19. Science and Technology Notes 08

Elaborate Notes

Introduction to Nanotechnology

Nanotechnology is the manipulation of matter on an atomic and molecular scale. Generally, it deals with structures sized between 1 to 100 nanometers in at least one dimension and involves developing materials or devices possessing at least one dimension within that size. The concept was first discussed in a 1959 lecture titled “There’s Plenty of Room at the Bottom” by physicist Richard Feynman, who envisioned the direct manipulation of atoms. The term “nanotechnology” was coined in 1974 by Norio Taniguchi of the Tokyo University of Science. At the nanoscale, materials exhibit unique physicochemical properties—such as increased surface area to volume ratio and quantum effects—that differ significantly from their macroscale counterparts.

The Uniqueness of Nanotechnology

• Biology at the Nanoscale: Most biological processes occur at the nanoscale. For instance, Haemoglobin, the protein responsible for oxygen transport, has a diameter of approximately 5 nm. A DNA molecule’s double helix has a diameter of about 2 nm. Viruses, cellular organelles like ribosomes, and protein channels all operate within this size range. This fundamental overlap allows nanotechnology to interface directly with biological systems, leading to innovations in medicine. Researchers like Robert Langer (MIT) have pioneered the use of polymer nanoparticles for drug delivery, demonstrating how nano-constructs can mimic biological carriers to target specific cells or tissues.
• Self-Assembly: This is a process where components (atoms, molecules, or even larger structures) spontaneously organize into ordered structures or patterns without external guidance. This phenomenon is driven by thermodynamic principles and local interactions between the components, such as van der Waals forces, hydrogen bonding, and electrostatic interactions. In nature, self-assembly is ubiquitous, seen in the formation of lipid bilayers for cell membranes and the folding of proteins into their functional shapes. In nanotechnology, scientists like George M. Whitesides (Harvard University) have harnessed this principle to create complex nanostructures for electronics and photonics, representing a cornerstone of the “bottom-up” manufacturing approach.

Nanomanufacturing Approaches

The fabrication of nanomaterials is broadly categorized into two distinct approaches:

• Top-down Approach: This approach involves starting with a larger piece of bulk material and carving or etching it down to the desired nanoscale dimensions.
  • Methodology: Techniques include photolithography (used extensively in the semiconductor industry), electron beam lithography, and mechanical milling.
  • Advantages: It is a relatively simpler, cheaper, and more established method for mass production.
  • Disadvantages: The process can be wasteful, as excess material is removed. More importantly, it often introduces surface imperfections and defects (e.g., crystal lattice damage), which can compromise the material’s properties. There is limited control over the surface characteristics and atomic-level precision.
• Bottom-up Approach: This approach involves building nanomaterials from the atomic or molecular level upwards, assembling them piece by piece.
  • Methodology: Techniques include chemical vapor deposition (CVD), molecular beam epitaxy (MBE), and colloidal synthesis for quantum dots. This approach is akin to how nature builds structures.
  • Advantages: It offers unparalleled precision, allowing for the creation of defect-free structures with finely controlled surface characteristics. It minimizes material wastage.
  • Disadvantages: It is often more complex, time-consuming, and expensive, making large-scale production a significant challenge.

Dimensionality of Nanomaterials

Nanomaterials are classified based on the number of dimensions that are not confined to the nanoscale (1-100 nm).

• Zero-dimensional (0D): All three dimensions are at the nanoscale. The material is confined in all directions.
  • Example: Quantum Dots (QDs), which are semiconductor nanocrystals. Their electronic and optical properties are heavily dependent on their size due to a phenomenon known as quantum confinement. They were discovered by Louis E. Brus at Bell Labs in the early 1980s.
• One-dimensional (1D): Two dimensions are at the nanoscale, while the third is larger, creating a needle-like or tube-like structure.
  • Example: Nanotubes, nanowires, and nanofibers. Carbon Nanotubes (CNTs), discovered by Sumio Iijima in 1991, are a prime example. Electrons are confined laterally but can move freely along the length of the tube.
• Two-dimensional (2D): Only one dimension is at the nanoscale, resulting in a sheet-like structure.
  • Example: Thin films, nanocoatings, and graphene. Graphene is a single atomic layer of carbon atoms arranged in a honeycomb lattice. Its isolation by Andre Geim and Konstantin Novoselov in 2004 (Nobel Prize in Physics, 2010) opened up new frontiers in materials science.
• Three-dimensional (3D): These are bulk materials that do not have any dimension confined to the nanoscale but possess a nanostructured architecture.
  • Example: Polycrystals with nanoscale grains, nanocomposites, and nanoporous materials. Nanocrystalline copper, for example, is significantly stronger and harder than conventional copper due to the high density of grain boundaries that impede dislocation movement.

Applications of Nanotechnology

• Daily Life Applications:
  • Textiles: Silver nanoparticles are embedded into fabrics to provide antimicrobial properties, inhibiting bacterial growth and odor. Nanoscale coatings create “self-cleaning” textiles that are hydrophobic (water-repellent) and oleophobic (oil-repellent).
  • Coatings: Nanoscale films of materials like titanium dioxide (TiO₂) and silicon dioxide (SiO₂) are used on surfaces like eyeglasses and smartphone screens to make them anti-reflective, scratch-resistant, and easy to clean.
  • Automotive: Carbon fiber-reinforced polymer (CFRP) nanocomposites are used to build lighter and stronger automotive parts, leading to improved fuel efficiency.
  • Cosmetics: Nanoparticles of zinc oxide (ZnO) and titanium dioxide (TiO₂) are used in sunscreens as they provide broad-spectrum UV protection without leaving a white residue on the skin.
• Applications in Healthcare:
  • Cancer Treatment: Gold nanoshells or nanorods can be engineered to accumulate in tumors. When exposed to near-infrared light, they heat up and destroy the cancerous cells selectively (photothermal therapy), minimizing damage to healthy tissue.
  • Targeted Drug Delivery: Nanoparticles can be loaded with drugs and functionalized with ligands (e.g., antibodies) that bind to specific receptors on diseased cells. This allows for direct delivery of medication to the target site, increasing efficacy and reducing systemic side effects. This is particularly promising for crossing the blood-brain barrier to treat neurological disorders.
  • Gene Editing: Nanoparticles are being developed as non-viral vectors to deliver CRISPR-Cas9 components into cells for gene editing. This approach can be safer and more efficient than using modified viruses.
  • Vaccines: Lipid nanoparticles (LNPs) were a critical component in the mRNA vaccines for COVID-19 (e.g., Pfizer-BioNTech, Moderna), encapsulating and protecting the fragile mRNA and facilitating its entry into human cells.
  • Antimicrobial Resistance (AMR): Nanomaterials like silver nanoparticles and quantum dots have demonstrated potent antimicrobial activity. They can disrupt bacterial cell membranes or generate reactive oxygen species (ROS) to kill bacteria, including strains that have become resistant to conventional antibiotics.
• Applications in Electronics:
  • Displays: Quantum dots are used in QLED televisions. When hit by a blue backlight, these dots emit light of a very specific color determined by their size, resulting in a wider color gamut, higher brightness, and better energy efficiency compared to traditional LCDs. Flexible displays use organic light-emitting diodes (OLEDs) on flexible nanoparticle-based substrates.
  • Transistors: As silicon-based transistors approach their physical size limits (as per Moore’s Law), researchers are exploring nanomaterials like carbon nanotubes and graphene to build next-generation field-effect transistors (FETs) that are smaller, faster, and more energy-efficient.
• Applications in Environment:
  • Water Filtration: Nanomembranes, such as those made from graphene oxide, have nano-sized pores that can effectively filter out contaminants, salts, bacteria, and viruses from water through processes like reverse osmosis, requiring less pressure and energy than conventional membranes.
  • Pollution Control: Nanocatalysts are used in catalytic converters in automobiles and industrial smokestacks to more efficiently convert toxic pollutants (like NOx and CO) into harmless substances.
  • Oil Spills: Researchers have developed nano-sponges and aerogels that are hydrophobic (repel water) and oleophilic (absorb oil). These can selectively soak up oil from water bodies, making cleanup operations more effective.

Carbon Nanotubes (CNTs)

• Structure: CNTs are allotropes of carbon with a cylindrical nanostructure. They are essentially rolled-up sheets of graphene. They can be Single-Walled Carbon Nanotubes (SWCNTs) or Multi-Walled Carbon Nanotubes (MWCNTs). The way the graphene sheet is rolled (its chirality) determines the CNT’s electrical properties.
• Properties:
  • Mechanical: They are among the strongest and stiffest materials yet discovered in terms of tensile strength and elastic modulus.
  • Electrical: Depending on their chirality, they can act as metallic conductors or semiconductors, making them highly versatile for electronics.
  • Thermal: They are excellent thermal conductors.
• Applications: Their properties make them useful in composites to enhance strength (e.g., in bicycle frames, wind turbine blades), as conductive films in touchscreens, in advanced batteries (e.g., lithium-ion), for hydrogen storage, and as tips for scanning probe microscopes.

Quantum Dots (QDs)

• Properties: QDs are semiconductor nanocrystals whose small size (typically 2-10 nm) leads to quantum mechanical properties. Their key feature is quantum confinement, which causes their optical and electronic properties to be size-dependent. Smaller dots emit higher-energy light (blue/green), while larger dots emit lower-energy light (orange/red). This tunability is a major advantage.
• Applications:
  • Displays: Used in QLED TVs for superior color reproduction.
  • Medical Imaging: They can be used as fluorescent probes for cellular imaging and tracking biological processes, as they are brighter and more photostable than traditional organic dyes.
  • Solar Cells: Their ability to absorb a broad spectrum of light can be used to improve the efficiency of photovoltaic cells.
  • Quantum Computing: QDs are being explored as a basis for qubits, the fundamental units of quantum information.

Nanotechnology in India

• National Mission on Nano Science and Technology (Nano Mission):
  • Launched in 2007 by the Department of Science and Technology (DST).
  • It is an umbrella program to foster R&D, infrastructure development, human resource development, and international collaboration in nanotechnology.
  • Phases: The first phase was from 2007-2012, and subsequent phases have continued its work.
  • Objectives: To promote basic research, establish centers of excellence (e.g., at IISc Bangalore, IIT Bombay), encourage private sector participation, and apply nanotechnology to solve national challenges in areas like water, health, and energy.
• Ministry of Electronics and Information Technology (MeitY) Initiative:
  • MeitY has a Nanotechnology Initiative Division focused on developing indigenous nano-electronics products and building R&D capacity. It supports institutions like IISc Bangalore and IIT Bombay to create a fabrication ecosystem for nano-devices, contributing to the ‘Make in India’ and ‘Atmanirbhar Bharat’ initiatives.
• Nano Urea:
  • Developed by the Indian Farmers Fertiliser Cooperative Limited (IFFCO).
  • It is a liquid fertilizer where urea is encapsulated in nanoparticles. A 500ml bottle of nano urea can replace a 45kg bag of conventional urea.
  • Mechanism: The nanoparticles have a higher surface area and are readily absorbed by the plant’s stomata, leading to a much higher Nitrogen Use Efficiency (NUE) of over 80% compared to ~30-40% for conventional urea.
  • Benefits: Reduces overall fertilizer consumption, lowers the government’s subsidy burden, and mitigates environmental pollution (e.g., soil degradation, water contamination, and nitrous oxide emissions).

Prelims Pointers

• Nanoscale Range: 1 to 100 nanometers (nm).
• Conceptual Founder: Richard Feynman’s 1959 speech, “There’s Plenty of Room at the Bottom”.
• Term Coiner: Norio Taniguchi in 1974.
• Key Principle: At the nanoscale, properties of materials change due to increased surface area-to-volume ratio and quantum effects.
• Nanomanufacturing Approaches:
  • Top-down: Reducing a large material to nanoscale (e.g., lithography).
  • Bottom-up: Building from atoms/molecules up (e.g., chemical vapor deposition).
• Dimensionality of Nanomaterials:
  1. 0D: All dimensions at nanoscale (e.g., Quantum Dots).
  2. 1D: Two dimensions at nanoscale (e.g., Carbon Nanotubes, Nanowires).
  3. 2D: One dimension at nanoscale (e.g., Graphene, Thin Films).
  4. 3D: Bulk material with a nanostructure (e.g., Polycrystals, Nanocomposites).
• Graphene: A 2D, single-atom-thick layer of carbon. Known for exceptional strength, and electrical and thermal conductivity. Discovered by Andre Geim and Konstantin Novoselov (Nobel Prize 2010).
• Carbon Nanotubes (CNTs): Cylindrical molecules of rolled-up graphene. Discovered by Sumio Iijima in 1991. Can be metallic or semiconducting based on their structure (chirality).
• Quantum Dots (QDs): Semiconductor nanocrystals. Their color of emitted light depends on their size (quantum confinement).
• Nano Mission (India): Launched in 2007 by the Department of Science and Technology (DST).
• Nano Urea: A liquid nano-fertilizer developed by IFFCO to improve Nitrogen Use Efficiency (NUE).
• Applications Examples:
  • Sunscreen: ZnO and TiO₂ nanoparticles for UV protection.
  • Textiles: Silver nanoparticles for antimicrobial properties.
  • Vaccines: Lipid Nanoparticles (LNPs) used in mRNA COVID-19 vaccines.
  • Displays: Quantum Dots used in QLED TVs.

Mains Insights

GS Paper III: Science & Technology, Economy, Environment

• Potential vs. Peril (Dual-Use Nature): Nanotechnology is a double-edged sword.
  • Potential: It promises revolutionary advances in medicine (targeted therapy), energy (efficient solar cells), environment (clean water), and manufacturing (stronger, lighter materials). It can be a key driver for economic growth and initiatives like ‘Make in India’.
  • Peril: There are significant concerns regarding nanopollution. The long-term effects of nanoparticles on human health (e.g., respiratory and cellular damage) and ecosystems are not yet fully understood. Its dual-use nature raises security concerns about its application in sophisticated weaponry (e.g., nano-bots, advanced explosives).
• Economic Impact and Policy:
  • Case Study of Nano Urea: This is a prime example of using nanotechnology for socio-economic benefits.
    • Cause: High subsidy burden on conventional urea, low nutrient efficiency, and environmental degradation.
    • Effect: Nano urea promises to reduce the fiscal deficit by cutting subsidies, improve agricultural productivity and soil health, and enhance food security, aligning with the goal of doubling farmers’ income.
  • Need for an Ecosystem: India’s success in nanotechnology depends not just on R&D (supported by the Nano Mission) but also on creating a robust ecosystem for commercialization, intellectual property protection, and skilled human resources.
• Environmental Dimensions:
  • As a Solution: Nanotechnology offers tools for environmental remediation, such as nano-filters for water purification, nanocatalysts for pollution control, and nanosensors for detecting pollutants.
  • As a Problem: The lifecycle of nanomaterials is a concern. The release of engineered nanoparticles into the air, water, and soil could have unforeseen toxicological effects on flora, fauna, and human health, a field of study known as nanotoxicology. The “precautionary principle” must be applied.

GS Paper II: Governance & Social Justice

• Regulatory Framework: India needs a comprehensive and dynamic regulatory framework for nanotechnology.
  • Challenge: The rapid pace of innovation outstrips the development of regulations. There is a need for clear guidelines on the manufacturing, handling, and disposal of nanomaterials.
  • Way Forward: An inter-ministerial body could be established to oversee nanotechnology, integrating health, environmental, and commercial perspectives, similar to frameworks like REACH in the European Union.
• The “Nanodivide”: There is a risk of a “nanodivide” emerging—a gap between countries and communities that have access to the benefits of nanotechnology and those that do not. Policy must ensure that the fruits of this technology, especially in healthcare and agriculture, are accessible and affordable for all sections of society to avoid exacerbating existing inequalities.

GS Paper IV: Ethics, Integrity, and Aptitude

• Ethical Concerns:
  1. Human Enhancement: The potential use of nanobots for repairing tissues or enhancing human capabilities raises profound ethical questions about the nature of being human and the potential for creating a new form of social stratification.
  2. Privacy: The development of ubiquitous, microscopic nano-sensors could lead to unprecedented levels of surveillance, posing a grave threat to individual privacy and autonomy.
  3. Informed Consent: Given the unknown long-term health risks, questions arise about informed consent for workers in nanomanufacturing industries and for consumers using nano-enabled products. The ethical principle of “do no harm” (non-maleficence) is paramount.

Previous Year Questions

Prelims

1. (UPSC Prelims 2022) With reference to the application of nanotechnology in the health sector, which of the following statements is/are correct?

   1. Targeted drug delivery is made possible by nanotechnology.
   2. Nanotechnology can largely contribute to gene therapy.

   Select the correct answer using the code given below: (a) 1 only (b) 2 only (c) Both 1 and 2 (d) Neither 1 nor 2

   Answer: (c) Both 1 and 2 Explanation: Nanoparticles can be engineered to deliver drugs directly to cancer cells, minimizing side effects (targeted drug delivery). They are also being developed as effective non-viral vectors to carry tools like CRISPR-Cas9 for gene therapy.

2. (UPSC Prelims 2020) Carbon nanotubes have which of the following applications?

   1. Drug and antigen delivery systems in the human body
   2. Making artificial blood capillaries for the injured part of the human body
   3. Use in biochemical sensors
   4. Carbon nanotubes are biodegradable.

   Select the correct answer using the code given below: (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) 1, 2, 3 and 4 Explanation: CNTs are explored for all these applications. Their hollow structure is ideal for drug delivery (1). Their size and biocompatibility make them suitable for artificial capillaries (2). Their electrical properties change upon binding with specific molecules, making them excellent sensors (3). Research has shown that certain functionalized CNTs can be biodegraded by enzymes in the body (4).

3. (UPSC Prelims 2019) Consider the following statements:

   1. The discovery of graphene has led to a technological revolution.
   2. It is one of the thinnest but strongest materials tested so far.
   3. It is transparent and has high electrical conductivity.
   4. It can be used in making touch screens, LCDs and organic LEDs.

   Which of the statements given above are correct? (a) 1 and 2 only (b) 3 and 4 only (c) 1, 2 and 3 only (d) 1, 2, 3 and 4

   Answer: (d) 1, 2, 3 and 4 Explanation: All statements correctly describe the properties and applications of graphene, which is a 2D nanomaterial.

4. (UPSC Prelims 2022) Which one of the following is the context in which the term “qubit” is mentioned? (a) Cloud Services (b) Quantum Computing (c) Visible Light Communication Technologies (d) Wireless Communication Technologies

   Answer: (b) Quantum Computing Explanation: A qubit, or quantum bit, is the basic unit of quantum information in quantum computing. Nanomaterials like quantum dots are being researched as a potential physical basis for creating qubits.

5. (UPSC Prelims - Model Question based on recent trends) Consider the following pairs:

   1. Nano Urea : Developed by IFFCO for enhanced nutrient use efficiency
   2. QLED Display : Uses semiconductor nanocrystals for better color gamut
   3. Lipid Nanoparticles : Used as vectors in traditional subunit vaccines

   Which of the pairs given above is/are correctly matched? (a) 1 and 2 only (b) 2 and 3 only (c) 1 only (d) 1, 2 and 3

   Answer: (a) 1 and 2 only Explanation: Pair 1 is correct. Pair 2 is correct as QLEDs use quantum dots (semiconductor nanocrystals). Pair 3 is incorrect; Lipid Nanoparticles were famously used in modern mRNA vaccines, not traditional subunit vaccines.

Mains

1. (UPSC Mains 2020) What is the basis of modern technology developed in the health sector using nanotechnology? Discuss its applications.

   Answer Framework:

   • Introduction: Define nanotechnology and explain its fundamental basis in the health sector: the ability to interact with biological systems at the molecular (nanoscale) level. Mention that this allows for unprecedented precision in diagnosis and therapy.
   • Basis of Nanotechnology in Health:
     • Size Mimicry: Nanoparticles are similar in size to biological molecules like proteins and viruses, allowing them to enter cells and interact with organelles.
     • High Surface Area-to-Volume Ratio: Enables high drug loading and attachment of multiple functional molecules (e.g., targeting agents, imaging agents).
     • Tunable Properties: Physicochemical properties (size, shape, surface charge) of nanoparticles can be precisely engineered to control their behavior in the body (e.g., circulation time, target specificity).
     • Quantum Effects: Quantum dots, for instance, exhibit unique optical properties useful for diagnostics and imaging.
   • Applications:
     • Therapeutics: Discuss Targeted Drug Delivery (reducing chemotherapy side effects), Photothermal Therapy (using gold nanoshells for cancer), and gene therapy (using nano-vectors for CRISPR).
     • Diagnostics: Mention biosensors for early disease detection, and quantum dots as contrast agents in medical imaging (e.g., MRI, fluorescence imaging).
     • Regenerative Medicine: Discuss the use of nano-fibrous scaffolds for tissue engineering to repair or replace damaged organs.
     • Vaccinology: Explain the role of lipid nanoparticles in mRNA vaccines for COVID-19, protecting the mRNA and facilitating cellular uptake.
   • Conclusion: Summarize by stating that nanotechnology is revolutionizing healthcare by shifting the paradigm from treatment to prevention and personalized medicine, though challenges related to long-term toxicity and regulation remain.

2. (UPSC Mains - Model Question) The Government of India’s Nano Mission has been pivotal in creating a research ecosystem. Critically evaluate its achievements and identify the challenges that lie ahead in translating research into commercially viable products.

   Answer Framework:

   • Introduction: Briefly introduce the Nano Mission (launched 2007, DST) and its objective to make India a global hub in nanotechnology.
   • Achievements of the Nano Mission:
     • Research Output: Significant increase in research publications, placing India among the top nations in nanoscience research.
     • Infrastructure Development: Establishment of centers of excellence and nano-fabrication facilities at premier institutions (IISc, IITs).
     • Human Resource Development: Nurtured a large pool of Ph.D.s and researchers in the field.
     • Fostering Basic Research: Promoted fundamental research across various domains of nanoscience.
   • Challenges in Commercial Translation:
     • “Valley of Death”: A significant gap exists between lab-scale research and industrial-scale production. Lack of funding and infrastructure for pilot-scale projects.
     • Industry-Academia Linkage: Weak collaboration between research institutions and industries, leading to research that is not always aligned with market needs.
     • Regulatory Hurdles: Absence of a clear, streamlined regulatory framework for nanoproducts, creating uncertainty for investors and manufacturers regarding safety and environmental standards.
     • Lack of Skilled Workforce for Manufacturing: While R&D personnel exist, there is a shortage of technicians and engineers skilled in large-scale nanomanufacturing.
     • High Cost of Technology: The initial capital investment for advanced nano-fabrication equipment is very high, acting as a barrier for startups and MSMEs.
   • Way Forward: Suggest measures like strengthening industry-academia partnerships through dedicated grants, creating a single-window regulatory body for nanoproducts, promoting venture capital funding for nano-startups, and introducing skill development programs.
   • Conclusion: Conclude that while the Nano Mission has successfully built a strong foundation in research, the next phase must focus on innovation, manufacturing, and regulation to harness the full economic potential of nanotechnology for an ‘Atmanirbhar Bharat’.

3. (UPSC Mains - Model Question) While nanotechnology offers promising solutions for environmental challenges, its own environmental and health footprint is a matter of concern. Discuss this paradox with suitable examples.

4. (UPSC Mains - Model Question) Nano-Urea is being hailed as a revolutionary step in Indian agriculture. Analyze its potential benefits for the Indian economy and environment, along with the challenges in its widespread adoption.

5. (UPSC Mains - Model Question) Discuss the ethical, legal, and social implications (ELSI) of nanotechnology. How should policymakers in India prepare to address these challenges?