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, SnO 2, Al 2 O 3 –Carbon (C 60 ) 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 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