Engineered oxide nanoparticles (EONPs) are widely applied in insulators, catalyzers, paints, cosmetic products, textiles and semiconductors. Because of their widespread application and production, EONPs will eventually enter the environment where their fate and behavior are largely unknown. They can cause toxicities to organisms by damaging their cell membrane. In this study, nano-scaled aluminum, silicon, titanium, and zinc oxides were selected as model EONPs. The membrane damages were studied through the changes in biomolecular structure, membrane integrity and fluidity. The effects of EONPs on cell surface biomolecules were studied by Fourier transform infrared spectroscopy (FTIR). EONPs induced damages to proteins and phospholipids. They caused intensity ratio decrease of �-sheets/a-helices, indicating the potential changes in protein structure and function. They also caused changes in phospholipid amine moiety. ZnO nanoparticles broke the phosphodiester bond of L-a-Phosphatidyl-ethanolamine, resulting in highly disordered alkyl chain, which is consistent with its highest toxicity among the studied EONPs. The damage to phospholipid molecular structure may lead to cell membrane rupture. Therefore the direct views to the membrane morphological changes and membrane integrity were recorded by microscopy. Giant unilamellar vesicles (GUVs) were made using 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) to simulate the real cell membrane. The GUV surface charge was adjusted to be positive or negative by adding 1,2-dipalmitoyl-3-trimethylammonium-propane (TAP) or 1,2-dipalmitoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DPPG). Membrane rupture was observed after EONPs exposure, and the process of GUV morphological changes was recorded by fluorescence confocal microscopy. The damages to cell membrane related to electrostatic force, EONPs exposure dose and time. The electrostatic force between EONPs and phospholipid molecules also changed the membrane fluidity, which was reflected by the spectrum shift of fluorecent probe inside the membrane. Cell membrane damages may affect cell physiological activities, even cause cell death.

Cell membrane damages caused by engineered oxide nanoparticles

247th National Meeting (2014)

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