Interactions between magnetic nanoparticles and model lipid bilayers—Fourier transformed infrared spectroscopy (FTIR) studies of the molecular basis of nanotoxicity

The toxicity of nanoparticles (nanotoxicity) is often associated with their interruption of biological membranes. The effect of polymer-coated magnetic nanoparticles (with different Fe3O4 core sizes and different polymeric coatings) on a model biological membrane system of vesicles formed by dimyristoylphosphatidylcholine (DMPC) was studied. Selected magnetic nanoparticles with core sizes ranging from 3 to 13 nm (in diameter) were characterised by transmission electron microscopy. Samples with 10% DMPC and different nanoparticle concentrations were studied by attenuated total reflectance—Fourier transform infrared spectroscopy to establish the influence of nanoparticles on the phase behaviour of model phospholipid systems

Radiation damage in tripalmitin layers studied by means of infrared spectroscopy and electron microscopy.

Structural deteriorations in biomembranes, as inevitably induced while structural information is gathered by electron optical methods, were evaluated by infrared spectroscopy. Tripalmitin model membranes were irradiated with 100 keV-electrons in an electron microscope. The intensity decay of group vibrations over the dose reveals the sequence of damage in the polar and nonpolar part of the molecule. The C-C backbone, being the most important structural feature, shows a significant latency effect up to 0.6 e-/A2 and is completely disordered by 3 e-/A2, corresponding to about three inelastic processes per molecule

Interaction of Two Different Types of Membrane Proteins with Model Membranes Investigated by FTIR ATR Spectroscopy

INTRODUCTION In vivo, there are several ways of how membrane proteins are attached to a lipid bilayer. We investigated two proteins with respect to their interactions with model membrane assemblies. Mitochondrial creatine kinase (Mi-CK) is known to bind effectively to the surface of negatively charged bilayers like cardiolipin (CL) (1,2,3). Mi-CK catalyzes the phosphorylation of creatine by ATP and is therefore important for energy metabolism in cells of high and fluctuating energy requirements. Alkaline phosphatase (AP) belongs to a wide group of enzymes which catalyze the non-specific hydrolysis of phosphate monoesters in an alkaline environment (4). AP is attached to the outer leaflet of the plasma membrane by the lipid moiety of a glycosyl-phosphatidylinositol (GPI) anchor (5). The hydrophobic hydrocarbon chains of this lipid moiety are responsible for the attachment of the enzyme to the lipid bilayer. Our aim was to find experimental conditions enabling the forma