Lipid Lateral Segregation Driven by Diacyl Cyclodextrin Interactions at the Membrane Surface

Abstract

Cyclodextrins are hydrophilic molecular cages with a hydrophobic interior allowing the inclusion of water-insoluble drugs. Amphiphilic cyclodextrins obtained by appending a hydrophobic anchor were designed to improve the cell targeting of the drug-containing cavities through their liposome transportation in the organism. After insertion in model membranes, they were found to induce a lateral phase separation into a pure lipid phase and a fluid cyclodextrin-rich phase (L(CD)) with reduced acyl chain order parameters, as observed with a derivative containing a cholesterol anchor (M. Roux, R. Auzely-Velty, F. Djedaïni-Pilard, and B. Perly. 2002. Biophysical Journal, 8:813-822). We present another class of amphiphilic cyclodextrins obtained by grafting aspartic acid esterified by two lauryl chains on the oligosaccharide core via a succinyl spacer. The obtained dilauryl-beta-cyclodextrin (betaDLC) was inserted in chain perdeuterated dimyristoylphosphatidylcholine (DMPC-d54) membranes and studied by deuterium NMR ((2)H-NMR). A laterally segregated mixed phase was found to sequester three times more lipids than the cholesteryl derivative (approximately 4-5 lipids per monomer of betaDLC), and a quasipure L(CD) phase could be obtained with a 20% molar concentration of betaDLC. When cooled below the main fluid-to-gel transition of DMPC-d54 the betaDLC-rich phase stays fluid, coexisting with pure lipid in the gel state, and exhibits a sharp transition to a gel phase with frozen DMPC acyl chains at 12.5 degrees C. No lateral phase separation was observed with partially or fully methylated betaDLC, confirming that the stability of the segregated L(CD) phase was governed through hydrogen-bond-mediated intermolecular interactions between cyclodextrin headgroups at the membrane surface. As opposed to native betaDLC, the methylated derivatives were found to strongly increase the orientational order of DMPC acyl chains as the temperature reaches the membrane fluid-to-gel transition. The results are discussed in relation to the "anomalous swelling" of saturated phosphatidylcholine multilamellar membranes known to occur in the vicinity of the main fluid-to-gel transition.

Physico-chemical investigation of asymmetrical peptidolipidyl-cyclodextrins

“…In subsequent advancements aiming to overcome certain difficulties encountered with phospholipidyl-cyclodextrins, namely high cost, tedious synthesis and rather poor chemical stability, a new class of amphiphilic cyclodextrins was designed [20] and referred to as the peptidolipidyl-cyclodextrins. Compared to phospholipidyl-cyclodextrins, the peptidolipidyl-cyclodextrins differ in that the chiral glycero-phosphate moiety is replaced by an amino-acid group providing the following advantages:…”

Nano-Assemblies of Modified Cyclodextrins and Their Complexes with Guest Molecules: Incorporation in Nanostructured Membranes and Amphiphile Nanoarchitectonics Design

“…Di- and polysubstituted amphiphilic cyclodextrins have been obtained by grafting of aliphatic chains or cholesteryl moieties on the primary hydroxyl groups of the cyclodextrin rim via amine, sulphur or sulfoxide linkers [ 13 , 14 , 15 , 16 , 53 , 54 ]. Studies of the interfacial properties of these compounds have shown that they may form stable monomolecular layers at the air-water interface [ 13 , 14 , 15 , 16 ].…”

“…The fact that modified cyclodextrins can be mixed in various proportions with phospholipids, cholesterol, and other amphiphilic molecules has been exploited for preparation of functionalized lipid membranes and organized biomimetic systems ( Table 2 ). Hydrated mixtures of lipids and amphiphilic cyclodextrins may spontaneously assemble into unilamellar spherical vesicles ( Figure 7 a), giant unilamellar vesicles ( Figure 7 b) or multilamellar liposomes [ 28 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 ]. More sophisticated hybrid structures, involving cyclodextrin derivatives, have been prepared by controlled deposition techniques employing nanoarchitectonics means [ 7 , 14 , 15 ].…”

“…In general, high hydrophobicity of the cyclodextrin derivatives might constitute an obstacle for their inclusion in lipid bilayer membranes owing to the preference for phase separation in two-dimensional domains. A variety of physical and physico-chemical methods (small-angle X-ray scattering (SAXS), X-ray diffraction, small-angle neutron scattering (SANS), X-ray-reflectivity, neutron reflectivity, differential scanning calorimetry (DSC), deuterium nuclear magnetic resonance ( 2 H NMR), surface pressure/area isotherms, Brewster angle microscopy (BAM), atomic force microscopy (AFM), cryogenic transmission electron microscopy (cryo-TEM), and confocal laser scanning microscopy (CLSM)) have been employed to investigate these effects [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 …”

“…An important feature for the drug delivery field comes from the fact that the majority of amphiphilic cyclodextrins are considered to be non-hemolytic and non-cytotoxic [ 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 ]. Mixed amphiphilic nanostructures of phospholipids and modified cyclodextrin have been of special interest because these systems may display high affinity for interaction with biological membranes [ 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 ].…”