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 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 ✓ UPSC's answer
- (d) 1, 2, 3 and 4
Why the answer is (c)
• Carbon nanotubes (CNTs) are rolled sheets of graphene with very large surface area, high strength and electrical conductivity.
• Statement 1 is correct: functionalised CNTs are used as carriers of drugs and antigens (vaccine delivery) in the body.
• Statement 3 is correct: their electrical sensitivity makes CNTs useful in biochemical sensors such as glucose and DNA sensors.
• Statement 4 is accepted as correct: studies (for example, 2010 work on the enzyme myeloperoxidase) showed CNTs can be broken down by enzymes in the body.
• Statement 2 is not accepted: CNTs are studied as scaffolds for tissue engineering, but they cannot be 'made into artificial blood capillaries' for an injured part of the body.
• UPSC's official answer key gives (c).
• Hence 1, 3 and 4 only, option (c).
Why the other options are wrong
- (a) 1 and 2 only
- Statement 2 is not accepted, and statements 3 and 4 are left out.
- (b) 2, 3 and 4 only
- Statement 2 is not accepted, and drug delivery (1) is left out.
- (d) 1, 2, 3 and 4
- Statement 2 on artificial capillaries is not accepted by the official key.
Asked in the GS Paper I of the UPSC Civil Services Preliminary Examination 2020, held on 4 October 2020. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.