Assessing the DOPC-cholesterol interactions and their influence on fullerene C60 partitioning in lipid bilayers

Abstract

We propose a computational Molecular Dynamic (MD) study to evaluate the interaction of C60 fullerene in contact with lipid membranes, as a function of the bilayers cholesterol content. Pure 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and DOPC/cholesterolXX (XX = 10%, 20% and 30%) membranes where investigated. An analysis involving umbrella pulling techniques to force the extraction of DOPC lipid and/or cholesterol molecules in comparison with an insertion of a fullerene C60 molecule into the lipid/cholesterol membranes was performed in order to verify the force/energy required for the C60@DOPC/cholesterol partitioning. In addition, electron spin resonance experiments using a lipid and an amphiphilic spin labels were performed to investigate the DOPC-cholesterol interactions and to mimic the C60 fullerene-membrane interactions. The spectroscopic results corroborated the MD ones and indicated that the presence of cholesterol in the lipid bilayers increased the membrane rigidity as well as the force required to C60 insertion/extraction.