Nanoparticle-Induced Membrane Pore Formation Studied with Lipid Bilayer Arrays

Abstract

Nanoparticles are present environmentally as byproducts of industrial processes and in a wide range of consumer goods. Although toxicity studies of nanoparticles and other nanomaterials have only begun relatively recently, a diverse range of nanoparticles has already been shown to be toxic. Nanoparticle cytotoxicity assays provide little information about the mechanisms of nanoparticle toxicity, which are potentially complex and are not likely the same for diverse nanoparticle species. For this reason, artificial lipid bilayer platforms have begun to be used as model systems for controlled studies allowing variation of experimental parameters not possible with cellular studies, such as membrane and solution composition. Unfortunately, in some cases the low throughput characteristic of lipid bilayer experimentation can limit the experimental scope. We have recently described a lipid bilayer array platform with simultaneous bilayer formation and measurement over a 32-element array with ∼80% yield and no operator input following fluid addition.[1] The platform is modular and allows rapid cycling of the apparatus for repeated measurement. We have used this platform to measure the interactions of aminated and carboxylated polystyrene nanoparticles and a range metal oxide nanoparticle species with lipid bilayers in a wide variety of experimental conditions, including nanoparticle concentration, bilayer composition, bilayer charge, presence of serum protein, solution ionic strength, and pH. The array format permitted several thousand bilayers to be measured in total with sufficient redundancy to give statistical significance to measured results. Detailed analysis of the electrical measurements shows pore formation that is dependent on electric field, ionic strength, and nanoparticle species.1. “Lipid bilayer arrays cyclically formed and measured,” Bin Lu, Gayane Kocharyan and Jacob J. Schmidt, Biotechnology Journal 9, 446-451 (2014)