Lateral Mobility of Tethered Vesicle−DNA Assemblies

Abstract

Supported lipid membranes are particularly attractive for use in biochemical assays because of their resistance to nonspecific adsorption and their unique ability to host transmembrane proteins. Although ideal for use in many surface-based detection techniques, supported bilayers can make the incorporation of proteins problematic due to the steric constraints of the underlying substrate. A recently developed strategy overcomes this obstacle by tethering liposomes to supported lipid bilayers via cholesterol-tagged DNA. Due to the fluidity of the bilayer, the vesicle assemblies exhibited significant lateral mobility. The corresponding diffusion coefficients were then investigated using fluorescence recovery after photobleaching (FRAP). The diffusivity was neither sensitive to the size of the vesicles nor to the length of the DNA tether. However, changing from single cholesterol tethers to double cholesterol tethers caused a decrease in the diffusivity of the assemblies by a factor of 3. Perhaps even more notable was the fact that single cholesterol-DNA without vesicles diffused 6 times faster than the corresponding assemblies. Double cholesterol-DNA diffused 11 times faster. This discrepancy is believed to arise from the fact that each vesicle is tethered to the bilayer by multiple DNA pairs.

Application of nucleic acid–lipid conjugates for the programmable organisation of liposomal modules

“…Liposomes had been assembled on solid interfaces, where the anchoring points remain fixed and hence the liposomes are laterally immobile [109][110][111], as well as fluid interfaces such as surface supported lipid bilayers, where the liposomes are then free to diffuse in two dimensions [112][113][114][115][116].…”

“…The lateral mobility of planar bilayer-tethered liposomes has been characterised by FRAP [112] and single particle tracking [115]. FRAP studies with cholesterol-tagged DNAs found that liposome mobility was independent of tether length (in the range 15 30 bases) and liposome diameter (in the range 30 100 nm) [112].…”

Specific Binding of Different Vesicle Populations by the Hybridization of Membrane-Anchored DNA

“…18,19 However, to the best of our knowledge, this is the first study of vesicle-vesicle interactions mediated by the hybridization between complementary DNA strands. We use ssDNA oligonucleotides with a cholesterol modification on one of the ends (chol-DNA).…”

Supported lipid bilayers, tethered lipid vesicles, and vesicle fusion investigated using gravimetric, plasmonic, and microscopy techniques

“…5͒. This and similar DNA constructs have been and are currently used by us and others for site-selective sorting of vesicles in combination with optical wave guide lightmode spectroscopy ͑OWLS͒, 41 for studies of the lateral mobility of tethered vesicles 42,43 including the kinetics of DNA-hybridization induced docking events 44 and for studies of three-dimensional networks of lipid vesicles, 45 in which case the full sensing volume of conventional SPR sensors can be efficiently utilized. 46 As demonstrated in Sec.…”