Fluorescence observation and manipulation of individual DNA molecules in a microfluidic channel

Observation and manipulation of a single DNA molecule in real time have been applied for gene analyses and novel biochemical analyses of DNA-protein interactions. The DNA molecule in solution frequently changes its position and its shape due to Brownian motion, therefore precise handling technique is required. At the same time, miniaturized chemical reaction systems such as micro total analysis systems (μTAS) have been actively studied in recent years. Fluid control in microchannel networks is one of the most important aspects of μTAS. This fluid control technique is available for not only chemical analysis but also single-molecule DNA analysis. Here, we describe two topics concerning the single-molecule DNA manipulation. The first topic is surface treatments for anchoring individual DNA molecules in a microchannel. We focused attention on phospholipid bilayers. We have obtained clear images of the DNA molecules by using supported lipid bilayers made from amphiphilic lipids which prevent the nonspecific surface adsorption of DNA. The second topic is manipulation of individual DNA molecules by applying high voltage electric field. The electric force can be easily applied and move DNA molecules in a bulk system. We have tried to stretch DNA molecules in viscous solution by applying high voltage electric field. These manipulation techniques may contribute for accelerating novel single-molecule DNA analysis.