Direct observation of λ-DNA molecule reversal movement within microfluidic channels under electric field with single molecule imaging technique

• Published in: Chinese physics B Vol. 25; no. 7; pp. 525 - 533
• Main Author: 杨凤云 王凯歌 孙聃 赵伟 王海青 何鑫 王归仁 白晋涛
• Format: Journal Article
• Language: English
• Published: 01.07.2016
• Subjects: 分子传感器; 单个DNA分子; 单分子; 实验室芯片; 流体通道; 电场作用; 荧光成像技术; 运动方向
• ISSN: 1674-1056; 2058-3834
• DOI: 10.1088/1674-1056/25/7/078201

The electrodynamic characteristics of single DNA molecules moving within micro-/nano-fluidic channels are important in the design of biomedical chips and bimolecular sensors. In this study, the dynamic properties of λ-DNA molecules transferring along the microchannels driven by the external electrickinetic force were systemically investigated with the single molecule fluorescence imaging technique. The experimental results indicated that the velocity of DNA molecules was strictly dependent on the value of the applied electric field and the diameter of the channel. The larger the external electric field, the larger the velocity, and the more significant deformation of DNA molecules. More meaningfully, it was found that the moving directions of DNA molecules had two completely different directions：（i） along the direction of the external electric field, when the electric field intensity was smaller than a certain threshold value;（ii） opposite to the direction of the external electric field, when the electric field intensity was greater than the threshold electric field intensity.The reversal movement of DNA molecules was mainly determined by the competition between the electrophoresis force and the influence of electro-osmosis flow. These new findings will theoretically guide the practical application of fluidic channel sensors and lab-on-chips for precisely manipulating single DNA molecules.