[Solved] With reference to carbon nanotubes, consider the following statements: 1. They can be used as carriers of drugs and antigens in the human body. 2. They can be made into artificial blood capillaries for an injured part of the human body. 3. They can be used in biochemical sensors. 4. Carbon nanotubes are biodegradable.

Q1. With reference to carbon nanotubes, consider the following statements:

1. They can be used as carriers of drugs and antigens in the human body.

2. They can be made into artificial blood capillaries for an injured part of the human body.

3. They can be used in biochemical sensors.

4. Carbon nanotubes are biodegradable.

Which of the statements are given above are correct?

a. 1 and 2 only

b. 2, 3 and 4 only

c. 1, 3 and 4 only

d. 1,2,3 and 4

Answer: c

What are carbon nanotubes?

· are cylindrical molecules that consist of rolled-up sheets of single-layer carbon atoms (graphene)

· Carbon nanotubes (CNTs) are characterized by unique chemical and biological properties. CNTs have a large surface area that allows them to attach a wide range of biological substances. In addition, CNTs are able to penetrate through cell membranes, capillaries, and accumulated in cells and tissues.

· Carbon nanotubes were once considered to be resistant to chemical damage due to their rigid and perfect chemical structure, which rendered them immune to biodegradation. However, enzymes like peroxidase were found to play an important role in the process of biodegradation of carbon nanotubes. Hence option 4 is correct.

Carbon nanotubes

Graphene (Strongest material)

· Single layer of carbon atoms.

· It is harder than diamond yet more elastic than rubber

· Tougher than steel yet lighter than aluminium.

· Lowest resistivity substance known at room temperature.

· High thermal stability.

· High elasticity.

· High electrical conductivity.

· Electron mobility is high at room temperature.

What are carbon nanotubes?

· are cylindrical molecules that consist of rolled-up sheets of single-layer carbon atoms (graphene)

Types

· They can be single-walled (SWCNT) with a diameter of less than 1 nanometer (nm)

· Multi-walled (MWCNT), consisting of several concentrically interlinked nanotubes, with diameters reaching more than 100 nm.

Properties

· Mechanical tensile strength can be 400 times that of steel;

· very light-weight

· Thermal conductivity is better than that of diamond;

· Highly chemically stable and resist virtually any chemical impact unless they are simultaneously exposed to high temperatures and oxygen – a property that makes them extremely resistant to corrosion;

· Hollow interior can be filled with various nanomaterials

Electrical properties

· The rolling-up direction of the graphene layers determines the electrical properties of the nanotubes

Application

· CNTs are well-suited for virtually any application requiring high strength, durability, electrical conductivity, thermal conductivity and lightweight properties compared to conventional materials.

· Currently, CNTs are mainly used as additives to synthetics.

· CNTs are commercially available as a powder, i.e. in a highly tangled-up and agglomerated form

· Carbon nanotubes can also be spun into fibers

· Sporting goods(bicycle frames, tennis rackets, hockey sticks, golf clubs and balls, skis, kayaks; sports arrows)

· Other-Textile, automotive etc

Biodegradable

· CNTs are extremely physically and chemically stable, and therefore may not be biodegradable.

· However, novel approaches for degrading CNTs have been developed.

· These methods, which use peroxidases, neutrophils, and macrophages have yielded some encouraging results