Synthesis and vesicular polymerization of novel counter‐ion polymerizable/crosslinkable surfactants

Abstract

Two novel two-tail surfactants, dicetyldimethylammonium 4-vinyl benzoate (DDVB) and dicetyldimethylammonium 3,5-divinyl benzoate (DDDB), were synthesized by neutralizing the corresponding quaternary ammonium hydroxide with the appropriate benzoic acid. As expected, these surfactants formed both homo and mixedvesicles, which were readily polymerized with a suitable radical photo-initiator. The polymerization process was followed by UV-vis spectroscopy and also reconfirmed by NMR and IR spectroscopy. Polymerization of vesicles prepared from DDVB, unlike the more commonly polymerized vesicles, in which the polymerizable group forms an integral part of the surfactant, leads to the formation of a linear polyelectrolyte chain that is only electrostatically bound to the lipid bilayer. On the other hand, polymerization of DDDB vesicles leads to the formation of a crosslinked shell (or net) that encases the vesicle bilayer. Such counterion crosslinked vesicles were shown to be resistant to destabilization both by lysis as well as in the presence of a fairly high volume fraction of an organic solvent, such as ethanol. However, although the simple polymerized (linearly) vesicles, formed from DDVB, exhibit enhanced stability toward lysis when compared to their unpolymerized counterparts, they are readily destabilized in the presence of ethanol, leading to precipitation. This sharp contrast in the behavior of linearly polymerized and crosslinked systems suggests that crosslinking is essential to arrest conformational reorganization of the polyelectrolyte chains induced by a change in the solvent medium, which in turn leads to precipitation. Such counterion crosslinked vesicular systems also have an added advantage; they may retain the fluidityof the lipid bilayer while at the same time possess enhanced stability.

Polymerizable Vesicles Based on a Single-Tailed Fatty Acid Surfactant: A Simple Route to Robust Nanocontainers

“…We have shown in this paper that UDA, a single-tailed fatty acid with a terminal unsaturation on its alkyl tail, is capable of forming unilamellar vesicles over an intermediate range of pH (6)(7)(8). The presence of vesicles was demonstrated by a variety of techniques, including DLS, SANS, and cryo-TEM.…”

“…A topic of great interest over the last two decades has been the creation of robust nanosized vesicles using polymerizable lipids. [1][2][3][4][5][6][7] The latter are lipids that bear some type of reactive group along their nonpolar tail(s), such as dienoyl, acryloyl, or lipoyl groups. 4,5 Vesicles (liposomes) formed from these lipids in aqueous solution can be subsequently polymerized by heat or UV light in the presence of a suitable initiator that generates free radicals.…”

“…A topic of great interest over the last two decades has been the creation of robust nanosized vesicles using polymerizable lipids. − The latter are lipids that bear some type of reactive group along their nonpolar tail(s), such as dienoyl, acryloyl, or lipoyl groups. , Vesicles (liposomes) formed from these lipids in aqueous solution can be subsequently polymerized by heat or UV light in the presence of a suitable initiator that generates free radicals. In the process, the tails in the vesicle bilayer become linked by strong, covalent bonds, and the vesicle is thereby converted into a robust nanocontainer. , Such polymerized vesicles cannot be destabilized by addition of bilayer-disrupting agents such as ethanol or Triton X-100 (unlike unpolymerized vesicles, which have low stability because they are self-assembled structures held only by weak, noncovalent bonds).…”

Strategies in biomimetic surface engineering of nanoparticles for biomedical applications

“…The polymerization of self-assembled phospholipid structures is a frequently used strategy that results in robust biocompatible architectures. Polymerization can be designed in either the hydrophobic region 66 or the hydrophilic region 67,68 of the phospholipid. Recently, biomimetic designs and performances of polymerizable lipids have been reviewed in detail.…”

Vesicle Formation and Stability in Aqueous Mixtures of the Hydrolyzed Copolymer of Styrene−Maleic Anhydride and Conventional Single-Tailed Cationic Surfactants

“…In the past few decades, vesicles have attracted much interest due to their great significance in both theoretics and applications. , Much research has been done on exploiting new kinds of vesicle-forming systems and investigating the vesicle properties such as stability to environmental factors. Usually, vesicles formed through sonication or other mechanical disruption of the bilayer phase easily change back to flat bilayer structures or precipitate in aqueous dispersion, , which greatly hampered the potential application of the vesicles. One approach to stabilize the vesicle structure is polymerization of the molecules before , or after − their orientation in model membranes, which can limit the kinetic process of reversion.…”