DNA stretching on one-sided carbon nanotube (CNT) walls in microchannels

Completely stretched DNA molecules are becoming an important topic to advance our fundamental understanding of the physical and biological properties of DNA. In this study, λ phage DNA molecules are stretched on multi-walled carbon nanotube (MWCNT) films on the wall surfaces in a microchannel and measured through the total internal reflection fluorescence microscopy visualization/measuring technique. With DNA stretching in a definite direction, it is expected that a higher stretch ratio will be obtained. Real-time images show that the stretch ratio of the λ phage DNA molecules on the MWCNT walls reaches about 0.7 (relative to its contour length) at a low electrical field strength of 5 kV m−1, which is significantly higher than without the MWCNT-deposited film. Special attention is paid to the effect of the MWCNT film thickness, the channel size, in terms of the aspect ratio of the channel cross-section and channel length, and different electrical field strengths.