Exploring the Toxicity of Nanoparticles: The Effect of Nanoparticles On Lipid Monolayer Stabilization

Hybrid liposome-nanoparticle systems are currently under extensive study because of their diverse application in bionanotechnology. Multicomponent liposomes (i.e. lipid bilayer vesicles) serve as model cell membranes and can help increase understanding of nanoparticle-cell interaction. Other applications of these systems range from enhanced drug delivery to improved diagnostic imaging. Of increasing importance in the field is the effect of nanoparticles on bilayer destabilization and structure. Our lab and others have shown that nanoparticle binding to liposomes can make the bilayers ‘leaky’ due to lipid disordering or the formation of water pores. To provide greater insight into nanoparticle-lipid binding mechanisms, lipid monolayers studies are being conducted as a function of nanoparticle and lipid composition. With monolayers it is possible to examine dynamic changes in lipid packing and phase behavior as a function of surface pressure. To our knowledge, little is known about the effect of nanoparticles on a single monolayer of a multicomponent lipid system. Using oppositely charged nanoparticles and monolayers, our results show that the addition of nanoparticles increases monolayer surface pressure (i.e. reduces interfacial tension) possibly by causing lipid condensation or by extracting lipids from the monolayer. Both effects could act to destabilize a lipid membrane. Our goal is to translate this knowledge to model and ultimately develop intact cell membranes for the design of nanoparticles with a specific degree of membrane activity.