What is a nano carbon?

Natural carbon can exist in two very different types and is know to everyone: graphite and diamond. Three additional forms of carbon that were discovered between 1985 and 2004 have caused the current excitement among researchers about carbon nanomaterials – fullerenes, nanotubes, and graphene. 

See here for details:  https://www.quora.com/What-is-a-nano-carbon

What makes carbon nano tube gives such strength?

Carbon nano tubes are considered as one of the strongest material when mixed with a matrix material like epoxy and polymer to form nano composites. Their structural strength or load bearing capacity is even multiple times higher than structural steel if properly fabricated. The most important property which nanocomposites possess is their very high strength to weight ratio. Strength to weight ratio is a very important parameter in composite technology to rate composite on the basis of their structural properties. Also, depends on the stacking sequence, carbon nano tubes gives excellent structural properties in different-different arrangement of its layers in composites like unidirectional arrangement, bi-directional arrangement, skew arrangement etc.

 

Reference: https://www.quora.com/What-makes-carbon-nano-tube-gives-such-strength

What is the difference between nanomaterials and nanoparticles? What is a carbon nanotube considered as?

All nanoparticles are nanomaterials, but not all nanomaterials are nanoparticles.

Nanoparticles are particles within a nanometer size range. Typically this is in the 10 - 999nm range, with things at the lower end being large molecules or macromolecules (such as many proteins) and at the larger end becoming microparticles (1000 - 100,000 nanometers, or 1 - 100 micrometers / um).

Nanomaterials can have broad definitions. For instance, if you have knowledge of the packing structure of different atoms comprising some form of a metal alloy, you are gaining insight into the structure of the metal at the nanomaterials level.

Another example of nanomaterials that are not nanoparticles is transistors and most of your computer’s hardware. Each transistor is on the order of ~10 nanometers, but it is not a nanoparticle (someone may argue this point :) ).

Nanoparticles can be biological, such as those used for gene or drug delivery applications in FDA/clinical applications, or non-biological such as the titanium and zinc nanoparticles in some sunblocks. They can be made of metals, proteins, genes, ceramics, or any range of materials that are normally found in the world. However, they are constrained to being in a particle format within certain size ranges as opposed to being a more solid matrix with some form of nanostructure (nanomaterials).

You can, also, include nanoparticles within solid matrixes such as ceramics and buildings to modulate their properties.

Carbon nanotubes *can* be used to make nanoparticles. Nanoparticles can be spherical, oblong, tube-like, or any shape you can imagine. However, carbon nanotubes are very, very thin. Depending on whether they are single-, double- or multi-walled, their thickness can range from 2 - 9.5nm (Single, Double, MultiWall Carbon Nanotube Properties & Applications). An aggregate of carbon nanotubes or a 9.5nm x 50nm carbon nanotube would be considered a nanoparticle.

Reference: https://www.quora.com/What-is-the-difference-between-nanomaterials-and-nanoparticles-What-is-a-carbon-nanotube-considered-as

How are carbon nano tubes helpful in defense field?

Carbon nano tubes due to its excellent multi-directional properties basically related to mechanical and electrical engineering make it very popular for some of the most advanced technological applications in the field of aircrafts and defense industry.

In a typical aircraft, there may be thousands of complex parts and all of them need to work efficiently during the operation. So, it is very cumbersome process to inspect each and every thing before each flight as preflight inspection schedule. But, anyhow pilots have to do this. Here come the use of Carbon nano tube. Transparent carbon nano tubes are a way better solution in this regard.

Aircraft wings are also one of the complex parts to inspect because it has several moving parts which results in more number of joints and more possibility to be faulty frequently. So, proper inspection of them is also a vital factor. So, here also transparent carbon nano tubes are best solution not only for transparency but also for good material and structural properties needed for an aircraft wing.

Reference: https://www.quora.com/How-are-carbon-nano-tubes-helpful-in-defense-field

How are nanoparticles used in nanomedicine removed from the body?

Nanoparticles in medicine usually accumulate in one organ of the body or another except the brain(due to the blood-brain barrier). Even if the particles are encapsulated in a biocompatible polymer such as PEG, the only parameter affected is the blood stability time of the nanoparticles.

The most common organ of deposition is the liver and spleen, although the heart and lung tissue are major contenders also. Particles if size range 500-1000 nm tend to accumulate in the lungs and kidneys and the specific reaction to such particles depends on the metal composition and the encapsulating polymer. 

Particles of lower size range(10-200 nm) accumulate preferentially in the liver and spleen. Even if the accumulated particles are benign, saturation causes necrosis of tissue. I recently read about distribution of gold nanorods in mice. Saturation of nanorods in the liver caused necrosis of liver tissue after dosage of 0.3 micrograms over a period of four weeks.

While particles of higher size range are evacuated after a week of ingestion, the smaller particles are permanently trapped in the body tissue.

Reference: https://www.quora.com/How-are-nanoparticles-used-in-nanomedicine-removed-from-the-body

Which nanomaterial is used to prevent the WBC from taking gold nanoparticles as an antigen?

Gold nanoparticles are typically smaller than several hundred nanometers in size, comparable to large biological molecules such as enzymes, receptors, and antibodies. With the size of about one hundred to ten thousand times smaller than human cells, these nanoparticles can offer unprecedented interactions with biomolecules both on the surface of and inside the cells. Therefore silver nanoparticles can be used as they are antimicrobial in function thereby the white blood cells are prevented from taking au nanoparticles as an antigen.

Reference:https://www.quora.com/Which-nanomaterial-is-used-to-prevent-the-WBC-from-taking-gold-nanoparticles-as-an-antigen

Why are metal nanoparticles used more than polymer nanoparticles in biological (green) nanoparticles?

There are lots of reason for choosing metal over polymer nanoparticles. some of them are:-

1. Shape and size of metal nanoparticles can be easily controlled and synthesized
2. Some metal being inherently magnetic in nature can be used for targeted and controlled drug delivery application
3. Most of the metal intrinsically photoactive can be used in for photoactivated degradation of some specific cell which is not possible in a pure polymer
4. polymer has a large molecular weight and controlling for an application is difficult when compared to metal NPs.

Reference: https://www.quora.com/Why-are-metal-nanoparticles-used-more-than-polymer-nanoparticles-in-biological-green-nanoparticles