Quantifying Interactions between Nanoparticles and Model Cell Membranes

Abstract

Due to their small size, nanoparticles (NPs) have the ability to penetrate pulmonary and vascular tissue, and as a result, are classified as potential human carcinogens. To examine factors that influence the interaction of functionalized NPs with cells in the body, the outer leaflet of the cell membrane was modeled with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) lipid monolayers. Polystyrene NPs without chemical modification and those functionalized with negatively charged carboxylic acid or positively charged amine groups, all with 60nm diameters, were introduced to the monolayer while environmental effects of pH and ionic strength were systematically altered. NPs displayed the largest interaction with the film in the presence of ions. At bilayer equivalent pressure, the aminated and carboxylated NPs showed appreciable monolayer insertion (with approximate area increases of 14% and 4.5%, respectively), whereas plain NPs solubilized the phospholipid, removing it from the air/water interface. All of these NP solutions contained a small mol% of detergent to prevent aggregation. Aminated and carboxylated polystyrene NPs free from additional surfactant were used to determine the effect detergent had on the surface activity of the NPs. Results will also be shown from experiments designed to determine the effect of NP charge and size (120nm), as well as how different lipid systems changed the fundamental interaction.