Effects of DC Magnetic Fields on Magnetoliposomes

Raymundo Rodríguez López,Jonathan S De Lira Escobedo,Milton Muñoz Navia,Perla Xochil Viveros Méndez,Armando Encinas Oropesa,Elsie Araujo,Sonia Saucedo Anaya,Said Eduardo Aranda Espinoza

doi:10.1016/j.bpj.2018.11.1978

Abstract

A modification of the co-precipitation method was used to prepare Magnetic nanoparticles (MNPs). After characterization, using Transmission Electron Microscopy and hysteresis loops analysis, we found that the nanoparticles are superparamagnetic with different geometries and size average of 12 nm. Magnetoliposomes (MLs), were prepared by rehydration, and we were able to encapsulate the superparamagnetic nanoparticles (SNPs) inside the liposomes. A DC magnetic field was applied to study the effects of the confined SNPs. Digitalized images taken from an inverted phase contrast microscope show that vesicles display two behaviors when a magnetic DC field was applied: encapsulated SNPs assembly in a pearl-chain formation and, in other cases, MLs deform in the direction of the magnetic field. Deformations are explained by analyzing the forces exerted by the magnetic field over the surface of the otherwise spheroidal vesicle. We found that tangential forces squeeze ML deforming them in a rhombohedral-like shape. When the initial surface tension of ML is high, we observe no deformation of the membrane vesicle, and instead, the pearl-chain formation of the SNPs in the inner medium of the vesicle is observed in the direction of the applied magnetic field. A dipole-dipole interaction explains this pearl-chain formation where complete disperse SNPs are observed when the magnetic field is switched off.

Highlights

1806-Pos Pinning Cholesterol Chemical Potential Impacts the Miscibility Transition in Isolated Plasma Membrane Vesicles Anna Gaffney, Thomas Shaw, Sarah L
Our results show that the membrane dynamics are enhanced during the melting transition, which we quantify as a decrease in the bending modulus
Our results provide new insights into the nanoscale membrane dynamics during the melting transition and demonstrate how these dynamics are necessary for changes in the bilayer structure

Summary

Introduction

1806-Pos Pinning Cholesterol Chemical Potential Impacts the Miscibility Transition in Isolated Plasma Membrane Vesicles Anna Gaffney, Thomas Shaw, Sarah L. When the initial surface tension of ML is high, we observe no deformation of the membrane vesicle, and instead, the pearl-chain formation of the SNPs in the inner medium of the vesicle is observed in the direction of the applied magnetic field. 1803-Pos Lipid- and Cholesterol-Mediated Timescale-Specific Modulation of Membrane Protein Dynamics Lukas Frey1, Sebastian Hiller2, Roland Riek1, Stefan Bibow2.

Results

Conclusion