Alignment of λ-DNA on Organic Monolayer Surface Patterned by Scanning Probe Lithography

With the combination of a molecular combing technique and scanning probe lithographic patterning, λ-DNA wires were stretched and aligned to form parallel lines on a patterned organic monolayer surface. The patterned organic monolayer was composed of hydrophilic aminopropyltriethoxysilane (APS) in the middle of hydrophobic octadecyltrichlorosilane (OTS) on a silicon surface. The stretching and alignment of λ-DNA wires were induced along the lines of the APS layer which attracted λ-DNA through a coulombic interaction at an early stage of the combing. Weaker van der Waals interaction with the OTS layer induced a settlement of the wire after the sample was dried. The aligned structures were confirmed by tapping-mode atomic force microscope images, aided by positively-charged gold nanoparticles exclusively attached to the DNA backbone.