Cationic Au Nanoparticle Binding with Plasma Membrane-like Lipid Bilayers: Potential Mechanism for Spontaneous Permeation to Cells Revealed by Atomistic Simulations

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 cooperative effects where AuNP+, counterions, water, and the two membrane leaflets all contr…

Atomistic Simulations of Functional Au_{144}(SR)_{60} Gold Nanoparticles in Aqueous Environment

Charged monolayer-protected gold nanoparticles (AuNPs) have been studied in aqueous solution by performing atomistic molecular dynamics simulations at physiological temperature (310 K). Particular attention has been paid to electrostatic properties that modulate the formation of a complex comprised of the nanoparticle together with surrounding ions and water. We focus on Au-144 nanoparticles that comprise a nearly spherical Au core (diameter similar to 2 nm), a passivating Au-S interface, and functionalized alkanethiol chains. Cationic and anionic AuNPs have been modeled with amine and carboxyl terminal groups and Cl-/Na+ counterions, respectively. The radial distribution functions show tha…

Atomistic Simulations of Functional Gold Nanoparticles Au144(Sr)60 Interacting with Membranes

Gold nanoparticles (AuNps) are used in nanomedicine in, e.g., drug delivery and bio-imaging. However, it is regrettable that the understanding of nanoparticle properties in cellular surroundings is incompletely understood. Here, we have complemented our previous studies [1] by performing extensive atomistic molecular dynamics simulations of lipid membranes interacting with charged gold nanoparticles. We have elucidated the action of these nanoparticles on membranes characterized by lipid compositional asymmetry in the two leaflets, thereby unraveling the interactions of AuNPs with both the extracellular and the cytosolic sides of plasma membranes of eukaryotic cells. We have found that ther…

About detection of multimuon bundles at the EMMA array

Equations of State for White Dwarfs

This thesis is about deriving a few equations of state for white dwarfs below the regime of neutron drip. White dwarfs - also called degenerate dwarfs, composed mostly of electron-degenerate matter - are luminous and the color of the light they are emitting is white, hence their name. Because of the relatively enormous density, the gravitational potential of a white dwarf causes a collapse. White dwarfs are classified as compact objects, meaning that their life begins when a star dies, and are therefore considered as one possibility of a final stage of stellar evolution since they are considered static over the lifetime of the Universe. Star death is a point where the most of its nuclear fu…

Topology and structure of Au144(SRNH3+)60 from "Atomistic Simulations of Functional Au144(SR)60 Gold Nanoparticles in Aqueous Environment"

Positively charged monolayer-protected gold nanoparticles (AuNPs) structure and topology files for GROMACS used in DOI: 10.1021/jp301094m. The final structure of the simulation reported in DOI: 10.1021/jp301094m for the neutral case is provided. The gold nanoparticle contain a core of 144 Au atoms and 60 functionalized alkanethiol side groups (undecanyl chain, R = C11H22), each possessing a positively charged amonium terminal group. When using this structure do not forget to cite DOI: 10.1021/jp301094m. NOTE1: Different versions for the topology files are provided of both AuNPs. All versions were used for the publication. The changes only affect the core surface and therefore had no influ…

Topology and structure of Au144(SRCOO-)60 from "Atomistic Simulations of Functional Au144(SR)60 Gold Nanoparticles in Aqueous Environment"

Negatively charged monolayer-protected gold nanoparticles (AuNPs) structure and topology files for GROMACS used in DOI: 10.1021/jp301094m. The final structure of the simulation reported in DOI: 10.1021/jp301094m for the neutral case is provided. The gold nanoparticle contain a core of 144 Au atoms and 60 functionalized alkanethiol side groups (undecanyl chain, R = C11H22), each possessing a negatively charged carboxylic terminal group. When using this structure do not forget to cite DOI: 10.1021/jp301094m. NOTE1: Different versions for the topology files are provided of both AuNPs. All versions were used for the publication. The changes only affect the core surface and therefore had no in…