Adhesion of DNA nanostructures and DNA origami to lithographically patterned self-assembled monolayers on Si[100

Abstract

Cationic self-assembled monolayers (SAMs) can easily be formed on silicon dioxide via siloxane chemistry, and these SAMs provide robustly attached surface charges that anchor DNA nanostructures and origami. The surface charge of the SAM can be controlled by formation of mixed monolayers of aminopropyltriethoxysilane (APTES) and trimethyl aminopropyltrimethoxysilyl chloride (TMAC). X-ray photoelectron spectra of mixed monolayers show surface charges ranging from about 1 to 3 charges per nm 2 . At high mole fractions of APTES, binding defects such as folded and rolled origami are common; at moderate mole fractions of APTES, binding metrics for DNA origami are comparable to mica, and on pure TMAC, binding is weaker than on mica. In order to locate individual DNA nanostructures at desired sites, 35-40 nm APTES dots or 125 nm APTES stripes were fabricated by a combination of EBL and molecular liftoff. Deposition of small DNA nanostructures (8 nm × 37 nm × 2 nm) or DNA origami (60 nm × 90 nm) was conducted in 0.1-1.0 micromolar solution. The binding selectivity between the anchor pads and the background silicon dioxide was at least 50:1. The DNA origami are persistently attached and can be imaged in air after rinsing the substrate in flowing water.