Contribution of headgroup and chain length of glycerophospholipids to thermal stability and permeability of liposomes loaded with calcein. (December 2019)

• Record Type: Journal Article
• Authors: Prislan, Iztok; Lokar, Maruša; Zirdum, Martina; Valant, Janez; Poklar Ulrih, Nataša
• Is Part Of: Chemistry and physics of lipids. Volume 225(2019)
• Publication Date: 2019-12
• Subjects: Phase transition -- Calcein permeability -- Differential scanning calorimetry -- Fluorescence emission spectrometry; Lipids -- Periodicals; Lipids -- Periodicals; Lipides -- Périodiques; Lipids; Periodicals; Electronic journals; 547.77
• DOI: 10.1016/j.chemphyslip.2019.104807
• Languages: English
• ISSNs: 0009-3084

Abstract

Highlights: The thermal and enthalpic stability of lipid bilayers depend on the acyl chains length. The increased salt concentrations, in general, does not influence the thermal stability of lipid bilayers. Replacing the ester bond with the ether one in phospholipids increase the thermal stability. The calcein release from phospholipid liposomes depends on the nature of the lipids and on the salt concentration. Abstract: Biological membranes are complex systems that are composed of lipids, proteins and carbohydrates. They are difficult to study, so it is established practice to use lipid vesicles that consist of closed 'shells' of phospholipid bilayers as model systems to study various functional and structural aspects of lipid organisation. To define the effects of the structural properties of lipid vesicles on their phase behaviour, we investigated their headgroup and chain length, and the chemical bonds by which their acyl chains are attached to the glycerol moiety of glycerophospholipid species, in terms of phase transition temperature, enthalpy change and calcein permeability. We used differential scanning calorimetry to measure the temperature and enthalpy changes of phase transition, and fluorescence to follow calcein release through the bilayer structure. Our data show that longer acyl chains increase the stability of the lipid bilayers, whereas higher salt concentrations decrease the thermal stability and widen the phase transitions of these lipid bilayers. We discuss the possible reasons for the observed phase transition behaviour.