Investigating the role of membrane composition on the stability of decorated nanoparticle aggregates

Abstract

Gold nanoparticles are a ubiquitous photosensitizer with a broad range of applications in microscopy and targeted drug delivery. Vesicles photosensitized with gold nanoparticles are promising as targeted drug delivery vehicles due to their non-invasive rupture mechanism. Controlling the vesicle properties increases control of the spatial-temporal release of cargo and drug dosage. The aggregation of gold nanoparticles affects the photoporation of these vesicles by interfering with peak SPR wavelengths. These nanoparticles cause leaflet bending deformations on the order of the nanoparticle size, while ligand chains may also disrupt local packing of lipid chains. Aggregation may be driven by the need to minimize one or both effects, but their relative contributions are unknown. In order to test the contributions of these two perturbations to membrane structure, we simulated multi-nanoparticle systems in lipid membranes of varying compositions. We used coarse-grained molecular dynamics simulation via the MARTINI forcefield to simulate simple spherical nanoparticles with a decorated ligand exterior. We found that large-scale nanoparticle aggregation depends more on ligand chain length than nanoparticle size, suggesting that aggregation of gold nanoparticles is dominated by microscopic perturbations to lipid packing.