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 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

Ans: c

Explanation:

Carbon nanotubes (CNTs) are carbon-based nanomaterials with a tubular structure composed of rolled up graphene sheets. These tubes can consist of single or multiple graphene layers. CNTs share the same π-bond character as graphene, allowing electrons to be delocalized throughout the structure.

Carbon Nanotubes Uses and Applications

• Automotive parts
• Electronics: circuitry, batteries, supercapacitors
• Photovoltaic technology – including solar panels, LEDs, sensors, transistors, field emitting devices, fuel cells, actuators (devices that power physical movement)
• Absorbents
• Catalysts
• Biomedicine: drug delivery, biosensing, bioimaging, nanorobotics, gene therapy and tissue regeneration (Biosensors are devices used to detect the presence or concentration of a biological analyte, such as a biomolecule, a biological structure or a microorganism.)
• Agriculture: bioremediation, water purification
• Carbon nanotubes can be added to a material or substance (nanocomposite) to enhance strength. This is useful, for example, in the manufacture of sportswear, or materials used in the deflection of projectiles including bullet-proof vests.

The greatest concern about the risk of CNTs is related to their unique physicochemical nature: specifically, these materials are extremely stable and difficult to degrade. Historically, it was widely accepted that CNTs could only be chemically degraded by strong oxidants or heat treatment in oxygen .In 2008, however, a pioneering study showed for the first time that CNTs could be biodegraded through enzymatic oxidation by horseradish peroxidase (HRP). 

Capillary blood vessels are minute blood vessels, 5–10 μm in diameter, carrying blood from arterioles to venules.The capillaries are very thin and form a fine network called a capillary bed.

Limitations with carbon nanotubes 

An important discovery has been made about the safety issues of using carbon nanotubes as biomaterials which come into contact with blood. When blood comes into contact with foreign surfaces the blood’s platelets are activated which in turn leads to blood clots being formed. They found that the carbon nanotubes did actually stimulate blood platelet activation, subsequently leading to serious and devastating blood clotting.

This can be catastrophic in clinical settings.

Hence, option c is correct.

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