Specific DNA Duplex Formation at an Artificial Lipid Bilayer: towards a New DNA Biosensor Technology

A novel technique is described which comprises a base-specific DNA duplex formation at a lipid bilayerH2O-phase boundary layer. Two different probes of oligonucleotides both carrying a double-tailed lipid at the 5′-terminus were incorporated into stable artificial lipid bilayers separating two compartments (cis/trans-channel) of an optically transparent microfluidic sample carrier with perfusion capabilities. Both the cis- and trans-channels are filled with saline buffer. Injection of a cyanine-5-labeled target DNA sequence, which is complementary to only one of the oligonucleotide probes, into the cis-channel, followed by a thorough perfusion, leads to an immobilization of the labeled complementary oligonucleotide on the membrane as detected by single-molecule fluorescence spectroscopy and microscopy. In the case of fluorescent but non-complementary DNA sequences, no immobilized fluorescent oligonucleotide duplex could be detected on the membrane. This clearly verifies a specific duplex formation at the membrane interface.