2008

— Enabling Technologies and New Markets

September 15-17, 2008
Crowne Plaza
San Diego, California

WORKSHOP: Science & Technology of Nanocomposites

Part 1: Fundamentals on Nanocomposites
Instructor: Prof. Miriam Rafailovich

• Introduction: Why are nano-particles so popular?
• Structure: Survey of different types of nano-particles-and their cost.
• Polymer nanocomposites: The importance of surfaces and interfaces in nanocomposites design.
• Confined structures: Fibers, nano-patterned materials, effects of confinement and interfacial interactions on rheology.
• Characterization: Nanoscale characterization of the structure, morphology, and rheology: from microscopy to neutron scattering.
• Applications: Several examples--flame retardant materials, compatiblization, gas barriers--i.e. soda bottles.

Part 2: Polymer nanocomposites of clay, silica, and hybrid nanoparticles
Instructor: Prof. Sadhan Jana

• Introduction
• Filler-polymer compatibility
• Filler modification
• Nanocomposites synthesis strategies
• Review of properties
• Future outlook of the field

Part 3: Carbon based nanocomposites
Instructor: Prof. Fengge Gao

• Allotropic forms of carbon and their potential in nanotechnology application
• Fullerene
• Carbon nanotubes and Nanographite technology
• Carbon filler enhanced polymer nanocomposites

Part 4: Is there reason for concern regarding nanoparticle toxicity?
Instructor: Prof. Miriam Rafailovich

Nanotechnology is revolutionizing the way materials are engineered today. Because of their large surface to volume ratio nanoparticles are the driving force behind many new technologies. Inorganic functionalized nanoparticles are used to produce UV resistant and flame retardant plastics for automotive and aviation industries. Metallic nanoparticles are used as viscosity modifiers for lubricants and to control the dielectric properties of electronic coatings. Oxide particles are used in cosmetics to produce brighter pigmentation and UV protection, and magnetic nanoparticles are used to deliver chemotherapy to targeted organs or as NMR contrast enhancers.

When considering consumer applications of nanosized materials, the potential long-term adverse effects on living species must also be considered. For example, lung damage caused by nanoparticles has been reported to be more severe than that caused by conventional toxic dust (Oberdorster 2004). Lam et al. demonstrated that carbon nanotubes can cause lung granulomas in mice (Lam 2004). Other studies have shown that titanium dioxide (TiO₂), a naturally occurring mineral previously classified as biologically inert, can cause inflammatory reactions both in animals and humans when ground into particles smaller than 20 nm (Ophus 1979, Lindenschmidt 1990, Oberdorster 1994) and cells cultured in the presence of alumina or titania nanoparticles show a dramatic decrease in growth rate even after two hours of exposure (Gutwein 2004). Furthermore single-walled carbon nanotubes have been shown to elicit changes in NF-_KB signaling in response to oxidative stress leading to alterations in inflammatory cytokine expression and inhibition of cell proliferation (Manna et al, 2005).

The mechanisms (i.e.: endocytosis, pinocytosis) by which inert nanoparticles enter cells are still debated. Regardless of the method of entry, all reports thus far indicate, that once inside the cell, the particles can trigger chemical changes whose impact must be evaluated in a case by case system.

The interaction of particles with whole tissue physiology is complex. In order to understand the mechanisms leading to adverse events we have chosen to focus on the interactions of nanoparticles with cells and tissues and to evaluate viability, proliferative potential, differentiation and alterations in host response (inflammation, signal transductions, tissue remodeling), as well as determining cytotoxicity. We will explore the role of aspect ratio, size, chemistry, and coatings.

With this set of particles we will then study the processes which lead to particle penetration into the cell, storage in specific subcellular locations, and the sequence of events which occurs intracellularly once the particles have entered. These include the time it takes for cells to process the particles, the dose response, the degree to which the cells are hindered from performing their normal functions, and the ability of cells to recover once extracellular nanoparticles are removed. Finally, we will discuss what can be done to minimize adverse interactions when using nanoparticles in the design of new biomaterials and tissue scaffolds.