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Effects of Fullerenes on Phospholipid Membranes: A Langmuir Monolayer Study
Author(s) -
Wang Zhining,
Yang Shihe
Publication year - 2009
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200900328
Subject(s) - monolayer , brewster's angle , surface pressure , langmuir , dipalmitoylphosphatidylcholine , membrane , chemistry , phospholipid , analytical chemistry (journal) , fullerene , materials science , chemical engineering , crystallography , nanotechnology , adsorption , organic chemistry , optics , biochemistry , physics , engineering , brewster , phosphatidylcholine , mechanics
We investigate two‐component Langmuir monolayers of dipalmitoylphosphatidylcholine (DPPC)/C 60 by recording surface pressure/area ( π / A ) and surface potential/area (Δ V / A ) isotherms and by direct Brewster angle microscopy (BAM) imaging. Atomic force microscopy (AFM) is employed to study morphologies of the mixed monolayers transferred to a solid substrate by the Langmuir–Blodgett technique. C 60 is shown to have little influence on isotherms of the DPPC/C 60 monolayers even at a molar fraction as high as X C60 =0.3. The elastic modulus ( ${C_{\rm{s}}^{ - 1} }$ ) versus π curves of the DPPC/C 60 monolayers almost overlay each other, as well as that of pure DPPC, that is, the elasticities of pure DPPC monolayers and DPPC/C 60 monolayers are remarkably similar. AFM studies reveal that fullerene flocs form at low surface pressures ( π ≤15 mN m −1 ), are gradually disaggregated and dispersed in the DPPC monolayer with increasing surface pressure up to 35 mN m −1 , and are then progressively squeezed out to form protruded islands as the surface pressure increases up to 65 mN m −1 . Our work provides experimental support to the computational result that C 60 can dissolve in lipid bilayers without significantly compromising their mechanical properties, a finding which has important implications for the toxicity and development of drug vehicles from fullerene materials.