On the interaction of nano-sized organic carbon particles with model lipid membranes

The cytotoxic character of atmospheric ultra-fine-particles (UFPs) has been reported in numerous, mainly epidemiological, investigations. However, the detailed mechanism, at the molecular level, leading to UFP cytotoxicity is not yet fully understood. To address this question, a better characterization of UFP toxicity in relation to chemical composition, surface area and particle number is needed. To follow this bottom-up approach, we have investigated the interaction of nano-sized organic carbon particles (NOCs), produced in ordinary combustion processes, with cell-sized unilamellar vesicles. These particles have a size in the 1-5 nm range and constitute an abundant fraction of the total carbon emission to the environment due to human activity. The investigation was performed by spectroscopically analyzing the chemical modifications of membrane lipid tails in optically trapped vesicles after exposure to NOCs. Our experimental outcomes demonstrate that they are able to induce oxidative damage to liposome membranes. This modification, in turn, leads to a change in membrane permeability, as observed by surface enhanced Raman scattering. it should be noticed that the method reported herein paves the way for a deeper comprehension of the interaction of nanomaterials with lipid membranes, in relation to both nanoparticles characteristics and membrane lipid composition. (C) 2009 Elsevier Ltd. All rights reserved.