1 research outputs found
Molecular-Level Modifications Induced by Photo-Oxidation of Lipid Monolayers Interacting with Erythrosin
Incorporation into
cell membranes is key for the action of photosensitizers
in photomedicine treatments, with hydroperoxidation as the prominent
pathway of lipid oxidation. In this paper, we use Langmuir monolayers
of 1,2-dioleoyl-<i>sn</i>-glycero-3-phosphocholine (DOPC)
and 1,2-dipalmitoyl-<i>sn</i>-glycero-3-phosphocholine (DPPC)
as cell membrane models to investigate adsorption of the photosensitizer
erythrosin and its effect on photoinduced lipid oxidation. From surface
pressure isotherms and polarization-modulated infrared reflection–absorption
spectroscopy (PM-IRRAS) data, erythrosin was found to adsorb mainly
via electrostatic interaction with the choline in the head groups
of both DOPC and DPPC. It caused larger monolayer expansion in DOPC,
with possible penetration into the hydrophobic unsaturated chains,
while penetration into the DPPC saturated chains was insignificant.
Easier penetration is due to the less packed DOPC monolayer, in comparison
to the more compact DPPC according to the monolayer compressibility
data. Most importantly, light irradiation at 530 nm made the erythrosin-containing
DOPC monolayer become less unstable, with a relative surface area
increase of ca. 19%, in agreement with previous findings for bioadhesive
giant vesicles. The relative area increase is consistent with hydroperoxidation,
supporting the erythrosin penetration into the lipid chains, which
favors singlet oxygen generation close to double bonds, an important
requirement for photodynamic efficiency