Increased manufacturing of engineered nanoparticles (ENPs) with commercial and biomedical applications has led to an increase in the release of these particles into the environment. Since the pulmonary route is an obvious one for the intake of these nanoparticles, concerns regarding potential health risks of these NPs has also seen a rapid increase in recent years.In this work, we describe the interaction of an engineered carbon nanoparticle (nanodiamond ENDs) with a model lung surfactant system (DPPC) both as a function of time of exposure and concentration. Using surface pressure vs. area per molecule coupled with fluorescence microscopy, we study lipid/END interactions for several weeks. Our results indicate that over short times (0-2 days exposure) the ENDs do not significantly affect the biophysical properties of this model surfactant. However after longer exposure, the ENDs begin to alter the surface tension lowering ability and domain morphology of DPPC. Our results indicate that long term exposure to these ENDs cause a lowering of line tension of the film, in a manner similar to interactions between DPPC and small (<2 wt %) amounts of cholesterol.View Large Image | View Hi-Res Image | Download PowerPoint Slide