This title appears in the Scientific Report : 2014 

Cationic Au Nanoparticle Binding with Plasma Membrane-like Lipid Bilayers: Potential Mechanism for Spontaneous Permeation to Cells Revealed by Atomistic Simulations
Heikkilä, Elena (Corresponding Author)
Martinez-Seara, Hector / Gurtovenko, Andrey A. / Javanainen, Matti / Häkkinen, Hannu / Vattulainen, Ilpo / Akola, Jaakko
Quanten-Theorie der Materialien; PGI-1
The @journal of physical chemistry / C, 118 (2014) 20, S. 11131 - 11141
Washington, DC Soc. 2014
10.1021/jp5024026
Journal Article
Spin-based and quantum information
Please use the identifier: http://dx.doi.org/10.1021/jp5024026 in citations.
Despite being chemically inert as a bulk material, nanoscale gold can pose harmful side effects to living organisms. In particular, cationic Au nanoparticles (AuNP+) of 2 nm diameter or less permeate readily through plasma membranes and induce cell death. We report atomistic simulations of cationic Au nanoparticles interacting with realistic membranes and explicit solvent using a model system that comprises two cellular compartments, extracellular and cytosolic, divided by two asymmetric lipid bilayers. The membrane–AuNP+ binding and membrane reorganization processes are discovered to be governed by co-operative effects where AuNP+, counterions, water, and the two membrane leaflets all contribute. On the extracellular side, we find that the nanoparticle has to cross a free energy barrier of about 5 kBT prior forming a stable contact with the membrane. This results in a rearrangement of the zwitterionic lipids and nanoparticle side groups in the contact area, giving rise to the initial stage of pore formation on the membrane surface. Such behavior is not seen on the cytosolic side, where AuNP+ is spontaneously captured by the negatively charged phosphatidylserine lipids that diffuse to enrich the membrane leaflet underneath AuNP+, further pointing to AuNP+ accumulation on the inner leaflet of a plasma membrane. The results suggest AuNP+ permeation to take place through the formation of a pore together with partial nanoparticle neutralization/deprotonation, leading to membrane disruption at higher nanoparticle concentrations. The data also suggest a potential mechanism for cytotoxicity as AuNP+ binding to the extracellular leaflet may trigger apoptosis through translocation of phosphatidylserine.