title: Phospholipid composition modulates carbon nanodiamond-induced alterations in phospholipid domain formation.
abstract: The focus of this work is to elucidate how phospholipid composition can modulate lipid nanoparticle interactions in phospholipid monolayer systems. We report on alterations in lipid domain formation induced by anionically engineered carbon nanodiamonds (ECNs) as a function of lipid headgroup charge and alkyl chain saturation. Using surface pressure vs area isotherms, monolayer compressibility, and fluorescence microscopy, we found that anionic ECNs induced domain shape alterations in zwitterionic phosphatidylcholine lipids, irrespective of the lipid alkyl chain saturation, even when the surface pressure vs area isotherms did not show any significant changes. Bean-shaped structures characteristic of dipalmitoylphosphatidylcholine (DPPC) were converted to multilobed, fractal, or spiral domains as a result of exposure to ECNs, indicating that ECNs lower the line tension between domains in the case of zwitterionic lipids. For membrane systems containing anionic phospholipids, ECN-induced changes in domain packing were related to the electrostatic interactions between the anionic ECNs and the anionic lipid headgroups, even when zwitterionic lipids are present in excess. By comparing the measured size distributions with our recently developed theory derived by minimizing the free energy associated with the domain energy and mixing entropy, we found that the change in line tension induced by anionic ECNs is dominated by the charge in the condensed lipid domains. Atomic force microscopy images of the transferred anionic films confirm that the location of the anionic ECNs in the lipid monolayers is also modulated by the charge on the condensed lipid domains. Because biological membranes such as lung surfactants contain both saturated and unsaturated phospholipids with different lipid headgroup charges, our results suggest that when studying potential adverse effects of nanoparticles on biological systems the role of lipid compositions cannot be neglected.
authors: †Department of Chemical and Petroleum Engineering and ‡Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States.
authors: Aishik
authors: A
authors: Chakraborty
authors: †Department of Chemical and Petroleum Engineering and ‡Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States.
authors: Nicolas J
authors: NJ
authors: Mucci
authors: †Department of Chemical and Petroleum Engineering and ‡Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States.
authors: Ming Li
authors: ML
authors: Tan
authors: †Department of Chemical and Petroleum Engineering and ‡Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States.
authors: Ashleigh
authors: A
authors: Steckley
authors: †Department of Chemical and Petroleum Engineering and ‡Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States.
authors: Ti
authors: T
authors: Zhang
authors: †Department of Chemical and Petroleum Engineering and ‡Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States.
authors: M Laird
authors: ML
authors: Forrest
authors: †Department of Chemical and Petroleum Engineering and ‡Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States.
authors: Prajnaparamita
authors: P
authors: Dhar
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D002244:Carbon / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D008962:Models, Theoretical; D058612:Nanodiamonds / Q000737:chemistry*; D010743:Phospholipids / Q000737:chemistry*
chemical_list: D058612:Nanodiamonds; D010743:Phospholipids; D015060:1,2-Dipalmitoylphosphatidylcholine; D002244:Carbon