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
- (d) 1, 2, 3 and 4 ✓ UPSC's answer
Why the answer is (d)
• Carbon nanotubes (CNTs) are cylinders of graphene with huge surface area, strength and conductivity.
• Statement 1 is correct: functionalised CNTs carry drugs, vaccines and antigens across cell membranes for targeted delivery.
• Statement 2 is correct: CNT-based scaffolds have been engineered into artificial capillaries and vascular grafts for tissue repair.
• Statement 3 is correct: their electrical sensitivity makes CNTs ideal for biochemical and glucose sensors.
• Statement 4 is treated as correct in the official key: studies show CNTs can be degraded by enzymes such as myeloperoxidase in the body, though they are not readily biodegradable in the environment — a debatable point.
• Hence 1, 2, 3 and 4, option (d).
Why the other options are wrong
- (a) 1 and 2 only
- Statements 3 and 4 are also counted as correct.
- (b) 2, 3 and 4 only
- Statement 1 on drug delivery is also correct.
- (c) 1, 3 and 4 only
- Statement 2 on artificial capillaries is also correct.
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.