AVS 45th International Symposium
    Biomaterial Interfaces Group Tuesday Sessions
       Session BI+AS+MM+NS+SS-TuA

Paper BI+AS+MM+NS+SS-TuA9
Sieving of DNA Molecules in Nanofluidic Channel

Tuesday, November 3, 1998, 4:40 pm, Room 326

Session: Nanoscale to Mesocale Biomaterial Structures
Presenter: J. Han, Cornell University
Authors: J. Han, Cornell University
H.G. Craighead, Cornell University
Correspondent: Click to Email
Entropic trapping and sieving effect of long DNA molecules was studied in variable thickness nanofluidic channels. We used photolithography and etching techniques to define fluid channels on Si wafers, and anodic bonding method to seal the channel with a thin pyrex glass coverslip. The channel consists of alternating regions with two different channel thicknesses(~100nm and 1.6µm). We studied electrophoretic motion of lambda phage DNA in this channel by epi-fluorescence microscopy. Since the radius of gyration of a typical long DNA molecule is larger than the smaller gap of the channel, the shallow part of the channel can be an entropic barrier for DNA motion.Therefore, DNA molecules were retarded when they entered into the thin region from the thick region. We measured the mobility of DNA molecules in these channels and observed that below a certain electric field, mobility of DNA molecule decreased to near zero drastically, showing that DNA molecules be entropically trapped and sieved. The threshold electric field was mainly dependent on the geometry of channel(e.g. gap size) and the length of DNA driven. This suggests a new type of separation device for DNA and other polymers.