Public release date: 20-May-2013 [ | E-mail | Share ]

Contact: Evan Lerner elerner@upenn.edu 215-573-6604 University of Pennsylvania

The allure of personalized medicine has made new, more efficient ways of sequencing genes a top research priority. One promising technique involves reading DNA bases using changes in electrical current as they are threaded through a nanoscopic hole.

Now, a team led by University of Pennsylvania physicists has used solid-state nanopores to differentiate single-stranded DNA molecules containing sequences of a single repeating base.

The study was led by Marija Drndi, an associate professor in the Department of Physics and Astronomy in the School of Arts and Sciences, along with graduate students Kimberly Venta and Matthew Puster and post-doctoral researchers Gabriel Shemer, Julio A. Rodriguez-Manzo and Adrian Balan. They collaborated with assistant professor Jacob K. Rosenstein of Brown University and professor Kenneth L. Shepard of Columbia University.

Their results were published in the journal ACS Nano.

In this technique, known as DNA translocation measurements, strands of DNA in a salt solution are driven through an opening in a membrane by an applied electric field. As each base of the strand passes through the pore, it blocks some ions from passing through at the same time; amplifiers attached to the nanopore chip can register the resulting drop in electrical current. Because each base has a different size, researchers hope to use this data to infer the order of the bases as the strand passes through. The differences in base sizes are so small, however, that the proportions of both the nanopores and membranes need to be close those of the DNA strands themselves a major challenge.

The nanopore devices closest to being a commercially viable option for sequencing are made out of protein pores and lipid bilayers. Such protein pores have desirable proportions, but the lipid bilayer membranes in which they are inserted are akin to a film of soap, which leaves much to be desired in terms of durability and robustness.

Solid-state nanopore devices, which are made of thin solid-state membranes, offer advantages over their biological counterparts they can be more easily shipped and integrated with other electronics but the basic demonstrations of proof-of-principle sensitivity to different DNA bases have been slower.

"While biological nanopores have shown the ability to resolve single nucleotides, solid-state alternatives have lagged due to two challenges of actually manufacturing the right-sized pores and achieving high-signal, low-noise and high-bandwidth measurements," Drndi said. "We're attacking those two challenges here."

Read the original here:
Penn research makes advance in nanotech gene sequencing technique

Comments are closed.