Association and Phase Behavior of Cholic Acid-Modified Dextran and Phosphatidylcholine Liposomes

Abstract

Preparation of Liposomes. The method of liposome preparation was described in detail in a previous paper. 1 Briefly appropriate amounts of phospholipids (DMPC) were dissolved in chloroform, and then dried under a nitrogen stream. The film was kept afterwards under vacuum for 3 h to remove all traces of organic solvents. The resulting lipid film was hydrated with 10 mM HEPES buffer (100 mM NaCl, pH=7.4) in a thermostated water bath at 38 °C (above the temperature of the gel-to-liquid crystalline phase transition (T m )). The multilamellar vesicles (MLVs) thus obtained were frozen in liquid nitrogen and thawed in the water bath at ca. 10 °C above T m , and this process was repeated five times. Large unilamellar vesicles (LUVs) were obtained from the MLVs by extrusion in a 10 mL stainless steel extruder (Lipex Biomembranes, Vancouver, BC, Canada), inserted in a thermostated cell with a recirculating water bath at 38°C. The samples were passed several times through polycarbonate filters (Nucleopore,

Impact of the structure of polyunsaturated soy phospholipids on the structural parameters and functionality of their complexes with covalent conjugates combining sodium caseinate with maltodextrins

“…Relying on both the literature (Antunes, Marques, Miguel, & Lindman, 2009;Bai, Nichifor, & Bastos, 2010;Schulz, Olubummo, & Binder, 2012;Str€ omstedt, Ringstad, Schmidtchen, & Malmsten, 2010) and our experimental data (Istarova et al, 2005;Semenova et al, 2012Semenova et al, , 2014a we can suggest the contribution of the different kinds of the interactions (electrostatic attraction between opposite charges, hydrogen bonding and predominantly hydrophobic attraction) into the complex formation between the phospholipids and the conjugates. It is significant that, as this takes place, the formed complexes show the same high level of the solubility in an aqueous medium that is inherent to the pure covalent conjugates .…”

“…First and foremost, the measured thermograms infer that bilayers of the DPPC liposomes are not destroyed by the formation of the supramolecular complex particles with the conjugates. What is more, the thermodynamic stability of the DPPC bilayers seems to become higher (Bai et al, 2010;Menger et al, 2005;de Oliveira Tiera, Winnik, & Tiera, 2010) in the cases of the complex particles studied. It was generally manifested itself both as the larger height (h peak ) and the larger area under the endothermic peak of the transition on the thermograms that meant the greater value of the molar enthalpy of the transition, △H tr (Fig.…”

Liposomes coated with hydrophobically modified hydroxyethyl cellulose: Influence of hydrophobic chain length and degree of modification

“…When liposomes are coated by a hydrophobically modified polymer, the polymer is believed to be anchored to the liposome surface by insertion of the hydrophobic groups into the liposome membrane [32][33][34][35][36]. Insertion of hydrophobic groups with different chain length could be expected to influence the release properties differently.…”

“…Coating of liposomes without electrostatic interactions is possible by attaching hydrophobic groups to the polymer. During coating the polymer is anchored to the liposome surface by insertion of the hydrophobic groups into the liposome membrane [32][33][34][35][36]. Depending on the type, length, and amount of the hydrophobic groups, the liposome may be stabilized [37,38] or destabilized and disintegrating into mixed micelles [36,37].…”

“…During coating the polymer is anchored to the liposome surface by insertion of the hydrophobic groups into the liposome membrane [32][33][34][35][36]. Depending on the type, length, and amount of the hydrophobic groups, the liposome may be stabilized [37,38] or destabilized and disintegrating into mixed micelles [36,37]. Hydrophobically modified chitosan [33,39], PNIPAAM [23], and alginate [40] as some examples, have been used for liposome coating, in addition to uncharged polymers such as hydrophobically modified poly(ethylene glycol) (PEG) [41], polyvinyl alcohol (PVA) [12] and dextran [37,38].…”