We explored the influence of nanoparticle (NP) surface charge and hydrophobicity on nanoparticle-biomolecule interactions by measuring the composition of adsorbed phospholipids on four NPs, namely positively charged CeO2 and ZnO, and negatively charged BaSO4 and silica-coated CeO2 after exposure to bronchoalveolar lavage fluid (BALf) obtained from rats, and to a mixture of neutral dipalmitoyl phosphatidylcholine (DPPC) and negatively charged dipalmitoyl phosphatidic acid (DPPA). The resulting NP-lipid interactions were examined by cryogenic transmission electron microscopy (cryo-TEM) and by atomic force microscopy (AFM). Our data show that the amount of adsorbed lipids on NPs after incubation in BALf and the DPPC/DPPA mixture were highest in CeO2 than on the other NPs, qualitatively consistent with their relative hydrophobicity. The relative concentrations of specific adsorbed phospholipids on NP surfaces were different from their relative concentrations in the BALf. Sphingomyelin was not detected in the extracted lipids from the NPs despite its > 20% concentration in the BALf. AFM showed that the more hydrophobic CeO2 NPs tended to be located inside lipid vesicles while less hydrophobic BaSO4 NPs appeared to be outside. In addition, cryo-TEM analysis showed that CeO2 NPs were associated with the formation of multilamellar lipid bilayers, while BaSO4 NPs with unilamellar lipid bilayers. These data suggest that NP surface hydrophobicity predominantly controls the amounts and types of lipids adsorbed, as well as the nature of their interaction with phospholipids.
Nanoparticle Wettability Influences Nanoparticle-Phospholipid Interactions. / Konduru, Nagarjun; Damiani, Flavia; Stoilova-Mcphie, Svetla; Tresback, Jason; Pyrgiotakis, Georgios; Donaghey, Thomas C.; Demokritou, Philip; Brain, Joseph; Molina, Ramon M.In: Langmuir, 28.10.2017.
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