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NanoParticles:
Past, Present and Future
Schedule
• 10 am Introductions and Activity 1
– Intro to Nanoparticles (NPs)
• 10 minutes with slides
– Making of Au NPs
• 40 minutes for experiment
• 11am Activity 2
– Nanostructures
• 10 minutes with slides and video
– Making Gecko Tape
• 30 minutes for experiment
• Questions, Comments or Concerns
– Cleanup
– NanoInfusion Project
Nanoparticles
• The simplest nanomaterial
• May be human-made…
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Metal nanoparticles
Semiconductor materials
Ceramics: ZnO, SnO2, Al2O3
Carbon (C60)
• Or found naturally
– Carbon and organics
– Sulfates, nitrates (atmospheric)
Some Commercial Nanoparticles
• Colloidal chemistry (molecules to particles)
• Dispersions (inks, paints, drugs, cosmetics)
© Deb Newberry 2008
Commercial Nanoparticles : Carbon Black
Carbon black is high surface area soot, formed by
pyrolyzing heavy petroleum oils
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Has interesting conductive and mechanical properties
Primary particle size 50-200 nm, forms larger agglomerates
Used as pigment and reinforcer in tires and rubber products; also in
paints, inks, and toner
© Deb Newberry 2008
Recent Nanoparticle Products
© Deb Newberry
2002,2003,2004,2005,2006,
2007
Nanoparticles
Nanoparticles are interesting because
• Most of their atoms are on the surface:
maximum reactivity
• They are smaller than the critical length of many
processes, changing their properties
• They are small enough act like super atoms or
molecules
– Esp. around cells, moving in and out of cell membrane
Making Nanoparticles
Top down
• Milling, wet grinding (pigments, coatings,
magnetic recording media)
– van der Walls attraction limits this approach
– Requires high energy inputs
• Chemical etching
Bottom Up
• Chemical synthesis from precurors
Making Nanoparticles
Key challenge: keeping particles
dispersed
• Suspended particles
will attract each other,
unless
• Surrounding ionic
environment prevents
this: Zeta Potential
Types of Nanoparticles
• Metals
– Gold: decorative, biomedical
– Silver: conductive, biocide properties
– Aluminum: energetic applications
• Ceramics
– Silica, zirconia, ceria: coatings and structural ceramics
• Polymers
– Biomedical (nanocapsules)
• Semiconductors
– Quantum dots: light emitters and absorbers
• Carbon
– SW and MW nanotubes, buckminsterfullerene
Metal Nanoparticles
• Gold: low toxicity and reactivity,
high affinity for thiol binding
• Ideal for delivering biomolecules
– Gold nanoparticles are being investigated as carriers for
drugs such as Paclitaxel.
– Nanosized gold particles are particularly efficient in evading
the cell’s natural defenses.
Metal Nanoparticles
• Aluminum: High reactivity (oxidation)
– HIGHLY reactive, powder burns vigorously in air
– But in small particle form, a great explosive and
rocket fuel ingredient
– Formation processes
– Passivation is a challenge
Metal Nanoparticles
• Silver: High conductivity
– Formed into a coating slurry
– When slurry dries, a network of silver traces is left
– Good conductive, but transparent, coating