(353d) Liposomal Embedded Inorganic Nanoparticles and the Effects on Membrane Bending Elasticity and Structure Measured by Neutron Spin Echo
AIChE Annual Meeting
Topical Conference: Environmental Aspects, Applications, and Implications of Nanomaterials and Nanotechnology
Tuesday, October 31, 2017 - 1:27pm to 1:46pm
The cell membrane comprises of a lipid bilayer and is the first biological entity encountered by the nanoparticle. The lipid bilayer comprising of phospholipids are ~5 nm thick. In this treatise, we have studied the interactions of gold nanoparticles (AuNPs) and phospholipid bilayers. We have not changed the surface functionality or morphology of the AuNPs, but only its mean diameter and concentration. We have focused on hydrophobic ligand stabilized gold nanoparticle having diameter less than the bilayer thickness (3 nm) and diameter more than the bilayer thickness (6 nm). A mixture of phospholipids (zwitterionic and anionic) was used to synthesize unilamellar vesicles in the 100 nm diameter size range. These vesicles are convenient models for studying cell membrane properties as most eukaryotic cells comprises of similar lipids. During synthesis of these vesicles in the presence of the hydrophobic nanoparticles, the 3 nm and 6 nm diameter AuNPs preferentially embed into the hydrophobic acyl region of the lipid bilayer. We hypothesize that the 3 nm AuNPs embed easily in the bilayer without compromising its integrity significantly, but the 6 nm AuNPs causes significant disruption of the bilayer due to a mismatch.
To answer our hypothesis, we have examined the bilayer thickness and membrane bending elasticity by utilizing Small Angle Neutron Scattering (SANS) and Neutron Spin Echo (NSE) spectrometry. Bending elasticity is a mechanical property that controls the thermal fluctuations of bilayer. We have attempted to explain the influence of AuNPs of different sizes and concentration on the bending elasticity of the model bilayer at a range of temperatures from the fluid to the gel phase. Most research focuses on measuring structure of bilayers by static methods only like SANS and x-ray scattering. NSE spectroscopy is the most suitable method for our studies because it is a dynamic method and is ideal for measuring thermal fluctuations in lipid bilayers because of its correlation times and length scales overlap with cell membrane fluctuations.