UPSC CSE Prelims
Nanotechnology Previous Year Questions (PYQs)

Detailed Explanation:

Answer: Option 1 — 1 only

Carbon fibres are extensively used in manufacturing components for automobiles and aircraft due to their exceptional strength-to-weight ratio, high stiffness, and lightweight properties. Statement 1 is correct as these materials are crucial in aerospace and automotive industries for reducing weight and improving fuel efficiency.

✅ Statement 1 – Correct: Carbon fibres are indeed used in manufacturing automobile and aircraft components due to their superior mechanical properties and lightweight nature.

❌ Statement 2 – Incorrect: Carbon fibres can be recycled through various methods including mechanical recycling (breaking down into smaller pieces), chemical recycling (dissolving resin to extract fibres), and thermal recycling (pyrolysis to recover fibres), though the technology is still evolving.

📝 Short Notes: Carbon Fibres

• Composition: Made from organic polymers consisting of long strings of carbon atoms bonded together in crystalline alignment
• Key Properties: High tensile strength, low weight (5 times lighter than steel), high stiffness, high temperature tolerance, low thermal expansion, and chemical resistance
• Manufacturing Process: Produced through carbonization of precursor materials like polyacrylonitrile (PAN), pitch, or rayon at high temperatures (1000-3000°C)
• Applications: Aerospace (aircraft fuselage, wings), automotive (racing cars, luxury vehicles), sports equipment (bicycles, tennis rackets), wind turbine blades, and medical devices
• Recycling Methods: Mechanical (chopping/milling), thermal/pyrolysis (burning off resin at 450-700°C), chemical (solvolysis using solvents), and electrochemical processes
• Challenges: High production cost, brittleness (low impact resistance), difficulty in recycling compared to metals, and specialized manufacturing requirements
• Environmental Consideration: While recyclability was limited earlier, modern recycling technologies are making carbon fibre composites more sustainable with recovered fibres retaining 90-95% of original properties

Detailed Explanation:

Answer: Option 4 — 2 and 3

This question tests understanding of nanoparticles, their natural occurrence, applications, and potential safety concerns. Statement 1 is incorrect as nanoparticles occur naturally through various processes, while statements 2 and 3 are correct regarding their use in cosmetics and potential environmental risks.

❌ Statement 1 – Incorrect: Nanoparticles exist naturally in the environment through volcanic eruptions, forest fires, ocean spray, and biological processes (e.g., viruses, protein complexes).

✅ Statement 2 – Correct: Nanoparticles of metallic oxides like zinc oxide (ZnO) and titanium dioxide (TiO₂) are commonly used in sunscreens and cosmetics for UV protection and improved texture.

✅ Statement 3 – Correct: Many nanoparticles from commercial products can enter the environment and may pose health risks due to their ability to penetrate biological barriers and accumulate in organs.

📝 Short Notes: Nanoparticles

• Definition: Particles with at least one dimension between 1-100 nanometers (nm)
• Natural Sources: Volcanic ash, sea spray, forest fires, mineral weathering, and biological entities (viruses, ferritin)
• Cosmetic Applications: Zinc oxide and titanium dioxide nanoparticles in sunscreens provide broad-spectrum UV protection without visible white residue
• Other Applications: Drug delivery, electronics, catalysis, water purification, antibacterial coatings
• Safety Concerns: High surface area-to-volume ratio allows interaction with biological systems; can cross blood-brain barrier and cell membranes; potential for bioaccumulation
• Environmental Impact: Persistence in environment, toxicity to aquatic organisms, unknown long-term effects on ecosystems
• Regulation: Many countries are developing specific guidelines for nanomaterial safety assessment in consumer products

Detailed Explanation:

Answer: Option 3 — 1, 3 and 4 only

Carbon nanotubes (CNTs) are cylindrical nanostructures with unique properties that make them suitable for biomedical applications including drug delivery, biosensing, and under certain conditions, biodegradation. Statement 2 is incorrect as CNTs cannot be reliably made into functional artificial blood capillaries—this application remains experimental and lacks validated clinical use.

✅ Statement 1 – Correct: CNTs can be functionalized with drugs and antigens, making them effective carriers for targeted delivery in the human body due to their ability to cross biological membranes.

❌ Statement 2 – Incorrect: While CNTs have been explored in tissue engineering scaffolds, they cannot be made into functional artificial blood capillaries as these require precise biological compatibility, flexibility, and permeability that CNTs alone cannot replicate.

✅ Statement 3 – Correct: CNTs possess high surface-to-volume ratio and unique electrical properties, making them ideal for biochemical sensors that detect biomolecules like glucose, proteins, and DNA with high sensitivity.

✅ Statement 4 – Correct: Research has shown that CNTs can be biodegraded by oxidative enzymes such as myeloperoxidase (MPO) found in human neutrophils, though biodegradability depends on CNT type, structure, and surface functionalization.

📝 Short Notes: Carbon Nanotubes

• Structure: Cylindrical nanostructures composed of rolled-up sheets of graphene, with diameters in nanometers and lengths up to micrometers.
• Types: Single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs).
• Properties: Exceptional mechanical strength, high electrical and thermal conductivity, high surface area, and ability to be functionalized.
• Biomedical Applications: Drug delivery systems, gene therapy carriers, biosensors, tissue engineering scaffolds, and imaging contrast agents.
• Drug Delivery: Can be functionalized to carry therapeutic agents and target specific cells, improving drug efficacy and reducing side effects.
• Biosensors: Used in electrochemical and optical sensors for detecting glucose, cholesterol, DNA, proteins, and pathogens with high sensitivity.
• Biodegradability Debate: Some studies show enzymatic degradation by peroxidases, but biodegradability varies with CNT structure, functionalization, and environmental conditions; persistence in biological systems remains a concern.
• Challenges: Potential toxicity, biocompatibility issues, aggregation in biological fluids, and lack of standardized methods for large-scale production and functionalization.

Detailed Explanation:

✅ Statement 1 – Correct: Nanoparticles enable targeted drug delivery by carrying drugs directly to diseased cells, minimizing side effects and enhancing treatment efficacy.

✅ Statement 2 – Correct: Nanocarriers deliver genetic material (DNA/RNA) into specific cells, making nanotechnology crucial for gene therapy to treat genetic disorders.