Nanoparticle Exam Notes

Definition of Nanoparticles

  • Materials possessing at least one dimension ranging from 1 to 100 nanometers.
  • Exhibit unique physical, chemical, and biological attributes due to:
    • High surface area to volume ratio.
    • Manifestation of quantum effects.
    • Enhanced reactivity and strength.

Two Primary Applications

  1. Energy and Environment
    • Utilized in solar panels and catalytic converters.
  2. Transportation
    • Employed in lightweight materials and self-healing coatings.

Comparison of Scanning Tunneling Microscopy (STM) vs. Atomic Force Microscopy (AFM)

STM

  • Principle: Measures tunneling current occurring on conductive surfaces.
  • Sample Requirement: Conductive or semi-conductive materials.
  • Resolution: Achieves very high resolution, potentially at the atomic level.
  • Operation: A sharp tip is positioned close to the sample surface, allowing electron tunneling.
  • Image Output: Provides information on topography and electronic properties.
  • Uses: Atom manipulation and surface analysis.

AFM

  • Principle: Measures forces exerted between the tip and the sample surface.
  • Sample Requirement: Suitable for both conductive and non-conductive materials.
  • Resolution: High resolution, ranging from molecular to atomic levels.
  • Operation: The tip physically taps the surface.
  • Image Output: Generates pure topography maps.
  • Uses: Imaging biological and soft materials.

Usefulness of Silver Nanoparticles

  • Highly effective as antimicrobials against bacteria, fungi, and viruses.
  • Effective at low concentrations.
  • Applications include wound dressings, plastics, and surgical masks.
  • NASA utilizes them for sterilizing drinking water.

Medical Use of Nanoparticles

  • Silver nanoparticles are employed as antimicrobials in wound dressings and surgical masks.

Electronics Use of Nanoparticles

  • Used in transistors and small devices for faster charging.

How Scanning Electron Microscopy (SEM) Operates

  • An electron gun emits an electron beam.
  • The beam interacts with the sample, producing secondary and backscattered electrons, as well as X-rays.
  • Secondary electrons are detected to generate surface images.

Silver Nanoparticles Summary

  • Antimicrobial Mechanism: Disrupts microbial membranes and binds to DNA.
  • Applications: Used in wound dressings and masks; effective in small amounts.

STM vs. AFM Revisited

STM

  • Principle: Employs an electron beam to scan the surface, detecting tunneling electrons.
  • Resolution: High resolution (1 to 10 nm).
  • Sample Requirement: Conductive samples or samples coated with a conductive material.
  • Image Type: Provides a 3D representation of the surface structure.
  • Limitation: Requires a vacuum environment and sample coating.

AFM

  • Principle: A cantilever tip is used to detect forces.
  • Resolution: Very high resolution, potentially at the atomic scale.
  • Sample Requirement: Compatible with any sample type.
  • Image Type: Generates pure topography images.
  • Limitation: Limited to smaller scan areas and slower scanning speeds.

Gold Nanoparticles Usefulness

  • Exhibits Surface Plasmon Resonance (SPR) optical property, absorbing and scattering light.
  • Color change is useful in biosensors.
  • Used for drug delivery, carrying therapeutic agents.
  • Stable and non-toxic.
  • Example: Used in pregnancy tests where a color change indicates a positive result.

Scientific Newsletter Article: Nanotechnology - Small Particle with Big Solutions

Definition

  • Nanoparticles range from 1 to 100 nm and possess unique optical, electrical, and mechanical properties.

Applications

  1. Medicine
    • Deliver drugs directly to diseased cells.
  2. Environment
    • Iron nanoparticles break down toxic chemicals in water.

Conclusion

  • Nanotechnology offers potential solutions to global challenges in health and environment.