Photopolymerization of Diacetylene Lipid Bilayers and Its Application to the Construction of Micropatterned Biomimetic Membranes

Abstract

Photopolymerization of diacetylene-containing amphiphiles in substrate-supported bilayers has been studied in connection with the development of a new fabrication strategy of micropatterned biomimetic membrane systems. Two types of amphiphilic diacetylene molecules were compared, one being a monoalkyl phosphate, phosphoric acid monohexacosa-10,12-diynyl ester (1), and the other being a phospholipid, 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine (2). The bilayers of monomeric diacetylene amphiphiles were deposited onto substrates by the Langmuir-Blodgett/Langmuir-Schaefer methods. Both amphiphiles could be polymerized successfully on oxide and polymer-coated substrates. However, the phospholipid (2) showed a markedly higher mechanical stability of the polymerized bilayer films compared with the monoalkyl phosphate (1). Micropatterns were imposed in the bilayers by using a physical mask to protect the monomeric lipids partially upon UV irradiation. In the case of 2, monomeric bilayers could be removed selectively by ethanol after the lithographic photopolymerization, resulting in the formation of wells between the polymerized bilayers. These wells were filled with fluid phosphatidylcholine bilayers by fusion of vesicles. The rigid polymeric bilayer and the fluid biomimetic bilayer could be integrated as a composite bilayer membrane with defined spatial patterns, offering new possibilities to construct complex and versatile biomimetic membrane systems.

Supported Bilayer Lipid Membrane Arrays on Photopatterned Self‐Assembled Monolayers

“…[18] With such applications in mind there has been significant interest in the development of patterned sBLMs. A variety of approaches have been used, to date, including: 1) the creation of macroscopic, 3D, barriers to confine lipid bilayers to discrete areas; [19][20][21][22][23][24] 2) the polymerization of diacetylene containing lipids to create stable corals that could be filled with phospholipids; [25,26] 3) the direct UV irradiation (184-257 nm) of preformed sBLM through a photomask [27,28] where the exposed lipids were photodecomposed while the unexposed lipids remained fluid; 4) the patterning of self-assembled monolayer (SAM) anchor layers on gold to create regions of "fluid" phospholipid bilayer separated by regions of essentially "immobile" adsorbed lipid monolayer. In our earlier work we used microcontact printing (mCP) of cholesterol derivatives followed by "backfilling" with short-chain hydroxy terminated thiols to create the patterned SAMs, and it was found that as long as the hydroxylated region was not too large vesicles would adsorb, rupture and spread over the surface to yield bilayers Abstract: This work demonstrates the use of photocleavable cholesterol derivatives to create supported bilayer lipid membrane arrays on silica.…”

Surface Patterning with Colloidal Monolayers

“…The introduction of diffusion barriers -mostly created by photolithography -has been demonstrated to achieve a compartmentalization of the membrane. [291][292][293][294] In this chapter, a novel approach for the patterning of tethered bilayer membranes is introduced.…”

Making Lipid Membranes Rough, Tough, and Ready to Hit the Road

“…In fact, the lipid bilayer will delaminate from the support if the thin film is exposed to the air/water interface. [24][25][26][27][28][29][30][31] This detachment occurs because it is energetically unfavorable to remove the hydrophilic lipid head groups from solvation waters. Therefore, when an air bubble arrives at the surface, the membrane must reorganize to expose some of its lipid chains to the nascent air/water interface, while the rest of the lipid material becomes part of newly formed vesicles in the aqueous solution, as depicted in Figures 3a and 3b. A number of attempts to modify supported bilayers in order to protect them upon exposure to air are present in the literature.…”

“…36 These lipids usually contain two triple bonds within their hydrophobic tail region and can be either chemically polymerized or photopolymerized and have been found to be resistant to air and chemical solvent exposure. 28,29 Photopolymerization has also been used to spatially address lipid membranes for sensing applications. Finally, other attempts to stabilize lipid membranes have been achieved by employing charged lipids, thus relying on the electrostatic interactions between the bilayer and substrate.…”