Condensation of Silica Nanoparticles on a Phospholipid Membrane

TL;DR

This study investigates how silica nanoparticles condense on a phospholipid membrane at the air-water interface, revealing multilayer structures and the role of surface potential in nanoparticle adsorption.

Contribution

It provides new insights into nanoparticle condensation mechanisms on lipid membranes using X-ray reflectometry and scattering techniques.

Findings

Nanoparticles form multilayer structures more than twice as thick as previously observed.

Adsorption of phospholipids correlates with silica nanoparticle condensation.

Positive surface potential due to Na+ ions facilitates nanoparticle accumulation.

Abstract

The structure of the transient layer at the interface between air and the aqueous solution of silica nanoparticles with the size distribution of particles that has been determined from small-angle scattering has been studied by the X-ray reflectometry method. The reconstructed depth profile of the polarizability of the substance indicates the presence of a structure consisting of several layers of nanoparticles with the thickness that is more than twice as large as the thickness of the previously described structure. The adsorption of 1,2-distearoyl-sn-glycero-3-phosphocholine molecules at the hydrosol/air interface is accompanied by the condensation of anion silica nanoparticles at the interface. This phenomenon can be qualitatively explained by the formation of the positive surface potential due to the penetration and accumulation of Na+ cations in the phospholipid membrane.