(418cq) Size Dependent Interactions of Gold Nanoparticles with a Supported Lipid Bilayer

With their small size and unique surface area properties, nanoparticles are being investigated for applications spanning fields from biomedical applications to uses in consumer products. While the use of NPs in applications appears promising, the consequence of their disposal is unknown. This study serves to understand how NPs of varying sizes will interact in environmental and biological systems.  A supported lipid bilayer (SLB) was used as a model surface for NPs to interact with. The changes on the bilayer were monitored by Quartz Crystal Microbalance with Dissipation, which is able to measure frequency (inverse of mass) and dissipation (surface rigidity) changes at the nano-level in real time. Using this novel technique, we studied gold NPs of sizes 2, 5, 10, and 40 nm in water and poly(methacrylic acid) (PMA). Water simulated a clean lab condition while the poly(methacrylic acid) modelled an environment more typical of soil. In water, all particles behaved similarly with some lipid perturbation causing small amounts of mass loss from the SLB. However, when PMA was introduced onto the bilayer and coated the NPs, the interaction mechanism was altered. In PMA, the SLB-NP interaction with smaller particles (2 nm and 5 nm) resulted in mass addition onto the bilayer surface, which is due to the particles remaining in the bilayer during interaction. The 10 nm particles behaved similarly in PMA as they did in water with small amounts of lipid removal. The largest particles studied, 40 nm NPs, resulted in large mass loss (~ 60 ng) from the lipid bilayer. Simulating a typical environment in which NPs are disposed of is crucial to understand the interaction mechanisms. Our results demonstrate the importance of both NP core size and bulk solution for their fate within our environment.