Nanotechnology Essentials Summary

Nanotechnology: Quick Reference

Nano: Core Definitions

  • Nanotechnology: an emerging technology where the structure of matter is controlled at the nanometer scale to produce novel materials and devices with useful properties. Defined by the US Foresight Institute as an emerging technology in which the structure of matter is controlled at the nanometer to produce novel materials and devices that have useful and unique properties.
  • Size term: nano means the billionth of a meter, 10−9 m10^{-9}\text{ m}. Technology with dimensions below 100 nm100\ \text{nm} is commonly described as nanotechnology. Also called atomically precise technology (APT).
  • Nanoscience: studies phenomena, properties, and responses of materials at atomic, molecular, and macromolecular scales.
  • History snapshot: nanomaterials used as early as the 4th century AD (Romans used nanoparticles in glass/cups; stained glass with gold/silver nanoparticles). Feynman (1959) popularized concept in "There’s Plenty of Room at the Bottom." Norio Taniguchi (1974) coined the term nanotechnology.

Scale and Size

  • Nanomaterials operate at scales where particles have unique properties different from bulk materials.
  • Paper thickness: 105 nm10^{5}\text{ nm}. Hair diameter: 5×104 nm5\times 10^{4}\text{ nm} to 1.8×105 nm1.8\times 10^{5}\text{ nm}.
  • Nanoscale gold can appear red/purple, not the familiar bulk yellow, due to size-dependent optical properties.

History and Milestones

  • Key milestones:
    • 4th century AD: Romans used nanomaterials in glass; nanoparticle-containing glasses.
    • 1959: Richard Feynman’s lecture introducing molecular-manufacturing concepts.
    • 1974: Term "nanotechnology" coined by Norio Taniguchi.
    • 1981: Scanning Tunneling Microscope (STM) invented; 1986: Atomic Force Microscope (AFM).
    • Modern activity: >2,500 patents filed annually in major offices.
    • Electronics miniaturization examples: 0.35 μm0.35\ \mu\text{m} (Pentium II, 1997) and 65 nm65\ \text{nm} (Pentium 4, 2004).

Approaches to Nanotechnology

  • Top-down: manufacture by reducing size of objects (e.g., micro- to nanoelectronics). Example: device miniaturization.
  • Bottom-up: material builds itself via chemical synthesis or self-assembly (e.g., polymers, living-system assembly).

Nanomaterials: Properties and Types

  • Bulk particles vs nanoparticles: nanoscale particles exhibit unique physical, mechanical, chemical, and optical properties.
  • Common nano-materials include carbon nanotubes (CNTs), fullerenes, quantum dots, quantum wires, nanofibers, and nanocomposites.
  • EPA (2007) categorization of nanomaterials into four types:
    1. Carbon-based materials: hollow spheres/ellipsoids (fullerenes) and nanotubes; used in bearings/seals.
    2. Metal-based materials: quantum dots, nanogolds, nanosilvers, and metal oxides (e.g., TiO$2$); quantum dots have tunable optical properties; nanogolds/silvers for biomedical applications; TiO$2$ antimicrobial for water treatment.
    3. Dendrimers: nanosized, branched polymers with numerous terminal groups for drug delivery/biochemical actions.
    4. Nanocomposites: nanoparticles integrated into matrices to enhance mechanical, thermal, and flame-retardant properties; used in energy storage/conversion.

Applications and Impacts

  • Medicine: dendrimers enable targeted drug delivery; dendrimeric structures can recognize diseased cells, diagnose, deliver drugs, and report outcomes.
  • Gold nanoshells: can deliver drugs (e.g., lapatinib, docetaxel) inside breast cancer cells, potentially reducing side effects.
  • First aid innovations: waterproof elastic bandages with nanopillars (gecko-inspired) that interact with skin/biosurfaces for adhesion; designed to dissolve in the skin over time.
  • Carbon nanotubes (CNTs): distinct from carbon fibers; high electronic conductivity; used as electron emitters in displays, electron guns, microwaves; CNT membranes enable water desalination and nanoscale sensing; CNTs adsorb organic/inorganic pollutants aiding water treatment.
  • Photocatalysis and TiO$_2$:
    • Anatase TiO$_2$ photocatalysis provides antibacterial effects; applicable to air/water treatment, anti-fogging, self-cleaning.
    • Self-cleaning building materials via TiO$2$ coatings on glass/ceramics/plastics; NO$x$ removal ~2×102 m/day2\times 10^{2}\ \text{m/day}; VOC removal ~6×101 m/day6\times 10^{1}\ \text{m/day}.
  • Nanofilms: thin films that are water-repellent, anti-reflective, UV/IR resistant, and scratch-resistant; used in eyeglasses, monitors, cameras.
  • Sunscreens: TiO$_2$ and ZnO provide UV protection.
  • Environmental cleanup:
    • Nanoscale zero-valent iron (nZVI) reduces contaminants such as PCE, TCE, and cis-1,2-dichloroethylene (c-DCE) via chemical reduction; used for groundwater remediation.

Environmental, Safety, and Societal Considerations

  • Essential questions:
    • What are the different uses of nanotechnology?
    • What are the dangers of using nanotechnology?
    • How can the possible risks be minimized across disciplines?