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Research:

DNA Nano-Channel Sensors For Single Molecule Detection and Characterization

M. Venkatesan, S. Yemeni, J. Polans, R. Bashir; University of Illinois, Urbana-Champaign,

In this project funded by the NASA funded INAC (Institute of Nanoelectronics and Computing) at Purdue, we have been working on fabrication of nano-pore channels for the direct characterization of single molecules of DNA. The nanopore channels are fabricated in an SOI silicon layer using e-beam lithography and TEM beam induced shrinking of the resulting pore. When a voltage is applied across the pore, electrophoretic passage of DNA can be electrically detected through changes in the ionic current flow. When the entities traverse the pore, the ionic current is blocked and a decrease in the current can be observed. We reported the first experimental observation of a current enhancement upon DNA passage when a low background ionic conductivity is used (Chang, et al. 2004).

Figure 6: (b) Schematic of a selective nanopore channel, (b) Pulses of current as DNA passes through the nano-channel showing the discrimination between single base mismatch (Iqbal, et al. 2006)
Figure 6: (b) Schematic of a selective nanopore channel, (b) Pulses of current as DNA passes through the nano-channel showing the discrimination between single base mismatch (Iqbal, et al. 2006)

This techniques allows one to probe the DNA counterion current directly at the single molecule level. We have recently demonstrated selective nanopore channels (Figure 6), where a hair pin loop DNA was functionalized inside the nanopore channels. Target DNA strands (perfect complementary and mismatch) were translocated and DNA strands with even a single base mis-match can be detected due to differences in current pulse characteristics (iqbal, et al. 2006). This work will be extended to form arrays of nanopores and addressable electrodes for expression analysis and sequencing applications.