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 given above are correct?

[UPSC Civil Services Exam – 2020 Prelims]

(a) 1 and 2 only

(b) 2, 3 and 4 only

(c) 1, 3 and 4 only

(d) 1, 2, 3 and 4

Answer: (d)        

Explanation:

• Carbon nanotubes (CNTs) are cylindrical molecules composed of carbon atoms arranged in a hexagonal pattern. They can be formed by rolling up a single graphene sheet (SWCNTs) or multiple sheets (MWCNTs).
• CNTs were once believed to be chemically resistant, but enzymes like peroxidase have been found to facilitate their biodegradation, making option 4 correct.
• NASA has demonstrated the use of CNT arrays as biosensors, making option 3 correct.
• CNTs have a large surface area, enabling them to attach various biological substances and penetrate cell membranes, making them useful for biomedical applications such as artificial implants and drug delivery, hence making statements 1 and 2 correct.