Influence of preparation path on the formation of discs and threadlike micelles in DSPE-PEG2000/lipid systems

Abstract

In a recent study we showed that the surfactant 1,2-distearoyl-sn-glycero-3-phosphatidylethanolamine-N-[methoxy(polyethylene glycol)-2000 (DSPE-PEG 2000 ) induce mixed micelles of either threadlike or discoidal shape when mixed with different types of lipids .In certain lipid systems the discoidal micelles adapt sizes large enough to be characterized as bilayer discs. The discs hold great potential for use in various biotechnical applications and may e.g. be used as model membranes in drug/membrane partition studies . Depending on the application, discs with certain characteristics, such as a particular size or size homogeneity, may be required. These factors can in our experience be influenced by the preparation method. In this study we systematically investigated three different PEG-lipid/lipid mixtures prepared by four commonly used preparation techniques. The techniques used were simple hydration, freezethawing, sonication and detergent depletion, and the aggregate size and structure was analyzed by cryo transmission electron microscopy (cryo-TEM) and dynamic light scattering (DLS). Our results show that the type and size of the micellar structure found, as well as the structure homogeneity of the preparation, can be modified by the choice of preparation path.

Patterned Threadlike Micelles and DNA-Tethered Nanoparticles: A Structural Study of PEGylated Cationic Liposome–DNA Assemblies

“…This discrepancy could be due to the blotting-induced pressure applied to the sample. Similar thread-like micelles have been reported in lipid-only (no DNA) systems containing DOPC or Egg-PC with DSPE-PEG2000 42–45 (in contrast to our DOPE-PEG2000), but to our knowledge this is the first time PEGylated thread-like micelles have been shown to order over large length scales (the diameter of the carbon hole is 2 µm). It has been previously reported 53 that the thickness of a water film suspended in a carbon hole can range between 10 – 500 nm.…”

“…Alongside liposomes and spherical micelles, long thread-like micelles and bilayer discs have been observed. 42–45 …”

When detergent meets bilayer: Birth and coming of age of lipid bicelles

“…Their phase behavior has been characterized [49,50]. The influence of the preparation path [51] and the effect of phospholipid hydrolysis [52] on aggregate structure have been studied. Special fluorophores were developed to study the highly curved regions of disks formed by dipalmitoylphosphatidylcholine (DPPC) and PEGylated distearoylposphatidylethanolamine (DSPE-PEG2000) disks by fluorescence resonance energy transfer [53].…”

Bio-functionalisation of polyelectrolyte microcapsules with biotinylated poly (ethylene glycol)- grafted liposomes for application in targeted drug delivery

“…During past decades, a large variety of micro-and nano-drug carriers has emerged, including liposomes [5][6][7], micelles [8][9][10] and cell ghosts [11], nanoparticles [12][13][14], microcapsules [15][16][17][18]. However, there still are many design and application problems, including stability, time of release, cost of preparation, and availability of the drug at the target issue.…”

“…To produce surfaces with dense arrays of PEG brushes, it is popular to apply PEGgrafted conjugates by spontaneous assembly on surfaces. Polymers, proteins and lipids have been immobilized with PEG by covalent coupling to the end functionalized PEG [9,163,168,185]. Functional PEG can be coated on solid surfaces [186] [160].…”