Département de chimie moléculaire

Decorating lipid bilayers with oligonucleotides has great potential for both fundamental studies and applications, taking advantage of the membrane properties and the specific Watson-Crick base pairing. Here, the authors systematically studied the binding of DNA oligonucleotides with the frequently used hydrophobic anchors cholesterol, stearyl, and distearyl to supported lipid bilayers made of dioleoylphosphatidylcholine (DOPC) by quartz crystal microbalance with dissipation monitoring and spectroscopic ellipsometry (SE). All three anchors incorporate well into DOPC lipid membranes, yet only the distearyl-based anchor remained stable in the bilayer when it was rinsed. The unstable anchoring of the cholesterol- and stearyl-based oligonucleotides can, however, be stabilized by hybridization of the oligonucleotides to complementary DNA modified with a second hydrophobic anchor of the same type. In all cases, the incorporation into the lipid bilayer is limited by mass transport, although micelle formation likely reduced the effective concn. of available oligonucleotides in some samples, leading to substantial differences in binding rates. Using a viscoelastic model to det. the thickness of the DNA layer and elucidating the surface coverage by SE, at equal bulk concns. double-stranded DNA constructs attached to the lipid bilayer establish a layer that is thicker than that of single-stranded oligonucleotides, whereas the DNA surface densities are similar. Shortening the length of the oligonucleotides, however, does alter both the thickness and surface d. of the DNA layer. At the bulk oligonucleotide concns. employed in the authors' expts., the packing of the oligonucleotides is not affected by the anchor type, but rather by the length of the DNA. The results are useful for material and biomedical applications that require efficient linking of oligonucleotides to lipid membranes. [on SciFinder(R)]