Domain Formation in DODAB–Cholesterol Mixed Systems Monitored via Nile Red Anisotropy

Abstract

The effect of the cholesterol (Ch) on liposomes composed of the cationic lipid dioctadecyldimethylammonium bromide (DODAB) was assessed by studying both the steady-state and time-resolved fluorescence anisotropy of the dye Nile Red. The information obtained combined with analysis of the steady-state emission and fluorescence lifetime of Nile Red (NR) for different cholesterol concentrations (5-50%) elucidated the presence of "condensed complexes" and cholesterol-rich domains in these mixed systems. The steady-state fluorescence spectra were decomposed into the sum of two lognormal emissions, emanating from two different states, and the effect of temperature on the anisotropy decay of Nile Red for different cholesterol concentrations was observed. At room temperature, the time-resolved anisotropy decays are indicative of NR being relatively immobile (manifest by a high r ∞ value). At higher temperature, rotational times ca. 1 ns were obtained throughout and a trend in increasing hindrance was seen with increase of Ch content.

Dioctadecyldimethylammonium:Monoolein Nanocarriers for Efficient in Vitro Gene Silencing

“…MO tends to abolish the pretransition temperature T p of DODAB, similar to what has been observed with cholesterol at low concentrations. 37,38 The DSC results clearly indicate that DODAC and DODAB systems behave differently in the presence of MO. The comparison between the transition temperatures is complex and should be made carefully.…”

Vesicle–micelle transition in aqueous mixtures of the cationic dioctadecyldimethylammonium and octadecyltrimethylammonium bromide surfactants

“…The fluorescence probe Nile Red (NR) has been extensively used as a probe for lipid aggregates, such as vesicles, due to its hydrophobic nature that allow it to be incorporated in the bilayer moiety [20][21][22][23]. In addition, this probe exhibits solvatochromic behaviour and in polar media it is observed a red shift in the emission maximum, together with fluorescence quenching, due to the capability of NR to establish hydrogen bonds with protic solvents [24].…”

Reversible Switching of a Micelle‐to‐Vesicle Transition by Compressed CO2

“…[33] The fluorescence probe Nile red (NR) has been used extensively as a probe for vesicular systems due to its hydrophobic nature, which allows the probed to be incorporated into the bilayer moiety. [34] In addition, this probe exhibits solvatochromic behavior and a redshift in the emission maximum can be observed in polar media, together with fluorescence quenching, due to the capability of NR to form hydrogen bonds with protic solvents. [35] Therefore, this approach was very useful in studying the MVT.…”