Softening of phospholipid membranes by the adhesion of silica nanoparticles--as seen by neutron spin-echo (NSE).
The interactions between nanoparticles and vesicles are of significant interest both from a fundamental as well as from a practical point of view, as vesicles can serve as a model system for cell membranes. Accordingly the effect of nanoparticles that bind to the vesicle bilayer is very important with respect to understanding their biological impact and also may shed some light on the mechanisms behind the effect of nanotoxicity. In this study we have investigated the influence of small adsorbed silica nanoparticles (SiNPs) on the structure of zwitterionic DOPC vesicles. By a combination of SANS, cryo-TEM, and DLS, we observed that the SiNPs are bound to the outer vesicle surface without significantly affecting the vesicle structure. Most interestingly, by means of neutron spin-echo (NSE) local bilayer fluctuations were studied and one finds a small but marked decrease of the membrane rigidity upon binding of the nanoparticles. This surprising finding may be a relevant aspect for the further understanding of the effects that nanoparticles have on phospholipid bilayers.
Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 124, Sekr. TC 7, D-10623 Berlin, Germany. michael.gradzielski@tu-berlin.de ingo.hoffmann@tu-berlin.de.
Ingo
I
Hoffmann
Raphael
R
Michel
Melissa
M
Sharp
Olaf
O
Holderer
Marie-Sousai
MS
Appavou
Frank
F
Polzer
Bela
B
Farago
Michael
M
Gradzielski
D000268:Adhesiveness; D000327:Adsorption; D006244:Hardness; D008051:Lipid Bilayers / Q000737:chemistry*; D008422:Materials Testing; D008560:Membrane Fluidity; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure*; D033363:Neutron Diffraction; D010713:Phosphatidylcholines / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*
D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D012822:Silicon Dioxide; C017251:1,2-oleoylphosphatidylcholine