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Open Access Nano Express

DNA stretching on the wall surfaces in curved microchannels with different radii

Shou-Shing Hsieh*, Fong-He Wu and Ming-Ju Tsai

Author Affiliations

Department of Mechanical and Electromechanical Engineering, National Sun Yat-Sen University, 80424 Kaohsiung, Taiwan

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Nanoscale Research Letters 2014, 9:382  doi:10.1186/1556-276X-9-382

Published: 7 August 2014

Abstract

DNA molecule conformation dynamics and stretching were made on semi-circular surfaces with different radii (500 to 5,000 μm) in microchannels measuring 200 μm × 200 μm in cross section. Five different buffer solutions - 1× Tris-acetate-EDTA (TAE), 1× Tris-borate-EDTA (TBE), 1× Tris-EDTA (TE), 1× Tris-phosphate-EDTA (TPE), and 1× Tris-buffered saline (TBS) solutions - were used with a variety of viscosity such as 40, 60, and 80 cP, with resultant 10−4 ≤ Re ≤ 10−3 and the corresponding 5 ≤ Wi ≤ 12. The test fluids were seeded with JOJO-1 tracer particles for flow visualization and driven through the test channels via a piezoelectric (PZT) micropump. Micro particle image velocimetry (μPIV) measuring technique was applied for the centered-plane velocity distribution measurements. It is found that the radius effect on the stretch ratio of DNA dependence is significant. The stretch ratio becomes larger as the radius becomes small due to the larger centrifugal force. Consequently, the maximum stretch was found at the center of the channel with a radius of 500 μm.

Keywords:
DNA stretching; Microchannel; μPIV; Curve effect