 3P304

Nano World

It is the sphere of influence of nanotechnology.

Nanotechnology is the study of controlling of matter or an atomic or molecular scale.

Nanotechnology is very diverse, ranging from extensions of conventional device physics to completely new approaches based upon molecular self-assembly, from developing new materials with dimensions on the nanoscale to investigating whether we can directly control matter on the atomic scale.

Nano Particle

In nanotechnology, a particle is defined as a small object that behaves as a whole unit in terms of its transport and properties.

Nanoparticles may or may not exhibit size-related properties that differ significantly from those observed in fine particles or bulk materials.

Nano Particles

It is further classified according to size: in terms of diameter, fine particles cover a range between 100 and 2500 nanometers, while ultrafine particles, on the other hand, are sized between 1 and 100 nanometers.

If a nano particle is scaled to the size of a ping-pong ball, a basketball would be scaled to about the size of Singapore!

Gold

All that glitters is not gold, goes the old adage.

Gold

Gold is known as a shiny, yellow noble metal that does not tarnish, has a face centred cubic structure, is non-magnetic and melts at 1336 K. However, a small sample of the same gold is quite different, providing it is tiny enough

Nano Gold [Properties]

10 nm particles absorb green light and thus appear red. The melting temperature decreases dramatically as the size goes down. Moreover, gold ceases to be noble, and 2-3 nm nanoparticles are excellent catalysts which also exhibit considerable magnetism.

At this size they are still metallic, but smaller ones turn into insulators. Their equilibrium structure changes to icosahedral symmetry, or they are even hollow or planar, depending on size.

Nano Gold [Properties] ||

More interestingly, as the gold particle size is decreased, there are many intriguing phenomena.

For example, substantional bond contraction occurs to the outermost two atomic shells, being independence of support type; the Debye-Waller factor increases associated with low compressibility; the energy levels go to deeper, and the catalytic ability increases by several folds.

Nano Gold [Explanation]

These intriguing properties have partially, and might be reconciled by the recently developed bond-order-length-strength (BOLS) correlation mechanism which indicates that the broken bond induced local strain (surface bond contractrtion) and quantum trapping and the associated densification of charge and energy in the surface skin are responsible for the size induced behavior.

Nano Gold [Explanation] ||

The shorter and stronger bonds in the surface skin not only lower the energy levels of the electrons but also enhance the elecronegartivity and hence make the less-coordinated atoms are more “hunger” to gain electrons from the specimens demonstrating the highly regarded catalytic effect as observed.

Further exploration is in well progress.

Nano Gold Exploration

It is also possible to tailor the properties of the nanoparticles assemblies by varying the size and elemental composition of the particles.

By heating nanoparticles arrays at different rates, they can also introduce instability into the structures, since the smaller nanoparticles have a tendency to melt first. They have succeeded in causing a string of nanoparticles to melt into a nanowire that is 10 times thinner than any wire made using the standard microelectronic process called electron beam lithography.

Nano Gold Exploration ||

Scientists in Japan discovered 10 years ago that gold displays fantastic catalytic abilities when it is shrunk to 3 to 5 nm in size. If the gold particles are any bigger or smaller than this, the element resumes its inertness.

Nano Gold Exploration ||

One such reaction is the conversion of carbon-monoxide (CO) to carbon-dioxide (CO2). Nanogold catalyzes this at room temperature and with 100-percent efficiency. A potential application is to aid firefighters, who now wear protective masks containing copper-manganese-oxide. That material's effectiveness at getting rid of CO, however, lasts only 15 minutes, while nanogold protects for several hours.

Venturing beyond Nano Gold

What are the uses of Nano-Particles in life?

Nanoparticles in consumer products

Nanoparticles are now being used in the manufacture of scratchproof eyeglasses, crack- resistant paints, anti-graffiti coatings for walls, transparent sunscreens, stain-repellent fabrics, self-cleaning windows and ceramic coatings for solar cells.

Nanoparticles can contribute to stronger, lighter, cleaner and “smarter” surfaces and systems.

Nanoparticles in consumer products ||

Nanoparticles of titanium oxide used in sunscreens, for example, have the same chemical composition as the larger white titanium oxide particles used in conventional products for decades, but nanoscale titanium oxide is transparent.

Antimony - tin oxide provides another example since nanoparticles of this oxide are incorporated into a coating to provide scratch- resistance and offer transparent protection from ultra-violet radiation, not seen with larger size particles.

Nano particles in Medicine

The development of nanotechnologies for nanomedical applications has become a priority of the National Institutes of Health (NIH).

Between 2004 and 2006, the NIH established a network of eight Nanomedicine Development Centers, as part of the NIH Nanomedicine Roadmap Initiative. In 2005, The National Cancer Institute (NCI) committed 144.3 million over 5 years for its “Alliance for Nanotechnology in Cancer” program which funds seven Centres of Excellence for Cancer Nanotechnology (Kim, 2007).

The funding supports various research projects in areas of diagnostics, devices, biosensors, microfluidics and therapeutics.

Nano particles in Medicine ||

Among the long term objectives of the NIH initiative are goals such as being able to use nanoparticles to seek out cancer cells before tumors grow, remove and/ or replace “broken” parts of cells or cell mechanisms with miniature, molecular-sized biological “machines”, and use similar “machines” as pumps or robots to deliver medicines when and where needed within the body.

Nanoparticle in Gene Therapy

Nanoparticles Deliver Gene Therapy, Killing Tumors

March 26, 2009 (PhysOrg.com)

Given that cancer is ultimately a genetic disease, it has long been the hope of researchers to use gene therapy to attack tumors where they might be most susceptible.

Those prospects have taken a significant step forward with the report that a trans-European research team has developed a nanoparticle that transports antitumor genes selectively to cancer cells. The technique, which leaves healthy cells unaffected, could offer hope to people with difficult-to-treat cancers.

Although it has so far been tested only in mice, the researchers hope for human trials in 2 years.

Nanoparticles in Cars

Nanoparticles can improve adhesion of tyres to the road, reducing the stopping distance in wet conditions. In addition, the stiffness of the car body can also be improved by use of nanoparticle-strengthened steels. Moreover, ultra-thin transparent coatings can be applied to displays or panes to avoid glare or condensation, and in the future it may be possible to produce transparent car body parts to improve all-round vision.

Nanoparticles in Solar Cells

Inexpensive thin-film solar cells aren't as efficient as conventional solar cells, but a new coating that incorporates nanoscale metallic particles could help.

Nanoparticles in Solar Cells ||

Solar antenna: The square at the center is an array of test solar cells being used to evaluate a coating that contains metallic nano antennas tuned to the solar spectrum.

Credit: Brongersma lab, Stanford

Nanoparticles in Solar Cells |||

Elaboration: Nanoscale metallic particles take incoming light and

redirect it along the plane of the solar cell. As a result, each photon takes a longer path through the material, increasing its chances of dislodging an electron before it can reflect back out of the cell.

The nanoparticles also increase light absorption by creating strong local electric fields.

Nanoparticles in food

Researchers are working towards the possible use of nanoparticles for food safety. Byron Brehem-Stecher, an assistant professor in food science and human nutrition is working towards the possible use of silver nanoparticles for improving the safety of food supply. Although nanoparticles can not be used as food ingredients, however these can be used for developing food related applications.

Nanoparticles in food ||

The immediate possible food related applications seems to be microbe - resistant fabrics and non - biofouling surfaces. According to Byran brehem - techer, the study will lead to understand the affect of silver nanoparticle on microbial structure of the material.

The study will also enhance the understanding abilities of silver nanoparticles to interact with microbial cells.

Nanoparticles in food |||

Byron Brehem - Stecher prepared silver nanoparticles by vaporizing metallic silver in presence of an inert gas and thereafter controlled condensing the particles in such a way to get the nanoparticles below 100 nm size. Brehem - Stecher claims that the study although is at primary stage, some very interesting clues has already been discovered about the nanosilver as an antimicrobial.

Thank you!