Comparative spectroscopic studies on liposomes containing chlorophyll a and chlorophyllide a

Abstract

Abstract. Chlorophyll a (Chla) and chlorophyllide a (Chlida) -a derivative of Chla, have been incorporated in the lipid bilayers of two types of liposomes, small unilamellar vesicles (SUV) and multilamelar vesicles (MLV). The objective of the present work was to compare the spectral behaviour of Chla and Chlida incorporated in the lipid bilayers and their sensing behaviour at molecular level. The VIS absorption and fluorescence emission presented differences depending on the type of liposomes and inserted pigment, reflecting the different localization of porphyrin macrocycle in the lipid moieties. The temperature dependence of emission anisotropy and fluorescence intensity, for both Chla and Chlida incorporated in DPPC SUV, revealed the presence of different lipid phases. The degree of incorporation of quercetin (QCT) in liposome membrane was studied by using Chla and Chlida as molecular sensors. The fluorescence polarisation data and the fluorescence quenching process provided arguments for the insertion of the QCT at the interface lipid/water, in the vicinity of lipid polar heads and porphyrin macrocycle. The phytyl chain of Chla penetrating in the hydrophobic core of the lipid bilayers is responsible for the observed differences among Chla and Chlida in sensing the lipid phase transition and the fluorescence quenching process induced by QCT.

Sulfanilamide in solution and liposome vesicles; in vitro release and UV-stability studies

“…MLV, LUV and SUV liposomes with incorporated SA were prepared according to the thin-film hydration method, as previously described (Milenkovic et al, 2013, Petrović et al, 2014) with slight modifications. The PC lipid was dissolved in chloroform at the molar concentration of 5 × 10 −4 M. The SA dissolved in PBS was added to the lipid at the concentration of 1 × 10 –5 M, considering the final buffer volume of liposome suspension.…”

Biohybrids Based on Carbon Nanotubes and Liposomes – Biophysical Studies

“…Chla embedded in artificial lipid bilayers was used as a spectral marker and some spectral criteria were developed to monitor the interactions between CNTs and liposomes. All spectra were corrected as regarding the Rayleigh scattering as described previously [21,22,25] and then normalized versus the absorption at the maximum in red.…”

“…The addition of SWCNTs to liposome suspensions has no effect on the position of the Chla red maximum (671 nm for samples A and C; 670 nm for B and D), so the location of Chla in lipid bilayers was not affected, the porphyrin ring of Chla maintaining its location at the lipid-water interface in the vicinity of polar lipid heads [21].…”

“…Chlorophyll a extracted from fresh spinach leaves as described previously [20] was incorporated into artificial lipid bilayers (Chla/lipid molar ratio = 1/100) during the lipid film preparation, in order to use this phytopigment as a spectral marker, to monitor the modifications occurred in the biomimetic membranes. Our previous work [21][22][23][24][25][26] demonstrated that Chla is an excellent sensor to detect any change happened in artificial lipid bilayers. Quercetin (Q), a plant pigment and a powerful natural antioxidant, was inserted in lipid membranes (Q/lipid molar ratio = 1/100).…”

Ecobiophysical Aspects on Nanosilver Biogenerated fromCitrus reticulataPeels, as Potential Biopesticide for Controlling Pathogens and Wetland Plants in Aquatic Media

“…Chla. Small unilamellar vesicles (SUVs) labeled with Chla were prepared according to [23,24], by hydrating a soybean lecithin/Chla (100 : 1, molar ratio) thin film with phosphate buffer (PB, KH 2 PO 4 -Na 2 HPO 4 pH 7.4), followed by mechanical stirring (VIBRAX stirrer-OHIO 43230, USA, 200 rpm, 40 min), and then subjected to ultrasound treatment (Hielscher Ti probe sonicator, UP 100 H-Hielscher Ultrasonics GmbH, 14513 Teltow, Germany).…”