Cellular entry of nanoparticles via serum sensitive clathrin-mediated endocytosis, and plasma membrane permeabilization

Abstract

Philip J Smith1, Maude Giroud2, Helen L Wiggins2, Florence Gower2, Jennifer A Thorley2, Bjorn Stolpe3, Julie Mazzolini2, Rosemary J Dyson4, Joshua Z Rappoport21Physical Sciences of Imaging for the Biomedical Sciences (PSIBS) Doctoral Training Center, School of Chemistry, 2School of Biosciences, 3School of Geography, Earth, and Environmental Sciences, 4School of Mathematics, University of Birmingham, Edgbaston, Birmingham, United KingdomAbstract: Increasing production and application of nanomaterials raises significant questions regarding the potential for cellular entry and toxicity of nanoparticles. It was observed that the presence of serum reduces the cellular association of 20 nm carboxylate-modified fluorescent polystyrene beads up to 20-fold, relative to cells incubated in serum-free media. Analysis by confocal microscopy demonstrated that the presence of serum greatly reduces the cell surface association of nanoparticles, as well as the potential for internalization. However, both in the presence and absence of serum, nanoparticle entry depends upon clathrin-mediated endocytosis. Finally, experiments performed with cells cooled to 4°C suggest that a proportion of the accumulation of nanoparticles in cells was likely due to direct permeabilization of the plasma membrane.Keywords: nanoparticles, polystyrene beads, serum, endocytosis, dynamin, clathrin, permeabilization