Small Au nanoparticles - quantum confinement effects and atomic-scale simulations of interactions in biological environments
Lundi 16 mars 2015 11:00
- Duree : 1 heure
Lieu : ILL4, Seminar Room, 71 avenue des Martyrs - Grenoble
Orateur : Jaakko AKOLA (Department of Physics, Tampere University of Technology, Finland)
Metal nanoparticles (NPs) provide new functionalities of matter at the nanoscale. Their properties can be tuned via chemical composition, size, binding strength between the core and ligand shell, overall charge, and stability in a given medium. Quantum confinement effects arise as the NP size decreases down to a few nanometers, which is reflected, e.g., in optical properties and catalytic reactivity. In this context, gold nanoparticles (AuNPs) are among the most studied systems as they have potential for applications in molecular electronics, molecular recognition, catalysis, biolabeling and sensing, and drug delivery.
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 both cationic and anionic 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. 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.
Contact : deme@ill.fr
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