An effect of protruding ends of λ-DNA on its adsorption onto hydrophobic solid surfaces during molecular combing

We investigated an effect of difference in extremities of DNA on its adsorption onto chemically modified cover glass slips. Two kinds of DNA were used. These are lambda-DNA and lambda-DNA treated with T4 DNA polymerase, which have protruding ends and blunt ends, respectively. The glass substrate surfaces were silanized with 3-aminopropyltrimethoxysilane (APS) or octadecyltrimethoxysilane (OTS). Both DNA molecules were adsorbed on the APS-treated surface due to electrostatic interaction between the positively charged ammonium groups and the negatively charged phosphate groups along the DNA chains, while only untreated lambda-DNA was adsorbed on the OTS-treated surface. The latter result is attributable to hydrophobic interaction between the protruding ends and the OTS-treated surface.