Effect of Curcumin on the Diffusion Kinetics of a Hemicyanine Dye, LDS-698, across a Lipid Bilayer Probed by Second Harmonic Spectroscopy

Abstract

The diffusion kinetics of a hemicyanine dye, LDS-698, across model membrane bilayers was studied in real time by the surface specific second harmonic technique. Using liposomes made from different headgroups, it has been established that the diffusion is initiated by electrostatic adsorption of the positively charged dye to the outer surface of negatively charged liposomes and its time constant is affected by the rigidity of the bilayer. In the presence of the liphophilic drug curcumin (curcumin/lipid mole ratio ~ 0.2), the diffusion of LDS-698 was observed to be faster by ~56 times (from 780 to 14 s) at 25 °C. Under similar curcumin concentration, when cholesterol containing liposomes are used at 2 °C, the observed diffusion time constant increases from 14 to 65 s, showing that the effect of curcumin is superior to the effect of increasing bilayer rigidity on the diffusion process. Control experiments with other lipophilic molecules such as DPH and Nile Red showed that the effect of liposomal curcumin is superior. Consistent with previous reports of curcumin affecting the bilayer organization, this study additionally demonstrates increased permeability of liposomal curcumin, in particular against organic cations. It is speculated that origin of this enhanced membrane permeability by lipophilic molecules may depend upon the interaction of the molecule with the polar headgroup region of the lipid which, in turn, is expected to depend on the chemical structure of the molecule.

pH‐Dependent Interaction of Four Different Bile Salts with POPG Liposomes Studied by Dynamic Light Scattering and Second Harmonic Spectroscopy

“…Therefore by monitoring the time dependent SH signal, which is proportional to the population difference of the ions adsorbed between the outer and inner surface the ionic transport process can be monitored in real time. The capability of this technique has first been demonstrated using an organic cation Malachite Green and later an organic anion Chlorin‐p6 and an organic cation LDS + . In this study we have used the LDS + ion to monitor its transport kinetics across the POPG bilayer in presence of the bile acids.…”

“…The instantaneous increase (< 1 second) in the E 2ω signal after addition of LDS + ions at 50 second time point is due to the rapid electrostatic adsorption of the positively charged dye on the negative charged outer bilayer surface of POPG liposomes. From here on, the E 2ω signal is dominated by contribution coming from the LDS + ions as demonstrated earlier . The E 2ω signal of LDS + ions decreases thereafter due to the transport of the LDS + from the outer to inner POPG lipid bilayer.…”

Shea butter solid nanoparticles for curcumin encapsulation: Influence of nanoparticles size on drug loading

“…This could be related to the presence of the polyphenol between the carbon chains in the lamellar structure leading to an increase of the repetition distance. This increase (2.3 Å for the 3L structure) did not correspond to the curcumin size (close to 16 Å long and 4–5 Å wide) but the repetition distances determined by XRD corresponded to an average of the lipid structure. A lower shift toward lower angles was also reported for the double chain length structure.…”

Molecule‐Membrane Interactions in Biological Cells Studied with Second Harmonic Light Scattering

“…It was expected that the rate of transport across the CM shouldb es imilar to those obtained from prior liposome-based studies. [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] In both cases, the molecular probe has to directly diffusea cross the lipid bilayer.S till, the deduced average moleculart ransport rate for the bacterial CM is found to be an order of magnitude slower compared to unilamellar liposomes (ca. 10 À3 s À1 )w hose lipid composition was homogeneous.…”

“…Following this demonstration,anumber of studies have since examined the effects of lipid composition and av ariety of environmental factorso nt he propensity and characteristics of molecular transport across membranes in model liposome systems. [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] The studies on liposomes suggested the feasibility that SHS could be used for monitoring molecular transport across membranesi nl iving biological cells. Indeed, in 2010, our laboratory reportedt he first demonstration that SHS could be applied to study molecular transport across membranes in living cells.…”