Engineered Lipids That Cross-Link the Inner and Outer Leaflets of Lipid Bilayers

Abstract

The application of supported lipid bilayer systems as molecular sensors, diagnostic devices, and medical implants is limited by their lack of stability. In an effort to enhance the stability of supported lipid bilayers, three pairs of phosphatidylcholine lipids were designed to cross-link at the termini of their 2-position acyl chain upon the formation of lipid bilayers. The cross-linked lipids span the lipid bilayer, resembling naturally occurring bolaamphiphiles that stabilize archaebacterial membranes against high temperatures. The three reactions investigated here include the acyl chain cross-linking between thiol and bromine groups, thiol and acryloyl groups, and cyclopentadiene and acryloyl groups. All three reactive lipid pairs were found to cross-link in liposomal membranes, as determined by thin-layer chromatography, ion-spray mass spectrometry, and 1H NMR. The monolayer film properties of the reactive amphiphiles were characterized by surface pressure-area isotherms and showed that stable monolayers formed at the air-water interface with limiting molecular areas comparable to that of pure saturated phosphatidylcholine lipids. Langmuir-Blodgett bilayers of dimyristoylphosphatidylcholine incorporating 15 mol % of the reactive thiol and acryloyl lipids had diffusion coefficients comparable with pure dimyristoylphosphatidylcholine, while bilayers with more than 25 mol % of the reactive lipids were immobile, suggesting that interleaflet cross-linking of the lipids inhibited membrane diffusion. Our results show that the reactive lipids can cross-link within a lipid bilayer and are suitable for assembling supported lipid bilayers using Langmuir-Blodgett deposition. By using terminally reactive amphiphiles to build up supported lipid bilayers with cross-linked leaflets, bolaamphiphiles can be incorporated into asymmetric solid supported membranes to increase their stability in biosensor and medical implant applications.

Final Scientific/Technical Report - Biomimetic Energy Transduction: Artificial Photosynthesis in a Stabilized Lipid Membrane Coupled to a Semiconductor

“…5,6,[50][51][52] This lack of stability is a major impediment to technological implementation of lipid membranes in molecular devices, particularly when operation for extended periods is desired. 50,53,54 Polymerization of the lipid monomers is the strategy we are pursuing to overcome this problem. We have been investigating cross-linking polymerization of dienoyl-functionalized lipids (Figure 8) in an effort to create PSLBs with enhanced physical and chemical stability.…”

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

“…Bolaamphiphiles consist of two hydrophilic moieties attached by a hydrophobic functionality, resulting in a bilayer that is resistant to reorganization upon air exposure. 35 Polymerizable synthetic lipids have also been used to create a new class of stable lipid bilayers. 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.…”

Synthesis and study of the complex formation of a cationic alkyl-chain bola amino alcohol with DNA: in vitro transfection efficiency

“…The bolaamphiphile can be intercalated in lipid bilayer vesicles if the size of its hydrophobic part is close to twice of the size of the hydrophobic part of the lipid molecules [18]. Bolaamphiphiles can also acquire an U-shape to better blend with the bilayer [19][20][21].…”