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Single-molecule speed control and charge state measurement in a pressure-biased solid-state nanopore

Speaker: 
Lu Bo (School of Physics, Peking University, China)
Date: 
Wed, 03/04/2013 - 11:00am to 12:00pm
Location: 
S13-M01-11 (Physics Conference Room)
Event Type: 
Seminars

Abstract

Voltage-biased solid-state nanopores are well established in their ability to detect and characterize single polymers, such as DNA, in electrolytes. The addition of a pressure gradient across the nanopore yields a second, independent molecular driving force that provides new freedom for studying molecules in nanopores. We show that opposing pressure- and voltage-derived forces allow us to detect and resolve very short DNA molecules, as well as to detect near-neutral polymer strands. Moreover, by simply balancing pressure- and voltage-derived forces in the nanopore, we were able to detect single biomolecule charge density. The measurement of the charge density of ds-DNA from pH 4 to 10 shows that the charge density of dsDNA drops significantly below pH 6, while the effective hydrodynamic radius of the DNA decreases due to the shedding of the immobilized Stern-like layer around the DNA molecule. The technique presented here is more informative and convenient for surface charge detection than the current commercial systems based on isoelectric focusing (IEF).

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