Effect of Temperature and Humidity on Coarsening Behavior of Au Nanoparticles Embedded in Liquid Crystalline Lipid Membrane

Abstract

Coarsening behavior of the Au nanoparticles produced by thermal evaporation of Au onto a liquid crystalline lipid (1,2-dioleoyl-3-trimethylammonium-propane, DOTAP) membrane was investigated by subjecting the nanoparticle-embedded DOTAP membrane to two different annealing conditions (at 100 degrees C under no humidity and at 20 degrees C and 80% relative humidity). Although the coarsening rate was relatively slow because of the low temperature (from 5.6 nm in the as-deposited state to similar to 7 nm after 30 h), it was identified that at 100 degrees C without humidity the Au nanoparticles resulted in shape refinement whereas the high humidity at 20 degrees C induced self-organization of the nanoparticles into a monolayer. It was also found that annealing in both cases tended to segregate the lipid molecules from the nanoparticle array case of the high-humidity sample, the lipid segregation eventually led to and forced the nanoparticles into a tighter area. In the extensive coalescence of the Au nanoparticles.