(316c) Using Functionalized DNA Nanostrands as Sensitive Biosensors

Current biology research and detection are based on averaged information from a relatively large sample size, which limits our investigation of rare cell behavior (e.g. cancer stem cells) and the possibility of early disease diagnosis. Furthermore, most of existing methods require more than 106 cells and long assay times to detect proteins or nucleic acids of interest because of the resolution limit of the detection methods. It would be highly valuable to have new techniques capable of biomolecular analysis at the individual cell or even single molecule basis. The large aspect ratio of the nanoporous materials offers a potential for sensing biological species at a single molecular level with fast response. The sensitivity of such depends strongly on the size of the nanochannels, i.e., smaller the pore diameters leading to more sensitive detection. However, it is very difficult and expensive to fabricate nanochannel(s) with the pore sizes smaller than 5 nm without the substantial defects from the top-down approach. Recently, we developed a novel DNA Combing and Imprinting (DCI) process to fabricate adjustable nanochannel arrays using functionalized dsDNA as the template, called DNA nanostrands. These DNA nanostrands were simply generated on the micro patterned PDMS stamp in a molecular combing process by fast de-wetting. They were then transferred onto a solid substrate such as a glass plate or a silicon wafer and cast with a liquid polymeric resin to from a confined nanoscopic elements. By conjugating various complimentary nucleic acids, antibody molecules or nanoparticles onto the dsDNA chains before DCI, the gallery spacing in the DNA nanostrands can be adjusted and the surface of DNA nanostrands can be functionalized. Such configuration allows us to study ion and molecular transport in the nanoscaled domain as well as label-free detection of the nucleic acid and antigen by electrophoresis. In this study, we conjugated complementary oligo nucleic acids on calf thymus DNA, and investigated the selectivity and sensitivity of this biosensor for oligodeoxyribonucleotide (ODN) and microRNA detection.