Stretching of single DNA molecules complexed with restriction endonuclease by Langmuir-Blodgett method

We have proposed a new technique for stretching single double-stranded DNA molecules on solid substrates by the Langmuir-Blodgett (LB) method. The polyion complex monolayer of a cationic amphiphile and DNA molecules formed at the air-water interface was transferred on a clean glass substrate. Vertical lifting up of the glass substrate provided the transferred monolayer consisting the stretched individual DNA molecules aligned parallel to the lifting direction on the glass. The DNA molecules complexed with the restriction endonuclease (EcoRI) were employed for stretching by using this method. Fluorescence images of the transferred monolayer showed that the EcoRI-binding DNA molecules could be stretched and immobilized on the glass substrate. A specific sequence of DNA recognized by EcoRI was detected as spatial positions of the stretched DNA molecules.