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…– Metal nanoparticles– Semiconductor materials

– Ceramics: ZnO, SnO2, Al2O3

– Carbon (C60)

• Or found naturally– Carbon and organics– Sulfates, nitrates (atmospheric)

© Deb Newberry 2008

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

• 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 2002,2003,2004,2005,2006,2007

Recent Nanoparticle Products

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