Ferrihydrite nanoparticles entrapped in shear-induced multilamellar vesicles

TL;DR

This study demonstrates how ferrihydrite nanoparticles can be entrapped within shear-induced multilamellar vesicles, revealing insights into nanoparticle-bilayer interactions and potential encapsulation strategies.

Contribution

It introduces a novel method to entrap ferrihydrite nanoparticles in multilamellar vesicles using shear flow, advancing understanding of nanoparticle-bilayer interactions.

Findings

Shear flow induces transition from lamellar gel to MLV state.

Ferrihydrite nanoparticles decrease bilayer d-spacing.

Nanoparticles stabilize MLVs by suppressing layer undulations.

Abstract

Hypothesis Ferrihydrite (Fh) nanoparticles are receiving considerable scientific interest due to their large reactive surface areas, crystalline structures, and nanoparticle morphology. They are of great importance in biogeochemical processes and have the ability to sequester hazardous and toxic substances. Here, the working hypothesis was to entrap fractal-like Fh nanoparticles, with a radius of gyration of 6.2 nm and a primary building block of polydisperse spheres with a radius of 0.8 nm, in a shear-induced multilamellar vesicle (MLV) state using a 40 wt.% polyethylene glycol dodecyl ether surfactant. Experiments Small- and Wide- Angle X-ray scattering revealed the equilibrium state of the non-ionic planar lamellar phase, the Fh dispersion, and their mixture. The MLV state was induced by using a shear flow in a Taylor-Couette geometry of a rheometer. Findings The nonionic surfactant initially exhibited a lamellar gel phase with two distinct d-spacings of 11.0 and 9.7 nm, which collapsed into the MLV state under shear flow. The Fh nanoparticles induced bilayer attraction by suppressing lamellar layer undulations, decreasing the d-spacing. These results are helpful in the understanding of the relationship between nanoparticle size and nanoparticle-bilayers interactions and provides insight on Fh encapsulations in a kinetically stable MLVs state.